압축기의 종류는 크게 dynamic type과 positive displacement type으로 우선 나눌 수 있다. 전자는 제트엔진에 사용되는 압축기에서 보는 바와 같이 기체의 속도를 변화시켜 동압을 정압으로 바꾸어 압력을 얻는 경우이다. 후자는 기체를 둘러싼 체적을 줄여서 압력을 얻는데 가전제품에 쓰이는 냉각용 압축기의 대부분의 종류가 이에 해당된다. 압축 기체의 종류에 따라 공기 압축기, 가스 압축기, 냉각용 압축기로도 나눌 수 있겠다. 냉각용 압축기는 다시 여러 가지 방법으로 분류할 수 있겠지만, 구동 모타의 용량이나 냉각 용량에 따라, 대형, 소형으로 분류하거나, 압축기를 둘러싼 셀의 구조에 따라 밀폐형과 반 밀폐형으로 나눌 수 있다. 밀폐형은 냉매를 반 영구적으로 보충할 필요가 없도록 용접형 셀을 가진 구조로 압축기를 다시 열어서 보수할 수가 없다. 냉장고나 냉방기 같은 가전 제품에 쓰이는 압축기는 대부분 소형 밀폐형이 되겠다. 산업용의 중,대형 압축기는 보수의 목적으로, 자동차 냉방용 압축기는 동력이 엔진축에서 공급되는 구조 상의 이유로 반 밀폐형이 채택된다. 보수가 사실상 불가능한 밀폐형의 구조 상 소형 냉장용 압축기는 거의 무한 수명을 감안한 설계를 요하게 되고, 이것이 압축기의 보수적인 설계 및 개발 성향에 어느 정도 영향을 주었다고 볼 수 있다. 이런 소형 밀폐형 압축기(positive displacement, fractional horsepower, hermetic compressor)에 관한 연구의 소개가 이 글의 주 관심이 되겠다. 압력을 얻기 위해 체적을 변화시키는 mechanism도 여러 가지가 있는 바, 왕복동식 피스톤(reciprocating piston) 압축기가 가장 오랫동안 사용되어 온 구조이다. 회전식으로 압축을 얻는 방식으로는 로타리 피스톤식, 스크류식, 스크롤식 압축기가 있다. 로타리 피스톤(rotary piston)식 압축기는 약 20여년 전 부터 냉방용 압축기에서부터 널리 쓰이게 되었다. 약 10여년전부터 상용화 된 스크롤(scroll) 형 압축기도 현재 상대적으로 용량이 큰 가정용 냉방기를 중심으로 많이 쓰이고 있다. 스크류형 압축기는 보통 중대형 상업용에 주로 쓰인다.

The powertrain is a system of exciters which are connected by vibration transmitters and noise radiators. The powertrain has infinite natural frequencies. If the engine explosion, excites a certain natural frequency, then the powertrain system seriously vibrates. The torsional vibration arises from here. Torsional vibration like this can cause various noises as rattle and booming. In this study, the simulation models of multiple degrees of freedom were developed to reduce the torsional vibration of the powertrain. These models are combined mass moment of inertias with torsional springs. The free and forced vibration analyses were carried out by these models; and the validity of the simulation models were checked by the field test. The reduction effect of the torsional vibration along the driveline design factor is presented by the analytical results.

In order to compute the forces which are transmitted through rubber bushings with a commercial multibody dynamic analysis (MBDA) program, a rubber bushing model is needed. The rubber bushing model of MBDA programs such as DADS or ADAMS is the Voigt model which is simply a parallel spring-viscous damper system, meaning that the damping force of the Voigt model is proportional to the frequency. However, experiments do not necessarily support this proportionality. Alternatively, the viscoelastic characteristics of rubber bushings can be better represented by the complex stiffness. The purpose of this paper is to develop a viscoelastic rubber bushing model for the MBDA programs. Firstly, a methodology is proposed to calculate the complex stiffness of rubber bushings considering static and dynamic load conditions. Secondly, a viscoelastic rubber bushing model developed which uses standard elements provided by DADS. The proposed methods are applied to the rubber bushings of the lower control arms of a rear suspension of a 1994 Ford Taurus model. Then, the forces computed for the rubber bushing model are analyzed and compared with the Voigt model in time and frequency domains.

In this paper, a kinematic and dynamic model for an excavator is presented. A graphic user interface program for kinematic-dynamic analysis for the excavator is developed. To predict the stiffness and damping properties of the joint between the vehicle and the track, a parameter study is executed. Using the predicted joint stiffness and damping, the jerk simulation for the excavator is reproduced. Simulation results are compared with the test results to confirm the validity of the simulation model.

The coupled vibration occurs between traveling vehicle and bridge, when vehicle runs on it. The natural frequency of this coupled system is dependent on the contact position of vehicle and bridge, that is, time-varying system. The calculations of these natural frequencies are very complicated, and often carried out by using Green function theory, series. But, these methods have any limitations, such as, supporting condition, boundary condition. In this paper, on the coupled system constructed by the concentrated mass and elastically supported beam, an analytical method of natural frequency is proposed by using Fourier sine transformation. The results are compared and discussed with numerically calculated ones.

This paper presents modal contribution method to reduce vehicle vibration. Normal mode analysis is performed to obtain modal vector matrix. The proposed method uses this modal vector matrix to evaluate forced response of an active mode to the applied engine forces and the rotating force due to wheel unbalance mass. Comparing the responses, of the specific active mode with one another, it can be easily done to determine most contributed mode in the interesting frequency band. Then we can find dominant bushes by the strain energy distribution of the mode. Vibration response is decrease with modification of those bushes.

In this paper, a design tool using continuum design sensitivity analysis (DSA) method has been developed for noise, vibration, and harshness (NVH). Design sensitivity is formulated, implemented numerically, and named SENS1. SENS1 can compute the design sensitivity using model and response files of MSC/NASTRAN of vehicle. A of real vehicle model is considered to validate SENS1. Numerical study shows SENS1 is a useful tool to improve NVH performances of vehicle body.

본 연구의 목적은 수도권 지하철차량의 소음과 진동에 방음차륜(또는 탄성차륜)이 어느 정도의 효과를 가져오는가를 평가하기 위한 것이다. 실차시험을 통하여 일체차륜이 장착된 차량과 방음차륜이 장착된 차량의 차내소음 및 차체진동을 비교하여 보았다. 그 결과 방음차륜은 지하철차량의 소음과 진동에 효과가 있음을 알 수 있었다. 그러나 실제 적용은 소음과 진동 이외에도 여러 가지 측면에서의 검토가 이루어져야만 가능할 것이다.

차량에서 인체가 노출되는 진동환경으로서 좌석과 바닥에서의 진동사이에 위상차가 존재하는 경우에 대한 인체의 반응을 주관평가 실험을 통해 분석하였다. 인체가 진동에 민감하게 반응할 뿐만 아니라 인체와 좌석으로 구성되는 진동시스템의 공진주파수와 관련된 2.5, 3.15, 4, 5, 6.3 Hz의 주파수에서, 진동의 크기를 각각 0.25, 0.4, 0.63, 1.0, 1.6m/s$^{2}$로 변화시켜 가며 위상차가 인체의 안락성에 어떻게 영향을 미치는 지를 분석하였다. 두 진동간의 위상차는 진동량이 적을수록, 또 주파수가 낮을수록 인체의 안락성에 악영향을 미쳤다. 진동의 진폭이 0.25m/s$^{2}$ 일 때 위상차가 180.deg.인 경우의 불편함은 0.deg.인 경우보다 2.5배 정도 큰 것으로 나타났다. 특히 현가장치가 장착된 의자의 경우에는 좌석과 바닥진동의 위상차이가 안락성에 미치는 영향을 정량적으로 파악하여 인체-좌석 시스템의 공진주파수를 선정해야 함을 알 수 있다.

Statistical Energy Analysis(SEA) has been considered as a possible method for predicting responses of complex structures, especially at higher frequencies. In this paper, an SEA model of vehicle was built using 138 energy storing subsystems connected together using 1019 junctions. SEAM software program was used to build and calculate the model. To demonstrate the accuracy of the SEA model, predicted response levels were compared with measured levels. The source input levels were measured at the engine mounting parts. For the vibration levels, the agreement between the calculation results and the experimental ones was found to be good. The energy flow between connected subsystems can be presented, because the analysis method is based on the estimation of the power flow between subsystems. This paper also identifies some dominant energy flow paths from sources. It is finally presented that the SEA model can optimize the design parameters of vehicles using model parameters and energy flow paths.

In this paper, a global acoustic design sensitivity analysis (DSA) of field point pressure with respect to structural sizing design variables is developed. Firstly acoustic sensitivity is formulated and implemented numerically. And it is combined with continuum structural sensitivity to obtain the global acoustic, design sensitivity. For this procedure, GASA (global acoustic design sensitivity analyzer) has been developed. A half scale of automobile cavity model is considered in this paper. In order to confirm accuracy of the results of global acoustic DSA obtained by GASA, it is compared with the result of central finite difference method. In order to reduce computation time, Rayleigh approximated solution is evaluated and compared with the solution which used every nodal velocities. Also the acoustic optimization procedure is performed using design sensitivities. From these numerical studies, it can be shown that global acoustic DSA is a useful tool to improve acoustic problems.

Since rattling noise, which occur in mechanical linkage with free play or glove boxes in passenger cars, play an important role in the generation of industrial noise and vibration, it is interest to study these dynamics. A difference equations are derived which described the motions of a mass constrained by pre-compressed spring and forced by a high frequency base excitation. Two types of saddle are founded from these difference equations and the stable and unstable manifolds are constructed in these saddle point. For a certain region in a parameter space of exciting displacement and coefficient of restitution, transversal intersections of stable and unstable manifolds exist. Therefore it is founded that there are large families of periodic and irregular non-periodic motions in rattling system i.e. chaos motion is observed.

This paper presents the psychoacoustic analyses on the vehicle interior, noise generated when accelerating. Following the objective quantification for vehicle noises of different classes, the subjective decision process by the jury test is adopted to interrelate these results based on two different approaches. In particular, the paired comparison method is employed in assessing the sound quality in terms of the quietness, the powerfulness, and the pleasantness of the human auditory sensation. Special attention is paid to the physical interpretation of psychoacoutic parameters and their interrelation to the subjective assessment scores. In order to ensure the integrity of statistics of the survey, various tests are performed. The results show that the consistency of the "quiet" sensation is far higher than that of the "powerful" and the "pleasant" sensations. Also, it is found that the most significant parameter determining these feelings turns out to be the inherent loudness of the noise instead of the conventional indicators such as the weighted sound pressure level. It may be concluded that the psychoacoustic analysis offers more realistic evaluation for vehicle noise and assists the improvement of NVH more efficiently.ement of NVH more efficiently.

UTM-01 is the first fall sized maglev test vehicle which is being developed by KIMM and Hyundai Precision and Industrial Co., since 1995. The vehicle employs normal conducting magnets for levitation and single sided linear induction motor for propulsion. The test vehicle has been under tests to assure its required performance since last May 1997. This paper reports various system level test results compared with simple 2 degree of freedom dynamic calculations. Test results include performance of the levitation and guidance system, propulsions system, and the dynamic behavior of the elevated guideway under the passage of the maglev vehicle.

Nonclassically damping comes from drastic variations of energy absorption rates of the materials in different parts of structures, or from the external damping sources inserted into the structures. In this study, an approximate method based on the real valued normal modes to analyze the responses of a nonclassically damped system under stationary random excitations has been suggested. The dynamic responses of an aircraft landing gear under stationary random excitations has been analyzed using the proposed method. It has been found by a series of simulation that this method is superior to other approaches in respect of computational effort and accuracy.

This paper presents the model updating of an equipment panel by using modal test and sensitivity analysis. The equipment panel is one of the major structures of communication satellite, on which broadcasting and communication equipments are mounted. For high rigidity and light weight, the panel was designed as an aluminum honeycomb sandwich panel. In addition, heat pipes were embedded in the panel for thermal control. It is essential to improve the finite element model of a satellite by using modal test in order to verify the satellite is designed with adequate margin under launch environment. In this paper, Young's modulus of aluminum facesheet was selected as a modified parameter by sensitivity analysis. The effect of rotational springs of boundary points was also considered.

본 논문에서는 실용급 위성으로는 국내에서 처음 개발되는 다목적 실용위성의 개발과정 중 준비행모델에 대한 발사환경 시험에 관련된 내용의 일부를 관련분야의 전문가들에게 소개하는데 중점을 두었다. 장시간의 개발기간과 고비용이 소요되는 위성체를 성공적으로 설정궤도에 발사하기 위해서는 소음 및 진동에 관련된 심도있는 연구가 필수적이며, 향후 우주 분야의 독자적인 기술 개발시 국내 관련분야 전문가들의 노력이 절대적으로 필요하다.

The Reciprocating compressor are widely used in the refrigeration field for its simplicity in principle and high efficiency. In this work, we developed a mathematical model of a reciprocating compressor. The suction and discharge valves are modeled by the spring-mass-damper systems. The working fluid flow is derived from unsteady Bernoulli's equation. With the design parameters, the valve motions and pressure fluctuations are studied numerically and experimentally.

Despite the fact that vibration and noise of suction and discharge valves are important factors to be considered in reciprocating compressor designs, such are still have many problems to be developed. Subsequently, this paper addresses a thorough investigation to retrieve basic data for designing suction and discharge valve. In achieving this goal, the natural frequencies in suction and discharge valve were calculated using finite elements method and compared with the results of experimental method which is driven by the speaker and detected by the Laser Velocity Transducer. Also, it was found that natural frequencies are much affected by the Young's Modulus at the clamp. Therefore, improved experimental setup is suggested to consider the effect of clamping conditions. Consequently improved experimental data have good agreements with the FEM data.

In this study, nonlinear stiffness characteristics of a discharge valve in a small hermetic compressor was considered. It was approximated, with piecewise-linearity, and cubic or quintic nonlinearity by the static load-displacement experimental results. Based on the fluid-structure interaction effects and mass flow rate, the derived 1-DOF equation of motion for the valve model was analyzed. Finally, the dynamic response of the discharge valve was studied with parameters such as the ratio of the running frequency of the compressor to the linear natural frequency of the valve.

A resonance is the one of major reasons of vibration problems occurred in industrial fields. To reduce vibration level due to resonance, structure reinforcements or change of the dynamic characteristics is generally applied. In this paper, the troublesome vibration levels of the motor shaft and auxiliary condensate pump are reduced by avoiding resonance.

In this paper, BLDC spindle motor is designed using CAE/CAT to reduce structural vibration. Motor is modeled and analyzed using a finite element analysis (FEA) program and correlated to the results of modal test. Design sensitivity analysis (DSA) of frequency is carried out and validated by the modal test of modified motor manufactured. This study shows that simulation-based design can improve quality with reduced development time.

The sub-resonance modes can be easily excited by the assembling tolerance in the asymmetric type optical pick-up actuators, compared with the symmetric type. In this paper, we propose the novel method for reducing the vibration due to the sub-resonance modes where undesirable modes can be decreased by adding the damping, which can be achieved by increasing the flexibility of holder PCB, against to the sub-resonance modes. Using the finite element method, the change of mode shapes is investigated as the shape of holder PCB is modified. Experimental results support that the proposed method reduces remarkably the vibration of sub-resonance modes of the optical pick-up actuator.

In contrast to the conventional intake manifold of steel or aluminum material, the lst natural frequency range of plastic intake manifold becomes very lower to ca. 40Hz. That causes negative effects on the engine control unit installed inside the throttle body. In this paper, support design concepts to increase the natural frequency range larger than max. 200Hz are suggested based on the vibration analysis results using finite-element method. In conclusion, it is shown that the vibration level can be reduced most effectively by the installation of the neck support bracket between the throttle body and the plenum chamber.

An automatic Q. C. tester for a production line of electric grinder is developed using vibration signals. The methods of measuring and analyzing the vibration signals are found through several experiments at laboratory and production line. The experiments show that checking a vibration signal at running condition only, without any sound signal, is enough to judge whether the product is good or not. The Q. C. tester is made of accelerometer and PC. Measured vibration signal using accelerometer is transmitted to PC through A/D board. Vibration level are calculated using FFT algorithm in PC for already selected five frequency bands, which can specify the cause of fault. The Judging criteria of vibration levels of each bands are decided through a lot of experiment with the comparison of manual judgement.

A modelling method for the vibration analysis of rotating cantilever plates with a concentrated mass is presented. The equations of motion for the rotating plates with a concentrated mass located in an arbitrary position are derived. For the modelling of the concentrated mass, a mass density Dirac delta function is used. The effects of concentrated mass and its location, angular speed, and hub radius of the rotating plate on the natural frequencies are studied. Particularly, mode shape variations due to some parameter variations are investigated.

In the tandom pencil slat saw lines, feeding of cedar blocks is often stopped because excessive motor current is required in a saw machine. These events are called "kickoffs' in factory lines. Kickoffs decrease productivity due to machine down-time and damage to saw blades often accompanies them. Researches on saw behavior at kickoff are required to understand and reduce the frequency and severity of kickoff events. This research aims at understanding the fundamental mechanisms of kickoffs during cutting, predicting the impending kickoff and evolving design improvements for high cutting performance with fewer and less severe kickoffs.offs.

축어긋남이 있는 회전체-볼베어링계에 대한 동적모델을 이용하여, 각축어긋남에 의한 2x 축진동현상을 조사하였다. 이때 유효베어링강성계수를 정의하여 축어긋남과 불균형량에 의해 발생되는 강성계수의 평균과 동기 변화성분을 운동방정식에 도입하였다. 수치해석과 실험결과는 각축어긋남에 의한 바나나 형태의 선회궤적이 회전체계 임계속도의 1/2이 도는 속도영역에서 뚜렷이 나타나는 것을 보여주었다.

Although discretization methods such as the transfer matrix method (TMM) and the finite element method (FEM) have played an important role in the design or analysis of rotor-bearing systems, continuous system modeling and analysis are often desirable especially for sensitivity analysis or design. The present paper proposes a comprehensive modeling procedure to obtain exact solution of general rotor-bearing systems. The proposed method considers a Timoshenko beam model and makes use of complex coordinate in the formulation. The proposed method provides exact eigensolutions and frequency response functions (FRFS) of general multi-stepped rotor-bearing systems. The first numerical example compares the proposed method with FEM. The numerical study proves that the proposed method is very efficient and useful for the analysis of rotor-bearing systems.

A study on dynamic characteristics of rotating disks in magneto optical disk drives is presented. Natural frequencies of rotating disks are investigated experimentally and numerically. The frequency response and critical speeds of the ASMO disk are discussed. The characteristics of airflow around the disk and their effects on disk vibrations are also investigated. It is found that the numerical calculation of the natural frequencies of rotating disks agrees well with the experimental results. The airflow around the disk in the cartridge affects the characteristics of the disk vibrations to reduce the modal frequencies of the disk. The experiment shows that negative vertical offsets of the disk in the cartridge possibly increase the vibration amplitudes. As being influenced by the geometry of the cartridge, the rotation of the disk causes an asymmetric airflow in the presence of window.

A disk rotor dynamic analysis program called by DR. DAP is developed for disk drive spindle systems to analyze dynamic characteristics in operation and to estimate the effects of excitation sources. It is applicable to design for stabilization and to select parts of disk drive spindle systems. The disk drive spindle system in this program is modeled as a flexible shaft with multiple flexible disks, which is supported by bearings and driven by electric motor, and its complicated coupled vibration characteristics are analyzed by using a substructure synthesis technique with the assumed-modes method. All the coupled modes of interest can be well predicted by the example of a three disk hard disk drive with the three tuning parameters. It is also shown that, with the introduction of the excitation sources associated with the defects of ball bearing systems, the magnetic unbalance of spindle motor, the program can well predict the stability of the system, i.e., the possibility of resonance.

Recent trends and the effect of mechanical vibrations in optical disk drives are reviewed in this paper. The Nation from CD drives to high density DVD drives and the development of writable optical disk drives require tighter mechanical tolerance. The demand for faster access time and higher data transfer rate also leads to critical mechanical problems to limit the tracking and focusing servo performance. The current mechanical issues to limit the performance of the drives and various technologies to overcome the mechanical problems are introduced. Vibrations of disk-spindle system, actuator and suspension designs of the optical pick-up, and general mechanical designs for the fast and stable access mechanism are considered.

This work focuses on the analysis of dynamic characteristics of an optical disk drive, Dynamic performance of the drive plays an important role in the design of a mechanism where the quality of servo mainly affected by the quality of controlling focus error and tracking error, A finite element model of the optical disk drive is presented to demonstrate its dynamic behaviors. Experimental results for the drive are presented and compared to predictions from the finite element model for verification. Using the finite element model, dynamic responses are predicted under internal and external excitations. Some design parameters of the vibration isolators are presented, satisfying the requirements of DVD drive system.

In this work, to identify the dynamic characteristics of disk-spindle system in hard disk drive, experimental modal analysis was performed. And an experimental analysis system including testing apparatus, precision sensors, and analysis software was established in order to perform the testing effectively. From the experimental results, coupled and uncoupled modal characteristics of 3-disk spindle system are clearly identified.

Measurement technique using only one sensor for complex modal testing of the asymmetric rotor is proposed. The reverse directional frequency response function of asymmetric rotor, which is known to be indicative of the degree of asymmetry in a symmetric rotor, is also shown to be identified with simplest technique requiring only one sensor and one excitor. It lessens the testing efforts and its practicality is verified by numerical simulation. The measurement and excitation techniques for complex modal testing are also summarized so that the efficient complex modal testing can be possible according to the kind of rotor system.

The present paper improves the direct identification scheme based upon the equation error formulation with incomplete modal data. First, an indirect estimation technique is considered for estimating unmeasured elements of latent vectors by the combined use of a model and measured incomplete eigen vectors. It is used for estimating the other elements of eigen vectors, which are essential for identification but not available. Next an index is introduced here to indicate the quality of estimation with respect to the mode and the measured positions. A sensitivity formula for eigenvalues with respect to the unknown joint coefficient is also derived to select the modes appropriate for identification. An identification strategy is suggested to meet with practical problems with the help of the index and sensitivity formula. The index and the sensitivity are proved to be useful for selecting measurement positions and modes appropriate for identification A comprehensive simulation study is performed to test the proposed method.

Pump-storage power plants, which pumps water from the lower reservoir to the upper reservoir using the extra electronic power at night and generates the electronic power in the daytime, are more increasing. Currently it has a tendency to be high-head large-capacity machines. So in the processing of design, we need to know the vibration characteristics of pump-turbine shaft system sufficiently. In this paper, we developed the computer programs for analyzing pump-turbine shaft system considering magnetic force of generator, hydraulic force at runner, dynamic characteristics of guide bearings and the effect of add mass of water. And the superiority of this program was verified by applying it to the real model and calculating high quality critical speed, natural mode and unbalance response.

A detailed rotordynamic design analysis is performed with a turbo-chiller compressor rotor-bearing system. A pinion is machined into a compressor shaft and the pinion is driven by a bull gear to a rated speed of 14,600 rpm. Utilizing a finite element method each bearing loads are calculated considering various gear loadings as well as the rotor weight itself. A Partial bearing and a 3-Lobe bearing are designed as the compressor impeller out-board bearing and in-board bearing, respectively. Finally a complex rotordynamic analysis of the compressor rotor-bearing system is carried out to evaluate the system whirl natural frequencies, stabilities, and unbalance responses.

In this study, the in-situ parameter identification method for active magnetic bearing (AMB) actuator based on an open-loop balancing scheme is proposed. The scheme utilizes the relation between the compensating voltage and the known unbalance force. Main advantage of this method is that it is easy to use, yet it gives the actuator dynamics on the actual operating condition of an AMB system. The experimental results show that the proposed scheme compensates the known unbalance accurately and consequently identifies the actuator dynamics effectively.

A new signal processing technique, the directional harmonic wavelet map(dHWM), is presented to characterize the instantaneous planar motion of a measurement point in a structure from its transient complex-valued vibration signal. It is proven that the auto-dHWM essentially tracks the shape and directivity of the instantaneous planar motion, whereas the phase of the cross-dHWM indicates its inclination angle. Finally, the technique is successfully applied to an automobile engine for characterization of its transient motion during crank-on/idline/engine-off.

An immune system has powerful abilities such as memory, recognition and learning to respond to invading antigens, and is applied to many engineering algorithm recently. In this paper, the combined optimization algorithm is proposed for multi-optimization problem by introducing the capability of the immune system that controls the proliferation of clones to the genetic algorithm. The optimizing ability of the proposed optimization algorithm is identified by using two multi-peak functions which have many local optimums and optimization of the unbalance response function for rotor model.

이 글의 구성은 다음과 같다. 1. 소개 2. 한국의 활동 3. ISO 규격 제정단계 4. TC 108 22차 총회 내용 5. TC 108/SC 5 4차 분과위원회 내용

ISO/FDIS 11342: 1998(E)에서, "회전체 밸런싱의 목표는, 기계 설치후 만족스런 운전(satisfactor running)을 이루는 것이다. '만족스러운 운전'이란, 회전체에 잔류하는 불평형 질량에 기인한 진동이 진동허용치(acceptable magnitude of vibration)를 넘지 않는 것을 의미한다"고 밸런싱을 설명한다. ISO/TC108(Mechanical vibration and Shock)의 Subcommittees 중 SC1은 'balancing, including balancing machines'라는 소그룹명을 갖고 있다. 이 SC에서는 회전체 밸런싱에 관련한 ISO의 제정과 개정의 일을 한다. 1998년 현재 위 위원회를 통하여 새롭게 개정된 ISO/FDIS 11342:1998(E)과 현재 개정 마무리 단계에 있는 ISO/DIS 2953을 간략히 소개한다.

ISO TC108/SC2에서 취급하는 기계, 차량 및 구조물에 발생되는 기계진동과 충격의 측정 및 평가 기준에 대하여 살펴보았다. SC2내에는 현재 7개의 Working Group(WG)이 23개 기준에 대하여 보완 및 개정작업을 지속하고 있다. 이들 기준의 적용대상은 회전기계, 선박, 철도차량, 자동차 및 건물로서 본문에서는 기준 내용을 요약하고 개정과정도 일부 소개한다.

In this experiments of design, vibration evaluation, and test of vehicles, aircraft, and other mechanisms the development of vibration simulator that serves environment similar to real fields takes lots of advantages. Especially, in the real field test of vehicles it possesses the advantages of showing the dynamic characteristics of the vehicle. In this study, to investigate the validity and fitness of proposed 6DOF parallel link mechanism we simulated that mechanism.

In the production of semiconductor wafer, optical and electron microscopes, ion-beam, laser device must maintain their alignments within a sub-micrometer. This equipment requires a vibration free environment to provide its proper function. Especially, lithography and inspection devices, which have sub-nanometer class high accuracy and resolution, have come to necessity for producing more improved giga and tera class semiconductor wafers. This high technology equipments require very strict environmental vibration standard, vibration criteria, in proportion to the accuracy of the manufacturing, inspecting devices. The vibration criteria of high sensitive equipment should be represented in the form of exactness and accuracy, because this is used as basic data for the design of building structure and structural dynamics of equipment. The study on the evaluation of the factors affecting the permissible vibration criteria is required to design the efficient isolation system of the semiconductor manufacturing of equipment. This paper deals with the properties of the effected factor for vibration criteria of high sensitive equipment.

In this paper, the power flow analysis(PFA) method is applied to the prediction of the vibrational energy density and intensity of coupled co-planar plates. To cover the energy transmission and reflection at the joint of the plates, the wave transmission approach is introduced with the assumption that all the incident waves are normal to the joint. By changing the frequency ranges and internal loss factors, we have obtained the PFA results, and compared them with the analytical exact solutions.

Structural intensity of plates experiencing bending vibration is analytically evaluated using the modal analysis based on the assumed mode method. In the analysis, material internal loss and localized damping are considered. The power obtained by structural intensity integration over the circle containing the excitation source is compared with the power injected into plates to verify the accuracy of the presented method and; to evaluate the convergence of mode superposition. The intensity integration is carried out varying the circle radius and the integral step to investigate their effects in case of the power estimation using structural intensities. In addition, the dominant component among internal forces in the energy transfer by the bending vibration of a stiffened plate is investigated.

A method for analysis of the free vibrations of the composite cylindrical shell with a longitudinal, interior rectangular plate is developed by using the receptance method. This method is based on the ratio of a deflection(or slope) response to a harmonic force(or moment) at an joint point. The natural frequencies of the combined shells calculated numerically. The results are compared with the experiment and a finite, element analysis results in order to validate the formulation. The effects of the location and thickness of the plate on the frequencies are also investigated.

The free vibration analysis of the simply supported steel and composite cylindrical shells are investigated. The natural frequencies and mode shapes of the shell are experimentally obtained by impact testing using an impact hammer and an accelerometer. The effects of the material and geometry on the vibrational characteristics of the shell are examined. The experimental results are compared with the analytical and a finite element results. They showed good agreement with each other.

In order to improve the prediction of dynamic behavior in structures, several lower vibration modes from FFT analysis through experiments are used to update the mechanical properties followed by the updated frequencies from numerical analysis. Performance index consists of the sum of error norms between the chosen frequencies and corresponding frequencies from numerical analysis. As an updating process of the natural frequencies, the optimization algorithm based on conjugate gradient method is adopted. The gradient of performance index is calculated using the sensitivity of selected eigenvalues with respect to each design parameter. The mechanical properties of lamina, E$\_$l/, E$\_$2/, .nu.$\_$12/ and G$\_$12/, are design parameters for the updating process. The proposed method is applied to predict the dynamic behavior of composite laminated plates of [0]$\_$8T/ and [.+-.45]$\_$2S/ separately or interchangeably. Also, the mixed case for [0]$\_$8T/ and [.+-.45]$\_$2S/ is exarm'ned to check the possibility for the improved prediction generally. The good agreement is obtained between the measured frequencies and the numerical ones. Based on the results for all the cases studied, the proposed approach has a clear potential in characterizing the mechanical properties of composite lamina.

An analytical method for evaluating the free vibration of two circular plates coupled with water was developed by assuming the clamped boundary condition of the plates and an ideal fluid. The method was applied to analyze the transverse vibration modes, in-phase and out-of-phase, and the results were compared to those obtained by the finite element method (FEM) using a commercial ANSYS 5.2 software. It was found that the theoretical results can predict well the coupled natural frequencies for all in-phase modes with good accuracy. However, the analytical method shows some discrepancies compared with FEM analysis in predicting the coupled natural frequency of the out-of-phase modes, except when m = 0, the zero nodal circle. The analytical method also applied to evaluate the characteristics of the natural frequency with respect to the major parametric variation in mode numbers and distance between the circular plates.

In general, we have used the finite element method(FEM) to find natural frequencies of plates. In this method, however, it is necessary to use a large amount of computer memory and computation time because the FEM requires many degrees of freedom for finding natural frequencies of plates correctly. Therefore it was very difficult to analyze the free vibration of plates correctly on personal computer. For overcoming this disadvantage of the FEM, the authors have developed the finite element-transfer stiffness coefficient method(FE-TSCM) which is based on the concept of modeling techniques in the FEM and the transfer of the stiffness coefficient in the transfer stiffness coefficient method. In this paper, we formulate free vibration analysis algorithm of rectangular plates using the FE-TSCM. Some numerical examples of rectangular plates are proposed, and their results and computation times obtained by the FE-TSCM are compared with those by the FEM and the finite element-transfer matrix method in order to demonstrate the accuracy and efficiency of the FE-TSCM.

The effects of boundary conditions on natural frequencies for the ring stiffened composite cylindrical shells are investigated by theoretical method. The Love's thin shell theory and the discrete stiffener theory with beam functions in the Ritz procedure are used to derive the frequency equation. Five different boundary conditions such as clamped-clamped, simply supported-simply supported, free-free, clamped-free, clamped-simply supported are considered in this study. Also, the experimental investigation is presented to validate the theoretical results.

In this study, the method of analysis which is developed for calculating dynamic train loads and ground vibration by Shin-Chu Yang is verified comparing measurements of real structure. The results of analysis are agreed well with measurements of ground and structural vibration induced by passing train. The vibration level of analyzed results which is more than that of measured gives conservative result. To analyze frequency characteristics, the analyzed results are applied to the ISO environmental vibration regulation and reveal the possibility of application in analysis of frequency characteristics.

As the requirement of high-rise buildings in big cities increases, steel structural system becomes more popular in spite of the relatively higher material cost compared to that of the concrete structural system. Most of the steel structure adopts metal deck floor system because of the easiness in construction. However, the metal deck floor system has a weakness on vibration which became very important factor in office buildings, hotels and residential buildings as the more sensitive machines being used. Therefore, most, of the building codes in many countries restrict the natural frequency of the each floor should be higher than or equal to 15 Hz. Floor vibration of the KEM deck composite floor system which has been , developed recently from the engineers and scientists in Korea was measured. Also, the simplified analytical derivation of natural frequency for each floor was studied according to the measured natural frequency for each different boundary condition of the floor. As the length of the slab gets bigger, the natural frequency of the slab becomes lower even though the structural designer still considers it as a one-way slab.

Basting vibration and air blast were measured by particle velocity and overpressure as well as environmental unit, dB(V) and dB(A). Variables for vibration and noise show good relationship and proportional equations are suggested. But there are some variations, and it means that predictions by design variables are not valid for human damage estimation or limit application of regulations.

Vibration-resistant rubbers, whose elastic and shear behaviors are similar to viscoelastic materials, are used to make brace-typed dampers to reduce the building vibration. Experimental study is carried out to find the vibration characteristics of the dampers installed in the building model. The natural frequencies and modal damping ratios are obtained from the free vibration test and Fourier analysis. Analytical model of the modal strain energy method are used to find the viscoelastic characteristics of the brace-typed dampers from the experimental results. Finally shaking table test is performed to find the response behavior of the building model under earthquake loading. The present experimental study shows that the brace-typed dampers have the behavior of viscoelastic dampers, which increase the modal damping ratios and viscoelastic characteristics.

The effect of the changes in parameter angles(precone, droop, sweep) on the lead-lag damping was focused on. Experiment was made with hingeless 4-blade rotors and NACA 0012 airfoil. For the measurement of the rotating natural frequencies and lead-lag damping, non-rotating swash plate was oscillated at the regressing lag mode frequency and the data were acquired after the excitation was cut off. Analysis was made using a finite element formulation based on Hamilton's principle. The main blade is assumed as elastic beams. Quasi-steady strip theory is used to obtain aerodynamic forces, and non-circulatory forces are also included.

In order to check the validity of nonlinear normal modes of continuous, systems by means of the energy-based formulation, we consider a beam with a nonlinear boundary condition. The initial and boundary e c6nsl of a linear partial differential equation and a nonlinear boundary condition is reduced to a linear boundary value problem consisting of an 8th order ordinary differential equations and linear boundary conditions. After obtaining the asymptotic solution corresponding to each normal mode, we compare this with numerical results by the finite element method.

An investigation into the stochastic bifurcation and response statistits of an autoparameteric system under broad-band random excitation is made. The specific system examined is a spring-pendulum system with internal resonance, which is known to be a good model for a variety of engineering systems, including ship motions with nonlinear coupling between pitching and rolling motions. The Fokker-Planck equations is used to generate a general first-order differential equation in the dynamic moment of response coordinates. By means of the Gaussian and non-Gaussian closure methods the dynamic moment equations for the random responses of the system are reduced to a system of autonomous ordinary differential equations. In view of equilibrium solutions of this system and their stability we examine the stochastic bifurcation and response statistics. The analytical results are compared with results obtained by Monte Carlo simulation.

In this work, a new time integration method is proposed using the generalized derivative concept to simulate the dynamic phenomena having sudden constraint occurring in dynamic contact/impact problems. By the adoption of the generalized derivative concept and jump assumption, discontinuity can be incorporated in time integration and as a result, the algorithm does not need any other special consideration of jumps in dynamic field variables due to sudden constraint like dynamic contact-release conditions. To observe the characteristics of the proposed time integration method, the stability and convergence analyses are carried out. In numerical tests, several dynamic contact/impact problems are analyzed by straightforward application of the proposed time integration method with the exterior penalty method.

In this paper, a dynamic modeling approach is introduced to identify the dynamic characteristics of the structural/mechanical joints within an one-dimensional structure. A structural joint is represented by the four-pole parameters and the four-pole parameters are determined from the measured frequency response functions by using the spectral element method. As the illustrative examples, a cantilevered beam and a clamped-clamped beam, each consists of two beams connected by a bolted joint, are investigated to evaluate the present modeling approach. It is found that the dynamic responses predicted by using the identified four-pole parameters for the bolted joint are well agreed with the dynamic responses measured up to high frequency.

This paper presents a method of enhancing the accuracy of hybrid modelling that predicts dynamic characteristics of the coupled structure by synthesizing after FE analysis and vibration experimental analysis of the relevant individual substructure. Since most FE models in engineering problems are very large, dynamic analysis with the full FE model is costly. Frequency response function(FRF) synthesis after reducing the FE model can reduce this computational cost but introduce mode truncation error similarly in the case of considering only low-frequency mode after eigensolutions of the complete structure. This paper introduces a FRF of FE model for hybrid FRF synthesis, which is reduced by using IIRS methods and compensated through eigensolutions of the reduced model, and shows the effectiveness of the presented method.

This, paper describes formulation for time historical response analysis of vibration for tree structure. This method is derived from a combination of the transfer stiffness coefficient method and the Newmark-.betha. method. And This present method improves the computational accuracy of the transient vibration response analysis remarkably owing to several advantages of the transfer stiffness coefficient method. We regarded the structure as a lumped mass system here. The analysis algorithm for the time historical response was formulated for the tree structure. The validity of the present method compared with the transfer matrix method and the FEM(Finite Element Method) for transient vibration analysis is demonstrated through the numerical computations.

This paper presents modal characteristics of bowl parts feeder featuring piezoelectric actuators. As wellknown, the piezoelectric materials develop an electric charge proportional to a mechanical stress and vice versa. This generic phenomenon allows us to use the piezoelectric materials as sensors and actuators. Using the actuating property, we can device effective bowl parts feeder. The parts feeder activated by the piezoceramic actuators provides a large degree of freedom of controlling excitation magnitude and frequency, and thus accurate and fast feeding of various parts. As a first phase to demonstrate these advantages, a finite clement model of the bowl parts feeder is constructed and analyzed using commercial software packages. In addition, the simulated modal characteristics are compared with the measured ones to validate the proposed model.

In this paper, the axial-bending coupled equations of motion for an elastic layered beam are derived. From this equation of motion, the spectral element is formulated for the vibration analysis by use of the spectral element method (SEM). The modal analysis methodology for the present coupled field equations of motion is then developed. As an illustrative example, a cantilevered beam is considered. The correctness of the equations of motion developed herein is verified by gradually reducing the thickness of upper elastic layer to converge to the single layered elastic beam solutions. Also, the accuracy of spectral element is confirmed by comparing its results with the result by modal analysis.

A modal transducer in two-dimensional structure can be implemented by varying the distributed transducer's gain spatially. In this paper, a method based on finite element method is developed for optimizing spatial gain distribution of PVDF transducer to create the modal transducer for specific modes. Using this concept, one can design the modal transducer in two-dimensional structure having arbitrary geometry and boundary conditions. As a practical means for implementing this continuous gain distribution without repoling die PVDF film, the gain distribution is approximated by optimizing gain-weights of interface circuit. The whole spatial area of the PVDF film is divided into several electrode segments and the signals from each segment are properly weighted and summed by interface circuit. This corresponds to the approximation of a continuous function using discrete values. The electrode partition is optimized using the genetic algorithm. Gain-weights are optimized using the simplex search method. A modal sensor for first to fourth modes of aluminum plate is designed using PVDF film with gain-weighted interface circuit. Various lamination angles of PVDF film are taken into consideration to utilize the anisotropy of the PVDF film. Performance of the optimized' PVDF sensor is demonstrated by numerical simulations..

Investigation is performed on the characteristics and new control technique for general form of dynamic system under the randomly disturbance. Also, a controller design method in stochastic domain in studied, which is preliminary result in the course of research on the control of stochastic system. The governing equation is derived via F-P-K approach in stochastic sense. A controller is designed in term of auto power density and cross power density.

The vibration behavior of fuel rods has been analyzed by FEM in consideration of axial force and support spring constants. The axial compression force on the fuel rod in reactor decreases with the fuel rod burnup, and its decrease makes the natural frequencies of fuel rod considerably increase. The change of support spring constant can contribute to the remarkable change of the mode shapes, but not greatly to the natural frequencies. The reaction forces of support springs are obtained from normalizing the lst mode with the max. 0.2 mm displacement. The calculated reaction forces are larger than the previous results obtained by disregarding the deflections of the support springs.

A cross-flow fan often generates discrete noise call blade passing frequency tones. Several methods have been investigated to reduce this BPF noise, where the random distribution of blades is the most promising one. A simple and effective algorithm to determine a random distribution of blades is proposed which considers fan. performance as well as noise characteristics. The proposed method is verified by a simple numerical model and is applied in manufacturing cross-flow fan samples. Also some experiments are carried out and the experimental results are analyzed.

A constant flow-rate control valve provides effective distributions and controls of running water in a pipe system. The noise characteristics were measured to reveal the noise sources depending on pressure differences across a valve. Valve noise is mostly dominated by bubble dynamics under cavitating conditions. In this study, the sound powers from a flow control valve of constant flow rates are effectively normalized. Flow-excited dynamic systems for which there is no strong coupling between the flow and the system response can be described using a linear source-filter model. On this assumption, the normalized sound powers can be decomposed of noise source function and a response function. The source spectra in, terms of cavitation frequency show cavitation events occurring at narrow banded frequencies greater than 10 kHz. There also possibly exist two kinds of cavitating modes based on our experimental data.

The interior of open cavities exposed to a grazing flow is known to experience, strong periodic pressure, oscillations sustained for a wide range of flow velocities. In this study, an original approach was followed to develop a describing function model for the flow-excitation mechanism, governed by the shedding of discrete vortices within the shear layer over the orifice. A feedback loop analysis was performed to predict the frequency and the amplitude of the interior pressure fluctuations. Furthermore, a limit cycle stability analysis based on the extended Nyquist Stability criterion allowed the predictions of the onset and termination velocities for various modes. The analytical model was verified experimentally.

본 연구에서는 충돌면의 형상에 따른 고속 원형 충돌제트의 불안정 모드를 밝히기 위하여 우선 충돌면의 형상에 따른 주파수 특성을 비교하고자 하였다. 이를 위해 충돌면이 제트의 직경보다 작은 원판(small plate)과 제트의 직경보다 큰 구멍(hole)의 2가지 경우에 대하여 실험을 하였고, 평판 충돌음에 대한 연구결과와 비교 검토하였다.

Thermoacoustic oscillation is a significant problem in cylindrical-type combustors such as common internal combustion engines, industrial furnaces, gas turbine, etc. This kind of low frequency oscillation can give rise to serious troubles such as the destruction of system or producing of a strong noise. Accurate numerical simulation of thermoacoustic phenomena is a complex and challenging problem. Especially, considering the reaction of mixture intensifies the difficulty of analysis. Like as other simulations of the aerodynamics and aeroacoustics, direct computation of thermoacoustic phenomena requires that the Navier-Stokes equations be solved using accurate numerical differentiation and time-marching schemes, with non-reflecting boundary conditions. In this study,, numerical approach aims at qualitative analysis and efficient prediction of problem, not at the development of an accurate scheme. Overally speaking, numerical prediction is reasonably matched with experimental result.

본 연구는 밀폐형 표면연소기의 모드해석 및 주파수특성의 실험을 통해 음향모드의 발생기구 및 발생조건을 구하기 위한 것이다. 연소장치의 치수변화와 부하, 당량비 등의 변화에 따른 진동특성의 변화를 실험하고 모드해석에 의한 예측결과와 비교고찰하여 음향모드의 특성을 밝혔다.

A new method is proposed for the isolation of resonances from scattered waves for acoustic wave resonance scattering problems. The resonance scattering function consisting purely of resonance information is defined. Acoustic wave scattering from a variety of submerged bodies is numerically analyzed. The classical resonance scattering theory (RST) and the new method compute identical magnitude of the resonance from each scattered partial wave, however, the phases are significantly different. The exact .pi.-radians phase shifts through the resonance and anti-resonance show that the proposed method properly extracts the vibrational resonance information of the scatterer. Due to the difference in the phase of each, partial wave, the new method and RST generate different total resonance spectra.

Most of large structures such as ship, airplane, and so on have internal structure home noise sources. The operation of the machineries results in vibration and noise of the structure. Particularly, the vibration of the machineries is transmitted to the far place from the sources and emits noise into the water or outdoor as well as the inner space of the structure. In the case of warships this emission into the water induces noise to reduce the performance of its underwater acoustic equipment. Therefore the structure home noise levels of the installed machineries are strictly limited. This paper shows examples of structure home noise reduction from machineries including pumps.

Radiation efficiency of a cylindrical shell whose surface vibrates under harmonic distribution is investigated by theoretical solutions and Boundary Element Method. The vibration modes of a cylindrical shell is determined from experiment and is compared with the result of Finite Element Method. Harmonic vibration response of the cylindrical shell under the point excitation and the radiation phenomena from its response is analyzed by Finite Element Method and Boundary Element Method.

Analogous problem for a gear dynamics where helical gears excite logitudinal forces in the shaft is studied. These shaft forces excite the supporting gear housing through bearing, causing structural vibration. In this study, shaft is modeled as a rod, and bearing is modeled by a massless spring. A simple model for gear housing is a clamped circular plate. To model this force transmission, the transfer functions from the shaft to a clamped circular plate are analytically derived by using the spectral method and four-pole parameter. Finally, radiated noise is computed, using the acoustic relations due to plate surface vibration.

본 논문에서는 마운트의 음향 강성계수를 실험적으로 구하기 위한 이론적 배경을 설명하고, 개발된 시험장치를 소개하였으며, 시험장치를 이용하여 구한 마운트의 음향 강성계수 측정결과를 수록하였다.

Cylindrical chamber silencers with an extended inlet and outlet are widely used to reduce the propagated noise in ducts in many application fields. In this study, an acoustic analysis is carried out for concentric extended pipes inserted into a simple expansion chambers An algebraic equation is derived by using the eigenfunction expansion and orthogonality principle. Using this analytical method, transmission losses are predicted for several configurations of the concentric extended systems.

As the concern for a global energy conservation and environmental protection are increasing, it has been more important thing to correspond with CFC depletion. Alternate refrigerants have merit such as lower global warming effect, but also have demerits such as lower efficiency, miscibility, increasing noise and poor reliability problems. Then we have to develop more efficient, silent and robust compressors to satisfying world-wide demand. In this paper, parametric study on rotary compressor muffler for a room air-conditioner was carried out to investigate the effect of important design variables on noise by using Taguchi robust design method with signal-to-noise(S/N) ratio. Taguchi method seems to be helpful for finding optimum value of design variables for noise level. We also applied neural network to find optimal value of design variables.

The specific noise level of 18 rotary compressor mufflers were measured and these data were analyzed by the Taguchi robust design method and the neural network. The optimal design value obtained by the neural network generally showed good agreement with that by the Taguchi method. The effects of eight important design variables on the specific noise level were discussed.

Acoustic performance of the absorptive mufflers used in air-conditioning and ventilating ducts, gas turbines, industrial fans influenced by the design parameters such as the length of mufflers, lining thickness, properties of the acoustic lining, and so forth. So we predicted the acoustic performance according to the design parameters. For the analysis, we assumed the radial propagation constant is locally reacted to the acoustic lining, and analyzed the acoustic performance based on the plane wave theory by using four-pole parameters.

Recently, TV makers have tried for high sound quality and power, However, due to the high power of the speaker the structure of set brings about a sound vibration problem. Therefore, this paper illustrates the sound vibration phenomenon for a monotype TV set and suggests guide lines for reducing the sound vibration in the design of TV sets,

A systematic procedure for designing a direct-radiator-type loudspeaker has been developed, based on a numerical vibro-acoustic analysis and the Taguchi method. The finite-element model of the speaker cone has been used to calculate the vibration response of the cone excited by the voice coil. The vibration response of the speaker cone has been used as a boundary condition for the acoustic analysis, and the acoustic frequency characteristics of the loudspeaker have been calculated by the boundary element method. The numerical model has been confirmed by comparing the numerical results with experimental ones obtained in an anechoic chamber. Some design parameters contributing dominantly to the acoustic characteristics have been selected by using the Taguchi method, and the variations of the acoustic characteristics due to the changes of the parameter values have been examined using the numerical model.

The noise sources in the outdoor unit of RAC(Room Air Conditioner) are identified by the sound intensity method. The main noise sources are compressor noise and fluid noise which is caused by the fan, heat exchanger and shroud. First, the fluid noise is reduced through the design ol new fan and shroud with high flow rate and low noise, reduction of the system resistance by rearrangement of heat exchanger, and optimization of the complex parameter between the fan and shroud. Next, in order to reduce the compressor noise, the new shape of compressor mount and sound-proof material was applied. As a result, the overall noise was reduced by 4-5dB(A).

This paper presents the analysis results of ex-core and in-core neutron noise, acceleration signals and pressure fluctuation measured at Ulchin Nuclear Unit 1 & 2 to identify and monitor the reactor internals vibration including fuel motion. A phase separation algorithm developed by authors was applied to the neutron noises to clearly identify the reactor internals vibratory motion. The beam mode frequency of the core support barrel was identified to be 8Hz and the shell mode to be 20Hz. The first frequency of the fuel assembly was also found to be 3Hz, while first two acoustic frequencies of the primary coolant system were 6 and 17.5Hz. By monitoring and analyzing these frequencies periodically, it is possible to diagnose the operating condition of reactor internals and to provide an early detection of faults for the predictive maintenance.

This study was performed to obtain a numerical model for a viscous fluid damper from an experimental testing. The input signals for displacement were chosen as two type : a triangular and a sinusoidal forms. The performing test parameters were the area of the resistant plate and the oil film thickness of the viscous fluid and the temperature effect was neglected. The numerical model was established by assuming to behavior as an non-Newtonian fluid. The test results were summarized by the equation of F = 0.0308A(V/d)$^{0.51}$25/. Using the obtainal formula, the procedure to apply the viscous damper for a real structure design was introduced..

Rubber has been widely used as a good device for reducing the vibration in various fields including the anti seismic device like LRB. The damping characteristic is needed to be mathematically modeled to predict the dynamic behavior of the isolated system. In this paper, The frequency response function was obtained experimentally by the resonant method and simulation was performed with the hysteretic model using the resonant test result. the hysteretic behavior of the rubber can be explained by the change of the static stiffness obtained in the DC by the concept of the transfer function.

Rubber materials are extensively used in various machine design application, mainly for vibration/shock/noise control devices. Over the years an enormous effort has been put into developing procedures to provide properties of rubber material for design function. However, there are still a lot of difficulties in the understanding of dynamic characteristics of the rubber components in compression. In this paper, the dynamic characteristics of rubber materials for anti-vibration under compression were investigated. Dynamic and static tests for rubber material with 3 different hardness were performed. In dynamic tests, non-resonance method, impedance method, was used to obtain the complex modulus (storage modulus and loss factor) and the effects of static pre-strain on the dynamic characteristics were investigated. Also, a relation equation between linear dynamic and nonlinear static behavior of rubber material was discussed and its usefulness to predict their combined effects was investigated.

Damping characteristics of ER dampers and flow rates inside ER valve with two different valve types were analyzed and compared with test results. Fluid flow inside ER valves was modeled by Bingham plastic model and Hagen-Poiseulli flow, while the equations of motion of total ER damper system were modeled by flow and hydraulic force balance. A general straight valve case was compared with a bended valve case which is newly tested for a possible improvement of ER damping force. As expected, the bended ER valve generates higher damping force and lower flow rates than the conventional straight ER valve due to additional flow restriction at the bended section. Analytical models of ER valve and ER damper generally predict reasonable performance characteristics of tested results. Therefore, developed analysis can be used for designing new ER dampers and simulation of ER semi-active suspension system as well.

Optical sensing techniques have been associated with high sensitivity and precise measurements and attracted considerable attention in recent years. In this paper, two channels TDM(Time Division Multiplexing) fiber-optic hydrophone array for the underwater applications was fabricated and their acoustic characteristics were investigated by using the acoustic water tank. A fiber length of the order of 100m is wounded at the hollow cylinder type aluminum mandrel. An unbalanced interferometer (discrete Mach-Zehnder type) was used. Sound detection performance is tested in the underwater tank with 2kHz continuous sound source. Finally, it is shown that two channels TDM(Time Division Multiplexing) fiber-optic hydrophone array can detect 2kHz sound stably.

The SONAR(SOund NAvigation and Ranging) is the system that detects objects and finds their locations in water by using the echo ranging technique. In this paper, the scattering phenomena for a rigid spherical scatterer will be analyzed using closed form solution, Boundary Element Method and Finite Element Method. Scattering analysis for an elastic spherical scatterer will be analyzed, later. In oder to analyzing the sound wave scattering phenomena for an elastic scatterer in water coupled problem between acoustic and vibration must be considered.

본 연구에서는 연성손실계수가 구조물의 진동에 미치는 영향을 살펴보았다. 세부시스템의 두께가 동일할 경우 평판으로 이루어진 구조물이 접수되면 연성손실계수가 감소하게 된다. 특히, 저주파수 대역에서 연성손실계수가 크게 낮아졌다. 그 주된 원인은 접수로 인해 평판에서 전파되는 굽힘파의 그룹속도가 줄어들기 때문이며, 접수로 인한 파워투과계수의 변화는 크지 않았다. 내부에 격벽을 가진 steel box에 공기중 연성손실계수와 접수시 연성손실계수를 적용하여 세부시스템의 속도를 구한 결과, 공기중 연성손실계수를 이용하여 구한 속도가 접수시 연성손실계수를 이용하여 구한 속도보다 약 2-3 dB정도 높게 나타났다. 선박과 같은 복잡한 구조물인 경우 연성손실계수에 의한 속도 차이는 더욱 커질 것으로 추정된다. 따라서, SEA를 이용한 접수 구조물의 진동해석에서 해석오차를 줄이기 위해서는 연성손실계수에 접수의 영향을 고려해 주어야 함을 확인하였다. 특히, 접수효과가 고려된 연성손실계수를 사용하면 SEA가 큰 오차를 보이는 중, 저주파수 대역에서 해석 결과에 대한 신뢰성을 높일 것으로 판단된다.

This paper deals with the analytical model of an elastic porous material in sound transmission loss of a double panel with fiber glasses. From the parametric analysis, it is concluded that the boundary condition, which is concerned to the contact between the skin panel and core materials, does not have much influence on sound transmission loss of a double panel with fiber glasses, and material properties of the porous material become, however, important factors to mass-spring-mass resonance. The comparisons of the prediction with the measurement of sound transmission loss of walls show good agreement between the two values.

This paper is to compare the absorption coefficient with normal incidence waves and it with diffuse incidence waves of glass wool which the most used absorption material and multi layer fiber. The absorption coefficient with normal incidence waves is calculated by surface impedance that measured by using an acoustic tube. Based on this data, the absorption. coefficient with diffuse incidence waves is predicted and is compared with measured the absorption coefficient in reverberation room.

The pressure level and the insertion loss at the receiving point behind finite length noise barriers are measured in an anechoic room by scale model test. The measured sound pressure level which are conducted under the several experimental conditions such as the length of the noise barrier, the distance between the noise barrier and the receiving point, the number of noise barriers, and the existence of the reflective building behind receiving point) and the insertion loss of a noise barrier having simple shape are well agreed with theoretical calculation which is based on Lam's model.

To measure the absorption ratio and the transmission loss of a material, a usage of the reverberation room has been popular. However, the reverberation room is expensive to build it and, sometimes, test procedure is not easy. Therefore, to get the data of absorption ratio, several possible technologies has been proposed using the tube. Among these technologies, with the analysis of the spectral density, a convenient method has been introduced to measure both the absorption ratio and transmission loss. The measured data has been compared with the results of the measurement at the reverberation room.

This research is concerned with the active vibration controller design for smart structures by a modified LQG controller. The smart structure is defined as the structure equipped with smart actuators and sensors. Various analog and digital control, techniques aimed for the piezoceramic sensors and actuators have been proposed for the active vibration control of smart structures. In this paper, the modified LQG controller is developed for the active vibration suppression of smart structures to implement the predefined decay rate on modal displacements. The proposed modified LQG controller proved its effectiveness by experiments.

Many of the adaptive noise control systems utilize a form of the least mean square (LMS) algorithm. In the active control of noise, it is common practice to locate an error microphone far from the control source to avoid the near-field effects by evanescent waves. Such a distance between the control source and the error microphone makes a certain level of time-delay inevitable and, hence, may yield undesirable effects on the convergence properties of control algorithms such as filtered-x LMS. This paper discusses the dependence of the convergence rate on the acoustic error path in these popular algorithms and introduces new algorithms which increase the convergence region regardless of the time-delay in the acoustic error path. Performances of the new LMS algorithms are presented in comparison with those by the conventional algorithms based on computer stimulations and experiments.

Combustion instability by thermoacoustic feedback incite strong low frequency noise and vibration which damage the system and provoke the environmental problems. Therefore, it is necessary to control the thermoacoustic oscillation. In the way of controlling the instability, active control method using adaptive algorithm is applied. In this study, active noise control method using anti-sound technique is selected, whose principle is cancelling the noise with the addition of opposite phase sound. At first, simulation is performed to confirm the stability of controller, and after that control of combustion instability is carried out to get cancellation of 20-30dB SPL.

Optimization of the collocated piezoceramic sensor/actuator placement is investigated numerically and verified experimentally for vibration control of laminated composite plates. The finite element method is used for the analysis of dynamic characteristics of the laminated composite plates with the piezoceramic sensor/actuator. The structural damping index(SDI) is defined from the modal damping. It is chosen as the objective function for optimization. Weights for each vibrational mode are taken into account in the SDI calculation. The gradient method is used for the optimization. Optimum location of the piezoceramic sensor/actuator is determined by maximizing tie SDI. Numerical simulation and experimental results show that the optimum location of the piezoceramic sensor/actuator is dependent upon the outer layer fiber orientations of the plate, and location and size of the piezoceramic sensor/actuator.

이 글의 구성은 다음과 같다. 1. ISO의 개관 2. ISO의 조직 3. 국내현황 4. TC 43의 관련분야 5. TC 43의 관련규격

ISO(the International Organization for Standardization) is a worldwide federation of national standards bodies, from some 120 countries. The technical work of ISO is highly decentralized, carried out in a hierarchy of some 2,700 technical committees(TC), sub-committees(SC) and working groups(WG). The results of the ISO work are published as International Standards. In this paper, main fields of work at the ISO/TC43/SCI are described.

ISO/TC 43/SC 2(Building Acoustics)은 음향기술위원회의 건축음향분과로서 건축음향관련 규격을 제정하거나 개정하고 관련규격을 검토하는 운영위원회이다. ISO/TC 43/SC 2의 운영범위와 최근의 활동상황을 개괄적으로 소개하고자 한다.

An automated calibration system of sound level meters was developed and tested. As a standard sound source, the speaker unit(Forstex FE208) cabineted by 440 * 390 * 490 mm$^{3}$(LHW) volume wood box was adopted. Including this source, the driving part was found out to have a good linearity of sound pressure output vs AC input. We use the Hybrid-Bisect, /Newton-Raphson method modified by the linearity as searching algorithm. Personal computer and program do the control, measurements, and calculations and finally do the accumulation of useful data and results. Several trials of automatic calibration using this developed system give reliable results.

본 논문에서 추구하는 내용과 목표는 현실적인 필요성에도 불구하고 그의 과학적이고 객관적인 규명을 위한 연구가 미진했던 것이 사실이다. 가장 큰 이유는 비교적 단기간에 할 수 있는 소음의 각종 물리적 특성에 대한 연구와는 달리 소음과 생명(인체 및 동물) 사이의 관계에 대한 연구는 장기간 노력이 필요하기 때문이다. 이러한 의미에서 이 논문은 이 분야에 대한 국내의 연구노력에서 중요한 시발점이 되고 있다고 믿는다. 무엇보다도 소음에 의한 인체피해와 가축피해의 인과관계를 규명하여 피해량 산출의 근거를 마련한 것은 큰 의미가 있다고 생각한다. 물론, 이들 결과는 현재로서는 객관적 처리가 가능한 요소들만을 바탕으로 하고 있고, 앞으로 계속 보완되어야 할 여지는 있지만, 현장 조사에 따른 여러 가지 사회적 혹은 인간적 요소들이 적절히 반영되어 종합적으로 고려될 때 소음 피해분쟁 해결에 만족할 수준의 체계성과 일관성을 유지할 수 있으리라고 기대한다.

본 연구는 도시 인근발전소의 소음 유발 기기에 의한 환경소음의 실제적인 기여도를 평가하고 더욱 쾌적한 환경조성방안을 도출하기 위하여 수행되었다. 발전소 경계의 수음자소음을 기초로 각종 기기의 주파수 분석을 통하여 소음 유발 기기를 규명하고 소음원의 주 주파수 및 크기를 구하였다. 소음원의 전파경로를 파악하기 위해 소음레벨의 분포도를 구하였으며, 측정치와도 잘 일치함을 보여주었다.

Aircraft noise is one of the main causes of environmental impact. It is more serious than any other noise nuisance. It has become an increasing source of annoyance to the large number of people who live in communities near airports. This paper demonstrates the prediction of aircraft noise using Integrated Noise Model(INM) 5.1 developed by U.S. FAA and aircraft noise contour map near airports.

Acoustic performance of DICT's acoustic laboratory was evaluated. As a result, background noise and inverse squre law of an anechoic room were satisfied with ISO 3745 standard value. Also, reverberation time and standard deviation of sound pressure level distribution in reverberation rooms were within maximum error limit that was ruled on ISO 3741.

A severe noise in industrial field can be sometimes generated from unexpected installation error and misunderstanding of industrial machinery. To solve the noise problem, the diagnostic tool is generally applied to identify the noise source and to detect the fault of machinery. And then, the suitable control countermeasure corresponding to the diagnostic results is presented. In this paper, two control cases an noise problem of the Incineration Plant and the Pump are introduced.

SONICS is the software developed by authors. The program provides the noise level in outdoors due to various noise source types : construction machines including blast sources, railroad vehicles and automobiles. h operates in the Windows system. Since the software is compiled by using Visual C++ 4.0, users can run the program interactively. Also SONICS uses Windows' dialog-box and choice-button so that a novice user can easily implement the program for the environmental noise planning.

이 글에서 살펴본 바의 내용에 의하면 철도차량 습식 바닥구조의 차음성능은 기존의 35 mm를 47 mm로 하는 경우 약 4dB 정도의 차음개선 효과를 기대할 수 있으며, 제진층을 추가로 도입하는 경우 1~2dB의 추가적인 차음개선을 기대할 수 있다고 결론된다. 바닥충격음에 대한 차단성능은 경량충격음의 경우 두께 증가 및 제진층 적용에 의하여 각각 3dB 및 7dB의 차음개선이 예상된다. 그러나 중량충격음의 경우에는 차음개선 효과가 거의 없으며 오히려 감소하는 경우도 있으므로 보다 구체적인 검토 연구의 필요성이 있다.산업계에서는 현재의 진동소음저감기술을 좀더 단시간에 차량개발 프로그램에 적용하는데 더욱 큰 노력을 할 필요가 있을 것이다. 따라서 여기에서는 현재 자동차업체에서 수행하는 진동, 소음및 충격시험평가에 대해서만 국한하여 기술하고자한다.urce)을 찾아 직접 그 원인을 차단 및 치유하는 적극적이고 공격적인 방법을 이용하고있다. 본 글에서는 이러한 진동소음 문제를 차량의 개발 단계에서 해결하기 위한 일련의 과정 및 여러가지 개선기법에 대해서 살펴보고 그를 통한 진동소음 문제 해결방법을 제시하고자 한다.