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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers A
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 26, Issue 12 - Dec 2002
Volume 26, Issue 11 - Nov 2002
Volume 26, Issue 10 - Oct 2002
Volume 26, Issue 9 - Sep 2002
Volume 26, Issue 8 - Aug 2002
Volume 26, Issue 7 - Jul 2002
Volume 26, Issue 6 - Jun 2002
Volume 26, Issue 5 - May 2002
Volume 26, Issue 4 - Apr 2002
Volume 26, Issue 3 - Mar 2002
Volume 26, Issue 2 - Feb 2002
Volume 26, Issue 1 - Jan 2002
Selecting the target year
A Study of New Evolutionary Approach for Multiobjective Optimization
Shim, Mun-Bo ; Suh, Myung-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 987~992
DOI : 10.3795/KSME-A.2002.26.6.987
In an attempt to solve multiobjective optimization problems, many traditional methods scalarize the objective vector into a single objective. In those cases, the obtained solution is highly sensitive to the weight vector used in the scalarization process and demands the user to have knowledge about the underlying problem. Moreover, in solving multiobjective problems, designers may be interested in a set of Pareto-optimal points, instead of a single point. In this paper, pareto-based Continuous Evolutionary Algorithms for Multiobjective Optimization problems having continuous search space are introduced. This algorithm is based on Continuous Evolutionary Algorithms to solve single objective optimization problems with a continuous function and continuous search space efficiently. For multiobjective optimization, a progressive reproduction operator and a niche-formation method fur fitness sharing and a storing process for elitism are implemented in the algorithm. The operator and the niche formulation allow the solution set to be distributed widely over the Pareto-optimal tradeoff surface. Finally, the validity of this method has been demonstrated through a numerical example.
Analysis of Inclined Crack Extension in Orthotropic Solids Under Biaxial Loading
Lim, Won-Kyun ; Choi, Seung-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 993~1000
DOI : 10.3795/KSME-A.2002.26.6.993
The objective of this work is to develop the capability to analyze accurately the mixed-mode propagation of a crack in composite structures with elastic orthotropic material stiffness properties and anisotropic material strength characteristics. In order to develop the capability to fully analyze fracture growth and failure in anisotropic structures, we examined the fundamental problem of mixed mode fracture by carrying out the analysis on orthotropic materials with an inclined crack subject to biaxial loading. Our goal here is to include an additional term in the asymptotic expansion of the crack tip stress field and to show that the direction of crack initiation can be significantly affected by that term. We employ the normal stress ratio theory to predict the direction of crack extension. It is shown that the angle of crack extension can be altered by horizontal loads and the use of second order term in the series expansion is important f3r the accurate determination of crack growth direction.
Pyroelectric Peyformance Evaluation of Pure PZT and Alternately Deposited PZT/PT Thin Films
Ko, Jong-Soo ; Kwak, Byung-Man ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1001~1007
DOI : 10.3795/KSME-A.2002.26.6.1001
To improve the performance of the PZT thin flms, each PZT and PT layer was alternately deposited on a Pt/Ti/Si
/Si substrate by a modified sol-gel solid precursor technique. For comparison, PZT thin films were also prepared with an identical method under the same conditions. XRD measurement revealed that the diffraction pattern of the multilayer film was due to the superimposition of the PZT and PT patterns. At 1㎑, a dielectric constant of 389 and 558, a dielectric loss of 1.2% and 1.1% were obtained for the PZT/PT and PZT thin films, respectively. If we consider the PT dielectric constant to be 260, it is clear that the dielectric constant of alternately deposited PZT/PT thin films was well adjusted. The PZT/PT thin film showed a low dielectric constant and a similar dielectric loss compared with those of the PZT film. The figures of merit on detectivity for the PZT/PT and PZT thin films were 20.3
/, and 18.7
/, and the figures of merit on voltage response were 0.038㎡/C and 0.028 ㎡/C, respectively. The high figures of merit for the PZT/PT film were ascribed to its relatively low dielectric constant when compared to the PZT thin films.
An Enhanced Genetic Algorithm for Global and Local Optimization Search
Kim, Young-Chan ; Yang, Bo-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1008~1015
DOI : 10.3795/KSME-A.2002.26.6.1008
This paper proposes a combinatorial method to compute the global and local solutions of optimization problem. The present hybrid algorithm is the synthesis of a genetic algorithm and a local concentrate search algorithm (simplex method). The hybrid algorithm is not only faster than the standard genetic algorithm, but also gives a more accurate solution. In addition, this algorithm can find both the global and local optimum solutions. An optimization result is presented to demonstrate that the proposed approach successfully focuses on the advantages of global and local searches. Three numerical examples are also presented in this paper to compare with conventional methods.
A Study on the Measurement of the Fluid Viscosity by Using the Torsional Vibration of a Circular Rod
Chun, Han-Yong ; Kim, Jin-Oh ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1016~1025
DOI : 10.3795/KSME-A.2002.26.6.1016
This paper deals with the measurement of the fluid viscosity by using the torsional vibration of a circular rod excited by a torsional vibrator at one end. The effect of an adjacent viscous fluid on the torsional vibration of the rod has been studied theoretically and expressed in terms of the mechanical impedance. The theoretically-obtained trend that the mechanical impedance is proportional to the square root of the viscosity times the density of the fluid has been confirmed by the impedance measurement. The paper demonstrates that a torsionally-vibrating rod can be used as a sensor to measure the viscosity of a fluid.
Machining Simulation Program for Symmetric Rotors in Screw Compressor as Wrap Angle
Kim, Yeon-Su ; Choi, Boo-Hee ; Park, Jae-Min ; Choi, Sang-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1026~1034
DOI : 10.3795/KSME-A.2002.26.6.1026
This paper describes the development of machining simulation program which is able to design cutter profile and 3-dimensional geometry for rotors in screw compressor. Based on the symmetric rotor profiles developed previously, cutters are designed and 3-dimensional geometries of rotors are generated by using simulation program. Symmetric rotors are manufactured by a universal milling machine, and surface geometries of them are measured by a 3-dimension scanner It is shown that simulation program developed is useful to design cutter for rotor manufacturing and to generate the 3-dimensional helicoid geometry of rotor in screw compressor.
Stability Analysis of Time Delay Controller for General Plants
Kwon, Oh-Seok ; Chang, Pyung-Hun ; Jung, Je-Hyung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1035~1046
DOI : 10.3795/KSME-A.2002.26.6.1035
Time Delay Control(TDC) is a robust nonlinear control scheme using Time Delay Estimation(TDE) and also has a simple structure. To apply TDC to a real system, we must design Time Delay Controller to guarantee stability. The earlier research stated sufficient stability condition of TDC for general plants. In that research, it was assumed that time delay is infinitely small. But, it is impossible to implement infinitely small time delay in a real system. So, in this research we propose a new sufficient stability condition of TDC for general plants with finite time delay. And the simulation results indicate that the previous sufficient stability condition does not work even for small time delay, while our proposed condition works well.
Fabrication and Fracture Properties of Nb/MoSi
Lee, Sang-Pill ; Yoon, Han-Ki ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1047~1052
DOI : 10.3795/KSME-A.2002.26.6.1047
The impact value, the interfacial shear strength, the tensile strength and the fracture strain of Nb/MoSi
laminate composites, which were associated with the interfacial reaction layer, have been investigated. Three types of Nb/MoSi
laminate composites alternating sintered MoSi
layers and Nb foils were fabricated as the parameter of hot press temperature. The thickness of interfacial reaction layer of Nb/MoSi
laminate composites increased with increasing the fabrication temperature. The growth of interfacial reaction layer increased the interfacial shear strength and led to the decrease of impact value in Nb/MoSi
laminate composites. It was also found that in order to maximize the fracture energy of Nb/MoSi
laminate composites, interfacial shear strength and the thickness of interfacial reaction layer must be secured appropriately.
The Machining Technique of Connecting Rod through Constant Control of Cutting Speed Method in Ball End Mill Machining
Kang, Myung-Chang ; Jung, Young-Ho ; Kim, Jeong-Suk ; Moon, Sung-Jun ; Kim, Kyung-Kyoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1053~1059
DOI : 10.3795/KSME-A.2002.26.6.1053
The purpose of this study is to suggest how the machining technique of constant control of cutting speed can improve precision machining and tool life in high speed machining using a ball end mill. Cutting speed is changed in machining fee form surfaces such as connecting rod die. So, we don`t have supreme surface form and tool life on machining. To solve this problem we should settle on optimal cutting speeds in free form surface machining. And, to improve precision machining, We must execute high speed machining methods to output optimum NC data using developed constant control of cutting speed program after modeling by CAD/CAM. In this paper, a comparison was made of the cutting precision and tool life in conventional cutting and those in connecting rod machining applying the program developed.
Development of CVTs Composed of a 2K-H I Type Differential Gear Unit and a V-belt Drive
Kim, Yeon-Su ; Choi, Sang-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1060~1068
DOI : 10.3795/KSME-A.2002.26.6.1060
Compound continuously variable transmission(CVT) mechanisms are proposed, which can offer a backward mode, a geared neutral, an underdrive mode and an overdrive mode. They are composed of a 2K-H I type differential gear unit, a V-belt type continuously variable unit(CVU), a few friction clutches and gears, and not required of a starting device as a torque converter. Compound CVT mechanisms developed here present two distinct operating modes which are a power circulation mode and a power split mode. The transition of two modes takes place at the particular CVU speed ratio. For these CVT mechanisms, performance analysis related to speed ratio, power ratio and efficiency are executed and proven by experimental studies.
Evaluation on the Creep Life Prediction Using Initial Strain Method
Kong, Yu-Sik ; Lim, Man-Bae ; Lee, Sang-Pill ; Yoon, Han-Ki ; Oh, Sae-Kyoo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1069~1076
DOI : 10.3795/KSME-A.2002.26.6.1069
The high temperature creep behavior of heat machine systems such as aircraft engines, boilers and turbines in power plants and nuclear reactor components have been considered as an important and needful fact. There are considerable research results available for the design of high temperature tube materials in power plants. However, few studies on the Initial Strain Method (ISM) capable of securing repair, maintenance, cost loss and life loss have been made. In this method, 3 long time prediction Of high temperature creep characteristics can be dramatically induced through a short time experiment. The purpose of present study is to investigate the high temperature creep lift of Udimet 720, SCM 440-STD61 and 1Cr-0.5Mo steel using the ISM. The creep test was performed at 40
under a pure loading. In the prediction of creep life for each materials, the equation of ISM was superior of Larson-Miller Parameter(LMP). Especially, the long time prediction of creep life was identified to improve the reliability
Optimum Tool Design in a Multi-stage Rectangular Cup Drawing and Ironing Process with the Large Aspect Ratio by the Finite Element Analysis
Kim, Se-Ho ; Kim, Seung-Ho ; Huh, Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1077~1084
DOI : 10.3795/KSME-A.2002.26.6.1077
Optimum tool design is carried out fur a multi-stage rectangular cup deep-drawing and ironing process with the large aspect ratio. Finite element simulation is carried out to investigate deformation mechanisms with the initial design made by an expert. The analysis considers the deep drawing process with ironing for the thickness control in the cup wall. The analysis reveals that the difference of the drawing ratio within the cross section and the irregular contact condition produce non-uniform metal flow to cause wrinkling and severe extension. For remedy, the modification guideline is proposed in the design of the tool and the process. Analysis results confirm that the modified tool design not only improves the quality of a deep-drawn product but also reduces the possibility of failure. The numerical result shows fair coincidence with the experimental one. After tryouts of the tool shape, the rectangular cup has been produced in the transfer press.
Analysis of a Vehicle Performance Using Taguchi Method: How does a Torque Converter Affect the Vehicle Performance\ulcorner
Lee, Chin-Woo ; Lim, Won-Sik ; Park, Yeong-Il ; Lee, Jang-Moo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1085~1091
DOI : 10.3795/KSME-A.2002.26.6.1085
General vehicle is evaluated by its acceleration, fuel economy, NVH (Noise, Vibration and Harshness) and subjective (such as launching feel) performance. The first step to enhance its performance is to know how much each component affects on the vehicle performance. It is very important to know what is the key factor of the component among many specifications. Hydraulic torque converter can be expressed by means of its performance curve (torque ratio and capacity factor). In this paper, the key factor of torque converter, which affect vehicle performance, are explored by using Taguchi method. Moreover, general sensitivity analysis method is compared with Taguchi`s experiment.
Adaptive Learning Control of Neural Network Using Real-Time Evolutionary Algorithm
Chang, Sung-Ouk ; Lee, Jin-Kul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1092~1098
DOI : 10.3795/KSME-A.2002.26.6.1092
This paper discusses the composition of the theory of reinforcement teaming, which is applied in real-time teaming, and evolutionary strategy, which proves its the superiority in the finding of the optimal solution at the off-line teaming method. The individuals are reduced in order to team the evolutionary strategy in real-time, and new method that guarantee the convergence of evolutionary mutations are proposed. It is possible to control the control object varied as time changes. As the state value of the control object is generated, applied evolutionary strategy each sampling time because of the teaming process of an estimation, selection, mutation in real-time. These algorithms can be applied, the people who do not have knowledge about the technical tuning of dynamic systems could design the controller or problems in which the characteristics of the system dynamics are slightly varied as time changes. In the future, studies are needed on the proof of the theory through experiments and the characteristic considerations of the robustness against the outside disturbances.
An Engineering Method for Non-Linear Fracture Mechanics Analysis of Circumferential Through-Wall Cracked Pipes Under Internal Pressure
Huh, Nam-Su ; Kim, Yun-Jae ; Kim, Young-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1099~1106
DOI : 10.3795/KSME-A.2002.26.6.1099
This paper provides engineering J-integral and crack opening displacement (COD) estimation equations for circumferential through-wall cracked pipes under internal pressure and under combined internal pressure and bending. Based on selected 3-D finite element calculations for the circumferential through-wall cracked pipes under internal pressure using the idealized power law materials, the elastic and plastic influence functions for fully plastic J-integral and COD solutions are found as a function of the normalized crack length and the mean radius-to-thickness ratio. These developed GE/EPRI-type solutions are then re-formulated based on the enhanced reference stress method. Such re-formulation not only provides simpler equations for J-integral and COD estimations, but also can be easily extended to combined internal pressure and bending. The proposed equations are compared with elastic-plastic finite element results using actual stress-strain data, which shows overall excellent agreement.
The Characteristics of the Hydrogen Embrittlement for the Cr-Mo Steels in Use of Pressure Vessel
Lee, Hwi-Won ; Yang, Hyun-Tae ; Kim, Sang-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1107~1113
DOI : 10.3795/KSME-A.2002.26.6.1107
This study presents the hydrogen emblittlement in the metal, which decreases the ductility and then induces the brittle fracture. The contribution deals with the effect of strain rate and notch geometry on hydrogen emblittlement of 1.25Cr-0.5Mo and 2.25Cr-1Mo steels, which are in use at high pressure vessel. Smooth and notched specimens were examined to obtain the elongation and tensile strength. For charging the hydrogen in the metal, the cathodic electrolytic method was used. In this process, current density is maintained constant. The amount of hydrogen penetrated in the specimen was detected by the hydrogen determenator(LECO RH404) with the various charging time. The distribution of hydrogen concentration penetrated in the specimen was obtained by finite element analysis. The amount of hydrogen is high in smooth specimen and tends to concentrate in the vicinity of surface. The elongation and tensile strength decreased with the passage of charging time in 1.25Cr-0.5Mo and 2.25Cr-1Mo steels. The elongation increased and tensile strength decreased as strain rate increased. As a result of this study, it is supposed that 1.25Cr-0.5Mo steel is more sensitive than 2.25Cr-lMo steel in hydrogen embrittlement. Hydrogen embrittlement susceptibility of notched specimen after hydrogen charging is more remarkable than that of smooth specimen.
Design of the Well-Conditioned Observer Using the Non-Normality Measure
Jung, Jong-Chul ; Huh, Kun-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1114~1119
DOI : 10.3795/KSME-A.2002.26.6.1114
In this paper, the well-conditioned observer is designed to be insensitive to the ill-conditioning factors in transient and steady-state observer performance. A condition number based on 12-norm of the eigenvector matrix of the observer matrix has been proposed on a principal index in the observer performance. For the well-conditioned observer design, the non-normality measure and the observability condition of the observer matrix are utilized. The two constraints are specified into observer gain boundary region that guarantees a small condition number and a stable observer. The observer gain selected in this region guarantees a well-conditioned and observable property. In this study, this method is applied to the Luenberger observer and Kalman filters for small order systems. In designing Kalman filters, the ratio of the process noise covariance to the measurement noise covariance is a design parameter and its effect on the condition number is investigated.
Machining Characteristics of Tool Steels Manufactured by Electro Slag Casting Process
Kim, Jung-Woon ; Kim, Bong-Joon ; Lee, Deug-Woo ; Moon, Young-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1120~1126
DOI : 10.3795/KSME-A.2002.26.6.1120
Machining characteristics of tool steels manufactured by electro slag casting process has been investigated in this study. For the estimation of machinability, turning and drilling tests are carried out. The chip shapes at various velocities are investigated for the comparison of turning workabilities of tool steels because the chip shapes reflect characteristics of cutting resistance. In case of drilling test, feed motor currents measured by a hall sensor are used as a measure for the drilling resistance. The machining characteristics of the tool steels are strongly correlated with tensile properties, such as tensile strength, hardness, and ductility. In case of turning workability, it was found to be favoured by the higher tensile strength, while the opposite is true far the drilling workability. The electro-slag casted materials show better turning workability in the viewpoint of chip shapes and, the quenching-tempered electro-slag casted material has relatively better drilling machinability than that of the annealed one.
Engineering Elastic-Plastic Fracture Analysis for Semi-Elliptical Surface Cracked Plates Under Combined Bending and Tension
Shim, Do-Jun ; Kim, Yun-Jae ; Choi, Jae-Boong ; Kim, Young-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1127~1134
DOI : 10.3795/KSME-A.2002.26.6.1127
The present paper provides an engineering J estimation equation for surface cracked plates under combined bending and tension. The proposed equation is based on the reference stress approach, and the most relevant normalising loads to define the reference stress for accurate J estimations are given for surface cracked plates under combined bending and tension. Comparisons with J results from extensive 3-D FE analyses, covering a wide range of crack geometry, plate geometry and loading combination, show overall good agreement not only at the deepest point but also at arbitrary points along the crack front. for pure tension, agreement between the estimated J and the FE results is excellent, even at the surface point. On the other hand, for pure bending and combined bending and tension, the estimated J values become less accurate for locations close to the surface point. Thus the results in this paper will be useful to assess short-term fracture or low cycle fatigue of surface defects in plates under combined bending and tension.
A Study on Construction of Synchronous Control System for Extension and Stability
Byun, Jung-Hoan ; Kim, Young-Bok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1135~1142
DOI : 10.3795/KSME-A.2002.26.6.1135
In this study, a methodology of synchronous control which can be applied to position synchronization of a multi-axes driving system has been developed. The synchronous error is caused by model uncertainties and disturbance at each axis. To overcome these problems, the synchronous control system of each axis has been composed of reference model, speed and synchronous controllers. The speed control system has been designed to follow speed reference. And the synchronous controller has been designed to keep minimizing the position synchronous error by reference model and H
/ approach. By the proposed method, position synchronous control system can be easily extended to two or more axes driving system. The effectiveness of the proposed method has been demonstrated by experiment.
Interactions of Spherical Acoustic Shock Waves with a Spherical Elastic Shell near a Free-Surface
Lee, Min-Hyung ; Lee, Beom-Heon ; Lee, Seung-Yop ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1143~1148
DOI : 10.3795/KSME-A.2002.26.6.1143
This paper analyses the transient response of a spherical elastic shell located near fee surface and impinged by spherical step-exponential acoustic shock waves. The problem is solved through extension of a method (Huang, 1969) previously formulated for the excitation in an infinite domain, which employs the classical separation of variables, series solutions, and Laplace transform technique The effect of the free surface reflection is taken into account using the image source method. The reflection of the incident wave has been treated by the same image formulation. If the reflection of the pressure field scattered and radiated by the shell is considered, the problem becomes that of multiple scattering by two spheres. However, this is in general negligible considering errors inherent from other sources and that the scattered and radiated pressure waves emanating from the shell are small. Thus, the problem is reduced to that of a structure immersed in an infinite fluid and impinged upon the origin and the image incident.
Analysis of Power Characteristics for a Hydromechanical Transmission Considering HSU Flow Loss
Sung, Duk-Hwan ; Lee, Geun-Ho ; Kim, Hyoung-Eui ; Kim, Hyun-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1149~1158
DOI : 10.3795/KSME-A.2002.26.6.1149
An improved hydrostatic unit(HSU) model is proposed by considering the flow loss in order to analyze the power flow characteristics of a hydromechanical transmission(HMT) and a network analysis algorithm is presented to determine the torque and speed of each element of the HMT. To calculate the torque and flow loss of a pump and a motor in HSU, an effort and flow concept is introduced, which can be used to establish a torque and speed matrix in the network analysis. It is found from the network analysis that magnitude of the HSU stroke increases to maintain the same output speed in order to compensate the flow Boss in the HSU and the efficiency of the HMT shows the lowest value in the 1st speed since the HSU has the largest flow loss in the 1st speed and the flow loss decreases as the speed ratio upshifts.
Investigation about the Wear Characteristics of Nylon Pinions Against Steel Gears by SEM
Kim, Choong-Hyun ; Ahn, Hyo-Sok ; Chong, Tae-Hyong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1159~1168
DOI : 10.3795/KSME-A.2002.26.6.1159
Power-transmission Nylon pinions against steel gears fur different pitch line velocities was studied with a power circulating gear test rig under unlubricated condition by SEM(Scanning Electron Microscope). The wear characteristics of Nylon pinions varied significantly with the pitch line velocity and applied load. Wear occurred most severely at the regions including pitch circle and root circle of Nylon pinions. It is confirmed that Nylon pinions are able to be used fer power-transmission under limited conditions.
Eigenvalue Analysis of Circular Mindlin Plates Using the Pseudospectral Method
Lee, Jin-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1169~1177
DOI : 10.3795/KSME-A.2002.26.6.1169
A study of fee vibration of circular Mindlin plates is presented. The analysis is based on the pseudospctral method, which uses Chebyshev polynomials and Fourier series as basis functions. It Is demonstrated that rapid convergence and accuracy as well as the conceptual simplicity could be achieved when the pseudospectral method was apt)lied to the solution of eigenvalue problems. Numerical examples of circular Mindlin plates with clamped and simply supported boundary conditions are provided for various thickness-to-radius ratios.
Analysis of New Air Control System in Clean Stocker(II)
Choi, Gi-Han ; Han, Chang-Woo ; Lee, Sang-Ryong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1178~1186
DOI : 10.3795/KSME-A.2002.26.6.1178
Clean stockers are being used by semiconductor and TFT-LCD manufacturers to store and buffer work in process. The only way to keep the stored product clean is to provide constant clean airflow the product and through stocker. Up to now, stockers typically have been configured to receive their laminar airflow from fan filter units that are located on the side of the stocker. This type of stocker may have such problems as complexity of structure, increment of temperature, mechanical vibration, initial investment and running cost. In this study, in order to solve the above mentioned problems, new air control system in stocker is proposed, which is to control open ratios of exits that are located on the side of the stocker without fan filter units. In this study, static pressure regain was used for the analysis of the open ratios of exits theoretically and experiment was also conducted using actual clean stocker for TFT-LCD manufacturers and CFDesign, was used for simulating airflow in stocker. As a result, open ratios of exits can be obtained by the analysis of static pressure regain and was verified by experiment and simulation results. Therefore, new air control system in stocker can be used by the semiconductor and TFT-LCD manufacturers.
Measurement of Glass-Silicon Interfacial fracture Toughness and Experimental Evaluation of Anodic Bonding Process based on the Taguchi Method
Kang, Tae-Goo ; Cho, Young-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1187~1193
DOI : 10.3795/KSME-A.2002.26.6.1187
Anodic bonding process has been quantitatively evaluated based on the Taguchi analysis of the interfacial fracture toughness, measured at the interface of anodically bonded silicon-glass bimorphs. A new test specimen with a pre-inserted blade has been devised for interfacial fracture toughness measurement. A set of 81 different anodic bonding conditions has been generated based on the three different conditions for four different process parameters of bonding load, bonding temperature, anodic voltage and voltage supply time. Taguchi method has been used to reduce the number of experiments required for the bonding strength evaluation, thus obtaining nine independent cases out of the 81 possible combinations. The interfacial fracture toughness has been measured for the nine cases in the range of 0.03∼6.12 J/㎡. Among the four process parameters, the bonding temperature causes the most dominant influence to the bonding strength with the influence factor of 67.7%. The influence factors of other process parameters, such as anodic voltage and voltage supply time, bonding load, are evaluated as 18%, 12% and 2.3%, respectively. The maximum bonding strength of 7.23 J/㎡ has been achieved at the bonding temperature of 460
with the bonding load of 45gf/㎠, the applied voltage of 600v and the voltage supply time of 25minites.
Topology Optimization of the Primary Mirror of a Multi-Spectral Camera
Park, Kang-Soo ; Chang, Su-Young ; Lee, Eung-Shik ; Youn, Sung-Kie ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1194~1202
DOI : 10.3795/KSME-A.2002.26.6.1194
A study on the topology optimization of a multi-spectral camera for space-use is presented. The optimization is carried out under self-weight and polishing pressure loading. A multi-spectral camera for space-use experiences degradation of optical image in the space, which can not be detected on the optical test bench on the earth. An optical surface deformation of a primary mirror, which is a principal component of the camera system, is an important factor affecting the optical performance of the whole camera system. In this study, topology optimization of the primary mirror of the camera is presented. As an objective function, a measure of Strehl ratio is used. Total mass of the primary mirror is given as a constraint to the optimization problem. The sensitivities of the objective function and constraint are calculated by direct differentiation method. Optimization procedure is carried out by an optimality criteria method. For the light-weight primary mirror design, a three dimensional model is treated. As a preliminary example, topology optimization considering a self-weight loading is treated. In the second example, the polishing pressure is also included as a loading in the topology optimization of the mirror. Results of the optimized design topology for the mirror with various mass constraints are presented.
The Development of KOGAS Membrane for LNG Storage Tank
Oh, Byoung-Taek ; Kim, Young-Kyun ; Yoon, Ihn-Soo ; Seo, Heung-Seok ; Hong, Seong-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1203~1208
DOI : 10.3795/KSME-A.2002.26.6.1203
LNG demand has been rapidly increasing in Korea for a variety of reasons including stable supply, non-polluting, and high combustion efficiency characteristics. As a result the construction and expansion of LNG storage facilities have been continuing at a vigorous pace. Korea Gas Corp. (KOGAS) has developed the design technology of the LNG storage tank. One of the most important structural core element of the LNG storage tank is the membrane, made by stainless steel. The membrane to be applied inside of LNG storage tank is provided with corrugations to absorb thermal contraction and expansion caused by LNG temperature. Analytical results have been performed to investigate the strength of the membrane and the reaction farce at the anchor point. Experimental studies are performed to investigate the deformation and strength of the membrane which is designed by Kogas. All experiments are conducted on the basis of RPIS, and we found the results are fully satisfied with the RPIS.
An Effect of Warm Shot Peening on the Fatigue Behavior of Suspension Coil Springs
Kim, Ki-Jeon ; Chung, Suk-Choo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 6, 2002, Pages 1209~1216
DOI : 10.3795/KSME-A.2002.26.6.1209
The requirements of coil spring fer higher fatigue strength have been increased to achieve the weight reduction of a vehicle. As the possible increase in fatigue strength by using the conventional shot peening treatment is found to be limited, it is necessary to modify the shot peening treatment. The warm shot peening is a shot peening treatment carried out within warm temperature range. The aim of this paper is to analyze some experimental results concerned with the effect of warm shot peening and to discuss the mechanism of warm shot peening in detail. By the results of rotating bending fatigue test, the fatigue strength of test specimen increases up to 23.8% in the production condition of warm shot peening at 200
compared with conventional shot peening. The major reason why the warm shot peening is effective to the improvement of fatigue strength is the increase of a compressive residual stress distribution, which can be caused by more effective deformation under the condition of warm temperature.