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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 22, Issue 4 - Apr 1998
Volume 22, Issue 3 - Mar 1998
Volume 22, Issue 2 - Feb 1998
Volume 22, Issue 1 - Jan 1998
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Electro-thermal analysis of contacts and connections in VCB under high electric current by finite element methods
Kang, Woo-Jong ; Huh, Hoon ; Kang, Kyeong-Rok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 715~722
DOI : 10.22634/KSME-A.19184.108.40.2065
A large electric system of a vacuum circuit breaker(VCB) has been studied for the electro-thermal analysis by finite element methods. Since the heat generation in VCB causes not only energy loss but deterioration of the VCB system with oxidization of parts, the overheating of the system must be prevented. For the analysis, a finite element formulation is derived for both electric analysis and thermal analysis that are coupled together. Two sets of formulations are uncoupled after finite dimensional approximation. First, the electric potential is obtained for the entire field and scaled to the given electric current. The electric field obtained is then used to calculate the heat generation in the VCB system including contacts and connections for the calculation of the temperature distribution in the entire domain. The finite element analysis is carried out to study the effect of shapes and locations of contacts and connections. From the results, the existing VCB has been modified to enhance its capacity with reduction of heat generation and temperature elevation.
Analysis of edge drop and development of numerical formula for edge drop control of cold rolled sheet
Song, Gil-Ho ; Park, Hae-Du ; Jin, Cheol-Je ; Sin, Seong-Gap ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 723~730
DOI : 10.22634/KSME-A.19220.127.116.113
With the introduction of edge drop control system in Tandem Cold Rolling Mill, it is necessary to develop te numerical expression for the set-up and edge drop automatic control of cold rolled sheet. As a first step we developed a simulation program which predicts profile and the amounts of edge drop at the delivery side of each stand by using roll deformation anlysis with the slit roll model. And by using the program the effect of various rolling conditions on edge drop was investigated. As a result the relations were obtained between the amounts of edge drop and rolling conditions. Based on above relations, the numerical expression was developed for the set-up and automatic control of edge drop by multi-regression of simulation results for the variation of edge drop amount with each rolling condition.
An analysis of bolted opening structure and development of analysis expert system using ANSYS
Jeon, Seong-Mun ; Seo, Ui-Gwon ; Sim, Hyeon-Bo ; Kim, Tae-Hwan ; Lee, Bu-Yun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 731~742
DOI : 10.22634/KSME-A.1918.104.22.1681
Bolted opening structures is widely applied for class 1 machinery of nuclear plant with strict design requirement. As the shape of the bolted opening structure is non-axisymmetric due to the existence of stud bolts although it is almost axi-symmetric, 3D analysis is required to satisfy such kind of design requirements. Because as much as possible trial computations are need to get an optimal design condition in the limited period of basic design, an easy and fast analysis tool is useful in the design stage. In the paper, a transformation technique of non-axisymmetric problem into quasi-axisymmetric has been proposed based on the general purpose commercial code ANSYS. Both the pre-processor which incorporates the technique and prepares data and post-processor which prepares arranged results from the huge output of commercial code have been developed to help the design engineers.
Finite element analysis of flow and heat transfer in solid particle moving beds of heat exchanger
Lee, Wan-Sul ; Youn, sung-kie ; Park, Sang-Il ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 743~752
DOI : 10.22634/KSME-A.1922.214.171.1243
Numerical analysis for the flow and heat transfer in solid particle moving beds of heat exchangers is presented. The solid particle flow through the bundle of heat source tubes by the gravitational force. The heat energy is transferred through the direct contact of particles with the heat source tubes. The viscous-plastic fluid model and the convective heat transfer model are employed in the analysis. The flow field dominantly influences the total heat transfer in a heat exchanger. As the velocities of solid particles around the heat source tubes increase, the amount of heat transfer from the tubes increases. Some examples are presented to show the performance of the numerical model. The flow effect on the heat transfer is also studied through the examples.
A study on sound radiation from isotropic plates stiffened by unsymmetrical beams
Kim, Taek-Hyeon ; O, Taek-Yeol ; Kim, Jong-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 753~761
DOI : 10.22634/KSME-A.19126.96.36.1993
The determination of sound pressure radiated from periodic plate structures is fundamental in the estimation of noise level in aircraft fuselages or ship hull structures. As a robust approach to this problem, here a very general and comprehensive analytical model is developed for predicting the sound radiated by a vibrating plate stiffened by periodically spaced orthogonal unsymmetrical beams subjected to a sinusoidally time varying point load. The plate is assumed to be infinite in extent, and the beams are considered to exert both line force and moment reactions on it. Using this theoretical model, the sound pressure levels on axis in a semi-infinited fluid (water) bounded by the plate were calculated using three numerical tools such as the Gauss-Jordan method, the LU decomposition method and the IMSL numberial package. Especially, the variation in the sound pressure levels and their modes were investigated according to the change in frequency, bay spacing and bay distance.
A study on the idle gear rattle vibration and noise reduction for heavy duty truck
Ahn, Byoung-Min ; Chang, Il-Do ; Hong, Dong-Pyo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 762~767
DOI : 10.22634/KSME-A.19188.8.131.522
The main torsional vibration source of the powertrain is the fluctuation of engine torque. The gear rattle is impact generating in the backlash of the free gear due to this torsional vibration. Optimization of the clutch torsional characteristic is one of the effective method to reduce the idle gear rattle. Many researches have been reported on this problem but only few of them give sufficient consideration to the detailed clutch modeling and the experiment. This paper pays attention to the optimization of clutch design parameters and the experiment to reduce the idle gear rattle vibration and noise.
Dynamic analysis and control of a robot leg with a shock absorber
Oh, Chang-Geun ; Kang, Sung-Chul ; Lee, Soo-Yong ; Kim, Mun-Sang ; Yoo, Hong-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 768~778
DOI : 10.22634/KSME-A.19184.108.40.2068
Human beings usually absorb a shock from terrain during walking through the damping effects of joints, muscles and skin. With this analogy, a robot-leg with a shock absorber is built to absorb the impact forces at its foot during high-speed walking on irregular terrain. To control the hip position while walking, the dynamic controller suitable for high speed walking is designed and implemented based on a dynamic model by Kane's equation. The hip position tracking performances of various controllers (PID controller, computed torque controller and feedforward torque controller) are compared through the experiments of the real robot-leg.
Collinear cracks in a layered structure with a thermoelastically graded interfacial zone under thermal shock
Choi, Hyung-Jip ; Jin, Tae-Eun ; Lee, Kang-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 779~789
DOI : 10.22634/KSME-A.19220.127.116.119
In this paper, the thermal shock responses of collinear cracks in a layered medium are investigated based on the uncoupled, quasi-static plane thermoelasticity. The medium is modeled as a bonded structure composed of a surface layer and a semi-infinite substrate. Between these two dissimilar homogeneous constituents, a functionally graded interfacial zone exists with the nonhomogeneous features of continuously varying thermoelastic properties. Three cracks are assumed to be present in the layered medium, one in each one of the constituent materials, aligned collinearly normal to the nominal interfaces. A system of singular integral equations is solved, subjected to the forcing terms of equivalent transient thermal tractions acting on the locations of cracks via superposition. Main results presented are the transient thermal stress intensity factors to illustrate the parametric effects of various geometric and amterial combinations of the medium with the thermoelastically graded interfacial zone and the collinear cracks.
Display of operating feel of virtual tool in frictional contact with elastically deforming environment
Choi, Hyoukryeol ; Lee, Seungryong ; Ryew, Sungmoo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 790~800
DOI : 10.22634/KSME-A.1918.104.22.1680
This paper presents a haptic rendering algorithm in the case that the virtual environment elastically deforms in response to the force applied by a user with a virtual tool. Considering friction, elasticity, multiple contacts and dynamics of the virtual object, this algorithm lets the operator have the feel of interactions in the virtual environment as close as to the reality. Based on the proposed algorithm several experiments are conducted and its effectiveness is confirmed.
Understanding of dynamic system properties in the frequency domain using bond graphs
Park, Jeon-Soo ; Kim, Jong-Shik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 801~810
DOI : 10.22634/KSME-A.1922.214.171.1241
Modeling and analysis of dynamic systems generally demand their resutls to be interpreted each other with a physical sense. It sometimes requires that there should exist a unified tool in the treatment of dynamic systems which can be applied to both their modeling and analysis equally. This paper shows how models just after the progress of modeling via bond graph standards are converted to ones which are appropriate for analyzing a dynamic system in the frequency domain. Four bond graph prototypes are introduced to obtain frequency properties of dynamic systems such as zero stability, relative order, zero and pole dynamics, etc. directly from bond graphs, and the method are proposed which reduces nearly all models of bond graph standards to one of the prototypes without any change of physical similarity. This procedure as a tool for the structural reduction of bond graphs and finding frequency properties of a dynamic system is further investigated to survey its effectiveness through an example.
Dynamic response optmization using approximate search
Kim, Min-Soo ; Choi, Dong-hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 811~825
DOI : 10.22634/KSME-A.19126.96.36.1991
An approximate line search is presented for dynamic response optimization with Augmented Lagrange Multiplier(ALM) method. This study empolys the approximate a augmented Lagrangian, which can improve the efficiency of the ALM method, while maintaining the global convergence of the ALM method. Although the approximate augmented Lagragian is composed of only the linearized cost and constraint functions, the quality of this approximation should be good since an approximate penalty term is found to have almost second-order accuracy near the optimum. Typical unconstrained optimization algorithms such as quasi-Newton and conjugate gradient methods are directly used to find exact search directions and a golden section method followed by a cubic polynomial approximation is empolyed for approximate line search since the approximate augmented Lagrangian is a nonlinear function of design variable vector. The numberical performance of the proposed approach is investigated by solving three typical dynamic response optimization problems and comparing the results with those in the literature. This comparison shows that the suggested approach is robust and efficient.
Impact energy absorbing effect by the buckling of impact limiter's case of radioactive material transport cask
Ku, Jeong-Hoe ; Seo, Gi-Seok ; Min, Deok-Gi ; Kim, Yeong-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 826~833
DOI : 10.22634/KSME-A.19188.8.131.526
The energy-absorbing characteristic of impact limiters affects the cask design so significantly that it should be evaluated as accurate as possible. The objective of this study is to find the influence of the impact limiter's steel case and gusset plates which enclose the shock absorbing cellular material on the impact energy absorption. The influence of impact limiter's steel case and gusset plate stiffeners on the impact energy absorption behavior under horizontal drop impact was evaluated for a radioactive isotope transport cask. Though the impact limiters mitigate the impact damage of the cask, the impact limiter's steel case and gusset plate stiffeners increase the impact force so significantly that should be designed as soft as possible. The impact analysis without considering impact limiter's steel case and gusset plates stiffener gives non-conservative results, so the stiffness of the steel case and gusset plates should be considered in impact analysis.
A study on the through crack behavior of aluminum alloy with cantilever beam type under variable load
Yoo, Heonil ; Kim, Yeob-Rae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 834~842
DOI : 10.22634/KSME-A.19184.108.40.2064
This paper examines the crack growth behavior of 7075-T651 and 5052-H32 aluminum alloy under high-low block loading condition. The cantilever beam type specimen with a chevron notch is used in this study. The crack growth and closure ae investigated by compliance method. The applied stress ratios are R=0.15, 0.0, -0.15 and R=-0.15, 0.0, 0.15. The crack growth rate was found to increase as the load amplitude increases. However,
was almost independent on the stress ratio. The experimental constants of 7075-T651 and 5052-H32 in Paris law were c`=1-1.3
of 7075-T651 and 5052-H32 becomes smaller as the stress ratio decreases. It seems that the crack closure affects
A lateral vibration damper using leaf springs
Je, Yang-Gyu ; Kim, Jong-Su ; Jeong, Si-Yeong ; Hong, Seong-Uk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 843~858
DOI : 10.22634/KSME-A.19220.127.116.113
This paper intoduces a new lateral damper, which is simply called "leaf spring damper(LSD)", using the leaf springs. The principle and the contruction of this novel damper is described in detail. The theoretical analysis of the damper is presented. The advantages of this novel damper are discussed. Experiments are performed on four dampers which have the different stiffness and damping coeficients respectively. The dynamic coefficients of the dampers and the temperature rise of working fluid are measured as the vibration speeds. The experimental results are compared with the theoretical results and it is found a good agreement.agreement.
A study on the static and stability characteristics of the oil-lubricated herringbone groove journal bearing
Kang, Kyung-Phil ; Rhim, Yoon-Chul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 859~867
DOI : 10.22634/KSME-A.1918.104.22.1689
An oil lubricated Herringbone aroove jounal bearing(HGJB) with eight-circular-profile grooves on the non-rotating bearing surface is analyzed numerically and experimentally. The load carrying capacity, attitude angle, stiffness and damping coefficients are obtained numerically for the various bearing configurations. The onset speed of instability is also examined for the various eccentricity ratios. The configuration parameters of HGJB, such as groove depth ratio, groove width ratio, and groove angle, are dependent on each other because the grooves are generated by using eight small balls rolling over the inner surface of the sleeve with press fit. Therefore, it is not allowed to suggest a set of optimal design parameters such as the one for the rectangular profile HGJB. The overall results from numerical and experimental analysis prove that the circular profile HGJB has an excellent stability characteristics and the higher load carrying capacity than the plain journal bearing.
Modeling and optimal design of monolithic precision XYZ-stage using flexure mechanism
Shim, Jong-Yeop ; Gweon, Dae-Gab ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 868~878
DOI : 10.22634/KSME-A.1922.214.171.1248
There are recently increasing needs for precision XYZ-stage in the fields of nanotechnology, specially in AFMs(Atomic Force Microscope) and STMs(Scanning Tunneling Microscope). Force measurements are made in the AFM by monitoring the deflection of a flexible element (usually a cantilever) in response to the interaction force between the probe tip and the sample and controlling the force neasyred constant topography can be obtained. The power of the STM is based on the strong distance dependence of the tunneling current in the vacuum chamber and the current is a feedback for the tip to trace the surface topography. Therefore, it is required for XYZ-stage to position samples with nanometer resolution, without any crosscouples and any parasitic motion and with fast response. Nanometer resolution is essential to investigate topography with reasonable shape. No crosscouples and parasitic motion is essential to investigate topography without any shape distortion. Fast response is essential to investigate topography without any undesirable interaction between the probe tip and sample surface ; sample scratch. To satisfy these requirements, this paper presents a novel XYZ-stage concept, it is actuated by PZT and has a monolithic flexible body that is made symmetric as possible to guide the motion of the moving body linearly. PZT actuators have a very fast response and infinite resolution. Due to the monolithic structure, this XYZ-stage has no crosscouples and by symmetry it has no parasitic motion. Analytical modeling of this XYZ-stage and its verification by FEM modeling are performed and optimal design that is to maximize 1st natural frequencies of the stage is also presented and with that design values stage is manufactured.
Radiation characteristics on a stiffened plate structure
Kang, Jun-soo ; Kim, Jeung-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 879~886
DOI : 10.22634/KSME-A.19126.96.36.1999
It is very important to understand the vibration and noise characteristics of a structure to developed quiet machines and lessen their noise. In this paper, the vibration and sound radiation characteristics of a simple and a bar-stiffened plate have been investigated using numerical and experimental techniques. In numerical process, FEM analysis has been performed for the vibration level ; the time-space squared and averaged velocity and BEM analysis for sound radiation parameters ; sound power and radiation efficiency. In experimental process, FFT signal processing method has been used. While a power from an exiciter is applied to the structure by using a point contact, sound intensity and vibration level has been measured. Based on these two data, the radiation efficiency has been calculated. Results show that the radiation efficiency for the stiffened structure increases compared to the simple plate, due to the extra edges provided by the stiffener.
사각튜브의 국부좌굴과 전체좌굴에 관한 연구 I
Han, Byeong-Gi ; Park, Bong-Hyeon ; An, Dae-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 887~894
DOI : 10.22634/KSME-A.19188.8.131.527
This paper presents the results of analytical invesstigation of the buckling behavior of thin-walled box-section column. Throughout this investigation, the single curve for finding the buckling stress at each effective slenderness ratio is derived by modification of the Rankine's formula. The applicable formula in the small slederness region is derived by considering the inelastic behavior of material. Additionally, the bifurcation criterion(slenderness ratio) which can distinguish between the local and overall buckling mode shapes is suggested by equating the local and overall buckling stresses. The overall buckling formula is closely concurrent with the experiments for the rectangular tubes.
The Relationship Between Local and Overall Buckling of Rectangular Tubes (II)
Han, Byeong-Gi ; Park, Bog-Hyeon ; An, Dae-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 895~904
DOI : 10.22634/KSME-A.19184.108.40.2065
This paper presents the results of experimental investigation of the buckling behavior of thin-walled box-section column. The experiments for finding the buckling stress and bifurcation slenderness ratio are performed by the method from AISC. The sets of boundary conditions are both end simply supported, one end simply supported and the other end clamped, and both ends clamped. The types of specimens are clssified by thickness to width ratio. The experiments for the thin-walled rectangular tubes are closely concurrent with the theoretical values of overall buckling load and bifurcation slenderness ratio that are suggested by the part (I) of this paper.
자동차용 구조접착접합이음의 응력해석과 강도평가에 관한 연구
Yu, Yeong-Cheol ; O, Seung-Gyu ; Lee, Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 905~915
DOI : 10.22634/KSME-A.19220.127.116.115
Static tensile tests using adhesive-bonded single-lap joints of aluminum alloy were conducted to investigate the effect of geometric factor, overlap length, adherend thickness, adhesive thickness and material composition of adherend/adhesive on the strength of adhesive joint. The average applied shear stress at joint fracture decreased with increasing lap length. However increasing the adherend thickness resulted in a higher joint strength. Higher yield strength of adherend and lower elastic modulus of adhesive is advantageous to the adhesive joint. Newly proposed modified joint factor could be well evaluated the influence of lap length, adherend thickness and adhesive thickness on the bond strength for adhesive joints.
Infinite determinant method for stability analysis of parametrically excited systems
Hyun, Sang-Hak ; Yoo, Hong-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 916~923
DOI : 10.22634/KSME-A.1918.104.22.1686
In this paper, an infinite determinant method is presenstd for stability analysis of parametrically excited systems. Unstable regions of the combination parametric resonance as well as principal resonance can be identified with the method. A numerical problem of relatively large amplitude of excitation is solved, and the results of the presented method are compared to those of the multiple scales perturbation method. It is found that the presented method obtains more accurate transition curves which divide stable and unstables in the parameter plane than those of the multiple scales perturbation method.
Densification behavior of ceramic powder under cold compaction
Choi, Seung-Wan ; Kim, Gi-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 924~938
DOI : 10.22634/KSME-A.1922.214.171.1244
Densification behavior of ceramic powder under cold compaction was investigated. Experimental data were obtained for zirconia powder and alumina powder under triaxial compression with various loading conditions. A special form of the Cap model was proposed from experimental data under triaxial compression for a yield function of ceramic powder. The proposed yield function was inplemented into a finite element program (ABAQUS) to study densification behaviors of zirconia and alumina powders under die compaction. The effect of friction between the powder and die wall was also investigated. Density distributions of powder compacts were measured and compared with finite element results.
A study on the design of vibration damper for high speed CD-ROM drives
Chang, Seung-Hwan ; Kim, Hyeon-Seok ; Choi, Jin-Gyeong ; Lee, Dae-Gil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 939~952
DOI : 10.22634/KSME-A.19126.96.36.1999
Rubber dampers are widely used to damp out vibrations generated in many mechanical elements because of the excellent damping characteristics of rubber. The damping characteristics of rubber is much dependent on temperature and frequency, which, in some cases, limit the effectiveness of rubber dampers. In this study, in order to increase the damping properties and axial and cross stiffnesses of rubber vibration dampers which are used in recording and regenerating devices, solid cores were inserted with interference tolerance in the rubber dampers. The damping characteristics of the rubber dampers with cores were investigated by experimentally and numerically using finite element method with respect to the interference tolerance, the core roughness, the materials of the core and the environmental temperature. From the experimental and theoretical investigations, it was found that the core in the rubber increased both the damping and stiffness of the damper. Also, it was found that the damping and stiffness of the rubber damper were much dependent on the temperature and frequency. Using the results of the experimental and theoretical investigations, the optimum design method for the cored rubber damper for recording and regenerating devices was developed.
Effects of Aspect and Area Ratio of Fiber on the Accuracy of Intensity Method in Measurement of Fiber Orientation-Angle Distribution
Lee, Sang-Dong ; Kim, Hyeok ; Lee, Dong-Gi ; Han, Jil-Yeong ; Kim, Lee-Gon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 4, 1998, Pages 953~959
DOI : 10.22634/KSME-A.19188.8.131.523
To investigate accuracy of intensity method for measurement of the fiber orientation distribution, fiber orientation function is calculated by drawing simulation figures for the fiber orientation as varying fiber aspect ratio, fiber area ratio, and fiber orientation state, respectively. The values of fiber orientation function measured by intensity method are compared with the calculated values of fiber orientation function. The results show that measurement accuracy of the fiber orientation angle distribution by intensity method is affected by the fiber aspect ratio when the total length of oriented fiber is same. The average gradient of fiber orientation function is 0.94 for 1000mm of the total fiber length and is 0.93 for 2000 mm when the fiber aspect ratio is over 50. Measurement accuracy by intensity method is about 94% and the reliable data can be obtained by intensity method.