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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
Journal Basic Information
Journal DOI :
The Korean Society of Mechanical Engineers
Editor in Chief :
Volume & Issues
Volume 21, Issue 12 - Dec 1997
Volume 21, Issue 11 - Nov 1997
Volume 21, Issue 10 - Oct 1997
Volume 21, Issue 9 - Sep 1997
Volume 21, Issue 8 - Aug 1997
Volume 21, Issue 7 - Jul 1997
Volume 21, Issue 6 - Jun 1997
Volume 21, Issue 4 - Apr 1997
Volume 21, Issue 5 - Jan 1997
Volume 21, Issue 3 - Jan 1997
Volume 21, Issue 2 - Jan 1997
Volume 21, Issue 1 - Jan 1997
Selecting the target year
Design of a lighting system for PCB visual pattern inspection
Na, Hyun-Chan ; Rho, Byung-Ok ; Ryu, Yung-Kee ; Cho, Hyung-Suck ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 1~11
DOI : 10.22634/KSME-A.19126.96.36.199
Austomated visual inspection(AVI) capability has become an important key component in the automated manufacturing system. In such a visual inspection system an intensity(or color) image of a scene is quickly affected by optical property of objects, condition and roughness of surface, lens and filters, image sensor property and lighting system. In particular, the lighting system disign is the most important factor, since it affects overall performance of the visual system. For fast and cheap automated visual inspection system it is important to obtain the good image quality which results from careful attention to the design of the lighting system. In this paper, the lighting subsystem of AVI system is analysed for the inspection of printed circuit board(PCB) patterns. The spectral reflectance of materials, which are composed of PCB, is measured for choosing the light source. The reflection property is theoretically obtained by a reflection model and also obtained by experiments which measure intensity with varying the viewing direction of image sensor and the lighting direction of illuminator. The illumination uniformity of a ring-type illuminator. The lighting system is designed based upon the experimental results and theoretial analysis.
Semi Empirical Analysis on the Crushing Mechanism of Thin-Walled Rectangular Tubes
Kim, Cheon-Uk ; Han, Byeong-Gi ; Im, Chae-Hong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 12~21
DOI : 10.22634/KSME-A.19188.8.131.52
A model for analysis of the crushing mechanism of thin-walled rectangular tube is presented. The crushing modes of rectangular tubes may be characterized as either compact or noncompact and the model presented only considers compact modes. The unloading process in the crushing are categorized into three different stages where the distinction is based on the ratio of outward to inward fold length. Using the kinematic relations and the energy conservation principle, the instantaneous crush load is derived. An approximate equation that considers the rolling behavior is also given so that the crush load history may be established. The equation is experimentally proved.
Assessment of Residual Life for In-Service Fossil Power Plant Components Using Grain Boundary Etching Method
Han, Sang-In ; Yoon, Kee-Bong ; Chung, Se-Hi ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 22~31
DOI : 10.22634/KSME-A.19184.108.40.206
The grain boundary etching method as a method for assessing degradation of structural materials has received much attention because it is simple, inexpensive and easy to apply to real components. In this study, the effectiveness of the method is verified by successfully applying the technique to in-service components of aged fossil power plants such as main steam pipes, boiler headers an turbine rotors. A new degradation parameter, intersecting number ratio (N
), is employed. The intersecting number ratio (N
) is defined as the ratio of intersection number (N
) obtained from 5-minute picric acid etched surface to the number (N
) obtained from nital etched surface. Two kinds of test materials, 2.25Cr-1Mo steel and 1Cr-1Mo-0.25V steel, were artificially thermal-aged at 630.deg. C in different levels of degradation., (N
) were measured. And, correlations between the measured values and LMP values calculated from aging temperature and aging time were sought. To check the validity of the correlations obtained in laboratory, similar data were measured from service components in four old Korean fossil power plants. These on-site measurement data were in good correlation with those obtained in the laboratory.oratory.
Design of High-Order Moving Sliding Surface via Fuzzy Algorithm
Park, Dong-Won ; Choi, Seung-Bok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 32~44
DOI : 10.22634/KSME-A.19220.127.116.11
A moving sliding surface(MSS) was proposed earlier for the second-order variable structure control system(VSCS). The MSS was disigned to pass arbitrary initial conditions, and subsequently moved towards a predetermined sliding surface by rotating and/or shifting. This methodology led to fast and robust control responses of the second-order VSCS, especially in a reaching phase. However, the moving algorithm of the MSS was too complicated to be employed to the high-order VSCS. To resolve this problem, a new moving algorithm based on the fuzzy theory is proposed in this paper. For the generalization of the MSS, the conditions for rotating or shifting are firstly investigated. Then the fuzzy algorithm is formulated by adopting the values of the surface function and the total discontinuity gain as input variables, and the variation of the surface function as output variable. The position control problem of an electrohydraulic servomechanism is adopted in order to demonstrate the efficiency and the feasibility of the proposed MSS associated with fuzzy algorithm.
Design of Fly-Cutter for Antisymmetric Screw Rotor
Choi, Sang-Hun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 45~52
DOI : 10.22634/KSME-A.1918.104.22.168
In this study, we designed tooth profile of the fly-cutter for antisymmetric rotor which is used in screw compressor. In order to verify this profile, we manufactured three different pairs(J46, N46, P46) of antisymmetric rotor using fly-cutter. We got the following conclusions from this study. (1) We obtained better contact condition using 3pairs of rotor which are manufactured by the fly-cutter. (2) We could prevent the cutter interference near bottom point of the robe of screw rotor.
A Study On the Friction Torque and Temperature Distribution of Magnetic Fluid Seals
Kim, Chung-Kyun ; Kim, Han-Goo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 53~61
DOI : 10.22634/KSME-A.1922.214.171.124
The performance characteristics of magnetic fluid seals are studied numerically as a function of working gap, pole width, angle of pole sharpening, and shaft speed. The temperature distribution of a magnetic fluid seal with multiple tooth is investigated as a function of the contact fraction of magnetic fluids at the periphery of pole tooth using a finite element method. The most significant design parameter of a magnetic fluid seal is the working gap between the pole pieces and the rotating shaft. The result shows that with increasing the working gap, the friction torque decreases radically. The practical working gap for the pole pieces with triangular tooth zone profile is 0.2-0.4mm. The FEM results indicate that the optimal filling of a magnetic fluid between the pole pieces and the shaft is very important due to the accumulations of nonuniform friction heating within the pole pieces, which may interfere the magnetic circuit flow.
A Visual Calibration Scheme for Off-Line Programming of SCARA Robots
Park, Chang-Kyoo ; Son, Kwon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 62~72
DOI : 10.22634/KSME-A.19126.96.36.199
High flexibility and productivity using industrial robots are being achieved in manufacturing lines with off-line robot programmings. A good off-line programming system should have functions of robot modelling, trajectory planning, graphical teach-in, kinematic and dynamic simulations. Simulated results, however, can hardly be applied to on-line tasks until any calibration procedure is accompained. This paper proposes a visual calibration scheme in order to provide a calibration tool for our own off-line programming system of SCARA robots. The suggested scheme is based on the position-based visual servoings, and the perspective projection. The scheme requires only one camera as it uses saved kinematic data for three-dimensional visual calibration. Predicted images are generated and then compared with camera images for updating positions and orientations of objects. The scheme is simple and effective enough to be used in real time robot programming.
Near-net-shape forming of ceramic powder under hot pressing and hot isostatic pressing
Kwon, Yeong-Sam ; Kim, Ki-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 73~82
DOI : 10.22634/KSME-A.19188.8.131.52
High temperature densification behaviors of alumina powder compacts were investigated under hot pressing and hot isostatic pressing. An alumina part of valve-head shape was fabricated under hot pressing and its forming process was simulated by finite element calculation. an alumina powder compact encapsulated by a stainless steel container was also densified under hot isostatic pressing. Inhomogeneous deformations during hot isostatic pressing due to the canning effect were observed experimentally and predicted by finite element analysis.
A Study on the Development of Cu-based Sintered Friction Materials
Lee, Jong-Hyung ; Choi, Byung-Ho ; kim, Jeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 83~92
DOI : 10.22634/KSME-A.19184.108.40.206
In a study on the development of Cu-based sintered friction materials, the specimens pressed with various compacting pressures
have been evaluated to find the optimum condition of compacting pressure. As compacting pressure increased up to
, mechanical properties such as density, hardness, bending strength, wear and coefficient of friction, etc. improved remarkably, but up to 6 ton/cm
, decreased slightly because of traps of gases and water vapors in specimen. Disk assembly composed of 12 pieces of Cu-based friction materials has been compared with one of asbestos-and nonasbestos-based friction materials. In dynamic and driving tests to find burst spin strength, corrosion area rate and friction properties, etc., Cu-based sintered friction materials showed better properties than the others, especially in severe conditions because oxides such as
in the friction surface of friction materials were formed.
The Effect of Specimen Size in Charpy Impact Testing
Kim, Hun ; Kim, Ju-Hak ; Ji, Se-Hwan ; Hong, Jun-Hwa ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 93~103
DOI : 10.22634/KSME-A.19220.127.116.11
Charpy V-notch impact tests were performed on the full-, half-and third-size specimens from two ferritic SA 508 Cl. 3 steels for nuclear pressure vessel. New normalization factors were proposed to predict the upper shelf energy(USE) and the ductile-brittle transition temperature(DBTT) of full-size specimens from the measured data on sub-size specimens. The factors for the USE and the DBTT are
respectively, where B the width, b the ligament size,
the elastic stress concentration factor, and R the notch root radius. These correlations successfully estimated the USE and DBTT of the full-size specimens based on sub-size specimen data. In addition, the size effects were studied to develop the correlations among absorbed energy, lateral expansion(LE) and displacement. It was also found that the LE was able to be estimated from the displacement obtained by the instrumented impact test, and that the displacement would be used as a criterion for the toughness of the steels corresponding to change in their yield strength.h.
Additional Damage of A17075-T651 under
Out-of phase Biaxial Loading from Crystal Structure Dependence
Lee, Hyun-Woo ; Oh, Se-Jong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 104~111
DOI : 10.22634/KSME-A.1918.104.22.168
Accounting for the additional damages come out from non-proportional loading path effect, material damage according to crystal structure dependence was studied. Microscopic observations of damaged material by SEM(Scanning Electron Microscope) showed crystal structure dependence. Biaxial in-phase loaded specimens showed the slips of same direction, which pararell each other, but biaxial 90.deg. out-of-phase loaded specimens showed multiply crossed slips. S. H. Doong and D. F. Socie reported that wavy/planar or planar slip material showed the increase in the cyclic hardening level during non-proportional cycling. From these results, the additional hardening and non-proportional loading effects were related with slip mechanism, and the slip mechanism was related with crystal structure. In the present study, a damage mechanism which accounts for the non-proportional loading effect from crystal structure dependence was considered and applied to A17075-T651.
Robust Structural Optimization Considering the Tolerances of Design Variables
Lee, Gwon-Hui ; Park, Gyeong-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 112~123
DOI : 10.22634/KSME-A.1922.214.171.124
The optimization techniques have been applied to versatile engineering problems for reducing manufacturing cost and for automatic design. The deterministic approaches or op5imization neglect the effects on uncertainties of design variables. The uncertainties include variation or perturbation such as tolerance band. The optimum may be useless when the constraints considering worst cases of design variables can not be satisfied, which results from constraint variation. The variation of design variables can also give rise to drastic change of performances. The two issues are related to constraint feasibility and insensitive performance. Robust design suggested in the present study is developed to gain an optimum insensitive to variation on design variables within feasible region. The multiobjective function is composed to the mean and the standard deviation of original objective function, while the constraints are supplemented by adding penalty term to original constraints. This method has a advantage that the second derivatives of the constraints are not required. A mathematical problem and several standard problems for structural optimization are solved to check out the usefulness of the suggested method.
Evaluationof Growing Crack-Tip Singularity in A533B Steel by Image Processing Technique
Pyo, Chang-Ryul ; Kim, Yeong-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 124~132
DOI : 10.22634/KSME-A.19126.96.36.199
This paper describes an experimental and numerical study on growing ductile crack-tip behaviors. The hybrid experimental and numerical method by means of a computer image processign technique, was applied to the analysis of both base metal and weld metal CT specimens. In the weld metal specimen, the initial crack-tip was placed in front of fusion line, and the crack orientation was perpendicular to it. Finite element analysis of crack growth behaviors in both base and weld matal specimens made of A533B Class 1 steel were also performed to examine the effects of weldment on near crack-tip fields. a series of experimental studies on crack-tip behaviors have clearly shown the qualitative effects of material properties, especially a hardening exponent. The experimental and numerical results have also shown that weldment does not affect displacement and strain fields near a crack-tip while a stress field is influenced by the difference between yield stresses of both base and weld metals.
Transient Piezothermoelasticity of a Piezo Ceramic Plate Subjected to Antisymmetric Thermal Load and Symmetric Thermal Load
Kim, Gyeong-Seok ; Choe, Jeong-Seok ; Yang, Seung-Pil ; Kim, Yong-Uk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 133~143
DOI : 10.22634/KSME-A.19188.8.131.52
Piezoelastic materials have recently attracted considerable attention because of their potential use in intelligent structural systems. In this paper, we treat a transient piezothermoelastic problem in a hexagonal plate of crystal class 6mm subjected to antisymmetric heating temperature. We analyze this problem by use of the potential function method. Numerical calculations are carried out for a cadmium selenide solid, and the results are presented graphically in comparison with those derived from the similar problem in a cadmium selenide plate subjected to symmetric heating temperature for a symmetry transient problem.
Real-time direct kinematics of a double parallel robot arm
Lee, Min-Ki ; Park, Kun-Woo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 144~153
DOI : 10.22634/KSME-A.19184.108.40.206
The determination of the direct kinematics of the parallel mechanism is a difficult problem but has to be solved for any practical use. This paper presents the efficient formulation of the direct kinematics for double parallel robot arm. The robot arm consists of two parallel mechanism, which generate positional and orientational motions, respectively. These motions are decoupled by a passive central axis which is composed of four revolute joints and one prismatic joint. For a set of given lengths of linear actuators, the direct kinematics will find the joint displacements of th central axis from geometric constraints in each parallel mechanism. Then the joint displacements will be converted into the position and the orientation of the end effector of the robot arm. The proposed formulation is decoupled and compacted so that it will be implemented as a real-time direct kinematics. With the proposed formulation, we analyze the motion of the double parallel robot and show its characteristics. Specially, we investigate the workspace in terms of positional space as well as orientational space.
Finite Element Analysis of Thermally-Induced Deformation in SMC Compression Molding
Lee, Jae-Hyoung ; Lee, Eung-Shik ; Youn, Sung-Kie ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 154~163
DOI : 10.22634/KSME-A.19220.127.116.11
Thermally-induced deformation in SMC(Sheet Molding Compound) products is analyzed using three dimensional finite element method. Planar fiber orientation, which causes the anisotropic material properties, is calculated through the flow analysis during the compression stage of the mold. Also curing process is analyzed to predict temperature profile which has significant effects on warpage of SMC products. Through the developed procedure, effects of various process conditions such as charge location, mold temperature, fiber contents, and fiber orientations on deformation of final products are studied. and processing strategies are proposed to reduce the warpage and the shrinkage.
for unidirectional laminated composites by using the two parameter technique
Rhee, Gyeong-Yeop ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 164~172
DOI : 10.22634/KSME-A.1918.104.22.168
Two parameter technique that uses far-field stress and displacement distributions was applied to composite laminates in order to calculate mode II energy release rate,
calculated by two parameter technique was compared with that calculated from the crack closure method to inspect the effectiveness of two parameter technique. Sensitivity study of two parameter technique to the crack extension size was also performed. The results showed that both methods produced comparable
results. In particular, it was found that although the crack closure method was affected by the crack extension size, the two parameter technique was less affected by the crack extension size.
A Study on the Fatigue Behaviors of Cr-Mo-V Alloy for Steam Turbine at High Temperature Difference
Song, Sam-Hong ; Kang, Myung-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 173~179
DOI : 10.22634/KSME-A.1922.214.171.124
The high temperature fatigue tests were performed using the specimens taken from Cr-Mo-V steel, widely used as thermal power plant turbine materials for examination fatigue behavior of materials in power plants which have been operated for long periods. The fatigue tests at high temperature were performed at the various temperature and applied stress. The results obtained are summarized as follows : The fatigue crack length increases and the fatigue life decreases with temperature and applied stress according to the same number of stress cycle. The fatigue crack propagation and the fatigue life were much influenced by temperature and applied stress.
Estimation of the Elastic Stiffness of TW-HDS Assembly
Song, Kee-Nam ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 1, 1997, Pages 180~187
DOI : 10.22634/KSME-A.19126.96.36.199
A formula for estimating the elastic stiffness of TW-HDS with a uniformly tapered width from w
over the length, has been analytically derived based on Euler beam theory and Castigliano's theorem. Elastic stiffnesses of the TW-HDSs designed in the same dimensional design spaces as the KOFA HDSs have been estimated from the derived formula, in addition, a sensitivity study on the elastic stiffness of the TW-HDSs has been carried out. Analysis results show that elastic stiffnesses of the TW-HDSs have been by far higher than those of the KOFA HDSs, and that, as the effects of axial and shear force on the elastic stiffness have been 0.15-0.21%, most of the elastic stiffness is attributed to the bending moment. As a result of sensitivity analysis, the elastic stiffness sensitivity at each design variable is quantified and design variables having remarkable sensitivity are identified. Among the design variables, leaf thickness is identified as that of having the most remarkable sensitivity of the elastic stiffness.