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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 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
Densification behavior and grain growth of zirconia powder compacts at high temperature
Kim, H.G ; Kim, K.T ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1175~1187
DOI : 10.22634/KSME-A.19188.8.131.525
Densification behavior and grain growth of zirconia powder compacts are investigated under high temperature. Experimental data are obtained for zirconia powder under pressureless sintering, sinter forging and hot isostatic pressing. The constitutive equations by Kwon et al. are used for diffusional creep and grain growth. The constitutive equations by McMeeking and co-workers are also included to study the effect of power-law creep. These constitutive equations are implemented into a finite element program (ABAQUS) to investigate the friction effect during sinter forging and the canning effect during hot isostatic pressing. The agreements between experimental data and finite element results are very good in pressureless sintering and hot isostatic pressing, but not as good in sinter forging.
Control of Nonlinear Systems with Mismatched Uncertainties Using an Output Feedback
Park, Chang Yong ; Seong, Yeol Wan ; Gwon, O Gyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1184~1184
DOI : 10.22634/KSME-A.19184.108.40.2064
In this paper, we design output feedback nonlinear dynamic control law by using state feedback nonlinear dynamic compensator and PI observer and show that the controller can stabilized globally and asymptotically a class of nonlinear systems with mismatched uncertainties. We also show that it is possible for a nonlinear system to use the output of PI observer in place of state variables in case that the nonlinear dynamic control law is used, similarly as in the linear system. The effectiveness of the proposed control law is demonstrated by a numerical simulation.
Control of nonlinear systems with mismatched uncertainties using an output feedback
Park, Chang-Yong ; Sung, Yul-Wan ; Kwon, Oh-Kyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1188~1194
DOI : 10.22634/KSME-A.19220.127.116.118
In this paper, we design output feedback nonlinear dynamic control law by using state feedback nonlinear dynamic compensator and PI observer and show that the controller can stabilize globally and asymptotically a class of nonlinear systems with mismatched uncertainties. We also show that it is possible for a nonlinear system to use the output of PI observer in place of state variables in case that the nonlinear dynamic control law is used, similarly as in the linear system. The effectiveness of the proposed control law is demonstrated by a numerical simulation.
Development of finite element analysis program and simplified formulas of bellows and shape optimization
Koh, Byung-Kab ; Park, Gyung-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1195~1208
DOI : 10.22634/KSME-A.1918.104.22.1685
Bellows is a component in piping systems which absorbs mechanical deformation with flexibility. Its geometry is an axial symmetric shell which consists of two toroidal shells and one annular plate or conical shell. In order to analyze bellows, this study presents the finite element analysis using a conical frustum shell element. A finite element analysis is developed to analyze various bellows. The validity of the developed program is verified by the experimental results for axial and lateral stiffness. The formula for calculating the natural frequency of bellows is made by the simple beam theory. The formula for fatigue life is also derived by experiments. The shape optimal design problem is formulated using multiple objective optimization. The multiple objective functions are transformed to a scalar function by weighting factors. The stiffness, strength and specified stiffness are considered as the multiple objective function. The formulation has inequality constraints imposed on the fatigue limit, the natural frequencies, and the manufacturing conditions. Geometric parameters of bellows are the design variables. The recursive quadratic programming algorithm is selected to solve the problem. The results are compared to existing bellows, and the characteristics of bellows is investigated through optimal design process. The optimized shape of bellows is expected to give quite a good guideline to practical design.
A study on the control of two-cooperating robot manipulators for fixtureless assembly
Choi, Hyeung-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1209~1217
DOI : 10.22634/KSME-A.1922.214.171.1249
This paper proposes the modeling of the dynamics of two cooperating robot manipulators performing the assembly job such as peg-in-hole while coordinating the payload along the desired path. The mass and moment of inertia of the manipulators and the payload are assumed to be unknown. To control the uncertain system, a robust control algorithm based on the computed torque control is proposed. Usually, the robust controller requires high input torques such that it may face input saturation in actual application. In this reason, the robust control algorithm includes fuzzy logic such that the magnitude of the input torque of the manipulators is controlled not to go over the hardware saturation while keeping path tracking errors bounded. A numerical example using dual three degree-of-freedom manipulators is shown.
A development of move limit strategy based on the accuracy of approximation for structural optimization
Park, Young-Sun ; Park, Gyung-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1218~1228
DOI : 10.22634/KSME-A.19126.96.36.1998
The move limit strategy is used to avoid the excessive approximation in the structural optimization. The size of move limit has been obtained by engineering experience. Recently, efforts based on analytic methods are performed by some researchers. These methods still have problems, such as prematurity or oscillation of the move limit size. The existing methods usually control the bound of design variables based on the magnitude. Thus, they can not properly handle the configuration variables based on the geometry in the configuration optimization. In this research, the size of move limit is calculated based on the accuracy of approximation. The method is coded and applied to the two-point reciprocal quadratic approximation method. The efficiency is evaluated through examples.
Pressure control of hydraulic servo system using proportional control valve
Yang, Kyong-Uk ; Oh, In-Ho ; Lee, Ill-Yeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1229~1240
DOI : 10.22634/KSME-A.19188.8.131.529
The purpose of this study is to build up control scheme that promptly control pressure in a hydraulic cylinder having comparatively small control volume, using a PCV (proportional control valve) and a digital computer. Object pressure control system has the character to be unstable easily, because the displacement-flow gain of the PCV is too large considering the small volume of the hydraulic cylinder and the time delay of response of the PCV is comparatively long. Considering the above-mentioned characteristics of the object pressure control system, in this study, control system is designed with two degree of freedom control scheme that is composed by adding a feed-forward control path to I-PDD
control system, and a reference model is used on the decision of control parameters. And through some experiments on the control system with FF-I-PDD
controller, the validity of this control method has been confirmed.
A study on the topology optimization of structures
Park, Sang-Hun ; Yun, Seong-Gi ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1241~1249
DOI : 10.22634/KSME-A.19184.108.40.2061
The problem of structural topology optimization can be relaxed and converted into the optimal density distribution problem. The optimal density distribution must be post-processed to get the real shape of the structure. The extracted shape can then be used for the next process, which is usually shape optmization based on the boundary movement method. In the practical point of view, it is very important to get the optimal density distribution from which the corresponding shape can easily be extracted. Among many other factors, the presence of checker-board patterns is a powerful barrier for the shape extraction job. The nature of checker-board patterns seems to be a numerical locking. In this paper, an efficient algorithm is presented to suppress the checker-board patterns. At each iteration, density is re-distributed after it is updated according to the optimization rule. The algorithm also results in the optimal density distribution whose corresponding shape has smooth boundary. Some examples are presented to show the performance of the density re-distribution algorithm. Checker-board patterns are successfully suppressed and the resulting shapes are considered very satisfactory.
Design and performance test of a foot for a jointed leg type quadrupedal walking robot
Hong, Ye-Seon ; Yi, Su-Yeong ; Ryu, Si-Bok ; Lee, Jong-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1250~1258
DOI : 10.22634/KSME-A.19220.127.116.110
This paper reports on the development of a new foot for a quadrupedal jointed-leg type walking robot. The foot has 2 toes, one at the front and the other at the rear side, for stable landing on uneven ground by point contact. The toes can move up and down independantly, guided by double-wishbone shaped parallel links which enable the lower leg to rotate with respect to a remote center on the ground surface. The motion of each toe is damped by a hydropneumatic shock absorber integrated in the foot in order to absorb the dynamic landing shock. Furthermore, the new foot can reduce the maximum hip joint drive torque by shortening the moment arm length between the hip joint and the landing force vector on the ground. Intensive experiments were carried out in this study by using a one-leg walking model to investigate the soft landing performance of the foot which could be hardly offered by conventional robot feet such as a flat plate with a gimbal type ankle joint. And it was confirmed that the hip joint torque of the leg walking on the flat surface could be reduced remarkably by using the new foot.
Residual life evaluation of pressurizer surge line nozzle in nuclear plant
Lee, Kang-Yong ; Kim, Jong-Sung ; Bae, Jung-Il ; Jin, Tae-Eun ; Youm, Hak-Ki ; Hong, Seong-Yul ; Jeong, Il-Suk ; Kim, Yoo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1259~1269
DOI : 10.22634/KSME-A.1918.104.22.1689
The procedure for the determination of the residual life of the pressurizer surge line nozzle in the nuclear plant is developed. The design fatigue life for the 1800
pressurizer surge line nozzle in cast head design is compared with that of Westinghouse stress report, and the percentage difference between two results is less than 9%. The design fatigue life evaluation of the 1000
pressurizer surge line nozzle in fabricated head design is carried out, and the consuming rate and residual life are estimated using the operating data.
Finite element analysis of reactor internals with structural faults
Jung, Seung-Ho ; Park, Jin-Seok ; Kim, Tae-Ryong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1270~1275
DOI : 10.22634/KSME-A.1922.214.171.1240
This paper concerns with the finite element analysis of reactor internals with structural faults. For investigating the influence of hold-down spring faults on dynamic characteristics of CSB (core support barrel), reactor internals of Ulchin-1 nuclear power plant are modeled using finite element method and simulated with artificial defects on the hold-down springs. To prove the validity of the finite element models, the calculated natural frequencies of CSB in normal state are compared with those from the measurement results, which shows good agreement. According to results of finite element analysis, CSB beam mode natural frequency decreases by 4.5% in the case of 10% partial relaxation of hold-down springs, and decreases by 18.4% in the case of 20%. The range of shell mode natural frequency change is within 5.3%.
Evaluation of an elastic stiffness sensitivity of leaf type HDS
Song, Kee-Nam ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1276~1290
DOI : 10.22634/KSME-A.19126.96.36.1996
The previous elastic stiffness formulas of leaf type holddown spring assemblies(HDSs) have been corrected and extended to be able to consider the point of taper runout for the TT-HDS and all the strain energies for both the TT-HDS and the TW-HDS based on Euler beam theory and Castigliano'stheorem. The elastic stiffness sensitivity of the leaf type holddown spring assemblies was analyzed using the derived elastic stiffness formulas and their gradient vectors obtained from the mid-point formula. As a result of the 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. In addition, it was found that the sensitivity of the leaf type HDS's elastic stiffness is exponentially correlated to the leaf thickness.
Analysis of elastic-plastic large deformation for polycrystalline solids
Kim, Young-Suk ; Kim, Jung-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1291~1297
DOI : 10.22634/KSME-A.19188.8.131.521
Elastic-plastic finite element(FE) simulation was performed for polycrystalline solids subjected to plane strain tensile loading. Using Asaro's double slip crystal plasticity model, the polycrystalline solids were modeled by assigning different initial slip directions to each grain. From the FE calculations, the microscopic deformation characteristics of polycrystalline solids were analyzed. Moreover, the effect of grain size and grain boundaries on the deformation characteristics were clarified.
A study on the analysis of grinding mechanism by using optimum in-process electrolytic dressing
Lee, Eun-Sang ; Kim, Jeong-Du ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1298~1310
DOI : 10.22634/KSME-A.19184.108.40.2068
In recent years, grinding techniques for precision machining of brittle materials used in electric, optical and magnetic parts have been improved by using superabrasive wheel and precision grinding machine. The completion of optimum dressing of superabrasive wheel makes possible the effective precision grinding of brittle materials. However, the present dressing system cannot have control of optimum dressing of the superabrasive wheel. In this study, a new system and the grinding mechanism of optimum in-process electrolytic dressing were proposed. This system can carry out optimum in-process dressing of superabrasive wheel, and give very effective control according to unstable current and gap increase. Therefore, the optimum in-process electrolytic dressing is a good method to obtain the efficiency and mirror-like grinding of brittle materials.
Selection of efficient coordinate partitioning methods in flexible multibody systems
Kim, Oe-Jo ; Yoo, Wan-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1311~1321
DOI : 10.22634/KSME-A.19220.127.116.111
In multibody dynamics, differential and algebraic equations which can satisfy both equation of motion and kinematic constraint equation should be solved. To solve these equations, coordinate partitioning method and constraint stabilization method are commonly used. In the coordinate partitioning method, the coordinates are divided into independent and dependent and coordinates. The most typical coordinate partitioning method are LU decomposition, QR decomposition, and SVD (singular value decomposition). The objective of this research is to find an efficient coordinate partitioning method in the dynamic analysis of flexible multibody systems. Comparing two coordinate partitioning methods, i.e. LU and QR decomposition in the flexible multibody systems, a new hybrid coordinate partitioning method is suggested for the flexible multibody analysis.
Fracture criterion of mixed mode in adhesively bonded joints of Al/Steel dissimilar materials
Jeong, Nam-Yong ; Jang, Jin-Mo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1322~1331
DOI : 10.22634/KSME-A.1918.104.22.1682
A method of strength evaluation applying fracture mechanics in the adhesively bonded joints of Al/Steel dissimilar materials was investigated in this paper. Various shapes of adhesively bonded Al/Steel scarf joints focussing on fracture criterion of mixed mode crack were prepared for the static tests. Also, stress intensity factors of the interface cracks in adhesively bonded joints of Al/Steel dissimilar materials were analyzed with 2-dimensional elastic program of boundary element method(BEM), and the experiment of fracture toughness were carried out under various mixed mode conditions. From the results, the fracture criterion and method of strength evaluation by the fracture toughness in adhesively bonded joints of Al/Steel dissimilar materials were proposed.
Active noise control with on-line adaptive algorithm in a duct system
Kim, Heung-Seob ; Hong, Jin-Seok ; Oh, Jae-Eung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1332~1338
DOI : 10.22634/KSME-A.1922.214.171.1242
In the case of the transfer function for the secondary path is dependent on time, the on-line method which can model it is continuously must be applied to the active noise control technique. And the adaptive random noise technique among the on-line methods is effective in the narrow-band control. In this method, the signal to noise ratio between random noise for modeling and primary noise is low. Therefore, the estimations of transfer function will be prone to inaccuracies and the convergence time will be too long. Such imperfections will have an influence upon the performance of an active noise controller. In this study, t enhance the signal to noise ratio, the on-line method that is combined the conventional adaptive random noise technique and the adaptive line enhancer, is proposed. By using proposed on-line method, a rigorous system identification and control of primary noise have been implemented.
The accurate measurement of center position and orientation of SMD VR by using machine vision
Jhang, Kyung-Young ; Kim, Byung-Yup ; Han, Chang-Su ; Park, Jong-Hyun ; Gam, Do-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1339~1347
DOI : 10.22634/KSME-A.19126.96.36.1999
The automation of final inspection and tuning process in the manufacturing of electric products is hot issue now, because it is the only part that has not been wholey automized yet, mainly due to the difficulties to handle so small size of VR which is the final tuning point in the most of electric products. For the automation of this process, at first the accurate measurement of position and orientation of SMD VR on PCB in real time is strongly needed. In this paper, a new image processing algorithm to detect the center position and orientation of target VR by using machine vision is proposed for automatic final tuning of the 8mm camcoder's performance. In the method, the outline feature of object is used actively. The usefulness of the proposed methods were tested by several experiments, and the results showed enough accuracy for both of position and orientation. Additatively, we discussed about the total visual system construction and preprocessing of image.
Software development for the machine element design course
Park, Gyung-Jin ; Do, Sung-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 8, 1997, Pages 1348~1355
DOI : 10.22634/KSME-A.19188.8.131.528
Machine element design is a very important course in the undergraduate program of mechanical engineering in that it presents traditional design concepts. While computer aided design(CAD) receives more attention, students tend to ignore the machine element design or traditional design concepts. However, design methodologies related to machine elements are utilized quite often in practical fields. Also, design methodologies provide good insight for the decision making process of modern design. Generally, CAD is used for simple drafting without the real design process in the undergraduate program. Design software has been developed for various machine elements. Through menu display, a user can select or furnish the design input such as design objects, dimensions, environmental forces and usages, and safety factors. Then the software carries out the design processes which are the same as those of textbooks. The result of the design is filtered to have the values in the standards. The designed machine element is drawn via commercial CAD software. The software has been developed with C language on a personal computer. The developed software is being utilized successfully in a design course, and the experiences are discussed in this paper. The software can be used in industries which require the repeated process of the machine element design.