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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 27, Issue 12 - Dec 2003
Volume 27, Issue 11 - Nov 2003
Volume 27, Issue 10 - Oct 2003
Volume 27, Issue 9 - Sep 2003
Volume 27, Issue 8 - Aug 2003
Volume 27, Issue 7 - Jul 2003
Volume 27, Issue 6 - Jun 2003
Volume 27, Issue 5 - May 2003
Volume 27, Issue 4 - Apr 2003
Volume 27, Issue 3 - Mar 2003
Volume 27, Issue 2 - Feb 2003
Volume 27, Issue 1 - Jan 2003
Selecting the target year
Formation of Switching Zones in an AFM Tip／Ferroelectric Thin Film/BE System
Kim, Sang-Joo ; Shin, Joon-Ho ; Kim, Yun-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 849~856
DOI : 10.3795/KSME-A.2003.27.6.849
A three-dimensional constitutive model for polarization switching in ferroelectric materials is used to predict the formation of switching zones in an atomic force microscopy(AFM) tip/ferroelectric thin film/bottom electrode system via finite element simulation. Initially the ferrolectric film is poled upward and the bottom electrode is grounded. A strong dc field is imposed on a fixed point of the top surface of the film through the AFM tip. A small switching zone with downward polarization is nucleated and grows with time. It is found that initially the shape of the switched zone is that of a bulgy dagger, but later turn to the shape of a reversed cup with the lower part wider than the upper part. It can also be concluded that the size of switching zones increases with the period of applied electric potential. The present results are qualitatively consistent with experimental observations.
A Study on Development the Dynamic Model to Misaligned Gear Coupling (I) - The Focus on Development of Dynamic Model to n Gear Coupling
Kim, Byung-Ok ; Kim, Yong-Chul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 857~863
DOI : 10.3795/KSME-A.2003.27.6.857
In rotating machinery, unbalance and misalignment are major concerns in vibration. Unbalance can be eliminated by balancing procedure to some degree. but little work has been done on the vibrations that occur in a misaligned rotor system. Currently, no generalized theoretical model based on a rotor system with flexible coupling is available to describe the vibrations caused by misalignment. As a part of systematic investigation on the misalignment, first of all, the study on flexible coupling with misalignment should be preceded. In this study, the geometry and reaction force and moment of a gear coupling with misalignment was investigated, also the theoretical model of a gear coupling with misalignment was presented by using the relationship between geometry and moment of gear coupling. It is expected that the proposed procedure can be applied to derive the theoretical model of other couplings.
Optimization of a Train Suspension using Kriging Model
Park, Chan-Kyoung ; Lee, Kwang-Ki ; Lee, Tae-Hee ; Bae, Dae-Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 864~870
DOI : 10.3795/KSME-A.2003.27.6.864
In recent engineering, the designer has become more and more dependent on the computer simulations such as FEM(Finite Element Method) and BEM(Boundary Element Method). In order to optimize such implicit models more efficiently and reliably, the meta -modeling technique has been developed for solving such a complex problems combined with the DACE(Design and Analysis of Computer Experiments). It is widely used for exploring the engineer`s design space and for building approximation models in order to facilitate an effective solution of multi-objective and multi-disciplinary optimization problems. Optimization of a train suspension is performed according to the minimization of forty -six responses that represent ten ride comforts, twelve derailment quotients, twelve unloading ratios, and twelve stabilities by using the Kriging model of a train suspension. After each Kriging model is constructed, multi -objective optimal solutions are achieved by using a nonlinear programming method called SQP(Sequential Quadratic Programming).
The Design and Control of Contact-free Magnetic Suspension System with Four Degrees of Freedom
Lee, Sang-Heon ; Baek, Yoon-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 871~878
DOI : 10.3795/KSME-A.2003.27.6.871
With the development of micro -technology, the demand for micro actual ing device is increasing. But, it is difficult to achieve high resolution and wide bandwidth with the conventional contact systems. So, the contact-free systems which are suspended or levitated by magnetic force or air bearing were proposed. These systems can be applied to high precision stages and alignment apparatuses. This paper describes a magnetically suspended system with four degrees of freedom which are composed of three rotations (roll, pitch, yaw), and one translation ( z). The operating principle and the structure of the system are similar to variable reluctance type electric machines. In this study, the force analysis is executed using magnetic circuit and virtual work principle, and the equations that describe the dynamics of the system are presented. The multivariable PID controller is adapted to the system and the experiment is executed.
Rocking Vibration of Rigid Block Structure Accompaning Sliding Motion - In the Case of Two Dimensional Harmonic Excitation with Different Frequencies -
Jeong, Man-Yong ; Kim, Jeong-Ho ; Yang, In-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 879~889
DOI : 10.3795/KSME-A.2003.27.6.879
This research deals with the nonlinearities of rocking vibration associated with impact and sliding on the rocking behavior of rigid block under two dimensional sinusoidal excitation which has different frequencies in two excitation direction. The varied excitation direction influences not only the rocking response but also the sliding motion and the rocking response shape. Chaotic responses are observed in wider excitation amplitude region, when the frequencies in each excitation direction are different. The complex behavior of chaotic response, in the phase space, is related with the trajectory of base excitation and sliding motion.
Creep Fracture Mechanics Analysis for Through-Wall Cracked Pipes under Widespread Creep Condition
Huh, Nam-Su ; Kim, Yun-Jae ; Kim, Young-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 890~897
DOI : 10.3795/KSME-A.2003.27.6.890
This paper compares engineering estimation schemes of C＊ and creep COD for circumferential and axial through-wall cracked pipes at elevated temperatures with detailed 3-D elastic-creep finite element results. Engineering estimation schemes included the GE/EPRI method, the reference stress method where reference stress is defined based on the plastic limit load and the enhanced reference stress method where the reference stress is defined based on the optimized reference load. Systematic investigations are made not only on the effect of creep-deformation behaviour on C＊ and creep COD, but also on effects of the crack location, the pipe geometry, the crack length and the loading mode. Comparison of the FE results with engineering estimations provides that for idealized power law creep, estimated C＊ and COD rate results from the GE/EPRI method agree best with FE results. For general creep-deformation laws where either primary or tertiary creep is important and thus the GE/EPRI method is hard to apply, on the other hand, the enhanced reference stress method provides more accurate and robust estimations for C* and COD rate than the reference stress method.
Plastic Zone Size in a Ductile Layer with an Interface Crack - Case Study for Dissimilar Substrates -
Kim, Dong-Hak ; Kang, Ki-Ju ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 898~904
DOI : 10.3795/KSME-A.2003.27.6.898
Using the modified Irwin model and the modified Dugdale model, the plastic zone size near the interface crack tip in a ductile layer bonding two dissimilar elastic substrates is predicted. Validity of the models is examined by finite element method. The effects of several factors such as the mode mixity, T-stress and material properties are explored. The plastic zone size significantly decreases with the Poisson`s ratio of the ductile layer.
Robust Optimization of Caliper Brake Disc Considering Tolerance
Kim, Jong-Hun ; Park, Jeong-Min ; Lee, Jong-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 905~913
DOI : 10.3795/KSME-A.2003.27.6.905
Generally, most of optimization have been performed with fixed sizes and variables. But, the optimum value considering tolerance of design variables and material properties, might be useless owing to exist in infeasible region. It is needed that the tolerance of design variables and material properties is considered for a real design problem. A deterministic optimal solution can be in the feasible region by performing robust optimization considering tolerance. In the paper, robust design is suggested to gain an optimum insensitive to variation of design variables and it is applied for optimization problem of caliper disc brakes for vehicles.
Non-Local Analysis of Forming Limits of Ductile Material Considering Damage Growth
Kim, Young-Suk ; Won, Sung-Yeun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 914~922
DOI : 10.3795/KSME-A.2003.27.6.914
In this paper, the strain localization of voided ductile material has been analyzed by nonlocal plasticity formulation in which the yield strength not only depends on an equivalent plastic strain measure (hardening parameter), but also on the Laplacian thereof. The gradient terms in yield criterion show an important role on modeling strain-softening phenomena of material. The influence of the mesh size on the elastic -plastic deformation behavior and the effect of the characteristic length parameter for localization prediction are also investigated. The proposed nonlocal plasticity shows that the load -strain curves converge to one curve. Results using nonlocal plasticity also exhibit the dependence of mesh size is much less sensitivity than that for a corresponding local plasticity formulation.
Probabilistic Fatigue Crack Growth Behavior under Constant Amplitude Loads
Jeong, Hyeon-Cheol ; Kim, Seon-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 923~929
DOI : 10.3795/KSME-A.2003.27.6.923
In this paper, an analysis of fatigue crack growth behavior from a statistical point of view has been carried out. Fatigue crack growth tests were conducted on sixteen pre-cracked compact tension (CT) specimens of the pressure vessel (SPV50) steel in controlled identical load and environmental conditions. The assessment of the statistical distribution of fatigue crack growth experimental data obtained from SPV50 steel was studied and also the correlation of the parameter C and m in the Paris-Erdogan law was discussed. The probability distribution function of fatigue crack growth life seems to follow the 3-parameter Weibull. The fatigue crack growth rate seems to follow the 3-parameter Weibull and the log-normal distribution. The coefficient of variation (COV) of fatigue crack growth life was observed to decrease as the crack grows. Fatigue crack growth rate data shows a normal distribution for both m and logC. A strong negative linear correlation exists between the coefficient C and the exponent m.
Integrity Evaluation for Stud Female Threads on Pressure Vessel according to ASME Code using FEM
Kim, Moon-Young ; Chung, Nam-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 930~937
DOI : 10.3795/KSME-A.2003.27.6.930
The extension of design life among power plants is increasingly becoming a world-wide trend. Kori #1 unit in Korea is operating two cycle. It has two man-ways for tube inspection in a steam generator which is one of the important components in a nuclear power plant. Especially, stud bolts fur man-way cover have damaged by disassembly and assembly several times and degradation for bolt materials for long term operation. It should be evaluated and compared by ASME Code criteria for integrity evaluation. Integrity evaluation criteria which has been made by the manufacturer is not applied on the stud bolts of nuclear pressure vessels directly because it is controlled by the yield stress of ASME Code. It can apply evaluation criteria through FEM analysis to damaged female threads and to evaluated safety fer helical-coil method which is used according to Code Case-N-496-1. From analysis results, we found .that it is the same results between stress intensity which got from FEM analysis on damaged female threads over 10％ by manufacture integrity criteria and 2／3 yield strength criteria on ASME Code. It was also confirmed that the helical-coil repair method would be safe.
A Study on the Sensor Placement for Structural Damage Detection
Choi, Young-Jae ; Lee, U-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 938~945
DOI : 10.3795/KSME-A.2003.27.6.938
In the present study, the inverse perturbation method is applied to the structural damage detection in conjunction with a system condensation technique. The system condensation technique is adopted to r esolve the problem due to the incomplete measurement of the degrees-of-freedom (DOFs) in a natural mode. However, the numerical difficulty may arise in the system condensation when the DOFs to be measured are not properly selected. Thus, the issue of sensor placement for structural damage detection, in the framework of the condensation technique-based inverse perturbation method, is considered in this study. Also, a methodology to measure the number of sensors required to obtain reliable damage detection is proposed and then verified through some illustrative example problem.
High Cycle Fatigue Damage under Multiaxial Random Loading through Dynamic Simulation for an Automotive Sub-Frame
Lee, Hak-Joo ; Kang, Jae-Youn ; Choi, Byung-Ick ; Kim, Joo-Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 946~953
DOI : 10.3795/KSME-A.2003.27.6.946
A FEM-based analytical approach was used to evaluate the multiaxial high cycle fatigue damage of an automotive sub-frame. Elastic Multi Body Simulation (MBS) has been applied in order to determine the multiaxial load histories. The stresses due to these loads have been given by FE computation. These results have been used as the input for the multiaxial fatigue analysis. For the assessment of multiaxial high cycle fatigue damage, the signed von Mises, the signed Tresca, the absolute maximum principal stress and critical plane methods have been employed. In addition, the biaxiality ratio, a
e/, the absolute maximum principal stress,
p/ and the angle,
1/ and the local x-axis, have been calculated to evaluate the stress state at each node.
Functional Colonoscope Robot System
Lim, Hun-Young ; Jeong, Youn-Koo ; Kim, Byung-Kyu ; Park, Jong-Hyeon ; Park, Jong-Oh ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 954~959
DOI : 10.3795/KSME-A.2003.27.6.954
Colonoscopy is an important medical procedure for the diagnosis of various diseases like cancers in the colon and rectum. But it requires a lot of time for a doctor to acquire dexterous skills necessary to perform successful colonoscopy. Moreover, to many patients, conventional colonoscopy simply takes too long time. Therefore, some studies on the development of autonomous and more convenient colonoscope are carried out. In this Paper, we Propose a functional colonoscope robot system that has a locomotive function with a hollow body, a steering system, and other basic functions of typical conventional colonoscope systems. The concept and each component of the functional colonoscope system are described in this paper. In order to evaluate the functional performance of the colonoscope robot, we carried out in -vitro and in-vivo tests.
AE Characteristics of Fatigue Crack Opening and Closure in SWS 490B and Al 7075-T6 Alloy
Yoon, Dong-Jin ; Jeong, Jung-Chae ; Lee, Seung-Seok ; Won, Chang-Whan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 960~968
DOI : 10.3795/KSME-A.2003.27.6.960
The objective of this study is to investigate the effect of AE activities in the crack opening and closure during the fatigue test. The laboratory experiments for various materials and test conditions were carrie out to identify AE characteristics of fatigue crack propagation. Compact tension specimens of SWS 490B and Al 7075-T6 alloy were prepared for fatigue test. AE activities were analyzed based on the phase of the loading cycle. In case of SWS 490B, the most of AE was generated when the crack began opening and the crack closed fully, whereas a few in the full opening of the crack. On the other hand, in case of Al 7075-T6, a distinct AE activity was observed during crack opening process. AE activity in the peak loading of cycle was different with each specimen. However, in the same material, AE activity was not affected by the change of cyclic frequency (0.1, 0.2, 1.0 ㎐). It was found that AE activities during crack opening and closure depend on material properties such as micro-structure, yield strength and elongation.
Analysis of Multiple Curved Cracks in An Orthotropic Plate
Kim, Maan-Won ; Park, Jai-Hak ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 969~980
DOI : 10.3795/KSME-A.2003.27.6.969
The interactions between curved cracks are examined in an orthotropic plate and the effects of rectilinear anisotropy on the stress intensity factors are analyzed. The finite element alternating method (FEAM) is used in this study to get the stress intensity factors for the multiple curved cracks. To obtain analytical solutions, which is necessary in FEAM, the curved cracks are modeled as continuous distributions of dislocations, and integral equations are formulated for unknown dislocation density functions to satisfy the given resultant forces on the crack surfaces. Several basic problems are solved to verify the accuracy and efficiency of the proposed method and it can be found that present results show good agreements with the previously published results.
The Effects of Boundary Condition in Cone Crack Formation of Soda-lime Glass by Ball Impact
Kim, Moon-Saeng ; Heo, Jin ; Lee, Hyeon-Chul ; Kim, Ho-Jong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 981~986
DOI : 10.3795/KSME-A.2003.27.6.981
In order to investigate the possibility of processing of brittle material by ball impact, the effects of boundary conditions about impact damage of soda-lime glass by small spheres were evaluated experimentally. It was investigated that crack appearance developed in soda-lime glass with boundary conditions of without sealing, single-sealing and double-sealing by impact velocity. The double-sealing was most effective in the development of perfect cone than other boundary condition. In case of double-sealing condition, PVC and Polyurethane sealing were more effective in producing a perfect cone formation than other sealing materials. The impact velocity range over which perfect cones were formed was influenced by both the contact area and diameter of impact particle.
Probabilistic Fracture Mechanics Analysis of Reactor Vessel for Pressurized Thermal Shock - The Effect of Residual Stress and Fracture Toughness -
Jung, Sung-Gyu ; Jin, Tae-Eun ; Jhung, Myung-Jo ; Choi, Young-Hwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 987~996
DOI : 10.3795/KSME-A.2003.27.6.987
The structural integrity of the reactor vessel with the approaching end of life must be assured for pressurized thermal shock. The regulation specifies the screening criteria for this and requires that specific analysis be performed for the reactor vessel which is anticipated to exceed the screening criteria at the end of plant life. In case the screening criteria is exceeded by the deterministic analysis, probabilistic analysis must be performed to show that failure probability Is within the limit. In this study, probabilistic fracture mechanics analysis of the reactor vessel for pressurized thermal shock is performed and the effects of residual stress and master curve on the failure probability are investigated.
Fabrication of Polymeric Optical Waveguide by LIGA
Kim, Jin-Tae ; Kim, Byeong-Cheol ; Choi, Choon-Gi ; Yoon, Keun-Byoung ; Jeong, Myung-Yung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 997~1006
DOI : 10.3795/KSME-A.2003.27.6.997
LICA technique evolved as a basic fabrication process fur micro-structure. The present report deals with the basic technological features in the sequence of the LIGA technique such as deep x-ray lithography(DXRL), electroplating, and moulding processes at Pohang Light Source (PLS). We designed 3-D structured master for fabrication of polymeric optical wavegude and manufactured polymeric optical wavegude with the same using hot embossing process. Polymeric optical waveguide could be produced with
accuracy and good surface roughness.
Analysis of Cooling Effect Using Compressed Cold Air in Turing Process
Kwak, Seung-Yong ; Kim, Dong-Kil ; Lee, Jong-Hang ; Lee, Sang-Jo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 1007~1013
DOI : 10.3795/KSME-A.2003.27.6.1007
As environmental restriction kas continuously become more strict, machining technology has emphasized on development of environment-friendly technology. In cutting technology, it has been well recognized that cutting fluids might have undesirable effects on workers health and working environment. In this study, compressed cold air was used as a replacement for conventional cutting fluids. The cooling effect on cutting tool was analyzed using the finite element method and the computational fluid dynamics. This study focused on the temperature simulation of cutting tool by real flow analysis of cold air. The maximum flow rate and the minimum temperature of compressed cold air are 300ι/min and -30
respectively. To compare the simulation and experimental results, inner temperature of the cutting tool was measured with the thermocouple embedded in the insert. The results show that the analysis of cutting temperature using FEM and CFD is resonable, and the replacement of cutting fluid with cold air is available.
Dynamic Modeling Method for Beams Undergoing Overall Rigid Body Motion Considering Two Geometric Non-linear Effects
Kim, Na-Eun ; Yoo, Hong-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 1014~1019
DOI : 10.3795/KSME-A.2003.27.6.1014
A dynamic modeling method for beams undergoing overall rigid body motion is presented in this paper. Two special deformation variables are introduced to represent the stretching and the curvature and are approximated by the assumed mode method. Geometric constraint equations that relate the two special deformation variables and the cartesian deformation variables are incorporated into the modeling method. By using the special deformation variables, all natural as well as geometric boundary conditions can be satisfied. It is shown that the geometric nonlinear effects of stretching and curvature play important roles to accurately predict the dynamic response when overall rigid body motion is involved.
The Optimization of Injection Molding System Using Axiomatic Approach
Kim, Jong-Hun ; Lee, Jong-Soo ; Cha, Sung-Woon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 1020~1027
DOI : 10.3795/KSME-A.2003.27.6.1020
A traditional mold design has been conducted by an experience-based trial and error, whereby the mold designer would decide the gate locations and processing conditions based on the caring characteristics and its functional requirements. The paper suggests an optimal gate location and processing conditions in the injection molding using a global search method referred to as micro genetic algorithm(
GA yields the optimal solution with a small size of population without respect to design variables for saving time that is needed to calculate the fitness of many individuals. Due to the reason, the paper uses a commercial analysis package of injection molding(CAPA) to analysis a state of flux. In addition to that, axiomatic approach .is applied in the beginning of design. It is a useful method to draw a well-organized and reasonable idea to handle a problem.
Prediction of Noise and Vibration Characteristics of Externally Pressurized Air Journal Bearings with a Circular Slot Restrictor
Rho, Byoung-Hoo ; Park, Jung-Koo ; Kim, Kyung-Woong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 1028~1033
DOI : 10.3795/KSME-A.2003.27.6.1028
The purpose of this paper is to investigate the noise and vibration characteristics of externally pressurized air journal bearings with a circular slot restrictor. To do this, the nonlinear transient analysis including rotor imbalance was performed for a rotor-bearing system. The effects of radial clearance and the length of the bearing and mass eccentricity of the rotor on the noise and vibration characteristics of the bearing are also examined. The results show that the noise and vibration of the rotor-bearing system first increase up to critical speed of the system, and then decrease up to instability threshold speed of the system as the rotational speed of the rotor increases, and the noise of the bearing is markedly influenced by the mass eccentricity of the rotor and the radial clearance and the length of the bearing.
Creep-Induced Tension Loosening of CRT Tension Mask
Chung, Il-Sup ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 1034~1040
DOI : 10.3795/KSME-A.2003.27.6.1034
Tension mask is a part of CRT type devices, which is installed right behind glass-made front panel. Numerous slits on the thin metal sheet enable the electron beams emitted from posterior gun to be focused, resulting in enhanced definition. Flattened and enlarged displays necessitate the imposition of pretension on the masks, in order to improve the robustness of display quality against vibration or impact. High temperature assembly process subsequent to pretensioning, however, degenerates creep resistance of mask material, and common mask may become susceptible to undesirable elongation due to creep. Once tensile stress becomes high enough to induce creep deformation, pretension is substantially loosened. In this study, tension mask assembly is modeled as a combined structure of beams and wire array, and a numerical simulation is attempted for pretensioning followed by high temperature process. Based on a model study, creep occurrence is found to be probable and its adverse influence is quantified. As fur maintaining high tensile force, simply increasing pretension does not seem to be helpful. Instead, the structure of frame needs to be modified somehow, or material for mask needs to be selected properly.
Design Optimization Using the Two-Point Convex Approximation
Kim, Jong-Rip ; Choi, Dong-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 6, 2003, Pages 1041~1049
DOI : 10.3795/KSME-A.2003.27.6.1041
In this paper, a new local two-point approximation method which is based on the exponential intervening variable is proposed. This new algorithm, called the Two-Point Convex Approximation(TPCA), use the function and design sensitivity information from the current and previous design points of the sequential approximate optimization to generate a sequence of convex, separable subproblems. This paper describes the derivation of the parameters associated with the approximation and the numerical solution procedure. In order to show the numerical performance of the proposed method, a sequential approximate optimizer is developed and applied to solve several typical design problems. These optimization results are compared with those of other optimizers. Numerical results obtained from the test examples demonstrate the effectiveness of the proposed method.