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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers A
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 26, Issue 12 - Dec 2002
Volume 26, Issue 11 - Nov 2002
Volume 26, Issue 10 - Oct 2002
Volume 26, Issue 9 - Sep 2002
Volume 26, Issue 8 - Aug 2002
Volume 26, Issue 7 - Jul 2002
Volume 26, Issue 6 - Jun 2002
Volume 26, Issue 5 - May 2002
Volume 26, Issue 4 - Apr 2002
Volume 26, Issue 3 - Mar 2002
Volume 26, Issue 2 - Feb 2002
Volume 26, Issue 1 - Jan 2002
Selecting the target year
A Study on Quantitative Visualization and Measurement of Physical Properties of Radial Symmetric Fluids Using Electronic Speckle Pattern Interferometry
Gang, Yeong-Jun ; Chae, Hui-Chang ; Kim, Gyeong-Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 217~224
DOI : 10.3795/KSME-A.2002.26.2.217
It is very important to measure and visualize the changes in the physical properties of fluid flow because this is the foundation of measurement techniques used in aerodynamics, heat transfer, plasma diagnostics, and stress analysis of transparent models. The optical methods are advantageous over probe-based techniques in the optical methods are of high speed, non-contact and are capable of providing full-field results with high spatial resolution. Therefore we propose the electronic speckle pattern interferometry(ESPI) that gives us a solution to overcome those limitations. In this paper the experimental results show qualitative and quantitative visualization of changes in the physical properties of the candle and alcohol lamp with 3D plotting. And we obtained the refractive index, mass density and temperature distribution of fluids. The results clearly show the process of flow phenomena and give the feasibility of quantitative interpretation of gasdynamics.
Behavior of the Flexural Vibration Damping of a Sandwich Beam System with a Partially Inserted Viscoelastic Layer
Park, Jin-Taek ; Yu, Hyeong-Won ; Jang, Seok-Won ; Choe, Nak-Sam ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 225~233
DOI : 10.3795/KSME-A.2002.26.2.225
The flexural vibration characteristics of a sandwich beam system with a partially inserted viscoelastic layer have been quantitatively studied using a finite element analysis in combination with a sine-sweep test. Antisymmetric mode shapes of the flexural vibration were visualized by the holographic interferometry and agreed with those calculated by the finite element simulation. Effects of the beam thickness as well as the length and thickness of partial viscoelastic layers on the system loss factor(η
s/) and resonant frequency(
r/) were significantly large fur the symmetric and antisymmetric modes of the beam system.
Optimal Design of Synthetic Intervertebral Disc Prosthesis Considering Nonlinear Mechanical Behavior
Gwon, Sang-Yeong ; Kim, Hyeong-Tae ; Ha, Seong-Gyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 234~242
DOI : 10.3795/KSME-A.2002.26.2.234
A shape optimal design of synthetic intervertebral disc prosthesis is performed using a three-dimensional finite element method. Geometric parameters are introduced to model the cross-sectional geometry of the intervertebral disc. It is assumed that the total strain energy in the intact intervertebral disc is minimized under the normal load conditions, as often cited in other references. To calculate the stain energy density, both the nonlinear material properties and the large deformations are taken into account. The design variables of the annulus fiber angle and the area ratio of the nucleus pulposus are calculated as 31°and 30%, respectively, which complies well with the intact disc. Thus, the same optimization procedure is applied to the design of the synthetic intervertebral disc prosthesis whose material properties are different from the intact disc. For the given synthetic material properties, the values of 67°and 24% for the fiber angle and the area ratio are obtained.
Output Feedback Sliding Mode Control System with Disturbance Observer for Rotational Inverted Pendulums
Lee, Gyu-Jun ; Ha, Jong-Heon ; Kim, Jong-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 243~253
DOI : 10.3795/KSME-A.2002.26.2.243
This paper presents the system modeling, analysis, and controller design and implementation for a rotational inverted pendulum system(RIPS), which is an under-actuated system and has the problem of unattainable angular velocity state. A sliding mode controller using the parameterization of both the hyperplane and the compensator fur output feedback is applied to the RIPS. Also, to improve the performance of the control system, a disturbance observer which estimates the disturbance, parameter variation, and some modeling errors of RIPS with less computational effort is used together. The results of simulation and experiment show that the proposed control system has superior performance for disturbance rejection and regulation at certain initial conditions.
A Comparative Study of a Variable Overlap-area Type and Conventional Types in the Inductive Precision Position Measurement System
Choe, Dong-Jun ; Choe, In-Muk ; Kim, Su-Hyeon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 254~259
DOI : 10.3795/KSME-A.2002.26.2.254
A variable air-gap type system is widely used for inductive precision position measurement systems. This type transducer has high sensitivity but lacks a linear measurement range due to structural nonlinearity. Furthermore, as measurement range increases, linearity error is also increased. The alternative is a variable overlap-area type system. The sensitivity of this type is determined by the initial air-gap dimension, keeps the original value and does not deteriorate linearity in spite of the variations of the measuring range.
A Study on Tribological Characteristics of DLC Films Considering Hardness of Mating Materials
Na, Byeong-Cheol ; Tanaka, Akihiro ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 260~266
DOI : 10.3795/KSME-A.2002.26.2.260
DLC films were deposited on Si wafer by RF plasma assisted CVD using CH4 gas. Tribological tests were conducted using rotating type ball on disk friction tester in dry air. Four kinds of mating balls were used. The mating balls were made with stainless steel but apply different annealing conditions to achieve different hardness conditions. Testing results in all load conditions showed that the harder the mating materials, the lower the friction coefficient among the three kind of martensite mating balls. In case of austenite balls, the friction coefficients were lower than fully annealed martensite ball. The high friction coefficient in soft martensite balls seems to be caused by the larger contact area between DLC film and ball. The wear tracks of DLC films and mating balls could have proven that effect. Measuring the wear track of both DLC films and mating balls have similar tendency comparing to the results of friction coefficients. Wear rate of austenite balls were also smaller than that of fully annealed martensite ball. The results of effect of applying load showed, the friction coefficients were become decrease when the applying loads exceed critical load conditions. The wear track of mating balls showed that some material transfer occurs from DLC film to mating ball during the high friction process. Raman spectra analysis showed that transferred material was a kind of graphite and contact surface of DLC film seems to undergo phase transition from carbon to graphite during the high friction process.
Experimental Verification of Flexible Multibody Dynamic Simulations for A Rotating Beam
Kim, Seong-Su ; Gang, Yeon-Jun ; Lee, Gyu-Il ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 267~274
DOI : 10.3795/KSME-A.2002.26.2.267
Using a flexible rotating beam test bed, experimental verification of a flexible multibody dynamic simulations for a rotating beam model has been carried out. The test bed consists of a flexible arm, harmonic driver reducer, AC servo motor and DSP board with PC. The mechanical ports of the test bed has been designed using 3D CAD program. For the simulation model, mass and moment of inertia of each part of the flexible rotating beam test bed are also obtained from 3D CAD model. In the flexible multibody dynamic simulations, the substructuring model has been established to capture nonlinear effects of the flexible rotating beam. Through the experimental verification, substructuring model provides better results than those from the linear model in the high speed rotation.
Fracture Characteristic of TiNi/A16061 Share Memory Alloy Composite using Acoustic Emission Technique
Lee, Jin-Kyung ; Park, Young-Chul ; Ku, Hoo-Taek ; Park, Dong-Sung ; Lee, Kyu-Chang ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 275~282
DOI : 10.3795/KSME-A.2002.26.2.275
Tensile residual stress happen by difference of coefficients of thermal expansion between fiber and matrix is one of the serious problems in metal matrix composite(MMC). In this study, TiNi fiber was used to solve the tensile residual stress as the reinforced material. TiNi fiber improves the tensile strength of composite by occurring compressive residual stress in matrix using shape memory effect of it. Pre-strain was added to generate compressive residual stress inside TiNi/A16061 composite. It was also evaluated the effect of compressive residual stress corresponding to pre-strains variation. AE technique was used to clarify the microscopic damage behavior at high temperature and the effect of pre-strain difference of TiNi/A16061 shape memory alloy composite.
Steady State Crack Propagation Behavior in a Piezoelectric Strip Bonded to Elastic Materials
Gwon, Sun-Man ; Choe, Hyo-Seung ; Lee, Gang-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 283~290
DOI : 10.3795/KSME-A.2002.26.2.283
In this paper, we consider the dynamic electromechanical behavior of an eccentric Yoffe permeable crack in a piezoelectric ceramic strip sandwiched between two elastic orthotropic materials under the combined anti-plane mechanical shear and in-plane electrical loadings. Fourier transforms are used to reduce the problem to the solution of two pairs of dual integral equations, which are then expressed to a Fredholm integral equation of the second kind. The initial crack propagation orientation for PZT-5H piezoceramics is predicted by maximum energy release rate criterion.
Characterization of Bi-directionally Oscillating Microflow and Flow Rectification Performance of Microdiffusers
Lee, Yeong-Ho ; Gang, Tae-Gu ; Jo, Yeong-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 291~299
DOI : 10.3795/KSME-A.2002.26.2.291
This paper characterizes hi-directionally oscillating flow in planar microdiffusers in order to evaluate the frequency-dependent flow rectification performance of the microdiffusers. In the theoretical study, we analyze a hi-directionally oscillating flow in the planar microdiffuser. In the experimental study, we fabricate two different microdiffuser prototypes, having different neck widths of 100 ㎛ (D100) and 300 ㎛(D300), respectively. The experimental net flow rates are measured as 116.6
ι/min. and 344.4
ι/min. for D100 and D300, respectively. The experimental flow rate of D300 decreases at the oscillating flow frequencies higher than 90Hz, at which the net boundary layer thickness is reduced to the microdiffuser neck width. It is experimentally verified that the flow rectification performance and the net flow rate of the microdiffusers tend to decrease when the boundary layer thickness is smaller than the diffuser neck width.
Fracture Analysis of Thick Plate for Partial Penetration Multi-pass Weldment Using J-integral
Kim, Seok ; Song, Jeong-Il ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 300~307
DOI : 10.3795/KSME-A.2002.26.2.300
Partial penetration welding joint is defined as groove welds welded from one side, without steel backing or groove welds welded from both sides but without back gouging. So it has an unwelded portion at the root of the weld. Study of partial penetration weldment fracture behavior includes residual stress analysis and fracture analysis. The J-integral loses its path independency in residual stress field. Therefore, it is necessary to introduce a new J-integral, J, which is defined including the effect of plastic deformation and thermal strain. In this study, theoretical formulation and program were developed for the evaluation of J-integral for the crack tip located in the weldment. Evaluations of fracture behavior were performed for partial penetration multi-pass weldment of 25.4mm thick plate by J-integral. From a point of fracture in partial penetration multi-pass welding, it seemed to be better to control root face smaller than 6.35mm.
A Study on the Stress Analysis for Design of Composite Material Shafts of Small Boats
Kim, Yun-Hae ; Im, Cheol-Mun ; Bae, Chang-Won ; Wang, Ji-Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 308~313
DOI : 10.3795/KSME-A.2002.26.2.308
It is known that the composite material shafts using on small boats have various advantages comparing to forged steel shafts, fur examples, specific strength, fatigue strength, corrosion, etc. The analysis of the stresses and strains in the composite material shafts made by filament winding method is presented in this paper. The classical laminated plate theory is applied on the patch cut from the composite material hollow shafts. It is verified that the composite material hollow shafts of diameter 40 mm is the most optimum when the ratio of the inner diameter to the outer is 0.4 and winding angle is 45
. It is also proven that the shear strain does not change seriously between 30
of winding angles. It is dangerous when the winding angle is over 75
because the values of shear strain and stress produced on the shaft are too high so it must be avoided to wind the filament by the angle over 75
Flexible Loop Wheel Mechanism for Intestine Movement
Im, Hyeong-Jun ; Min, Hyeon-Jin ; Kim, Byeong-Gyu ; Kim, Su-Hyeon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 314~321
DOI : 10.3795/KSME-A.2002.26.2.314
An endoscope is usually inserted into the human body for the inspection of the gullet, stomach, and large intestine (colon) and this may cause discomfort to patients and damage to tissues during diagnostic or therapeutic procedures. This situation necessitates a self-propelling endoscope. There are many kinds of mechanism to move in a rigid pipe. However, these methods are difficult to apply directly to the endoscope. The main reason is that human intestine cannot be considered as a uniform, straight, and rigid pipe. This paper proposes a flexible loop wheel mechanism, which is adaptable to the human intestine. This mechanism is designed and fabricated by a simple modeling, and tested by an experiment. Finally, the actuator is inserted into the pig colon.
Influence of Electrical Conductivity of Dielectric on Machinability of W-EDM
Kim, Chang-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 322~328
DOI : 10.3795/KSME-A.2002.26.2.322
In wire-electrical discharge machining (W-EDM), the dielectric plays an important role as the working fluid. It affects the material removal rate and the properties of the machined surface. This paper deals with the effects of the electrical conductivity of dielectric and cobalt percentage of sintered carbides on the machining characteristics and the machined surface integrities with deionized water as dielectric. A series of experiments have been performed on sintered carbides having different cobalt contents. Experimental results show that a higher cobalt content of WC decreases the metal removal rate and worsens the surface quality. Lower electrical conductivity of the dielectric results in a higher metal removal rate as the gap between wire electrode and workpiece reduced. Especially, the surface integrities of rough-cut workpiece, wire electrode, and debris were analyzed also through scanning electron microscopy(SEM) and surface roughness tester. By energy dispersive spectrometry(EDS), it is confirmed that micro cracks and some of electrode material are found on the workpiece surface.
A Study on Rudder-Roll Stabilization System Design for Ship
Kim, Yeong-Bok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 329~339
DOI : 10.3795/KSME-A.2002.26.2.329
In ship operation the consequency of roll motions can seriously degrade the performance of mechanical and personnel effectiveness. So many studies for the roll stabilization control system design have been performed and very good results have been achieved. In many studies, the stabilizing fins are used. Recently rudders, which have been extensively modified, have been used to exclusively to stabilize the roll. This paper examines the two-degree-of-freedom servosystem design technique to synthesize the yaw control system which achieves the course keeping object of the ship and the H
control approach to suppress the roll motion, respectively.
Deformation Analysis of Injection Molded Articles due to In-mold Residual Stress and Subsequent Cooling after Ejection
Yang, Sang-Sik ; Gwon, Tae-Heon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 340~348
DOI : 10.3795/KSME-A.2002.26.2.340
Deformation analysis of injection molded articles whose geometry is considered as the assembly of thin flat plates has been conducted. For the in-mold analysis, thermo-viscoelastic stress calculation of thermo-rheologically simple amorphous polymer and in-mold deformation calculation considering the in-plane mold constraint have been done. Free volume theory has been used to represent the non-equilibrium density state during the fast cooling. At ejection, instantaneous deformation takes place due to the redistribution of in-mold residual stress. During out-of-mold cooling after ejection, thermoelastic model based on the effective temperature has been adopted for the calculation of out-of-mold deformation. In this study, emphasis is also made on the treatment with regard to lateral constraint types during molding process. Two typical mold geometries are used to test the numerical simulation modeling developed in this study.
Creep Behavior Analysis of 25Cr-20Ni Stainless Steels by Omega Method
Park, In-Deok ; Nam, Gi-U ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 349~356
DOI : 10.3795/KSME-A.2002.26.2.349
For two kinds of 25Cr-20Ni stainless steels, STS310J1TB and STS310S with and without a small amount of Nb and N, creep behavior has been studied in a stress and temperature range from 147 to 392 MPa and from 923 to 773 K with a special reference to tertiary creep. The average creep life of STS310J1TB was about 100 times longer than that of the STS310S. The apparent activation energy for the initial creep rate was 330 kJ/mol in STS310J1TB, while that of the STS310S was 274kJ/mol in a power law creep region and 478 kJ/mol in a region of power law breakdown (PLB). The activation energy for STS310S below PLB is close to the for self-diffusion. When compensating for the temperature dependence of the Young's modulus and the omega value, it was found that the apparent activation energy for STS310J1TB was reduced to the activation energy for diffusion of chromium atom in gamma steel. The stress exponent of STS310S was about 12.3 above PLB and 5.1 in a power law creep region. Notwithstanding that the creep condition for STS310J1TB was in a power law creep region, its stress exponent was 7.9 larger than that of STS310S corresponding to the same creep conditions. This was ascribed to the presence of fine precipitates in STS310J1TB.
Control of Robot Manipulators Using Chattering-Free Sliding Mode
Lee, Gyu-Jun ; Gyeong, Tae-Hyeon ; Kim, Jong-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 357~364
DOI : 10.3795/KSME-A.2002.26.2.357
A new chattering free sliding made control is proposed for robot manipulators. The control input is derived from the reaching law and the Lyapunov stability criteria, which is only composed of continuous terms. It has a chattering free characteristics and a concise farm. In implementing procedures, no change of equations is needed. Thus, it does not degrade the original merits of the sliding mode control. And it is applied to a 2-link SCARA robot manipulator. It is shown that the proposed control has good trajectory tracking performance compared with the PD control and the conventional sliding mode control which uses the boundary layer concept.
Life Evaluation of Gas Turbine Engine Disk based on Retirement for Cause Concept
Nam, Seung-Hun ; Park, Jong-Hwa ; Kim, Jong-Yeop ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 365~373
DOI : 10.3795/KSME-A.2002.26.2.365
For gas turbine engines, the safe life methodology has historically been used fur fatigue life management of failure critical engine components. The safe retirement limit is necessarily determined by a conservative life evaluation procedure, thereby many components which have a long residual life are discarded. The objective of this study is to introduce the damage tolerant design concept into the life management for aircraft engine component instead of conservative fatigue life methodology which has been used for both design and maintenance. Crack growth data were collected on a nickel base superalloy which have been subjected to combined static and cyclic loading at elevated temperatures. Stress analysis fur turbine disk was carried out. The program for computing creep-fatigue crack growth was developed. The residual lifes of turbine disk component under various temperatures and conditions using creep-fatigue crack growth data were estimated. As the result of analysis, it was confirmed that retirement fur cause concept was applicable to the evaluation of residual life of retired turbine disk which had been designed based on the conventional fatigue life methodology.
Properties of Fatigue Crack Initiation and Arrest in Structural Steel Under Acid Fog
Kim, Min-Geon ; Kim, Jin-Hak ; Kim, Myeong-Seop ; Ji, Jeong-Geun ; Gu, Eun-Hoe ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 374~379
DOI : 10.3795/KSME-A.2002.26.2.374
Corrosion fatigue tests were carried out to clarify the influence of acid fog as environmental factor on the fatigue strength of SM55C using rotary bending fatigue tester. The fatigue strength of acid fog specimen extremely decreased about 80% compared to that of distilled water specimen. In acid fog environment, a number of cracks commenced at corrosion pit and coalesced with the adjacent cracks during they propagate, and they formed a single non-propagating circumferential crack under the endurance stress of N=5
7/ cycles. Also, the depth of the crack is smaller than that of normal fatigue crack, so the crack has a veil small aspect ratio. The reason of this peculiar crack growth characteristics is that the crack opening-closure behaviors are hindered by corrosion products on the surface crack faces, and hence it is thinkable that the strong corrosion action like anodic dissolution for crack growth in depth direction is weaker compared with surface, resulting from faint pumping action of crack during loading-shedding processes.
Variation of Cone Crack Shape in Ceramic Materials According to Spherical Impact Velocity
O, Sang-Yeop ; Sin, Hyeong-Seop ; Seo, Chang-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 380~386
DOI : 10.3795/KSME-A.2002.26.2.380
Damage behaviors induced in silicon carbide by an impact of particle having different material and size were investigated. Especially, the influence of the impact velocity of particle on the cone crack shape developed was mainly discussed. The damage induced by spherical impact was different depending on the material and size of particles. Ring cracks on the surface of specimen were multiplied by increasing the impact velocity of particle. The steel particle impact produced larger ring cracks than that of SiC particle. In the case of high velocity impact of SiC particle, radial cracks were produced due to the inelastic deformation at the impact site. In the case of the larger particle impact, the damage morphology developed was similar to the case of smaller particle one, but a percussion cone was farmed from the back surface of specimen when the impact velocity exceeded a critical value. The zenithal angle of cone cracks developed into SiC material decreased monotonically with increasing of the particle impact velocity. The size and material of particle influenced more or less on the extent of cone crack shape. An empirical equation,
/, was obtained as a function of impact velocity of the particle, based on the quasi-static zenithal angle of cone crack. It is expected that the empirical equation will be helpful to the computational simulation of residual strength in ceramic components damaged by the particle impact.
Impact Damage of Honeycomb Sandwich Antenna Structures
Kim, Cha-Gyeom ; Lee, Ra-Mi ; Park, Hyeon-Cheol ; Hwang, Un-Bong ; Park, Wi-Sang ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 387~398
DOI : 10.3795/KSME-A.2002.26.2.387
The impact response and damage of CLAS panel was investigated experimentally. The facesheet material used was RO4003 woven-glass hydrocarbon/ceramic and the core material was Nomex honeycomb with a cell size of 3.2mm and a density of 96 kg/㎥. The shield plane used was RO4003 and 2024-T3 aluminum. Static indentation and impact test was conducted to characterize the type and extent of the damage observed in two CLAS panels, and the performance of antenna used in a wireless LAN system. Correlation of peak contact force, residual indentation and the delamination area shows impact damage of the panel with an aluminum shield plane is larger than that of the panel with RO4003 shield plane, although the former is more penetration resistant. The damage was observed by naked eye, ultrasonic inspection and cross sectioning. The shape and size of delamination was estimated by ultrasonic inspection, and the area of delamination linearly increases as impact energy increases. The performance of impact damaged antenna was estimated by measuring return loss and radiation pattern. It was revealed that the performance of antenna was related to the impact damage and there was a threshold that the performance of antenna fell as impact energy level changed. The threshold was between the impact energies of 1.5J and 1.75J.
Pressure Control of a Piezoactuator-Driven Pneumatic Valve System
Jo, Myeong-Su ; Yu, Jung-Gyu ; Choe, Seung-Bok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 399~405
DOI : 10.3795/KSME-A.2002.26.2.399
This paper proposes a new type of piezoactuator-driven valve system. The piezoceramic actuator bonded to both sides of a flexible beam surface makes a movement required to control the pressure at the flapper-nozzle of a pneumatic valve system. After establishing a dynamic model, an appropriate size of the valve system is designed and manufactured. Subsequently, a robust H
control algorithm is formulated in order to achieve accurate tracking control of the desired pressure. The controller is experimentally realized and control performance for the sinusoidal pressure trajectory is presented in time domain. The control bandwidth of the valve system, which directly represents the fastness, is also evaluated in the frequency domain.
Convergence Enhanced Successive Zooming Genetic Algorithm far Continuous Optimization Problems
Gwon, Yeong-Du ; Gwon, Sun-Beom ; Gu, Nam-Seo ; Jin, Seung-Bo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 2, 2002, Pages 406~414
DOI : 10.3795/KSME-A.2002.26.2.406
A new approach, referred to as a successive zooming genetic algorithm (SZGA), is Proposed for identifying a global solution for continuous optimization problems. In order to improve the local fine-tuning capability of GA, we introduced a new method whereby the search space is zoomed around the design point with the best fitness per 100 generation. Furthermore, the reliability of the optimized solution is determined based on the theory of probability. To demonstrate the superiority of the proposed algorithm, a simple genetic algorithm, micro genetic algorithm, and the proposed algorithm were tested as regards for the minimization of a multiminima function as well as simple functions. The results confirmed that the proposed SZGA significantly improved the ability of the algorithm to identify a precise global minimum. As an example of structural optimization, the SZGA was applied to the optimal location of support points for weight minimization in the radial gate of a dam structure. The proposed algorithm identified a more exact optimum value than the standard genetic algorithms.