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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 30, Issue 12 - Dec 2006
Volume 30, Issue 11 - Nov 2006
Volume 30, Issue 10 - Oct 2006
Volume 30, Issue 9 - Sep 2006
Volume 30, Issue 8 - Aug 2006
Volume 30, Issue 7 - Jul 2006
Volume 30, Issue 6 - Jun 2006
Volume 30, Issue 5 - May 2006
Volume 30, Issue 4 - Apr 2006
Volume 30, Issue 3 - Mar 2006
Volume 30, Issue 2 - Feb 2006
Volume 30, Issue 1 - Jan 2006
Selecting the target year
A Study on Fracture Toughness with Thermal Aging in CF8M/SA508 Welds
Woo Seung-Wan ; Choi Young-Hwan ; Kwon Jae-Do ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1173~1178
DOI : 10.3795/KSME-A.2006.30.10.1173
In a primary reactor cooling system(RCS), a dissimilar weld zone exists between cast stainless steel(CF8M) in a pipe and low-alloy steel(SA508 cl.3) in a nozzle. Thermal aging is observed in CF8M as the RCS is exposed for a long period of time to a reactor operating temperature between 290 and
, while no effect is observed in SA508 cl.3. The specimens are prepared by an artificially accelerated aging technique maintained for 300, 1800 and 3600 hrs at
, respectively. The specimens for elastic-plastic fracture toughness tests are according to the process in the thermal notch is created in the heat affected zone(HAZ) of CF8M and deposited zone. From the experiments, the
value notched in HAZ of CF8M presented a rapid decrease up to 300 hours at
and slowly decreased according to the process in the thermal aging time. Also, the
value presented a lower value than that of the CF8M base metal. And, the
of the deposited zone presented the lowest value of all other cases.
Evaluation of Adhesion Properties of Arc PVD Coatings on Non-Nitrided and Nitrided Various Substrates
Lee Jung-Min ; Jun Sung-Jin ; Ko Dae-Cheol ; Kim Byung-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1179~1186
DOI : 10.3795/KSME-A.2006.30.10.1179
This paper was designed to assess the adhesive properties of hard coatings on non-nitrided and nitrided various tool steels. Estimations of adhesion were done to scratch test which is mainly used in hard coating. The critical load
between coating and substrate is defined through analysis of frictional load vs. normal load curve, signals of acoustic emission and optical observations. Coatings employed in this study are TiN, CrN and TiAlN, tools as substrates are STD11, STD61 and SKH51. It was classified to substrates with/without intermediate nitrided layer and hard coatings on substrate were deposited by arc PVD. Results showed that harder substrates and coatings give higher values of critical loads.
Ground Beam Structure Based Joint Stiffness Controlling Method for Compliant Mechanisms
Jang Gang-Won ; Kim Yoon-Young ; Kim Myung-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1187~1193
DOI : 10.3795/KSME-A.2006.30.10.1187
Traditionally, the continuum-based topology optimization methods employing the SIMP technique have been used to design compliant mechanisms. Although they have been successful, the optimized mechanisms by the methods are usually difficult to manufacture because of their geometrical complexities. The objective of this study is to develop a topology optimization method that can produce easy-to-fabricate mechanism structure. The proposed method is a ground beam method where beam connectivity is controlled by the beam joint stiffness. In this approach, beam joint stiffness determines the mechanism configuration. Because b the ground structure beams have uniform thicknesses varying only discretely, the resulting mechanism topologies become easily manufacturable.
An Investigation of Dynamic Characteristics of Structures Subjected to Dynamic Load from the Viewpoint of Design
Lee Hyun-Ah ; Kim Yong-Il ; Kang Byung-Soo ; Kim Joo-Sung ; Park Gyung-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1194~1201
DOI : 10.3795/KSME-A.2006.30.10.1194
All the loads in the real world are dynamic loads and structural optimization under dynamic loads is very difficult. Thus the dynamic loads are often transformed to static loads by dynamic factors, which are believed equivalent to the dynamic loads. However, due to the difference of load characteristics, there can be considerable differences between the results from static and dynamic analyses. When the natural frequency of a structure is high, the dynamic analysis result is similar to that of static analysis due to the small inertia effect on the behavior of the structure. However, if the natural frequency of the structure is low, the inertia effect should not be ignored. Then, the behavior of the dynamic system is different from that of the static system. The difference of the two cases can be explained from the relationship between the homogeneous and the particular solutions of the differential equation that governs the behavior of the structure. Through various examples, the difference between the dynamic analysis and the static analysis are shown. Also dynamic response optimization results are compared with the results with static loads transformed from dynamic loads by dynamic factors, which show the necessity of the design considering dynamic loads.
Pressure Control Valve using Proportional Electro-magnetic Solenoid Actuator
Ham Young-Bog ; Park Pyoung-Won ; Yun So-Nam ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1202~1208
DOI : 10.3795/KSME-A.2006.30.10.1202
This paper presents an experimental characteristics of electro-hydraulic proportional pressure control valve. In this study, poppet and valve body which are assembled into the proportional solenoid were designed and manufactured. The constant force characteristics of proportional solenoid actuator in the control region should be independent of the plunger position in order to be used to control the valve position in the fluid flow control system. The stroke-force characteristics of the proportional solenoid actuator is determined by the shape (or parameters) of the control cone. In this paper, steady state and transient characteristics of the solenoid actuator for electro-hydraulic proportional valve are analyzed using finite element method and it is confirmed that the proportional solenoid actuator has a constant attraction force in the control region independently on the stroke position. The effects of the parameters such as control cone length, thickness and taper length are also discussed.
Optimal Tuning of Biaxial Servomechanisms Using a Cross-coupled Controller
Bae Ho-Kyu ; Chung Sung-Chong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1209~1218
DOI : 10.3795/KSME-A.2006.30.10.1209
Precision servomechanisms are widely used in machine tool, semiconductor and flat panel display industries. It is important to improve contouring accuracy in high-precision servomechanisms. In order to improve the contouring accuracy, cross-coupled control systems have been proposed. However, it is very difficult to select the controller parameters because cross-coupled control systems are multivariable, nonlinear and time-varying systems. In this paper, in order to improve contouring accuracy of a biaxial servomechanism, a cross-coupled controller is adopted and an optimal tuning procedure based on an integrated design concept is proposed. Strict mathematical modeling and identification process of a servomechanism are performed. An optimal tuning problem is formulated as a nonlinear constrained optimization problem including the relevant controller parameters of the servomechanism. The objective of the optimal tuning procedure is to minimize both the contour error and the settling time while satisfying constraints such as the relative stability and maximum overshoot conditions, etc. The effectiveness of the proposed optimal tuning procedure is verified through experiments.
Plastic Displacement Estimates in Creep Crack Growth Testing
Huh Nam-Su ; Yoon Kee-Bong ; Kim Yun-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1219~1226
DOI : 10.3795/KSME-A.2006.30.10.1219
The ASTM test standard recommends the use of the compact tension specimen for creep crack growth rates measurement. In the creep crack growth rate test, the displacement rate due to creep is obtained by subtracting the contribution of elastic and plastic components from the total load line displacement rate based on displacement partitioning method fur determining
, which involves Ramberg-Osgood (R-O) fitting procedures. This paper investigates the effect of the R-O fitting procedures on plastic displacement rate estimates in creep crack growth testing, via detailed two-dimensional and three-dimensional finite element analyses of the standard compact tension specimen. Four different R-O fitting procedures are considered; (i) fitting the entire true stress-strain data up to the ultimate tensile strength, (ii) fitting the true stress-strain data from 0.1% strain to 0.8 of the true ultimate strain, (iii) fitting the true stress-strain data only up to 5% strain, and (iv) fitting the engineering stress-strain data. It is found that the last two procedures provide reasonably accurate plastic displacement rates and thus should be recommended in creep crack growth testing. Moreover, several advantages of fitting the engineering stress-strain data over fitting the true stress-strain data only up to 5% strain are discussed.
Prediction of Strain Energy Function for Butyl Rubbers
Kim Nam-Woong ; Kim Kug-Weon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1227~1234
DOI : 10.3795/KSME-A.2006.30.10.1227
Up to now, several mathematical theories based on strain energy functions have been developed for rubber materials. These theories, coupled with the finite element method, can be used very effectively by engineers to analyze and design rubber components. However, due to the complexities of the mathematical formulations and the lack of general guidelines available fur the analysis of rubber components, it is a formidable task for an engineer to analyze rubber components. In this paper a method for predicting strain energy functions - Neo-Hookean model and Mooney-Rivlin model - from the hardness using the empirical equation without any experiment is discussed. First based on the elasticity theories of rubber, the relation between stress and strain is defined. Then for the butyl rubbers, the model constants of Neo-Hookean model and Mooney-Rivlin model are calculated from uniaxial tension tests. From the results, the usefulness of the empirical equation to estimate elastic modulus from hardness is confirmed and, fur Mooney-Rivlin model, the predicted and the experimental model constants are compared and discussed.
Development of 3-Dim Simplified ALE Hydrocode: Application to Taylor Impact Test
Chung Wan-Jin ; Lee Min-Hyung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1235~1241
DOI : 10.3795/KSME-A.2006.30.10.1235
A new hydrocode which is still under development using Lagrangian, Eulerian and arbitrary Lagrangian-Eulerian operators, has been described. The three operators are implemented into a single framework by incorporating the sequential three stages of Lagrangian, remesh and remap stages. Several numerical schemes used for each operator are discussed briefly in this paper. In order to evaluate the characteristics of each operator, the Taylor Impact Test has been simulated using each operator and the results are compared. Currently the code is 1st order accuracy in the material interface tracking algorithm and can not handle multimaterial in the mixed cell. The areas of possible enhancement of the code are also discussed.
Densification Behavior of Nanocrystalline Ceramic Powder under Cold Compaction
Lee Sung-Chul ; Kim Ki-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1242~1248
DOI : 10.3795/KSME-A.2006.30.10.1242
Densification behavior of nanocrystalline titania powder was investigated under cold compaction. Experimental data were obtained under triaxial compression with various loading conditions. Lee and Kim proposed the Cap model by developing the parameters involved in the yield function of general Cap model and volumetric strain evolution under cold isostatic pressing. The parameters in the Drucker/Prager Cap model and the proposed model were obtained from experimental data under triaxial compression. Finite element results from the models were compared with experimental data for densification behavior of nanocystalline ceramic powder under cold isostatic pressing and die compaction. The proposed model agreed well with experimental data under cold compaction, but the Drucker/Prager Cap model underestimated at the low density range. Finite element results, also, show the relative density distribution of nanocystalline ceramic powder compacts is severe compared to conventional micron powder compacts with the same averaged relative density.
Robust Adaptive Observer Design for a Class of Nonlinear Systems via an Optimization Method
Jung Jong-Chul ; Huh Kun-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1249~1254
DOI : 10.3795/KSME-A.2006.30.10.1249
Existing adaptive observers may cause the parameter drifts due to disturbances even if state estimation errors remain small. To avoid the drift phenomena in the presence of bounded disturbances, several robust adaptive observers have been introduced addressing bounds in state and parameter estimates. However, it is not easy for these observers to manipulate the size of the bounds with the selection of the observer gain. In order to reduce estimation errors, this paper introduces the (equation omitted) gain minimization problem in the adaptive observer structure, which minimizes the (equation omitted) gain between disturbances and estimation errors. The stability condition of the adaptive observer is reformulated as a linear matrix inequality, and the observer gain is optimally chosen by solving the convex optimization problem. The estimation performance is demonstrated through a numerical example.
Coalescence Pressure of Steam Generator Tubes with Two Different-Sized Collinear Axial Through-Wall Clacks
Huh Nam-Su ; Chang Yoon-Suk ; Kim Young-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1255~1260
DOI : 10.3795/KSME-A.2006.30.10.1255
To maintain the structural integrity of steam generator tubes, 40% of wall thickness plugging criterion has been developed. The approach is for the steam generator tube with single crack, so that the interaction effect of multiple cracks can not be considered. Although, recently, several approaches have been proposed to assess the integrity of steam generator tube with two identical cracks whilst actual multiple cracks reveal more complex shape. In this paper, the coalescence pressure of steam generator tube containing multiple cracks of different length is evaluated based on the detailed 3-dimensional (3-D) elastic-plastic finite element (FE) analyses. In terms of the crack shape, two collinear axial through-wall cracks with different length were considered. Furthermore, the resulting FE coalescence pressures are compared with FE coalescence pressures and experimental results for two identical collinear axial through-wall cracks to quantify the effect of crack length ratio on failure behavior of steam generator tube with multiple cracks. Finally, based on 3-D FE results, the coalescence evaluation diagrams were proposed.
PDMS/Glass Serpentine Microchannel Chip for PCR with Bubble Suppression in Sample Injection
Cho Chul-Ho ; Cho Woong ; Hwang Seung-Yong ; Ahn Yoo-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1261~1268
DOI : 10.3795/KSME-A.2006.30.10.1261
This paper reports low-cost microreactor
biochip for the DNA PCR (polymerase chain reaction). The microbiochip
is a hybrid type which is composed of PDMS (polydimethylsiloxane) layer with serpentine micochannel
chamber and glass substrate integrated with microheater and thermal microsensor. Undesirable bubble is usually created during sample loading to PMDS-based microchip because of hydrophobic chip surface. Created bubbles interrupt stable biochemical reaction. We designed improved microreactor chamber using microfluidic simulation. The designed reactor has a coner-rounded serpentine channel architecture, which enables stable injection into hydrophobic surface using micropipette only. Reactor temperature needed to PCR reaction is controlled within
by PID controller of LabVIEW software. It is experimentally confirmed that SRY gene PCR by the fabricated microreactor chip is performed for less than 54 min.
Effect of Bend Angle on the Collapse Behavior of Locally Wall Thinned Pipe Bends
Na Man-Gyun ; Kim Jin-Weon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1269~1275
DOI : 10.3795/KSME-A.2006.30.10.1269
The purpose of this study is to investigate the effect of bend angle on the collapse behavior of locally wall thinned pipe bends. For this purpose, the present study performed three-dimensional finite element analysis on the 30-, 60-, and 90-degree pipe bends with local wall thinning at the center of intrados, extrados, and crown, and evaluated the collapse moment for different thinning dimensions under closing- and opening-mode bending with a constant internal pressure. The results showed that, for intrados and extrados wall thinning, the reduction in the collapse moment due to local wall thinning became significant with decreasing bend angle of pipe bends. This effect of bend angle was enhanced with increasing thinning dimensions, and it was clearer fur opening-mode bending than for closing-mode bending. For crown wall thinning, however, the effect of bend angle was unclear and was less sensitive to the change of wall thinning shapes.
Development and Performance Evaluation of ESP Systems for Enhancing the Lateral Stability During Cornering
Boo Kwang-Suck ; Song Jeong-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1276~1283
DOI : 10.3795/KSME-A.2006.30.10.1276
This study proposes two ESP systems which are designed to enhance the lateral stability of a vehicle. A BESP uses an inner rear wheel braking pressure controller, while a EBESP employs an inner rear wheel and front outer wheel braking pressure controller. The performances of the BESP and EBESP are evaluated for various road conditions and steering inputs. They reduce the slip angle and eliminate variation in the lateral acceleration, which increase the controllability and stability of the vehicle. However EBESP enhances the lateral stability and comfort. A driver model is also developed to control the steer angle input. It shows good performances because the vehicle tracks the desired lane very well.
Analysis of the Carburizing Heat Treatment Process for SNCM Alloy Steel Using the Finite Element Method
Choi S.C. ; Lee D.J. ; Kim H.Y. ; Kim H.J. ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1284~1292
DOI : 10.3795/KSME-A.2006.30.10.1284
Heat treatment is a controlled heating and cooling process to improve the physical and/or mechanical properties of metal products without changing their shapes. Today finite element method is widely used to simulate lots of manufacturing processes including heat treatment and surface hardening processes, which aims to reduce the number of time- and cost-consuming experimental tryouts. In this study we tried, using this method, to simulate the full carburizing process that consists of carburizing, diffusing and quenching, and to predict the distribution of carbon contents, phase fraction and hardness, thermal deformation and other mechanical characteristics as the results. In the finite element analysis deformation, heat transfer, phase transformation and diffusion effects are taken into consideration. The carburizing process of a lock gear, a part of the car seat recliner, that is manufactured by the fine blanking process is adopted as the analysis model. The numerical results are discussed and partly compared with experimental data. And a combination of process parameters that is expected to give the highest surface hardness is proposed on the basis of this discussion.
Kinematic Analysis of a Double-Action Link-Type Die Set for the Enclosed Die Forging
Park Rae-Hun ; Jun Byoung-Yoon ; Lee Min-Cheol ; Joun Man-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1293~1297
DOI : 10.3795/KSME-A.2006.30.10.1293
In this paper, kinematic analysis of a double-action link-type die set for enclosed die forging is carried out. The structure of the die set and its operational principle during enclosed die forging are introduced in detail. A closed-form solution of the relative velocity of the middle plate with respect to the upper plate after the upper and lower dies are enclosed is given in terms of the link lengths and the distance from the lower pin to the upper pin of the link system. The effect of the link lengths on both strokes and velocities is investigated. It has been shown that the relative velocity of the middle plate with respect to the upper plate varies almost linearly with the stroke of the upper plate.
An Analysis for Failure Mechanisms and Strength Evaluation on Brazed Joint
Kang Ki-Weon ; Shim Hee-Jin ; Lee Byung-Jei ; Jhang Kyung-Yung ; Kim Jung-Kyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1298~1304
DOI : 10.3795/KSME-A.2006.30.10.1298
The present paper is aiming at the evaluation for failure mechanisms and static strength of brazed joints used in household electronics. For these purposes, the failure analysis was performed on the various brazed joints, through the bursting, the micro-Victors hardness tests and 3-dimensional X-ray technique. The failure modes of brazed joints were classified into two different types, based on the results of bursting pressure test by means of self-designed internal-pressure testing machine. Their failure mechanism was dependent on the relationship between heat effect occurred in manufacturing process and internal flaws such as incomplete penetration and pin hole. Also, a finite element analysis was performed to evaluate the stress distribution with respect to the heat and the internal flaws.
Electromagnetic Design Methodology for MR Fluid Actuator
Nam Yun-Joo ; Moon Young-Jin ; Lee Yuk-Hyung ; Park Myeong-Kwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1305~1313
DOI : 10.3795/KSME-A.2006.30.10.1305
This paper presents an electromagnetic design methodology for the magneto-rheological (MR) fluid actuator. In order to improve the performance of the MR fluid actuator, the magnetic circuit including the MR fluid, the ferromagnetic material for flux path and the electromagnetic coil should be well designed, thereby the magnetic field intensity can be effectively supplied to the MR fluid. First of all, in order to improve the static characteristic, the length of the flux path is decreased by removing the unnecessary bulk of the yoke. Next, in order to improve the dynamic and hysteretic characteristics, the magnetic reluctance of the ferromagnetic material is increased by minimizing the cross section through which the flux passes. The effectiveness of the proposed design methodology is verified by the magnetic analysis and a series of basic experiments.
A Novel Fabrication Method of the High-Aspect-Ratio Nano Structure (HAR-Nano Structure) Using a Nano X-Ray Shadow Mask
Kim Jong-Hyun ; Lee Seung-S. ; Kim Yong-Chul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1314~1319
DOI : 10.3795/KSME-A.2006.30.10.1314
This paper describes the novel fabrication method of the high-aspect-ratio nano structure which is impossible by conventional method using a shadow mask and a Deep X-ray Lithography (DXRL). The shadow mask with
apertures is fabricated on the silicon membrane using a conventional UV-lithography. The size of aperture is reduced to 200nm by accumulated low stress silicon nitride using a LPCVD (low pressure chemical vapor deposition) process. The X-ray mask is fabricated by depositing absorber layer (Au,
) on the back side of nano shadow mask. The thickness of an absorber layer must deposit dozens micrometers to obtain contrast more than 100 for a conventional DXRL process. The thickness of
layer can get sufficient contrast using a central beam stop method, blocking high energy X-rays. The nano circle and nano line, 200nm in diameter in width, respectively, were demonstrated 700nm in height with a negative photoresist of SU-8.
Parallel Procedure and Evaluation of Parallel Performance of Impact Simulation Based on Two-Step Eulerian Scheme
Kim Seung-Jo ; Lee Min-Hyung ; Paik Seung-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1320~1327
DOI : 10.3795/KSME-A.2006.30.10.1320
Parallel procedure and performance of two-step Eulerian code have not been reported sufficiently yet even though it was developed and utilized widely in the impact simulation. In this study, parallel strategy of two-step Eulerian code was proposed and described in detail. The performance was evaluated in the self-made linux cluster computer. Compared with commercial code, a relatively good performance is achieved. Through the performance evaluation of each computation stage, remap is turned out to be the most time consuming part among the other part such as FE processing, communication, time marching etc.
Analysis and Measurement of the Nip Pressure of Roll Cleaner
Choi Hyeon-Cheol ; Lee Eung-Ki ; Choi Jong-Guen ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 10, 2006, Pages 1328~1334
DOI : 10.3795/KSME-A.2006.30.10.1328
In the rolling mills for sheet metal rolling, paper rolling and etc., the impurities of roller surface have crucial effects on the surface quality of the products obtained by rolling. The Roll Cleaner is a device to remove impurities on roller surface during a rolling operation. Nip Pressure means the line pressure interacted between the roll cleaner blade and the roller surface. The nip pressure is the most important parameter which decides the performance of roll cleaner, and it depends upon several factors including the cleaner design and its blade stiffness. This study, first, analyzes the mechanism of the nip pressure generation for a roll cleaner designed commercially, which is an crucial process for effective design of roll cleaners. Second, the technique for the measurement of nip pressure is developed, which is useful to verify the performance of roll cleaners and to setup them properly at factory floor.