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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 29, Issue 12 - Dec 2005
Volume 29, Issue 11 - Nov 2005
Volume 29, Issue 10 - Oct 2005
Volume 29, Issue 9 - Sep 2005
Volume 29, Issue 8 - Aug 2005
Volume 29, Issue 7 - Jul 2005
Volume 29, Issue 6 - Jun 2005
Volume 29, Issue 5 - May 2005
Volume 29, Issue 4 - Apr 2005
Volume 29, Issue 3 - Mar 2005
Volume 29, Issue 2 - Feb 2005
Volume 29, Issue 1 - Jan 2005
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Development of an Injection Molded Disposable Chaotic Micromixer: Serpentine Laminating Micromixer (I) - Design and Numerical Analysis -
Kim Dong Sung ; Lee Se Hwan ; Kwon Tai Hun ; Ahn Chong H. ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1289~1297
DOI : 10.3795/KSME-A.2005.29.10.1289
The flow in a microchannel is usually characterized as a low Reynolds number (Re) so that good mixing is quite difficult to be achieved. In this regard, we developed a novel chaotic micromixer, named Serpentine Laminating Micromixer (SLM) in the present study, Part 1. In the SLM, the higher level of chaotic mixing can be achieved by combining two general chaotic mixing mechanisms: splitting/recombination and chaotic advection. The splitting and recombination (in other term, lamination) mechanism is obtained by the successive arrangement of `F`-shape mixing units in two layers. The chaotic advection is induced by the overall three-dimensional serpentine path of the microchannel. Chaotic mixing performance of the SLM was fully characterized numerically. To compare the mixing performance, a T-type micromixer which has the same width, height and length of the SLM was also designed. The three-dimensional numerical mixing simulations show the superiority of the SLM over the T-type micromixer. From the cross-sectional simulation results of mixing patterns, the chaotic advection effect from the serpentine channel path design acts favorably to realize the ideal lamination of fluid flow as Re increases. Chaotic mixing mechanism, proposed in this study, could be easily integrated in Micro-Total-Analysis-System, Lab-on-a-Chip and so on.
Development of an Injection Molded Disposable Chaotic Micromixer: Serpentine Laminating Micromixer (II) - Fabrication and Mixing Experiment -
Kim Dong Sung ; Lee Se Hwan ; Kwon Tai Hun ; Ahn Chong H. ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1298~1306
DOI : 10.3795/KSME-A.2005.29.10.1298
In this paper, Part II, we realized the Serpentine Laminating Micromirer (SLM) which was proposed in the accompanying paper, Part I, by means of the injection molding process in mass production. In the SLM, the higher level of chaotic mixing can be achieved by combining two general chaotic mixing mechanisms of splitting/recombination and chaotic advection by the successive arrangement of `F`-shape mixing units in two layers. Mold inserts for the injection molding process of the SLM were fabricated by SU-8 photolithography and nickel electroplating. The SLM was realized by injection molding of COC (cyclic olefin copolymer) with the fabricated mold inserts and thermal bonding of two injection molded COC substrates. To compare the mixing performance, a T-type micromixer was also fabricated. Mixing performances of micromixers were experimentally characterized in terms of an average mixing color intensity of a pH indicator, phenolphthalein. Experimental results show that the SLM has much better mixing performance than the I-type micromixer and chaotic mixing was successfully achieved from the SLM over the wide range of Reynolds number (Re). The chaotic micromixer, SLM proposed in this study, could be easily integrated in Micro-Total-Analysis- System , Lab-on-a-Chip and so on.
Characteristic Study of Tire Hydroplaning Phenomenon to Vehicle Velocity
Son Jeong-Sam ; Lee Hong-Woo ; Cho Jin-Rae ; Woo Jong-Shik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1307~1314
DOI : 10.3795/KSME-A.2005.29.10.1307
The most important factor of the traffic accident on the wet road is a tire slip caused by hydroplaning. Meanwhile, hydroplaning characteristics are influenced very greatly by the vehicle velocity, so it is very important to reveal the relation between hydroplaning and the vehicle velocity. Since the experiment study is considerably limited, recently the numerical simulation using finite element method(FEM) and finite volume method(FVM) is widely adopted. In this paper, the effect of the vehicle velocity on the hydroplaning characteristics is investigated through the hydroplaning analysis using MSC/Dytran
Effect of Cold Rolling on Fatigue Crack Propagation of TiNi/A16061 Shape Memory Composite
Lee Jin-Kyung ; Park Young-Chul ; Lee Kyu-Chang ; Lee Sang-Pill ; Cho Youn-Ho ; Lee Joon-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1315~1320
DOI : 10.3795/KSME-A.2005.29.10.1315
TiNi alloy fiber was used to recover the original shape of materials using its shape memory effect. The shape memory alloy plays an important role within the metal matrix composite. The shape memory alloy can control the crack propagation in metal matrix composite, and improve the tensile strength of the composite. In this study, TiNi/A16061 shape memory alloy(SMA) composite was fabricated by hot press method, and pressed by a roller for its strength improvement. The four kinds of specimens were fabricated with
and volume fraction of TiNi alloy fiber, respectively. A fatigue test has performed to evaluate the crack initiation and propagation for the TiNi/A16061 SMA composite fabricated by かis method. In order to study the shape memory effect of the TiNi alloy fiber, the test has also done under both conditions of the room temperature and high temperature. The relationship between the crack growth rate and the stress intensity factor was clarified for the composite, and the cold rolling effect was also studied.
Complex Modal Analysis of General Rotor System by Using Floquet Theory
Han Dong-Ju ; Lee Chong-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1321~1328
DOI : 10.3795/KSME-A.2005.29.10.1321
Based upon the Floquet theory, the complex modal solution for general rotor systems with periodically time-varying parameters is newly derived. The complete modal response can be obtained from the orthonormality condition between the time-variant eigenvectors and the corresponding adjoint vectors. The harmonic solutions such as the response and directional special a patterns are then derived in terms of harmonic modes whose coefficients are obtained from the modal analysis. The stability analysis by the Floquet`s transition matrix and the eigen-analysis is also performed.
Axial Collapse Characteristics of Aluminum CFRP Compound Square Members for Vehicle Structural Members
Lee, Kil-Sung ; Cha, Cheon-Seok ; Pyeon, Seok-Beom ; Yang, In-Young ; Sim, Jae-Ki ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1329~1335
DOI : 10.3795/KSME-A.2005.29.10.1329
An aluminum or CFRP (Carbon Fiber ReinfDrced Plastics)is representative one of light-weight materials but its axial collapse mechanism is different from each other. The aluminum member absorbs energy by stable plastic deformation, while the CFRP member absorbs energy by unstable brittle failure with higher specific strength and stiffness than those in the aluminum member. In an attempt to achieve a synergy effect by combining the two members, aluminum CFRP compound square members were manufactured, which are composed of aluminum members wrapped with CFRP outside aluminum square members with different fiber orientation angle and thickness of CFRP, and axial collapse tests were performed fur the members. The axial collapse characteristics of the compound members were analyzed and compared with those of the respective aluminum members and CFRP members. Test results showed that the collapse of the aluminum CFRP compound member complemented unstable brittle failure of the CFRP member due to ductile characteristics of the inner aluminum member. The collapse modes were categorized into four modes under the iuluence of the fiber orientation angle and thickness of CFRP. The absorbed energy Per unit mass, which is in the light-weight aspect was higher in the aluminum CFRP compound member than that in the aluminum member and the CFRP member alone.
Finite Element Analysis for Eddy Current Signal of Aluminum Plate with Surface Breaking Crack
Lee Joon-Hyun ; Lee Bong-Soo ; Lee Min-Rae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1336~1343
DOI : 10.3795/KSME-A.2005.29.10.1336
The detection mechanism of the flaw for the nondestructive testing using eddy current is related to the interaction of the induced eddy currents in the test specimen with flaws and the coupling of these interaction effects with the moving test probe. In this study, the two-dimensional electromagnetic finite element analysis(FEM) fur the eddy current signals of the aluminum plate with different depth of surface cracks is described and the comparison is also made between experimental and predicted signals analyzed by FEM. In addition, the characteristics of attenuation of the eddy current density due to the variation of the depth of a conductor are evaluated. The effective parameters for the application of eddy current technique to evaluate surface cracks are discussed by analyzing the characteristics of the eddy current signals due to the variation of crack depths.
Densifcation Behavior of Iron Powder During Cold Stepped Plastic Deformation
Kang Chunsung ; Lee Sungchul ; Kim KiTae ; Rozenberg Oleg ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1344~1352
DOI : 10.3795/KSME-A.2005.29.10.1344
Densification behavior of iron powder under cold stepped plastic deformation was studied. Experimental data were also obtained for iron powder under cold stepped plastic deformation. The elastoplastic constitutive equation based on yield function of Shima and Oyane was implemented into a finite element program (ABAQUS) to simulate compaction responses of i.on powder during cold stepped plastic deformation. Finite element calculations were compared with experimental data for densification, deformed geometry and density distribution. The agreement between finite element results and experimental data was good for iron powder.
Web-based Draft Verification System for Injection Mold Design
Yeon Kwang-Heum ; Song In-Ho ; Chung Sung-Chong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1353~1360
DOI : 10.3795/KSME-A.2005.29.10.1353
Injection-molded products serve a wide range of applications in our modem lives and their significance is ever increasing. However, difficulty of communication among related companies under the present system results in increase of lead time and decrease of production efficiency. The objective of this paper is the development of a web-based draft verification system in mold design processes. Although several commercial CAD systems offer draft verification functions, those systems are very expensive and inadequate to perform collaborative works. For collaborative work under the distributed environment, the proposed system uses native file transforming of CAD data into optimal format by using the ACIS kernel and InterOp. Functions of draft verification modules are constructed over the ActiveX control using the visual C++ and OpenGL. Therefore, collaborators related to the development of a new product are able to verify the draft and undercut over the Internet without commercial CAD systems. The system helps to reduce production cost, errors and lead-time to the market. Performance of the system is confirmed through various case studies.
Elastic-plastic Fracture Mechanics Analyses for Burst Pressure Prediction of Through-wall Cracked Tubes
Chang Yoon-Suk ; Moon Seong-In ; Kim Young-Jin ; Hwang Seong-Sik ; Kim Joung-Soo ; Kim Yun-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1361~1368
DOI : 10.3795/KSME-A.2005.29.10.1361
The structural and leakage integrity of steam generator tubes should be sustained all postulated loads with appropriate margin even if a crack is present. During the past three decades, for effective integrity evaluation, several limit load solutions have been used world-widely. However, to predict accurately load carrying capacities of specific components under different conditions, the solutions have to be modified by using lots of experimental data. The purpose of this paper is to propose a new burst pressure estimation scheme based on fracture mechanics analyses for steam generator tube with an axial or circumferential through-wall crack. A series of three dimensional elastic-plastic finite element analyses were carried out and, then, closed-form estimation equations with respect to both J-integral and crack opening displacement were derived through reference stress method. The developed engineering equations were utilized for structural integrity evaluation and the resulting data were compared to the corresponding ones fiom experiments as well as limit load solutions. Thereafter, since the effectiveness was proven by promising results, it is believed that the proposed estimation scheme can be used as an efficient tool for integrity evaluation of cracked steam generator tubes.
Global Optimization Using a Sequential Algorithm with Orthogonal Arrays in Discrete Space
Cho Bum-Sang ; Yi Jeong-Wook ; Park Gyung-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1369~1376
DOI : 10.3795/KSME-A.2005.29.10.1369
In structural design, the design variables are frequently selected from certain discrete values. Various optimization algorithms have been developed fDr discrete design. It is well known that many function evaluations are needed in such optimization. Recently, sequential algorithm with orthogonal arrays (SOA), which is a search algorithm for a local minimum in a discrete space, has been developed. It considerably reduces the number of function evaluations. However, it only finds a local minimum and the final solution depends on the initial values of the design variables. A new algorithm is proposed to adopt a genetic algorithm (GA) in SOA. The GA can find a solution in a global sense. The solution from the GA is used as the initial design of SOA. A sequential usage of the GA and SOA is carried out in an iterative manner until the convergence criteria are satisfied. The performance of the algorithm is evaluated by various examples.
Development of an Efficient Method to Consider Weld Distortion in Tolerance Analysis
Yim Hyunjune ; Lee Dongyul ; Lee Jaeyeol ; Kwon Ki Eak ; Shin Jong-Gye ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1377~1383
DOI : 10.3795/KSME-A.2005.29.10.1377
A general and efficient methodology has been developed to analyze dimensional variations of an assembly, taking into account of weld distortion. Weld distortion is generally probabilistic because of the random nature of welding parameters such as the welding speed, maximum welding temperature, ambient temperature, etc. The methodology is illustrated through a very simple example of two perpendicular plates fillet-welded to each other. Two steps comprise the methodology: establishment of a weld-distortion database, and tolerance analysis using the database. To establish the database, thermo-elasto-plastic finite element analyses are conducted to compute the weld distortion for all combinations of discrete values of major welding parameters. In the second step of tolerance analysis, the weld distortion retrieved from the database is used in addition to the dimensional tolerances of the parts. As a result of such an analysis, sensitivities of the assembly`s dimensional variations to the part tolerances and weld distortion are obtained, which can be help improve the dimensional quality of the assembly.
Effect of Metal Removal and Traction Force on Contact Fatigue Life
Seo Jung-Won ; Hur Hun-Mu ; Choi Jae-Boong ; Kim Young-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1384~1391
DOI : 10.3795/KSME-A.2005.29.10.1384
Damage often occurs on the surface of railway wheels due to wheel-rail contact fatigue. It should be removed before reaching wheel failure, because wheel failure can cause derailment with loss of life and property. The increase or decrease of the contact fatigue lift by the metal removal of the contact surface were investigated by many researchers, but they have not considered initial residual stress and traction force. The railway wheel has the initial residual stress formed during the manufacturing process, and the residual stress is changed by thermal stress induced by braking. The traction force and residual stress are operated on wheels of locomotive and electric motor vehicle. In this study, the effect of metal removal depth on the contact fatigue life for a railway wheel has been evaluated by applying lolling contact fatigue test. The effect of the traction force and metal removal on the contact fatigue life has been estimated by finite element analysis. It has been found that the initial residual stress determines the amount of metal removal depth if the traction coefficient is less than 0.15. If the traction coefficient is greater than 0.2, however, the amount of metal removal depth is independent on the intial residual stress.
Risk Assessment of Petrochemical Equipments Using Enhanced RBI Technique
Lee Sang-Min ; Song Ki-Hun ; Chang Yoon-Suk ; Choi Jae-Boong ; Kim Young-Jin ; Han Sang-In ; Choi Song-Chun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1392~1398
DOI : 10.3795/KSME-A.2005.29.10.1392
API 581 guideline provides a methodology for calculating the risks of equipments in refinery or petrochemical plant. However, especially in part of the consequence of failure, there is a major limitation of its application to the petrochemical plant directly since only a representative material is considered in calculating the risk while the equipment is composed of numerous materials. The objectives of this paper are to propose an enhanced risk-based inspection (RBI) technique to resolve shortcomings inclusive of the above issue and to assess the risks of typical petrochemical equipments. In this respect, a program incorporating material database was developed to fully incorporate the characteristics of different materials. The proposed RBI program consists of qualitative, semi-quantitative and quantitative risk evaluation modules in which toxic materials as well as representative materials were selected automatically for comparison to those in the current guideline. It has been applied to assess the risks of equipments in ethylene facilities of petrochemical plants. Thereby, more realistic evaluation results were obtained and applicability of the proposed RBI program was proven.
Development of Assessment Methodology for Locally Wall-Thinned Pipe Under Combined Loading
Shim Do-Jun ; Kim Yun-Jae ; Kim Young-Jin ; Park Chi-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1399~1406
DOI : 10.3795/KSME-A.2005.29.10.1399
Recently authors have proposed a new method to estimate failure strength of a pipe with local wall thinning subject to either internal pressure or global bending. The proposed method was based on the equivalent stress averaged over the minimum ligament in the locally wall thinned region, and the simple scheme to estimate the equivalent stress in the minimum ligament was proposed, based on the reference stress concept. This paper extends the new method to combined internal pressure and global bending. The proposed method is validated against FE results for various geometries of local wall thinning under combined loading. The effect of internal pressure is also investigated in the present study. Comparison of maximum moments, predicted according to the proposed method, with published full-scale pipe test data fur locally wall-thinned pipes under combined internal pressure and global bending, shows good agreement.
Strength Change due to Plastic Deformation in Al 2024 Ultrafine Grained ECAP Metal
Choi, Jeong-Woo ; Ma, Young-Wha ; Yoon, Kee-Bong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1407~1415
DOI : 10.3795/KSME-A.2005.29.10.1407
Strength change of an over-aged A12024 material was studied after being subjected to stages of severe plastic deformation by ECAP (Equal Channel Angular Pressing). Various kinds of strength value were measured using the conventional tensile test, Rockwell and Vickers hardness and the SP (small punch) test Due to limitation of the specimen size, tension test in transverse direction could not be conducted. Hence, SP test was employed for assessing the strength in transverse direction. Based on TEM observation the measured strength characteristics were explained based on the relation between microstructure, dislocation and strength. As the number of ECAP pass increases, the strength of A12024 was also increased. However, considerable change of strength, which is generally predicted, was not observed in this study. For the strength in transverse direction even decrease of the strength was observed after 6 passes of ECAP. It was argued that this decrease was due to dynamic recovery of dislocation density during or after ECAP processes at
. The strength assessment equation proposed by the authors in the previous paper was shown to be very accurate. This argument was supported by comparing the results of conventional tensile test with those of SP test. It was also pointed that the Rockwell har(3ness value seemed to be able to represent the strength in the transverse direction.
A Study on Performance Improvement of Whirling Machines
Lee Jung-Ki ; Yang Woo-suk ; Son Jea-seok ; Han Hui-duck ; Kim Han-soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1416~1429
DOI : 10.3795/KSME-A.2005.29.10.1416
In order to meet the increasing competitive pressures coupled with higher demands for component quality, whirling machines have been at the cutting edge of the automobile industry for more than 25 years. The hard whirling process can save on machining time and operation elimination. Hard whirling is done dry, without coolant. The chips carry away nearly all of the heat during cutting, leaving the workpiece cool and minimizing any thermal geometry variations. The surface finish and profile accuracy are close to grinding quality. Whirling machines usually consist of four major parts; 1) loading system that requires the necessary axial speeds, 2) head stock that needs high precision clamping and positioning system at the chuck and tailstock, 3) whirling unit that demands the high cutting speeds and cutting power fer cutting deep thread profiles and 4) unloading system that requires an easy workpiece unloading. Also, capabilities of the whirling machine can be improved by attaching a vision system to the machine. Most of whirling machines in Korean automobile industry are imported from the Leistritz company, Germany and the Hasegawa company, Japan. Tn this paper, a basic research will be performed to improve and enhance the existing whirling machines. Finally, a new Korean whirling machine will be proposed and developed.
A Study on Method for Improving Reproducibility in the Ultrasonic Measurement of Bone Mineral Density
Shin, Jeong-Sik ; Ahn, Jung-Hwan ; Kim, Hwa-Young ; Kim, Hyung-Jun ; Han, Seung-Moo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 10, 2005, Pages 1430~1437
DOI : 10.3795/KSME-A.2005.29.10.1430
It is very important to achieve a high reproducibility in the ultrasonic measurement of bone mineral density. In this study, we examined number of sampling waveform, control of temperature, diameter of region of interest as factors to improve reproducibility. We decided the optimal number of waveforms to be converted to frequency domain as period of 1. We have minimized the effects of variable temperature and constrained generation of micro bubble by keeping temperature within a range of
with a precise temperature controlling algorithm. We also found the optimal diameter of region of interest to be 13mm. In this paper, we demonstrated the improved reproducibility by controlling various factors affecting the ultrasonic measurement of bone mineral density.