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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 31, Issue 12 - Dec 2007
Volume 31, Issue 11 - Nov 2007
Volume 31, Issue 10 - Oct 2007
Volume 31, Issue 9 - Sep 2007
Volume 31, Issue 8 - Aug 2007
Volume 31, Issue 7 - Jul 2007
Volume 31, Issue 6 - Jun 2007
Volume 31, Issue 5 - May 2007
Volume 31, Issue 4 - Apr 2007
Volume 31, Issue 3 - Mar 2007
Volume 31, Issue 2 - Feb 2007
Volume 31, Issue 1 - Jan 2007
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An Experimental Study on Brake Judder via the Frequency Analysis of the Brake System and Vehicle System of a Commercial Vehicle
Moon, ll-Dong ; Kim, Jong-Dae ; Oh, Chae-Youn ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 12, 2007, Pages 1131~1138
DOI : 10.3795/KSME-A.2007.31.12.1131
This paper studies experimentally on the building-up process for the amplitude of a commercial truck vibration induced by brake judder. A front axle drum equipped with a drum brake system is utilized for this experiment. A brake dynamo test, a real vehicle ride test and a real vehicle braking test are performed for the analysis of brake judder. The brake dynamo test measures judder by applying brake chamber pressures of 1, 2 and 3 bar at initial brake pad temperatures of
. In order to assess the vertical acceleration at the front axle, the real vehicle ride test on a straight test road with velocities of 20, 40, 60 and 80 km/h is performed. The real vehicle braking test is carried out at the deceleration rate of 0.2g from a velocity of 90km/h for evaluating the vertical, lateral and longitudinal accelerations both at the front axle and at the cab floor under the driver`s seat. The magnitudes and frequencies of the measured peak accelerations from the brake dynamo test, the real vehicle ride test and the real vehicle braking test are comparatively analyzed. This paper shows that the vibration produced by brake judder is built up due to the brake system`s peak acceleration frequency being close to the vehicle ride mode`s frequency.
Development of 3D Micro-Nano Hybrid Patterns Using Anodized Aluminum and Micro-Indentation
Kwon, Jong-Tae ; Shin, Hong-Gue ; Kim, Byeong-Hee ; Seo, Young-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 12, 2007, Pages 1139~1143
DOI : 10.3795/KSME-A.2007.31.12.1139
A simple method for the fabrication of 3D micro-nano hybrid patterns was presented. In conventional fabrication methods of the micro-nano hybrid patterns, micro-patterns were firstly fabricated and then nano-patterns were formatted on the micro-patterns. Moreover, these micro-nano hybrid patterns could be fabricated on the flat substrate. In this paper, we suggested the fabrication method of 3D micro-nano hybrid patterns using micro-indentation on the anodized aluminum substrate. Since diameter of the hemispherical nano-pattern can be controlled by electrolyte and applied voltage in the anodizing process, we can easily fabricated nano-patterns of diameter of loom to 300nm. Nano-patterns were firstly formatted on the aluminum substrate, and then micro-patterns were fabricated by deforming the nano-patterned aluminum substrate. Hemispherical nano-patterns of diameter of 150nm were fabricated by anodizing process, and then micro-pyramid patterns of the side-length of
were formatted on the nano-patterns using micro-indentation. Finally we successfully replicated 3D micro-nano hybrid patterns by hot-embossing process. 3D micro-nano hybrid patterns can be applied to nano-photonic device and nano-biochip application.
Fabrication of Microchannels Having Sub-30 nm Nanofibers Inside of Them via Overlapping Weakly Two-Photon Polymerized Region
Park, Sang-Hu ; Lim, Tae-Woo ; Yang, Dong-Yol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 12, 2007, Pages 1144~1149
DOI : 10.3795/KSME-A.2007.31.12.1144
Experimental studies on the fabrication of sub-30 nm nanofibers using weakly two-photon induced photopolymerized region have been carried out. For the generation of nanofibers inside or outside microstructures, an over-polymerizing method involving a long exposure technique (LET) was proposed. Such nanofibers can find meaningful applications as bio-filters, mixers, and many other uses in diverse research field. A multitude of nanofibers with a notably high resolution (about 22 nm) in two-photon polymerization was achieved using the LET. Furthermore, it was demonstrated that the LET can be employed for the direct fabrication of various embossing patterns by controlling the exposure duration and the interval between yokels. Thin interconnecting networks are formed regularly in the boundary of the over-polymerized region, which allows for the creation of various pattern shapes. Overall of this work, some patterns including nanofibers are fabricated by the LET.
Performances of Multidisciplinary Design Optimization Methodologies in Parallel Computing Environment
Ahn, Moon-Youl ; Lee, Se-J. ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 12, 2007, Pages 1150~1156
DOI : 10.3795/KSME-A.2007.31.12.1150
Multidisciplinary design optimization methodologies play an essential role in modern engineering design which involves many inter-related disciplines. These methodologies usually require very long computing time and design tasks are hard to finish within a specified design cycle time. Parallel processing can be effectively utilized to reduce the computing time. The research on the parallel computing performance of MDO methodologies has been just begun and developing. This study investigates performances of MDF, IDF, SAND and CO among MDO methodologies in view of parallel computing. Finally, the best out of four methodologies is suggested for parallel processing purpose.
Experimental Estimation of Thermal Durability in Ceramic Catalyst Supports for Passenger Car
Baek, Seok-Heum ; Kim, Sung-Yong ; Seung, Sam-Sun ; Yang, Hyup ; Joo, Won-Sik ; Cho, Seok-Swoo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 12, 2007, Pages 1157~1164
DOI : 10.3795/KSME-A.2007.31.12.1157
Ceramic honeycomb structures have performed successfully as catalyst supports for meeting hydrocarbon, carbon monoxide and nitrous emissions standards for gasoline-powered vehicles. Three-way catalyst converter has to withstand high temperature and thermal stress due to pressure fluctuations and vibrations. Thermal stress constitutes a major portion of the total stress which the ceramic catalyst support experiences in service. In this study, temperature distribution was measured at ceramic catalyst supports. Thermal durability was evaluated by power series dynamic fatigue damage model. Radial temperature gradient was higher than axial temperature gradient. Thermal stresses depended on direction of elastic modulus. Axial stresses are higher than tangential stresses. Tangential and axial stresses remained below thermal fatigue threshold in all engine operation ranges.
Nonlinear Response Structural Optimization of a Spacer Grid Spring for a Nuclear Fuel Rod Using the Equivalent Loads
Kim, Do-Won ; Lee, Hyun-Ah ; Song, Ki-Nam ; Kim, Yong-ll ; Park, Gyung-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 12, 2007, Pages 1165~1172
DOI : 10.3795/KSME-A.2007.31.12.1165
The spacer grid set is a part of a nuclear fuel assembly. The set has a spring and the spring supports the fuel rods safely. Although material nonlinearity is involved in the deformation of the spring, nonlinearity has not been considered in design of the spring. Recently a nonlinear response structural optimization method has been developed using equivalent loads. It is called nonlinear response optimization equivalent loads (NROEL). In NROEL, the external loads are transformed to the equivalent loads (EL) for linear static analysis and linear response optimization is carried out based on the EL in a cyclic manner until the convergence criteria are satisfied. EL is the load set which generates the same response field of linear analysis as that of nonlinear analysis. Shape optimization of the spring is carried out based on EL. The objective function is defined by minimizing the maximum stress in the spring while mass is limited and the support force of the spring is larger than a certain value. The results are verified by nonlinear response analysis. ABAQUS is used for nonlinear response analysis and GENESIS is employed for linear response optimization.
Structural Characteristic Analysis of an Ultra-Precision Machine for Machining Large-Surface Micro-Features
Kim, Seok-ll ; Lee, Won-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 12, 2007, Pages 1173~1179
DOI : 10.3795/KSME-A.2007.31.12.1173
In recent years, research to machine large-surface micro-features has become important because of the light guide panel of a large-scale liquid crystal display and the bipolar plate of a high-capacity proton exchange membrane fuel cell. In this study, in order to realize the systematic design technology and performance improvements of an ultra-precision machine for machining the large-surface micro-features, a structural characteristic analysis was performed using its virtual prototype. The prototype consisted of gantry-type frame, hydrostatic feed mechanisms, linear motors, brushless DC servo motor, counterbalance mechanism, and so on. The loop stiffness was estimated from the relative displacement between the tool post and C-axis table, which was caused by a cutting force. Especially, the causes of structural stiffness deterioration were identified through the structural deformation analysis of sub-models.
Lightweight Design of Shell Structures Using Adaptive Inner-Front Level Set Based Topology Optimization (AIFLS-TOP)
Park, Kang-Soo ; Youn, Sung-Kie ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 12, 2007, Pages 1180~1187
DOI : 10.3795/KSME-A.2007.31.12.1180
In the present work, topology optimization method using adaptive inner-front level set method is presented. In the conventional level set based topology optimization method, there exists an incapability for inner-front creation during optimization process. In this regard, as a new attempt to avoid and to overcome the limitation, an inner-front creation algorithm is proposed. In the inner-front creation algorithm, the strain energy density of a structure along with volume constraint is considered. Especially, to facilitate the inner-front creation process during the optimization process, the inner-front creation map which corresponds to the discrete valued function of strain energy density is constructed. In the evolution of the level set function during the optimization process, the least-squares finite element method (LSFEM) is employed. As an application to shell structures, the lightweight design of doubly curved shell and segmented mirror is carried out.
Study on Corrosion Problems in PEMFC Cooling System
Park, Kwang-Jin ; Jeong, Jae-Hwa ; Kim, Jung-Hyun ; Bae, Joong-Myeon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 12, 2007, Pages 1188~1193
DOI : 10.3795/KSME-A.2007.31.12.1188
This study focuses on the corrosion problems of STS316(stainless steel 316) tube for the cooling system of PEMFC (Proton Exchange Membrane Fuel Cell) operation. Deionized water which is highly corrosive is used especially for cooling agent of PEMFC to eliminate electrical conductivity, The tensile stress analysis was performed to check the change of mechanical strength of cooling line and pH of the water was monitored for the observation of extent of corrosion at simulated PEMFC operating condition. When STS316 tube was exposed to deionized water for 500 hours, substantial cracks were found on the surface and the pH of water was decreased from 6.8 to 5.8. For prevention of corrosion problems, the STS316 was coated by three kinds of fluororesin such as PTFE, FEP and ETFE. Among the coating materials, PTFE was the most protective in corrosive environment and was maintained the mechanical strength. To lower the cost, the same experimental analyses were carried out for iron tubes and the result will be discussed in detail.
Fabrication of Copper Micromesh Sheets Using PDMS Flexible Mold
Jung, Sun-Nyeong ; Kang, Chang-Kun ; Jung, Im-Deok ; Bae, Kong-Myeong ; Park, Chi-Yeol ; Jung, Phill-Gu ; Ko, Jong-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 12, 2007, Pages 1194~1199
DOI : 10.3795/KSME-A.2007.31.12.1194
A unique fabrication method for a copper micromesh is proposed and demonstrated. A PDMS mold was fabricated using a microcasting process and then used as a flexible mold in copper electroplating. The fabricated copper micromesh was well formed and connected without any cracks within the entire mold area. The experimental results verified that the fabricated features of the copper micromesh accurately followed the shape of the microstructures of the PDMS mold. This unique fabrication method provides an easy yet precise means of producing three-dimensional metal microstructures.
Hybrid Photoelastic Stress Analysis Around a Central Crack Tip in a Tensile Loaded Plate Using Isochromatic Data
Baek, Tae-Hyun ; Chen, Lei ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 12, 2007, Pages 1200~1207
DOI : 10.3795/KSME-A.2007.31.12.1200
An experimental test is presented for photoelastic stress analysis around a crack tip in tensile loaded plate. The hybrid method coupling photoelastsic fringe inputs calculated by finite element method and complex variable formulations involving conformal mappings and analytical continuity is used to calculate full-field stress around the crack tip in uniaxially loaded, finite width tensile plate. In order to accurately compare calculated fringes with experimental ones, both actual and regenerated photoelastic fringe patterns are two times multiplied and sharpened by digital image processing. Regenerated fringes by hybrid method are quite comparable to actual fringes. The experimental results indicate that Mode I stress intensity factor analyzed by the hybrid method are accurate within three percent compared with ones obtained by empirical equation and finite element analysis.
Development of Pyrolysis Equipment to Depolymerize the Waste Tire
Kim, Tae-Kyu ; Yang, Sang-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 12, 2007, Pages 1208~1213
DOI : 10.3795/KSME-A.2007.31.12.1208
Some structural problems and temperature difference of the pyrolysis equipment were improved by using the structure analysis and the optimal design of torch. The pyrolysis equipment developed in this study is expected to the excellent pyrolysis effect. To modify user-friendly the dimension of a part, we developed the feature modeling system that all of the related parts automatically change applying to the three-dimensional modeling method.
An Experimental Investigation of Bending Fatigue Strength in Table Liner for Cement Mill
Baek, Seok-Heum ; Lee, Kyung-Young ; Cho, Seok-Swoo ; Jang, Deuk-Yul ; Joo, Won-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 12, 2007, Pages 1214~1220
DOI : 10.3795/KSME-A.2007.31.12.1214
The vertical roller mill, which performs the grinding and partly blending of raw material, is the one of the important machine to produce ordinary portland cement. It has been reported that an unexpected fatigue failure occurred in a table liner in the course of grinding portland cement. The life of table liner is estimated to
cycles in the design stage, but at the field, when its operating time reaches to
cycles, the fracture of table liner begins to be found. The fracture of table liner is initiated from the outside edge of grinding path contacting with the grinding roller. Its maintenance normally take 30 % of the total maintenance costs of the roller mill. Therefore, this study shows the clarification of the reasons occurring the fatal destruction of the table liner by fatigue fracture analysis utilizing fracture mechanics and by the finite element method. And, the results from Goodman diagram illustrate relationship of including information on the transition between tensile and bending fatigue strength in the fatigue characterization of table liner.