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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 34, Issue 12 - Dec 2010
Volume 34, Issue 11 - Nov 2010
Volume 34, Issue 10 - Oct 2010
Volume 34, Issue 9 - Sep 2010
Volume 34, Issue 8 - Aug 2010
Volume 34, Issue 7 - Jul 2010
Volume 34, Issue 6 - Jun 2010
Volume 34, Issue 5 - May 2010
Volume 34, Issue 4 - Apr 2010
Volume 34, Issue 3 - Mar 2010
Volume 34, Issue 2 - Feb 2010
Volume 34, Issue 1 - Jan 2010
Selecting the target year
A Study on Thermal Shock of Ceramic Monolithic Substrate
Baek, Seok-Heum ; Park, Jae-Sung ; Kim, Min-Gun ; Cho, Seok-Swoo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 2, 2010, Pages 129~138
DOI : 10.3795/KSME-A.2010.34.2.129
Technical ceramics, due to their unique physical properties, are excellent candidate materials for engineering applications involving extreme thermal and chemical environments. When ceramics are rapidly cooled, they receive thermal shock. The thermal shock parameter is defined as the critical temperature difference. The critical temperature difference for ceramic parts is influenced by its size, the convective heat transfer coefficient, etc. The thermal shock for a component is analyzed by using the transient thermal stress. If the transient thermal stress exceeds the modulus of rupture (MOR), cracking by thermal shock is initiated. The critical temperature difference for water is less than the critical temperature difference for air. The three-way catalyst substrate used in this study has an adequate performance against thermal shock because its radial and axial temperature differences existed below the critical temperature differences.
Analysis of Whiplash by Rear End Collisions Using a Cervical Spine Model with Preloaded Muscles
Oh, Hyun-Woo ; Yang, Seok-Jo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 2, 2010, Pages 139~143
DOI : 10.3795/KSME-A.2010.34.2.139
Whiplash injuries often occur in motor vehicle collision accidents. This injury frequently occurs in the cervical region. However, the reason for this has not yet been clarified. In this study, a multi-body neck model with muscles was designed. Some muscles in the model were preloaded; these were previously determined using the concept of the follower load. Cervical spinal vertebrae, discs, and muscles were designed in accordance with the human cervical spine. The purpose of this study was to investigate the effect of preloads on muscles. The results imply that the whiplash model with preloaded muscles simulates practical situations more closely than models without preloads.
Evaluation of Fatigue Degradation in SUS316L Using Nonlinear Ultrasonics
Choi, Ik-Hwang ; Baek, Seung-Hyun ; Lee, Tae-Hun ; Jhang, Kyung-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 2, 2010, Pages 145~152
DOI : 10.3795/KSME-A.2010.34.2.145
This study evaluated the fatigue degradation in a SUS316L specimen using the nonlinear ultrasonic method. The nonlinearity of the ultrasonic wave was estimated by a relative nonlinear parameter defined as the ratio of the amplitudes for the fundamental wave to the second harmonic wave. In the experiment, a measurement system with contact transducers was constructed; reliable measurements were assured by keeping measurement conditions consistent and reducing extra harmonics generated in the measurement system. Two types of SUS316L specimen were used in experiments; a rotating bar fatigue specimen and a tensile fatigue specimen. The fatigue condition used was high cycle fatigue. The former specimen had a cylindrical shape and was used to observe the change in the nonlinear parameter after fatigue accumulation in a specimen. The latter was a plate-shaped specimen and was used to confirm the change in the nonlinear parameter at the position where the fatigue stress was concentrated. The measured nonlinear parameter showed a strong correlation to the damage level in both fatigue tests.
A Study on the Geometric Design Parameters for Optimization of Cooling Device in the Magnetocardiogram System
Lee, Jung-Hee ; Lee, Young-Shin ; Lee, Yong-Ho ; Lim, Hyun-Kyoon ; Lee, Sung-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 2, 2010, Pages 153~160
DOI : 10.3795/KSME-A.2010.34.2.153
A magnetocardiogram (MCG) is a recording of the biomagnetic signals generated by cardiac electrical activity. Biomagnetic instruments are based on superconducting quantum interference devices (SQUIDs). A liquid cryogenic Dewar flask was used to maintain the superconductors in a superconducting state at a very low temperature (4 K). In this study, the temperature distribution characteristics of the liquid helium in the Dewar flask was investigated. The Dewar flask used in this study has a 30 L liquid helium capacity with a hold time of 5 d. The Dewar flask has two thermal shields rated at 150 and 40 K. The temperatures measured at the end of the thermal shield and calculated from the computer model were compared. This study attempted to minimize the heat transfer rate of the cryogenic Dewar flask using an optimization method about the geometric variable to find the characteristics for the design geometric variables in terms of the stress distribution of the Dewar flask. For thermal and optimization analysis of the structure, the finite element method code ANSYS 10 was used. The computer model used for the cryogenic Dewar flask was useful to predict the temperature distribution for the area less affected by the thermal radiation.
Contact Analysis of a Spherical Particle Between Elastomeric Seal and Steel Surface
Park, Tae-Jo ; Jo, Hyeon-Dong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 2, 2010, Pages 161~166
DOI : 10.3795/KSME-A.2010.34.2.161
Elastomeric seals are widely used in dynamic seal applications, and it is well known that the sealing surfaces can be gradually worn out. Abrasive wear is known to be the most dominant factor; however, little research has been carried out on this problem until now. In this study, a new contact problem related to elastomeric seals-a small spherical particle and steel surface-was modeled and analyzed using MARC. Variations of von-Mises and residual stress distributions as well as deformed seal and steel surface shapes with seal materials and interferences are presented. The stress distribution and surface deformation are highly affected by the elastic properties of seal. For PTFE, the maximum von-Mises stress exceeds the yield strength, and plastic deformation occurs on the steel surface. Therefore, the sealing surface can also be worn down by sub-surface fatigue due to intervening hard particles in the sealing surfaces together with the well-known abrasion.
The Effects of Different Backrest Pivot Positions on the Human Body During Reclining of the Office Chair
Chung, Kyung-Ryul ; Hyeong, Joon-Ho ; Choi, Chun-Ho ; Kim, Sa-Yup ; Hong, Gyu-Seog ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 2, 2010, Pages 167~174
DOI : 10.3795/KSME-A.2010.34.2.167
In this study, the optimal position for the backrest pivot of an office chair was investigated by evaluating its performance in terms of the lumbar support and sliding distance of the back from the backrest during tilting motions. The simulation was performed using a mathematical model, which included a human body and a chair. Forty-two backrest pivot points were selected on the sagittal plane around the hip joint of a sitting model. A motion analysis study was also performed using a prototype of an office chair (A-type) with a backrest pivot located on the hip joint of a normal Korean model and a typical office chair (B-type) with its pivot located under the seat. The simulation results showed that both the lordosis angle and the slide distance of the back were minimized when the backrest pivot was positioned close to the hip joint. The experimental results showed that the slide distance and gap between the sitter's lumbar and the backrest was smaller with the A-type than the B-type. Based on the simulation and experimental results, it can be concluded that the backrest can support the sitter's lumbar area more effectively as the pivot position for reclining approaches closer to the hip joint. In this position, the sitter can maintain a comfortable and healthy sitting posture. This paper presents the methods and guidelines for designing an office chair with ergonomic considerations.
Flexible Multibody Dynamic Analysis of the Wiper System for Automotives
Jung, Sung-Pil ; Park, Tae-Won ; Cheong, Won-Sun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 2, 2010, Pages 175~181
DOI : 10.3795/KSME-A.2010.34.2.175
This paper presents the dynamic analysis method for estimating the performance of flat-type blades in wiper systems. The blade has nonlinear characteristics since the rubber is a hyper-elastic material. Thus, modal coordinate and absolute nodal coordinate formulations were used to describe the dynamic characteristic of the blade. The blade was structurally analyzed to find the bending characteristics of the cross section of the blade. According to the analysis results, the blade section is divided into three deformation bodies: rigid, small, and large. For the small deformation body, the modal coordinate formulation is used, while the absolute nodal coordinate formulation is used for the large deformation body. To verify the dynamic analysis result, an experiment was performed. The simulation and experiment results were compared to verify the flexible multi-body dynamic model.
Evaluation of Position Error and Sensitivity for Ultrasonic Wave and Radio Frequency Based Localization System
Shin, Dong-Hun ; Lee, Yang-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 2, 2010, Pages 183~189
DOI : 10.3795/KSME-A.2010.34.2.183
A localization system for indoor robots is an important technology for robot navigation in a building. Our localization system imports the GPS system and consists of more than 3 satellite beacons and a receiver. Each beacon emits both an ultrasonic wave and radio frequency. The receiver in the robot computes the distance from it to the beacon by measuring the flying time difference between ultrasonic wave and radio frequency. It then computes its position with the distance information from more than 3 beacons whose positions are known. However, the distance information includes errors caused from the ultrasonic sensors; we found it to be limited to within one period of a wave (
tolerance). This paper presents a method for predicting the maximum position error due to distance information errors by using Taylor expansion and singular value decomposition (SVD). The paper also proposes a measuring parameter such as sensitivity to represent the accuracy of the indoor robot localization system in determining the robot's position with regards to the distance error.
Development of a Branch-and-Bound Global Optimization Based on B-spline Approximation
Park, Sang-Kun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 2, 2010, Pages 191~201
DOI : 10.3795/KSME-A.2010.34.2.191
This paper presents a new global optimization algorithm based on the branch-and-bound principle using Bspline approximation techniques. It describes the algorithmic components and details on their implementation. The key components include the subdivision of a design space into mutually disjoint subspaces and the bound calculation of the subspaces, which are all established by a real-valued B-spline volume model. The proposed approach was demonstrated with various test problems to reveal computational performances such as the solution accuracy, number of function evaluations, running time, memory usage, and algorithm convergence. The results showed that the proposed algorithm is complete without using heuristics and has a good possibility for application in large-scale NP-hard optimization.
A Study on Improving the Fatigue Life for a Woven Glass Fabric/Epoxy Laminate Composite Applied to Railway Vehicles
Ko, Hee-Young ; Shin, Kwang-Bok ; Kim, Jung-Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 2, 2010, Pages 203~209
DOI : 10.3795/KSME-A.2010.34.2.203
In this study, the fatigue characteristics and life of a woven glass fabric/epoxy laminate composite applied to railway vehicles was evaluated. The fatigue test was conducted using a tension-tension load with a stress ratio R of 0.1 and frequency of 5 Hz. Two types of woven glass fabric/epoxy laminate composite was used in the fatigue test: with and without carbon/epoxy ply reinforcement. In addition, the fatigue life of the woven glass fabric/epoxy laminate composite was compared with that of aluminum 6005, which is used in the car body and underframe structures of railway vehicles. The test results showed that the failure strength and life of the woven glass fabric/epoxy laminate composite reinforced with three carbon/epoxy plies had a remarkable improvement compared with that of the bare specimen without reinforcement.
Measuring the Tensile Properties of the Nanostructure Using a Force Sensor
Jeon, Sang-Gu ; Jang, Hoon-Sik ; Kwon, Oh-Heon ; Nahm, Seung-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 2, 2010, Pages 211~217
DOI : 10.3795/KSME-A.2010.34.2.211
It is important to measure the mechanical properties of nanostructures because they are required to determine the lifetime and reliability of nanodevices developed for various fields. In this study, tensile tests for a multi-walled carbon nanotube (MWCNT) and a ZnO nanorod were performed in a scanning electron microscope (SEM). The force sensor was a cantilever type and was mounted in front of a nanomanipulator placed in the chamber. The nanomanipulator was controlled using a joystick and personal computer. The nanostructures dispersed on the cut area of a transmission electron microscope (TEM) grid were gripped with the force sensor by exposing an electron beam in the SEM; the tensile tests were the performed. The in situ tensile loads of the nanostructure were obtained. After the tensile test, the cross-sectional areas of the nanostructures were observed by TEM and SEM. Based on the TEM and SEM results, the elastic modulus of the MWCNT and ZnO nanorod were calculated to be 0.98 TPa and 55.85 GPa, respectively.
Development of a Multi-step Stamping Process for the Effective Fabrication of a Thin Sheet for High Aspect Ratio Corrugated Structures
Choi, Sung-Woo ; Park, Sang-Hu ; Jeong, Ho-Seung ; Min, June-Kee ; Jeong, Jae-Hun ; Cho, Jong-Rae ; Kim, Hyun-June ; Willians, Paul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 2, 2010, Pages 219~226
DOI : 10.3795/KSME-A.2010.34.2.219
The stamping process is widely used in fabricating various sheet-parts for vehicle, airplane, and electronic devices due to its low processing cost and high productivity. Recently the use of thin sheets with corrugated structures has rapidly increased for the production of energy devices, e.g., heat exchangers and fuel cells. However, it is very difficult to make corrugated structures directly in the stamping process due to their geometrical complexity. To solve this problem, this paper proposes a multi-step stamping process with a combined heat treatment process: a sequence of the first stamping, heat treatment, and second stamping. By multi-stamping, we obtained successful results in fabricating very thin corrugated structures with thicknesses of
; these are applicable as part of a plate-type heat exchanger.
Design of Bridge Transport System with Equal Incremental Telescopic Motion
Yoon, Kwang-Ho ; Lee, Hyo-Jik ; Lee, Jong-Kwang ; Park, Byung-Suk ; Kim, Ki-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 2, 2010, Pages 227~235
DOI : 10.3795/KSME-AB.2010.34.2.227
This paper introduces the design of a bridge transport system with a telescopic tube for positioning equipment to perform remote handling tasks in a radioactive facility. It consists of an extensible and retractable telescopic tube assembly for z-direction motion, a cabling system for management of power and signal cables, and a trolley system for transverse motion and accommodating servo drives. The working environment for the bridge transport system with the telescopic tube requires strict geometrical constraints, including a short height, short telescopic tube length when retracted, and a long stroke. These constraints were met by solving a nonlinear programming problem involving the optimal dimensions. This paper introduces a cabling system for effective management of cables with changeable lengths to accommodate telescopic motions and a selection guide for servo drives that are sufficient to drive the system.
A Study on the Helical Gear Inspection System for Vehicle Transmission Gear Manufacturing Line
Lee, Min-Ki ; Lee, Eung-Suk ; Kim, Ki-Nam ; Kim, Kwang-Jung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 2, 2010, Pages 237~243
DOI : 10.3795/KSME-A.2010.34.2.237
This paper presents a study on the helical gear inspection system for application to vehicle transmission gear manufacturing lines. The special gear profile inspection system is not suitable for manufacturing lines due to the measuring time. The master gear method, which was used in this study and compared with the machined gear in the line, is more efficient and economical. In this paper, three helical gear inspection parameters were of concern: nick, run-out, and PCD (pitch circle diameter) error. To evaluate its influence on the accuracy, the gear measuring system was also studied. This system can be useful in practical vehicle transmission gear manufacturing lines, where imported equipment is currently being used.
Characterization for Viscoelasticity of Glass Fiber Reinforced Epoxy Composite and Application to Thermal Warpage Analysis in Printed Circuit Board
Song, Woo-Jin ; Ku, Tae-Wan ; Kang, Beom-Soo ; Kim, Jeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 2, 2010, Pages 245~253
DOI : 10.3795/KSME-A.2010.34.2.245
The reliability problems of flip chip packages subjected to temperature change during the packaging process mainly occur due to mismatches in the coefficients of thermal expansion as well as features with time-dependent material properties. Resin molding compounds like glass fiber reinforced epoxy composites used as the dielectric layer in printed circuit boards (PCB) strongly exhibit viscoelastic behavior, which causes their Young's moduli to not only be temperature-dependent but also time-dependent. In this study, the stress relaxation and creep tests were used to characterize the viscoelastic properties of the glass fiber reinforced epoxy composite. Using the viscoelastic properties, finite element analysis (FEA) was employed to simulate thermal loading in the pre-baking process and predict thermal warpage. Furthermore, the effect of viscoelastic features for the major polymeric material on the dielectric layer in the PCB (the glass fiber reinforced epoxy composite) was investigated using FEA.