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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 35, Issue 12 - Dec 2011
Volume 35, Issue 11 - Nov 2011
Volume 35, Issue 10 - Oct 2011
Volume 35, Issue 9 - Sep 2011
Volume 35, Issue 8 - Aug 2011
Volume 35, Issue 7 - Jul 2011
Volume 35, Issue 6 - Jun 2011
Volume 35, Issue 5 - May 2011
Volume 35, Issue 4 - Apr 2011
Volume 35, Issue 3 - Mar 2011
Volume 35, Issue 2 - Feb 2011
Volume 35, Issue 1 - Jan 2011
Selecting the target year
Internet-Based Real-Time Collaborative Design System
Cha, Joo-Heon ; Lee, Sun-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 701~707
DOI : 10.3795/KSME-A.2011.35.7.701
The aim of this paper is to develop a collaborative design system that can facilitate remote modification and control of a 3D solid model through the Internet. It enables the users to resolve conflicting viewpoints about an issue and collaborate to design a tangible object within a given set of constraints. In order to optimize the collaborative design system, we focus on the results obtained by using the collaborative design method for the real-time modification of a 3D solid model in a distributed environment. It also provides the method of managing the consistency between design entities. The efficiency of the system is verified by implementing it in a distributed environment.
A Switching Notch Filter for Reducing the Torque Ripple Caused by a Harmonic Drive in a Joint Torque Sensor
Kim, Joon-Hong ; Kim, Young-Loul ; Song, Jae-Bok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 709~715
DOI : 10.3795/KSME-A.2011.35.7.709
Harmonic drives have been widely used in combination with joint torque sensors in order to facilitate accurate manipulator control. A harmonic drive causes a torque ripple because of its structural characteristics, and this torque ripple tends to deteriorate the performance of a controller or observer that uses torque sensors. This paper proposes a switching notch filter for reducing the torque ripple caused by a harmonic drive in a joint torque sensor; the functioning of this filter is based on the relationship between the frequency components of the torque ripple and the rotational velocity of the harmonic drive. The proposed switching notch filter is advantageous in that it requires less computational load and does not necessitate additional circuits or structures. Various experiments demonstrate that the proposed filter has good filtering performance, fast response, and good switching stability.
FE-Simulation and Measurement of the Residual Stress in Al6061 During T6 Heat Treatment
Ko, Dae-Hoon ; Kim, Tae-Jung ; Lim, Hak-Jin ; Lee, Jung-Min ; Kim, Byung-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 717~722
DOI : 10.3795/KSME-A.2011.35.7.717
The purpose of this study is to predict the residual stress in Al6061 during T6 heat treatment. In this study, the variable residual stress in case of the solid solution(
, 2h) and artificial ageing(
, 9h) of Al6061 subjected to T6 heat treatment is determined at different ageing times. A heat treatment experiment is conducted to determine the heat transfer coefficient, on the basis of which the residual stress during the T6 heat treatment is predicted. In order to take into account the relaxation of residual stress during artificial ageing, a Zener-Wert-Avrami function is used and elasto-plastic nonlinear analysis is conducted through FE-simulation. Further, the residual stress is measured by using the X-ray diffraction(XRD) method, and the result is compared with the result from the FE-simulation. It is found that the residual stress predicted form the FE-simulation is in good agreement with the residual stress measured by using the XRD method.
Optimization of the Cam Profile of a Vacuum Circuit Breaker by Using Multibody Dynamics Techniques
Jang, Jin-Seok ; Sohn, Jeong-Hyun ; Yoo, Wan-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 723~728
DOI : 10.3795/KSME-A.2011.35.7.723
Since the performance of a vacuum circuit breaker (VCB) mainly depends on the spring operating mechanism, an analysis of the spring operating mechanism is required in order to improve the design of a VCB. In this study, the static stiffness of the spring was determined by using a material testing machine, and the test results were used to model the spring through computer simulation. The multi-body dynamic model of the spring was established by using the RecurDyn program. The dynamic model was verified by comparing the results of stem displacements and rotating angles of the brake shaft obtained from the simulation and from the experiments. After verification of the dynamic model of VCB, the cam profile of the VCB was optimized through multi-body dynamics simulation in order to improve the performance of the closing mechanism.
TOPSIS-Based Multi-Objective Shape Optimization for a CRT Funnel
Lee, Kwang-Ki ; Han, Jeong-Woo ; Han, Seung-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 729~736
DOI : 10.3795/KSME-A.2011.35.7.729
The technique for order preference by similarity to ideal solution (TOPSIS) is regarded as a classical method of multiple attribute decision making (MADM), often used to solve various decision-making or selection problems. It is based on the concept that the chosen alternative should have the shortest distance from the positive ideal solution and the farthest distance from the negative ideal solution. The TOPSIS can be applied to a design process for carrying out multi-objective shape optimization wherein the best and worst alternatives are to be decided. In this paper, multi-objective shape optimization using the TOPSIS and Rational Bezier curve was applied to the funnel of a cathode-ray tube (CRT). In order to minimize the weight and first principal stress, a new multi-objective shape optimization methodology is proposed, wherein the relative-closeness coefficients of the TOPSIS are defined as the performance indices of a multi-objective function and evaluated by response surface models. This methodology enables the designer to decide on the best solution from a number of design specification groups by examining the various conflicts between the weight and the first principal stress.
Audio-Visual Fusion for Sound Source Localization and Improved Attention
Lee, Byoung-Gi ; Choi, Jong-Suk ; Yoon, Sang-Suk ; Choi, Mun-Taek ; Kim, Mun-Sang ; Kim, Dai-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 737~743
DOI : 10.3795/KSME-A.2011.35.7.737
Service robots are equipped with various sensors such as vision camera, sonar sensor, laser scanner, and microphones. Although these sensors have their own functions, some of them can be made to work together and perform more complicated functions. AudioFvisual fusion is a typical and powerful combination of audio and video sensors, because audio information is complementary to visual information and vice versa. Human beings also mainly depend on visual and auditory information in their daily life. In this paper, we conduct two studies using audioFvision fusion: one is on enhancing the performance of sound localization, and the other is on improving robot attention through sound localization and face detection.
Modeling of Size-Dependent Strengthening in Particle-Reinforced Aluminum Composites with Strain Gradient Plasticity
Suh, Yeong-Sung ; Park, Moon-Shik ; Song, Seung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 745~751
DOI : 10.3795/KSME-A.2011.35.7.745
This study proposes finite element modeling of dislocation punching at cooling after consolidation in order to calculate the strength of particle-reinforced aluminum composites. The Taylor dislocation model combined with strain gradient plasticity around the reinforced particle is adopted to take into account the size-dependency of different volume fractions of the particle. The strain gradients were obtained from the equivalent plastic strain calculated during the cooling of the spherical unit cell, when the dislocation punching due to CTE (Coefficient of Thermal Expansion) mismatch is activated. The enhanced yield stress was observed by including the strain gradients, in an average sense, over the punched zone. The tensile strength of the SiCp/Al 356-T6 composite was predicted through the finite element analysis of an axisymmetric unit cell for various sizes and volume fractions of the particle. The predicted strengths were found to be in good agreement with the experimental data. Further, the particle-size dependency was clearly established.
Low-Cycle Fatigue Life Prediction in GTD-111 Superalloy at Elevated Temperatures
Yang, Ho-Young ; Kim, Jae-Hoon ; Yoo, Keun-Bong ; Lee, Han-Sang ; You, Young-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 753~758
DOI : 10.3795/KSME-A.2011.35.7.753
The Ni-base super-heat-resistant alloy, GTD-111, is employed in gas turbines because of its high temperature strength and oxidation resistance. It is important to predict the fatigue life of this superalloy in order to improve the efficiency of gas turbines. In this study, low-cycle fatigue tests are performed as variables of total strain range and temperature. The relationship between the strain energy density and number of cycles to failure is examined in order to predict the low-cycle fatigue life of the GTD-111 superalloy. The fatigue life predicted by using the strain-energy methods is found to coincide with that obtained from the experimental data and from the Coffin-Manson method.
Design Optimization of an Accumulator for Noise Reduction of Rotary Compressor
Lee, Ui-Yoon ; Kim, Bong-Joon ; Lee, Jeong-Bae ; Sung, Chun-Mo ; Lee, Un-Seop ; Lee, Jong-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 759~766
DOI : 10.3795/KSME-A.2011.35.7.759
Recently, noise reduction in room air conditioners has been one of the important issues as well as cooling efficiency. The rotary compressor is the dominant noise source in an air conditioner. A number of studies have been conducted on reducing compressor noise through improving muffler and resonator design. However the noise from the accumulator, a noise delivering path between compressor and air conditioner, is not fully taken into consideration. The accumulator contains a large inner cavity, and usually generates additional resonance noise during operation. This paper aims to conduct an optimal design for reducing accumulator noise by maximizing the transmission loss within the target frequency range that represents high-order nonlinearity. Design of experiments and radial basis function neural network are used in the context of approximate meta-models, and genetic algorithm is used as an optimization tool.
Trajectory Generation for a Biped Robot Using ELIPM
Park, Goun-Woo ; Choi, See-Myoung ; Park, Jong-Hyeon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 767~772
DOI : 10.3795/KSME-A.2011.35.7.767
Trajectory generation is important because it determines the walking stability, continuity, and performance of a body in motion. Generally, the Linear Inverted Pendulum Mode is used for trajectory generation; however, for the sake of simplicity, the trajectory in this mode does not allow vertical motions and pitching motions of the body. This paper proposes a new trajectory generation method called Extended Linear Inverted Pendulum Mode (ELIPM) that allows vertical motion as well as pitching motion. This method can also improve the performance of locomotion by controlling the stride and locomotion frequency of a body.
An Experimental Study on the Material Characteristics of Mechanical Filters for Eliminating High-Frequency Noise in Accelerometer Measurements
Choi, Won-Yeong ; Yoo, Seong-Yeol ; Cha, Ki-Up ; Kim, Sung-Soo ; Noh, Myoung-Gyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 773~778
DOI : 10.3795/KSME-A.2011.35.7.773
Accelerometers are widely used to measure the lateral vibrations of pipe-like structures such as a gun tube under impulse loads. Stress waves that precede the lateral vibrations due to the explosion within a gun contribute little to the vibrations, but saturate the accelerometer input. A mechanical filter eliminates this high-frequency stress wave and only transmits the signal corresponding to the lateral vibrations. The mechanical filter consists of a mechanical structure for mounting the accelerometers and a damping material. The low-pass filter characteristics are determined from the equivalent damping and stiffness property of this damping material. In this paper, we tested nine commercially available damping materials for their vibration characteristics by using a test rig. We also observed the change in the vibration characteristics while compressing the material. We designed and manufactured a mechanical filter and verified its filtering performance.
Bending Strength Properties of SiC Ceramics at Different Roughness Values of Polishing Plates
Nam, Ki-Woo ; Kim, Eun-Sun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 779~784
DOI : 10.3795/KSME-A.2011.35.7.779
This study was carried out on the crack healing of three types of SiC ceramics based on a
additive, taking into account the roughness of the polishing plate used for polishing the specimens. The mixtures were subsequently hot-pressed in
gas for one hour under 35 MPa at 2053 K. In these specimens, the optimized crack-healing condition was 1373 K for one hour in air. The crack-healing material of the cracked part was the glassy phase of
that was formed by the oxidation of SiC. In the optimum healing condition, the bending strength of non-polished SiC ceramics was not completely recovered. However, the bending strength of the SAY specimen was excellent, considering the economic aspects of SAY, SAYS-1, and SAYS-2. The SAY specimen is definitely superior to the others after an hour of heat treatment. There was a decrease in the number and size of defects in the specimen polished by using a
polishing plate; however, the micro-surface defects were not completely repaired. The specimen polished by using a 40-
polishing plate showed little voids or surface defects after an hour of heat treatment. The bending strength of the specimen mirror-polished by using a 6-
polishing plate was completely recovered.
Analysis of the Uncertainty of Compressive Forces Acting on the Patella by Using Multi-Body Modeling and Muscle Mechanics
NamGoong, Hong ; Yoo, Hong-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 785~790
DOI : 10.3795/KSME-A.2011.35.7.785
The goal of this study is to estimate the force acting on the knee joint in the human body by using the Hilltype muscle model based on a musculoskeletal model of the human lower extremity in the sagittal plane. For estimating the force applied, the human leg is modeled using multi-body modeling. This leg model comprises biarticular muscles acting on two joints of the upper and lower limbs, and the muscles include some of the major muscles such as the hamstring. In order to analyze the uncertainty of the applied forces acting on the knee joint, statistical distributions of human body, leg part, parameters are required and to obtain the parameter's statistical characteristic of the part sample survey method is employed. Finally, by using the sensitivity information of the parameters, the force acting on the knee joint can be estimated.
Prediction of the Performance Distributions and Manufacturing Yields of a MEMS Accelerometer
Kim, Yong-Il ; Yoo, Hong-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 791~798
DOI : 10.3795/KSME-A.2011.35.7.791
All mechanical-system parameters have uncertainty, and this uncertainty directly affects system performances and results in a decrease in the manufacturing outputs. In particular, since the size of a MEMS system is extremely small, the manufacturing tolerances of a MEMS system are relatively large when compared to the tolerances of a macro-scale system. High manufacturing tolerances result from an increase in the uncertainty of the system parameters, thereby affecting the performances and manufacturing yields. In this paper, the performance uncertainty of a MEMS accelerometer due to system parameter uncertainty is analyzed by using several uncertainty analysis methods. Finally, the performance distributions and manufacturing yields of the MEMS accelerometer are predicted.
Study on the Failure Mechanism of a Chip Resistor Solder Joint During Thermal Cycling for Prognostics and Health Monitoring
Han, Chang-Woon ; Park, Noh-Chang ; Hong, Won-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 799~804
DOI : 10.3795/KSME-A.2011.35.7.799
A thermal cycling test was conducted on a chip resistor solder joint with real-time failure monitoring. In order to study the failure mechanism of the chip resistor solder joint during the test, the resistance between both ends of the resistor was monitored until the occurrence of failure. It was observed that the monitored resistance first fluctuated linearly according to the temperature change. The initial variation in the resistance occurred at the time during the cycle when there was a decrease in temperature. A more significant change in the resistance followed after a certain number of cycles, during the time when there was an increase in the temperature. In order to explain the failure patterns of the solder joint, a mechanism for the solder failure was suggested, and its validity was proved through FE simulations. Based on the explained failure mechanism, it was shown that prognostics for the solder failure can be implemented by monitoring the resistance change in a thermal cycle condition.
Maximization of the Output Voltage of a Cantilevered Energy Harvester Comprising Piezoelectric Fiber Composites
Kim, Seon-Myeong ; Kim, Cheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 805~812
DOI : 10.3795/KSME-A.2011.35.7.805
In this study, a cantilevered energy harvester comprising piezoelectric fiber and epoxy composites was designed and analyzed electro-mechanically. In order to maximize the power of the cantilevered energy harvester, its exciting frequency was tuned to the first natural frequency of the beam. An efficient analysis method for predicting the output voltage of the beam was developed by using the finite element method coupled with piezoelectric behavior. By using this method, the effects of geometric parameters and various piezoelectric materials on power generation were investigated and the electric characteristics were evaluated. Design optimization of the beam geometries was performed for a base model. The optimum MFC design generated a maximum electric output of 40.1 V at a first natural frequency of 24.5 Hz.
Study of the Characteristics of Hydrogen-Gas Filling Process of Ultra-Light Composite Tanks for Fuel-Cell Vehicles
Yoo, Gye-Hyoung ; Kim, Jong-Lyul ; Lee, Taek-Su ; Lee, Joong-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 813~819
DOI : 10.3795/KSME-A.2011.35.7.813
In this research, we investigated the hydrogen-gas filling characteristics of ultra-light composite tanks that have a plastic or aluminum liner inside the composite shell. The study was performed for different gas and tank temperatures. The temperature changes at various positions in the Type-4 tank during hydrogen-gas filling were monitored in order to understand the effects of the filling conditions. The results were compared with those obtained for a Type-3 tank. As the filling speed was increased, a quicker temperature rise was observed, and the temperature distribution over the entire region showed significant discrepancies.
Lightweight Crane Design by Using Topology and Shape Optimization
Kim, Young-Chul ; Hong, Jung-Kie ; Jang, Gang-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 821~826
DOI : 10.3795/KSME-A.2011.35.7.821
CAE-based structural optimization techniques are applied for the design of a lightweight crane. The boom of the crane is designed by shape optimization with the shape of the cross section of the boom as the design variable. The design objective is mass minimization, and the static strength and dynamic stiffness of the system are set as the design constraints. Hyperworks, a commercial analysis and optimization software, is used for shape and topology optimization. In order to consistently change the shape of the elements of the boom with respect to the change in the shape of its cross section, the morphing function in Hyperworks is used. The support of the boom of the original model is simplified to model the design domain for topology optimization, which is discretized by using three-dimensional solid elements. The final result after shape and topology optimization is 19% and 17% reduction in the masses of the boom and support, respectively, without a deterioration in the system stiffness.
Analysis of the Current-Collection Performance of a High-Speed Train Using Finite Element Analysis Method
Jung, Sung-Pil ; Park, Tae-Won ; Kim, Young-Guk ; Park, Chan-Kyoung ; Paik, Jin-Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 7, 2011, Pages 827~833
DOI : 10.3795/KSME-A.2011.35.7.827
In this study, a simulation model to estimate the current-collection performance of a high-speed train was developed by using a commercial finite element analysis software, SAMCEF. A three-dimensional springDdamperDmass model of a pantograph was created, and its reliability was validated by comparing the receptance of the model to that of the actual pantograph. The wave propagation speed of the catenary model was compared with the analytical wave propagation speed of the catenary system presented in the UIC 799 OR standard. The length of the droppers was controlled, and the pre-sag of the contact wire due to gravity was considered. The catenary and the pantograph were connected by using a contact element, and the contact force variation when the pantograph was moved at velocities of 300 km/h and 370 km/h was obtained. The average, standard deviation, maximum, and minimum values of the contact force were analyzed, and the effectiveness of the developed simulation model was examined.