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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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A Study on the Nonlinearity of Chaotic Signal by Bispectral Analysis
Lee, Hae-Jin ; Lee, Gyeong-Tae ; Park, Young-Sun ; Cha, Kyung-Joon ; Park, Moon-Il ; Oh, Jae-Eung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 8, 2007, Pages 817~825
DOI : 10.3795/KSME-A.2007.31.8.817
During thirty years, deterministic chaos has moved center stage in many areas of applied mathematics. One important stimulus for this, particularly in the early 1970s, was work on nonlinear aspects of the dynamics of plant and animal populations. There are many situations, at least to a crude first approximation, by a simple first-order difference equation. Past studies have shown that such equations, even though simple and deterministic, can exhibit a surprising array of dynamical behavior, from stable points, to a bifurcating hierarchy of stable cycles, to apparently random fluctuations. But higher-order spectral analyses of such behavior are usually not considered. Higher-order spectra of a signal contain important information that is not present in its power spectrum. So, if we find the spectral pattern and get information from it, it will be able to be used effectively in so many fields. Hence, this paper uses auto bicoherence and bicoherence residue which are sort of bispectrum. Applying these to behavior of logistic difference equation, which is typical chaotic signal, the phenomenon of phase coupling and the appearance of frequency band can be analyzed. Such information means that bispectral analysis is useful to detect nonlinearity of signal.
A Splitting Time Integrator for Fully Flexible Cell Molecular Dynamics
Park, Shi-Dong ; Cho, Maeng-Hyo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 8, 2007, Pages 826~832
DOI : 10.3795/KSME-A.2007.31.8.826
Fully flexible cell preserves Hamiltonian in structure so that the symplectic time integrator is applicable to the equations of motion. In the direct formulation of fully flexible cell N-Sigma-T ensemble, a generalized leapfrog time integration (GLF) is applicable for fully flexible cell simulation, but the equations of motion by GLF has structure of implicit algorithm. In this paper, the time integration formula is derived for the fully flexible cell molecular dynamics simulation by using the splitting time integration. It separates flexible cell Hamiltonian into terms corresponding to each of Hamiltonian term. Thus the simple and completely explicit recursion formula was obtained. We compare the performance and the result of present splitting time integration with those of the implicit generalized leapfrog time integration.
Study on Application of Forming Limit Criteria for Formability on Hydroforming Parts
Heo, Seong-Chan ; Song, Woo-Jin ; Ku, Tae-Wan ; Kim, Jeong ; Kang, Beom-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 8, 2007, Pages 833~838
DOI : 10.3795/KSME-A.2007.31.8.833
In tube hydroforming process, several defective products could be obtained such as bursting, wrinkling, folding, buckling. Because, especially, bursting is most frequently occurred failure among the well known failures, it is mostly important to predict the onset of bursting failure on tube hydroforming process. For most sheet metal forming processes, strain based forming limit diagram(FLD) is used often as a criteria to estimate the possibility of onset of the failures proposed above. However, FLD has a shortcoming that it is dependent on strain path while stress based diagram is independent on strain history. Generally, tube hydroforming consists of three main processes such as pre-bending, pre-forming, and hydroforming and it means that the strain histories of final products are nonlinear. Therefore, forming limit stress diagram(FLSD) is more suitable to predict forming limit for hydroforming parts. In this study, FLSD is applied to estimate bursting failure for an engine cradle of an automobile part. Consequently, it is proved that application of FLSD to predict forming limit is available for tube hydroforming parts.
Finite Element Analysis for Prediction of Bead Shape of Nd:YAG Laser Fillet Welding
Kim, Kwan-Woo ; Lee, Jae-Roon ; Suh, Jeong ; Cho, Hae-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 8, 2007, Pages 839~846
DOI : 10.3795/KSME-A.2007.31.8.839
Nd:YAG pulse laser fillet welding of stainless steel plate was simulated to find welding condition by using commercial finite element code MARC. Full model of AISI 304 stainless steel plate was considered and user subroutines were applied to boundary condition for the heat transfer. Material properties such as conductivity, specific heat, mass density and latent heat were given as a function of temperature. As results, Three dimensional heat source model for pulse laser beam conditions of fillet welding has been designed by the comparison between the finite element analysis results and experimental data on AISI 304 stainless steel plate. Nd:YAG laser welding for AISI 304 stainless steel was successfully simulated and it should be useful to determine optimal welding condition.
Shapes and Thermomechanical Analyses of a Hot Roll for Manufacturing Electrodes of Polymer Batteries
Kim, Cheol ; Jang, Dong-Sue ; Yu, Seon-Jun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 8, 2007, Pages 847~854
DOI : 10.3795/KSME-A.2007.31.8.847
The battery electrode of a mobile phone is made of layered polymer coated on aluminum foils and the hot rolling process is applied to increase the density per volume of an electrode for a high capacity battery. The flatness of batteries surfaces should be less than
. To satisfy the required flatness, the deformation of roll surface due to bending and heating of the roll should be minimized. Complicated hot oil paths of
inside the roll are required for heating the polymer layers. FEA was used to calculate thermal deformations and temperatures distributions of the roller. Based on FEA, a modified surface curvature called a crown roll was suggested and this gave the area of 30% improved flatness compared with a flat roll. The flat roll satisfied the flatness of
in the length of 340 mm and the crown roll resulted in the longer length of 460 mm. Experiments to measure the temperature distribution and thermal strain were performed and compared with FEA. There were only 6% difference between two results.
Real-Time Haptic Rendering of Slowly Deformable Bodies Based on Two Dimensional Visual Information for Telemanipulation
Kim, Jung-Sik ; Kim, Young-Jin ; Kim, Jung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 8, 2007, Pages 855~861
DOI : 10.3795/KSME-A.2007.31.8.855
Haptic rendering is a process providing force feedback during interactions between a user and a virtual object. This paper presents a real-time haptic rendering technique for deformable objects based on visual information of intervention between a tool and a real object in a remote place. A user can feel the artificial reaction force through a haptic device in real-time when a slave system exerts manipulation tasks on a deformable object. The models of the deformable object and the manipulator are created from the captured image obtained with a CCD camera and the recognition of objects is achieved using image processing techniques. The force at a rate of 1 kHz for stable haptic interaction is deduced using extrapolation of forces at a low update rate. The rendering algorithm developed was tested and validated on a test platform consisting of a one-dimensional indentation device and an off-the shelf force feedback device. This software system can be used in a cellular manipulation system providing artificial force feedback to enhance a success rate of operations.
Compressive and Torsional Buckling Behavior of Carbon Nanotube Bundles
Jeong, Byeong-Woo ; Lim, Jang-Keun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 8, 2007, Pages 862~869
DOI : 10.3795/KSME-A.2007.31.8.862
The compressive and torsional buckling behavior of carbon nanotube bundles at room temperature is examined with classical molecular dynamics simulation. The critical compressive load and stiffness of a single carbon nanotube in the bundle are found to be similar to those of individual carbon nanotubes. However, the critical torsional moment and stiffness of a single carbon nanotube in the bundle are found to be higher than those of individual carbon nanotubes. In addition, this study demonstrates that van der Waals interactions between the nanotubes in the bundle significantly affect the critical compressive load of the nanotube bundle.
Nondestructive Evaluation of Damage Modes in a Bending Piezoelectric Composite Actuator Based on Waveform and Frequency Analyses
Woo, Sung-Choong ; Goo, Nam-Seo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 8, 2007, Pages 870~879
DOI : 10.3795/KSME-A.2007.31.8.870
In this study, various damage modes in bending unimorph piezoelectric composite actuators with a thin sandwiched PZT plate during bending fracture tests have been evaluated by monitoring acoustic emission (AE) signals in terms of waveform and peak frequency as well as AE parameters. Three kinds of actuator specimens consisting of woven fabric fiber skin layers and a PZT ceramic core layer are loaded with a roller and an AE activity from the specimen is monitored during the entire loading using an AE transducer mounted on the specimen. AE characteristics from a monolithic PZT ceramic with a thickness of
are examined first in order to distinguish different AE signals from various possible damage modes in piezoelectric composite actuators. Post-failure observations and stress analyses in the respective layers of the specimens are conducted to identify particular features in the acoustic emission signal that correspond to specific types of damage modes. As a result, the signal classification based on waveform and peak frequency analyses successfully describes the failure process of the bending piezoelectric composite actuator exhibiting diverse failure mechanisms. Furthermore, it is elucidated that when the PZT ceramic embedded actuators are loaded mechanical bending loads, the failure process of actuator specimens with different lay-up configurations is almost same irrespective of their lay-up configurations.
Load Capability in a Bending Piezoelectric Composite Actuator with a Thin Sandwiched PZT Plate
Woo, Sung-Choong ; Goo, Nam-Seo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 8, 2007, Pages 880~888
DOI : 10.3795/KSME-A.2007.31.8.880
This article describes the load capability of bending piezoelectric actuators with a thin sandwiched PZT plate in association with the stored elastic energy induced by an increased dome height after a curing process. The stored elastic energy within the actuators is obtained via a flexural mechanical bending test. The load capability is evaluated indirectly in terms of an actuating displacement with a load of mass at simply supported and fixed-free boundary conditions. Additionally, a free displacement under no load of mass is measured for a comparison with an actuating displacement. The results reveal that an actuator with a top layer having a high elastic modulus and a low coefficient of thermal expansion exhibits a better performance than the rest of actuators in terms of free displacement as well as actuating displacement due to the formation of the large stored elastic energy within the actuator system. When actuators are excited at AC voltage, the actuating displacement is rather higher than the free displacement for the same actuating conditions. In addition, the effect of PZT ceramic softening results in a slight reduction in the resonance frequency of each actuator as the applied electric field increases. It is thus suggested that the static and dynamic actuating characteristics of bending piezoelectric composite actuators with a thin sandwiched PZT plate should be simultaneously considered in controlling the performance.
Chaos Analysis of Major Joint Motions for Young Males During Walking
Park, Jung-Hong ; Kim, Kwang-Hoon ; Son, Kwon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 8, 2007, Pages 889~895
DOI : 10.3795/KSME-A.2007.31.8.889
Quantifying dynamic stability is important to assessment of falling risk or functional recovery for leg injured people. Human locomotion is complex and known to exhibit nonlinear dynamical behaviors. The purpose of this study is to quantify major joints of the body using chaos analysis during walking. Time series of the chaotic signals show how gait patterns change over time. The gait experiments were carried out for ten young males walking on a motorized treadmill. Joint motions were captured using eight video cameras, and then three dimensional kinematics of the neck and the upper and lower extremities were computed by KWON 3D motion analysis software. The correlation dimension and the largest Lyapunov exponent were calculated from the time series to quantify stabilities of the joints. This study presents a data set of nonlinear dynamic characteristics for eleven joints engaged in normal level walking.
A Study on Bending Behavior of Tunnel Support
Lee, Dong-Woo ; Cho, Seok-Swoo ; Joo, Won-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 8, 2007, Pages 896~902
DOI : 10.3795/KSME-A.2007.31.8.896
The tunnel stability concerned with safety is very important in coal production process. The tunnel supports made by the GI beam has been used in domestic coal mine tunnels, and the GI beam was connected with another by the fish plate. It is necessary to analysis for the bending problems of the fish plate due to the rock pressure in some domestic mine tunnels. Therefore, this study proposes the application possibility of the optimization algorithms for the problem searching a load condition that bring about bending problem in tunnels. Consequently, in order to investigate the load conditions, desirability function as one of the optimization methods to study the bending behavior of tunnel supports was applied.