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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 33, Issue 12 - Dec 2009
Volume 33, Issue 11 - Nov 2009
Volume 33, Issue 10 - Oct 2009
Volume 33, Issue 9 - Sep 2009
Volume 33, Issue 8 - Aug 2009
Volume 33, Issue 7 - Jul 2009
Volume 33, Issue 6 - Jun 2009
Volume 33, Issue 5 - May 2009
Volume 33, Issue 4 - Apr 2009
Volume 33, Issue 3 - Mar 2009
Volume 33, Issue 2 - Feb 2009
Volume 33, Issue 1 - Jan 2009
Selecting the target year
Estimation of Probability Distribution Fit for Fatigue Crack Propagation Life of AZ31 Magnesium Alloy
Choi, Seon-Soon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 707~719
DOI : 10.3795/KSME-A.2009.33.8.707
The variables relating to the fatigue behavior have uncertainty and are random. The fatigue crack propagation is, thus, stochastic in nature. In this study, fatigue experiments are performed on the specimen of the magnesium alloy AZ31. The data of the fatigue life are scattered even in the same experimental condition. It is necessary to determine the probability distribution of the fatigue crack propagation life for the reliability analysis as well as the design and maintenance of structural components. Therefore the statistics and the probability distribution for the fatigue crack propagation life are investigated and the best fit probability distribution of that is proposed in this paper.
Design Optimization Considering Optical Performances for LCD/BLU Using PIDO
Lee, Gab-Seong ; Park, Seon-Ho ; Yoon, Sang-Joon ; Choi, Dong-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 720~725
DOI : 10.3795/KSME-A.2009.33.8.720
Among many kinds of parts for Liquid Crystal Display (LCD), a Back Light Unit (BLU) that changes the path of the light from light source to screen is the most important part to improve optical performances such as uniformity and average value of brightness. Up to recently, design process of BLU has been carried out by depending on the experience of design engineer. Using this approach, however, is proven that it is hard to effectively deal with difficulties in a process of the LCD development such as frequent design modifications, various design requirements, and short-term development. To cope with this situation, we applied a Process Integration and Design Optimization (PIDO) based design environment. PIDO is a software package to integrate multiple simulation processes and find a better solution using various design techniques. In this research, we found a design solution satisfying all design requirements by using the PIDO.
Multi-Objective Geometric Optimal Design of a Linear Induction Motor Using Design of Experiments and the Sequential Response Surface Method
Ryu, Tae-Hyung ; Yoo, Jeong-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 726~732
DOI : 10.3795/KSME-A.2009.33.8.726
In many industries, the linear motor replaces the existing framework for linear transportation. Similar to other conventional motors, it is important to minimize the ripple of thrust and to maximize the thrust force of the linear motor. Because the two objectives are associated to each other, the multi-objective design process is necessary considering all objectives. This paper intends to optimize geometric parameters of the linear motor with two design objectives using design of experiments and sequential response surface method.
Comparative Study of the Nanomechanics of Si Nanowires
Lee, Byeong-Chan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 733~738
DOI : 10.3795/KSME-A.2009.33.8.733
Mechanical properties of <001> silicon nanowires are presented. In particular, predictions from the calculations based on different length scales, first principles calculations, atomistic calculations, and continuum nanomechanical theory, are compared for <001> silicon nanowires. There are several elements that determine the mechanics of silicon nanowires, and the complicated balance between these elements is studied. Specifically, the role of the increasing surface effects and reduced dimensionality predicted from theories of different length scales are compared. As a prototype, a Tersoff-based empirical potential has been used to study the mechanical properties of silicon nanowires including the Young's modulus. The results significantly deviates from the first principles predictions as the size of wire is decreased.
Lifetime Prediction of Rubber Pad for High Speed Railway Vehicle
Woo, Chang-Su ; Choe, Byeong-Ik ; Park, Hyun-Sung ; Yang, Shin-Chu ; Jang, Sung-Yep ; Kim, Eun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 739~744
DOI : 10.3795/KSME-A.2009.33.8.739
Rail-pad is an important and readily replaceable component of a railway track, as it is the elastic layer between the rail and the sleeper. Characteristics and useful lifetime prediction of rail-pad was very important in design procedure to assure the safety and reliability. In this paper, the degradation of rail pad properties as a function of their in-service life is studied with a view of developing a technique for predicting the optimum period of track maintenance with regard to pad replacement. In order to investigate the useful lifetime, the accelerate test were carried out. Accelerated test results changes as the threshold are used for assessment of the useful life and time to threshold value were plotted against reciprocal of absolute temperature to give the Arrhenius plot. By using the acceleration test, several useful lifetime prediction for rail-pads were proposed.
Robust Structural Optimization Using Gauss-type Quadrature Formula
Lee, Sang-Hoon ; Seo, Ki-Seog ; Chen, Shikui ; Chen, Wei ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 745~752
DOI : 10.3795/KSME-A.2009.33.8.745
In robust design, the mean and variance of design performance are frequently used to measure the design performance and its robustness under uncertainties. In this paper, we present the Gauss-type quadrature formula as a rigorous method for mean and variance estimation involving arbitrary input distributions and further extend its use to robust design optimization. One dimensional Gauss-type quadrature formula are constructed from the input probability distributions and utilized in the construction of multidimensional quadrature formula such as the tensor product quadrature (TPQ) formula and the univariate dimension reduction (UDR) method. To improve the efficiency of using it for robust design optimization, a semi-analytic design sensitivity analysis with respect to the statistical moments is proposed. The proposed approach is applied to a simple bench mark problems and robust topology optimization of structures considering various types of uncertainty.
Global Function Approximations Using Wavelet Neural Networks
Shin, Kwang-Ho ; Lee, Jong-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 753~759
DOI : 10.3795/KSME-A.2009.33.8.753
Feed-forward neural networks have been widely used as function approximation tools in the context of global approximate optimization. In the present study, a wavelet neural network (WNN) which is based on wavelet transform theory is suggested as an alternative to a traditional back-propagation neural network (BPN). The basic theory of wavelet neural network is briefly described, and approximation performance is tested using a nonlinear multimodal function and a composite rotor blade analysis problem. Laplacian of Gaussian function, Mexican function, and Morlet function are considered during the construction of WNN architectures. In addition, approximation results from WNN are compared with those from BPN.
Baseplate Design to Improve Swaging Performance of Actuator in a HDD
Lee, Haeng-Soo ; Hong, Eo-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 760~766
DOI : 10.3795/KSME-A.2009.33.8.760
In the manufacturing process of HDD, ball swaging method is commonly used to joint the Head Gimbal Assembly(HGA) with the arm of the actuator. The hub on the HGA is placed into the hole of the actuator arm, and the hub and arm is bonded by the pressure of steel ball. The pressure for plastic deformation on the baseplate causes the undesirable deformation on HGA, such as tilting, flying height change of head. After obtaining the key parameters that have large sensitivity on the swaging process, the optimal shape of baseplate is proposed to increase the static performance during swaging process. Contribution of the proposed design for the swaging performance is verified by contact simulation with elasto-plastic deformation.
Residual Stress Prediction in LSP Surface Treatment by Using FEM
Bang, Boo-Woon ; Son, Seung-Kil ; Kim, Jae-Min ; Cho, Chong-Du ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 767~772
DOI : 10.3795/KSME-A.2009.33.8.767
Laser shock peening(LSP) is proving to be better surface treatment than conventional one such as shot peening. The LSP process has a compressive residual stress into a metal alloy and a significant improvement in fatigue life. Our research is focused on applying finite element method to the prediction of residual stress through the LSP processing in some LSP conditions such as pressure and spot size induced by laser. Two analysis methods are considered to calculating the compressive residual stress. But the explicit solution and the static one after partially explicit solving are almost same. In LSP, because of very high strain rate(
), HEL(Hugoniot Elastic Limit) is the most important parameter in material behavior modeling. As the circular laser spot is considered, 2-D axisymmetric elements are used and the infinite elements are applied to boundaries for no reflection. The relations of material properties and the LSP are also important parts in this study.
Finite Element Analysis and Evaluation of Rubber Spring for Railway Vehicle
Woo, Chang-Su ; Kim, Wan-Doo ; Choi, Byung-Ik ; Park, Hyun-Sung ; Kim, Kyung-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 773~778
DOI : 10.3795/KSME-A.2009.33.8.773
Chevron rubber springs are used in primary suspensions for rail vehicle. Chevron rubber spring have function which reduce vibration and noise, support load carried in operation of rail vehicle. Prediction and evaluation of characteristics are very important in design procedure to assure the safety and reliability of the rubber spring. The computer simulation using the nonlinear finite element analysis program executed to predict and evaluate the load capacity and stiffness for the chevron spring. The non-linear properties of rubber which are described as strain energy functions are important parameters. These are determined by material tests which are uniaxial tension, equi-biaxial tension and shear test. The appropriate shape and material properties are proposed to adjust the required characteristics of rubber springs in the three modes of flexibility.
Topology Optimization of Geometrically Nonlinear Structure Considering Load-Displacement Trajectory
Noh, Jin-Yee ; Yoon, Gil-Ho ; Kim, Yoon-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 779~785
DOI : 10.3795/KSME-A.2009.33.8.779
This paper is concerned with a computational approach for topology optimization of geometrically nonlinear structures following specific load-displacement trajectories. In our previous works, attention was paid to stabilize topology optimization involving large displacement and a method called the element connectivity parameterization was developed. Here, we aimed to extend the element connectivity parameterization method to find an optimal geometrically nonlinear structure yielding a specific load-displacement trajectory. In contrast to designing a stiffest structure, the trajectory design problem requires special consideration in topology optimization formulation and solution procedure. Some numerical problems were considered to test the developed element connectivity parameterization based formulation.
Structural Topology Design Using Compliance Pattern Based Genetic Algorithm
Park, Young-Oh ; Min, Seung-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 786~792
DOI : 10.3795/KSME-A.2009.33.8.786
Topology optimization is to find the optimal material distribution of the specified design domain minimizing the objective function while satisfying the design constraints. Since the genetic algorithm (GA) has its advantage of locating global optimum with high probability, it has been applied to the topology optimization. To guarantee the structural connectivity, the concept of compliance pattern is proposed and to improve the convergence rate, small number of population size and variable probability in genetic operators are incorporated into GA. The rank sum weight method is applied to formulate the fitness function consisting of compliance, volume, connectivity and checkerboard pattern. To substantiate the proposed method design examples in the previous works are compared with respect to the number of function evaluation and objective function value. The comparative study shows that the compliance pattern based GA results in the reduction of computational cost to obtain the reasonable structural topology.
Surface Relief Hologram Mask Recording Simulation and Optimization Based on SDTA in the Fresnel Diffraction Zone
Lee, Sung-Jin ; Dominguez-Caballero, Jose ; Barbastathis, George ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 793~798
DOI : 10.3795/KSME-A.2009.33.8.793
In this paper, the simulation and optimization of SRH (Surface Relief Hologram) masks for printing LCD gate patterns using TIR (Total Internal Reflection) holographic lithography was investigated. A simulation and optimization algorithm based on SDTA (Scalar Diffraction Theory Analysis) method was developed. The accuracy of the algorithm was compared to that of the RCWA (Rigorous Coupled Wave Analysis) method for estimating the Fresnel diffraction pattern of Cr amplitude masks for the given system geometry. In addition, the results from the optimization algorithm were validated experimentally. It was found that one to the most important conditions for the fabrication of SRH masks is to avoid nonlinear shape distortions of the resulting grating. These distortions can be avoided by designing SRH masks with recorded gratings having small aspect ratios of width versus depth. The optimum gap size between the Cr and SRH masks was found using the optimization algorithm. A printed LCD gate pattern with a minimum line width of
exposed using the optimized SRH mask was experimentally demonstrated.
Prediction of Thoracic Injury of Older Occupant from Belt Loading
Han, In-Seok ; Kim, Young-Eun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 799~806
DOI : 10.3795/KSME-A.2009.33.8.799
Thoracic injury from restraint loading is the principle causative factor of death, which was shown to be particularly significant for older drivers. To characterize thoracic response to belt loading of older drivers, detailed finite element models of the adult and aged thorax were developed. The geometry of the 50th percentile adult male was chosen for the adult FE model. The thoracic FE model was validated against data obtained from results of PMHS pendulum impact tests. The quantified patterns of age-related shape and well-established material changes were applied to the adult model to develop the aged model. Belt force and chest deflection were applied to the developed two types of models. Rib and clavicle fracture risk obviously increased in the aged model. This finding showed that larger rib angle and reduced material properties of the ribcage produced more higher risk of injury in the older driver.
Contribution Analysis Using Shape Simplification Method for Casting Structure Shrinkage
Kwak, Si-Young ; Lim, Chae-Ho ; Baek, Jae-Wook ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 807~812
DOI : 10.3795/KSME-A.2009.33.8.807
Most structure engineers give the casting components over-estimated factor of safety without any reasonable foundation due to the worries about the unavoidable defects such as shrinkages and porosity in castings; the engineers have little knowledge on the relation between the defect and structural behavior. And the workers in casting field also do not know how to control the defects by manufacturing; they do not know to where the defects move or until how size they reduce the defects. In this study, shrinkage defect was scanned by industrial computerized tomography instrument (CT), and subsequently was modeled to a spheroid primitive for structural analysis. Using these simplified models of shrinkage, we observed the effects of the defect on the results of the structural analysis. A commercial structural analysis code was used to do the analysis works. Considering the conclusions, it is possible to manage the shrinkages effectively in casting process and to design the products with more reliable
Selection Method of Global Model and Correlation Coefficients for Kriging Metamodel
Cho, Su-Kil ; Byun, Hyun-Suk ; Lee, Tae-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 813~818
DOI : 10.3795/KSME-A.2009.33.8.813
Design analysis and computer experiments (DACE) model is widely used to express efficiently nonlinear responses in the field of engineering design. As a DACE model, kriging model can approximately replace a simulation model that is very expensive or highly nonlinear. The kriging model is composed of the summation of a global model and a local model representing deviation from the global model. The local model is determined by correlation coefficient with the pre-sampled points, where the accuracy and robustness of the kriging model depends on the selection of proper correlation coefficients. Therefore, to achieve the robust kriging model, the range of the correlation coefficients is explored with respect to the degrees of the global model. Based on this study we propose the proper orders of the global model and range of parameters to make accurate and robust kriging model.
Strength Analysis of Bolt Joints for an Open Frame Structure
Lee, Jin-Min ; Lee, Min-Uk ; Cho, Su-Kil ; Koo, Man-Hoi ; Gimm, Hak-In ; Lee, Tae-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 819~825
DOI : 10.3795/KSME-A.2009.33.8.819
An open frame structure is fastened by bolt joints for strength and shock attenuation. Therefore the full finite element model of an open frame structure should be properly modeled including bolt joints for strength analysis of the frames and joint assemblies which are operated under multi-loading conditions such as driving, drop, inertia and torsional loads. Then the joints and frames must satisfy the specified allowable strength constraints. Because the full finite element model has a large number of elements to perform strength analysis, a detailed fine bolt analysis seems to be very expensive. Therefore bolts of the full finite element model are approximately modeled by coupling method to constrain degree of freedoms between adjacent nodes. However, the coupling method can exaggerate stress results at the constrained nodes. Thus a detailed bolt analysis and a theoretical/experiential formula of bolts for a worst bolt joint are performed using reaction force applied both bolt and bolt joint. Finally, the results from the two methods are compared and discussed to verify the safety of the open frame structure.
Investigation of the Performance Based Structural Safety Factor of Elbows in Nuclear Power Plants
Lee, Sung-Ho ; Park, Chi-Yong ; Park, Jai-Hak ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 826~831
DOI : 10.3795/KSME-A.2009.33.8.826
The piping systems in nuclear power plant are composed of various typed pipes such as straight, elbow pipe, branch and reducer etc. The elbow is connected from straight pipe to another pipes in order to establish the complicated piping system. Elbow is one of very important components considering management of wall thinning degradation. It is however applied by various loads such as system pressure, earthquake, postulated break loading and many transient loads, which provoke simply the internal pressure, bending and torsional stress. In this study, firstly pipes in the secondary system of the nuclear power plant are classified as pipe size and type for selecting the investigating range. Next, a large number of finite element analysis considering the all typed dimensions of commercial pipe has been performed to find out the behavior of TES(twice elastic slop) plastic load of elbows, which is based on evaluation of the structural safety factor. Finally performance based structural safety factor was investigated comparing with maximum allowable load by construction code.
Estimation Model of Contact Wheels for UGV with Actively Articulated Suspensions
Lim, Kyeong-Bin ; Kim, Sun-Je ; Park, Suk-Hoon ; Yoon, Yong-San ; Lee, Sang-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 832~841
DOI : 10.3795/KSME-A.2009.33.8.832
Wheels of UGV can be used to get the information about the ground. However, wheels of UGV with actively articulated suspension cannot be used as the roles because the each wheel does not remain in contact with the ground. Therefore, in this study, we proposed the indexes and models to estimate the contact wheels. First, we formulated the dynamic equations about the actively articulated suspensions and wheels. Then estimation index
were developed from the equations, and analyzed the strengths and weaknesses of each index. As the results, we developed the fuzzy rule-based estimation model additionally derived from our observations.
model could eliminate the noise of about 60% in comparison with the result without the estimation model. Fuzzy model also could reduce the noise of about 83%. In addition, fuzzy rule-based estimation model had high sensitivity and precision as well as robustness.
Research for Fatigue Life Extension Techniques in Weldments via Pneumatic Hammer Peening
Han, Jeong-Woo ; Han, Seung-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 842~848
DOI : 10.3795/KSME-A.2009.33.8.842
Fatigue failures are often occurred at welded joints where stress concentrations are relatively high due to the joint geometry. Although employing good detail design practices by upgrading the welded detail class enables to improve the fatigue performance, in many cases, the modification of the detail may not be practicable. As an alternative, the fatigue life extension techniques that reduce the severity of the stress concentration at the weld toe region, remove imperfections and introduce local compressive welding residual stress, have been applied. These techniques are also used as definite measures to extend the fatigue life of critical welds that have failed prematurely and have been repaired. In this study, a hammer peening procedure for using commercial pneumatic chipping hammer was developed, and the effectiveness is quantitatively evaluated. The pneumatic hammer peening makes it possible to give the weld not only a favorable shape reducing the local stress concentration, but also a beneficial compressive residual stress into material surface. In the fatigue life calculation of non-load carrying cruciform specimen treated by the pneumatic hammer peening, the life was lengthened about ten times at a stress range of 240MPa, and fatigue limit increased over 65% for the as-welded specimen.
Development of Patrol Robot System for Thermal Power Plant Facilities
Park, Joon-Young ; Lee, Jae-Kyung ; Cho, Byung-Hak ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 8, 2009, Pages 849~857
DOI : 10.3795/KSME-A.2009.33.8.849
To guarantee the safety and reliability of obsolete thermal power plants, on site routine patrol in their facilities has been done by human workers. Due to their poor working environments, however, a patrol robot system has been gradually required instead of the human workers from the viewpoint of the workers' safety and work efficiency. For this purpose, this paper presents a patrol robot, controllers, and its control scheme. Especially, this robot system uses a line tracing algorithm, which uses a vision camera instead of IR sensors, and an RFID system for its patrol operation. We confirmed its effectiveness through experiments.