• 한국터널지하공간학회 논문집
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• 제23권6호
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• pp.485-502
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• 2021

터널 굴착으로 인해 필연적으로 발생되는 지반침하 및 상부 구조물 영향 평가를 수행하기 위해 지표침하와 구조물 건전도 저감의 총 7개의 주요 영향 인자들을 설정하고 수치해석을 이용한 Parameter Study를 수행하였다. 그 결과를 통해 Boscardin and Cording 구조물 손상도표를 이용한 안정성 분석, 최대침하량과 각변위를 이용한 안정성 분석을 수행하고 각각의 주요 영향 인자들에 대한 상관성 분석을 실시하였다. 또한, 매개변수 해석을 통한 지반 및 구조물 상호거동 양상을 이용하여 경기도 화성시에 위치한 𐩒𐩒𐩒터널 현장에 적용하고 현장 적용성을 분석하였다. 그 결과 오차가 약 1.0%로 나타나 설계단계에서의 터널 굴착에 따른 구조물 안정성 평가 시 다양한 조건에서 적합한 노선 결정을 위한 기초 자료로 활용될 수 있도록 하였다.

• 대한기계학회논문집A
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• 제21권5호
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• pp.828-834
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• 1997

The knowledge of material stress-strain behavior is an essential requirement for design and analysis of deformation processes. Empirical stress-strain relationship and constitutive equations describing material behavior during deformation are being widely used, despite suffering some drawbacks in terms of ease of development, accuracy and speed. In the present study, back-propagation neural networks are used to model and predict the flow stresses of a HSLA steel under conditions of constant strain, strain rate and temperature. The performance of the network model is comparedto those of statistical models on rate equations. Well-trained network model provides fast and accurate results, making it superior to statistical models.

• Structural Engineering and Mechanics
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• 제75권6호
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• pp.713-722
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• 2020

This article aims to illustrate the damped dynamic responses of layered functionally graded (FG) thick 2D beam under dynamic pulse sinusoidal load by using finite element method, for the first time. To investigate the response of thick beam accurately, two-dimensional plane stress problem is assumed to describe the constitutive behavior of thick beam structure. The material is distributed gradually through the thickness of each layer by generalized power law function. The Kelvin-Voigt viscoelastic constitutive model is exploited to include the material internal damping effect. The governing equations are obtained by using Lagrange's equations and solved by using finite element method with twelve -node 2D plane element. The dynamic equation of motion is solved numerically by Newmark implicit time integration procedure. Numerical studies are presented to illustrate stacking sequence and material gradation index on the displacement-time response of cantilever beam structure. It is found that, the number of waves increases by increasing the graduation distribution parameter. The presented mathematical model is useful in analysis and design of nuclear, marine, vehicle and aerospace structures those manufactured from functionally graded materials (FGM).

• 한국정밀공학회지
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• 제16권8호
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• pp.28-37
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• 1999

This investigation is the result of the structural analysis by finite element method and test for considering stress distribution and stress concentration to be generated according to the change of attached shape and method of the bracket to pipe in welding structure. Generally, members that consist structures are subjected to various forces and are jointed each other with a number of bracket. In this case, circular pipe was adapted in order to weld these members easily and to study the optimal design which is used a beam with shape section as main components of the structure, According to attached shape and method, distributed stress on circular pipe is appeared so differently. This may result deeply effects with respect to thickness, material properties. So a study on attaching shape and method of bracket to circular pipe is needed. In this paper, to obtain the maximum equivalent stress or stress concentration was used experimental and F.E.M. analysis. First five parameter was defined with respect to attached a shape and method to circular pipe i.e. the variation of the attached area, the variation of the attached shape, the variation of the attached length, the variation of both directin angles, the variation of the upper angle. Afterward the experimental analysis was practiced as the variation of the both direction angel and the finite element analysis was practiced as each parameters. We can discover stress distribution and stress concentration according to the change of form of bracket. And the result can be referenced for a design of similar structure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.451-455
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• 2003

Major concern in modern industry is how to reduce the time and cost for product efficient production. Among many mechanical parts of a satellite, bracket plays an important role to support the load when the satellite is launched to space. so enough strength and stiffness. A designer could add unnecessary material and strength it so as not to fail when it used. But if mechanical part of satellite is over-designed, cost will rise and it also goes against to the aim of lightness. To achieve lightness and enough strength and stiffness, optimization algorithm should be introduced in design process. In this study, conceptual design of bracket is carried out to increase the performance of satellite. Some parameter which could change the weight of this part are selected as design variables. Total weight of bracket is to be minimized while displacement and stress should not exceed limit. Size optimization is done with 3D solid element and PLBA, the RQP algorithm. The weight of 0.262kg of initial model is reduced to 0.241kg after optimization process, so 9.8% of weight reduction is obtained.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권3호
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• pp.185-191
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• 1999

The fuse used in the high voltage distribution line often fails due to the active ionization caused by the strong electric field at fuse terminal. To suppress the ionization at the high voltage and high capacity current limiting fuse, the particle size and compactness of silica sand, the design, length, notch number and material of element, the diameter and length of fuse body must be considered carefully. However, these are not many proper which is treated with the inherent interrupting characteristics from many parameters at present. Because of these reasons, time and effort are needed to develop the new type fuse by the fuse designers in relation with the inherent characteristics from each of parameters. In this paper we choose 7 parameters with weight value based on study and experimentation and analyzed the characteristics of arcing period. In addition, we proposed the experimental method to experimentation and analyzed the characteristics of arcing period. In addition, we proposed the experimental method to extract the optimal design parameters with minimal effort as related the mutual effect from each of the parameters.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.102-109
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• 2001

In order to take account of the statistical properties of probability variables used in the structural analysis, the conventional approach using the safety factor based on past experience usually estimated the safety of a structure. The real structures could only be analyzed with the error in estimation of loads, material characters and the dimensions of the members. But the errors should be considered systematically in the structural analysis. Structural safety could not precisely be appraised by the traditional structural design concept. Recently, new approach based on the probability concept has been applied to the assessment of structural safety using the reliability concept. Thus, the computer program by the Probabilistic FEM is developed by incorporating the probabilistic concept into the conventional FEM method. This paper estimated for the reliability of a plane stress structure by Advanced First-Order Second Moment method using von Mises, Tresca and Mohr-Coulomb failure criterions. The reliability index and failure probability of attained by the Monte Carlo Simulation method with the von Mises criterion were same as PFEM, but the Monte Carlo Simulation were very time-consuming. The variance of member thickness and load could influence the reliability and failure probability most sensitively among the design variables from the results of the parameter analysis. And proper failure criterion must be used to design safely.

• Bulletin of the Korean Chemical Society
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• 제34권1호
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• pp.79-88
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• 2013

$LiFePO_4$ is a promising active material (AM) suitable for use in high performance lithium-ion batteries used in automotive applications that require high current capabilities and a high degree of safety and reliability. In this study, an optimization of the electrode design parameters was performed to produce high capacity lithium-ion batteries based on $LiFePO_4$/graphite electrodes. The electrode thickness and porosity (AM density) are the two most important design parameters influencing the cell capacity. We quantified the effects of cathode thickness and porosity ($LiFePO_4$ electrode) on cell performance using a detailed one-dimensional electrochemical model. In addition, the effects of those parameters were experimentally studied through various coin cell tests. Based on the numerical and experimental results, the optimal ranges for the electrode thickness and porosity were determined to maximize the cell capacity of the $LiFePO_4$/graphite lithium-ion batteries.

• 한국기계가공학회지
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• 제21권9호
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• pp.110-116
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• 2022

As the spread of COVID-19 continues, cleanliness and quarantine are emphasized in daily life. If foreign substances enter through the shoe sole when using public facilities, cleanliness may deteriorate and various infections may occur. To prevent this, shoe sole cleaners that filter out foreign substances have been developed. In this study, a design that satisfies structural safety was presented by selecting a new material and updating the design parameter to reduce the weight of the shoe sole cleaner. To evaluate the structural safety, a finite element analysis under selected design loads was performed. Through design improvement and stress analysis, a model that was approximately 85% lighter than the existing model was developed.

• Elastomers and Composites
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• 제47권3호
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• pp.188-193
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• 2012

고무부품의 신뢰성을 확보하기 위해서는 피로수명예측 및 평가기술 개발이 중요하다 하겠다. 최근에 고무부품에 대한 고 성능, 고 신뢰성을 위해 설계, 해석 및 평가기술이 요구되고 있으나, 지금까지는 경험과 시행착오적인 방법으로 개발되고 있는 실정이다. 따라서, 본 연구에서는 고무소재에 대해 배합조건, 기계적 특성, 열화 및 피로수명 등을 포함하는 고무소재 물성 데이터베이스를 구축하고, 고무부품의 특성해석 결과를 데이터베이스와 연계하여 고무부품의 피로해석 모델을 개발하였으며, 실제 피로시험 결과를 통하여 개발된 모델의 타당성을 검증하였다.