• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.10
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• pp.1054-1064
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• 2009

In this work, we predict a true fracture strain using load-displacement curves from tensile test and finite element analysis (FEA), and suggest a method for acquiring true stress-strain (SS) curves by predicted fracture strain. We first derived the true SS curve up to necking point from load-displacement curve. As the beginning, the posterior necking part of true SS curve is linearly extrapolated with the slope at necking point. The whole SS curve is then adopted for FE simulation of tensile test. The Bridgman factor or suitable plate correction factors are applied to pre and post FEA. In the load-true strain curve from FEA, the true fracture strain is determined as the matching point to test fracture load. The determined true strain is validated by comparing with test fracture strain. Finally, we complete the true SS curve by combining the prior necking part and linear part, the latter of which connects necking and predicted fracture points.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5696-5703
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• 2012

In this study, the characteristics of filter that make up the automotive airbag system were analyzed. The gas pressure change of airbag is directly impacted by the filter. However, it is uncertain how much the design factors of filter affect the pressure of airbag. And it is difficult to access the pressure loss coefficient in the respect of characteristics of the airbag filter in the simulation method. To solve this problem, this study suggests pressure loss coefficient of the filter using simulation analysis. But it is impossible to interpret a sudden increase of pressure such as airbag filter. To solve this problem, by applying interpolation and scale down method, analysis was processed. Also, through the simulation interpretation of airbag filter's pressure loss coefficient, the guidelines for the filter design could be suggested.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.5
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• pp.399-407
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• 2007

Two reliability models, AFDA(Approximate Full Distribution Approach) and Monte-Carlo simulation method, are directly developed to study on both hydraulic failure mode of berm recession and structural failure mode of armour breakage of berm breakwaters. By comparing the present results with the results of other researcher, it may be confirmed that two reliability models can be straightforwardly applicable to berm breakwaters. Relative influence of each random variable on hydraulic and structural failure probabilities could be properly analyzed. The upper bound and the lower bound of failure probability can be evaluated by using bi-modal bounds of the multiple failure mode analysis, from which it may be possible to investigate some kinds of dependence into between two failure modes. Finally, it may also be found that the structural failure mode of armour breakage could become a main failure mode of berm breakwaters in the condition of more than any allowable berm recession.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.205-210
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• 2006

The impact forces of the highly nonlinear waves are one of the important factors in designing the ocean structures. The impact forces are very difficult to analyze numerically and experimentally because they are impulsive in magnitude and occur instantaneously. In this study the numerical program based on N.S. equations are used to investigate the impact forces of steep waves where the waves are gene rated by the wave maker in the numerical wave basin. The arbitrary steep waves are generated by the superposition of waves of single frequency and the impact forces on vertical cylinder are simulated on the multiblock grids. V.O.F. and the local height function methods are used to track the free surfaces. To validate the numerical analysis the numerical results are compared with the experimental ones and the acceptable agreements are found. It is thought that more studies on the simulations of the incoming breaking waves and the impact forces on the vertical cylinder should be made to obtain the useful results to be applied in the offshore design.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.540-540
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• 2012

강우 발생시 유역에 집수된 물이 하천에 이르는 경로에 따른 유출은 지표유출, 지표하유출, 지하수유출로 구분된다. 정확한 수문순환 과정의 해석을 위해서는 지표 흐름뿐만 아니라 지표하 및 지하수 흐름의 해석이 중요한 실정이나 일반적으로 실무에서 사용되는 강우-유출해석 모형은 지표유출을 해석하기 위한 모형이 대부분이며, 지표하 유출과 침투량을 산정하는데 어려움이 있다. 일반적인 강우-유출해석 모형은 Horton 방법, NRCS 방법, Green-Ampt 방법에 의해 유효우량을 분리하며, 이 과정은 침투량을 직접적으로 모형화 할 수 없으므로 지표 및 지표하, 지하수 흐름을 복합적으로 해석할 수 있는 모형이 질적이나 양적으로 부족한 실정이다. 이러한 지표하 흐름과 침투량을 산정하기 위하여 FE-FLOW, PM, MS-VMS, GMS, GW-VISTAS, ARGUS 및 MODFLOW와 같은 지하수 모형을 사용하고 있다. 본 연구에서는 지표하유출 산정을 위한 침투량의 비교분석을 위해 현재 가장 범용되는 지하수 유동 모델링 프로그램인 Visual Modlfow 모형과 GMS 모형을 이용하여 침투량 산정을 위한 수치 모의를 진행하였다. 각 모형의 입력자료는 2009년 국립방재연구원에서 수행한 침투실험시설 자료를 이용하여 동일한 조건을 부여하고, 두 모형의 비교를 위해 Visual Modflow에서는 MODFLOW의 기본 해석방법인 유한차분법(FDM)을 이용하고, GMS 모형에서는 3차원 유한요소해석이 가능한 GMS-FEMWATER를 이용하였다. 두 모형의 수치모의 조건으로 2009년 국립방재연구원에서 수행한 침투실험방법과 동일하게 공극률에 따른 투수성 보도블럭의 구분과 50mm/hr, 100mm/hr, 150mm/hr, 200mm/hr의 강우강도별 선행함수조건에 따른 수치모의를 진행하였으며, 수치모의된 침투량의 적정성을 판단하기 위하여 국립방재연구원의 침투실험 결과자료와 비교분석하였다. 침투실험 자료와 각각 수치모의된 침투량을 비교분석한 결과 서로 유사한 경향을 보이고 있으나 초기 침투시 상대오차가 비교적 크게 발생하였다. 이는 수치모형의 경우 수리실험과는 다르게 모의시작과 동시에 해당 강우강도의 침투가 시작되므로 초기 유입 유출량 발생시간의 차이가 종료시간까지 누적 침투량에 미치는 것으로 판단되며, 매개변수에 많은 영향을 받는 것으로 판단된다.

• The Journal of Korean Philosophical History
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• no.52
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• pp.37-67
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• 2017

This article is to examine the characteristics of Habin Sin Hu-Dam's method of interpreting Zhouyi and to review its position in Zhouyi history of Joseon Dynasty. Especially, there has been drown attention to the connection both Habin and Tasan Cheong Yagyong. Habin is a philosopher who consistently interprets Zhouyi through the inner logic of it, not through Neo-confucian framework of it. The inner logic is yaobian theory, which is found through investigating the auguries in the old Books of Confucianism. It could be said that this discovery is the Habin's original one, although there may be historically connections between him and Seong-Ho School in the interpreting methodology about Zhouyi. However, at a future date this logic is found in Tasan. There are no connections between two philosophers, but it may be said that they arrive at the common method of interpreting Zhouyi through investigating the auguries in the old Books of Confucianism. We find that their common methods of interpreting Zhouyi do not keep to authoritative interpretation, but there is the passion of searching for Zhouyi the way as it is.

• The Journal of the Korea Contents Association
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• v.21 no.6
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• pp.678-686
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• 2021

A smiling face usually has a positive effect on interpersonal relationships by delivering a warm impression. However, the stereotype content model and compensation effect between warmth and competence suggested that warmth perceptions caused by a smiling face could influence competence perceptions negatively. This study examined the negative impact of the advertising endorser's smile on purchase intention in an expensive product category by adopting the self-construal level. The study results showed that consumers with independent-self construal (vs. interdependent self-construal) showed a lower purchase intention when exposed to an ad containing an endorser's smile. In comparison, consumers with interdependent-self construal (vs. independent self-construal) showed a lower purchase intention when exposed to an ad without an endorser's smile. Thus, this study demonstrated a moderating role of self-construal in the relationship between advertising endorser's smile and purchase intention. These findings provide valuable theoretical and practical implications for effective advertising strategies in the expensive product category.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.34 no.4
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• pp.93-99
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• 2022

Analytical solutions for regular waves generated by bottom wave makers in a 3-dimensional wave basin were derived in this study. Bottom wave makers which have triangular, rectangular and combination of two shapes were adopted. The 3-dimensional velocity potential was derived based on the linear wave theory with the bottom moving boundary condition, kinematic and dynamic free surface boundary conditions in a wave basin. Then, analytical solutions of 3-dimensional particle velocities and free surface displacement were derived from the velocity potential. The solutions showed physically valid results for regular waves generated by bottom wave makers in a wave basin. The analytical solution for obliquely propagating wave generation from bottom wave maker which works like a snake was also derived. Numerical results of the solution agree well with theoretically predicted results.

• Geotechnical Engineering
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• v.13 no.1
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• pp.5-18
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• 1997

In order to make reliable ground shock predictions in saturated geological media, it is necessary to use multi -phase material models and numerical codes. This paper presents the results of theoretical study of the fundamental behavior of multi-phase porous media subjected to high dynanlic loadings, and deals with the development of numerical code MPDAP with JWL(Jones-Wilkins-Lee) model, which is capable of considering the kinds and characters of explosives. To check the global equilhorium equations of the numerical code, we carried out some verifications. In the cases of the elastic spherical wave propagation in a single phase medium, one-dimensional linear ronsolidation, and one timensional wave propagation in saturated linear elastic soils and rocks, the results calculated by MPDAP show close agreement with closed-form solutions or numerical solutions generated with two phase code.

• School Mathematics
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• v.9 no.3
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• pp.375-396
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• 2007

The purpose of this study is to analyze how a mathematics teacher and a high school student make the meaning in a graph and how aspects of the interpretation of a graph are interacted during the signification process, and to suggest considerations for teaching and learning of a graph. The findings of a case study have led to conclusions as follows: All of them have a difficulty in making the meaning in a graph and construct the meaning as a nested signification model. In the process which they make the meaning, they interrelate cognitive, contextual, and affective aspects and construct interpretants. In this process, a teacher focuses on cognitive aspect, based on a qualitative approach. But a student considers contextual aspect more, based on a quantitative approach. This study suggests three considerations for teaching and learning of a graph.