• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.265-274
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• 2015

The structural safety of nuclear power plant against impact from aircraft crash has been performed so far in two viewpoints such as local behavior and global behavior, and the local behavior has been evaluated using local damage evaluation formulas suggested based on the results of experimental data of RC (Reinforcement Concrete) wall. However, few data have been collected from recent research to evaluate the local behavior and damage of SC (Steel plate reinforced Concrete) wall, which is recently applied to the newly designed nuclear power plant. In this study, local damages of SC wall and RC wall against an idealized aircraft engine projectile impact are evaluated through FE simulation analyses with various wall thicknesses and steel ratio. Through analysis of local collision simulation results of SC and RC wall, the penetration depth of SC wall and RC wall are compared.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4A
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• pp.311-321
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• 2011

To analysis the effect of reinforcement ratio and impact velocity on local damage, a series of impact analyses are performed to predict local effects. According to these results, the reinforcement ratio has no effect on the penetration depth and perforation thickness, but notable change to the scabbing area were observed. The higher the missile velocity becomes, the greater the degree of local damage to the reinforced concrete slabs is. Analysis results will be useful in the impact-resistance design of containment buildings and structures.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.6
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• pp.373-380
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• 2018

We present the peridynamic dynamic fracture analysis to solve impact fracturing of multilayered glass impacted by a high-velocity object. In the most practical multilayered glass structures, main layers are glued by thin elastic masking films. Thus, it is difficult and expensive to construct the numerical model for such a multilayered structure. In this paper, we employ efficient numerical modeling of multilayered structures with a nonlocal ghost interlayer model in which ghost particles are distributed between main layers and they are interacting with each other in peridynamic way. We also consider a simple nonlocal contact condition in peridynamic frameworks to solve impact and penetration of the high-velocity impactor to the multilayered structure. Finally we can confirm the fracture capabilities of the method using a multilayered glass model in which 7 glass layers and a single elastic backing layer are affixed by polyvinyl butyral films.

• Tunnel and Underground Space
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• v.29 no.6
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• pp.480-507
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• 2019

This paper aims at optimizing the auxiliary ventilation system in large-opening limestone mines with unducted fans. An extensive CFD and also site study were carried out for optimization at the blind entries. The fan location, operating mode, and layout are the parameters for optimization. Since the jet stream discharged from the auxiliary fan is flowing faster than 15 m/s in most of the cases, the stream collides with floor, sides or roof and even with the jet stream generated from the other fan placed upstream. Then, it is likely to lose a large portion of its inertial force and then its ventilation efficiency drops considerably. Therefore, the optimal fan installation interval is defined in this study as an interval that maximizes the uninterrupted flowing distance of the jet stream, while the cross-sectional installation location can be optimized to minimize the energy loss due to possible collision with the entry sides. Consequently, the optimization of the fan location will improve ventilation efficiency and subsequently the energy cost. A number of different three-dimensional computational domains representing a full-scale underground space were developed for the CFD study. The velocity profiles and the CO concentrations were studied to design and optimize the auxiliary ventilation system without duct and at the same time mine site experiments were carried out for comparison purposes. The ultimate goal is to optimize the auxiliary ventilation system without tubing to provide a reliable, low-cost and efficient solution to maintain the clean and safe work environment in local large-opening underground limestone mines.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6A
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• pp.543-560
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• 2010

Safety-related concrete structures in a nuclear power plant must be protected against the impact of flying objects, referred to in the profession as missiles. In practice, the structural verification is usually carried out by means of empirical formulas, which relate the velocity of the impinging missile to the wall thickness needed to prevent scabbing or perforation. The purpose of this study is to reevaluate the predictability of the local effect prediction formulas for the penetration and scabbing depths and perforation thickness. Therefore, available formulas for predicting the penetration depth, scabbing thickness, and perforation thickness of concrete structures impacted by solid missiles are summarized, reviewed, and compared. A series of impact analyses is performed to predict the local effects of the projectile at impact velocities varing from 95 to 215 m/s. The results obtained from the numerical simulations have been compared with tests that were carried out at Kojima to validate numerical modelling. The simulation results show reasonable agreement with the Kojima test results for the overall impact response of the RC slabs. From these results, it seems that the Degen equation give a very good estimate of perforation thickness against a tornado projectile for test data. Finally, the results obtained from the impact analysis have been compared with Degen formula to determine the perforation thickness of the RC slab.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.30-31
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• 2009

Through the full scale ship collision response analysis of high speed passenger ship with underwater floating matters, the objective of this study is to perform the crashworthy safety assessment of its hull and passengers. For this safety assessment, diverse collision scenarios could be established through the thorough understanding of damage mechanisms due to the collision of its hydrofoil system with underwater floating matter examining the damage informations of its hull and passengers from the collision accidents, and through the estimation of the damages of its hull and passenger. The next step, crashworthy safety assessment of its hull and passengers, was carried out by the collision response analyses of high speed passenger ship with underwater floating matter using Fluid-Structure Interaction(FSI) analysis technique of LS-DYNA code in consideration of surrounding water, and using local zooming analysis technique.

• Journal of the KSME
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• v.35 no.8
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• pp.698-708
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• 1995

충돌이란 두 개 이상의 물체가 특정한 상대 속도로 부\ulcorner칠 때 나타나는 현상으로서 준 정 적(quasi-static) 조건하에서 나타나는 현상과 크게 다음 두 가지 특징을 들 수 있다. 첫째, 관 성력이 매우 중요하다. 따라서 기본 역학 및 물리학 보존법칙에 기초를 둔 모든 지배 방정식에 이 영향을 반드시 포함시켜야 한다. 둘째, 응력파(stress wave)에 의한 재료의 변형을 들 수 있다. 이 응력파는 시간과 거리에 따라 급격히 감소되므로 대부분의 경우 국부적으로 많은 변형이 일 어난다. 충돌에 의하여 일어나는 재료의 변형 특성은 충돌 속도에 따라 매우 다르게 나타난다. 이러한 특징들을 표 1에 나타내었다. 이 글에서는 충돌 해석 프로그램의 특징과 구성을 소개하고 그중 엑스플리시트 유한요소방법을 사용한 금속 재료에 관련된 몇 가지 충돌현상의 해석 예를 소개하고자 한다.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.4
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• pp.13-21
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• 2011

Seismic structure pounding between adjacent superstructures may induce the destruction of pier and bridge superstructures and cause local damage that leads to the collapse of the whole bridge system. The pounding problem is related to the expansion of joints, gap distance and seismic response of the abutments. In this research, methods of the contact element approach, the linear spring model, the Kelvin-Voigt model and the Hertz model were studied to analyse the pounding characteristics. The shaking table test for a model specimen such as a bridge superstructure with elastomeric bearings was performed to evaluate the contact element approach methods. Relationships between the time history response from the numerical analysis results and the measured response from the shaking table test are compared. The experimental results were not well matched with the numerical analysis results using the existing pounding stiffness models. Therefore, in this study, coefficients are proposed to calculate the appropriate pounding stiffness ratio.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.103-117
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• 1995

A design-oriented method for analysis of the structural damage due to ship collisions is developed by using the idealized structural unit method(ISUM). The method takes into account yielding, crushing, rupture, the coupling effects between local and global failure of the structure, the influence of strain-rate sensitivity and the gap/contact conditions. The method is verified by a comparison of experimetal and numerical results obtained from test models of double-skin plated structures in collision/grounding situations with the present solutions. As an illustrative example, the method has been used for analyses of a side collision of a double-hull tanker. Several factors affecting ship collision response. namely the collision speed and the scantlings/arrangements of strength members, are discussed.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05b
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• pp.1063-1066
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• 2003

지능형 게임 개발을 위하여 게임 이론의 정의, 게임의 구성요소, 전략적 게임의 분석을 통해 게임에 대한 배경 환경을 살펴보고, 보다 사실적 느낌 전달을 위한 게임 애니메이션과 게임에 적용되는 인공지능 기술을 퍼지 이론, 뉴럴네트웍으로 분류하여 적용 현황을 살펴보았다. 즉 게임처럼 수학적 표현이 어려운 경우 해결점을 퍼지 이론에서, 캐릭터의 움직임을 제어하는 퍼지 Rule Base를 찾아내는 연구를 신경망 인공지능을 통해 해결하는 과정을 살펴보고 국부해의 단점을 갖는 신경망 인공지능의 불투명성 해결 방법을 유전자 알고리즘에서 찾았다. 결론적으로 게임에서 이루어지는 물리적 특성인 충돌에 대한 충돌검사 알고리즘, 충돌반응에 대한 최적화를 유전자 알고리즘을 적용하여 해결하였다.