• 한국안전학회지
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• 제27권6호
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• pp.7-13
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• 2012

A lack of study on the dynamic tensile strengths of Sn-based solder joints at high strain rates was the motivation for the present study. A modified miniature Charpy impact testing machine instrumented with an impact sensor was built to quantitatively evaluate the dynamic impact strength of a solder joint under tensile impact loading. This study evaluated the tensile strength of lead-free solder ball joints at strain rates from $1.8{\times}10^3s^{-1}$ and $8.5{\times}10^3s^{-1}$. The maximum tensile strength of the solder ball joint decreases as the load speed increases in the testing range. This tensile strength represented that of the interface because of the interfacial fracture site. The tensile strengths of solder joints between Sn-3.0Ag-0.5Cu and copper substrate were between 21.7 MPa and 8.6 MPa in the high strain range.

• Nuclear Engineering and Technology
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• 제42권4호
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• pp.394-413
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• 2010

The object of this paper is to identify the key elements that impact a radiation dose at EAB (Exclusion Area Boundary). This study is based on the AST (Alternative Source Terms) as defined in Regulatory Guide 1.183. The LOCA (Loss of Coolant Accident) and the LRA (Locked Rotor Accident) are selected as limiting cases. A sensitivity analysis of accidental behavior with respect to various parameters during LOCA and LRA at Kori Unit 1 is also undertaken for the following objectives: to determine the limiting parameters, to find the impact trend of the radiation dose, and to find the safety margin between AST and TID (Technical Information Document) methodologies. This work confirms that key parameters are particulate removal rate, decontamination factor, iodine chemical form, gap fraction, partitioning factor, and the impact of isotopes group. Comparing TID with AST, the radiation dose of TID is about 80% greater than that of AST under a LOCA, and about 60% greater than that of AST for the case of a LRA; thus the safety margin is remarkably increased when the AST is used. In this work, the sensitivity analysis results are presented in terms of a sensitivity index called the "NDD (Normalized Dose Difference)", which compares the impact of parameters with that of a reference case. These values are derived by using a combination of the leak rate (primary to secondary), iodine chemical form, gap fraction, partitioning factor, spray removal rate, source term, and other variables.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1993년도 추계학술대회논문집
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• pp.243-251
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• 1993

With the recent issuance of a dynamic side impact test regulation in the Federal Motor Vehicle Safety Standard in the United States of America, many aspects of occupant protection in side impact crashes have been under investigation. Many investigations of real world accidents, crash test results and simulation studies have established that in side impact crashes of passenger cars, thoracic and pelvic injuries of occupant are, large part, caused by occupants' impact against the interior side of the vehicle, primarily the door. This paper is concerned with the development of a lumped mass computer model, which simulates the interaction of a struck car door and an adjacent seated occupant in side impacr, based CTP code which has been successfully used in vehicle and occupant simulation. New model developments include elimination of influence of vehicle side structure stiffness in the occupant injury responses. The model was used to investigated the effect of various door padding characteristics on occupant responses to improve vehicle safety performance. The evaluation of different crush properties of door padding have also focused to understand of behavior of impacted occupant. Results from simulations, The effects of both material coefficients $C_{f}$ and p were illustrated in terms of occupant injury criteria TTI and pelvis.

• 해양환경안전학회지
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• 제16권1호
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• pp.49-55
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• 2010

해상에서 유류유출사고가 발생하면 해양생태계 파괴 뿐 아니라 바다에 의존하여 삶을 영위하는 인간에게 사회경제적으로 미치는 영향이 크다. 법률(해양환경관리법)에서는 유류유출시 해양오염영향조사를 하도록 규정하고 있지만, 사회경제적 영향을 평가하기에는 법률상 조사 항목이 구체적이지 못하고, 세부항목 간 중복 등의 문제가 있다. 본 연구에서는 법률상 해양오염영향조사 시스템 중 사회경제 분야의 조사를 중심으로 문제점을 진단하고, 사회경제적 영향평가의 범주와 지표를 개발하여 제도적 개선의 방안을 제시하였다.

• 대한토목학회논문집
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• 제30권6D호
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• pp.605-613
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• 2010

본 연구에서는 소형차도로 방호울타리 형식선정의 필수요소인 충돌계수 분석 및 방호울타리 높이 선정을 위해 현재의 기준을 적용하는 과정에서 생긴 문제점을 파악하여 개선점을 제시하고 이를 해외기준과 비교분석하여 방호울타리의 형식결정을 위한 기준을 제시하였다. 이를 위해 소형차관련 사고사례분석을 실시하였고, 사고사례를 토대로 방호울타리의 형식선정에 중요인자인 충돌각도, 충돌차량, 충돌속도를 비교 분석 및 소형차 방호울타리의 소요높이를 결정하였다. 충돌각도의 경우 편도 2차로 고속도로 사고사례를 분석하여 유럽 RISER 연구 결과와 비교하여 상향조정의 필요성을 도출하였다. 충돌차량의 경우 경차, 소형승용차, 중형 및 대형승용차, 승용차(SUV), 승합차 및 소형 트럭으로 나누어 분석을 실시하였으며, 충돌사고소형차 사고누적율에 기반한 차량중량 및 충돌속도를 회귀분석하였으며 수도권고속도로 누적통행비율을 감안 충돌중량을 결정하였다. 또한 그 결과를 토대로 소형차도로 방호울타리 높이를 계산하였다. 본 연구의 결과는 향후 소형차도로 형식선정에 중요한 인자가 된다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.264-267
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• 2005

Impact damages are very important in the perspective of residual strength of composite structures such as aircrafts, ships, and trains because those damages are sometimes not visible on the surface of the point of impact and the impact resistance of laminated composites is usually not so high. Thus, the impact characteristics of laminated composites should he investigated for the safety of composite structures. This paper investigates the low-velocity impact and damage detection conducted on woven carbon/epoxy laminates. Experimental results show that the type of damage is dependent on the impact energy level and the delamination area becomes larger as the impact energy increases.

• 한국항행학회논문지
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• 제12권4호
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• pp.295-303
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• 2008

고속으로 장거리를 비행하는 위성발사체는 고장 시 큰 위험을 줄 수 있으므로, 비행 궤도를 감시하고 고장여부를 판단하는 비행안전 시스템의 운용이 필수적이다. 비행안전 시스템에 적용되는 필터는 일반적인 위치추적 필터와는 달리 필터 정확성 보다는 신뢰성이 우선 시 되어야 하고, 정확한 순간낙하점 추정을 위해서는 궤도 위치뿐만 아니라 속도 역시 중요하게 여겨져야 한다. 본 논문에서는 KSLV-I 위성발사체 발사 시 운용되는 추적 센서를 적용하는 융합필터를 구성하고 궤도 및 순간낙하점을 계산하여 구성된 필터의 성능을 시험하였다.

• 비파괴검사학회지
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• 제37권2호
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• pp.91-98
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• 2017

Recently, composite materials have been mainly used in the main wings, ailerons, and fuselages of aircraft and rotor blades of helicopters. Composite materials used in rapid moving structures are subject to impact by hail, lightning, and bird strike. Such an impact can destroy fiber tissues in the composite materials as well as deform the composite materials, resulting in various problems such as weakened rigidity of the composite structure and penetration of water into tiny cracks. In this study, experiments were conducted using a 2 kW halogen lamp which is most frequently used as a light source, a 2 kW near-infrared lamp, which is used for heating to a high temperature, and a 6 kW xenon flash lamp which emits a large amount of energy for a moment. CFRP composite sandwich panels using Nomex honeycomb core were used as the specimens. Experiments were carried out under impact damages of 1, 4 and 8 J. It was found that the detection of defects was fast when the xenon flash lamp was used. The detection of damaged regions was excellent when the halogen lamp was used. Furthermore, the near-infrared lamp is an effective technology for showing the surface of a test object.

• 대한교통학회지
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• 제36권3호
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• pp.195-202
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• 2018

직주균형은 일정한 지역에서 직장과 주거가 일치하는 상태를 의미한다. 이 연구는 직주균형이 교통안전에 미치는 영향을 분석하는 데 그 목적이 있으며, 이를 위해 광역권별 사고 모형 개발에 중점을 둔다. 주요 연구결과는 다음과 같다. 첫째, 통계적으로 유의한 총 3개의 일반화선형모형이 개발된다. 모든 모형에서 직주균형 요소는 교통사고 발생에 유의미한 영향을 미치는 것으로 판단된다. 둘째, 공통변수 중 주택보급률은 사고율 감소, 그리고 경제활동인구비율 및 출근통행 도착량은 사고율 증가에 영향을 미치는 것으로 분석된다. 따라서 모든 지역에서는 직주 불균형을 완화하려는 노력이 필요할 것으로 평가된다. 셋째, 수도권에서는 직주비와 업무통행비, 그리고 부산 울산광역권에서는 교차통근비에 중점을 둔 교통안전정책이 요구된다.

• Steel and Composite Structures
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• 제27권4호
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• pp.417-426
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• 2018

This paper presents the seismic behaviors and restoring force model of ring beam joints of steel tube-reinforced concrete column structure under cyclic loading. First, the main failure mode, ultimate bearing capacity, stiffness degradation and energy dissipation capacity are studied. Then, the effects of concrete grade, steel grade, reinforcement ratio and radius-to-width ratios are discussed. Finally, the restoring force model is proposed. Results show that the ring beam joints of steel tube-reinforced concrete column structure performs good seismic performances. With concrete grade increasing, the ultimate bearing capacity and energy dissipation capacity increase, while the stiffness degradation rates increases slightly. When the radius-width ratio is 2, with reinforcement ratio increasing, the ultimate bearing capacity decreases. However, when the radius-to-width ratios are 3, with reinforcement ratio increasing, the ultimate bearing capacity increases. With radius-to-width ratios increasing, the ultimate bearing capacity decreases slightly and the stiffness degradation rate increases, but the energy dissipation capacity increases slightly.