• Steel and Composite Structures
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• 제43권2호
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• pp.165-183
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• 2022

Most transportation departments have recognized and developed procedures to address the ever-increasing weights of trucks traveling on bridges in a service today. Transportation agencies also recognize the issues with overheight vehicles' collisions with bridges, but few stakeholders have definitive countermeasures. Bridges are becoming more vulnerable to collisions from overheight vehicles. The exact response under lateral impact force is difficult to predict. In this paper, nonlinear impact analysis shows that the degree of deformation recorded through the modeling of the unprotected vehicle-girder model provides realistic results compared to the observation from the US-61 bridge overheight vehicle impact. The predicted displacements are 0.229 m, 0.161 m, and 0.271 m in the girder bottom flange (lateral), bottom flange (vertical), and web (lateral) deformations, respectively, due to a truck traveling at 112.65 km/h. With such large deformations, the integrity of an impacted bridge becomes jeopardized, which in most cases requires closing the bridge for safety reasons and a need for rehabilitation. We proposed different sacrificial cushion systems to dissipate the energy of an overheight vehicle impact. The goal was to design and tune a suitable energy absorbing system that can protect the bridge and possibly reduce stresses in the overheight vehicle, minimizing the consequences of an impact. A material representing a Sorbothane high impact rubber was chosen and modeled in ANSYS. Out of three sacrificial schemes, a sandwich system is the best in protecting both the bridge and the overheight vehicle. The mitigation system reduced the lateral deflection in the bottom flange by 89%. The system decreased the stresses in the bridge girder and the top portion of the vehicle by 82% and 25%, respectively. The results reveal the capability of the proposed sacrificial system as an effective mitigation system.

• 동력기계공학회지
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• 제21권5호
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• pp.29-34
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• 2017

Many household appliances, including vacuum cleaners, are being subjected to various of impact damages, and made of plastic. However, researches on the damage of appliances materials by repetitive impacts have been rarely conducted. the mechanical stress exerted upon impact-modified polycarbonate (PC) has a great influence not only on the quality of the product but also on the life span. The purpose of this research was to quantify the effects of repetitive impact on the polycarbonate. Second, it was to design the repetitive impact tester for controlling the impact energy. The mechanical properties of tensile strength, yielding stress and strain on the specimens subjected to cyclic impacts were discussed. Tensile strength was sharply declined at the beginning of the impact cycles, while the strain gradually decreased during impact cycles.

• 한국항공운항학회지
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• 제20권2호
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• pp.13-17
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• 2012

The solar storm generated by solar activity can be impact on earth in various area. If solar storm impact on Navaids system, it will be a serious problem for aviation and human safety. The impact analysis of solar strom on Navaids system are performed in three area, ILS, GPS navigation and radio communication for aviation. Analysis result show that Instrument Landing System(LLZ, GP, MB) and Navaids system(VOR, DME, Radar) are not impacted by the solar storm, but GPS system is impacted by solar storm. Also analysis result show that VHF/UHF radio system are not impacted by solar storm, but HF radio system is impacted by solar storm.

• 자동차안전학회지
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• 제14권4호
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• pp.113-119
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• 2022

The structural safety of hydrogen buses is being evaluated for the successful introduction of hydrogen buses. The crash test methodology, for example, side impact test procedure is being discussed for hydrogen bus structure safety with a compressed hydrogen storage system located under the bus floor. Thus this study describes a new experiment method for side impact test with compressed hydrogen storage system independently based on finite element analysis instead of side impact test using full hydrogen bus. A side crash procedure of conceptual compressed hydrogen storage structure was investigated and impact simulations were performed. The finite element models of hydrogen bus, simplified structures, fuel tank system and side impact moving barrier were set up and simulation results reported model performance and result comparison of three different simplified models. Computational results and research discussion proposed the fundamental test framework for safety assessment of the compressed hydrogen storage system.

• 한국해양환경ㆍ에너지학회지
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• 제11권1호
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• pp.55-62
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• 2008

본 논문에서는 현재 시행되고 있는 우리나라의 해양관련 환경영향평가와 협의제도의 현황과 문제점을 파악하여 관련 제도의 개선방향을 연구하였다. 또한 해양환경관리법상 해역이용영향 검토기관(이하 검토기관이라 함)의 기능과 역할 및 수행실적을 조사하여 SWOT 분석을 실시하였고, 나아가서 운영상 개선사항과 발전방향을 제안하였다. 2007년 검토기관에서 수행한 실적은 총 358건으로, 해역이용협의서가 165건(46.1%)으로 가장 많았고, 환경영향평가서 104건(29.0%), 그리고 사전환경성검토서가 89건(24.9%)이었다. 해역이용협의의 내용별로는 공유수면점 사용, 공유 수면매립과 바다골재채취 관련이 각각 41%, 32%와 21%를 차지하였다. 그러나 이러한 제도시행으로 해역이용개발 행위가 해양환경에 미치는 악영향을 최소화하고 있지만, 사전예기능으로서의 한계와 여러 가지 내용적 그리고 제도상운영상 측면에서 보완하고 개선해야 할 문제점이 지적되었다. 검토기관의 전문성, 공정성과 효율성을 확보하는 것이 매우 중요하고, 이를 위해서는 고유 기능과 역할을 극대화시킬 수 있는 제도적 개선과 운영상 지원이 필요하며, 동시에 자체적으로 적극적인 발전전략을 수립함으로써 전문적인 검토기관으로서의 정체성 확보와 위상을 정립시켜야 할 것이다. 연안관리의 실효성을 확보하기 위해서는 효율적인 해역이용협의제도를 지향하고, 주무부처의 해양환경관리에 대한 구동력과 능동성을 강화 확립해 나가야 할 것이다.

• 항공우주시스템공학회지
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• 제17권4호
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• pp.43-57
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• 2023

우주 물체 및 우주 구조물의 초고속 충돌 시뮬레이션을 LS-DYNA를 사용하여 수행하였다. 구형, 원뿔형, 및 속이 빈 원통형의 다양한 형상의 우주 물체는 SPH(Smoothed Particle Hydrodynamics)를 사용하여 모델링하였다. 다양한 두께의 우주 구조물은 직접 충돌 영역과 간접 충돌 영역으로 나누어, 각각 SPH 및 유한 요소를 사용하여 나타내었다. 초고속 충돌에서 금속 재료의 비선형 거동을 나타내기 위하여 Johnson-cook 재료 모델과 Mie-Grüneisen 상태 방정식을 사용하였다. 우주 물체의 형상, 우주 구조물의 두께, 충돌 각도, 및 충돌 속도의 다양한 충돌 조건을 고려하였다. 파편운은 우주 물체와 우주 구조의 초고속 충돌로 인해 발생되며, 발생된 파편운의 형상을 정량적으로 분석하였다. 본 연구의 모든 충돌 조건에서, 원뿔 형상의 우주 물체로 인한 파편운이 가장 위험한 형상임을 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.593-594
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• 2008

The purpose of this study is to review and to suggest improvement concerning floor impact noise section of the housing performance grading indication system. After a result, the main improvement is to resolve the discrepancies in the rules or regulations such as design specification(standard floor system) or design performance(accredited floor system) and as-built performance like 58 dB.

• KIEAE Journal
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• 제7권2호
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• pp.71-76
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• 2007

For the many years the children's running noise has caused perpetual frictions between neighbors in apartment houses. For this reason the government established a regulation to reduce the floor impact noise, as a result almost all apartment houses have been enforced to use the floor structure with 210mm thickness concrete slab and 120mm thickness of floor heating system since July 2005. If do not want to apply this kind of system, a system which obtain the certification from the institution appointed by government must be applied. In this reason a lot of construction material companies and construction companies have been trying to develop the system with 180mm thickness concrete slab for the purpose of reducing the cost. To develop the optimized floor system, actual size test building were constructed and the materials related with reducing floor impact noise were composited and tested in the test building. Through this procedure the most effective system was found.

• 환경영향평가
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• 제23권1호
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• pp.1-9
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• 2014

This study, focusing on the area expansion of limestone mines, identifies the problems of Environmental Impact Assessment(EIA) and what impact the current problems exert on another mines developing process. The legal relations analysis reveals that the Management of Mountainous Districts Act and other related laws effect on EIA process, especially the case of area expansion of limestone mines excluded from EIA. However, these problems can create mismatch with the policy goal of EIA system and have a negative impact on the environment in the future. A series of indepth interviews with managers in related agencies found that those agencies have been unaware of the seriousness of the problem. Without any strategy, negative result made by development activities would get more serious and sustainable development may not be possible at all. In order to solve these problems, government should modify the current interdependent legal provision and create the incentive structure to participate actively related agency in the EIA system.

• 대한원격탐사학회지
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• 제33권5_3호
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• pp.799-807
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• 2017

환경영향평가는 개발사업의 해로운 환경영향 감소를 위해 시행되는 규제적 성격의 제도이다. 그러나 환경가치는 계량화가 어렵고 불확실성이 따르기 때문에 제도 운영의 객관성 및 신뢰성 저하 문제가 지속적으로 지적되어 온 실정이다. 따라서 데이터 기반 환경영향평가제도의 필요성이 점차 높아지고 있는데, 특히 환경영향평가는 특정 지역의 개발에 대한 내용을 담기 때문에 공간정보의 비중이 높아 환경공간정보의 활용 가능성이 높은 분야이다. 또한 사후환경관리제도의 도입에 따라 환경정보의 시계열적 제공 및 활용체계가 요구되고 있다. 본 연구에서는 환경영향평가의 제도적 특징을 통해 정보제공체계의 필요성을 도출하고 기존 환경정보 활용체계를 분석하였다. 그리고 이를 토대로 공신력 있는 환경공간정보 제공방안을 제시하여 환경영향평가제도의 한계점 개선을 위한 정책적 함의를 찾고자 하였다.