• 제목/요약/키워드: System impact

검색결과 7,112건 처리시간 0.038초

A case study of protecting bridges against overheight vehicles

  • Aly, Aly Mousaad;Hoffmann, Marc A.
    • Steel and Composite Structures
    • /
    • 제43권2호
    • /
    • pp.165-183
    • /
    • 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.

Design of Repetitive Impact Tester and Mechanical Properties of Plastic Due to Cyclic Impacts (반복 충격장치 설계 및 반복충격에 의한 플라스틱 재료특성 연구)

  • Lee, Joon-Hyun;Lee, Sang-Pill;Lee, Jin-Kyung
    • Journal of Power System Engineering
    • /
    • 제21권5호
    • /
    • pp.29-34
    • /
    • 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.

Impact of solar storm on Navaids system (태양폭풍이 항행안전시설에 미치는 영향분석)

  • Jo, Jin-Ho;Park, Jae-Woo;Jeong, Cheol-Oh;Kim, Jae-Hoon;Kim, Gye-Hyeun;Park, Hyeung-Tak
    • Journal of the Korean Society for Aviation and Aeronautics
    • /
    • 제20권2호
    • /
    • pp.13-17
    • /
    • 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.

Study on Safety Evaluation Process for Hydrogen Storage System of Hydrogen Bus (수소버스 수소저장용기의 측면충돌 안전성 평가방법 연구)

  • Kyungjin, Kim;Jaeho, Shin;Kyeonghee, Han;Hyeon Min, Han;Jeong Min, In;Siwoo, Kim
    • Journal of Auto-vehicle Safety Association
    • /
    • 제14권4호
    • /
    • pp.113-119
    • /
    • 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.

Improvement of Review System on Sea Area Utilization-Impact by Marine Environmental Management Law (해양환경관리법상 해역이용영향 검토기관의 발전방향)

  • Lee, Dae-In;Eom, Ki-Hyuk;Kim, Gui-Young;Jang, Ju-Hyoung
    • Journal of the Korean Society for Marine Environment & Energy
    • /
    • 제11권1호
    • /
    • pp.55-62
    • /
    • 2008
  • This study investigated the status and problems of marine-related environmental impact assessment and a utilization-consultation system in Korea and suggested improvement of the review organization. Also, it conducted SWOT analysis based on evaluation of functions, roles and performance of the marine environmental impact assessment center and proposed development strategies of the center through introduction of expert opinions and advanced systems. The performance statement-review by the center in 2007 included 358 cases in total; 165 (46.1%) for consultation on utilization of sea area, 104 for environmental impact assessment (29.0%), and 89 (24.9%) for prior environmental review. The consultation on utilization of sea area can be divided into that for public water surface-use (41%) and reclamation (32%), and sea aggregate extraction process (21%). Although bad impacts on marine environment are reducing under the current system, there are some limits and problems to supplement it in terms of content, system and operation. Review system on sea area utilization-impact(marine environmental impact assessment center) by marine environmental management law needs to obtain expertise, fairness and efficiency and, to do so, have operational supports and institutional improvement to maximize its own functions and roles. At the same time, it is necessary for the center to establish identity and the status as a professional review organization by setting active development strategies inside the center. Finally, it should strengthen an consultation system of marine environmental impact assessment led by the related ministry to achieve effective coastal management.

  • PDF

Hypervelocity Impact Analyses Considering Various Impact Conditions for Space Structures with Different Thicknesses (다양한 두께의 우주 구조물에 대한 다양한 충돌 조건의 초고속 충돌 해석 연구)

  • Won-Hee Ryu;Ji-Woo Choi;Hyo-Seok Yang;Hyun-Cheol Shin;Chang-Hoon Sim;Jae-Sang Park
    • Journal of Aerospace System Engineering
    • /
    • 제17권4호
    • /
    • pp.43-57
    • /
    • 2023
  • The hypervelocity impact simulations of space objects and structures are performed using LS-DYNA. Space objects with spherical, conical, and hollow cylindrical shapes are modeled using the Smoothed Particle Hydrodynamics (SPH). The direct and indirect impact zones of a space structure are modeled using the SPH and finite element methods, respectively. The Johnson-Cook material model and Mie-Grüneisen Equation of State are used to represent the nonlinear behavior of metallic materials in hypervelocity impact. In the hypervelocity impact simulations, various impact conditions are considered, such as the shape of the space object, the thickness of the space structure, the impact angle, and the impact velocity. The shapes of debris clouds are quantitatively classified based on the geometric parameters. Conical space objects provide the worst debris clouds for all impact conditions.

A Study on Improvement of Floor Impact Noise Section in the Housing Performance Grading Indication System (주택성능등급제도내 바닥충격음 개선방안 연구)

  • Go, Jong-Chul
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 한국소음진동공학회 2008년도 추계학술대회논문집
    • /
    • pp.593-594
    • /
    • 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.

  • PDF

A Study on the Development of High Performance Floor Impact Noise Insulation System (고성능 바닥충격음 차단구조 개발에 관한 연구)

  • Jang, Jae-Hee
    • KIEAE Journal
    • /
    • 제7권2호
    • /
    • pp.71-76
    • /
    • 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.

A Study on Environmental Impact Assessment on the Area Expansion of Limestone Mining with regard to Cumulative Impact Assessment (누적영향평가 측면에서 환경영향평가제도의 문제점과 개선방안 연구 - 석회석광산 채굴규모 확장을 대상으로 -)

  • Kim, Cho;Yeon, Ik-Jun;Jung, Ju-Yong;Lee, Sang-Woo
    • Journal of Environmental Impact Assessment
    • /
    • 제23권1호
    • /
    • pp.1-9
    • /
    • 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.

Use of Environmental Geospatial Information to Support Environmental Impact Assessment Follow-Up Management (환경영향평가의 사후관리 지원을 위한 환경공간정보 활용 방안)

  • Cho, Namwook;Maeng, Jun Ho;Lee, Moung Jin
    • Korean Journal of Remote Sensing
    • /
    • 제33권5_3호
    • /
    • pp.799-807
    • /
    • 2017
  • Environmental impact assessment is a regulation that is implemented to reduce harmful environmental impacts of development projects. However, The environmental value is difficult to quantify and the uncertainty, There is a problem of objectivity and reliability of the system is consistently pointed out. Therefore, the necessity of the data-based environmental impact assessment system is gradually increasing. Especially, environmental impact assessment is highly applicable to environmental spatial information because it contains about the development of a particular area. Also with the introduction of EIA Follow-up management system, there is a demand for a system for providing and utilizing environmental information in a time series. This study derives the necessity of information provision system and analyz existing environmental information utilization system based on the institutional characteristics of environmental impact assessment. And suggest ways to provide environmental spatial information to find policy implications for improving the limit of environmental impact assessment system.