• 한국지진공학회논문집
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• 제9권6호
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• pp.41-52
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• 2005

서울시 모델 구역의 건축물을 대상으로 가상 시나리오 지진에 의한 피해를 추정하였다. 다양한 주거 및 구조 특성을 대표할 수 있고 지반 증폭 효과를 고려할 수 있는 지역을 모델 구역으로 선정하였다. 모델 구역 내 건축물은 구조 형식에 따라 11 종류로 분류하였으며 HAZUS에서 제시한 값을 사용하여 역량 곡선(capacity curve)과 취약도 곡선(fragility curve)을 생성하였다. 가상 시나리오 지진의 지반 운동은 인공 지진 운동 생성 방법을 사용하여 생성하였으며 모델 구역을 표토층 두께에 따라 3개의 구역으로 나누고 지반응답해석을 수행하였다. 건축물의 피해 확률은 역량 스펙트럼 방법과 취약도 곡선을 사용하여 계산하였다. 최종적으로 GIS 데이터베이스를 활용하여 모델 구역 내 건축물의 전반적 피해 정도를 추정하였다.

• 한국가스학회지
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• 제15권2호
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• pp.69-74
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• 2011

화학공장에서 현실적인 사고피해 최소화 대책수립 방법을 제시하기 위하여 API-581 절차를 이용하여 누출 시 나리오를 설정하고, 정량적 원인분석이 가능한 한국형 위험기반검사(KS-RBI) 프로그램을 사용하여 사고 영향범위를 산출하였다. 그리고 위험성 평가를 실시하였다. 그 결과, 화학공장의 사고피해를 최소화하기 위해서는 4가지 누출공의 크기(소, 중, 대 및 파열)와 검출 및 차단 시스템의 등급에 따른 누출시간을 사용하고, 고장빈도에 의한 가중평균과 최악의 누출의 경우를 동시에 고려한 피해면적을 산출하여 비상조치계획을 수립하는 것이 바람직하였다.

• 화약ㆍ발파
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• 제40권4호
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• pp.27-34
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• 2022

탄소중립을 위한 온실가스 배출 감소를 위해 정부에서는 다양한 정책을 추진하고 있는데 그 핵심과제 중 하나가 수소경제 활성화 정책이다. 이 정책 중 하나로 정부는 기존 도시가스 배관에 수소를 혼입하는 추진안을 공식화하였고, 다가오는 2026년까지 20% 수소 혼입을 상용화하는 것을 목표로 하고 있다. 본 연구에서는 도시가스와 수소 혼입 상용화를 대비하여 이 두 가지 혼합가스의 누출사고 발생 시 피해 규모 및 영향범위를 정량적으로 예측하고자 한다. 정량적 피해예측 방식은 가상 시나리오에 따른 사고 발생 시 혼합가스의 누출량을 설정하여 TNT 당량 계산을 통해 피해 환산 거리를 산출하는 것이다.

• International Journal of Concrete Structures and Materials
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• 제10권2호
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• pp.237-247
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• 2016

Progressive collapse resistance of RC buildings can be analyzed by considering column loss scenarios. Using finite element analysis and a static test, the progressive collapse process of a RC frame under monotonic vertical displacement of a side column was investigated, simulating a column removal scenario. A single-story 1/3 scale RC frame that comprises two spans and two bays was tested and computed, and downward displacement of a side column was placed until failure. Our study offers insight into the failure modes and progressive collapse behavior of a RC frame. It has been noted that the damage of structural members (beams and slabs) occurs only in the bay where the removal side column is located. Greater catenary action and tensile membrane action are mobilized in the frame beams and slabs, respectively, at large deformations, but they mainly happen in the direction where the frame beams and slabs are laterally restrained. Based on the experimental and computational results, the mechanism of progressive collapse resistance of RC frames at different stages was discussed further. With large deformations, a simplified calculation method for catenary action and tensile membrane action is proposed.

• Nuclear Engineering and Technology
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• 제49권2호
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• pp.442-449
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• 2017

Risk management of the Fukushima Daiichi Nuclear Power Station decommissioning is a great challenge. In the present study, a risk management framework has been developed for the decommissioning work. It is applied to fuel assembly retrieval from Unit 3 spent fuel pool. Whole retrieval work is divided into three phases: preparation, retrieval, and transportation and storage. First of all, the end point has been established and the success path has been developed. Then, possible threats, which are internal/external and technical/societal/management, are identified and selected. "What can go wrong?" is a question about the failure scenario. The likelihoods and consequences for each scenario are roughly estimated. The whole decommissioning project will continue for several decades, i.e., long-term perspective is important. What should be emphasized is that we do not always have enough knowledge and experience of this kind. It is expected that the decommissioning can make steady and good progress in support of the proposed risk management framework. Thus, risk assessment and management are required, and the process needs to be updated in accordance with the most recent information and knowledge on the decommissioning works.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2008년도 정기학술발표대회 논문집
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• pp.149-154
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• 2008

국내 교량구조물의 대부분은 구조물, 자체에 의한 열화, 손상과 같은 물리적인 수명에 의하여 공용수명이 결정될 수 있어야 하지만, 이에 대한 연구가 미비하여 교량의 유지관리시 최적 유지관리 시나리오를 선정하는데 많은 어려움이 있다. 최적의 유지관리 시나리오를 선정하기 위해서는 부재별 열화에 의한 상태변화 및 유지관리를 위한 보수보강 효과를 고려한 상태/성능 분석이 반드시 요구되며, 본 연구에서 제안된 상태변화모델을 기반으로 기존에 구축된 DB 및 현재 운용중인 고속도로교량관리시스템(Highway Bridge Management System; HBMS)에 LCC 분석을 접목한 시스템개선의 효과 증대를 이를 수 있을 것으로 고려된다.

• Nuclear Engineering and Technology
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• 제45권4호
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• pp.469-476
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• 2013

In a postulated severe core damage accident in a PHWR, multiple failures of core cooling systems may lead to the collapse of pressure tubes and calandria tubes, which may ultimately relocate inside the calandria vessel forming a terminal debris bed. The debris bed, which may reach high temperatures due to the decay heat, is cooled by the moderator in the calandria. With time, the moderator is evaporated and after some time, a hot dry debris bed is formed. The debris bed transfers heat to the calandria vault water which acts as the ultimate heat sink. However, the questions remain: how long would the vault water be an ultimate heat sink, and what would be the failure mode of the calandria vessel if the heat sink capability of the reactor vault water is lost? In the present study, a numerical analysis is performed to evaluate the thermal loads and the stresses in the calandria vessel following the above accident scenario. The heat transfer from the molten corium pool to the surrounding is assumed to be by a combination of radiation, conduction, and convection from the calandria vessel wall to the vault water. From the temperature distribution in the vessel wall, the transient thermal loads have been evaluated. The strain rate and the vessel failure have been evaluated for the above scenario.

• Earthquakes and Structures
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• 제20권3호
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• pp.337-351
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• 2021

On September 12, 2016, the Gyeongju earthquake occurred in the south-eastern region of the Korean peninsula. The event was ranked as the largest magnitude earthquake (=5.8) since instrumental recording was started by the Korean Metrological Administration (KMA) in 1978. The objective of this study is to provide information obtained from the 2016 Gyeongju earthquake and to propose a procedure estimating seismic risk of a typical old RC building for past and potential earthquakes. Ground motions are simulated using the point source model at 4941 grid locations in the Korean peninsula that resulted from the Gyeongju earthquake and from potential future earthquakes with the same hypocenter considering different soil conditions. Nonlinear response history analyses are conducted for each grid location using a three-story gravity-designed reinforced concrete (RC) frame that most closely represents conventional old school and public buildings. Then, contour maps are constructed to present the seismic risk associated with this building for the Gyeongju earthquake and potential future scenario earthquakes. These contour maps can be useful in the development of a mitigation plan for potential earthquake damage to school and public buildings at all grid locations on the Korean peninsula.

• Nuclear Engineering and Technology
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• 제54권11호
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• pp.4030-4048
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• 2022

In this study, road transportation tests were conducted with surrogate fuel assemblies under normal conditions of transport to evaluate the vibration and shock load characteristics of spent nuclear fuel (SNF). The overall test data analysis was conducted based on the measured acceleration and strain data obtained from the speed bump, lane-change, deceleration, obstacle avoidance, and circular tests. Furthermore, representative shock response spectrums and power spectral densities of each test mode were acquired. Amplification or attenuation characteristics were investigated according to the load transfer path. The load attenuated significantly as it transferred from the trailer to the cask. By contrast, the load amplified as it transferred from the cask to the surrogate SNF assembly. The fuel loading location on the cask disk assembly did not exhibit a significant influence on the strain measured from the fuel rods. The principal strain was in the vertical direction, and relatively large strain values were obtained in spans with large spacing between spacer grids. The influence of the lateral location of fuel rods was also investigated. The fuel rods located at the side exhibited relatively large strain values than those located at the center. Based on the strain data obtained from the test results, a hypothetical road transportation scenario was established. A fatigue evaluation of the SNF rod was performed based on this scenario. The evaluation results indicate that no fatigue damage occurred on the fuel rods.

• 대기
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• 제22권1호
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• pp.47-55
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• 2012

The characteristics of flow and pollutant dispersion for fire scenarios in an urban area are numerically investigated. A computational fluid dynamics (CFD) model coupled to a mesoscale weather research and forecasting (WRF) model is used in this study. In order to more accurately represent the effect of topography and buildings, the geographic information system (GIS) data is used as an input data of the CFD model. Considering prevailing wind, firing time, and firing points, four fire scenarios are setup in April 2008 when fire events occurred most frequently in recent five years. It is shown that the building configuration mainly determines wind speed and direction in the urban area. The pollutant dispersion patterns are different for each fire scenario, because of the influence of the detailed flow. The pollutant concentration is high in the horse-shoe vortex and recirculation zones (caused by buildings) close to the fire point. It thus means that the potential damage areas are different for each fire scenario due to the different flow and dispersion patterns. These results suggest that the accurate understanding of the urban flow is important to assess the effect of the pollutant dispersion caused by fire in an urban area. The present study also demonstrates that CFD model can be useful for the assessment of urban environment.