• 한국농공학회논문집
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• 제66권1호
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• pp.49-66
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• 2024

Extreme rainfall will become intense due to climate change, increasing inundation risk to agricultural land. Hydrological and hydraulic simulations for the entire watershed were conducted to analyze the impact of climate change. Rainfall data was collected based on past weather observation and SSP (Shared Socio-economic Pathway)5-8.5 climate change scenarios. Simulation for flood volume, reservoir operation, river level, and inundation of agricultural land was conducted through K-HAS (KRC Hydraulics & Hydrology Analysis System) and HEC-RAS (Hydrologic Engineering Center - River Analysis System). Various scenarios were selected, encompassing different periods of rainfall data, including the observed period (1973-2022), near-term future (2021-2050), mid-term future (2051-2080), and long-term future (2081-2100), in addition to probabilistic precipitation events with return periods of 20 years and 100 years. The inundation area of the Aho-Buin district was visualized through GIS (Geographic Information System) based on the results of the flooding analysis. The probabilistic precipitation of climate change scenarios was calculated higher than that of past observations, which affected the increase in reservoir inflow, river level, inundation time, and inundation area. The inundation area and inundation time were higher in the 100-year frequency. Inundation risk was high in the order of long-term future, near-term future, mid-term future, and observed period. It was also shown that the Aho and Buin districts were vulnerable to inundation. These results are expected to be used as fundamental data for assessing the risk of flooding for agricultural land and downstream watersheds under climate change, guiding drainage improvement projects, and making flood risk maps.

• 한국응용과학기술학회지
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• 제35권3호
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• pp.606-611
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• 2018

산업현장과 열병합발전 등 다양한 장소에 사용되는 도시가스는 산업안전보건법 정의에 따라 인화성 가스에 해당되며 한국산업표준 KS C IEC에 의해 가스 폭발위험장소가 설정되어 안전하게 관리가 되어야 한다. 본 연구에서는 일반 화학공장에 적용되는 KS C IEC 표준을 저압 도시가스 사용설비 폭발위험성 예측에 합리적으로 적용하기 위해누출공 크기, 환기 등급, 환기 유효성 등의 주요 변수를 도입하였다.CFD 시뮬레이션 적용의 타당성을 평가하기 위해 전산유체역학 (CFD) 시뮬레이션, 가스누출실험, KS C IEC 표준 계산 통해 얻어진 폭발하한계가상 체적을 이용하여 네 가지 다른 조건에서 폭발 위험성을 평가하였다.

• Environmental Analysis Health and Toxicology
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• 제14권4호
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• pp.203-216
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• 1999

This paper describes a set of multi-pathway models for estimating health risk to lead. The models link concentrations of an environmental contaminant (lead) in air, water and food to human exposure through inhalation, ingestion, and dietary routes. Exposure is used as the foundation for predicting risk of health detriment within the population. The process of estimating exposure using often limited data and extrapolating to a large diverse population requires many assumption, inferences, and simplification. This paper is divided into four section. The first section provides lead contaminant levels on obtaining environmental concentration of air, tap water, and foods. The second section provides a discussion of exposure parameters and uncertainty associated predicting human health risk of contaminants. The third and fourth section illustrate lifetime average daily exposure (LADE) and excess cancer risk (ECR) based on exposure parameters. The relationship between concentration of lead in an environmental medium and human exposure is determined with pathway exposure factors (PEFs). The calculation of LADE and ECR is carried out using Monte-Carlo simulation with probability density function of exposure parameters. Examination of the result reveals that, for lead exposure, ingestion (food) is the dominant route of exposure rather than inhalation (air), and ingestion (tap eater).

• Journal of Positioning, Navigation, and Timing
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• 제9권3호
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• pp.285-292
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• 2020

This paper introduces a new computational efficient Dilution of Precision (DOP)-based landmark exclusion method while ensuring the safety of the LiDAR-based navigation system that uses an innovation-based Nearest-Neighbor (NN) Data Association (DA) process. The NN DA process finds a correct landmark association hypothesis among all potential landmark permutations using Kalman filter innovation vectors. This makes the computational load increases exponentially as the number of landmarks increases. In this paper, we thus exclude landmarks by introducing DOP that quantifies the geometric distribution of landmarks as a way to minimize the loss of integrity performance that can occur by reducing landmarks. The number of landmarks to be excluded is set as the maximum number that can satisfy the integrity risk requirement. For the verification of the method, we developed a simulator that can analyze integrity risk according to the landmark number and its geometric distribution. Based on the simulation, we analyzed the relationship between DOP and integrity risk of the DA process by excluding each landmark. The results showed a tendency to minimize the loss of integrity performance when excluding landmarks with poor DOP. The developed method opens the possibility of assuring the safety risk of the Lidar-based navigation system in real-time applications by reducing a substantial amount of computational load.

• 한국화재소방학회논문지
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• 제29권2호
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• pp.8-12
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• 2015

성능위주소방설계 초기단계로서 피난안전성평가에 있어서 Available safe egress time (ASET)과 Required safe egress time (RSET)를 계산하여 단순비교하고 있다. 본 논문에서는 FDS를 이용하여 열, 연기, 독성가스 등에 대한 위험정보값을 추출하였다. 또한 피난시뮬레이션 프로그램인 Artisoc를 이용하여 FDS에서 추출한 위험정보값을 적용하였다. 건축물의 구조는 가로 60 m, 세로 65 m로 구성하였으며, 출입구는 2곳에 설치하였으며 재실자는 50명을 랜덤하게 배치하였다. 시뮬레이션은 case1~case20 까지 총 20회에 걸쳐 진행하여, 피난 경로별 위치에 따른 재실자의 위험도를 분석하였다. 이를 통해 위험정보값을 적용하여 기존의 단순비교 하던 피난안전성평가의 신뢰도를 높이기 위한 위험정보값 전달기반의 평가기법을 제시하였다.

• 한국지능시스템학회논문지
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• 제21권1호
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• pp.112-119
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• 2011

본 연구는 주변 환경정보와 장애물정보, 위치정보를 이용하여 무인잠수정의 운항 환경에 존재하는 다양한 장애물들에 대한 충돌위험도를 산출하는 시스템을 제안한다. 충돌위험도는 퍼지추론을 사용하여 산출하며, TCPA, DCPA, 거리를 인자로 사용하게 된다. 또한 삼차원환경에서 TCPA와 DCPA를 획득하는 방법을 제안한다. 충돌위험도는 충돌회피시스템에 제공되며, 시뮬레이션을 통하여 그 경제성과 안전성에서의 효율성을 보인다.

• 한국도로학회논문집
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• 제16권1호
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• pp.91-98
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• 2014

PURPOSES : Recently, there are increasing bicycle accidents along with increasing bicycles users. Bicycle accidents occurred frequently by perpendicular collision form at intersection inner. In order to improve safety of bicycle, drivers need to be aware of bicycles on the road and intersection geometric designs need to be designed to reduce risk associated with collisions between bicycles and car. This study aims to review the location of bicycle crossing in the viewpoint of bicycle safety. METHODS : Four types of bicycle crossing by curve radius and driver's check around the behavior are set to simulate the risk of collisions between bicycles and car turning right. Simulation using fortran programming are conducted on total 60 cases. RESULTS : Bicycle crossing located behind of crosswalk is lower the risk of collisions with car in all cases. In addition to the larger curve radius of pavement edge at intersection and the more pay attention to the rear by the turn head to the right is too low the risk of collisions with car. CONCLUSIONS : It is show that the location of bicycle crossing is safer behind than in front of crosswalk in the viewpoint of bicycle safety.

• Communications for Statistical Applications and Methods
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• 제28권1호
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• pp.59-79
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• 2021

Value at Risk (VaR) is one of the most common risk management tools in finance. Since a portfolio of several assets, rather than one asset portfolio, is advantageous in the risk diversification for investment, VaR for a portfolio of two or more assets is often used. In such cases, multivariate distributions of asset returns are considered to calculate VaR of the corresponding portfolio. Copulas are one way of generating a multivariate distribution by identifying the dependence structure of asset returns while allowing many different marginal distributions. However, they are used mainly for bivariate distributions and are not widely used in modeling joint distributions for many variables in finance. In this study, we would like to examine the performance of various copulas for high dimensional data and several different dependence structures. This paper compares copulas such as elliptical, vine, and hierarchical copulas in computing the VaR of portfolios to find appropriate copula functions in various dependence structures among asset return distributions. In the simulation studies under various dependence structures and real data analysis, the hierarchical Clayton copula shows the best performance in the VaR calculation using four assets. For marginal distributions of single asset returns, normal inverse Gaussian distribution was used to model asset return distributions, which are generally high-peaked and heavy-tailed.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 추계학술발표회
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• pp.173-173
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• 2017

• 한국항해항만학회지
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• 제46권4호
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• pp.359-366
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• 2022

FFA는 1990년대 초반 이후 시장위험의 헤징을 위한 유효한 수단으로 대두되었지만 베이시스위험으로 헤징의 효과성이 크게 저해될 수 있다는 점과 현금흐름의 불일치 등이 활성화의 장애요인으로 지적된다. 본 연구는 FFA의 헤징효과에 영향을 미치는 베이시스위험에 대하여 분석하고 이를 축소하기 위한 대안을 제시한다. 베이시스위험은 시점불일치, 항로불일치, 선박크기불일치 및 저유동성 베이시스위험으로 구분할 수 있는데 그 중 시점불일치 베이시스위험은 특정일 기준으로 지급되는 실물 선박의 용선료와 일정기간의 평균으로 정산되는 FFA의 정산가격과의 차이에 의해서 발생하는 것으로 헤징오류 원인 중 가장 큰 차이를 발생시키는 것이다. 이 연구에서는 성약일 기준 용선료를 15일 간격 이동평균 용선료로 변경한다는 대안을 제시하고 이의 차이와 운임선도거래 정산가격과의 차이를 도출하는 것을 역사적 시뮬레이션을 통하여 실증분석하였다. 연구결과 시점불일치 베이시스위험은 15일 이동평균을 적용함으로써 현저히 축소시킬 수 있는 것이 확인되었다. 이 연구는 용선료 지급기준 변경을 통해 베이시스위험을 축소하고 궁극적으로 운임선도거래를 활성화시킬 수 있는 가능성을 제시함으로써 해운실무에 유의미한 시사점을 제시한다.