• 시스템엔지니어링학술지
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• 제16권2호
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• pp.97-109
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• 2020

On March 11, 2011, an earthquake followed by a tsunami caused an extended station blackout (SBO) at the Fukushima Dai-ichi NPP Units. The accident was initiated by a total loss of both onsite and offsite electrical power resulting in the loss of the ultimate heat sink for several days, and a consequent core melt in some units where proper mitigation strategies could not be implemented in a timely fashion. To enhance the plant's coping capability, the Diverse and Flexible Strategies (FLEX) were proposed to append the Emergency Operation Procedures (EOPs) by relying on portable equipment as an additional line of defense. To assess the success window of FLEX strategies, all sources of uncertainties need to be considered, using a physics-based model or system code. This necessitates conducting a large number of simulations to reflect all potential variations in initial, boundary, and design conditions as well as thermophysical properties, empirical models, and scenario uncertainties. Alternatively, data-driven models may provide a fast tool to predict the success window of FLEX strategies given the underlying uncertainties. This paper explores the applicability of Artificial Intelligence (AI) to identify the success window of FLEX strategy for extended SBO. The developed model can be trained and validated using data produced by the lumped parameter thermal-hydraulic code, MARS-KS, as best estimate system code loosely coupled with Dakota for uncertainty quantification. A Systems Engineering (SE) approach is used to plan and manage the process of using AI to predict the success window of FLEX strategies under extended SBO conditions.

• Asian-Australasian Journal of Animal Sciences
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• 제20권8호
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• pp.1305-1318
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• 2007

On a global scale agriculture and in particular enteric fermentation in ruminants is reported to produce about one fourth (21 to 25%) of the total anthropogenic emissions of methane ($CH_4$). Methane is produced during the anaerobic fermentation of hydrolyzed dietary carbohydrates in the rumen and represents an energy loss to the host besides contributing to emissions of greenhouse gases into the environment. However, there appears to be uncertainty in the $CH_4$ estimation from livestock due to the limited availability of data to document the variability at the farm level and also due to the significant impact of diet on the enteric $CH_4$ production. The methane mitigation strategies require robust prediction of emissions from rumen. There are many methods available which would be suitable for measuring $CH_4$ produced from the various stages of animal production. However, several factors need to be considered in order to select the most appropriate technique like the cost, level of accuracy required and the scale and design of the experiments to be undertaken. Selection of any technique depends on the accuracy as each one has its advantages and disadvantages. Screening of mitigation strategies may be evaluated using individual animal before large-scale trials on groups of animals are carried out. In this review various methods for the estimation of methane production from ruminants as well as for the determination of methane production potential of ruminant feeds are discussed. The advantages and disadvantages of the methods starting from respiration chamber, ventilated hood, facemask, sulphur hexafluoride ($SF_6$) tracer technique, prediction equations and meteorological methods to in vitro methods are detailed.

• 한국재난관리표준학회지
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• 제2권3호
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• pp.25-30
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• 2009

기후변화 동에 따른 세계 재해의 발생빈도 및 규모가 증가함에 따라 UN 등 국제사회에서는 피해지역에 대한 재해 복구 지원과 원조를 확대해 나가고 있다. 또한 저개발국가의 재해경감을 위한 다양한 지원프로그램을 추진하고 있어, 우리나라에서도 KOICA 프로그램의 활성화 및 체계적인 국제지원체계구축의 필요성이 대두되고 있다. 본 연구는 국제적 재해에 대한 UN 국제기구, 선진국가의 체계를 분석하여 우리나라가 효과적으로 지원할 수 있는 체계를 제안함으로써 국제사회의 재해경감 노력에 참여하고 국제 사회에서의 국가위상을 제고하고자 하였다.

• Nuclear Engineering and Technology
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• 제46권5호
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• pp.595-604
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• 2014

SILER (Seismic-Initiated event risk mitigation in LEad-cooled Reactors) is a Collaborative Project, partially funded by the European Commission in the $7^{th}$ Framework Programme, aimed at studying the risk associated to seismic-initiated events in Generation IV Heavy Liquid Metal reactors, and developing adequate protection measures. The project started in October 2011, and will run for a duration of three years. The attention of SILER is focused on the evaluation of the effects of earthquakes, with particular regards to beyond-design seismic events, and to the identification of mitigation strategies, acting both on structures and components design. Special efforts are devoted to the development of seismic isolation devices and related interface components. Two reference designs, at the state of development available at the beginning of the project and coming from the $6^{th}$ Framework Programme, have been considered: ELSY (European Lead Fast Reactor) for the Lead Fast Reactors (LFR), and MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) for the Accelerator-Driven Systems (ADS). This paper describes the main activities and results obtained so far, paying particular attention to the development of seismic isolators, and the interface components which must be installed between the isolated reactor building and the non-isolated parts of the plant, such as the pipe expansion joints and the joint-cover of the seismic gap.

• 대한안전경영과학회지
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• 제21권4호
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• pp.7-15
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• 2019

This paper proposes the FMEA-based model to avoid backdoor transactions when purchasers select suppliers for products and services. In the model, backdoor transactions consist of two categories: backdoor selling and maverick buying. Both of which influence negative effects on cost savings due to not only uncompetitive advantage but also unusable purchasing leverage by unethical and misbehavior of purchase requestors. For the risk evaluation based on FMEA, three and five risk types of backdoor selling and maverick buying are identified respectively. Current risk priority numbers(RPN) based on those risk types are calculated by three categories: occurrence, detection and severity. Six risk mitigation strategies and fourteen mitigation tactics are identified to improve current RPN. In order to validate the model, questionnaires are collected from fifteen companies and statistically analyzed. The analysis result shows that the model reduces backdoor transaction risks and has no differences in reduction of backdoor transaction risks regardless of the type of purchasing organization units and existence of purchasing procedures in the organization.

• 한국환경과학회지
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• 제29권11호
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• pp.1033-1054
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• 2020

Repeated use of land is depleting future resources and causing many ecological problems, prompting the need for a natural resource policy focusing on effective conservation. This study aims to identify methods based on international cases useful for introducing sustainable conservation of domestic natural resources. Currently, South Korea has developed and enforced many management and evaluation strategies for natural resources. However, due to limitations on policies and management, they show signs of strain. Therefore, this study compares and analyzes international conservation policies for nature and scenery, such as Germany's impact mitigation regulation, the USA's HEA (habitat equivalency analysis) and REA (resource equivalency analysis) policies, and Japan's three laws for landscape and greenery, to achieve the following three goals: first, find natural resources suitable for South Korea and define them. Second, plan goals for mitigation of total natural resources and build a basis for them. Third, establish effective complete plans for evaluating the total amount of natural resources.

• 한국방재학회 논문집
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• 제11권2호
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• pp.53-57
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• 2011

최근 해양 레포츠와 관광의 활성화로 연안역에서의 안전사고 위험은 더욱 증가하고 있다. 그러나 연안역 안전사고를 방지하기 위한 대책이 안전사고의 증가속도에 적절하게 대응하지 못하고 있다. 연안역의 환경은 육역과 해역의 특성이 혼재된 복합 환경 조건이므로 연안역 안전사고 대책방안 수립 시에는 육역과 해역의 특성이 적절히 고려되어야 한다. 본 논문에서는 현장실태조사를 통해 연안역 안전에 대한 현 문제점을 분석하였으며 연안역 안전의 개선방향을 근거로 연안역 안전기준 정립방향을 제안하였다.

• 한국해양공학회지
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• 제37권4호
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• pp.158-163
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• 2023

Objects adrift can cause considerable damage to coastal infrastructure and property during tsunami and storm surge events. Despite the potential for harm, the drifting behavior of these objects remains poorly understood, thereby hindering effective prediction and mitigation of collision damage. To address this gap, this study employed a motion analysis program to track a drifting container's location using images from an existing laboratory experiment. The container's trajectory and velocity were calculated based on the positions of five markers strategically placed at its four corners and center. Our findings indicate that the container's maximum drift velocity and distance are directly influenced by the scale of the solitary wave and inversely related to the container's weight. Specifically, heavier containers are less likely to be displaced by solitary waves, while larger waves can damage coastal structures more. This study offers new insights into container drift behavior induced by solitary waves, with implications for enhancing coastal infrastructure design and devising mitigation strategies to minimize the risk of collision damage.

• Journal of Contemporary Eastern Asia
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• 제18권2호
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• pp.90-117
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• 2019

How is science advice integrated in environmental policymaking? This is an increasingly pertinent question that is being raised since the nuclear catastrophe of Fukushima, Japan, in 2011. Global re-evaluation of energy policies and climate mitigation measures include discussions on how to better integrate science advice in policymaking, and at the same time keeping science independent from political influence. This paper addressed the policy discourse of setting up a national CO2 reduction target in Japanese policymaking between 2009 and 2012. The target proposed by the former DPJ government was turned down, and Japan lacked a clear strategy for long-term climate mitigation. The analysis provides explanations from a quantitative actor-network perspective. Centrality measures from social network analysis for policy actors in an environmental policy network of Japan were calculated to identify those actors that control the discourse. Data used for analysis comes from the Global Environmental Policy Actor Network 2 (GEPON 2) survey conducted in Japan (2012-13). Science advice in Japan was kept independent from political influence and was mostly excluded from policymaking. One of the two largest discourse coalitions in the environmental policy network promoted a higher CO2 reduction target for international negotiations but favored lowering the target after a new international agreement would have been set. This may explain why Japan struggled to commit to long-term mitigation strategies. Applying social network analysis to quantitatively calculate discourse coalitions was a feasible methodology for investigating "discursive power." But limited in discussing the "practice" (e.g. meetings, telephone, or email conversations) among the actors in discourse coalitions.

• 한국방재학회 논문집
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• 제9권2호
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• pp.31-37
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• 2009

우리나라는 매년 풍수해에 의한 피해가 증가하고 있으며, 대부분의 피해가 하천, 도로시설물을 중심으로 주로 일어나고 있다. 이들 피해에 따른 국가복구지원의 문제점은 매년 많은 금액의 피해 복구비가 투입되었음에도 불구하고, 개선복구 보다는 원상복구 위주의 복구비 지원으로 반복적 피해가 발생하고 있다는 사실이다. 이러한 재난의 비효율적 반복피해를 예방하기 위해서는 자연재난으로 인한 피해의 원인을 보다 정확히 진단하고 항구적인 방어대책의 마련을 위한 보다 구체적인 기준이 필요하다. 본 연구에서는 최근 국내에서 발생하고 있는 풍수해에 대한 전반적인 실태조사를 통하여 피해현상의 유형별 구분과 분석을 각각의 피해에 대한 복구방법이나 대책방법으로 각각 체계적으로 다르게 분류하고 보다 선진화된 예방적 복구 개념을 도입하기 위하여 피해 유형별로 새롭게 정리하였다. 이를 통하여 피해유형에 따른 피해분류 및 피해사례를 보다 체계적으로 수립, 계획할 수 있는 유형화 도감 및 평가방법을 국내외 수많은 기 선행 개선복구 사례를 토대로 분류, 개발하였다.