• 한국산업융합학회 논문집
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• 제23권4_2호
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• pp.569-581
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• 2020

Since the dehydration packages of offshore plant deal directly with oil & gas, there is a great risk of fire and explosion during operation. Therefore, this study performed risk assessment through HAZard & OPerability (HAZOP) for solid desiccant dehydration package that can remove water component of natural gas in offshore floating liquefied natural gas (LNG) production facilities below 0.1 ppmv. The risk matrix was determined by dividing the likelihood and the severity into five levels separately by asset, life, environment and reputation. The piping & instrumentation diagram (P&ID) of the dehydration package was divided into 9 nodes. Total 22 deviations were assessed in consideration of the adsorption and desorption conversion cycle. A risk assessment based on deviations revealed 14 major hazards. Three representative types of hazards were open/close failure of the control valve, control failure of the heater, and abnormal operation of the regeneration gas cooler. Finally, we proposed the installation of additional safety devices to improve safety against these major hazards, such as safety instrumented functions, alarms, etc.

• Journal of Construction Engineering and Project Management
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• 제1권2호
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• pp.1-10
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• 2011

Bridges are critical and valuable components in any road and rail transportation network. Therefore bridge remediation has always been a top priority for asset managers and engineers, but identifying the nature of true defect deterioration and associated remediation treatments remains a complex task. Nowadays Decision Support Systems (DSS) are widely used to assist decision makers across an extensive spectrum of unstructured decision environments. The main objective of this research is to develop a requirements-driven methodology for bridge monitoring and maintenance which has the ability to assess the bridge condition and find the best remediation treatments using Simple Multi Attribute Rating Technique (SMART); with the aim of maintaining a bridge within acceptable limits of safety, serviceability and sustainability.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2001-2006
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• 2008

The most concerning issue of these days is the energy crisis by increasing threat of dependency on foreign oil and its volatility itself. In the situations, the PHEV is drawing attention for the next generation's car which could give a chance to decrease the dependency on foreign oil. As well as, the Korean electric power infrastructure is a strategic national asset that is under utilized most of the time. With the proper changes in the operational paradigm, it could generate and deliver necessary energy to charge the PHEVs which could penetrate the market within few years. In doing so, it would reduce greenhouse gas emissions, improve the economics of the electricity industry, and reduce the energy dependency. This paper investigate the technical potential and impacts of using the existing idle capacity of the electric infrastructure in conjunction with the emerging PHEVs technology to meet the majority of daily energy needs of the Korean LDV fleet.

• 정보보호학회논문지
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• 제13권5호
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• pp.69-79
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• 2003

업무연속성 관점에서 IDEF 접근방법에 의해서 주요 업무 프로세스를 파악하고, 관련 정보자산을 Skandia 모형으로 식별 한 후에, OCTAVE 접근방법에 의해서 위협을 단계적으로 분석하기 위해서, Nessus Version 1.4.2를 이용하여 도서관 정보시스템 중에서 가장 중요한 자산인 서버에 대해서 취약성을 평가했다. 기존 OCTAVE 접근방법에 IDEF 접근방법과 Skandia 모형을 동시에 이용하는 개선된 OCTAVE 접근방법을 이용한 취약성 평가 사례를 제시했다.

• 국제학술발표논문집
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• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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• pp.52-57
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• 2011

Bridges are essential and valuable elements in road and rail transportation networks. Bridge remediation is a top priority for asset managers, but identifying the nature of true defect deterioration and associated remediation treatments remains a complex task. Nowadays Decision Support Systems (DSS) are used extensively to assist in decision-making across a wide spectrum of unstructured decision environments. In this paper a requirements-driven framework is used to develop a risk based decision support model which has the ability to quantify the bridge condition and find the best remediation treatments using Multi Attribute Utility Theory (MAUT), with the aim of maintaining a bridge within acceptable limits of safety, serviceability and sustainability.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2008년도 정기학술발표대회 논문집
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• pp.401-404
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• 2008

공공시설물 중 교량은 열악한 환경에 노출되는 특성과 자연재해 및 물동량의 증대와 운송수단의 대형화로 인해 교통량 및 통행하중의 지속적인 증가 등을 통하여 열화가 점차 진행되게 된다. 교량의 파손으로 인한 보수보강 및 교체에 따른 교통통제, 극단적인 경우 갑작스런 붕괴 등이 발생할 경우 사회경제적으로 커다란 손실뿐만 아니라, 다른 도로시설물과는 달리 인명사상의 피해를 직접적으로 유발할 수 있기 때문에 일정 수준 이상의 성능을 반드시 유지하여야 한다. 따라서 지속적으로 증가할 것으로 예상되는 교량의 유지관리비용의 증가와 적절한 수준의 유지관리 목표를 달성하기 위한 예산의 효율적인 분배 및 최적화를 위하고 이를 통하여 교량의 성능향상 및 사용성을 증대시키기 위하여 자산관리 기법의 도입이 절실히 필요한 실정이다. 자산관리기법의 도입에 있어 교량의 성능을 파악하기 위한 성능평가지수 (Performance measure)를 활용하는데, 이 연구에서는 이러한 성능지수에 대하여 그 기초적 정의 및 역할을 기술하고자 한다.

• Wind and Structures
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• 제39권1호
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• pp.1-14
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• 2024

Widespread damages from extreme winds have attracted lots of attentions of the resilience assessment of power distribution systems. With many related environmental parameters as well as numerous power infrastructure components, such as poles and wires, the increased challenge of power asset management before, during and after extreme events have to be addressed to prevent possible cascading failures in the power distribution system. Many extreme winds from weather events, such as hurricanes, generate widespread damages in multiple areas such as the economy, social security, and infrastructure management. The livelihoods of residents in the impaired areas are devastated largely due to the paucity of vital utilities, such as electricity. To address the challenge of power grid asset management, power system clustering is needed to partition a complex power system into several stable clusters to prevent the cascading failure from happening. Traditionally, system clustering uses the Binary Decision Diagram (BDD) to derive the clustering result, which is time-consuming and inefficient. Meanwhile, the previous studies considering the weather hazards did not include any detailed weather-related meteorologic parameters which is not appropriate as the heterogeneity of the parameters could largely affect the system performance. Therefore, a fragility-based network hierarchical spectral clustering method is proposed. In the present paper, the fragility curve and surfaces for a power distribution subsystem are obtained first. The fragility of the subsystem under typical failure mechanisms is calculated as a function of wind speed and pole characteristic dimension (diameter or span length). Secondly, the proposed fragility-based hierarchical spectral clustering method (F-HSC) integrates the physics-based fragility analysis into Hierarchical Spectral Clustering (HSC) technique from graph theory to achieve the clustering result for the power distribution system under extreme weather events. From the results of vulnerability analysis, it could be seen that the system performance after clustering is better than before clustering. With the F-HSC method, the impact of the extreme weather events could be considered with topology to cluster different power distribution systems to prevent the system from experiencing power blackouts.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.372-378
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• 2018

Life management technology is required as the failure risk of aged power transformers increases. Asset management technology is developed to evaluate the remaining life, establish the replacement strategies, and decide the optimal investment based on the reliability and economy of power transformers. The remaining life assessment uses data such as installation, operation, maintenance, refurbishment, and failure of power transformers. The optimal investment also uses data such as maintenance, outage, and social costs. To develop the asset management system for power transformers, determining the degradation parameters related to the aging of power transformers and evaluating the condition of power transformers using these parameters are important. In this study, since 1983, 110,000 Dissolved Gas Analysis (DGA) data have been analyzed to determine the degradation parameters related to the aging of power transformers. The alarm rates of combustible gases ($H_2$, $C_2H_2$, $C_2H_4$, $CH_4$, and $C_2H_6$), TCG, CO, and $CO_2$ were analyzed. The end of life and failure rate (bathtub curve) of power transformers were also calculated based on the failure data from 1981 to 2014. The DGA gases related to discharge, overheating, and insulation degradation were determined based on alarm and failure rates. $C_2H_2$, $C_2H_6$, and $CO_2$ were discharge, oxidation, and insulation degradation parameters related to the aging of power transformers.

• KEPCO Journal on Electric Power and Energy
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• 제3권1호
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• pp.23-28
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• 2017

The life management technology becomes important as the failure risk of the aged power transformers increases. Asset management technology, therefore, has been developed to evaluate the remaining life and build replacement strategies of power transformers, which enables an optimal investment decisions based on reliability and economic feasibility. The remaining life assessment technology uses data related to such as installation, operation, maintenance, refurbishment, and disposed history of power transformers. The optimal investment decision additionally uses data related to failure and social costs. To develop the asset management technology in power transformers, it is important to find deterioration parameters directly indicating degradation of power transformers. In this study, 110,000 DGA data during the past 35 years have been analyzed in order to find the deterioration parameters related to the degradation of power transformers. The alarm rates of combustible gases ($H_2$, $C_2H_2$, $C_2H_4$, $CH_4$, $C_2H_6$), TCG CO, and $CO_2$ were analyzed as deterioration parameters. The origin of the gas was discussed in connection with discharge, overheating and insulation aging.

• Nuclear Engineering and Technology
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• 제51권1호
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• pp.138-145
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• 2019

With the application of digital technology to safety-critical infrastructures, cyber-attacks have emerged as one of the new dangerous threats. In safety-critical infrastructures such as a nuclear power plant (NPP), a cyber-attack could have serious consequences by initiating dangerous events or rendering important safety systems unavailable. Since a cyber-attack is conducted intentionally, numerous possible cases should be considered for developing a cyber security system, such as the attack paths, methods, and potential target systems. Therefore, prior to developing a risk-informed cyber security strategy, the importance of cyber-attacks and significant critical digital assets (CDAs) should be analyzed. In this work, an importance analysis method for cyber-attacks on an NPP was proposed using the probabilistic safety assessment (PSA) method. To develop an importance analysis framework for cyber-attacks, possible cyber-attacks were identified with failure modes, and a PSA model for cyber-attacks was developed. For case studies, the quantitative evaluations of cyber-attack scenarios were performed using the proposed method. By using quantitative importance of cyber-attacks and identifying significant CDAs that must be defended against cyber-attacks, it is possible to develop an efficient and reliable defense strategy against cyber-attacks on NPPs.