• 한국소음진동공학회논문집
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• 제21권12호
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• pp.1098-1103
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• 2011

The structural integrity of APR1400 reactor vessel internals has been being assessed referring the US Nuclear Regulatory Commission regulatory guide 1.20, comprehensive vibration assessment program. The program is composed of a vibration and stress analysis, a vibration and stress measurement, and an inspection. This paper covers the vibration and stress analysis on the reactor vessel internals by the pulsation of reactor coolant pump. 3-dimensional models to calculate the hydraulic loads and structural responses were built and the pressure distributions and the structural responses were predicted using ANSYS. This paper presents that APR1400 reactor vessel internals have enough structural integrity against the pulsation of reactor coolant pump as the peak stress of the reactor vessel internals is much lower than the acceptance limit.

• 한국소음진동공학회논문집
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• 제21권8호
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• pp.708-713
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• 2011

U.S. nuclear regulatory commission(NRC) regulatory guide(RG) 1.20 requires a comprehensive vibration assessment program(CVAP) for use in verifying the structural integrity of reactor vessel internals(RVI) for flow-induced vibrations prior to commercial operation. The CVAP program consist of vibration and fatigue analysis, a vibration measurement program, an inspection program, and a correlation of their results. One of the main purposes of the analysis program is to select measurement locations, however measurement locations can not be determined by only analysis results, therefore we developed selection criteria of measurement locations for advanced power reactor 1400(APR1400) RVI CVAP, It will be used to select measurement locations and instrument types for APR1400 RVI CVAP.

• 품질경영학회지
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• 제39권2호
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• pp.320-328
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• 2011

This research proposes comprehensive models for analyzing common cause failures (CCF) due to cumulative shocks and to assess system reliability under the CCF. The proposed cumulative shock models are based on the binomial failure rate (BFR) model. Six kinds of models are proposed so as to explain diverse cumulative shock phenomena. The models are composed of the initial failure probability, shape parameter, and the total shock number. Some parameters of the proposed models can not be explicitly estimated, so we adopt the Expectation-maximization (EM) algorithm in order to obtain the maximum likelihood estimator (MLE) for the parameters. By estimating the parameters for the cumulative shock models, the system reliability with CCF can be assessed sequentially according to the number of cumulative shocks. The result can be utilizes in dynamic probabilistic safety assessment (PSA), aging studies, or risk management for nuclear power plants. Replacement or maintenance policies can also be developed based on the proposed model.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.415-419
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• 2015

Engineering is a value-adding process applying knowledge and skills in the construction industry that includes the planning, feasibility study, project management (PM), front end engineering and design (FEED), detail design, procurement, construction, supervision, and operation. Among these engineering activities, FEED is defined as a comprehensive design practice in the early design phase focused on conceptual design and basic design. It is a particularly influencing area that determines the competitiveness of procurement and construction capability of construction firms (KNIN 2013). Nevertheless, previous studies in FEED have been limited to the design process, deliverable, or particular management technique (e.g. system engineering, collaboration, information etc.). In this context, the purpose of this study is to propose a comprehensive FEED business process structure for project management of thermal power plant construction projects encompassing the entire project life cycle. And an assessment methodology for FEED functions was developed. It is expected that the proposed structure of FEED functions and FEED evaluation methodology will contribute to improvement of competitive capability of engineering, procurement, and construction (EPC) companies.

• 산업진흥연구
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• 제8권3호
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• pp.201-210
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• 2023

본 연구는 데이터 생태학 이론에 기초하여 중국 지방자치단체의 공개 공공 데이터를 연구 대상으로 삼았다. 데이터 자산가치 평가방법을 데이터 비즈니스 운영의 새로운 관점에서 비교하였다. 계층적 분석방법(AHP)을 사용한 평가 모형을 이용한 연구결과는 전통적인 비용, 수익 및 시장 방법보다 정부 개방형데이터 자산의 상업적 가치를 더 객관적으로 반영할 수 있었으며, 데이터 가치지수를 종합적으로 평가할 수 있다는 장점을 보여주었다. 그리고 지역 데이터 가치에 대한 종합적인 검색결과를 더 잘 반영되고 있었다. 자료를 보면 지방정부의 데이터 가치평가지수는 지역의 디지털 경제발전지수에 비례하여 디지털 경제에 대한 효과가 나타났다. 본 연구는 지방정부의 데이터 가치를 이해하는데 기여하였다. 이로 인하여 데이터 혁신 및 데이터 비즈니스 운영모델구축을 촉진하고, 사회복지를 개선하며, 데이터 실현을 위해 디지털 경제의 빠른 발전을 촉진하는 연구 및 실천하는 계기를 만들고자 하였다.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2000년도 추계학술대회
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• pp.57-74
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• 2000

This paper examined current problem of reliability assessment project on mechanical components being domestically pursued, and from the point of new view suggested directions to a comprehensive reliability assurance added quality assurance, suitable to realities in our industries.

• 한국해양공학회지
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• 제25권4호
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• pp.54-58
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• 2011

The need and importance of developing and utilizing the oceans, not only as sources of renewable energy and mineral resources, but also as countermeasures to global warming such as for CCS (carbon capture and storage), have continued to increase, especially in countries with limited land areas and resources. Therefore, it is necessary to assess the sustainability of an ocean utilization technology or system not only from an economic point of view but also from an ecological one. For this purpose, it might be effective to develop a comprehensive evaluation method and/or index, by which the assessment of and decisions about a technology and system can be made more objectively. It would also be useful to have an environmental simulation model, which was developed and reported in a previous research. The aim of this study was to modify a reasonable and quantitative index, with which a comprehensive evaluation system can be established, to assess environmental sustainability and risk.

• Nuclear Engineering and Technology
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• 제45권2호
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• pp.249-256
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• 2013

In accordance with the US Nuclear Regulatory Commission (US NRC), Regulatory Guide 1.20, the reactor vessel internals comprehensive vibration assessment program (RVI CVAP) has been developed for an Advanced Power Reactor 1400 (APR1400). The purpose of the RVI CVAP is to verify the structural integrity of the reactor internals to flow-induced loads prior to commercial operation. The APR1400 RVI CVAP consists of four programs (analysis, measurement, inspection, and assessment). Thoughtful preparation is essential to the measurement program, because data acquisition must be performed only once. The optimized design of a vibration and stress measurement system for the RVI CVAP is essential to verify the integrity of the APR1400 RVI. We successfully designed a vibration and stress measurement system for the APR1400 RVI CVAP based on the design materials, the hydraulic and structural analysis results, and performance tests of transducers in an extreme environment. The measurement system designed in this paper will be utilized for the APR1400 RVI CVAP as part of the first construction project in Korea.

• Nuclear Engineering and Technology
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• 제55권2호
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• pp.530-545
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• 2023

As an alternative to conventional management options for a lot of concrete waste from decommissioning of nuclear power plants, a set of scenarios for controlled recycling of decommissioning concrete waste as engineered barriers of a radioactive waste repository was proposed, and a comprehensive safety assessment model and framework covering both pre-and post-closure phases was newly developed. The new methodology was applied to a reference vault-type repository, and the ratios of derived concentration limits to unconditional clearance levels of eighteen radionuclides for controlled recycling were provided for three sets of dose criteria (0.01, 1, and 20 mSv/y for the pre-closure and 0.01 mSv/y for the post-closure phases). It turns out that decommissioning concrete waste whose concentration is much higher than the unconditional clearance level can be recycled even when the dose criterion 0.01 mSv/y is applied. Moreover, a case study on ABWR bio-shield shows that the fraction of recyclable concrete waste increases significantly by increasing the dose criterion for the radiation worker in the pre-closure phase or the duration of storage prior to recycling. The results of this study are expected to contribute to demonstrating the feasibility of controlled recycling of a lot of decommissioning concrete waste within nuclear sectors.

• Korean Journal of Radiology
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• 제25권6호
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• pp.518-539
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• 2024

Coronary computed tomography angiography (CCTA) has emerged as a pivotal tool for diagnosing and risk-stratifying patients with suspected coronary artery disease (CAD). Recent advancements in image analysis and artificial intelligence (AI) techniques have enabled the comprehensive quantitative analysis of coronary atherosclerosis. Fully quantitative assessments of coronary stenosis and lumen attenuation have improved the accuracy of assessing stenosis severity and predicting hemodynamically significant lesions. In addition to stenosis evaluation, quantitative plaque analysis plays a crucial role in predicting and monitoring CAD progression. Studies have demonstrated that the quantitative assessment of plaque subtypes based on CT attenuation provides a nuanced understanding of plaque characteristics and their association with cardiovascular events. Quantitative analysis of serial CCTA scans offers a unique perspective on the impact of medical therapies on plaque modification. However, challenges such as time-intensive analyses and variability in software platforms still need to be addressed for broader clinical implementation. The paradigm of CCTA has shifted towards comprehensive quantitative plaque analysis facilitated by technological advancements. As these methods continue to evolve, their integration into routine clinical practice has the potential to enhance risk assessment and guide individualized patient management. This article reviews the evolving landscape of quantitative plaque analysis in CCTA and explores its applications and limitations.