• Journal of the Korean Society of Systems Engineering
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• v.12 no.2
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• pp.69-80
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• 2016

The purpose of this study is to establish a component reutilization system in Nuclear Power Plant (NPP) by Object-Oriented Systems Engineering Method (OOSEM). Unified Modeling Language (UML) is mainly used for OOSEM. Operational Concept (OpsCon), Use cases, Structure Diagrams, and Behavior Diagrams are developed to analyze stakeholders needs, system requirements, logical architecture, and physical architecture. Based on the current decommissioning and purchasing system of the component, some activities from their systems were excepted and additional new activities were developed for a component reutilization system.

• Journal of the Korean Society of Systems Engineering
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• v.12 no.1
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• pp.41-58
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• 2016

Reliability Centered Maintenance (RCM) introduces a systematic method and decision logic tree for utilizing previous operating experience focused on reliability and optimization of maintenance activities. In this paper RCM methodology is applied on safety injection system for APR-1400. Functional Failure Mode Effects and Criticality Analysis (FME&CA) are applied to evaluate the failure modes and the effect on the component, system and plant. Logic Tree Analysis (LTA) is used to determine the optimum maintenance tasks. The results show that increasing the condition based maintenance will reduce component failure and improve reliability and availability of the system. Also the extension of the surveillance test interval of Safety Injection Pumps (SIPs) would lead to an improved pump's availability, eliminate the unnecessary maintenance tasks and this will optimize maintenance activities.

• Journal of the Korean Society of Systems Engineering
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• v.10 no.1
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• pp.17-32
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• 2014

The trade-off studies in the concept development stage to assess the relative goodness of alternative systems concepts for AE (architect engineering) design for the Barge Mounted SMR (BMSMR) is introduced. With respect to design margin, system performance, schedule and risk, the design selection is cond ucted using the following characteristics; barge mobility, system safety under the natural disaster (seismic), power output, interfacing with the other system, and the additional supporting functions as desalination. There are three findings that should be remedied; deficiencies in the assumed characteristics of the system being modeled, deficiencies in the test model, and excessively stringent system requirements. This study is performed using systems engineering approach with trade off matrix method. In order to execute this work, concept development stage is divided into three (3) phases as NA (needs analysis), CE (concept exploration), and CD (concept definition).

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1951-1966
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• 2007

This research attempts to examine the effects of import penetration in an industry on the firms' decision of business diversification and provide an integrative framework including the determinants and results of the business diversification. The research results are as follows. First, the import penetration doesn't affect the degree of business diversification. Second, the more profitable their core business industry, the lower the degree of business diversification against the import penetration. In addition, both technology-related assets and marketing-related assets are necessary for business diversification when faced with the import penetration. Finally, the inverted U-shaped relationship is supported between the degree of business diversification and firm performance.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2006.06a
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• pp.133-140
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• 2006

유비쿼터스 컴퓨팅 기술이 발전함에 따라 상황인지는 유비쿼터스 환경을 구성하는 중요한 요소들 중의 하나로 안정되고 있다. 그러나 아직까지 모든 유비쿼터스 컴퓨팅 환경에 적용될만한 일반적인 상황모형 (generic context model)은 제시되지 못하고 있다. 따라서 본 논문의 목적은 혼합형 다단계(hybrid multi-level) 다이어그램을 이용해 보다 적합한 일반적 상황모형을 제안하는 것이다. 이를 위해 먼저 기존의 다양한 상황 모형들을 분석하고 이를 토대로 유비쿼터스 지능 공간에서의 컴퓨팅 시스템 환경에 적합한 일반적 상황모형을 제안하였다.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2006.06a
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• pp.141-151
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• 2006

최근 U-City와 같은 유비쿼터스 지능 공간 (Ubiquitous Smart Space, USS) 개발이 추진됨에 따라 USS 요구 분석 방법론에 대한 필요성이 커지고 있다. 그러나 SDLC, UML 등과 같은 기존 정보시스템 요구분석 등 개발 방법론은 상황인지 에이전트 시스템 등과 같은 USS 특유의 환경을 고려하지 못해 USS 요구 분석 방법론으로 그래도 적용하기에는 한계가 있다. 따라서 본 논문은 USS 개발을 위한 요구분석 방법론으로서 기존 UML에 상황인지, 에이전트 시스템의 특정을 고려하여 수정된 UML(Amended UML)을 제시하는 것을 목적으로 한다. 이를 위해 본 논문에서는 As-Is Space 와 To-Be Space 로 나누어 요구 분석을 하였다. 또한 본 논문에서 제시한 요구 분석 방법론의 활용가능성을 보이기 위해 국내 쇼핑몰 내 실제 USS 서비스 개발에 적용해 보았다.

• Journal of Forest and Environmental Science
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• v.29 no.2
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• pp.125-130
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• 2013

An attempt was made on pulp production from the fast growing plant, Acacia hybrid to determine the total yield, screened yield, Kappa number, and fibre morphology of organosolv Acacia hybrid pulp. Uniform-sized chips were taken to undergo pulping in a digester with five different concentrations of ethanol, 50%, 60%, 70%, 80% and 90% (v/v) with 1 M of sodium hydroxide as catalyst. All chips were digested in a temperature-controlled digester with constant amount of water added and temperature of $185^{\circ}C$ with the duration of three hours cooking time and correspond pressure 1.1-1.2 MPa. It was observed that increasing of ethanol concentration has led to pulp yield increment and decreased in the degree of delignification at the same time. This study was aimed to focus on the effect of the varied concentration of organic solvent towards the pulp yield and its relationship with Kappa number and pulp yield.

• Nuclear Engineering and Technology
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• v.49 no.3
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• pp.525-533
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• 2017

A new concept termed the Innovative Nuclear Power Plant Building Arrangement (INBA) strategy is a new nuclear power plant building arrangement method which encompasses upfront consideration of more efficient decommissioning. Although existing decommissioning strategies such as immediate dismantling and differed dismantling has the advantage of either early site restoration or radioactive decommissioning waste reduction, the INBA strategy has the advantages of both strategies. In this research paper, the concept and the implementation method of the INBA strategy will be described. Two primary benefits will be further described: (1) early site restoration; and (2) radioactive waste reduction. Several other potential benefits will also be identified. For the estimation of economic benefit, the INBA strategy, with two primary benefits, will be compared with the immediate dismantling strategy. The effect of a short life cycle nuclear power plant in combination with the INBA strategy will be reviewed. Finally, some of the major impediments to the realization of this strategy will be discussed.

• New & Renewable Energy
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• v.17 no.2
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• pp.1-8
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• 2021

We estimated the price range of electricity transactions under the prosumer system, considering the spread of renewable energy and the prospect of introducing a surplus power trading system between power consumers in Korea. The range (min/max) of power transaction prices was estimated by prosumers and consumers who could purchase electricity from utilities if needed. It is assumed that utilities purchased electricity from prosumers and consumers under a Time-of-Use (TOU) rate, trading at a monthly price. The range of available transaction prices according to the amount of power purchased from utilities and the amount of transaction power was also estimated. The price range that can be traded is expected to vary depending on variables such as the TOU rate, purchased and surplus power, levelized cost of electricity, etc.

• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3787-3800
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• 2023

Reactivity Initiated Accident (RIA) scenarios require special attention using advanced simulation techniques due to their complexity and importance for nuclear power plant (NPP) safety. While the conservative approach has traditionally been used for safety analysis, it may lead to unrealistic results which calls for the use of best estimate plus uncertainty (BEPU) approach, especially with the current advances in computational power which makes the BEPU analysis feasible. In this work an Uncontrolled Control Element Assembly (CEA) Withdrawal at Full Power accident scenario is analyzed using the BEPU approach by loosely coupling the thermal hydraulics best-estimate system code (RELAP5/SCDAPSIM/MOD3.4) to the statistical analysis software (DAKOTA) using a Python interface. Results from the BEPU analysis indicate that a realistic treatment of the accident scenario yields a larger safety margin and is therefore encouraged for accident analysis as it may enable more economic and flexible operation.