• 한국압력기기공학회 논문집
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• 제13권2호
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• pp.51-59
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• 2017

Steam jets ejected from a rupture zone of high energy pipes may cause damage to adjacent structures. This event could lead to more serious accidents in nuclear power plants. Therefore, to prevent serious accidents, high energy pipes of nuclear power plants are designed according to the ANSI / ANS 58.2 technical standard. However, the US Nuclear Regulatory Commission (USNRC) has recently pointed out non-conservatism in existing high energy pipe fracture evaluation methods, and required the assessment of the unsteady load of the jet caused by a potential feedback mechanism as well as the impact range of steam jet, the jet impact loads and the blast wave effects at the initial breakage stage. The potential feedback mechanism refers to a phenomenon in which a vortex formed by impingement jets amplifies vortex itself and induces jet vibration in a shear layer. In this study, CFD methodology using the LES turbulence model is established and numerical analysis is carried out to evaluate the dynamic behavior of impingement jets and the potential feedback mechanism during jet impingement. Obtained results have been compared with an empirical correlation and experiment.

• Ocean Systems Engineering
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• 제8권1호
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• pp.21-32
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• 2018

Due to the escalation in hydrocarbon consumption, the offshore industry is now looking for advanced technology to be employed for deep sea exploration. Riser system is an integral part of floating structure used for such oil and gas extraction from deep water offering a system of drill twines and production tubing to spread the exploration well towards the ocean bed. Thus, the marine risers need to be precisely employed. The incorporation of the strengthening material, fiber reinforced polymer (FRP) for deep and ultra-deep water riser has drawn extensive curiosity in offshore engineering as it might offer potential weight savings and improved durability. The design for FRP strengthening involves the local design for critical loads along with the global analysis under all possible nonlinearities and imposed loadings such as platform motion, gravity, buoyancy, wave force, hydrostatic pressure, current etc. for computing and evaluating critical situations. Finite element package, ABAQUS/AQUA is the competent tool to analyze the static and dynamic responses under the offshore hydrodynamic loads. The necessities in design and operating conditions are studied. The study includes describing the methodology, procedure of analysis and the local design of composite riser. The responses and fatigue damage characteristics of the risers are explored for the effects of FRP strengthening. A detail assessment on the technical expansion of strengthening riser has been outlined comprising the inquiry on its behavior. The enquiry exemplifies the strengthening of riser as very potential idea and suitable in marine structures to explore oil and gas in deep sea.

• Smart Structures and Systems
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• 제20권3호
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• pp.385-396
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• 2017

The recent advancements in sensing technologies allow us to record measurements from target structures at multiple locations and with relatively high spatial resolution. Such measurements can be used to develop data-driven methodologies for condition assessment, control, and health monitoring of target structures. One of the state-of-the-art technologies, Fiber Optic Strain Sensors (FOSS), is developed at NASA Armstrong Flight Research Center, and is based on Fiber Bragg Grating (FBG) sensors. These strain sensors are accurate, lightweight, and can provide almost continuous strain-field measurements along the length of the fiber. The strain measurements can then be used for real-time shape-sensing and operational load-estimation of complex structural systems. While several works have demonstrated the successful implementation of FOSS on large-scale real-life aerospace structures (i.e., airplane wings), there is paucity of studies in the literature that have investigated the potential of extending the application of FOSS into civil structures (e.g., tall buildings, bridges, etc.). This work assesses the feasibility of using FOSS to predict operational loads (e.g., wind loads) on chain-like structures. A thorough investigation is performed using analytical, computational, and experimental models of a 4-story steel building test specimen, developed at the University of Southern California. This study provides guidelines on the implementation of the FOSS technology on building-like structures, addresses the associated technical challenges, and suggests potential modifications to a load-estimation algorithm, to achieve a robust methodology for predicting operational loads using strain-field measurements.

• 한국안전학회지
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• 제33권5호
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• pp.157-163
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• 2018

This paper describes design improvement to a research rector for safety enhancement using Probabilistic Safety Assessment (PSA). This PSA under reactor design was undertaken to assess the level of safety for the design of a research reactor and to evaluate whether it is probabilistically safe to operate and reliable to use. The scope of the PSA reported here is a Level 1 PSA, which addresses the risks associated with the core damage. The technical objectives of this study were to identify accident sequences leading to core damage and to derive design improvement from the dominant accident sequences through the sensitivity analysis. The AIMS-PSA and FTREX were used for the this PSA of the research reactor. The criterion for inclusion was all sequences with a point estimate frequency greater than a truncation value of 1.0E-14/yr. The final result indicates a point estimate of 6.79E-05/yr for the overall Core Damage Frequency (CDF) attributable to internal initiating events for the research reactor under design. Based on the dominant accident sequences from the PSA, the seven kinds of sensitivity analysis were performed and some design improvement items were derived. When the five methods to improve the safety were all applied to the reactor design and emergency operating procedure, its risk was reduced to about 1.21E-06/yr from 6.79E-05/yr. The contribution of LOCA and LOEP with high CDF were significantly reduced by the sensitivity analysis. The safety of the research reactor was well improved and the risk was reduced than before adapting the design improvement gotten from the sensitivity analysis. The present study indicated that the research reactor has the well-balanced safety in regard to each initiating event contribution to CDF. The PSA methodology is very effective to improve reactor safety in a conceptual design phase and especially, Risk-informed design(RID) is very nice way to find the deficiencies of research reactor under design and to improve the reactor safety by solving them.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.459-464
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• 2006

It has been well proved that shiphandling simulators are efficient and useful facilities for training and education of cadets and seafarers. Most of the maritime universities and many maritime training institutes all over the world have installed shiphandling simulators, which play important roles in maritime education and training. However, most of the Shiphandling simulators are standalone facilities with diversities on system architectures, layouts and functions. STCW78/95 requires simulators used for simulator-based training shall be suitable for the selected objectives and training tasks. To ensure the shiphandling simulator facilities meet the requirements of STCW convention and other expanded applications, collaborated research and coordination are needed in development and application of shiphandling simulators. Performance standard should be established for shiphandling simulator systems considering the advanced research needs as well as the needs in education, training, and assessment of competence. Standardizing and exchanging shiphandling mathematical models will improve critical performance of the system. Cooperated research on model course and training assessment approaches will enhance the training standard. In addition, the rapid spread of the internet technology has shown a promising future of application of shiphandling simulators through internet. Research has been carried out on internet based integration of multiple shiphandling simulators. A multi-agent based system, including necessary hardware, has been developed. Collaborated operation of the system can be of benefit in filling the gaps of the technical and operational level and methodology between maritime universities, enhancing mutual understanding of the navigation customs and culture background among cadets and seafarers from different countries, facilitating communication and maritime English training, and extending the functions of shiphandling simulators.

• 한국가스학회지
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• 제21권1호
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• pp.43-51
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• 2017

국내 냉동제조시설에서 암모니아 누출사고가 여전히 발생하고 있음을 볼 수가 있다. 암모니아는 가연성가스 및 독성가스이므로 사고 발생할 때 인체와 생태계에 큰 피해를 일으킬 수 있다. 국내 냉동제조시설의 암모니아 사고유형을 파악한 후 사고시나리오를 선정하여 피해범위를 산정하고 사고 빈도와 위험도를 분석하여 사고 피해를 최소화하는 대책 수립이 필요하다. 본 연구에서는 정량적 위험성 평가(QRA: quantitative risk assessment)의 분석 방법에 따라 암모니아 냉동시스템의 리시버 탱크에 대한 위험도를 분석하였다. 시나리오 분석 조건은 화학물질관리법에서 정하는 '사고시나리오 선정에 관한 기술지침' 및 미국 화학공정안전센터(CCPS: center for chemical process safety)의 가이드라인에 따라 정하였다. DVN사의 SAFETI 프로그램을 활용하여 시나리오에서 선정된 모든 사고 영향범위를 산정하고 빈도 분석을 통하여 리시버 탱크에 대한 위험도를 도출하였다. 빈도 값은 사건수 분석(ETA: event tree analysis)기법과 Part count 기법을 활용하였다. 연구 결과 암모니아 냉동시스템의 개인적 위험도는 7.71E-04/yr으로 도출되었으며, 사회적 위험도 1.17E-03/yr으로 도출되었다. 도출된 위험도는 국제 화재방지협회 (NFPA: national fire protection association)의 ALARP (as low as reasonably practicable) 범위를 적용하여 위험도의 적합성을 확인하였으며, 본 연구에서 제안한 위험도 산정 방법이 사고 피해 최소화 방안을 모색하는데 활용된다면 보다 좋은 결과가 도출될 것으로 판단된다.

• 청정기술
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• 제17권4호
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• pp.285-299
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• 2011

2007년 6월 시행된 유럽 신(新)화학물질관리제도(REACH, Registration, Evaluation, Authorization and Restriction of CHemicals)에서 물질 제조자가 공급망 상 제공해야 하는 법적 의무 사항인 확장된물질안전보건자료(eSDS, extended Safety Data Sheet)에 대하여, 본 총설에서는 eSDS의 개념 파악과 함께 노출시나리오(ES, Exposure Scenario) 작성 방법에 대한 유럽의 개발 동향을 기반으로 노출시나리오의 구성요소 및 각 구성요소별 주요 입력정보 그리고 단계별 노출시나리오 작성 방법을 알아보았다. 노출시나리오 작성에 필요한 정보로는 용도기술어 시스템(UDS, Use Descriptor System), 작업조건(OC, Operational Condition) 및 위해성관리대책(RMM, Risk Management Measure)이 조사되어 이에 대해 구체적인 이해를 도모하였다. 근로자, 환경, 소비자를 평가 대상으로 하는 기존의 주요 노출 평가 툴의 특징을 살펴보고, REACH 하의 노출시나리오 생성을 실행하기 위해 유럽화학물질청(ECHA, European Chemicals Agency)에서 최종 개발하여 발표한 노출 평가 툴인 Chesar (Chemical Safety Assessment and Report tool)의 구성을 알아보았다. EU 집행위에서 개발한 유기용매 분야의 일반 노출시나리오 (GES, Generic Exposure Scenario) 사례를 소개하였고, 3단계로 구분할 수 있는 노출시나리오 작성 과정 중에서 국내 수출 중소기업에서 담당할 부분 및 활용 방안을 제시하였다.

• 대한토목학회논문집
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• 제43권1호
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• pp.63-69
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• 2023

'탄소중립 기술적용 시나리오 모형 (CATAS; Carbon-neutrality Assessment based on Technology Application Scenario)'은 공간 단위에서 에너지전환, 수송, 건물 등 분야에 탄소중립 기술을 적용했을 경우 온실가스 감축 효과성 분석을 제공한다. 모형의 개발범위는 온실가스 배출원은 온실가스 직접배출량 대상으로 분석하며, 공간적 범위는 직접·간접배출의 경계를 공간적 범위로 설정하였다. 그리고 기술적 범위는 2050 탄소중립 시나리오에서 온실가스 배출량이 가장 큰 전환부문의 9개 기술과 산림 흡수원을 포함하였다. 탄소중립률 평가 방법론은 ①온실가스 배출현황 분석, ②기술도입에 따른 에너지생산량 예측, ③온실가스 감축량 산정, ④탄소중립률 산정까지 4단계로 이루어져있다. 웹기반 CATAS-BASIC을 개발 한 후 서울시의 ｢2050 온실가스 감축추진계획｣상 제시된 신재생에너지 보급목표를 적용하여 분석을 실시하였다. 태양광·수소연료전지·수열을 적용한 결과, 서울시의 전환부문 배출량인 1.49백만 tCO₂eq 중 기술도입으로 0.43백만 tCO₂eq 감축하여 전환부문 탄소중립률은 28.94 %로 분석되었다.

• International Journal of Automotive Technology
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• 제4권2호
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• pp.77-86
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• 2003

How to compare the environmental damage caused by vehicles with different foe]s and drive trains\ulcorner This paper describes a methodology to assess the environmental impact of vehicles, using different approaches, and evaluating their benefits and limitations. Rating systems are analysed as tools to compare the environmental impact of vehicles, allowing decision makers to dedicate their financial and non-financial policies and support measures in function of the ecological damage. The paper is based on the "Clean Vehicles" research project, commissioned by the Brussels Capital Region via the BIM-IBGE (Brussels Institute for the Conservation of the Environment) (Van Mierlo et at., 2001). The VriJe Universiteit Brussel (ETEC) and the universite Libre do Bruxelles (CEESE) have jointly carried out the workprogramme. The most important results of this project are illustrated in this paper. First an overview of environmental, economical and technical characteristics of the different alternative fuels and drive trains is given. Afterward the basic principles to identify the environmental impact of cars are described. An outline of the considered emissions and their environmental impact leads to the definition of the calculation method, named Ecoscore. A rather simple and pragmatic approach would be stating that all alternative fuelled vehicles (LPG, CNG, EV, HEV, etc.) can be considered as ′clean′. Another basic approach is considering as ′clean′ all vehicles satisfying a stringent omission regulation like EURO IV or EEV. Such approaches however don′t tell anything about the real environmental damage of the vehicles. In the paper we describe "how should the environmental impact of vehicles be defined\ulcorner", including parameters affecting the emissions of vehicles and their influence on human beings and on the environment and "how could it be defined \ulcorner", taking into account the availability of accurate and reliable data. We take into account different damages (acid rain, photochemical air pollution, global warming. noise, etc.) and their impacts on several receptors like human beings (e.g., cancer, respiratory diseases, etc), ecosystems, or buildings. The presented methodology is based on a kind of Life Cycle Assessment (LCA) in which the contribution of all emissions to a certain damage are considered (e.g. using Exposure-Response damage function). The emissions will include oil extraction, transportation refinery, electricity production, distribution, (Well-to-Wheel approach), as well as the emission due to the production, use and dismantling of the vehicle (Cradle-to-Grave approach). The different damages will be normalized to be able to make a comparison. Hence a reference value (determined by the reference vehicle chosen) will be defined as a target value (the normalized value will thus measure a kind of Distance to Target). The contribution of the different normalized damages to a single value "Ecoscore" will be based on a panel weighting method. Some examples of the calculation of the Ecoscore for different alternative fuels and drive trains will be calculated as an illustration of the methodology.

• 항공우주시스템공학회지
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• 제13권6호
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• pp.80-89
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• 2019

효과적인 유망기술 발굴을 위해 미래 사회 변화를 전망하고, 미래기술 도출 방법론 및 프로세스 개선 연구가 필요하며, 연구소·기업에서 기술기획에 활용할 기초자료의 필요성이 꾸준히 대두되고 있다. 따라서 본 연구는 국내 무인항공기산업과 같은 신성장동력산업의 국제적 기술 경쟁력 확보와 시장성 확보 및 산업성장이 가능한 미래유망 기술을 도출하는 방법론을 제시하는 것이다. 이에 본 연구는 KrKwic, Excel, NetMiner등의 분석툴을 활용하여 무인항공기산업 분야의 특허데이터를 대상으로 동시출현 단어를 활용한 소셜네트워크분석과 하위그룹분석, 인지지도분석 방법을 제시하였다. 이를 통해, 무인항공기산업 분야의 기술진화를 탐색하고 유망기술을 예측하는 방법을 제시하였다. 그 결과, '체계연동/통합 기술', '시험평가/감항인증 기술', '항공전자 기술', '비행제어 기술', '피아식별 기술', '비행통제 시스템 기술', '지원장비 기술' 등은 향후 유망한 기술로 선정하여 집중 투자할 필요성이 큰 기술이라 볼 수 있었다.