• Nuclear Engineering and Technology
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• 제50권8호
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• pp.1199-1209
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• 2018

After the Fukushima-Daiichi accident in 2011, the multi-unit risk, i.e., the risk due to several nuclear power plants (NPPs) in a site has become an important issue in several countries such as Korea, Canada, and China. However, the multi-unit risk has been discussed for a long time in the nuclear community before the Fukushima-Daiichi nuclear accident occurred. The regulatory authorities around the world and the international organizations had proposed requirements or guidelines to reduce the multi-unit risk. The concerns regarding the multi-unit risk can be summarized in the following three questions: How much the accident of an NPP in a site affects the safety of other NPPs in the same site? What is the total risk of a site with many NPPs? Will the risk of the simultaneous accidents at several NPPs in a site such as the Fukushima Daiichi accident be low enough? The multi-unit risk assessment (MURA) in an integrated framework is a practical approach to obtain the answers for the above questions. Even though there were few studies to assess the multi-unit risk before the Fukushima-Daiichi nuclear accident, there are still several issues to be resolved to perform the complete MURA. This article aims to provide an overview of the multi-unit risk issues and its assessment. We discuss the several critical issues in the current MURA to get useful insights regarding the multi-unit risk with the current state art of probabilistic safety assessment (PSA) technologies. Also, the qualitative answers for the above questions are addressed.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1482-1494
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• 2022

Power conversion cycles (Subcritical Steam, Supercritical Steam, Open Air Brayton, Recuperated Air Brayton, Combined Cycle, Closed Brayton Supercritical CO₂ (sCO₂), and Stirling) are evaluated for land-based nuclear microreactors based on technical maturity, system efficiency, size, cost and maintainability, safety implications, and siting considerations. Based upon these criteria, Air Brayton systems were selected for further evaluation. A brief history of the development and applications of Brayton power systems is given, followed by a description of how these thermal-to-electrical energy conversion systems might be integrated with a nuclear microreactor. Modeling is performed for optimized cycles operating at 3 MW(e) with turbine inlet temperatures of 500 ℃, 650 ℃ and 850 ℃, corresponding to: a) sodium fast, b) molten salt or heat pipe, and c) helium or sodium thermal reactors, coupled with three types of Brayton power conversion units (PCUs): 1) simple open-cycle gas turbine, 2) recuperated open-cycle gas turbine, and 3) recuperated and intercooled open-cycle gas turbine. Aeroderivative turboshaft engines employing the simple Brayton cycle and two industrial gas turbine engines employing recuperated air Brayton cycles are also analyzed. These engines offer mature technology that can facilitate near-term deployment with a modest improvement in efficiency.

• 한국정보시스템학회지:정보시스템연구
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• 제33권1호
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• pp.115-131
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• 2024

Purpose This study aims to analyse the impact of the development of fintech and the emergence of internet primary banks due to the increasing use of smartphones on the performance of traditional local banks from both financial and non-financial perspectives. Return on equity (ROE) and return on assets (ROA) are used to assess the performance differences between the two types of banks and how these differences are affected by their financial characteristics. Design/methodology/approach Using return on equity (ROE) and return on assets (ROA) as indicators, we identified the differences in operating performance between the two types of banks. In addition, this study analysed the impact of financial characteristics on profitability through regression analysis with various control variables. We further studied the impact of non-financial characteristics (customer reviews, social media reactions, etc.) on operating performance. Findings The net interest margin ratio of local banks had a positive impact, while the marketable securities ratio of Internet primary banks had a negative impact. The non-financial analysis shows that the number of customer reviews and social media reactions have a significant impact on the performance of Internet primary banks, suggesting that customer satisfaction and positive market perception are important factors in the performance of Internet primary banks.

• Nuclear Engineering and Technology
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• 제56권8호
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• pp.3155-3166
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• 2024

While several nuclear energy newcomer (NEN) countries have shown interest in small modular reactors (SMRs) as a potential energy source, this interest can generate new uncertainties regarding future nuclear weapons proliferation risks. Therefore, this research seeks to determine whether future SMR deployment in NEN countries will contribute to nuclear weapons proliferation, and how the risks can be mitigated. This research uses the Bayesian network statistical approach in conjunction with surveys of experts to assess nuclear proliferation risks when NEN countries deploy SMRs or a large commercial nuclear reactor. The results indicate that an NEN with a strong commitment to the nuclear non-proliferation norms and a stable security environment will experience a lower probability of having higher proliferation risks relative to the United Arab Emirates. Specifically, we demonstrate that experts anticipate a minimal escalation in proliferation risks across different SMR types. Instead, the results show that enrichment or reprocessing (E&R) facilities, if associated with an SMR, exert a substantial influence on proliferation risks. Lastly, implementing a spent nuclear fuel (SNF) retrieval system could serve as an option to mitigate proliferation risks in an NEN country. These findings offer insights for leading nuclear supplier countries to alleviate the potential proliferation risks by NEN countries.

• 한국전자거래학회지
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• 제25권1호
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• pp.177-202
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• 2020

본 연구는 세계 무기 수출 시장의 구조적인 변화 요인을 식별하기 위한 통계적 모형을 설계하고 실증 분석 결과와 경제적 함의를 제시하고자 한다. 무기 수출의 변화 양상을 설명할 수 있는 변인은 무엇인가, 그러한 변화는 통계적으로 유의한가, 변화의 특성은 어떻게 해석될 수 있는지를 중심으로 연구 질문을 삼고 분석의 틀을 설계하였다. 실증 분석을 위해 SIPRI 데이터베이스에 수록된 무기 수출 상위 40개 국가의 거래량을 분석 대상으로 삼았다. 그리고 연구 모형을 설정하기 위한 가설을 제시하고 가설로부터 도출된 변수들의 조합에 따라 여러 회귀 모형을 구성하여 통계적 유의성을 검증하였다. 분석 결과에서 국가 보유고 변수는 무기 수출 시장의 변화와 지속적인 관계를 맺고 있는 변수로서 특징적인 의미를 보여주고 있으며, UN 안보리 상임이사국 그룹은 세계 무기 수출에 집단적인 지배력을 발휘하고 있는 것으로 나타났다. 이와 함께 2000년대를 전후로 하여 나타난 변화의 주요 동인은 국내 총생산과 국가 순 수출액과 관련이 있는 것으로 파악되었다. 전반적으로 이런 요인들이 세계 무기 수출의 흐름과 방향을 좌우해왔던 것으로 평가되며 향후에도 무기 수출 시장의 구조에 영향을 주는 변수가 될 것으로 전망된다.

• Nuclear Engineering and Technology
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• 제56권9호
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• pp.3804-3811
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• 2024

The study focuses on creating new boro-silicate glasses doped with SnO₂ for radiation shielding. It examines how substituting Na₂O with SnO₂ affects their structural, optical, and shielding properties. Density increases from 2.406 to 2.488 g/cm³ with rising SnO₂, measured via the Archimedes Method. The examination for the glassy phase was performed using the XRD diffractometer. UV/Vis spectrophotometer analysis reveals reduced refractive index (2.412-1.976) and increased optical absorption-band gap (direct: 3.648-5.662 eV; indirect: 2.994-5.163 eV) with SnO₂ concentrations of 0-9 mol.%). The effectiveness of the radiation shielding was assessed over the 0.059-1.408 MeV gamma-ray energy interval. The analysis demonstrates that when the concentration of SnO₂ increases, the synthesized glasses' linear attenuation coefficient improves. As the SnO₂ content was raised between 0 and 9 mol%, the linear attenuation coefficient rose between 0.489 and 2.892 cm^-1 (at energy of 0.059 MeV) and between 0.126 and 0.128 cm^-1 (at energy of 1.408 MeV), respectively. As the SnO₂ content was raised between 0 and 9 mol%.

• 한국전자거래학회지
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• 제19권4호
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• pp.1-19
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• 2014

빅데이터 내에 존재하는 감정 정보를 추출하여 사용자들이 특정 대상에 대하여 갖고 있는 인식이 어떠한지를 파악하고자 하는 노력이 활발히 이루어지고 있다. 상품, 영화, 그리고 사회적 이슈 등에 대한 문장을 분석하여 사람들이 해당 주제에 어떠한 견해를 가지고 있는지를 분석하고 측정하여 구체적인 선호도를 알아내는 것이다. 문장에서 드러나는 감정 정도를 얻기 위해서는 감정어휘의 목록과 정도값을 제시할 수 있는 감정어휘사전이 필요하므로 본 연구에서는 감정어휘를 발견하는 방법과 이들의 정도값을 결정하는 문제를 다룬다. 기본적인 방법은 기초 감정어휘의 목록 수집과 이들의 정도값은 선행연구 결과와 직접 설문 방식을 이용하고, 확장된 목록의 수집과 정도값은 사전의 표제어 설명부(glosses)를 이용해 추론하는 것이다. 그 결과 발견된 감정어휘는 전형성을 띠고 있는 기본형 감정어휘, 기본형 감정어휘의 gloss에 사용된 확장형 1단계 1층위 감정어휘, 비 감정어휘 중 gloss에 기본형 또는 확장형 감정어휘를 가지고 있는 확장형 2단계 1층위 감정어휘, gloss의 gloss에 기본형 또는 확장형 감정어휘가 사용된 확장형 2단계 2층위 감정어휘의 네 종류로 나뉜다. 그리고 확장형 감정어휘의 정도값은 기본형 감정어휘의 정도값을 기초로 문형의 가중치와 강조승수를 적용하여 얻었다. 실험 결과 AND, OR 문형은 내포된 어휘의 감정 정도값을 평균내는 가중치를, Multiply 문형은 정도 부사어의 종류에 따라 1.2~1.5의 가중치를 갖는 것으로 파악되었다. 또한 NOT 문형은 사용된 어휘의 감정 정도를 일정 정도로 낮추어 역전시키는 것으로 추정된다. 또한 확장형 어휘에 적용되는 강조승수는 1층위에서 2, 2층위에서 3을 갖는 것으로 예상된다.

• Nuclear Engineering and Technology
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• 제46권6호
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• pp.803-816
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• 2014

Defense-in-depth is a fundamental safety principle for the design and operation of nuclear power plants. Despite its general appeal, defense-in-depth is not without its drawbacks, which include its potential for concealing the occurrence of hazardous states in a system, and more generally rendering the latter more opaque for its operators and managers, thus resulting in safety blind spots. This in turn translates into a shrinking of the time window available for operators to identify an unfolding hazardous condition or situation and intervene to abate it. To prevent this drawback from materializing, we propose in this work a novel safety principle termed "observability-in-depth". We characterize it as the set of provisions technical, operational, and organizational designed to enable the monitoring and identification of emerging hazardous conditions and accident pathogens in real-time and over different time-scales. Observability-in-depth also requires the monitoring of conditions of all safety barriers that implement defense-in-depth; and in so doing it supports sensemaking of identified hazardous conditions, and the understanding of potential accident sequences that might follow (how they can propagate). Observability-in-depth is thus an information-centric principle, and its importance in accident prevention is in the value of the information it provides and actions or safety interventions it spurs. We examine several "event reports" from the U.S. Nuclear Regulatory Commission database, which illustrate specific instances of violation of the observability-in-depth safety principle and the consequences that followed (e.g., unmonitored releases and loss of containments). We also revisit the Three Mile Island accident in light of the proposed principle, and identify causes and consequences of the lack of observability-in-depth related to this accident sequence. We illustrate both the benefits of adopting the observability-in-depth safety principle and the adverse consequences when this principle is violated or not implemented. This work constitutes a first step in the development of the observability-in-depth safety principle, and we hope this effort invites other researchers and safety professionals to further explore and develop this principle and its implementation.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.110-116
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• 2022

Human failure event (HFE) dependency analysis is a part of human reliability analysis (HRA). For efficient HFE dependency analysis, a maximum number of minimal cut sets (MCSs) that have HFE combinations are generated from the fault trees for the probabilistic safety assessment (PSA) of nuclear power plants (NPPs). After collecting potential HFE combinations, dependency levels of subsequent HFEs on the preceding HFEs in each MCS are analyzed and assigned as conditional probabilities. Then, HFE recovery is performed to reflect these conditional probabilities in MCSs by modifying MCSs. Inappropriate HFE dependency analysis and HFE recovery might lead to an inaccurate core damage frequency (CDF). Using the above process, HFE recovery is performed on MCSs that are generated with a non-zero truncation limit, where many MCSs that have HFE combinations are truncated. As a result, the resultant CDF might be underestimated. In this paper, a new method is suggested to incorporate HFE recovery into the MCS generation stage. Compared to the current approach with a separate HFE recovery after MCS generation, this new method can (1) reduce the total time and burden for MCS generation and HFE recovery, (2) prevent the truncation of MCSs that have dependent HFEs, and (3) avoid CDF underestimation. This new method is a simple but very effective means of performing MCS generation and HFE recovery simultaneously and improving CDF accuracy. The effectiveness and strength of the new method are clearly demonstrated and discussed with fault trees and HFE combinations that have joint probabilities.

• 마케팅과학연구
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• 제13권
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• pp.113-133
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• 2004

본 논문은 인터넷의 이용의도를 형성하는데 있어서 구직활동 태도에 대한 지각된 요소의 역할을 객관적으로 조사하고자 하였다 이에 대한 연구모델로 Davis의 TAM의 두가지 측면 즉 지각된 유용성과 지각된 용이성에 대한 경험적 연구가 이루어 졌으며 실증적으로 검증하였다. 특히, 인터넷 구적효능감 또는 추어진 목표를 성취하기 위해 요구되는 인터넷 활동을 실행하거나 조직화하는데 있어서 자신의 능력에 대한 믿음은 인터넷을 이용하는데 대한 보다 호의적 태도를 얻는데 영향을 주는 중요한 요소이다. 수집된 자료의 분석과 연구모형 검증은 회귀분석을 통해 모형의 구성개념간 이론적 인과관계와 측정지표를 통한 경험적 인과관계를 종합적으로 분석할 수 있는 AMOS 통계처리 도구활 이용하였으며 인터넷의 구직효능감에 대한 내적 일관성과 신뢰성이 확인되었다. 또한 많은 과거 연구결과에서도 지각된 유용성이 정보기술의 이용행동에 과 이용자의 수용성에 중요한 영향을 끼친 것으로 나타났으나 시간에 따라 어떻게 지각이 형성되고 변화되는지에 대한 연구는 거의 이루어지지 않았다. 본 연구에서는 인지된 유용성에 대해 영향을 미치는 결정계수들을 확인하였다. 연구 결과에 따르며 인터넷상에서 보다 높은 구직효능감이 지각된 유용성 뿐만아니라 이용의도 및 성과에 긍정적인 영향을 끼친다는 사실을 확인하였다.