• 정보보호학회논문지
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• 제14권5호
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• pp.121-133
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• 2004

Okeya-Sakurai는 타원곡선 암호시스템에 대한 부채널 공격의 대응방법으로 소개된 Oswald-Aigner의 랜덤한 덧셈-뺄셈 체인(Randomized Automaton 1, 2) 대응방법 [18]이 SPA 공격에 취약함을 보였다$^{[15,16]}$. 그러나 본 논문에서는 Okeya-Sakurai의 공격 알고리즘 [15,16]에 두 가지 잠재된 문제가 있음을 보인다. 그리고 두 가지 문제점에 대한 해결책을 제시하고 [15,16,19]와는 다른 새로운 효율적인 공격 알고리즘을 제안한다. 표준에 제안되어 있는 163비트 비밀키를 사용하는 알고리즘에 본 논문의 분석방법을 적용해 구현한 결과, 단순한 형태의 랜덤한 덧셈-뺄셈 체인(Randomized Automaton 1)에서는 20개의 AD수열로 대략 94%의 확률로 공격이 성공하며 30개의 AD수열로는 대략 99%의 확률로 공격이 성공한다. 또한, 복잡한 형태(Randomized Automaton 2)에서는 40개의 AD수열로 94%의 확률로 70개의 AD수열로는 99%로의 확률로 공격이 성공한다.

• Archives of Plastic Surgery
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• 제48권3호
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• pp.287-292
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• 2021

Background We report the efficacy of a dual-plane approach using a Dufourmentel skin flap with a purse-string suture of the de-epithelized dermis to manage pseudoaneurysm at the vascular access site for hemodialysis. Methods A retrospective analysis was conducted of 61 patients from 2013 to 2018 with pseudoaneurysms at the arteriovenous fistula or graft who were treated with rhomboid excision, vessel repair with a purse-string suture, and a full-thickness Dufourmentel skin flap. The success rate was defined as the probability of complete wound closure and intact vascular access patency without infection or other complications. Results The success rate was 93.4% at 6 months postoperatively. Complications included newly occurring pseudoaneurysms (n=2), wound dehiscence (n=1) and bleeding (n=1). There were no complications such as stenosis or thrombosis from the procedure. Conclusions A dual-plane approach using a Dufourmentel skin flap with a purse-string suture for vessel repair was shown to be a favorable option for managing stable, small (diameter <2 cm) pseudoaneurysms without infection, rapid expansion, or patency issues of the vascular access.

• The Journal of Asian Finance, Economics and Business
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• 제7권10호
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• pp.303-313
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• 2020

This study investigates the factors affecting Industry 4.0 adoption in the curriculum of university students in Ho Chi Minh City, Vietnam. Universities need to respond to the changing faces of Industry 4.0 and, hence, Education 4.0. A mixed method including both qualitative and quantitative methodologies was utilized. An in-depth interview was carried out for exploring, reviewing, and testing content validity of constructs and measurement items. The pilot study was conducted with 120 respondents. The conceptual model and hypotheses were developed using data collected by a questionnaire survey distributed to 584 respondents by both electronic and paper forms with non-probability and convenience sampling techniques. The result of structural equation modeling showed that occupation relevance, skills, facility conditions, and social influence impacted on the intermediates variables, namely, relevance advantage, perceived usefulness, behavioral intention-to-use, and actual use. The independent variables are occupation relevance, skills, facility conditions, and social influence. They impact actual use through mediating constructs such as relevance advantage, perceived usefulness, and behavioral intention-to-use. The findings suggest that universities and students' efforts aimed at increasing the factors' perceptions of adoption of Industry 4.0 will contribute to implementation success, where success is defined as effectual usage of Industry 4.0.

• 한국군사과학기술학회지
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• 제25권4호
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• pp.412-424
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• 2022

Since traditional derivative-based optimization for noisy simulation shows bad performance, evolutionary algorithms are considered as substitutes. Especially in case when outputs are binary, more simulation trials are needed to get near-optimal solution since the outputs are discrete and have high and heterogeneous variance. In this paper, we propose a genetic algorithm called SARAGA which adopts dynamic resampling and fitness approximation using surrogate. SARAGA reduces unnecessary numbers of expensive simulations to estimate success probabilities estimated from binary simulation outputs. SARAGA allocates number of samples to each solution dynamically and sometimes approximates the fitness without additional expensive experiments. Experimental results show that this novel approach is effective and proper hyper parameter choice of surrogate and resampling can improve the performance of algorithm.

• 에너지공학
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• 제2권1호
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• pp.45-53
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• 1993

연료전지의 R&D 평가에 있어 현재의 불확실한 상황하에서 미래의 의사결정에 유용한 결과를 제공할 수 있는 방법론을 고찰해 보았다. 시뮬레이션을 이용한 사례연구는 기초 입력자료가 동일하다는 가정하에 일정상의 선후관계만을 고려한 경우(Case 1), 동등 및 배제 하위프로젝트를 고려한 경우(Case 2) 및 각 단계의 병렬수행을 허용한 경우(Case 3)에 대하여 수행하였으며, 이를 통하여 병행된 연구의 단계별 성공확률은 서로 상관관계를 갖고 있으며 각 프로젝트의 성공확률은 Case 1, Case 2, Case 3 순으로 향상되었고 상업화 성공시기는 Case 3 에서 현저하게 단축됨을 확인할 수 있었다.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1307-1313
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• 2019

Recent analysis results with realistic assumptions provide the variability of operator allowable time for the initiation of aggressive cooldown under small break loss of coolant accident or steam generator tube rupture with total failure of high pressure safety injection. We investigated how plant risk may vary depending on the variability of operators' failure probability of timely initiation of aggressive cooldown. Using a probabilistic safety assessment model of a nuclear power plant, we showed that plant risks had a linear relation with the failure probability of aggressive cooldown and could be reduced by up to 10% as aggressive cooldown is more reliably performed. For individual accident management, we found that core damage potential could be gradually reduced by up to 40.49% and 63.84% after a small break loss of coolant accident or a steam generator tube rupture, respectively. Based on the importance of timely initiation of aggressive cooldown by main control room operators within the success criteria, implications for improvement of emergency operating procedures are discussed. We recommend conducting further detailed analyses of aggressive cooldown, commensurate with its importance in reducing risks in nuclear power plants.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권9호
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• pp.3377-3395
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• 2015

Recently, several approaches to share road conditions and/or digital contents through VANETs have been proposed, and such approaches have generally considered the radial distance from the information source as well as the TTL to provision an ephemeral, geographically-limited information sharing service. However, they implement general MANETs and have not been tailored to the constrained movement of vehicles on roads that are mostly linear. In this paper, we propose a novel application-level mechanism that can be used to share road conditions, including accidents, detours and congestion, through a VANET. We assign probabilities to roads around each of the intersections in the neighborhood road network. We then use the graph representation of the road network to build a spanning tree of roads with the information source as the root node. Nodes below the root represent junctions, and the edges represent inter-connecting road segments. Messages propagate along the branches of the tree, and as the information propagates down the branches, the probability of replication decreases. The information is replicated until a threshold probability has been reached, and our method also ensures that messages are not delivered to irrelevant vehicles, independently of their proximity to the source. We evaluated the success rate and performance of this approach using NS-3 simulations, and we used IDM car following and MOBIL lane change models to provide realistic modeling of the vehicle mobility.

• International Journal of Computer Science & Network Security
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• 제21권8호
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• pp.28-34
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• 2021

Internet Service Providers (ISPs) constantly endeavor to resolve network congestion, in order to provide fast and cheap services to the customers. This study suggests two models based on Markov chain, using three and four access attempts to complete the call. It involves a comparative study of four models to check the relationship between Internet Access sharing traffic, and the possibility of network jamming. The first model is a Markov chain, based on call-by-call attempt, whereas the second is based on two attempts. Models III&IV suggested by the authors are based on the assumption of three and four attempts. The assessment reveals that sometimes by increasing the number of attempts for the same operator, the chances for the customers to complete the call, is also increased due to blocking probabilities. Three and four attempts express the actual relationship between traffic sharing and blocking probability based on Markov using MATLAB tools with initial probability values. The study reflects shouting results compared to I&II models using one and two attempts. The success ratio of the first model is 84.5%, and that of the second is 90.6% to complete the call, whereas models using three and four attempts have 94.95% and 95.12% respectively to complete the call.

• 한국시뮬레이션학회논문지
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• 제31권1호
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• pp.19-27
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• 2022

본 연구는 하나의 공급자와 하나의 소매자가 구성된 분산화된 공급사슬에서 도매가 계약과 수익공유 계약, 수량유연 계약, 판매환급 계약을 비교·분석한다. 선행 연구의 결과에 따라 공급사슬 조정(coordination)이 이루어지는 각 조정 계약의 모수를 설정하였다. 이들 모수의 조합에 대해 @RISK를 활용하여 시뮬레이션을 수행하고 공급사슬 조정을 이루는 상태 하에서 계약의 성사율과 각 계약에 유리한 참여자를 평가한다. 결과적으로 수량 유연 계약은 소매자 쪽에 가장 유리하고 판매환급 계약은 공급자 쪽에 가장 유리하다. 수익공유 계약은 공급자와 소매자의 이익 재배분에 가장 넓은 범위에서 선택할 수 있어 더 유연하게 사용할 수 있음을 밝혔다.

• 인터넷정보학회논문지
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• 제5권2호
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• pp.49-55
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• 2004

전자 우편을 이용함에 있어서 수신자의 전자 우편 주소 입력 시 오타 혹은 오기로 인해 발생할 수 있는 전자 우편 발송의 실패에 대해 수신자 실명을 표시하는 전자 우편 시스템 개발을 위한 방법을 연구하였다. 수신자 실명을 표시하는 전자 우편 시스템이란 전자 우편 자성 시 발송자가 입력하는 수신자의 전자 우편 주소를 통해 수신자의 실명을 데이터베이스를 통해 검색한 후 검색된 실명을 발송자에게 보여줌으로써 전자 우편의 발송확률을 높이는 시스템이다. 본 연구는 전자 우편의 발송 성공률과 데이터의 유출, 부정확한 전자 우편 발송에 따른 서버의 과부하와 이로 인한 경제적 손실을 최소화하는데 그 목적이 있다.