• 한국컴퓨터정보학회논문지
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• 제10권4호
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• pp.345-354
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• 2005

본 논문에서는 웹 기반 분산 기업 시스템 사이의 협력을 분석하여 적기 협력의 필요성을 파악하였고 이를 기업 사이의 계약 관점에서 기술하였다. 그리고 이러한 기업 시스템 사이의 적기 협력을 지원할 수 있는 ECA(event condition action) 규칙 기반 방안과 이 방안을 지원하는 능동 기능 컴포넌트(AFC)를 제안한다. 제안된 방안은 고수준의 ECA 규칙 프로그래밍과 사건 기반의 즉시 처리 방식을 지원하므로 시스템 관리자나 프로그래머가 응용 로직과는 별도로 적기 협력을 쉽게 구축하고 유지 보수할 수 있다. 제안하는 능동 기능 컴포넌트는 기업의 방화벽을 통해서도 적용될 수 있도록 HTTP 프로토콜을 사용하였고, 실용성을 위하여 상업용 DBMS의 기본 트리거를 이용하여 구현하였다.

• 대한조선학회논문집
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• 제50권5호
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• pp.334-342
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• 2013

In this paper, we analyze the procedure of the design manager for the enhancement of the hull production design process by use of the simulation method. Normally, design manager assigns design jobs according to various methods and estimates the corresponding results. When the construction drawing which is the output of the detail design where a design is dealt by zones, the design manager identifies blocks and analyzes their work difficulties, and assigns jobs to design engineers who are different in capabilities. These processes including the design engineer who can be modeled with man-hours evaluation model are represented in detail as a simulation model. As the high-level modeling for the discrete-event system, we use Event Graph model. And we implemented the simulation using Simkit which is open simulation engine for the discrete-event system. We made the simulation scenario to be written by a user in the scenario generator which is separated from the simulation model, and made the simulation result to be visualized in the form of Gantt chart in a Web. In the scenario of the irregular issuance for various construction drawings which contain different numbers of blocks, we performed the Monte-Carlo simulation according to various assignment methods to find the assignment result that satisfies the mid-term schedule.

• Nuclear Engineering and Technology
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• 제31권5호
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• pp.476-485
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• 1999

In order to evaluate the gravity-injection capability to maintain core cooling after a loss-of-shutdown-cooling event during shutdown operation, the plant conditions of the Yong Gwang Units 3&4 were reviewed. The six cases of possible gravity-injection paths from the refueling water tank (RWT) were identified and the thermal-hydraulic analyses were performed using the RELAP5/MOD3.2 code. The core cooling capability was significantly dependent on the gravity-injection path, the RCS opening, and the injection rate. In the cases with the pressurizer manway opening higher than the RWT water level, the coolant was held up in the pressurizer and the system pressure continued increasing after gravity-injection. The gravity injection eventually stopped due to the high system pressure and the core was uncovered. In the cases with the injection path and opening on the same leg side, the core cooling was dependent on whether the water injected from the RWT passed the core region or not. However, in the cases with the injection path and opening on the different leg side, the system was well depressurized after gravity-injection and the core boiling was successfully prevented for a long-term transient. In addition, from the sensitivity study on the gravity-injection flow rate, it was found that about 54 kg/s of injection rate was required to maintain the core cooling and the core cooling could be provided for about 10.6 hours after event with that injection rate from the RWT. Those analysis results would provide useful information to operators coping with the event.

• 한국가스학회지
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• 제14권5호
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• pp.38-44
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• 2010

본 논문은 철도를 통해 운송되는 프로필렌의 사고위험을 정량적으로 분석하였다. 프로필렌의 수송 경로에 따라 사고 시 피해 위험이 높을 것으로 예상되는 지역인 익산역, 순천역, 전주역으로 대상지역을 선정하였다. 프로필렌의 운송 중 일어날 수 있는 사고유형을 고려한 후 ETA(Event Tree Analysis)를 이용하여 사고시나리오 및 발생빈도를 도출하였고, PHAST 6.53(Process Hazard Analysis Software Tool)을 이용하여 사고피해예측 평가 실시하여 주변에 미치는 피해정도를 산정함으로써 개인적.사회적 위험성정도를 제시하였다.

• 한국자동차공학회논문집
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• 제11권2호
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• pp.148-156
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• 2003

Many car manufacturers have frequently adopted an aggressive inflator and a lower threshold speed for airbag deployment in order to meet an injury requirement for unbolted occupant at high speed crash test. Consequently, today's occupant safety restraint system has a weakness due to an airbag induced injury at low speed crash event. This paper proposes a new crash algorithm to improve the weakness by suppressing airbag deployment at low speed crash event in case of belted condition. The proposed algorithm consists of two major blocks-crash severity algorithm and deployment logic block. The first block decides crash severity with two levels by means of velocity and crash energy calculation from acceleration signal. The second block implemented by simple AND/OR logic combines the crash severity level and seat belt status information to generate firing commands for airbag and belt pretensioner. Furthermore, it can be extended to adopt additional sensor information from passenger presence detection sensor and safing sensor. A simulation using real crash data for a 1,800cc passenger vehicle has been conducted to verify the performance of proposed algorithm.

• 대한의용생체공학회:의공학회지
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• 제43권1호
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• pp.52-60
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• 2022

Purpose: For now, cognitive load is assessed based on survey-based methods, which can be difficult to track the amount of cognitive load in real-time. In this study, we investigated the difference in electrophysiological activation due to different levels of cognitive load not only at sensor-level but also at source-level using electroencephalogram that might be potentially used for quantitative cognitive load evaluation. Materials and Methods: In this study, ten healthy subjects (mean age 24.3 ± 2.1, three female) participated the experiment. All participants performed 4 sessions of n-back task in different difficulties: 0-, 1-, 2-, and 3-back during electroencephalogram recording. For sensor-level analysis, we calculated the event-related potential and event-related spectral perturbation while low resolution brain electromagnetic tomography (LORETA) to estimate the source activation. Each result was compared between different workload conditions using statistical analysis. Results: Statistical results revealed that the accuracy of the task performance was significantly different between different cognitive loads (p = 0.018). The post-hoc analysis confirmed that the accuracy of the 3-back task was significantly decreased compared to 1-back condition (p = 0.018), but not with 2-back condition (p = 0.180). ERP results showed that P300 target amplitude between 1-back and 3-back had a marginal difference in Cz (p = 0.059) and Pz(p = 0.093). A significant inhibition in Cz high-beta activation (p = 0.017) and decrease in source activation of right parahippocampal gyrus was found in 3-back condition compared to 1-back condition (p < 0.05). Conclusion: In this study, we compared the sensor- and source-level differences in electroencephalogram between different levels of cognitive load, that were found to be in line with the previous reports related to cognitive load evaluation. We expect that the outcome of the current study can be used as a feature to establish a quantitative cognitive load assessment system.

• 한국노년학
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• 제28권4호
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• pp.969-989
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• 2008

본 연구는 노인의 우울감과 자살생각 간의 관계를 밝히고, 노인의 심리사회적 특성이 이들 관계를 조절하여주는지 살펴보기 위하여 실시되었다. 조사는 서울, 부산, 대구의 노인복지회관을 이용하는 65세 이상의 노인을 대상으로 진행되었으며 273명의 자료가 최종분석에 활용되었다. 조사도구로는 건강문제, 생활사건, 자존감, 가족의사소통 척도 등이 사용되었으며, 수집된 자료는 SPSS/PC+ 12.0을 사용하여 기술통계분석, 피어슨의 상관관계, 신뢰도 분석, 다중선형회귀분석, 일반선형모델 분석을 실시하였다. 연구결과 우울감과 심리사회적 특성의 수준이 높을수록 노인의 자살생각이 높은 것으로 나타났다. 그리고 심리사회적 특성의 하위요소 가운데 생활사건, 자존감, 가족의사소통과 노인의 자살생각 간의 관계에서 노인이 경험한 심리사회적 특성의 조절효과가 나타났다. 결론적으로 지역에 거주하는 노인의 심리사회적 특성의 하위요인들이 노인의 우울감과 자살생각에 영향을 미치는 것으로 나타났다. 이러한 결과는 자살생각을 감소시키는 효과적인 개입방법으로써 자긍심을 강화하고, 스트레스적인 생활사건과 가족불화에 대처할 수 있는 예방 전략으로 노인자살에 대한 위험요인을 줄일 수 있을 것이다.

• Nuclear Engineering and Technology
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• 제38권6호
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• pp.489-504
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• 2006

A review has been made for the previous studies on safety of a geologic repository for high-level radioactive wastes (HLW) related to autocatalytic criticality phenomena with positive reactivity feedback. Neutronic studies on geometric and materials configuration consisting of rock, water and thermally fissile materials and the radionuclide migration and accumulation studies were performed previously for the Yucca Mountain Repository and a hypothetical water-saturated repository for vitrified HLW. In either case, it was concluded that it would be highly unlikely for an autocatalytic criticality event to happen at a geologic repository. Remaining scenarios can be avoided by careful selection of a repository site, engineered-barrier design and conditioning of solidified HLW. Thus, criticality safety should be properly addressed in regulations and site selection criteria. The models developed for radiological safety assessment to obtain conservatively overestimated exposure dose rates to the public may not be used directly for the criticality safety assessment, where accumulated fissile materials mass needs to be conservatively overestimated. The models for criticality safety also require more careful treatment of geometry and heterogeneity in transport paths because a minimum critical mass is sensitive to geometry of fissile materials accumulation.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2002년도 추계학술대회 논문집
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• pp.79-83
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• 2002

High Level Architecture (HLA)는 이기종 시뮬레이터 간의 연동을 위한 미들웨어이다. 본 논문에서는 Discrete Event System Specification (DEVS) 형식론을 바탕으로 한 DEVS 모델의 시뮬레이션을 HLA 기반에서 수행하는 방법에 대하여 제시한다. DEVS 시뮬레이션 메시지를 HLA의 서비스를 사용하여 변환하여 기존의 시뮬레이션 알고리즘을 그대로 사용하여 분산 시뮬레이션 할 수 있는 방식에 대하여 기술한다. 또한 모델 사이의 연결 정보를 HLA 환경에서 이용하는 방식에 대하여 기술한다. 제안된 방식을 구현한 DEVSimHLA 시뮬레이션 환경의 구조 및 동작 방식에 대하여 알아보고 이를 이용한 간단한 예제를 보인다.

• 대한기계학회논문집B
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• 제21권3호
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• pp.427-435
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• 1997

Conditional sampling techniques are utilized to investigate the relation between the wall skin-friction and stream wise velocity fluctuations in a turbulent boundary layer. Conditionally averaged results using a peak detection and the VITA (variable-interval time-averaging) technique show that a high skin friction is associated with high frequency components of the wall skin-friction fluctuations. The conditionally averaged wall skin-friction fluctuations obtained by using the VITA technique have a positively-skewed characteristics compared with the conditionally averaged stream wise velocity fluctuations. It is confirmed that there exists a phase shift between the wall skin-friction and stream wise velocity fluctuations, which was also found from the long-time averaged space-time correlations. The amount of phase shift between the wall skin-friction and stream wise velocity fluctuations is the same as that from the long-time averaged space-time correlations and does not change despite the variation of the detection threshold.