• Nuclear Engineering and Technology
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• 제53권9호
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• pp.2888-2898
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• 2021

Vital area identification (VAI) is an essential procedure for the design of physical protection systems (PPSs) for nuclear power plants (NPPs). The purpose of PPS design is to protect vital areas. VAI has been improved continuously to overcome the shortcomings of previous VAI generations. In first-generation VAI, a sabotage fault tree was developed directly without reusing probabilistic safety assessment (PSA) results or information. In second-generation VAI, VAI model was constructed from all PSA event trees and fault trees. While in third-generation VAI, it was developed from the simplified PSA event trees and fault trees. While VAIs have been performed for NPPs in full-power operations, VAI for NPPs in low-power and shutdown (LPSD) operations has not been studied and performed, even though NPPs in LPSD operations are very vulnerable to sabotage due to the very crowded nature of NPP maintenance. This study is the first to research and apply VAI to LPSD operation of NPP. Here, the third-generation VAI method for full-power operation of NPP was adapted to the VAI of LPSD operation. In this study, LPSD VAI for a few plant operational states (POSs) was performed. Furthermore, the operation strategy of vital areas for both full-power and LPSD operations was discussed. The LPSD VAI method discussed in this paper can be easily applied to all POSs. The method and insights in this study can be important for future LPSD VAI that reflects various LPSD operational states. Regulatory bodies and electric utilities can take advantage of this LPSD VAI method.

• 한국터널지하공간학회 논문집
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• 제4권1호
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• pp.27-35
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• 2002

우리 나라 대부분의 토목현장에서는 암반의 굴착을 위하여 발파공법이 시행되고 있다. 발파공법은 기타 파암공법에 비하여 작업능률의 향상, 공사기간의 단축 등으로 많이 행해지고 있다. 그러나 발파작업은 발파진동, 발파소음, 비산 등으로 많은 피해를 발생하기도 한다. 따라서 본 연구에서는 미진동 공법 중에 하나인 플라즈마 공법의 특성, 파암효과 및 적용성에 대하여 검토해 보았다. 본 연구에서 나타난 플라즈마 공법에 의한 감쇠지수는 1.45~2.23이고 발파공법의 감쇠지수는 1.39~1.40으로 분석되었다. 그리고 시험파암 결과 파암지점과 계측지점과의 거리가 약 15m 이상인 지점부터는 대부분의 파암진동이 문화재나 컴퓨터 시설 등 민감한 보안물건에 대한 허용기준치인 0.2kine(cm/sec) 이내로 계측되었다. FFT(Fast Fourier Transform)분석 결과 당 현장에서 발파공법에 의해 계측된 주파수는 30~50Hz이고 플라즈마 공법의 주파수는 30~130Hz 사이에 분포하고 있다.

• Journal of Trauma and Injury
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• 제20권2호
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• pp.72-76
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• 2007

Purpose: The purpose of this clinical trial was to evaluate the fixation method for treating alveolar fractures in an emergency department. Methods: The efficiency of using the fixation method was judged on the basis of clinical criteria. Stability, occlusion state, bleeding amount after fixation, operation time, and difficulties during procedural operation were recorded. Results: Eight patients were enrolled in this study. In all instances, the fixation method was effective in bleeding control. Each patient had a noticeable decrement in bleeding. A wire was used for four of the eight patients, and nylon strings was used for the others. The average operation time was 6.3 minutes for the wire patients and 2.8 minutes for the Nylon string patients. No specific problem was identified during the procedural operation. However, the difference in the fixation material influenced the effectiveness of the procedure, the operation time, and the satisfaction of the doctor. Conclusion: In the emergency department, the fixation method using wire or nylon string in the treatment of alveolar fractures is effective in bleeding control

• 한국항행학회논문지
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• 제25권4호
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• pp.273-279
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• 2021

무인항공기에 적용되는 비행제어컴퓨터는 safety-critical 구성품으로, 내결함성을 확보함으로써 운용의 신뢰성을 높이기 위해 다중화 구조로 설계되고 있다. 이러한 다중화 구조가 적용된 비행제어컴퓨터는 각각의 독립적인 연산/제어 장치가 동일한 시점에 동일한 작업을 수행할 수 있도록 설계되어야 하며, 이를 위해 각 연산/제어 장치 간의 작업 동기화를 위한 동기화 알고리즘이 포함되어야 한다. 본 논문에서는 무인기에 적용되는 이중화 비행제어컴퓨터간의 동기화를 위한 소프트웨어 설계 방법을 제안한다. 제안하는 동기화 방법은 고장률 감소를 위해 최소의 하드웨어 리소스만을 사용하여 동기화할 수 있도록 설계하였고, 동기화에 사용되는 하드웨어 타이머의 동작 방식을 고려하여 설계함으로써 타이머 동작에 따른 동기화 오차를 최소화 할 수 있도록 설계하였다.

• 전력전자학회논문지
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• 제5권2호
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• pp.184-191
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• 2000

기존의 2개의 컨버터를 병렬 운전하기 위해서는 2개의 변류기 (CT)가 필요하였으나, 본 논문에서는 1개의 변류기만으로도 2개의 컨버터를 병렬 운전 가능한 단일 전류센서 방식의 마스터-슬레이브 운전 방법을 제안하였다. 제안된 단일 전류센서 방식의 부하 전류 분배 성능을 확인하기 위하여, 2개의 컨버터를 설계, 제작하였고 기존방법 (예: 최대 전류법)과 부하 전류 분배 성능을 세 가지의 임의 조건하에서 시뮬레이션, 부하 실험을 통하여 비교하였다. 실험 결과 컨버터 2대를 병렬 운전하는 경우, 기존의 방법으로는 2개의 CT가 필요하였으나 제안한 단일 전류센서 방식을 이용한면 1개의 CT만으로도 부하 전류 분배가 잘 이루어짐을 확인할 수 있었다.

• 한국수자원학회논문집
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• 제46권12호
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• pp.1141-1155
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• 2013

최근에 이르러 기후변화에 따른 급격한 지구온난화에 대비하기 위해 많은 연구가 수행되고 있으며, 본 연구에서는 임하-안동댐 유역을 대상으로 미래 유량 변화에 대응하기 위한 다목적댐 운영 전략에 관하여 연구하였다. 미래 유량 전망결과를 이용하여 댐군을 연계운영하고 그 영향을 단독 댐 운영방법과 비교하여 평가하였다. 먼저 기후변화의 불확실성을 고려하기 위해 GCM와 통계학적 축소화 기법인 일기발생기 LARS-WG, 유출전망 모형abcd에 적용하여 미래 전망 댐 유입량을 산정하였다. 수위운영방법이 기존 댐운영방법에 대한 모의로 선정되었으며, 대안으로서 New York City rule을 적용한 선형계획법의 댐군 연계운영 모형을 적용하였다. 미래 유입량 전망결과는 과거의 연 총 유입량에 비하여 안동댐에서 평균72.81%, 임하댐에서 평균 65.65%감소하였다. 미래 유입량 전망자료를 댐 운영모형에 적용한 결과, 연계운영한 결과의 신뢰도가 평균 62.22%로 단독 운영 결과의 신뢰도 47.55%에 비해 GCM 종류에 상관없이 전반적으로 높았다. 특히 수량부족으로 인해 신뢰도가 낮은 경우, 편차는 더 크게 나타났다. 따라서 안동-임하 댐군에 연계운영을 적용하는 것이 상대적으로 기후변화에 따른 수량의 변화에 더 효율적으로 대응할 수 있음을 확인하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1428-1432
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• 2007

One of the most important targets of transportation is to transport human and commodities to the destination safely. Railway has low risk, compared with land, ocean and flight route and it assures high security as well as high speed driving, since it runs on regular track. However, train accident may result in tragic accident due to small carelessness, so special event recorder is preferably used in order for clarity of responsibility in case of accident, maintenance of signal device and defect analysis. JRU(Juridical Recorder Unit) for ATC/ATS/ATP can be more advanced event recorder. Event recorder of KTX-I which is running now is installed one by one on each leading car and last car, and operation plan of event recorder in case of single trainset is suggested. But regarding train operation of multi-coupled trainset operation such as KTX-II, more detailed study is required for event recorder revitalization and record data process method. Therefore, this research aims at operation plan used in existing event recorder, and suggests effective operation and management plan of event recorder in multi-coupled trainset such as new High Speed Train.

• Journal of Chest Surgery
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• 제32권10호
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• pp.930-934
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• 1999

Background: The purpose of this study is to analyze the clinical results ad operative compatability by Ravitch methods with pectus excavatum. Material and Method: From 1984 to 1997, were performed Ravitch operations in 40 patients of pectus excavatum and analyzed the effects of correction and postoperative complication according to time of operation retrospectively. The group comprised 35 mem and women whose mean age was 8.9$\pm$7.9 years(between 2 to 35 years). All patients had corrected with Ravitch operation or its modified operation. Modified fixations were accomplished with K-wire in 15 patients and internal plate in 2 and the materials were removed 3 months after operation. The result of correction was estimated with the degree of changed distance between inner surface of sternal body and vertebral in 3 months after correction. Result: Postoperative complications were wound disruption in 14 patients. Estimated distances after correction ranged 0.4 cm to 4 cm. The acceptability for chest wall correction was high(6 excellent, 29 good in criteria of Humphreys). Conclusion: We concluded that the benefits of Ravitch operation were a high acceptability of patients and their family, and sufficient correction with no specific complications related operation.

• 전기학회논문지
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• 제65권3호
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• pp.397-403
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• 2016

Generally, an electrical distribution configuration is a radial system with one-way current in a distribution management system (DMS). All feeders in a DMS have tie-switches to make radial system. Sometimes, DMS should change a tie-switch for operation. In that case, the tie-switch has to be closed first; then a switch is opened as another tie-switch in order to prevent blackout for customers. At the moment when the tie-switch is closed, distribution system is operated in a loop state, not radial. Before the loop operation, DMS operator has to check any expected events for stable distribution system operation; and the most important event is a mis-operation of a protection relay. In addition, DMS operator should check voltage profile violation but a calculation method of section voltages had not been used. Thus, this paper proposes a calculation method of section voltages at a loop operation in a DMS. The proposed calculation algorithm is verified by Matlap Simulink.

• 전기학회논문지
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• 제67권9호
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• pp.1152-1158
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• 2018

In this paper, Optimal operation plan through load analysis of industrial end-user is suggested. It calculated economic feasibility of ESS with detailed power lad analysis and conditions. Generally, if the latest maximum power is less than 30% of contracted power, it can not be peak shaving operation plan. and if the peak load level stays stead for 24 hours, it is difficult peak shaving for ESS. In addition to, When the peak load is occurred in summer or winter, a hybrid operation method combining the peak shaving plan and the time shift method is proposed. Therefore, When ESS is installed in industrial electrical customer, it is achieved best effect through the optimal operation plan.