• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2015년도 제46회 하계학술대회
• /
• pp.292-293
• /
• 2015

전력수요의 증가 및 대규모 발전단지의 확장, 송 배전설비 확충의 어려움으로 계통이 복잡해지고 광역 정전 발생의 가능성이 증가하고 있다. 광역 정전 발생 시, 이로 인해 발생할 경제적 손실, 사회전반에 파급될 결과와 영향은 심각한 수준이므로 신속하고 안전한 복구방안의 수립이 중요하다. 또한 신속한 계통복구를 위해 정전 시 복구가능시간을 산정하고, 계통복구절차 방안을 제시하는 것이 중요하다. 우리 나라 계통복구절차를 보면 최초정전상태평가, 발전기상태평가, 계통복구방법 선택, 부하복구를 통한 정전복구 단계로 나눠볼 수 있다. 발전기상태 평가 단계에서 발전기들의 상태를 파악한 후, 기동순서를 결정한다. 본 논문에서는 광역정전 시 발전기 특성을 고려한 전력계통 복구를 위한 수학적 정식화를 하고 향후 연구 방향을 살펴보았다.

• 한국마린엔지니어링학회:학술대회논문집
• /
• 한국마린엔지니어링학회 2012년도 전기공동학술대회 논문집
• /
• pp.155-156
• /
• 2012

In the modern age, as man's demand of energy is continuously grew, tidal becomes one of the sustainable energy sources that have been investigating thoroughly recently. Tidal turbine has proved high potential as a future power-generating device. To effectively capture tidal energy on site, a group of tidal turbines should be used and positioned in some formation with proper size and space so that energy can be absorbed from multiple point. Thus, the turbines together with the flow filed becomes a huge domain, a tidal farm. So, it becomes more convenient if a whole turbine farm is simulated by means of actuator discs since the time and cost for analysis can be reduced. This paper aims to evaluate the operating performance (power efficiency and energy restoration rate), mutual influence (for different longitudinal and lateral spaces), the influence of velocity profiles, turbulence intensity and the far wake characteristic of tidal turbines operating in farm formation. The results of this study help contributing to the present development of tidal turbine as the future potential energy conversion machinery.

• 환경영향평가
• /
• 제20권5호
• /
• pp.663-673
• /
• 2011

In the face of accelerating biodiversity loss and its significance in our coexistence with nature, biodiversity is becoming more crucial in sustainable development perspective. To estimate biodiversity in the future which provides valuable information for decision making system especially in the national level, a quantitative approach must be studied forehand as a baseline of the present status. In this study, we developed a large-scale map of Plant Species Richness (PSR, typical indicator of biodiversity) for Young-dong and Pyung-chang provinces. Due to the accessibility of appropriate data and advance of modelling techniques, reduction of variables without deteriorating the predictive power is considered by applying Genetic algorithm. In addition, a number of Correctly Classified Instances (CCI) with 10-fold cross validation which indicates the predictive power, was carried out for evaluation. This study, as a fundamental baseline, will be beneficial in future land work as well as ecosystem restoration business or other relevant decision making agenda.

• 한국화재소방학회논문지
• /
• 제24권5호
• /
• pp.10-25
• /
• 2010

현대사회에서 재난의 잠재력이 커질수록 재난을 대비하고 대응하는 국가의 체계를 보다 효율적으로 개선하고 강화하기 위하여 재난관리담당부서에서 근무하는 공무원을 대상으로 설문을 받아 분석하였다. 이 연구에서 알아보고자 한 내용은 다음과 같다. 첫째, 재난관리 기관 간 협력관계, 둘째, 재난관련법 제정 및 재난전담부서의 필요성 셋째, 재난관리 상황적 변수에 대한 인식으로 재난관리 상황요인에 대한 전반적 인식, 재난유형에 대한 전반적 인식, 재난규모에 따른 발생가능성에 대한 인식, 넷째, 재난관리의 구조적 변수에 대한 인식으로 재난관리에 대한 소방방재청, 유관기관, 지방자치단체의 인식 차이, 예방-대비-대응-복구단계의 혼선에 대한 인식에 대한 연구이다.

• Nuclear Engineering and Technology
• /
• 제52권5호
• /
• pp.964-974
• /
• 2020

The small modular reactors (SMRs) of the integrated pressurized water reactor (IPWR) type have been widely developed owing to their enhanced safety features. The SMR-IPWR adopts passive residual heat removal system (PRHRS) to extract residual heat from the core. Because the PRHRS removes the residual heat using the latent heat of the water stored in the emergency cooldown tank, the PRHRS gradually loses its cooling capacity after the stored water is depleted. A quick restoration of the power supply is expected infeasible under station blackout accident condition, so an advanced PRHRS is needed to ensure an extended grace period. In this study, an advanced design is proposed to indirectly incorporate a dry air cooling tower to the PRHRS through an intermediate loop called indefinite PRHRS. The feasibility of the indefinite PRHRS was assessed through a long-term transient simulation using the MARS-KS code. The indefinite PRHRS is expected to remove the residual heat without depleting the stored water. The effect of the environmental temperature on the indefinite PRHRS was confirmed by parametric analysis using comparative simulations with different environmental temperatures.

• 수산경영론집
• /
• 제36권3호
• /
• pp.1-24
• /
• 2005

Korean fishery wage system has been evolved with the different titles. However, Since the law of fishing crew was enacted in 1984, the fishery wage system has been established as a rate system, which is a legal term. The present rate system in practice shows various contents and modalities, depending on fisheries and regions, but the fisheries of large trawl cooperative employ a rate system of fixed plus rate wage. However, such change did not transform basically the properties of pure rate scheme. As well known, fishing vessel owners face an awful lot of difficulty in managing and controlling effectively the production process because fishing activities are carried out in the seas remote from the land. Thus, it tend to be inevitable for vessel owners to employ a rate system to induce fishermen's positive motivation for promoting productivity and saving operating costs. However, the rate system has worked out as a driving force, which induce an increase in production more strongly under the expansion of vessel numbers and power and the keener competition of fishing activities. Even though the control mechanism of fishing instruments are well established, fishermen become naturally to have an incentive to increase their fishing effort for maximizing production since they are able to raise their shares by maximizing the quantity harvested. Thus, as far as the rate system exists, fisheries administration may have much difficulty in realizing its fishery management goals only through vessel reduction and fishing gear regulations. Also, under the rate system fishery management authority may be in face of a serious dilemma between the spontaneous rate system and vessel reduction policy. If the realistic aspect of the rate system is recognized and resource restoration and profit promotion are main policy goals, it is necessary to develop effective ways to control vessel owners' and fishermen's production-maximizing motives at an appropriate level. From this point of view, it seems reasonable to introduce TAC system by species or by fisheries into the existing fishery system. The research results suggest that if the fisheries administration could understand clearly the spontaneous fisheries wage system, it would know the norm of TAC and the basic reasons for illegal fishing activities and thus it would be able to develop and implement more realistic resource management policies.

• 한국방사선학회논문지
• /
• 제12권2호
• /
• pp.139-148
• /
• 2018

원전의 안전한 해체 관리를 위해 원전 해체 비용 평가는 매우 중요하다. 가장 많은 원전 해체 경험을 갖고 있는 미국의 경우 1970년대부터 원자력시설의 해체를 위하여 비용평가 연구를 진행하였다. 미국 NRC는 다양한 로형 및 원자력시설에 대한 해체 기술, 안전성 및 비용에 대한 연구를 수행하였다. 전체 해체 비용에서 운영허가종료비용이 가장 큰 비중을 차지하며, 그 다음으로는 사용후핵연료 관리, 부지복원순으로 평가되었다. 해체비용은 전체비용에 있어 운영허가종료가 제일 큰 비중을 차지하며 사용후핵연료관리, 부지복원 순으로 평가되었다. 즉시해체의 경우 지연해체에 비해 사용후핵연료관리 비용이 증가하였으며 지연해체의 경우 운영허가종료의 비용이 증가하였다. 전반적으로 즉시해체에 비해 지연해체의 경우가 뚜렷하게 이득이 보이지 않고 있다. 국내 원전 해체 비용 평가시 부지 조건에 따른 평가를 고려해야할 필요가 있다고 판단된다. 또한 국내의 경우 IAEA의 권고사항을 적용하여 방사성폐기물 분류체계를 재정비하였다. 이에 따라 해체시 발생하는 방사성폐기물 물량 산정시, 선행 미국 원전해체 자료를 신분류체계에 적합하게 활용하기 위한 방법을 개발해야할 필요가 있다. 특히 자체처분 대상폐기물 평가 방법론 설정은 해체비용의 정확성을 확보하는 중요한 인자로 작용할 것이다. 또한 국내 원전해체 비용 평가를 위하여 시설 특성과 작업 특성에 적용할 수 있는 정보자료 구축이 필요하다.

• 한국전자파학회논문지
• /
• 제18권8호
• /
• pp.970-976
• /
• 2007

본 논문에서는 2비트 시그마-델타 변조기를 도입한 새로운 구조의 폴라 트랜스미터에 대해 논의한다. 제안된 구조에서는 2비트 시그마-델타 변조 방식을 도입하여 양자화 잡음을 낮추도록 하였다. 전력 증폭기는 2비트 디지털 처리된 진폭 신호를 받아들이기 위하여 2진법의 형태로 분할되도록 고안되었다. 새로운 구조의 폴라 트랜스미터를 EDGE 시스템에 적용하여 시뮬레이션 한 결과, 전체 전송 대역에서 스펙트럼 특성이 개선되는 것을 확인할 수 있었다. 2비트 변조기에 세밀한 양자화 방식을 적용함으로써 오버 샘플링 비가 2배 이상 증가한 정도의 잡음 감소 특성을 얻을 수 있었고 오버 샘플링 비를 증가시키지 않고도, 트랜스미터 출력 신호의 주파수 잡음을 10dB 이상 낮출 수 있었다. 또한, 전력 증폭기를 2진법으로 분할한 결과 다이나믹 영역이 5dB 정도까지 증가하는 효과를 얻었다.

• 전기학회논문지
• /
• 제62권6호
• /
• pp.744-749
• /
• 2013

The protection switching technology is widely adopted in the fiber-optical transmission equipments based on TDM(Time Division Multiplexing), such as PDH, SDH/SONET. A variety of protection switching algorithms for Ethernet networks and the progress of standardization are summarized in the document. There are several kinds of protection switching algorithms for Ethernet networks, such as STP, RSTP, MSTP and etc. However, since Ethernet signal move through detour route, it causes much time to recover. Accordingly, it is difficult to secure a usability of Ethernet networks and QOS(Quality of Service). Also, if the protection switching protocol standardized by IEEE and ITU-T is used, it remains a inherent network switching time for protection. Therefore, a specific protection switching algorithm for Ethernet are needed for seamless and stable operation of Ethernet networks service for Distribution Automation System(DAS). A reliable protection algorithm with no switching delay time is very important to implement Self-healing service for DAS. This study of FPGA based protection switching algorithm for Ethernet networks shows that in case of faults occurrence on distribution power network, immediate fault isolation and restoration are conducted through interaction with distribution equipments using P2P(Peer to Peer) communication for protection coordination. It is concluded that FPGA based protection switching algorithm for Ethernet networks available 0ms switching time is crucial technology to secure reliability of DAS.

• 대한간호학회지
• /
• 제39권6호
• /
• pp.788-795
• /
• 2009

Purpose: The purpose of this study was to define and clarify the concept of 'resilience' in patients with cardiovascular diseases. Methods: A hybrid model was used to develop the concept of resilience. The model included a field study carried out in Cheonan, Korea. The participants in this study were 9 patients with cardiovascular diseases who underwent a percutaneous coronary intervention. Results: The concept of resilience was found to be a complex phenomenon having meanings in two dimensions: the personal-dispositional and interpersonal dimensions. Four attributes and seven indicators were defined. Conclusion: A resilient person was defined as one who has a positive attitude toward restoration, the power to reconstruct and control his/her disease (personal dimension), and support from a supportive system with supportive persons (interpersonal dimension). In the clinical setting, resilience plays an important role in managing the care plans of cardiovascular patients. Therefore, nurses who work closely with patients suffering from cardiovascular diseases should be aware of the attributes and indicators of resilience to enhance the resilience of their patients.