• International Journal of Air-Conditioning and Refrigeration
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• 제11권2호
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• pp.51-60
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• 2003

In the nuclear power plant, emergency core coolant system (ECCS) is furnished at reactor coolant system (RCS) in order to cool down high temperature water in case of emergency. However, in this coolant system, thermal stratification phenomenon can occur due to coolant leaking in the check valve. The thermal stratification produces excessive thermal stresses at the pipe wall so as to yield thermal fatigue crack (TFC) accident. In the present study, effects of turbulence penetration on the thermal stratification into T-branches with square cross-section in the modeled ECCS are analysed numerically. Standard k-$\varepsilon$ model is employed to calculate the Reynolds stresses in momentum equations. Results show that the length and strength of thermal stratification are primarily affected by the leak flow rate of coolant and the Reynolds number of duct. Turbulence penetration into the T-branch of ECCS shows two counteracting effects on the thermal stratification. Heat transport by turbulence penetration from main duct to leaking flow region may enhance thermal stratification while the turbulent diffusion may weaken it.

• 설비공학논문집
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• 제15권3호
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• pp.239-245
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• 2003

In the nuclear power plant, emergency core coolant system (ECCS) is furnished at reactor coolant system (RCS) in order to cool down high temperature water in case of emergency. However, in this coolant system, thermal stratification phenomenon can occur due to coolant leaking in the check valve. The thermal stratification produces excessive thermal stresses at the pipe wall so as to yield thermal fatigue crack (TFC) accident. In the present study, effects of turbulence penetration on the thermal stratification into T-branches with square cross-section in the modeled ECCS are analysed numerically. $textsc{k}$-$\varepsilon$ model is employed to calculate the Reynolds stresses in momentum equations. Results show that the length and strength of thermal stratification are primarily affected by the leak flow rate of coolant and the Reynolds number of the main flow in the duct. Turbulence penetration into the T-branch of ECCS shows two counteracting effects on the thermal stratification. Heat transport by turbulence penetration from the main duct to leaking flow region may enhance thermal stratification while the turbulent diffusion may weaken it.

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2008년도 국제학술회의
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• pp.33-41
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• 2008

The longest tunnel has been halted at Daekwanryung by the failure of the host country of the Winter Olympiad in 2014, but modern High-Power TBM will come to Korea to excavate these long tunnels to establish the better horizontal connection between the western and eastern countries to improve the strong powerful logistic strategy of Korean peninsula. Train operation provides a key function of air movements in a long underground tunnel, and heat generation from transit vehicles may account of the most heat release to the ventilation and emergency systems. This paper indicates the optimal fire suppress services and safety provision for the long railway tunnel which is designed twin tunnel with length 22km in Gangwon province of Korea. The design of the fire-fighting systems and emergency were prepared by the operation of the famous long-railway tunnels as well as the severe lessons from the real fires in domestic and overseas experiences. Designers should concentrate the optimal solution for passenger's safety at the emergency state when tunnel fires, train crush accidents, derailment, and etc. The optimal fire-extinguishing facilities for long railway tunnels are presented for better safety of the comfortable operation in this hard rock tunnel of eastern mountains side of Korea. Since year 1900, hard rock tunnel construction has been launched for railway tunnels in Korea, tunnels have been built for various purposes not only for infrastructure tunnels including roadway, railway, subway, and but also for water and power supply, for deposit food, waste, and oils etc. Most favorable railway tunnel system was discussed in details; twin tunnels, distance of cross passage, ventilation systems, for the comfortable train operations in the future.

• 대한조선학회논문집
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• 제54권4호
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• pp.301-311
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• 2017

Safety operational envelope (SOE) is the area which guarantees the safety of a submarine from the accident such as jamming and flooding. The maximum safe depth is set to prevent the damage to the hull from increasing water pressure with depth. A minimum safety depth is set to prevent a submarine from the exposure above the free surface and collision against surface ship. The prediction method for the SOE in the design phase is needed to operate the submarine safely. In this paper, the modeling and calculation methods of the SOE are introduced. Main ballast tank blowing modeling and propeller force modeling are conducted to simulate the accidents and the recovery process. The SOEs are established based on the crash stop and emergency rising maneuver simulation. From the simulation results, it can be known that the emergency rising maneuver is more effective recovery action than the crash stop.

• 대한임상독성학회지
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• 제21권2호
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• pp.151-155
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• 2023

Licorice is a perennial herb belonging to the legume family that mainly grows in northeastern China, Mongolia, Siberia, and other regions. It is used in traditional medicine in the form of dried roots in the East and the West. The main active component of licorice, glycyrrhizin, is known to produce mineralocorticoid effects when consumed chronically, which can lead to apparent mineralocorticoid excess syndrome. Herein, we present the case of a 72-year-old woman who was admitted to the emergency room with severe generalized weakness and difficulty keeping her neck upright, which had developed after daily consumption of licorice-infused water for the past 2 months. Blood tests revealed metabolic alkalosis and severe hypokalemia, and an electrocardiogram showed ventricular bigeminy. The patient was treated with daily potassium and spironolactone supplements, leading to a significant improvement in muscle strength after a week. One week later, the patient was discharged, showing rare ventricular premature contractions on electrocardiography, but with no specific complaints. Chronic licorice ingestion leading to hypokalemia and muscle weakness can be life-threatening, necessitating the discontinuation of the causative agent, close monitoring, and cautious supplementation of potassium and spironolactone as treatment.

• 한국수소및신에너지학회논문집
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• 제27권2호
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• pp.155-162
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• 2016

A proton exchange membrane fuel cell (PEMFC) produces only water at cathode by an electrochemical reaction between hydrogen and oxygen. The generated water is transported across the membrane from the cathode to the anode. The transported water collected in water-trap and drained to the cathode within the humidifier outlet. If the condensate water is not being drained at the appropriate time, condensate water in the anode can cause the performance degradation or fuel efficiency degradation of fuel cell by the anode flooding or unnecessary hydrogen discharge. In this study, we proposed an optimization method of condensate water drain logic for the water drain performance and the water drain algorithm as considered the condensate water generating speed prep emergency case. In conclusion, we developed the water management strategy of fuel processing system (FPS) as securing fuel efficiency and operating stability.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2006년도 학술발표회 논문집
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• pp.1726-1731
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• 2006

본 연구에서는 임하다목적댐의 비상여수로 설계를 위하여 수리모형실험과 수치모형실험을 수행하였다. 수치모의에는 3차원 수치모형인 FLOW-3D를 사용하였다. 비상여수로 설계를 위하여 접근수로부, 월류웨어부, 천이부 및 도류부, 그리고 감세부로 나누어 수리모형실험과 수치모형실험의 수리현상 결과를 비교하였다. 최적의 비상여수로 설계를 위하여 기본계획안에 대하여 모의하고 이에 대한 보완점과 문제점들을 찾아내고 해결책을 제시하였다. 수치모의를 통하여 수리모형실험에서 쉽게 수행하기 어려운 다양한 조건을 모의하고 최적의 결과에 찾아 이를 수리모형실험으로 검증함으로써 비상여수로 기본설계안을 도출하였다.

• Nuclear Engineering and Technology
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• 제26권2호
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• pp.161-167
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• 1994

본 논문은 비상노심냉각계통을 필요로 하지 않는 압력관형 피동 수냉각로 개념을 제시한다. 여기서는 사고시 핵연료에서 생성되는 열을 감속재로 효과적으로 전달시키기 위해 금속 핵연료 매트릭스를 사용하는 핵연료 채널을 채택한다. 정상 운전시에는 보통의 냉각재가 핵연료를 냉각시키지만, 냉각재상실사고를 포함하여 정상적인 냉각계통의 작동이 이루어지지 않을 경우에는 피동 감속재냉각계통에 의해 핵연료가 냉각된다. 유한요소 코드를 이용한 해석 결과, 정상 상태 및 사고시 핵연료 온도를 허용 한도 이내로 유지할 수 있는 것으로 나타났다.

• Nuclear Engineering and Technology
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• 제52권12호
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• pp.2847-2851
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• 2020

A simple water level measurement method based on wavelength division multiplexing (WDM) is proposed and demonstrated. The measurement principle is based on the change of Fresnel reflection occurring at the end facet of the optical fiber tip (OFT). To increase the spatial resolution of water level sensing, a broadband light source (BLS) and an arrayed waveguide grating (AWG) are employed. The OFTs are multiplexed with the dedicated wavelength channels of AWG. By measuring all of the reflection powers reflected at the OFTs with a proposed on-site reflectometer, the water level can be monitored continuously for a fast emergency response. Moreover, it can be implemented easily with the commercially available optical components and devices with the simple configuration.

• Spatial Information Research
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• 제23권1호
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• pp.19-31
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• 2015

최근 전 세계적인 기온상승과 불규칙한 이상기후로 인하여 지역간 수자원 격차 및 물부족 현상이 나타나고 있으며 미래 물 수급의 안정성 확보를 위한 수자원 관리가 점차 중요해지고 있다. 이를 해결하기 위해 수자원의 안정적인 확보와 관리가 가능한 방안으로 대두되고 있는 Smart Water Grid (SWG) 연구가 진행되고 있다. 따라서 본 연구에서는 웹 환경에서 통합 물정보 제공을 위한 GIS 기반의 SWG 시뮬레이터를 설계하고자 하였다. 시스템 개발을 위해 사용자 요구분석을 기반으로 SWG 현황 조회, 미래 예측 및 정수장 현황 조회기능을 설계하였으며 사용자의 이해를 높이기 위해 GIS 및 HTML5 기술을 이용한 정보표출 기술을 적용하였다. 또한 비상 상황이 발생했을 때 SWG를 이용한 문제 해결 과정을 확인할 수 있도록 시나리오 재현 기능을 설계하였다. 시스템 개발을 위한 설계도로 Use-case, Class, Sequence diagram을 작성하고 최종 개발 내용을 확인하기 위한 스토리보드를 작성하였다. 본 연구를 통해 설계된 SWG 시뮬레이터는 기후변화 대응을 위한 물관리를 지원하기 위한 정보의 획득을 도울 뿐 아니라 시나리오 재현을 통한 의사결정자의 결정을 도울 수 있을 것으로 판단된다. 주요 기능이 수자원 관리자 및 생산자 위주로 설계되었지만 향후 소비자를 위한 콘텐츠와 기능을 추가로 개발하여 단방향 정보 전달이 아닌 양방향 정보 교환이 가능하도록 해야 할 것이다.