• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.537-538
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• 2004

The performance of the ECWS was predicted for the anticipated operational occurrences. The inadvertent close of loop isolation valve is the most severe case for the five anticipated operational occurrences considered in this design and meets the design criteria of the ECWS. The correlation of critical heat flux for the geometry of three pins sub-channel analysis will be studied in the feature.

• Journal of Chest Surgery
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• v.23 no.5
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• pp.953-961
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• 1990

Congenitally corrected transposition of the great arteries is a rare congenital heart anomaly, in isolation, has no hemodynamic consequences. It is usually associated with one or more of a variety of intracardiac lesions, ventricular septal defect, valvular or subvalvular pulmonary stenosis, and deformity of the systemic atrioventricular valve with insufficiency. This report describes a successful two stage operation for congenitally corrected transposition, [SLL] type, with ventricular septal defect, pulmonary atresia, persistent ductus arteriosus, and atrial septal defect. A 9 years old patient underwent modified Blalock-Taussig operation because of severe pulmonary hypoplasia. 2 years later a corrective operation, direct closure of ASD and PDA, VSD closure with Dacron patch, Enlargement of left pulmonary artery with pericardial patch and Relief of ROTO with Rastelli procedure could be successfully performed without complication.

• Journal of Power System Engineering
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• v.7 no.3
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• pp.23-28
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• 2003

In heavy nuclear power plant, high energy through main steam line is provided to turbine that generate the electric power. Since plant had generated power, high noise has been occurred. Noise make equipments and work environment worse. For finding out the location and the cause of making noise, noise was measured along main steam line at open/close test of Main Steam Isolation Valve (MSIV hereafter). As the result, it was identified that the vortex shedding in the cavity of MSIV is main noise source. The profile change of MSIV seat ring was proposed as the method of noise reduction. After filletting MSIV seat ring, the noise level reduced $10{\sim}20dB$ compared before the change of profile.

• Journal of Korea Water Resources Association
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• v.39 no.2 s.163
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• pp.89-98
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• 2006

To evaluate the pipe failure impact, current methodologies consider only a broken pipe as the impacted area. However, these approaches are accurate if the broken pipe is the only area isolated from tile system. Depending on the number and locations of on-off valves, more pipes which are adjacent to a broken pipe may be isolated. Using the concept of Segment suggested by Walski, the methodology evaluating the pipe failure impact incorporated with on-off valve locations has been suggested by Jun. However, a segment cannot account for all possible pipe failure impacted areas since it does not consider additional failures, namely the network topological failure and the hydraulic pressure failure. For this reason, a methodology which can consider the network topology and hydraulic pressure limitation as well as on-off valve locations is suggested. The suggested methodology is applied to a real network to verify its applicability As results, it is found that a single pipe failure can affect huge areas depending on the configuration of on-off valves and the network topology. Thus, the applicability of the suggested methodology for evaluating the pipe failure impacts on a water distribution network is proved.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.63-72
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• 2010

MOV(Main Oxidizer shut-off Valves) control the combustion of launch vehicle systems by the supply and the isolation of liquid oxygen to a main combustion chamber in launch vehicle systems. Moreover, the MOV should secure a constant flow rate of liquid oxygen for combustion instability in the steady operational state. Although it has been showed that a EM(Engineering Model) with a high discharge coefficient value compared with the TM(Technology Model) fills the overall performance requirements, additional design modifications in some critical parts of the EM were conducted to improve the performance. The configurations of the pressure-control body, the middle flange, and the rips of the inlet body of the EM were modified and the performance tests have been performed with test models. Consequently, the intended improvements have been verified by the performance tests.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.771-775
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• 2008

Concerns related to protecting, identifying, and isolating of subsystems of a water distribution network have led to the realization of the increased importance of valves in the system. The most important purpose of valves in water distribution systems is to isolate subsystems due to breakage, maintenance activities, or contamination. A subsystem called segment is isolated by the closure of adjacent valves and an efficient algorithm should identify the adjacent valves to minimize the pipe failure impact. In this paper, an algorithm to identify adjacent valves to be closed to isolate a subsystem from the remainder of a network in case of a pipe failure is presented. An application to the water distribution system in Ottawa, Canada demonstrates the developed algorithm efficiently locates the adjacent valves for the isolation of a broken pipe.

• Journal of Korea Water Resources Association
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• v.38 no.7 s.156
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• pp.585-593
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• 2005

Recent concerns regarding protecting, identifying, isolating, redundant routing and dewatering of subsystems of water distribution networks have led to the realization of the importance of valves in these systems. Valves serve two purposes namely, flow and pressure control and isolating subsystems due to breakage or contaminant containment. In this paper, valves are considered from the point of view of subsystem isolation. When a water main is required to be closed, it may be in general necessary to close several other pipes in addition to the broken pipe itself depending on the distribution of adjacent valves. This set of pipes is defined as a segment. In this paper a segment analysis for isolating pipes is present and based on the segment analysis, we suggested the Valve Importance Index and the 7 performance indicators to evaluate the system performance. The suggested methodology is applied to a real network to verify the applicability of the methodology.

• Journal of computational fluids engineering
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• v.20 no.3
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• pp.87-93
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• 2015

In this study, a numerical analysis was performed to simulate the thermal-hydraulic response of the secondary side of a steam generator(SG) model equipped with an orifice-type SG outlet flow restrictor to a main steam line break(MSLB) at a pressurized water reactor(PWR) plant. The SG analysis model includes the SG upper steam space and the part of the main steam pipe between the SG outlet and the broken pipe end. By comparing the numerical calculation results for the present SG model to those obtained for a simple SG model having no flow restrictor, the effects of the flow restrictor on the thermal-hydraulic response of SG to the MSLB were investigated.

• Nuclear Engineering and Technology
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• v.15 no.4
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• pp.219-228
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• 1983

The blowdown history of the TMI-2 accident up to the isolation of the relief valve associated with a small break LOCA is reviewed briefly. An analysis is made to determine what instruments should be added in the core in order to prevent core damage in the case of the TMI-2 accident. With the added instruments a procedure is presented on how to predict the uncovered level of the core and how to calculate operator time margin. Sample calculations are done for the TMI-2 accident to determine the uncovered level and operator time margin. Finally, the map to show the uncovered level of the core and operator time margin is drawn with measurable parameters by the above methods.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.108-108
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• 2018

상수관의 노후화 혹은 공사 중 작업자의 실수, 또는 자연재해 등에 의해 상수관망 내 파손 관이 발생할 경우 파손된 관의 보수 및 교체 작업을 위해서는 파손 관과 인접한 밸브를 차폐하게 된다. 이로 인하여 관망의 일부 지역에 물 공급이 차단되는 단수구역이 발생하게 되며, 단수구역은 밸브를 닫음으로 인해 파손 관과 함께 격리되는 직접고립지역(segment)과 직접고립지역을 차폐함으로써 의도치 않게 수원으로부터 물 공급이 차단되는 간접고립지역(unintended isolation)으로 구분할 수 있다. 간접고립지역은 차폐된 직접고립지역으로 인해 수원으로부터의 유일한 용수공급 노선이 차단되어 발생한다. 관 파손에 의한 단수 피해를 현실적으로 모의하기 위해서는 밸브위치에 따른 단수구역을 정확히 산정할 필요가 있다. 단수구역은 파손관의 위치뿐만 아니라 차단 밸브의 개수 및 위치에 따라 달라진다. 따라서, 관 파손에 의한 단수피해를 최소화하기 위해서는 각 관로의 파손확률과 절점의 중요도를 고려하여, 적절한 밸브의 위치를 선정해야 한다. 본 연구에서는 관 파손에 따른 단수상황을 모의하여 파손 관에 의한 직, 간접 단수구역을 탐색한 후, 단수용량을 파악하고 이를 최소화하기 위한 밸브의 적정 위치를 최적화 알고리즘을 이용하여 결정하는 방안을 제시하였다.