• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.570-571
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• 2008

This paper presents a method for the determination of total transfer capability in interconnected power systems, which is based on sequential quadratic programming (SQP). The objective function is the maximization of the interconnected line flow. To calculate TTC the control variables are the active power of the generating units, the voltage magnitude of the generator, transformer tap settings and SVC setting. The state variables are the bus voltage magnitude, the reactive power of the generating unit, line flows and the tie line flow. The method proposed is applied to the modified IEEE 14 buses model system.

• 한국전산유체공학회지
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• 제21권3호
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• pp.89-97
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• 2016

In this study, direct code coupling, in which two codes share a single flow field, was conducted using 3-dimensional high resolution thermal hydraulics code, CUPID and 1-dimensional system analysis code, MARS. This approach provide the merit to use versatile capability of MARS for nuclear power plants and 3-dimensional T/H analysis capability of CUPID. Numerical Method to directly couple CUPID and MARS was described in this paper. The straight flow and manometer flow oscillation were calculated to verify conservation of coupled CUPID/MARS code in mass, momentum, and energy. This verification calculations indicates that the CUPID/MARS is coupled appropriately in numerical aspect and the coupled code can be applied to nuclear reactor thermal hydraulics after validation against integral transient experiments.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(2)
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• pp.574-579
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• 1995

Saturated boiling heat transfer experiment in a hemispherical narrow space is conducted using Freon-113 to investigate an additional heat removal capability through a hypothetical gap between lower head and degraded core. The narrow space of 1mm consists of a 124mm diameter heated stainless steel hemisphere and a glass outer vessel. Within the hemispherical narrow space large coalesced bubbles are produced and these bubbles rise in random direction, causing liquid flow in from the opposite side to fill the region. Such flow in random direction makes the flow field in the narrow space very chaotic and thus enhance heat transfer. The heat transfer coefficient is higher at lower angle and at higher heat flux. The present study shows that the liquid from upper region can effectively penetrate into the gap and augment the heat removal capability through tile gap.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.569-571
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• 2003

As a definition of NERC, Available Transfer Capability(ATC) is a measure of the transfer capability remaining in the physical transmission network for the future commercial activity. To calculate ATC, accurate and defensible TTC, CBM and TRM should be calculated in advance. In this paper, we propose a method to quantify TRM using probabilistic load flow based on the method of moment. Generation output, bus voltages, loads, and line outages are considered as complex random variables (CRV) to take into account for uncertainties related to the transmission network conditions. Probability Density Function (PDF) of line flow at the most limiting line is used to quantify TRM with the desired probabilistic margin. Suggested method is compared with the results from conventional CPF method and verified using 24 bus MRTS, and the suggested method based on PLF shows efficiency and flexibility for the quantification of TRM compared with the conventional method.

• KIEE International Transactions on Power Engineering
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• 제4A권4호
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• pp.192-200
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• 2004

This paper evaluates FACTS control on the available transfer capability (ATC) enhancement. Technical merits of FACTS technology on boosting ATC are analyzed. More effective control means for line flow and bus voltage require the application of FACTS. In this paper, the power flow calculation method for the power systems with FACTS is based on the current injection model (CIM) and the Newton-Raphson method. An integrated scheme for ATC calculation, which considers the dynamic characteristic of the power system, is suggested. The study is applied to the IEEE 57-bus power system to demonstrate the effectiveness of FACTS control on ATC enhancement.

• 대한전기학회논문지:전력기술부문A
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• 제53권8호
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• pp.446-453
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• 2004

This paper focuses on the evaluation of FACTS control on available transfer capability(ATC) enhancement. Technical merit of FACTS technology on ATC boosting are analyzed. More effective control means for line flow and bus voltage are required for appling FACTS. In this paper, the power flow calculation method for deriving FACTS control parameters based on current injection model(CIM) and newton method. Integrated scheme for ATC calculation considering dynamic characteristic of power system is suggested. Study is based on the IEEE 57-bus system demonstrate the effectiveness of FACTS control on ATC enhancement.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.496-500
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• 1996

An air flow measurement device is proposed. The thermal characteristic of a semiconductor element is adopted as a cooling parameter of thermal convection rate. The difference between forced convection and natural convection of two Zener diodes results enough difference in temperature. Experiment at various air flow conditions shows the measuring capability of the air flow in a duct. This measuring device has some merits, such as a reliability n hard field condition, simple circuit for signal processing, small volume of the element, less air flow resistance, independance of various ai temperature. The experimental result shows that it is an exact and usefull air flow measurement device.

• 대한전기학회논문지:전력기술부문A
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• 제55권6호
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• pp.236-241
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• 2006

This paper presents a transfer capability enhancement process using VSC HVDC system which can control active power as well as reactive power. The transfer capability is constrained by stability like voltage stability as well as thermal rating of power system components. Transfer capability of the power system limited by these constraints may be enhanced by reactive power control ability and active power flow control ability of the VSC HVDC system. To enhance the transfer capability of the system using VSC HVDC, selection of the HVDC installation site is performed. In this work, power zones which consist of major power plants and their sinks are identified using power tracing and distribution factor. Alternative route of major AC transmission line in the power zone is identified as VSC HVDC system.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(1)
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• pp.641-646
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• 1998

In order to enhance the dynamic and interactive simulation capability of a system thermal hydraulic code for nuclear power plant, applicability of flow network models in SINDA/FLUIN $T^{™}$ has been tested by modeling feedwater system and coupling to DSNP which is one of a system thermal hydraulic simulation code for a pressurized heavy water reactor. The feedwater system is selected since it is one of the most important balance of plant systems with a potential to greatly affect the behavior of nuclear steam supply system. The flow network model of this feedwater system consists of condenser, condensate pumps, low and high pressure heaters, deaerator, feedwater pumps, and control valves. This complicated flow network is modeled and coupled to DSNP and it is tested for several normal and abnormal transient conditions such turbine load maneuvering, turbine trip, and loss of class IV power. The results show reasonable behavior of the coupled code and also gives a good dynamic and interactive simulation capabilities for the several mild transient conditions. It has been found that coupling system thermal hydraulic code with a flow network code is a proper way of upgrading simulation capability of DSNP to mature nuclear plant analyzer (NPA).

• 터널과지하공간
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• 제8권4호
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• pp.332-341
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• 1998

석판재의 모서리 가공작업은 많은 경우 자동화가 이루어지고 있지만 제품의 형태 가 복잡해지면 여전히 수작업에 의해 연마가 이루어지고 있다. 본 논문을 성형공구의 제작 에 앞서 성형공구의 특성과 장비의 운영요소들의 변화에 따른 연마절삭성능을 파악하기 위 한 기본시험이 수행결과를 나타내는 것이다. 장비의 운영요소는 헤드의 회전속도 및 이송속 도, 가압하중, 급수율, 절삭방향과 이송방향이 포함된다. 실험결과는 연마절삭성능 즉 공구 마모 무게에 대한 판재의 절삭량으로 표시하였고, 각 운영요소들 마다의 적정 운영수준이 제시되어 있다. 또한 연마재 투입략의 변화에 대한 마모시험에서는 마모도는 연마재의 증가 에 따라 증가하지만 어느 이상의 양에서는 오히려 감소하고 있다.