• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.39-44
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• 2005

In HANARO, a multi-purpose research reactor of 30 MWth, the emergency water supply system consists essentially of an emergency water storage tank located in the level of about thirteen meter (13 m) above the reactor core, a three inch ('3\%') diameter water injection pipe line including injection valves from the tank to the reactor cooling inlet pipe and a test loop to do periodic system performance test. When the water level of the reactor pool comes down to the extremely low due to a loss of reactor pool water accident the emergency water stored in the tank should be fed to the core by the gravity force and at that time the design flow rate is eleven point four kilogram per second (11.4 kg/s). But it is impossible periodically to measure the injection flow rate under the emergency condition because the normal water level should be maintained during the reactor operation. This paper describes a flow network analysis to simulate the flow rate under the emergency condition. As results, it was confirmed through the analysis results that the calculated flow rate agrees with the design requirement under the emergency condition.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.78-81
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• 2009

연료펌프에 대한 수력성능시험을 상온의 물을 매질로 하여 실시하였다. 시험된 연료펌프는 개방형 가스발생기 방식의 75톤급 액체로켓엔진에 적용할 목적으로 개발 중에 있다. 시험 결과, 연료펌프는 설계요구조건을 만족하였으며, 설계 유량에서의 양정과 효율은 수치해석에서 추정된 값보다 높았다. 또한 후방 베어링의 출구 압력이 예상보다 높았는데 이는 바이패스 배관의 입구가 좁기 때문이었다. 그리고 바이패스 곡관부의 차압 측정으로 누설 유량을 유추할 수 있었다.

• 한국태양에너지학회 논문집
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• 제33권1호
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• pp.57-65
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• 2013

The temperatures with the ground depth, the positions of circulation water in ground heat exchanger were measured and thermal diffusion characteristics with the distances of the direction normal to the borehole was analysed. The deeper the depth of ground, the less the influences of outdoor temperature, but below 10m of ground, there was no influences of ground temperature. When the depth of trench pipe was below the depth of 2m, there was no influence. In the ground of 10m when the distances between the pipe and the other places were above 0.5m, the variations of temperature were less than $1.6^{\circ}C$ and above 2.5m they were less than $0.1^{\circ}C$. When the distances of bore hole were above 5m, there were no. influences of the nearest ground heat exchanger.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2100-2105
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• 2008

A numerical analysis was conducted to predict the heat transfer characteristics of a high-temperature, high heat flux solar receiver as the end-wall angle varied. The concentration ratio of the solar receiver ranges from 200 to 1000 and the concentrated heat is required to be transported to a certain distance for specific applications. This study deals with a solar receiver incorporating high-temperature sodium heat pipe as well as a typical one that employs a molten-salt circulation loop with the same outer dimensions. The isothermal characteristics in the receiver section is of major concern. The diameter of the solar thermal receiver was 120 mm and the length was 400 mm. FLUENT, a commercial software, was employed to deal with the radiative heat transfer inside the receiver cavity and the convection heat transfer along the channels and heat pipes. The numerical results were compared and analyzed from the view point of heat transfer characteristics the solar receiver system.

• 설비공학논문집
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• 제5권3호
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• pp.207-216
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• 1993

Experimental investigations have been carried out to find the effect of drag reduction caused by effective polymer additives in turbulent flows. The experiments were undertaken with a test section of 9.8mm pipe diameter and 3500 mm pipe length(L/D=357) in a closed loop, and Copolymer-X and Polyacrylamide(PAAM) were used as polymer additives for comparisons. The tests were carried out under different polymer concentrations, and the temperatures of the flow considered were $26^{\circ}C$, $60^{\circ}C$ at the flow velocity of 5.3 m/s. The rate of drag reduction obtained by Copolymer-X is found to be considerably higher than that of PAAM in turbulent flows. Copolymer-X is also found to be very reliable for mechanical degradation, which has not been the case in any other additives. It is concluded that Copolymer-X is considered to be one of the most effective agents as an additive especially for long time hydraulic transports. It is also found that polymer degradation in more likely at lower polymer concentrations in the turbulent flows.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.422-429
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• 2008

The objective of the present study is to develope a propultion unit cooling system for the next-generation High-speed EMU. The propulsion power control unit consists of some IGBT semiconductors. In general, those power semiconductors are very sensitive to temperatures and need a cooling system to keep them at a proper operational conditions in the range of $50{\sim}100^{\circ}C$. In this first year of study, we tried to focuss on the understanding of fundamental technologies for each of the two different cooling systems and collecting basic data for design and manufacturing for both cases. For the water cooling system, a heat sink with multi channels of liquid flow was considered and a model unit was designed and performance test was conducted. For the heat pipe cooling system, a Loop Heat Pipe(LHP) was considered as an element to transport heat from IGBT to environment air flow and a model unit was designed and performance test was conducted. The analysis using SINDA/FLUINT showed that those design parameters are good enough for the LHP to properly operate under a heat load up to around 360W.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.383-387
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• 2004

The Fuel Test Loop (FTL) consists of In-Pile Test Section (IPS) and Out-of-Pile System (OPS). The test condition in IPS such as pressure, temperature and quality of the main cooling water, can be controlled by the OPS. The FTL has been developed to be able to irradiate three pins to the core irradiation hole (IR1 hole) by considering for its utility and user's irradiation requirement. The IPS vessel assembly (IVA) consists of IPS head, outer pressure vessel, inner pressure vessel, inner assembly and test fuel carrier. The IVA is approximately 5.6 m long and fits within a 74 mm in diameter envelope over the full height of the chimney. Above the top of the chimney, the head of the IPS is enlarged to allow the closure flanges and pipe work connections. IVA was designed to test the CANDU and PWR nuclear fuel pin together. Specially, wished to minimize interference by nuclear fuel change in design and synthesize these items and shape design for IVA.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.216-221
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• 2005

The heat transfer coefficient and pressure drop during gas cooling process of carbon dioxide in a helically coiled tube were investigated experimentally. The experiments were conducted without oil in the refrigerant loop. The main components of the refrigerant loop are a receiver, a variable speed pump, a mass flowmeter, a pre-heater, a gas cooler(test section) and an isothermal tank. The test section is a double pipe type heat exchanger with refrigerant flowing in the inner tube and water flowing in the annulus. It was made of a copper tube with the inner diameter of 4.85 [mm], the outer diameter of 6.35 [mm] and length of 10000 [mm]. The refrigerant mass fluxes were 200${\sim}$600 [kg/$m^2$s] and the average pressure varied from 7.5 [MPa] to 10.0 [MPa]. The main results were summarized as follows: The heat transfer coefficient of supercritical $CO_2$ increases, as the cooling pressure of gas cooler decreases. And the heat transfer coefficient increases with the increase of the refrigerant mass flux. The pressure drop decreases in increase of the gas cooler pressure and increases with increase the refrigerant mass flux.

• Nuclear Engineering and Technology
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• 제24권3호
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• pp.311-318
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• 1992

원자력 발전소에서 Mid-loop 운전시 배관내에서 발생하는 자유수면 와동으로 인해 잔열 제거계통 배관내 공기가 흡입될 가능성이 있으며 이로 인한 계통상실 방지를 위하여 수위와 흡입유량과의 관계를 실험을 통해서 H/d, 프라우드수, 레이놀즈 수 등과 같은 무차원 수로 구하였다. 실험결과 레이놀즈수는 크게 영향을 미치지 않았으며 주로 프라우드수가 자유수면 와동을 지배하는 것으로 판명되었다. 한편 운전시 펌프나 밸브의 개폐로 인한 수면의 섭동이 와동에 많은 영향을 미치는 것이 밝혀졌다. 원자력 발전소의 안전과 관련하여 배관내에서 와동으로 인한 공기흡입 방지책으로 Reducer형의 흡입구 개선방안을 제시하였다.

• 한국지열·수열에너지학회논문집
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• 제14권4호
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• pp.35-42
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• 2018

Among the various ground source heat pump systems, vertical-type heat pump systems have been distributed greatly. Most of the vertical-type ground source heat pump systems have been designed based on the Korean Ministry of Knowledge Economy Announcement in Korea. In this study, the design process of the vertical-type ground source heat pump system in the announcement was analyzed, and the effects of the design parameters on the ground loop heat exchanger were investigated. Borehole thermal conductivity was the highest dominant design parameter for ground loop heat exchangers. The borehole thermal conductivity was changed according to the pipe and grout thermal conductivity. For optimal design of the ground heat pump system, it is highly recommended that the design process in the announcement will be revised to adopt the various tubes and grout which have higher thermal conductivity. In addition, the certification standard for heat pump unit should be revised to develop the heat pump with a small flow rate.