• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.103.2-103
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• 2001

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1017-1018
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• 2011

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1997.11a
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• pp.229-234
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• 1997

밀폐공간내에서 일어나는 자연대류 열전달은 태양열 집열판, 연료탱크, 원자로의 핵반응로, 초전도 자성체의 냉각 및 건물이나 방의 효율적인 열설계, 화재시의 안전대책등 공업적으로 그 응용성이 매우 광범위하고 다양하게 생활주변에서 흔히 볼 수 있다. 밀폐공간내에 경계층 유동이 존재할 경우, 이 경계층 흐름은 일반적으로 외부유동에서의 경계층 유동과는 달리 코어영역(Core region)에서의 흐름과 서로 밀접한 관계가 있다. (중략)

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.9
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• pp.694-702
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• 2003

A cooling mechanism using acoustic streaming by ultrasonic vibrations and associated convective heat transfer enhancement is investigated experimentally and analytically. Acoustic streaming pattern and associated heat transfer characteristics are presented. Analytical transient temperature profile of the heated plate following Nyborgs theory is accomplished along with experimental measurement. A temperature drop of 30 C is obtained in 4 minutes with vibration amplitude of 10${\mu}{\textrm}{m}$. As the vibration amplitude is further increased to 25${\mu}{\textrm}{m}$ a temperature drop of 40 C is achieved that is the maximum temperature drop obtained with the current experimental apparatus. Analytical heat transfer solutions verified a temperature drop of 4$0^{\circ}C$ with a vibration amplitude of 25${\mu}{\textrm}{m}$ at 28.4 kHz which is experimentally obtained.

• Nuclear Engineering and Technology
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• v.27 no.3
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• pp.281-291
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• 1995

The objective of this work is to obtain the experimental data for the heat transfer processes occurring both on the inside and outside surfaces of containment steel wall with dry and wet outer surface conditions in the passive containment cooling system. The test model represented a 60$^{\circ}$ section of a containment vessel based on the AP 600 geometry. Major linear dimensions of the test model ore reduced tv a factor of ten. To simulate the decay heat a steam generator heated by electricity was placed in the test model. The maximum heat flux was 8.91 kW/$m^2$. Two types of tests were performed. The one was the tort on the natural convection of air without water film flow. The other was the evaporative heat transfer test with the falling water film flow and natural air draft. no test result shooed that the heat transfer capability by the natural convection from the containment to the air without oater film flow was limited at about 1.48 kW/$m^2$ heat flux. It was found that the heat removal capability was remarkably enhanced in the tests with the waster film flow and air draft. The obtained heat transfer data ore compared with the existing correlations.

• The Magazine for Energy Service Companies
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• s.62
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• pp.58-65
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• 2010

최근 가정용 컴퓨터와 노트북 등의 중앙처리장치(CPU) 속도가 급격히 빨라지고 있다. 더욱이 화석 에너지 고갈 위기에 따라 제품의 발열량은 급속도로 늘어날 전망이라는 관측이 나왔다. 때문에 에너지절약에 대한 해결이 동반된 연구가 이뤄져야 한다는 목소리가 커지고 있다. 이러한 문제를 해결하기 위해 발열원에 히트싱크를 직접 부착하는 강제대류 방식에 대한 연구가 진행되고 있고, 최근 들어 열전소자를 이용한 냉각방식과 히트파이프를 이용한 방식도 대두되고 있다. 그 중 열저항 특성 연구에 집중했던 기존 방식에서 벗어나 Pulsating Heat Pipe(PHP)를 열확산기로 적용시킨 연구방식을 소개한다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.11a
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• pp.111-116
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• 2002

고온의 소듐을 냉각재로 사용하는 풀형 액체금속로인KALIMER[1]는 기존의 경수로에 비해 고온에서 운전되므로, 잔열제거계통은 공기 자연순환에 의해 격납용기(CV) 외벽을 직접 냉각하는 방식의 PSDRS(Passive Safety-grade Decay Heat Removal System)[1]를 사용하며, 특히 고온의 구조물 표면온도에 의해 대류전열 외에도 복사전열과정이 활발히 일어난다.(중략)

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.95-103
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• 1998

오늘날 전기 철도 차량의 속도제어방식에는 A.C모터의 속도를 제어하는 방식을 많이 사용하고 있고 이 경우 여러 개의 GTO thyristor와 다이오드가 필요하다. 그런데 이러한 반도체 소자들은 전기 부하의 일부를 저항열로 소모하며 반도체의 용량에 따라 차이가 있으나 전기 철도 차량의 경우 약 1~2㎾의 열이 발생한다. 따라서 이들 소자들이 적정온도범위(100~12$0^{\circ}C$미만)를 유지하기 위해서는 소자의 내부저항열을 외부로 방출시켜야 한다. 지난 30여 년 동안 이러한 반도체 소자 냉각에는 강제대류, 침적 비등, 히트파이프식 냉각방법이 적용되어 왔다. 최근에는 히트파이프식 냉각방법이 유지보수, 크기 및 중량 등 여러 측면에서 상대적으로 유리하기 때문에 히트파이프식 냉각방법을 주로 사용하고 있다. (중략)

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.1
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• pp.53-62
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• 2017

The forced convection heat transfer performance of a twist-vane spacer grid for a dual-cooled annular fuel assembly was examined experimentally. The twist-vane spacer grid was uniquely designed to enhance mixing inside subchannels and mixing between adjacent subchannels. For testing, a $4{\times}4$ square-arrayed rod bundle with narrow gaps between rods was prepared as the dual-cooled annular fuel assembly to be simulated. The pitch-to-rod diameter ratio of simulated dual-cooled annular fuel assembly was 1.08. The experiments were performed under the following conditions: axial bulk velocity, 1.5 m/s and heat flux, $26kW/m^2$. With regard to the circumferential temperature distribution, the lowest rod-wall temperatures upstream and downstream were measured at the subchannel center and the position toward the tip of twist-vane, respectively. With regard to the axial temperature distribution, behind the twist-vane spacer grid, the rod-wall temperature decreased drastically, and the Nusselt number was enhanced by up to 56 %. The present measured data indicate that the twist-vane spacer grid can effectively improve the forced convection heat transfer in the dual-cooled annular fuel assembly with narrow gaps.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.6
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• pp.844-853
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• 1998

Natural and forced convection experiments were carried out in order to investigate the effects of channel spacing gap between protrusions and number of rows of protrusion, In natural convection the optimum channel spacing was found to be approximately 20mm regardless of the protrusion gaps. For optimum channel spacing the heat transfer coefficients were converged to an asymptotic value after the fourth row. The heat transfer coefficient for each row approaches to constant values for protrusion gaps larger than 10 mm. An experimental correlation has been suggested by using a modified Rayleigh number based on the dimensionless characteristic length(G/L). In forced convec-tion the heat transfer coefficients were not merged to an asymptote until the fifty row and increases as the channel spacing at the constant Reynolds number decreases.