• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.397-400
• /
• 2008

To carry out this study efficiently, the material, physical and mechanical properties of the existing high temperature area was identified and the thermal transportation of structural elements was carried out through the finite element analysis method(ABAQUS) for 40 to 100 MPa high strength concrete based on Fiber Cocktail mixing. The results are as follows. First, it was analyzed that 40, 50 and 60 MPa high strength concretes have a thermal transportation properties similar to the analysis model of 30 MPa normal concrete. Second, it was analyzed that the analysis model of 80 and 100 MPa high strength concrete have slightly lower thermal transportation properties compared to normal model. Third, this study didn't consider the explosive spalling by the pore pressure within high strength concrete. If the properties for the pore pressure within high strength concrete is considered and database by strength and by inner temperature of various high strength concrete and steel materials are established in the future, it is interpreted that the technical foundation will be laid for performance-based design of fire-resistant construction.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.10 no.1
• /
• pp.96-101
• /
• 1986

The average heat transfer coefficient of 2-D impinging jet has been augmented as much as 60% on the wall with large-scale wavy roughness. The mechanism of this heat transfer augmentation is studied with emphasis on two primary flow structures in the impinging flow region by using either the surface floating method or the smoke-wire technique. They are the stream-wise vortex-like structure, which is characteristic to the impining jet, and the spanwise vortiecs associated with the flow separation around the roughness. The combined effect of these structures can effectively augment the heat transfer particularly in the downstream region where the teat transfer usually deteriorates consicerably.

• 한국기계연구소 소보
• /
• s.17
• /
• pp.5-11
• /
• 1987

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1997.12a
• /
• pp.243-248
• /
• 1997

• Journal of the KSME
• /
• v.34 no.11
• /
• pp.877-886
• /
• 1994

흡착계의 선택은 냉동기의 본질적인 성능을 결정하기 때문에 사용하는 열교환기의 전열특성, 시스템의 구성 등과 함께 중요한 위치를 차지하고 있다. 따라서 사용목적에 맞는 흡착계의 선 택이 중요하다. 여기서는 흡착식 히트펌프의 성능특성과 실용화를 위한 연구 개발 요점 등을 정리하였다.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1997.05b
• /
• pp.555-560
• /
• 1997

원자력발전소의 전열관 보수용접기술은 원전시설의 수명연장을 목적으로 개발된 기술이며, 손상된 Inconel 600 전열관 내부에 Inconel 690 재질의 sleeve tube을 삽입한 후 용접을 하는 방법으로 수행된다. 증기발생기 전열관 sleeve 레이저 용접의 기본개념은 방사능지역 외부의 발진기로부터 발진된 레이저빔을 광섬유를 이용하여 장거리(200미터 이상) 전송하여 전열관 내부의 광학계 및 회전장치를 이용하여 전열관을 용접하는 방법이다. 본 연구에서는 펄스형 레이저의 용접 변수인 펄스폭, 반복율, 첨두출력 및 용접속도를 변화시키면서 용입상태를 측정하였고, 용접된 시편에 열처리 여부와 부식실험을 위한 C-ring 시편을 제작하여 caustic test를 위해 auto-clave vessel에서 1,000 시간 실험을 실시하였다.

• Solar Energy
• /
• v.14 no.2
• /
• pp.51-60
• /
• 1994

The fluidization characteristics of the furan foundry sand fluidized bed and the heat transfer characteristics on a single spiral coil tube in the bed have been investigated. In the paper, the heat transfer coefficients for a single spiral coil tube are measured in the furan foundry sand bed as a function of the ratio of heated coil tube pitch to diameter(p/Do) and the ratio of heated coil tube pitch to particle size(p/dp). The experimental results are as follows. 1) Mean heat transfer coefficients increases according to the increasing ratio of heated coil tube pitch to diameter(p/Do). 2) The Increasing rates of mean Nusselt numbers are more greater in the case of p/Do=1.58 than p/Do=4.75. 3) Mean Nusselt number can be expressed by the following equation, $Nu_{mean}=C\;Re^m\;Pr_g^{0.4}(p/dp)^n$.

• Solar Energy
• /
• v.10 no.1
• /
• pp.38-46
• /
• 1990

For the optimal design and the efficient operation of the double pipe type latent heat storage equipment, the effect of the parameters of the system were analysed. The statistical analysis showed that the theoretical and the experimental results of the volume change rate and the temperature variations were well agreed. Therefore, this theoretical model is reasonable to analyze two dimensional moving boundary problems. In the analysis of the effects of the parameters, the heat extraction fraction and the water outlet temperature of the system as function of the time were analysed depending on the initial temperature of PCM, water inlet temperature, water mass flow rate and the dimension of the inner tube.

• Solar Energy
• /
• v.12 no.3
• /
• pp.116-125
• /
• 1992

By using the heat pipe with a dished evaporator and a screwed groove condenser, the heat transfer characteristics have been investigated by measuring temperature distributions of wall and vapor for various thermal inputs at rotative and stationary cases. The results show that the heat transfer characteristics of this pipe have better than those of simple heat pipe. The heat transfer of the heat pipe is increased by increasing thermal input and revolutions per minute.

• Solar Energy
• /
• v.14 no.2
• /
• pp.91-101
• /
• 1994

Heat release characteristics of a CaO packed bed reactor which is used for a chemical heat storage device has been studied. We employed Cu-plate fins to release the heat of reaction of the CaO packed bed inside the reactor fast and effectively. Two-dimensional analysis of unsteady state heat flow inside the bed was performed as a function of time and under various conditions of the Cu-plates. It is noted that the time required to release the heat of reaction with Cu fins is reduced more than twice fast compared to that without Cu fins. That was largely dependent upon the number of Cu-plate, as well.