• 건축구조
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• v.13 no.3
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• pp.90-91
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• 2006

21세기를 맞이하여 한국 건설산업은 새로운 시장환경에 직면할 것으로 예상됨에 따라 이에 부응하는 산업발전과 대국민 역할 증대 방안을 모색하지 않으면 안될 것이다. 무엇보다 전통적인 신축중심의 건설 수요는 장기적으로 성장세가 둔화될 것으로 전망되어 기존 건축물을 대상으로 하는 리모델링에 대한 수요는 이러한 건설수요의 구조변화에 동반하여 나타나는 현상으로 21세기 건설시장을 주도해 나갈 것으로 예상된다. 이러한 발전 가능성을 갖고 있는 2000년대 리모델링 시장의 성장 가능성을 전망하고, 활성화를 위한 구조 방안을 모색하고자 한다.

• Journal of the Korean Chemical Society
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• v.35 no.3
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• pp.288-291
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• 1991

• Journal of the Korean institute of surface engineering
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• v.36 no.6
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• pp.437-443
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• 2003

The effects of additive(grain refiner, GR) on process efficiency of the Ni-Fe-P alloy electrodeposition and the material properties of the deposit were investigated. Electrochemical properties of the deposits were investigated using polarization and electrochemical impedance techniques, and the material properties of the deposits were characterized through inductively coupled plasma(ICP), spiral contractometer, XRD, SEM and TEM. When the additive was added into the electrodeposition bath, current efficiency, Ni content and corrosion resistance of the deposit increased, whereas residual stress, surface roughness and grain size of the deposit decreased.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.720-722
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• 2002

Superconducting synchronous motor using HTS(high-temperature superconducting) field windings has a lot of advantages over LTS(Jow-temperature superconducting) synchronous machine. A recently developed 5000[hp] HTS motor represents 1/2 reduction in weight and volume compared to an induction type conventional machine. Furthermore. 40% machine loss is reduced compared to the industry average. Based on a conceptual design, a 100[hp] HTS synchronous motor is modeled by F.E.M(Finite Element Method) and the performance is predicted in this paper

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.741-743
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• 2002

Some different types of joining between two parallel high Tc superconducting tapes were prepared and I-V characteristic curves were obtained at the atmosphere of liquid nitrogen. Resistances in joint parts were estimated from I-V curves. We selected the best jointing method among these methods and its resistance were obtained at 28K. The availability of this joint method for fabricating HTS field coils is discussed.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.732-734
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• 2002

The rotor thermal analysis consists of determining the heat load to the rotor, sizing the cryogenic system, and ensuring that the HTS rotor will operate at the design goal of 30 K. The heat load to the rotor is due to heat conduction through the torque tubes, current leads, instrumentation. and radiation from the thermal shield and the end caps. Coil operating temperature is determined from the coil losses and the heat transport to the coolant. An FEM thermal conductivity model is developed to allow calculation of heat transport in HTS field coil according to the heat exchanger shape and coolant feeding method. The losses determine the size of the cryocooler.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.215-218
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• 2002

HTS motors and generators have some advantages over LTS machines because of higher operating temperature. Very low temperature nakes LTS machines need higher refrigeration cost and large facilities. However, HTS machines are expected to be comparable with conventional counterparts at smaller machine ratings than LTS generators in terms of efficiency and size. As the operating temperature increases, the magnetic flux density generated by HTS field coils decreases relatively. For example, 1000hp HTS synchronous motor developed in a few years ago has maximum field density of 1.5T. At this point, magnetic material used in conventional machines is able to pass magnetic flux easily with high permeability. In order to investigate the effect, we arranged magnetic core only inside of magnet vessel of a 100hp target machine. By way of FEM analysis, we concluded that the magnetic core can reduce amount of expensive BSCCO conductor so much.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.315-317
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• 2002

The value of I$_{c}$(critical current) in HTS (High Temperature Superconducting) tape has a great influence on B(equation omitted) (magnetic field amplitude applied perpendicular to the tape surface). Therefore, I$_{c}$ of HTS magnet is determined by not only operating temperature but also the B(equation omitted). In shape design of field coil for the HTS motor, a method to reduce the B(equation omitted) and to determine operating current should be considered in order to optimal design. On the basis of the magnetic field analysis, this paper deals with various field coil shape to obtain operating current of HTS motor by using analytical method. And also this paper discusses the operating current of 100hp class HTS motor by using I$_{c}$-B(equation omitted) curve.curve.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.3
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• pp.581-587
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• 2001

Plate heat exchange(PHE) will be applied to the refrigeration and air conditioning systems as evaporators or condensers for their high efficiency and compactness. The purpose of this study is the analyze the characteristics of heat transfer and pressure drop of plate heat exchanger. Numerical work was conducted using the FLUENT code k-$\varepsilon$model. Also the dependence of heat transfer coefficient and friction factor on Reynolds number was investigated. As the Reynolds number increases, it is found that heat transfer coefficient also increases, but friction factor decreases. The study examines the internal flow, thermal distribution and the pressure distribution in the channel of plate heat exchanger. The results of CFD analysis compared with experimental data, and the difference of friction factor and Nusselt number in plate heat exchanger are 10% and 20%, respectively, Therefore the CFD analysis model is effective for the performance prediction of plate heat exchanger.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.4
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• pp.422-429
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• 2000

Plate and shell heat exchanger(P&SHE) is widely applied as evaporators or condensers in the refrigeration and air conditioning systems for their high efficiency and compactness. In order to set up the database for the design of the P&SHE, heat transfer and pressure drop characteristics for single phase flow of water in a plate & shell heat exchanger are experimentally investigated in this study. Single phase heat transfer coefficients were measured for turbulent water flow in a plate and shell heat exchangers by Wilson plot method. The shell side heat transfer resistance was varied and the overall heat transfer coefficients were measured. The single-phase heat transfer coefficients in a plate side were obtained by Wilson plot method. Single-phase heat transfer correlations based on projected heat transfer area and friction factor correlations have been proposed for single phase flow in a plate and shell heat exchanger.