• Journal of Advanced Marine Engineering and Technology
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• v.24 no.5
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• pp.52-57
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• 2000

Recently large capacity of electric equipment and increasing in atomic power generation are shown. One of the reason is shortage of the electric power supply for air conditioning load during summer. And every consumer is concerning about economical refrigeration and air conditioning system to decreases electric power consumption and decrease in global warming. For these necessities, ice making thermal storage system is required. Therefore, in this paper, the possibility of continuous slurry ice making using flowing organic water solution in cooled circular tube has been investigated. The experiments was carried out under some parameters of concentration and velocity of water solution, temperature of cooled tube wall, and control pressure in tube, As a result, four types of operating conditions in the pipe, that was supercooling, continuous ice making, intermittent ice making and ice blockage, were classified . And it was found that the critical condition for continuous ice making was acquired as a function of these experimental parameters.

• Journal of Korea Foundry Society
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• v.23 no.5
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• pp.286-290
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• 2003

본 연구에서는 Ni-Zr-Ti의 3원계 합금을 기본으로 하여, Si 및 Sn 등의 원소를 첨가하여 Ni-rich 영역에서 벌크 비정질 합금을 제조하였다. $Ni_{59}Zr_{20}Ti_{16}Si_2Sn_3$ 조성의 합금에서 injection casting에 의하여 약 58 K의 과냉각액상영역을 가지고 있는 직경 3 mm의 벌크 비정질 시편을 제조하였다. 이러한 우수한 비정질 형성능은 액상온도의 저하로 인해 낮은 온도까지 액상이 쉽게 과냉되기 때문인 것으로 사료된다. $Ni_{59}Zr_{20}Ti_{16}Si_5$ 합금은 두 단계에 걸쳐 결정화가 일어나는 반면, $Ni_{59}Zr_{20}Ti_{16}Si_2Sn_3$ 합금은 단일 단계에 의해 orthorhombic $Ni_{10}{(Zr,Ti)}_7$ 결정상과 cubic NiTi 결정상으로 결정화가 일어난다. 벌크 비정질 $Ni_{59}Zr_{20}Ti_{16}Si_2Sn_3$ 합금의 경우 압충강도는 2.7 GPa, 연신율은 약 2% 정도의 값을 가진다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.143-145
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• 2007

The correlation between crystallization and deformation behavior in the supercooled liquid region (SLR) of a $Cu_{54}Ni_{6}Zr_{22}Ti_{18}$ bulk metallic glass (BMG) alloy is investigated by compression tests, differential scanning calorimetry (DSC), electron energy loss spectrometry (EELS) and high resolution transmission electron microscopy (HRTEM). In the SLR, This BMG alloy was strongly depended on the deformation temperature and the alloy exhibits important change in deformation behavior after a given time which is directly connected to the development of crystallization. Compressive stress impeded decomposition and consequently retarded forming of nano-crystal, which led to enlarge the homogeneous deformation region of the BMG alloy in SLR during compression test.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.2
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• pp.168-174
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• 2002

In order to obtain a new heat transfer fluid having a high thermal capacity, micro-capsules of a phase-change material can be a successful candidate to be added into water. In this study, 25, 50, 100, and $200\mu$m diameter micro-encapsulated Lauric acids were tested by a differential scanning calorimeter. The Lauric acid itself had a single freezing curve, but the micro-encapsulated Lauric acid had double freezing curves. The second freezing dominated for $25\mu$m diameter Lauric acids. But the first freeing energy became big as the size of the capsule increased.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.1
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• pp.89-97
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• 1995

Experimental study was performed for free convection and ice formation around two horizontal circular tubes which were placed vertically. Temperature and velocity distributions were visualized with real time holographic interferometry technique and tracer method. When water was cooled, super cooled region was formed around cooling pipe. It was found that flow induced by free convection always directed downwards when the coolant temperature was low, while it directed upwards when the coolant temperature was comparably high though it directed downwards initially. Flow phenomena with free convection were investigated in detail with varying cooling rate and length between cooling pipes. And growing process of dense ice was also investigated. Dendritic ice is suddenly formed within a supercooled region, and a dense ice layer begins to develop from the cooling wall.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.6
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• pp.580-586
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• 2008

Icing cloud generation system was developed to perform the in-flight icing simulation test for T-50 Supersonic Jet Trainer on the ground. The developed system successfully generated the almost natural icing cloud in the super-cooled state (liquid state) below freezing point and with the required LWC (Liquid Water Content). For full-scale aircraft icing test, an icing scaling method was adopted due to the limitation of wind generation speed with open-circuit type blower and its applicability was experimentally verified. Under the required in-flight icing condition based on the icing scaling method, T-50 aircraft subsystems were successfully operated and functionally checked.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.332-334
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• 2003

A subcooled liquid nitrogen cryostat is required for the cooling of a 6.6 ㎸, 200 A resistive type superconductive fault current limiter (SFCL). To help understand and design an appropriate cryostat for SFCL a prototype cryostat was fabricated and tested. Several states of subcooled liquid nitrogen were obtained by using cryocooler and helium gas. The temperature was uniformly distributed inside the liquid nitrogen vessel within the range of 0.4 K proving the effectiveness of the conduction cylinder.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.122-125
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• 2006

This paper deals with the Ondol, Korean under-floor heating system using latent heat storage materials. It has been recognized that the heating system using the latent heat storage materials are economically efficient and comfortable. For the comparison and analysis to the data of the existing experiment, a repetitive experiment makes sure the ability of Ondol panel.

• Progress in Superconductivity and Cryogenics
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• v.9 no.3
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• pp.72-82
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• 2007

This paper relates to reducing the temperature of a cryogenic liquid by contacting it with gas bubbles, which can be characterized by diffusion-driven evaporative cooling, The characteristic of diffusion-driven evaporative cooling is thoroughly examined by theoretical. analytical and experimental methods specifically for the case of helium injection into liquid oxygen. The results reveal that if the gaseous oxygen partial pressure in helium bubbles is lower than the liquid oxygen vapor pressure, cooling occurs autonomously due to diffusion mass transfer. The method of lowering the injected helium temperature turns out to be very effective for cooling purpose.

• Journal of the Korean Society of Visualization
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• v.21 no.1
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• pp.47-56
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• 2023

Bubble condensation, which involves the interaction of bubbles within the subcooled liquid flow, plays an important role in the effective control of thermal devices. In this study, numerical simulations are performed using a VOF (Volume of Fluid) model to investigate the effect of tube diameter on bubble condensation. As the tube diameter decreases, condensation bubbles persist for a long time and disappear at a higher position. It is observed that for small tube diameters, the heat transfer coefficients of condensation bubbles, which is a quantitative parameter of condensation rate, are smaller than those for large tube diameters. When the tube diameter is small, the subcooled liquid around the condensing bubble is locally participated in the condensation of the bubble to fill the reduced volume of the bubble due to the generation of a backflow in the narrow space between the bubble and the wall, so that the heat transfer coefficient decreases.