• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.375-375
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• 2006

The preparation methods are to be used as "melting method" and "absorption method", respectively. The reaction mixture in the reaction container was heating up the reaction mixture to $200^{\circ}C$ for 2 hour. The mixing time of lab scale preparation should be provided quit long, instead of the short working time in a compounder vessel. And The PP-PCM mixture in the reaction container was heating up the mixture around $60-80^{\circ}C$ for 2 hour. A melting method of frozen gel with 50/50 weight ratio of polypropylene-normal octadecane was prepared by adding PP chip and normal octadecane. An absorption method of frozen gel with 70/30 weight ratio of PP 4.8-normal n-octadecane was prepared by adding PP powder and normal octadecnae.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2001.04b
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• pp.31-33
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• 2001

잠열축열 그린하우스 난방 시스템의 난방특성을 분석하기 위하여 이에 대한 열평형 이론을 정립하고 수치해석에 의하여 컴퓨터 시뮬레이션 모델을 개발하고자 잠열축열 그린하우스 난방 시스템의 열저항 회로망을 구성하였다. 그리고 그린하우스의 피복재, 내부 공기, 토양표면, 잠열 축열재와의 열평형 방정식을 구성하였으며, Newton-Raphson반복법을 이용하여 수치해석을 하였고, 실험 분석을 통하여 수치해의 타당성을 검증하였다. 시뮬레이션 모델을 위하여 C언어를 사용하였으며, 겨울철 (11월-2월)의 기후 조건이 유사한 여러 날을 선정하여 온도, 태양강도, 상대습도, 토양 수분함량 등을 자료로 하여 모델링을 하였다. 여기에 사용된 토양 조건은 사양토로 건조한 상태를 유지하였다. 이상과 같은 분석에 의하여 그린하우스내 경시적 공기온도 변화와 열전달 현상의 실험치와 이론분석 결과가 잘 일치하고 있음을 알 수 있었다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.1 no.4
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• pp.319-329
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• 1989

Heat transfer phenomena during inward melting and solidification process of the phase change material were studied expertimentally. The phase change medium was 99% pure n-docosane paraffin ($C_{22}H_{46}$). The solid-liquid interface motion during phase change was recorded photographically. Measurements were made on the temperature, the solid-liquid interface, the melted or frozen mass and the various energy components stored or extracted from the cylinder wall. For melting, the experimental results reaffirmed the dominant role played by the conduction at an early stage, by the natural convection at longer time. For solidification, natural convection effects in the superheated liquid were modest and were confined to short freezing time. Although the latent energy is the largest contributor to the total stored or extracted energy, the aggregate sensible energies can make a significant contribution, especially at large cylinder wall superheating or subcooling, large initial phase change material subcooling or superheating.

• Journal of Hydrogen and New Energy
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• v.30 no.3
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• pp.282-288
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• 2019

When liquefied natural gas (LNG) is vaporized to form natural gas for industrial and household consumption, a tremendous amount of cold energy is transferred from LNG to seawater as a part of the phase-change process. This heat exchange loop is not only a waste of cold energy, but causes thermal pollution to coastal fishery areas by dumping the cold energy into the sea. This project describes an innovative new design for reclaiming cold energy for use by cold storage warehouses (operating in the 35 to $62^{\circ}C$ range). Conventionally, warehouse cooling is done by mechanical refrigeration systems that consume large amounts of electricity for the maintenance of low temperatures. Here, a closed loop LNG heat exchange system was designed (by simulator) to replace mechanical or vapor-compression refrigeration systems. The software PRO II with PROVISION V9.4 was used to simulate LNG cold energy, gas re-liquefaction, and the vaporized process under various conditions. The effects on sensible and latent heats from changes to the array type of heat exchangers have been investigated, as well as an examination of the optimum.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.578-584
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• 2013

Ice slurry that is a mixture of fine ice crystals and liquid water is a widely used working fluid in the ice thermal energy storage system due to its flowability and large latent heat of fusion. Generally ice slurry is made from supercooled water. But the excessive supercooling causes the water to freeze even worse to block the pipe. Additionally large degree of supercooling of water degrades the efficiency of the ice thermal energy storage system. Therefore the effective method to control the phase change from supercooled water to ice slurry is needed. In this paper we experimentally studied a novel method to generate the ice slurry from the supercooled water using the ultrasonic vibration. It was found that the cavitation impact of supercooled water by ultrasonic vibration can help the generation of ice slurry.

• 한국해양학회지
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• v.30 no.2
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• pp.91-115
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• 1995

Air-sea heat fluxes in the East Sea were estimated from the various ship's data observed from 1961 to 1990 and the JMA buoy #6 data from 1976 to 1985. The oceanic heat transport in the sea was also determined from the fluxes above and the heat storage rate of the upper layer of 200m from the sea surface. In winter, The incoming solar radiation is almost balanced with the outgoing longwave radiation. but the sea loses her heat through the sea surface mainly due to the latent and sensible heat fluxes. The spatial variation of the net surface heat flux is about 100 Wm/SUP -2/, and the maximum loss of heat is occurred near the Tsugaru Strait. There are also lots of heat losses in the southern part of the East Sea, Korea Strait and Ulleung Basin. Particularly, the heat strong loss in the south-western part of the sea might be concerned with the formation of her Intermediate Homogeneous Water. In summer, the sea is heated up to about 120∼140 Wm/SUP -2/ sue to strong incoming solar radiation and weak turbulent heat fluxes and her spatial variation is only about 20 Wm/SUP -2/. The oceanic heat flux is positive in the southeasten part f the sea and the magnitude of the flux is larger than that of the net surface heat flux. This shows the importance of the area. In the southwestern part of the sea, however, the oceanic heat flux is negative. This fact implies cold water inflow, the North Korean Cold Water. The sigh of net surface heat flux is changed from negative to positive in March and from positive to negative in September. The heat content in the upper surface 200 m from the sea surface reaches its minimum in March and maximum in October. The annual variation of the net surface heat flux is 580 Wm/SUP -2/ in southwestern part of the sea. The annual mean values of net surface heat fluxes are negative, which mean the net heat transfer from the sea to the atmosphere. The magnitude of the flux is about 130 Wm/SUP -2/ near the Tsugaru Strait. The net surface fluxes in the Korea Strait and the Ulleung Basin are relatively larger than those of the rest areas. The spatial mean values of surface heat fluxes from 35$^{\circ}C$ to 39$^{\circ}$N are 129, -90, -58, and -32 Wm/SUP -2/ for the incoming solar radiation, latent hear flux, outgoing longwave radiation, and sensible heat flux, respectively.

• Journal of the Korean earth science society
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• v.34 no.6
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• pp.561-574
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• 2013

This study investigates energy fluxes measured near Gangjeong-Goryeong Weir of the Nakdong River of South Korea for more than a year, from July 2011 to September 2012, in order to analyze the applicability of the data for future impact analyses. Each of the two study sites is located in a rural area, surrounded by agricultural fields, and an urban industrial area. Sensible and latent heat fluxes are analyzed according to the wind direction. In the summertime, when the wind blows from the river, sensible heat tends to decrease and latent heat tends to increase at both sites. This result is considered to be caused by moisture transfer from the river. Bowen ratio, energy balance closure, momentum flux, and stability are analyzed as well. The Bowen ratio of the rural agricultural site turns out higher than that of the urban site regardless of the season. The energy balance closure is higher at the agricultural site compared to the urban area, which is mainly due to exclusion of the storage term calculation at the urban site. The momentum flux is greater at the urban site both in winter and summer. The instability lasts longer during daytime and in the summertime, when there is a strong turbulence. The data from these sites are appropriate to be used in analyzing the impact of river in surrounding areas for future studies.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.1
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• pp.60-68
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• 2012

In this study, the manufacturing process of micro capsulized PCM (phase changing material) for thermal storage performance of latent heat was investigated to save energy during the use of buildings: i.e. use of melamine-type resin as the micro-capsule material and paraffin wax as the inner material that are together used in concrete walls. For the manufacturing process of the micro-capsulized PCM, the amount of SDS addition as surfactant was the key variable and the resulting thermal storage performance depended on the SDS amount. With increasing amount of SDS, the micro capsulation became much easier while the capsule surface became harder. The micro capsules became uniform at an optimum SDS addition. The addition of SDS also affected the thermal capacity: with increasing SDS amount, the heat storage and release tendency at melting point was more clearly manifested. The current investigation is part of a study under progress to explore the use of PCM in concrete walls to save building maintenance cost and energy.

• Journal of Biosystems Engineering
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• v.40 no.3
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• pp.271-276
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• 2015

Purpose: Quick freezing is widely used in commercial food storage. Well-known freezing techniques such as individual quick freezing require a low-temperature coolant and small cuts for the heat-transfer efficiency. However, the freezing method for bulk food resembles techniques used in the 1970s. In this study, electromagnetic (EM) heating was applied to improve the quick freezing of bulk food. Methods: During freezing, the surface of food can be rapidly cooled by an outside coolant, but the inner parts of the food cool slowly owing to the latent heat from the phase change. EM waves can directly heat the inner parts of food to prevent it from freezing until the outer parts finish their phase change and are cooled rapidly. The center temperature of garlic cloves was probed with optical thermo sensors while liquid nitrogen (LN) was sprayed. Results: When EM heating was applied, the center cooling time of the garlic cloves from freezing until $-10^{\circ}C$ was 48 s, which was approximately half the value of 85 s obtained without EM heating. For the white radish cubes, the center cooling time was also improved, from 288 to 132 s. The samples frozen by LN spray with EM heating had a closer hardness to the unfrozen samples than the samples frozen by LN only. Conclusions: The EM heating during quick freezing functions to maintain the hardness of fresh food by reducing the freezing time from 0 to $-10^{\circ}C$.

• Microbiology and Biotechnology Letters
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• v.25 no.1
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• pp.96-101
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• 1997

Among the lactic flora responsible for the development of acidity and characteristic flavor of Kimchi which is a traditional fermented Chiness cabbage. Homofermentative Lactobacillus plantarum is rod-shaped and to be known to ewert major role during later fermentation period. Once this strain establishes main flaora in the Kimchi fermentation process, it gives rise to excess acid production to reduce the taste and quality of Kimchi during storage. As a primary work to increase the keeping quality using virulent Lactobaillus plantarum bacteriophages, it was isolated sucessfully from collected Kimchi samples and their characteristics were studied. The new isolated phage, named SC 921, adsorbed to its host without Ca$^{2+}$, and nearly eliminated at 60$\circ $C of heat treatment for 5 min. This phages were atable at pH 4~ 10 but inactivated below pH 3.0 or pH 11.0 above. The latent period, rise period, and burst size of this phage was 100 min, 120 min, 31$\pm $2pfu/ml, respectively. Electron micrograph showed the phages particles were unusually oval feature of head (dia 80~ 120 nm) without contractile tail.