• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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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.

• 태양에너지
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• 제19권3호
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• pp.23-28
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• 1999

본 논문에서는 난방용 축열보드에 응용하기 위해서 미세캡슐을 함유한 축열블럭의 열성능 특성을 조사하였다. 상변화 물질인 $CH_3COONa{\cdot}3H_2O$를 미세캡슐 형태로 제조하였고 미세캡슐 함유량이 각각 10%, 20%가 되도록 시멘트 몰타르와 혼합하여 축열블럭을 제작하였다. 축열블럭의 축열 및 방열 특성을 분석하기 위하여 유량과 유입 냉각 온도를 변화시켰다. 실험결과를 보면 미세캡슐 함유량이 증가할 수록 블럭에 축열되는 축열량은 증가를 하였고 방열시간도 증가를 하였다. 그리고 방열과정시 유량이 증가하고 유입 냉각온도가 감소함에 따라 방열시간은 감소하였다. 순수블럭(0% 미세캡슐 함유량)은 방열과정시 총괄 열전달 계수는 시간에 따라서 일정하게 유지를 하지만 축열블럭에서는 시간이 지남에 따라 증가를 하였다.

• 한국의류학회지
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• 제32권6호
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• pp.991-998
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• 2008

본 연구는 상변화물질의 농도가 의복내 공기충의 온도변화에 미치는 영향을 연구하고자 하였다. 상변화물질로는 노나데칸을 사용하였으며 농도는 아크릴 바인더 대비 10%, 20%, 30%로 조절하여 면직물에 코팅처리하였다. 동적 열전달 측정장치인 Human-Clothing-Environment Simulator을 사용하여 고온에서 저온 이동시 다시 고온이동시의 의복내 온도변화를 측정하였다. 외부 환경온도는 고온은 34도, 저온은 5도와 10도를 하였으며 먼저 34도에서 한시간 동안 컨디셔닝한 후에 5도 또는 10도에 30분 동안 노출시켜 의복내 온도변화를 측정하였고 다시 34도에 노출시켜 30분동안 의복내 공기층에서의 상변화물질의 열적거동을 살펴보았다. 그 결과 상변화물질처리된 직물로 이루어진 의복내 공기층은 고온에서 저온이동시 상변화물질의 발열효과로 인해 미처리 직물보다 높은 온도를 나타내었으며, 저온에서 고온이동시에는 흡열효과로 인해 미처리 직물보다 온도상승이 느리게 나타났다. 농도가 증가할수록 상변화물질에 의한 발열효과는 증가하는 것으로 나타났으며 흡열효과의 경우에는 20%에서 큰 변화를 갖는 것으로 나타났다. 농도변화에 따른 미처리와 처리직물 사이의 차이를 보면, 10%에서 20% 증가시에 나타난 차이가 20%에서 30% 농도변화시에 나타난 차이보다 크게 나타났다. PCM 처리된 모든 직물들이 상변화를 겪는 것은 아니었으며 직물층에 따라 상변화를 하였고 최외곽층의 경우에는 상변화물질에 의한 흡열발열현상외에도 외부로의 열손실을 겪기 때문에 이에 대한고찰이 있어야하는 것을 알 수 있었다.

• Fibers and Polymers
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• 제7권1호
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• pp.12-19
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• 2006

For thermal adaptable fabrics, the polyurethane-urea microcapsules containing phase-change materials (PCMs: hexadecane, octadecane and eicosane) were successfully synthesized by interfacial polycondensation using 2,4-toluene diisocyanate (TDI)/poly(ethylene glycol) (PEG400)/ethylene diamine (EDA) as shell monomers and nonionic surfactant NP-12 in an emulsion system under stirring rates of $3,000{\sim}13,000$ rpm. The mean particle size of microcapsule decreased significantly with increasing the stirring rate up to 11,000 rpm, and then leveled off. The mean particle size increased with increasing the content and molecular weight (eicosane > octadecane > hexadecane) of PCMs at the same stirring rate. The mean particle sizes of microcapsules were found to decrease with increasing the NP-12 content up to 1.5 wt%, and thereafter increased a little. It was found that the melting temperature ($T_m$) and crystallization temperature ($T_c$) of three kinds of encapsulated PCMs and their enthalpy changes (${\Delta}H_m,{\Delta}H_c$) increased with increasing PCM contents. The encapsulation efficiencies (Ee) of hexadecane microcapsule linearly increased with increasing the content of hexadecane. It was found that the stable microcapsule containing 50 wt% of hexadecane could be obtained in this study. However, Ee of octadecane and eicosane microcapsules increased with increasing PCM's contents up to 40 wt%, and then decreased a little. By considering the encapsulation efficiency, it was found that the maximum/optimum contents of octadecane and eicosane microcapsules were about 40 wt%. By the dynamic thermal performance test, it was found that the maximum buffering levels of Nylon fabrics coated with hexadecane, octadecane, and eicosane microcapsules were about $-2.4/+2.9^{\circ}C,\;-3.6/+3.6^{\circ}C\;and\;-4.0/+4.7^{\circ}C$, respectively.

• 설비공학논문집
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• 제26권2호
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• pp.72-78
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• 2014

In a cold chain, the refrigerator is also employed for defrosting, by using an electric heater, which consumes 15% of the power for the system operation. In this study, the condensation heat of the refrigerant was suggested as the heat source of defrosting heat, instead of that from an electric defrost heater. The heat for defrosting was stored to a phase change material (PCM, NMP : $52^{\circ}C$) in thermal storage, and was periodically supplied to the evaporator by a circulation loop of brine. As a result, a defrost time by the PCM was obtained that was less than or equal to that by the electric heater. Moreover, power consumption during defrosting was saved by up to 99% of that of the electric heater.

• 공업화학
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• 제21권5호
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• pp.570-574
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• 2010

기존 단열재의 주된 기능은 단지 열전달을 차단하는 기능과 건물로부터 열손실을 줄여주는 기능만을 수행했다. 반면, 축열재는 특정온도 범위 내에서 열에너지를 저장 또는 방출함으로써 건물에너지 사용량을 절감할 수 있다. 축열 건자재는 실내 공기온도 변화주기를 효과적으로 조절하여 일정하게 온도를 유지시킬 수 있다. 결과적으로 냉난방시스템 기능을 효율적으로 향상시킬 수 있다. 본 연구는 건축자재로 많이 이용되고 있는 석고보드에 상변화잠열물질을 축열재로 첨가하여 그 물성과 열환경 특성을 파악하였다. 또한 축열 건자재를 활용할 때 발생가능한 문제점을 확인하였다. 마지막으로 TVOC와 HCHO 함량 분석으로부터 오염물질의 배출가능성을 조사하여 축열 건자재의 환경 친화도를 검토하였다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
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• pp.80-85
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• 2009

Mathematical modeling and performance simulation results were shown for the solar thermal storage system which used heat pipe. The thermal storage system was composed of thermal storage tank and charging/discharging heat exchanger with one by the heat pipes. Heat pipe heat exchanger was attached to system, and could carry out charging and discharging to thermal storage tank at the same time. Height of the thermal storage tank was 600 mm, and that of the charging/discharging heat exchanger was 400 mm. Length of the heat pipe was the same as the total height of thermal storage system, and outer and inner diameter were 25.4 mm(O.D.) and 21.4 mm(I.D.) respectively. Diameter of the circular was 43 mm(O.D.), and fin geometries were considered as the design parameters. High temperature phase change material(PCM), $KNO_3$ and low temperature PCM, $LINO_3$ were charged to storage tank to adjust working temperature. Total size of thermal storage system able to get heat capacity more than 500 kW was calculated and the results were shown in this study. Number of heat pipe was required more than maximum 500, and total length of thermal storage system was calculated to the more than maximum 3 m at various condition.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권6호
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• pp.297-301
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• 2006

In the present work, we investigate the characteristics of new composition material, chalcogenide $Ge_1Se_1Te_2$ material in order to overcome the problems of conventional PRAM devices. The Tc of $Ge_1Se_1Te_2$ bulk was measured $231.503^{\circ}C$ with DSC analysis. For static DC test mode, at low voltage, two different resistances are observed. depending on the crystalline state of the phase-change resistor. In the first sweep, the as-deposited amorphous $Ge_1Se_1Te_2$ showed very high resistance. However when it reached the threshold voltage(about 11.8 V), the electrical resistance of device was drastically reduced through the formation of an electrically conducting path. The phase transition between the low conductive amorphous state and the high conductive crystal]me state was caused by the set and reset pulses respectively which fed through electrical signal. Set pulse has 4.3 V. 200 ns. then sample resistance is $80\sim100{\Omega}$. Reset pulse has 8.6 V 80 ns, then the sample resistance is $50{\sim}100K{\Omega}$. For such high resistance ratio of $R_{reset}/R_{set}$, we can expect high sensing margin reading the recorded data. We have confirmed that phase change properties of $Ge_1Se_1Te_2$ materials are closely related with the structure through the experiment of self-heating layers.

• Journal of Biosystems Engineering
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• 제31권3호
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• pp.161-167
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• 2006

The purpose of this study is to find the optimal conditions of PCM slurry manufacturing equipment for saving the marketing cost and keeping the original quality of products. In addition, the characteristics of the movable container for shipping or distributing products is analysed. The major results are as follows. 1. PCM thermal storage system is designed with the conditions of temperature($-5{\sim}10^{\circ}C$), cold chain time(30 minutes), and one time usage(50 liter). This system includes tank, freezer, circulating pump, cycle type heat exchanger, swelling tank, equipment of supplying PCM supplying unit includes cold tank, cycle type heat exchanger, suction unit and control equipments, etc. 2. After ability test of PCM thermal storage system, it shows that the required freezing time of PCM thermal storage system is less than one of the previous system. The reason is that churn (top and bottom) and compulsion circulation are occurred simultaneously and unit cooler type method is better than chiller type method. 3. By the experiment of transportation latent heat container, it is decided that the best container is $K_1$ with latent heat temperature($0{\sim}5^{\circ}C$) and density(0.15%). However, for $K_l\;and\;K_2$, it is necessary more studies on latent heat thermal conditions and conditions of making method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.226-231
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• 2001

The purpose of this paper is to propose the experimental method of thermal properties of Phase Change Materials (PCMs) by using T-history method. As far, in order to measure the heat of fusion and specific heat of PCMs, conventional thermal analysis methods such as DSC and DTA have been used. Because these methods test very small samples, thermal properties of samples are usually different from those of materials consisting of several components. For these reasons, T-history method, the simple measurement method of the heat of fusion and specific heat of PCMs have been performed. In this paper, we investigated the thermal properties of low temperature PCMs(below $0^{\circ}C$) under the charging process by using T-history method. The results are compared to those of DSC method. The T-history method will be useful for selection of the best PCM from lots of candidates and development of new PCMs.