• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2286-2291
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• 2008

Some electronics component, which is adopted as components of antenna for radar or satellite system and used for amplifying signals to transmit, is accompanied by very significant heat dissipation levels because of the inefficiencies inherent in radio frequency wave generation. So, proper cooling performance for that system is base requirement for thermal design. On this paper, we applied heat spreading structures to reduce thermal density and find the optimum values of heat sink design factors through theoretically, numerically and evaluated by product test. As the results, the performance of the cooling system shows the propriety of cooling high density heat dissipation electronics components.

• Fire Science and Engineering
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• v.21 no.1 s.65
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• pp.74-81
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• 2007

In this study, we have evaluated the hazardous factors of fires such as heat release rate, smoke density, ignition temperature, and flammability of carpet and curtain used in the public facilities. As a result of flame retardant treatment, the heat release rate of materials treated with flame retardant was lower than that of not treated. However, the smoke density of treated materials was higher than that of not treated. Also, we have investigated the fire characteristics of used and unused carpet. As a result, the heat release rate and the smoke density of used for 3 years carpet were higher than those of unused carpet. The distinct differences of flammability and ignition temperature between used and unused carpet were confirmed.

• Journal of the Korean Electrochemical Society
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• v.19 no.3
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• pp.114-121
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• 2016

This study investigates a CFD modeling of the charge-discharge behavior due to heat generation during charge-discharge cycles of a Li-ion secondary battery(LIB). Present LIB system adopted a current-density equation, heat and mass transfer governing equations upon the 1-dimensional system to the thickness direction for the rectangular pouch configuration. According to the 3-kinds of the charge-discharge current densities of 1C($17.5A/m^2$), 3C($52.5A/m^2$) and 5C($87.5A/m^2$) subject to a 3 V of cut-off voltage, a constant-temperature system at 298 K and three different heat generating systems were analyzed with comparison. Battery capacity decreases with increment of charge-discharge densities not only at the constant-temperature system but also at the heat-generating system. The time for charge-discharge cycles increases at the heat-generating system compare to the constant-temperature system. These trends are considered that the increase of temperature due to heat generation causes the decrement of equilibrium potential of electrodes and the increment of diffusivity of Li ions. Furthermore, cooling effects were discussed in order to control the influence of heat generation due to charge-discharge behavior of a Li-ion secondary battery.

• Korean journal of applied entomology
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• v.3
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• pp.15-19
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• 1964

1. The heat output by the insects, Oryzaephilus surinamensis, Tribolium confusum, Sitophilus zeamais and Sitophilus granarius, was investigated by reading the temperature of the inside of the grain in which the insects were developing in 2 Ib or 7 Ib jars incubated at $25^{\circ}C\; and\; 70\%$ R.H. 2. All the insects tested increase the temperature of grain, but the amount of heat produced by insects varies with the species of and the developmental stages of the insects. 3. It was found that all the temperature peaks correspond with the peak in number of the fourth instar larvae and the period in which the insects start to cause the heating corresponds to its 1 st and 2nd instar larvae. 4. Sitophilus spp. whose larvae live in the endosperm of the wheat produced more heat than Tribolium confusum and Oryzaephilus surinamensis whose larvae live on the grain. 5. Among the four species of insects, Sitophilus zeamais Produces the highest heat, followed by Sitophilus granarius, Tribolium confusum and Oryzaephilus surinamensis. 6. It is considered from the above results that the heat produced by insects seems to depend upon the species, the number and the age structure of population, and its its surroundings. 7. It is suggested therefore that when comparing the rate of development of insects kept at different densities. the effects caused by heating at the higher densities must be considered.

• Cement Symposium
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• s.36
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• pp.61-67
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• 2009

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.599-607
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• 2009

This study was conducted to derive the five correlations which could predict specific gravity(or heating value), compression factor, density, etc., if we know heating value or specific gravity only. To make a sufficient number of raw data for regression, SGERG EOS was modified into equation of heating value. Based on these raw data, five correlations were obtained and the uncertainties of the correlations were evaluated. The results showed that the uncertainties were near 0.1% in most conditions of natural gas and so the correlations could be used in natural gas industry and academic fields.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2009.04a
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• pp.520-525
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• 2009

본 연구에서는 실내 내장재료 많이 사용되고 있는 벽지를 대상으로 선정하여 연소특성을 고찰하고자 콘 칼로리미터, 연기밀도 시험기, 발화점 시험기, 산소지수 시험기를 이용하여 각각의 발열성, 발연성, 착화성, 난연성을 측정하였다. 벽지의 발열특성은 기능성 벽지인 쑥벽지와 특정벽지인 질석벽지가 다른 벽지에 비해 많은 열을 방출하는 것으로 나타났으며, 방염벽지의 연기밀도가 130.8로 가장 높은 값을 나타냈다. 질석벽지는 61초에 착화가 되어 다른 벽지에 비해 착화시간이 최소 4배 이상 늦게 착화가 되었으며, 발화온도 또한 270.8$^{\circ}C$로 높게 나타났다. 산소지수측정 범위는 18.9${\sim}$23.2%의 값으로 공기 중의 산소농도와 비슷한 범위인 것을 확인할 수 있었다.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.94-96
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• 2008

이차전지는 방전을 통하여 화학에너지를 전기에너지로 변환하여 사용하고 이의 역반응인 충전과정을 통하여 전기에너지를 화학에너지로 변환하여 저장함으로써 반복 사용이 가능하다. 많은 이차전지 중에서 리튬이차전지는 현재 핸드폰, 노트북, PDA 등 휴대용 전자기기가 보편화된 Mobile Energy 시대의 동력원이며, 최근 하이브리드 자동차, 지능형 로봇 등의 신산업분야에 적용하기 위한 고출력, 중/대형 이차전지의 개발이 활발히 진행되고 있다. 아울러 경쟁력을 확보하기 위해 전지부문에서는 에너지 밀도, 출력밀도, 사이클 수명, 안전성 등에서 지속적인 성능향상을 거듭하고 있으며, 활용면에서는 고밀도화에 따른 발열, 발화 사고의 안전성 문제를 해결하기 위해 배터리 보호회로를 필수적으로 장착하며, 이러한 보호회로는 용도에 따라 PCM(Protection Circuit Module), 스마트모듈(Smart Module), BMS(Battery Management System) 등으로 명칭되며, 각 사용분야별로 개발이 활발히 진행되고 있어 전지 시스템의 고안전성 및 고신뢰성을 추구하고 있다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.41.1-41
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• 2004

본 발표에서는, 최근 고속 고정밀 이송계로 각광을 받고 있는 리니어 모터의 열특성 분석과 구동부 설계변경을 통한 첨단 이송계의 열변형 억제 및 최소화 기술에 대해 다루고 있다. 리니어 모터의 공작기계에 적용 시, 리니어 모터의 발열원과 열전달 경로 등을 분석하고 이에 대응한 냉각기법과 단열재의 배치에 따른 고성능 이송계의 열특성 개선 사례를 소개한다. 새로운 리니어 모터의 공작기계에 적용은 선택사항에서 필수사항으로 이동한다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.677-680
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• 2008

The surface of particles was energetically modified by inter-grinding OPC and BFS in vibration mill for improvement of the early strength and low-heat evolution of concretes. BFS was pre-grinding in ball-mill to 2535(BS2) and 3245 $cm^2/g$(BS3), in blaine surface area. The inter-grinding time in vibration mill was changed from 10 minutes to 30 minutes. And Mixing ration of BFS to OPC was changed in 60, 70, 80%. After inter-grinding, the change of specific surface area, particle size distribution, hydration heat of cement and compressive strength of mortar were measured. As the result of comparison test with LHC, it was found that the mixture and inter-grinding time satisfying the value of over 100% of compressive strength for 7 days and under 170J/g of heat of hydration for 72 hours. and it was confirmed that the possibility of low heat slag cement utilizing blast furnace slag(BS2, BS3) with the low fineness in high volumes.