• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.1
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• pp.23-33
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• 2017

In this study, water and organic treatment efficiency and operating characteristics (temperature, salinity effect) were evaluated when food waste with high water content was treated by Bio-dying method. In addition, the optimum conditions for producing pellets for evaluating the decomposition products as SRF(Solid Refuse Fuel) after Bio-drying and evaluating the use value of SRF as a solid fuel were analyzed. As a result, the temperature, $CO_2$ concentration, organic matter removal rate and weight reduction rate according to the daily dose were about 86% and 68% at the input of 2.4 kg/day. The optimal food waste input was estimated to be 2.4 kg/day. As a result of the pellet molding and produce, Pellets can be produced within 10~25% of raw material water content. It was judged that the water content of 25%, which showed the best quality results in terms of external shape maintenance and strength. The high calorific value of SRF of decomposition products after Bio-drying was more than 3,500 kcal/kg.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.15-20
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• 2018

The objective of this study is to numerically investigate the thermal characteristics of an automobile exhaust-based heat exchanger for automotive thermoelectric power generation with various exhaust gas mass flow rates and temperatures. The heat exchanger for automotive thermoelectric power generation has a square-type pin installed inside, so the maximum amount of heat can be transferred to the thermoelectric element from the heat energy coming from the automobile exhaust gas. The exhaust gas mass flow rate changed from 0.01, to 0.02, to 0.03 kg/s, and the exhaust gas temperature changed from 400, to 450, to 500, to 550, to $600^{\circ}C$, respectively. A numerical simulation was conducted by using the commercial program ANSYS CFX v17.0. Consequently, the exhaust gas pressure difference between the inlet and the outlet of the heat exchanger is determined according to the flow rate of the exhaust gas. When the mass flow rate of the exhaust gas increased, the pressure difference between the inlet and the outlet of the heat exchanger increased, but the exhaust gas pressure difference between the inlet of the heat exchanger and the outlet did not vary with the exhaust gas temperature. Therefore, in order to obtain the maximum surface temperature from the heat exchanger, the exhaust gas mass flow rate should be lower, and the exhaust gas temperature should be higher.

• Journal of the Korean Ceramic Society
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• v.41 no.11
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• pp.797-803
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• 2004

The heat generation tests of SiC and MO$_2$ samples by use of a microwave heating system were carried out and UO$_2$+5 wt% CeO$_2$ pellets were sintered in a microwave furnace in an oxidizing atmosphere, by taking into account the characteristics of the microwave heating obtained from the heat generation tests. The characteristics of pellets sintered in a microwave furnace were analysed and compared with those of the pellets sintered in a conventional electrical furnace. The temperature of MO$_2$ pellets with microwave heating increased quickly with input power and the variation of output power depended on the reaction characteristics of SiC and MO$_2$ with microwave. The sintered density of UO$_2$+5wt% CeO$_2$ pellets sintered in the microwave furnace was lower about 2% T.D. than that of the pellets sintered in an electrical furnace with sintering parameters. The microstructure of pellets sintered in microwave furnace has a broader pore distribution but has a larger grain size than that of the pellets sintered in the electrical furnace.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.131-138
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• 2010

This research intends to analyze the basic characteristics of cements(hereinafter "CC") with affordable price and particle distribution effective as hydration heat face which are discharged at the outlet of smashing process of ordinary portland cement(hereinafter "OPC") manufacturing process such as fluidity, rigidity, temporary insulation temperature increase amount etc to review the potential of developing "CC" to 3 ingredients low heat cement that substitutes fly ash and blast furnace slag(hereinafter "BS"). As a result of experiment, fluidity tended to decrease with increase in CC substitution rate, and increase with increase in FA+BS substitution rate. Air amount tended to slightly decrease with increase in CC substitution rate, and decrease with increase in FA+BS substitution rate. Condensation characteristics were such that condensation time was delayed with increase in CC and FA+BS substitution rate. As for the temperature rising amount by temporary insulation, peak temperature decreased with increase in CC substitution rate and increase in FA+BS substitution rate in general, and thereafter, temperature tended to decrease slowly. Compressive strength decreased with increase in CC and FA+BS substitution rate, and as aging goes on, long term strength was equivalent to plain or higher. By and large, when FA+BS was substituted to CC, fluidity and air amount tended to decrease, but hydration heat face showed good reduction effects, suggesting possibility of development to 3 ingredients low heat cement.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.1
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• pp.82-91
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• 2019

In this study, in order to evaluate Hydration Heat Characteristics of mass concrete using ternary blended cement for large underground structures, the analysis considering the temperature history and the thermal characteristics inside the actual structure was performed. The results of the analysis are compared with the measured values to verify the reliability of the analysis and to evaluate the crack resistance performance. As a result of the measured the actual structure temperature, The adiabatic temperature rise coefficients K and ${\alpha}$ of the slab were $35.1^{\circ}C$ and 0.72, respectively, and the wall was analyzed as $29.3^{\circ}C$ and 0.67. The analytical results and the correlation coefficients(r) were 0.95 and 0.98, respectively. As a result of evaluating the crack resistance of slab and wall, the minimum crack index of slab and wall was 1.22 and 1.20, respectively. These results were found to satisfy the site management standards.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2482-2487
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• 2007

Numerical simulations are conducted for the analysis of a thermal mass air flow sensor with periodic heating pulses on silicon-nitride ($Si_3N_4$) thin membrane structure. This study aims to find the locations of temperature sensors on the thin membrane and the heating pulse conditions, that the higher sensitivity can be achieved, for the development of a MEMS fabricated mass air flow sensor which is driven in periodic heating pulse. The simulations, thus, focus on the membrane temperature profile according to variation of the flow velocity, heating duration time and imposed power. The flow velocity of the simulations is ranging from 3 m/s to 35 m/s, heating duration time from 1 ms to 3 ms and imposed power from 50 mW to 90 mW. The corresponding Reynolds numbers vary from 1000 to 10000.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.113.1-113.1
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• 2010

본 연구에서는 중 소형 SOFC에 적용할 수 있는 연료 변환 시스템으로 자체 기동 및 독립운전이 가능한 천연가스 자열개질(ATR) 반응기를 $10Nm^3/hr$급으로 개발하고자한다. 설계된 천연가스 자열개질기는 자열개질 촉매를 코팅한 금속 모노리스형 촉매체를 반응기 내에 장착함으로써 반응열을 신속하게 제거 또는 공급할 수 있는 시스템으로 구성되었다. 이는 금속 모노리스의 뛰어난 열전도 능력에 의해 반응기 내의 촉매층 전체 온도 분포를 균일하게 유지할 수 있는 저에너지형 자열개질 반응기이다. 또한 빠른 기동 특성을 실현하기 위하여 전기 발열식 촉매체(EHC ; Electically Heated Catalyst)를 장착한 start-up 시스템을 적용하여 천연가스 자열개질 반응기의 신속한 기동과 장치 간편화를 실현하였으며, 합성 syngas의 배열 회수를 위한 최적 열교환 시스템을 설계/적용함으로써 에너지 효율 향상을 도모하였다. 이와 같은 촉매 및 구조 시스템을 가지는 천연가스 자열개질 반응용 소형 연료변환 시스템을 원통형의 이중관 구조로 구성하고, 독립운전 모드로 개발함으로써 소형 SOFC의 연료 변환장치의 적용에 용이하게 하고자 한다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1617_1618
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• 2009

의료용으로 사용되는 조명은 의사가 환자의 환부에 대해 정확히 판단할 수 있도록 조명으로서의 역할을 할 수 있어야 한다. 이러한 이유로 의료용에 사용되는 조명은 일반 조명으로 사용되는 광원에 비해 보다 특별한 사양들이 요구되어 진다. 기존의 수술용 무영등으로 사용되어 지는 광원은 대부분이 할로겐이나 제논 램프를 이용한 광원이었다. 할로겐이나 제논 램프의 경우는 100-1,000시간 정도의 수명을 가지고 있다. 이러한 광원들은 환자의 환부에 유해한 영향을 미칠 수 있는 UV 파장을 발생한다. 제논램프의 경우는 광원의 특성상 많은 양의 발열을 포함한다. 이러한 수명 및 발열 등의 문제를 가지고 있는 광원을 LED로 대체할 경우 LED가 가지고 있는 장점들을 수술용 무영등에 반영할 수 있다. LED광원은 다른 광원에 비해 장수명의 광원이며 인체에 유해한 파장을 거의 발생시키지 않는다. 또한 고연색성의 조명을 구현할 수 있으며 친환경적인 조명으로 구현할 수 있다. 이러한 LED의 장점을 고려하여 의료용 조명에 적용한다면 기존의 많은 의료용 조명을 LED로 대체할 수 있을 것이다.

• KIEAE Journal
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• v.15 no.2
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• pp.117-122
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• 2015

Purpose: Generally, 30% of the total energy consumption in office building is used for artificial indoor lightings, and almost 75-85% of electric power in fluorescent and Light-Emitting Diode (LED) lightings can be dissipated as a form of heat into indoor environment. The heat generated by indoor lightings can cause the increase of cooling load in office buildings. Thus, it its important to consider indoor lightings as a heat and light source, simultaneously. Method: In this study, we installed two kinds of indoor lightings including fluorescent and LED lightings and measured surface temperature of both indoor lightings. In addition, we obtained ambient temperature of indoor space and finally calculated total heat dissipated from plenum area and surface of lightings. Result: Total indoor heat gain was 87.17Wh and 201.36Wh in cases of six 40W-LED lightings and 64W-fluorescent lightings, respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.505-508
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• 2008

In this study, temperature increase and strength development of concretes with different types of cement were investigated to construct dam drop spillway. For this purpose, boxes of 1${\times}$1${\times}$1m size with 4 different concrete mixtures were made. The types of concrete were Type I cement concrete, fly ash cement concrete and two type concrete with ternary cement, respectively. The temperature at each point were monitored in these boxes. Based on the Box test, hydration analysis of slab of 2.0m thickness was carried out. This paper presents these experimental and analytical results.