• 공업화학
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• 제21권5호
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• pp.522-526
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• 2010

축열이용기술은 열저장효과를 이용하여 냉난방 부하가 적을 때 남는 열을 저장하였다가 부하가 증가할 때 이용하는 방법으로써, 열저장 물질의 온도이용 특성에 따라 현열축열과 잠열축열로 구분한다. 잠열축열은 특정 온도 범위에서 상변화 할 때 높은 잠열을 갖는 물질을 이용하여 열을 저장하는 방법으로 동일한 열저장을 위해 소요되는 공간 크기가 현열 축열에 비하여 작아지게 되고 일정한 온도범위에서 열의 흡수 및 방출이 가능한 특성이 있다. 본 연구는 건축물의 냉난방시 소요되는 에너지를 절약하기 위하여 상온 상변화물질을 축열재로 사용하여, 건축자재로 범용적으로 사용되고 있는 시멘트, 석고 등에 적용하고자 하였다. 제조된 물질이 에너지절약성능은 물론 건축자재로서 필요한 물성을 갖추기 위하여 최적배합 방법 및 비율을 도출하고자 하였다. 그에 따라 중량비로 3% 들어간 축열모르타르의 냉각지연효과는 약 19%로 나타났다.

• 한국산학기술학회논문지
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• 제13권4호
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• pp.1419-1426
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• 2012

KNU 식물공장 모델의 냉난방 에너지 부하를 DesignBuilder를 이용하여 해석하였다. 실내설정온도, LED 보광주기, LED 보광량, 유리외피의 구조에 따른 에너지 소모량을 분석하였다. LED 보광이 없는 식물공장의 실내설정온도를 상추의 적정 생육온도인 $20^{\circ}C$를 중심으로 $15^{\circ}C$, $25^{\circ}C$로 변화시키면서 일정온도로 유지하는데 필요한 연간 냉난방부하를 분석하였다. $15^{\circ}C$일 때 냉방부하, $25^{\circ}C$일 때 난방부하가 가장 크게 나타났다. 상추 재배에 필요한 LED 보광 적용 시 난방부하는 감소하지만 냉방부하가 약 6배 증가한다. 또한 LED 보광 시 주간보다는 야간보광이 냉난방부하 감소에 유리한 결과를 주었다. 식물공장 외피가 냉난방부하에 미치는 영향을 비교하기 위하여 다섯 가지 종류의 외피를 적용하여 계산하였다. 이중창호의 열관류율이 작을수록 식물공장의 난방부하는 감소하고 냉방부하는 증가하였다. 재배할 작물의 적정생장온도 설정, LED 및 재배설비의 내부발열량에 따른 적절한 외피선택, 다양한 패시브 및 액티브 에너지 절감기술의 적용으로 냉방부하를 감소시키는 것이 식물공장 운영에 중요한 요소로 판단된다.

• 한국환경과학회지
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• 제23권8호
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• pp.1437-1446
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• 2014

This study, the urban energy used office building green roof type composition of the target by analyze building energy reductions. Green roof is total 6 types(type A~F) were selected, EnergyPlus the energy simulation programs were used. Top floor of green roof types evaluation, the reduction of the cooling peak load type E(1.26%), type D(1.30%), type C(1.37%), type B(1.45%), type F(1.49%), and heating peak load is type D(1.32%), type E(1.40%), type C(1.47%), type F(1.69%), type B(2.13%) order. Annual cooling load of heating load is reduced more than about 1% effect. The heating load reduction ratio for a maximum of 9% respectively. Cooling peak load of the building energy performance evaluation of type F > type B > type C > type D > type E in the order and in the case of peak loads heating type B > type F > type D > type E>type C order. Annual total energy use reduction of 1.07 to 1.22% and earn, type B in the best good. In primary energy use reductions in the presence of a green roof were in the 4249~4876 kWh/yr. Annual $CO_2$ emissions reductions of unapplied type A were analyzed on average 469.78 kg.

• 한국태양에너지학회 논문집
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• 제32권3호
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• pp.138-145
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• 2012

Because of the climate changes and the development of building technologies, the cooling loads have been increased. Among the various renewable energies, geothermal energy is known as very useful and stable energy for heating and cooling of building. This study proposes a road snow-melting system of which heat is supplied from GSHP(Ground source heat pump) in viewpoint of the initial investment and annual running performance, which is also operating as a main facility of heating and cooling for common spaces. The results of this study is as followings. From the site measurement, it is found out that the road surface temperature above the geothermal heating pipe rose up to $5^{\circ}C$, which is the design temperature of road snow-melting, after 2 hours' operation and average COP(Coefficient of performance) was estimated as 3.5. The reliability of CFD has confirmed, because the temperature difference between results of CFD analysis and site measurement is only ${\pm}0.4^{\circ}C$ and the trend of temperature variation is quite similar. CFD analysis on the effect of pavement materials clearly show that more than 2 hours is needed for snow-melting, if the road is paved by ascon or concrete. But the road paved by brick is not reached to $5^{\circ}C$ at all. To evaluate the feasibility of snow-melting system operated by a geothermal circulation which has not GSHP, the surface temperature of concrete-paved road rise up to $0^{\circ}C$ after 2 hour and 40 minutes, and it does never increase to $5^{\circ}C$. And the roads paved by ascon and brick is maintained as below $0^{\circ}C$ after 12 hours geothermal circulation.

• Nuclear Engineering and Technology
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• 제40권6호
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• pp.467-476
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• 2008

To keep the superconducting (SC) magnet coils of KSTAR at proper operating conditions, not only the coils but also other cold components, such as thermal shields (TS), magnet structures, SC bus-lines (BL), and current leads (CL) must be maintained at their respective cryogenic temperatures. A helium refrigeration system (RRS) with an exergetic equivalent cooling power of 9 kW at 4.5 K without liquid nitrogen ($LN_2$) pre-cooling has been manufactured and installed. The main components of the KST AR helium refrigeration system (HRS) can be classified into the warm compression system (WCS) and the cryogenic devices according to the operating temperature levels. The process helium is compressed from 1 bar to 22 bar passing through the WCS and is supplied to cryogenic devices. The main components of cryogenic devices are consist of cold box (C/B) and distribution box (D/B). The C/B cool-down and make the various cryogenic helium for the KSTAR Tokamak and the various cryogenic helium is distributed by the D/B as per the KSTAR requirement. In this proceeding, we will present the commissioning results of the KSTAR HRS. Circuits which can simulate the thermal loads and pressure drops corresponding to the cooling channels of each cold component of KSTAR have been integrated into the helium distribution system of the HRS. Using those circuits, the performance and the capability of the HRS, to fulfill the mission of establishing the appropriate operating condition for the KSTAR SC magnet coils, have been successfully demonstrated.

• 한국태양에너지학회 논문집
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• 제35권2호
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• pp.93-101
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• 2015

Zero energy building is a self sufficient building that minimizes energy consumption through passive elements such as insulation, high performance window system and installing of high efficiency HVAC system and uses renewable energy sources. The Korea Government has been strengthening the building energy efficiency standard and code for zero energy building. The building energy performance is determined by the performance of building envelope. Therefore it is important to optimize facade design such as insulation, window properties and shading, that affect the heating and cooling loads. In particular, shading devices are necessary to reduce the cooling load in summer season. Meanwhile, BIPV shading system functions as a renewable energy technology applied in solar control facade system to reduce cooling load and produce electricity simultaneously. Therefore, when installing the BIPV shading system, the length of shadings and angle that affect the electricity production must be considered. This study focused on the facade design applied with BIPV shading system for maximizing energy saving of the selected standard building. The impact of changing insulation on roof and walls, window properties and length of BIPV shading device on energy performance of the building were investigated. In conclusion, energy consumption and electricity production were analyzed based on building energy simulations using energyplus 8.1 building simulation program and jEPlus+EA optimization tool.

• 한국생활환경학회지
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• 제21권6호
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• pp.959-964
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• 2014

Energy performance of building envelope components, including external walls, floors, roofs, windows and doors, is crutial for determining how much energy is required for heating and cooling in a building. Among various building technologies, a green roof system can be a good option for reducing heat gain and loss in new buildings as well as existing buildings for green remodeling. This paper evaluates the performance of green roof systems according to soil depth and Leaf Area Index (LAI) for existing buildings. It also attempts to quantify the energy saving effects on new and existing buildings with different insulation levels. Thermal performance of green roofs is mainly dependent on soil thickness and LAI. Installation of green roofs in deteriorated existing buildings can lead to improvements in roof insulation, due to the soil layer. An increase in soil depth leads to a decrease in heating load, regardless of conditions of vegetation on the green roof. Larger LAI values may reduce cooling loads in the cooling season. Installation of green roof in deteriorated existing buildings showed bigger energy saving effect in comparison to a case in new buildings. A simulation study showed that the installation of green roof systems in deteriorated existing buildings with low insulation levels, due to low thermal performance requirements when constructed, could improve the energy performance of the buildings similar or better to the peformance on new buildings with the most updated insulation standard. Thus, when remodeling a deteriorated building, green roofs could be a good option to meet the most recent energy requirements.

• 한국추진공학회지
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• 제15권5호
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• pp.1-9
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• 2011

비행체 속도를 증가시키기 위한 극초음속 항공기 기술 연구가 그동안 진행되어 왔다. 하지만 비행체의 속도증가는 비행체 구조의 변형을 유발할 수 있는 열적부하를 야기한다. 이러한 열적부하 처리를 위해 탄화수소형 흡열연료를 이용한 비행체 냉각에 대한 연구가 미국, 프랑스, 러시아 등 선진국에서 이루어지고 있다. 흡열연료(Endothermic fuels)는 열분해 또는 촉매분해와 같은 흡열반응(Endothermic reaction)을 통해 열을 흡수하는 액체 탄화수소 비행체 연료이다. 본 연구에서는 흡열연료의 모델연료로써 methylcyclohexane, n-octane, n-dodecane을 선정하여 흡열특성 연구를 진행하였다. 실험조건은 흡열연료가 사용되는 각 연료의 초임계 조건이며 온도별 분해율 분석, 열분해 생성물분석, 흡열량 계산을 수행하였다. 본 연구의 목표는 모델연료의 흡열특성을 규명함으로써 실제 비행체에 널리 사용되는 케로신 연료의 흡열특성 예측에 기여하는 것이다.

• 한국추진공학회지
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• 제18권2호
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• pp.10-15
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• 2014

극초음속 비행체는 속도가 증가할수록 공기와의 마찰열과 엔진열이 증가한다. 이러한 열적부하는 비행체 구조물의 변형을 야기하고 오작동을 유발할 수 있다. 흡열연료는 액체 탄화수소 연료로써 열분해 반응, 촉매분해 반응과 같은 흡열반응을 통해 열을 흡수할 수 있는 연료이다. 본 연구에서는 methylcyclohexane을 모델연료로써 선정하여 흡열특성을 측정하는 연구를 수행하였다. 반응열을 향상시키기 위해 제올라이트를 적용하였고 HZSM-5가 흡열량 향상에 가장 효과적인 것을 확인하였다. 본 연구의 목적은 흡열량 향상에 미치는 촉매의 영향을 연구하는 것이다. 이 촉매는 케로신연료를 흡열연료로써 사용하는 시스템에 적용될 수 있을 것이다.

• 한국물환경학회지
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• 제25권1호
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• pp.58-68
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• 2009

Low impact development (LID) technique is relatively new concept to reduce surface runoff and pollutant loading from land cover by attempting to match predevelopment condition with various integrated management practices (IMPs). In this study, computational model for designing and evaluating LID, named LIDMOD, was developed based on SCS-CN method and applied at Andong bus terminal to evaluate LID applicapability and design retention/detention area for volume or peak flow control. LIDMOD simulated with 21 years simulation period that yearly surface runoff by post-development without LID was significantly higher than that with LID showing about 2.8 times and LID could reduce efficiently yearly surface runoff with 75% reduction of increased runoff by conventional post development. LIDMOD designed detention area for volume/peak flow control with 20.2% of total area by hybrid design. LID can also efficiently reduce pollutant load from land cover. Pollutant loads from post-development without LID was much higher than those from pre-development with showing 37 times for BOD, 2 times for TN, and 9 times for TP. Pollutant loads from post-development with LID represented about 57% of those without LID. Increasing groundwater recharge reducing cooling and heating fee, creating green refuge at building area can be considered as additional benefits of LID. At the point of reducing runoff and pollutant load, LID might be important technique for Korean TMDL and LIDMOD can be useful tool to calculate unit load for the case of LID application.