• 한국대기환경학회지
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• 제30권1호
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• pp.77-87
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• 2014

In this study, an experimental approach to measure a suite of low weight hydrocarbons was investigated with an emphasis on ethylene (EL) along with many others (ethane (EA), propane (PA), propylene (PL), n-butane (BA), acetylene (AL), methyl acetylene (ML)). Their concentrations were quantified using GC-FID system equipped with thermal desorption (TD) system. The TD-based analysis was conducted using both Link Tube/Thermal Desorber (LT/TD) method and Modified Injection through a Thermal Desorption (MITD) method. The results of these analyses were evaluated in a number of respects. The system allowed the detection of all compounds except methane with the mean response factor (RF) of 10.28 (EA) to 11.94 (PL). The method detection limits of target compounds were seen in the range of 0.027 (ML) to 0.146 ng (BA). The emission flux of some environmental samples (fruits), when measured using a small flux chamber system, fell in the range of 0.14 (AL: Kiwi) to $181ng{\cdot}g^{-1}{\cdot}hr^{-1}$ (EL: Apple Peel). The results of this study confirm that the experimental approach developed in this study allows to accurately measure emissions of low weight hydrocarbons (LWHC) like ethylene from various natural and man-made source processes.

• 방사선산업학회지
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• 제5권2호
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• pp.137-143
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• 2011

Epoxy resins are widely used as high performance thermosets in many industrial applications, such as coatings, adhesives and composites. Recently, a lot of research has been carried out in order to improve their mechanical properties and thermal stability in various fields. Carbon nanotubes possess high physical and mechanical properties that are considered to be ideal reinforcing materials in composites. CNT-reinforced epoxy system hold the promise of delivering superior composite materials with their high strength, light weight and multi functional features. Therefore, this study used multi-walled carbon nanotubes (MWNT) and gamma rays to improve the mechanical and thermal properties of epoxy. The diglycidyl ether of bisphenol A (DGEBA) as epoxy resins were cured by gamma ray irradiation with well-dispersed MWNTs as a reinforcing agent and triarylsulfonium hexafluoroantimonate (TASHFA) as an initiator. The flexural modulus was measured by UTM (universal testing machine). At this point, the flexural modulus factor exhibits an upper limit at 0.1 wt% MWNT. The thermal properties had improved by increasing the content of MWNT in the result of TGA (thermogravimetric analysis). However, they were decreased with increasing the radiation dose. The change of glass transition temperature by the radiation dose was characterized by DMA (dynamic mechanical analysis).

• 한국태양에너지학회 논문집
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• 제26권3호
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• pp.1-8
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• 2006

The objective of this research is to study on the analysis of long-term performance characteristics of various solar thermal system for heating protected horticulture system for reducing heating cost, increasing the value of product by environment control, and developing advanced culture technology by deploying solar thermal system. Long term field test for the demonstration was carried out in horticulture complex in Jeju Island. Reliability and economic aspect of the system which was operated complementary with thermal storage and solar hot water generation were analyzed by investigating collector efficiency, operation performance, and control features. Optimum operating condition and its characteristics were closely investigated by changing the control condition based on the temperature difference which is the most important operating parameter. However, it is expected that, in high-insolation areas where large-scale ground storage is adaptable, solar system demonstrated in the research could be economically competitive and promisingly disseminate over various application areas.

• 감성과학
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• 제17권3호
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• pp.95-106
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• 2014

본 연구에서는 다양한 실내 온열환경 및 조도에서 재실자가 느끼는 조명에 대한 감성의 변화와 작업의 종류에 따라 생체신호를 분석하여 업무에 미치는 영향에 대해 살펴보고자 하였다. 이를 위해 실내 온열환경은 PMV(predicted mean vote) 지표 값을 기반으로 환경을 구성하였고, 조명환경은 LED광원을 이용한 스탠드를 통해 조명의 밝기에 변화를 주어 다양한 실내 환경을 구성하고 실험을 진행하였다. 주어진 환경에서 설문지를 통해 조명에 대한 감성을 평가하고 종류가 다른 오류검색수정 작업을 진행하면서 뇌파와 심전도를 측정하여 변화를 분석하였다. 그 결과, 작업의 종류에 대한 모든 생체신호는 온열환경의 변화와 유의적인 차이를 보였으며, PMV 지표 값이 0.8(온도: $25^{\circ}C$, 습도: 50 %)일 경우 집중력 및 주의력이 가장 활성화 되었다. 하지만, 조도의 변화에는 대체적으로 유의적인 차이는 보이지 않았다. 따라서 재실자의 업무 능력에 미치는 집중력은 온열환경과 밀접함을 확인할 수 있다. 또한, 조명에 대한 주관적인 감성은 조도가 낮을수록 편안함을 느꼈으며, 조도가 높을수록 불편함을 느꼈다. 하지만 온열환경의 변화에는 유의적인 차이가 없었다.

• KIEAE Journal
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• 제3권1호
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• pp.31-36
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• 2003

Recently, buildings with transparent glazing on exterior walls have increased. The transparent glazing on exterior walls gives an impression of opening through introducing external environment's elements to inside of the building, and has various merits and so on, but has defects in controling indoor environments. Especially, the excess of solar radiation in summer increases cooling load causing discomforts to occupants providing radiant environment with high temperature. Cooling load mainly depends on electricity comparing to heating load and intents to centralize specific time. So it is necessary to work out a countermeasure. In this study, showed P building with transparent glazing on exterior walls as a case, investigated indoor thermal performance, numerical analysis of P building in summer through comparing dry-sauna which is represented as radiant environment with high temperature. In the results of this study, transparent glazing space has radiant environment with high temperature such as dry-sauna because of the excess of solar radiation. Accordingly countermeasures are considered in building planning. As concrete methods, there are adiabatic effects using double glazing, use of sunscreen, blind, ventilation facilitation using natural draft, decrease of surface temperature through evaporation cooling and cooling coils.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.510-515
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• 2003

High-speed machining generates concentrated Thermal/fractional damage at the cutting edge and rapidly decreases the tool life. This paper is aimed at improving the tool life using compressed chilly air. In this paper, the experiments were carried out in various cutting environments, such as dry, wet and compressed chilly air. Tool life were measured to evaluate machinability in high-speed milling of various materials. With respect to the cutting environment, compressed chilly air increased tool life. However, the wet condition decreased tool life due to the thermal shock caused by excessive cooling.

• 설비공학논문집
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• 제17권5호
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• pp.477-486
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• 2005

In this study, indoor thermal environment, resident behavior of operating cooling device, and thermal comfort vote are investigated at the living room of apartment during summertime in Seoul. Based on the results of the investigation, indoor air temperatures that residents turn air conditioners (especially for cooling load in this research) on and off were found out. The relationships between outdoor weather condition and the number of days using air conditioner, and whether operating patterns of the devices were also found out. The acceptable thermal comfort zone is figured out from these results, and this research is expected to contribute to the development of household air conditioner. The results can be summarized as the followings; Residents turned the air conditioner on at $29.76^{\circ}C$ of indoor air temperature, and $28.89^{\circ}C$ of $SET^\ast$. And turned the air conditioner off at $27.31^{\circ}C$ of indoor air temperature, and $23.70^{\circ}C$ $SET^\ast$. Therefore, acceptable thermal comfort zone could be lied between these temperatures. If comfortable indoor thermal environment can be obtained with various architectural passive cooling techniques based on the results, energy consumption of cooling devices will be reduced.

• 문화기술의 융합
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• 제9권6호
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• pp.883-888
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• 2023

데이터센터는 24시간 365일 IT 서비스를 제공하는 곳이기 때문에, 2030년에는 데이터센터의 전력 소비량은 약 10%로 증가될 것으로 예측되고, 고밀도 IT장비들의 도입이 점차 증가하면서, IT장비가 안정적으로 운영될 수 있도록 냉방 에너지 절감 및 이를 위한 에너지 관리가 갖춰져야 하기에 다양한 연구가 요구되고 있는 상황이다. 본 연구는 데이터센터의 에너지 절약을 위해 다음과 같은 과정을 제안한다. 데이터센터를 CFD 모델링하고, 인공지능기반 열환경 예측 모델을 제안하였으며, 실측 데이터와 예측 모델 그리고 CFD 결과를 비교하여 최종적으로 데이터 센터의 열관리 성능을 평한 결과 전처리 방식은 정규화 방식으로 사용되었고, 정규화에 따른 RCI, RTI 및 PUE의 예측값 또한 유사한 것을 확인할 수 있다. 따라서 본 연구에서 제안하는 알고리즘으로 데이터센터에 적용될 열환경 예측 모델로 적용 및 제공할 수 있을 것으로 판단된다.

• 한국환경과학회지
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• 제24권10호
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• pp.1265-1272
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• 2015

To investigate the thermal environment over the summertime asphalt pavements, an automatic weather observation system was installed at a parking lot paved with asphalt to observe various meteorological parameters and surface temperature from July 1 to September 30, 2014. Since the number of rainy days in summer of 2014 particularly after the mid July is more than that of average data, a ratio of daily peak surface temperature above $45^{\circ}C$ was 28% which was lower than the average. The observational data about hourly average surface temperature and various heat balance factors at days where daily peak surface temperature is above $45^{\circ}C$ are as follows: An hour that had the daily maximum temperature was around 15 pm and the value was $49^{\circ}C$ approximately. Net shortwave radiation was the highest at 12pm as $800W/m^2$ and much radiation of $500W/m^2$ was absorbed at the ground between 11am and 17pm. Sensible heat that was delivered from the ground to the atmosphere was evaluated as $200W/m^2$ between 10am and 19pm. underground transfer heat up to $100W/m^2$ was measured as negative from 19pm to the next day 8am, which indicated the lower atmosphere was heated at night.

• Journal of Biosystems Engineering
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• 제12권2호
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• pp.16-27
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• 1987

Greenhouse farming was introduced to the Korean farmers in the middle of 1950's and its area has been increased annually. The plastic greenhouse, which is covered with polyethylene or polyvinyl chloride film, has been rapidly spread in greenhouse farming since 1970. The greenhouse farming greatly contributed to the increase of farm household income and the improvement of crop productivity per unit area. Since the greenhouse farming is generally practiced during winter, from November to March, the thermal environment in the plastic greenhouse should be controlled in order to maintain favorable condition for plant growing. Main factors that influence the thermal environment in the plastic greenhouse are solar radiation, convective and radiative heat transfer among the thermal component of the greenhouse, and the use of heat source. The objective of this study was to develop a simulation model for thermal environment of the plastic greenhouse in order to determine the characteristics of heat flow and effects of various ambient environmental conditions upon thermal environments within the plastic greenhouse. The results obtained are summarized as follows: 1. Simulation model for thermal environment of the plastic greenhouse was developed, resulting in a good agreement between the experimental and predicted data. 2. Solar radiation being absorbed in the plant and soil during the daytime was 75 percent of the total solar radiation and the remainder was absorbed in the plastic cover. 3. About 83 percent of the total heat loss was due to convective and radiative heat transfer through the plastic cover. Air ventilation heat loss was 5 to 6 percent of total heat loss during the daytime and 16 to 17 percent during the night. 4. The effectiveness of thermal curtain for the plastic greenhouse at night was significantly increased by the increase of the inside air temperature of the greenhouse due to the supplementary heat. 5. When the temperature difference between the inside and outside of the greenhouse was small, the variation of ambient wind velocity did not greatly affect on the inside air temperature. 6. The more solar radiation in the plastic greenhouse was, the higher the inside air temperature. Because of low heat storage capacity of the plant and soil inside the greenhouse and a relatively high convective heat loss through the plastic cover, the increase of solar radiation during the daytime could not reduce the supplymentary heat requirement for the greenhouse during the night.