• Journal of Navigation and Port Research
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• v.31 no.10
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• pp.879-884
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• 2007

This study is to observe the change of temperature and relative humidity for various vegetables in vacuum precooling system. The materials for experiments were the lettuce, chinese cabbage, pak choi and cabbage. The experimental apparatus was constructed of vacuum chamber, vapor/water separator, water tank, pumps ejecting and cooling water circulation, refrigerator unit, cooling coil for water cooling, Hygrometer and Data logger measuring of the temperature change. The experiments were operated in 20torr and recorded every 3 minutes. It was found that the cooling temperature and speed of vegetables are depending on the percentage of its water content. The more water contains, the faster cooling speed and the lower cooling temperature.

• Journal of Energy Engineering
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• v.8 no.1
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• pp.159-165
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• 1999

복합화력 발전플랜트의 운전에서 특히 하절기의 첨두부하시에 외기온도의 상승으로 인한 가스터빈의 출력 감소를 해결하기 위한 방법으로 LNG 연료가 보유하고 있는 냉열을 이용하여 압축기로 유입되는 공기 온도를 감소시키는 냉각시스템의 개념을 개발하고자 복합화력 발전플랜트에 대한 설계점 및 외기온도 변화에 대한 탈설계점 모델링 연구를 수행하였다. 대상 프랜트는 940 MW 서인천 복합 발전플랜트 모듈의 단위 블록을 선택하였으며 발전플랜트 전용 해석코드인 GateCycle을 이용하여 가스터빈과 증기사이클의 주요 기기 들에 대한 모델을 개발하였다. 개발된 모델의 결과를 대상플랜트의 시운전결과와 비교하여 모델의 적정성을 검증하였다. 출력, 효율, 온도 및 유량 등 주요 설계인자들이 최대 ~1.3%의 상대오차 범위 안에서 만족할 만한 신뢰도를 갖는 것을 확인하였다. 탈설계점 성능해석은 본 논문과 관련한 연구의 주목적인 LNG 냉열에 의한 유입공기 냉각시스템 설계시의 경계변수인 외기온도 증가에 대한 각 사이클의 특성변화를 대상으로 하였다. 종합적으로 외기온도가 증가하면 압축기로 유입되는 공기의 양과 이에 대응하는 소요 연료량이 동시에 감소하므로 연소에 따른 가스터빈의 팽창비가 감소한다. 이로 인하여 외기온도 증가시에 가스터빈 출력감소율은 0.5%/$^{\circ}C$로서 배기가스를 이용하는 증기사이클의 출력감소율 0.2%/$^{\circ}C$에 비해 민감하므로 가스터빈 유입공기의 냉각시스템의 설계는 복합화력발전 플랜트의 효율 향상에 크게 기여할 것으로 예상된다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.1
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• pp.83-88
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• 2009

After storing green tea powder for three months at three different temperatures (-20, 4, and $20^{\circ}C$) with three different relative humidities (RHs) (23, 69, and 81%), the chemical quality was evaluated with green tea, which was prepared by soaking 1.5 g of the powder into 100 mL of distilled water at $70^{\circ}C$ for 5 min. Total phenolic contents, total flavanol contents, and ascorbic acid contents of green tea powder stored at $4^{\circ}C$ with 23% RH changed from 267.5, 49.4, and 24.2 mg/g to 287.1, 44.9, and 36.9 mg/g, respectively, compared to the powder before storage. EGC and EGCG, the main catechins of green tea, also changed from 16.9 and 27.3 mg/g to 24.3 and 36.5, g/g, respectively, after storage for 3 months at $4^{\circ}C$ with 23% RH. However, when the green tea powder was stored at -20 or $20^{\cric}C$ with higher RH such as 69 and 81%, the chemical compounds were significantly decreased. The results indicate that temperature and RH are important during storage of green tea powder, and low RH and refrigerated condition ($-4^{\cric}C$) are preferable to increase or preserve the chemical compounds of the tea.

• Magazine of the Korea Concrete Institute
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• v.10 no.3
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• pp.153-164
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• 1998

본 연구는 양생온도의 영향에 따른 콘크리트의 장기강도 예측식을 개발하고, 기존에 보고된 데이터를 이용하여 제안식의 신뢰성을 검증하기 위한 것이다. 제안식은 반응률상수 모델을 이용하였으며, 콘크리트의 장기강도에 영향을 미치는 인자로 양생온도에 따른 확산장벽의 효과를 고려하였다. 제안식을 검증하기위하여 각각의 데이터를 28일 상대강도의비로바꾸어 -0.6~59.7$^{\circ}C$ 범위의 8개의 평균 양생온도에 대해서 회귀분석하였다. 회귀분석을통해 제안식의 온도 영향계수인 반응율상수, 한계강도, 반응지수를 양생온도에 따른 함수식으로 표현하였다. 제안식은 기존의모델식에 비해 신뢰성이 높았으며, 초기재령에서는 기존의 모델식등과 큰 차이를나타내지 않았으나 장기재령으로 갈수록 제안식의 정확도가 크게 높아짐을 알 수 있었다.

• Journal of Korean Society of Forest Science
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• v.94 no.6
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• pp.468-475
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• 2005

To understand spatiotemporal changes of temperature and humidity in Lentimula edodes cultivation sheds, temperature, relative humidity were measured with HOBO H8 series sensors in log cultivation sheds and sawdust cultivation sheds. The results obtained from October in 2003 to October in 2004 were as follows; 1. Horizontal temperature changes were smaller at center of cultivation shed inside than comer of cultivation shed inside, while relative humidity changes were greater about 3% at center of cultivation shed inside than corner of cultivation shed inside. 2. Vertical temperature changes showed that the temperature was higher at above than at below when the temperature rises, while the temperature was lower at above than at below when the temperature falls. Thus close to soil surface temperature showed a little fluctuation. Vertical relative humidity changes showed that the relative humidity was lower at above than at below when the temperature rises, while the relative humidity was higher at above than at below when the temperature falls. After all temperature and relative humidity was the opposite in cultivation shed. 3. It's showed in log cultivation shed that the minimum temperature was a subzero temperature until the end of April, while the minimum temperature did above zero after the beginning of the May. Besides a winter was the greatest at daily temperature range during the four season, about $30^{\circ}C$. On the other hand the minimum relative humidity was less than 20% at April, May and June but more than 40% after May.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.758-765
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• 2016

This paper is a follow-up paper to the publication, "Development of Tunnel-Environment Monitoring System and Its Installation I - Monitoring System and Measurement in Subway Tunnel" [1]. An environment monitoring system was installed in the 20.3-km-long Gumjung tunnel, which has the general structure of a high-speed double-track railway tunnel. Data were collected for approximately one year. Monthly and daily data were obtained and analyzed for the temperature and relative humidity in summer and winter months. This paper discusses the environmental characteristics at different positions in the tunnel. The results are expected to be widely used in studies on tunnel ventilation and the improvement of air quality and thermal environments.

• Journal of the Korean Data and Information Science Society
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• v.27 no.6
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• pp.1601-1607
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• 2016

Recently, weather information has been increasingly used in various area. This study presents the necessity of hourly weather information for electricity demand forecasting through correlation analysis and multivariate regression model. Hourly weather data were collected by Meteorological Administration. Using electricity demand data, we considered TBATS exponential smoothing model with a sliding window method in order to forecast electricity demand. In this paper, we have shown that the incorporation of weather infromation into electrocity demand models can significantly enhance a forecasting capability.

• Journal of Bio-Environment Control
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• v.9 no.1
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• pp.60-64
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• 2000

This study was conducted to investigate effects of cooling methods on the growth and yield of tomato cv. momotaro in the glasshouse for four years from 1996 to 1999. Cooling methods were fan, fan and fogging, fan and shading(temp. control), fan and shading(radiation control), fan and shading (temp. control) with fogging. Fan, Fogging and Shading(temp. control) were operated automatically when air temperature was over 3$0^{\circ}C$. Amount of fogging was 500m1/min/100m$^2$and Droplets in a fog were 50 microns or smaller. Shading(radiation control) was operated automatically when solar radiation was over 500W/m$^2$. The growth and yield were the least in fan and shading(temp. control) method due to lack of light Intensity. Fogging method must be reconsidered for expensive equipment and maintenance expenses. As the matter stands, It is suggested to be the most considerable cooling method to increase ventilation rate with fan or use fan and shading(radiation control).

• The Korean Journal of Rheology
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• v.6 no.1
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• pp.10-19
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• 1994

에폭시수지와 CFRP 복합체 구조물의 경화공정 중에 발생하는 잔류응력은 구조물의 기계적물성에 영향을 미친다. 따라서 잔류응력을 낮추기 위해 여러 가지 방법들이 발표되고 있다. 이연구에서는 잔류응력을 낮추는 방법으로 잔류응력의 발새mechanism을 이해하고 반 응속도식과 여러 가지 기초물성을 기초로 한 computer simulation pro-gram을 이용하여 에 촉시수지와 복합체 구조물의 잔류응력을 최소화하는 경화공정을 찾는 연구를 진행하였다. 경화과정에서는 대부분의 경화온도가 구조물의 유리전이온도보다 높기 때문에 잔류응력이 발생하지 않고 대부분의 잔류응력은 냉각과정에서 발생하였다. 잔류응력을 정량화하는 방법 으로 구조물의 표면이 유리전이온도에 도달하였을때 내부 비체적분초를 상대적인 잔류응력 이라 간주하였다. 컴퓨터모사에 의해 최종경화온도와 냉각속도를 바꾸면서 잔류응력을 모사 한 결과 최종경화온도가 낮을수록, 냉각속도가 작을수록 잔류응력이 작게 발생하였다.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1998.04a
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• pp.270-274
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• 1998

HRV(heart rate variability)분석에 있어서 LF와 HF변수들은 교감신경계나 부교감신경계와 같은 인체내 자율신경계의 반응을 나타내는 유용한 지표로 사용되어져 왔다. 따라서 본 연구에서는 피험자나 실험환경의 상대적인 차이를 고려하여 상하온도차에 따라 변화하는 자율신경계의 반응을 HF/LF변수비를 통해 조사하였다. 전반적인 실험결과를 볼 때, 머리의 온도가 23˚인 경우 두한족열이 두열족한에 비해 HF/LF수치값이 대체로 높은 양상을 보여주었다. 두열족한의 경우 머리/발 온도가 $25^{\circ}C$/19$^{\circ}C$인 경우와 일부피험자를 제외한 27$^{\circ}C$/12$^{\circ}C$조건에서 높은 수치결과를 나타내었고, 두한족열에 있어서는 머리/발 온도가 2$0^{\circ}C$/26$^{\circ}C$인 경우와 23$^{\circ}C$/26$^{\circ}C$인 경우에 전반적으로 높은 수치결과를 보여주었다.