• International Journal of Air-Conditioning and Refrigeration
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• 제14권1호
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• pp.1-6
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• 2006

For the purpose of processing weather data for air conditioning equipment de sign in Busan area Korea, this study collected weather observations made by Busan weather Administration from 1970 to 2003, and then established external conditions for heating and air-conditioning design. For changes of temperature in external conditions for design, the highest temperature had little changed, whereas the lowest had been on the rise as the years went by through the 1970s, 1980s, 1990s, and 2000s, but insolation has a little lessened. Absolute humidity does not show a significant change but an incessant rise.

• 한국물환경학회지
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• 제36권1호
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• pp.14-28
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• 2020

Future climate change may affect the hydro-thermal and biogeochemical characteristics of dam reservoirs, the most important water resources in Korea. Thus, scientific projection of the impact of climate change on the reservoir environment, factoring uncertainties, is crucial for sustainable water use. The purpose of this study was to predict the future water temperature and stratification structure of the Soyanggang Reservoir in response to a total of 42 scenarios, combining two climate scenarios, seven GCM models, one surface runoff model, and three wind scenarios of hydrodynamic model, and to quantify the uncertainty of each modeling step and scenario. Although there are differences depending on the scenarios, the annual reservoir water temperature tended to rise steadily. In the RCP 4.5 and 8.5 scenarios, the upper water temperature is expected to rise by 0.029 ℃ (±0.012)/year and 0.048 ℃ (±0.014)/year, respectively. These rise rates are correspond to 88.1 % and 85.7 % of the air temperature rise rate. Meanwhile, the lower water temperature is expected to rise by 0.016 ℃ (±0.009)/year and 0.027 ℃ (±0.010)/year, respectively, which is approximately 48.6 % and 46.3 % of the air temperature rise rate. Additionally, as the water temperatures rises, the stratification strength of the reservoir is expected to be stronger, and the number of days when the temperature difference between the upper and lower layers exceeds 5 ℃ increases in the future. As a result of uncertainty quantification, the uncertainty of the GCM models showed the highest contribution with 55.8 %, followed by 30.8 % RCP scenario, and 12.8 % W2 model.

• 설비공학논문집
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• 제16권3호
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• pp.293-302
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• 2004

In this study the optimization of plate-fin type heat sink for the thermal stability is peformed numerically. The optimum design variables are obtained when the temperature rise and the pressure drop are minimized simultaneously. The flow and thermal fields are predicted using the finite volume method and the optimization is carried out by using the sequential quadratic programming (SQP) method which is widely used in the constrained non-linear optimization problem. The results show that when the temperature rise is less than 34.6K, the optimal design variables are as follows; B$_1$=2.468mm, B$_2$=1.365mm, and t=10.962mm. The Pareto optimal solutions are also presented for the pressure drop and the temperature rise.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
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• pp.285-290
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• 2009

The main thrust of this paper is to investigate acceptable supply air conditions of a dedicated outdoor air system (DOAS) for highrise apartment buildings. As for a typical $132-m^2$ apartment unit, it was assumed that centralized DOAS-Ceiling Radiant Cooling Panel was installed. Transient behavior and control characteristics of each system were modeled numerically using a commercial equation solver program. The optimized dew point temperature of the DOAS was discussed on the basis of the ASHRAE standard 62.1-2007 and the current Korean ventilation standard for apartments. It was found that the optimized dew point temperature of the DOAS supply air accommodating total latent load of a space is $11-12^{\circ}C$ and the appropriate supply air temperature of the DOAS is $11-12^{\circ}C$ in cooling period and neutral temperature of $18-20^{\circ}C$ in intermediate period.

• 전기학회논문지P
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• 제64권4호
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• pp.256-260
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• 2015

In this paper, achieved rise temperature distribution about degradation phenomenon of 24 MVA distribution cast resin transformer using CFD(Computational Fluid Dynamics). Usually, life of transformer is depended on temperature distribution of specification region than thermal special quality of transformer interior. Specially, life of transformer by decline of dielectric strength decreases rapidly in case rise by strangeness transformer interior hot spot temperature value permits. Because calculating high-voltage(HV) winding and low-voltage(LV) winding of cast resin transformer and Joule's loss of core for improvement these life, forecasted heat source, and HV winding and LV winding of cast transformer rise temperature distribution of core for supply of electric power and temperature distribution of highest point on the basis of the results. Also, calculated temperature rise limit of cast resin transformer and permission maximum temperature using analysis by electromagnetic heat source. Calculated and forecasted rise temperature distribution by heat source of thermal analysis with calculated result.

• 한국농림기상학회지
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• 제2권3호
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• pp.95-102
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• 2000

근래의 '춥지 않은 겨울'현상의 연속출현으로 가을 보리의 재배지역의 북상에 따른 재배면적 확대를 논의 할 만하다. 최근('74∼'98년)의 가을보리재배기간(10∼5월)의 기상변화를 살펴보고 '87년을 기준으로 '춥지 않은 겨울현상'을 보인 13년('87∼'99년) 그전 13년('74∼'86년)의 가을보리 재배기간의 기상을 평년('61∼'90년)기상과 비교ㆍ분석한 결과는 다음과 같다. 1. 최근 25년 동안 가을보리재배기간의 평균기온은 1.02℃ 증가하였으며, 평균기온의 상승은 최저기온보다 최고기온의 상승이 더 크게 기여하였다. 2. 가을보리재배기간의 연도별 강수량은 최근 25년 동안 전국평균이 513.3 ㎜ 이었으며.'74년 이후 감소하다가 '92년 이후로는 다시 증가하는 경향이었으며, 일조시간은 농촌지역만 조금 적어지는 경향이고 다른 지역들은 조금씩 증가하는 경향을 보였다. 3. '춥지 않은 겨울' 현상을 보인 최근 13년의 가을보리재배기간의 기온은 평년보다 높았으며 특히 1∼2월의 기온이 많이 상승하였다 반면에 '87년을 기준으로 그전 13년의 기온은 평년과 비슷하거나 다소 낮은 경향을 보였다. 4. '춥지 않은 겨울'현상을 보인 최근 13년의 가을 보리재배기간의 강수량은 평년과 전반적으로 비슷하였으나, 4월의 강수량이 전국적으로 평년보다 26㎜정도 적었다. 반면에 일조시간은 전반적으로 평년보다 적었다 그러나, '87년을 기준으로 그전 13년의 강수량과 일조시간은 대체로 평년과 비슷하였다. 5. 가을보리의 안전재배선의 기준이 되는 월동기(1∼2월)의 기온상승으로 가을보리안전재배의 북상이 전망된다.

• 한국정밀공학회지
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• 제18권2호
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• pp.96-101
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• 2001

This paper shows the temperature characteristics of a high speed angular contact ball gearing which is 7004C type with ISO P2 tolerance class. A built-in motor type high speed spindle which adopts an oil-air lubrication system was used to measure the temperature rise up to 60,000rpm. The gearing temperature was measured using thermocouples that were attached to the outside surfaces of the outer rings. The result showed that the continuous test method which was suggested in this paper is more effective than on and off method and the lubrication oil supply rate should be reduced in high speed rolling bearings as long as the seizure does not occur. And the result were confirmed that the bearings packed with ceramic balls are superior to those with steel balls in temperature characteristics.

• 설비공학논문집
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• 제15권7호
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• pp.586-594
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• 2003

The performance of the condenser installed in the air-conditioning plant room of a high-rise building was studied numerically. The effect of the draft direction on the performance of an air-conditioner was analyzed. The on-coil temperature of the condenser was investigated by varying the arrangement and location o( the condenser in the air-conditioning plant room. The performance of an air-conditioner was also evaluated by using COP (coefficient of performance) and CGPI (condenser group performance indicator). The condenser in an air-conditioning plant room should be arranged in such a manner that the fan of the condenser is facing the outside of the building to exhaust the hot air directly, The model by which the condenser is located at the lower-left end of an air-conditioning plant room can prevent the hot air from reentering, and allow indrafting of fresh air. When the direction of draft is to the frontal face of the building, the performance of the condenser above 30th floor is degraded.

• 국제초고층학회논문집
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• 제5권4호
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• pp.327-338
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• 2016

This technical paper presents a detailed review of the stack effect phenomenon and of the associated implications pertaining to the design and construction of high-rise buildings in regions of extreme climatic conditions. The present review is focused on both the classical 'chimney' effect as well as on the reverse stack effect, which are respectively related to cold and hot climates. For the purposed of the work here presented, the ASHRAE (2013) design conditions of Astana (Kazakhstan) and Riyadh (Kingdom of Saudi Arabia) were selected. A 230 m tall residential building of rectangular floor plan was numerically modelled in the context of the climatic conditions of the two abovementioned cities and a number of sensitivity analyses were performed, covering parametric changes of: temperature, façade air tightness, site wind speeds and wind directions.

• 한국대기환경학회지
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• 제7권1호
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• pp.49-53
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• 1991

Relations of urban heat island and air pollution are analyzed by using $SO_2$ concentration data (winter season in 1985) from 10 sites of Seoul area and differences of wind speed and air temperature in urban and rural area. Urban heat island is developed when daily mean wind speed at urban site is lower than 1.5m/sec or in the interval of 3.0 $\sim$ 3.5m/sec. When differences between urban and rural air temperature is greater than the overall average of those differences, $SO_2$ concentrations of those above-average differences are 1.3 $\sim$ 1.8 times higher than those of below-average differences. The trends are shown obviously at north-eastern area of Seoul (Gilum Dong, Ssangmun Dong, Myeonmog Dong). When intensity of Urban Heat Island is weak, $SO_2$ concentration was reduced in propotion to a rise of wind speed. But $SO_2$ concentration is on the partial increase in spite of a rise of wind speed when intensity of urban heat island is strong.