• 한국주거학회:학술대회논문집
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• 한국주거학회 2008년도 춘계학술발표대회 논문집
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• pp.281-284
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• 2008

The purposes of this study were to make clear the present condition of indoor thermal environment in apartment units and to analyze the relation of the living factors with indoor thermal elements. The field surveys consisted of measurements on physical elements and observations on living factors and interview on resident's subjective responses were carried out in 20 apartment units. The field surveys were carried out during the $January{\sim}March$ 2007. Measuring elements were air temperature, globe temperature, and relative humidity. As results, the averages of indoor temperature each houses were $21.2{\sim}27.2^{\circ}C$, the number of houses exceed the comfort zone were 4. The averages of globe temperature each houses were $21.3{\sim}27.5^{\circ}C$, 6 houses exceeded the comfort zone. The means of relative humidity were $19.5{\sim}58.8%$, relatively dry condition. The clothing value of residents were $0.39{\sim}0.89$ clo(average 0.68 clo). The average of thermal sensation ratings each room were $4.2{\sim}4.8$, 'neutral'$\sim$'slightly warm'. The results of regression analysis on relations of living factors with the thermal elements are as follow; ventilation time(outdoor air exchange), door opening time with balcony, and gas cooker use time had significant effect on indoor temperature.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.531-536
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• 2004

In-arm type hydropeumatic suspension unit(ISU) is an equipment of armed tracked vehicle to absorb impact load and vibration from the irregular ground. During the operation of ISU, main piston moves forward and backward and oil flowing through damper transmits the external impact load to floating piston. Heat is generated in ISU by the oil pressure drop through the damper orifice and the friction between cylinder wall and two pistons. On the other hand, internal heat dissipatis outside via heat convection. Occurrence of high temperature can deteriorate durability of major components and basic function of ISU. And, it can cause fatal problem in the ISU life time and the sealing performance of piston rings. As well, the spring constant change of nitrogen gas that is caused by the temperature rise exerts the negative effect to the vehicle stability. Therefore, in this paper, we analyze the heat transfer analysis of the entire ISU unit, by finite element method, with the outside flow velocities 8m/s and 10m/s.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.967-971
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• 2004

Today, as the demands for home appliances are increasing, the understanding of noise and vibration characteristics have become more important. It is hard to control its vibration and noise characteristics, because its mechanical structure is very complex. In this study a model of reciprocating compressor is developed. Spring, frame, and LDT are modeled as flexible body, and the other parts are modeled as rigid. FEM model of frame is simplified in order to save the simulation time. We validated the simple model by comparing their natural frequencies and mode shapes. Motor torque is applied to a rotor, and the piston is subjected to a gas pressure. The vibrational characteristics of compressor is analyzed with LS-DYNA. Its results are compared with the simulation results of rigid body frame. The effect of LDT is also studied by comparing the vibration of frame with the results of simulation with no LDT.

• 한국대기환경학회지
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• 제24권5호
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• pp.584-593
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• 2008

The surface $O_3,\;CO,\;NO_x,\;and\;SO_2$ were measured at Gosan in Jeju Island from May 2004 to April 2005. Over this period, the mean concentrations $({\pm}s.d.)$ of each gas was 40.06 $({\pm}16.01)$ ppbv for $O_3,\;264.92({\pm}115.73)ppbv\;for\;CO,\;1.98({\pm}2.73)ppbv\;for\;SO)_2,\;and\;4.64 ({\pm}3.24) ppbv\;for\;NO_x$. The monthly variations and the diurnal variations of these gases show that the Gosan site is situated in a relatively clean region. However, there were episodic simultaneous peaks in CO and $SO_2$, especially in winter and early spring. Using cluster analysis with air mass back- ward trajectory analysis, we suggest that these episodes are due to the influence of transportation of polluted air mass from polluted regions. In the cluster, which was under the dominant influence of clean maritime air mass, low levels of $O_3,\;CO,\;and\;SO_2$ were observed. The levels of these species were elevated in the other two clusters which had the air mass influenced by polluted continental regions. In addition, ratios of the chemical species such as $CO/NO_x,\;SO_2/NO_x,\;and\;CO/SO_2$ revealed the somewhat different characteristics of emission sources influencing each cluster. The differences in concentration of trace gases among clusters with different origin and transport pathways imply that Gosan is under the effect of pollution transported from other regions.

• 한국환경보건학회지
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• 제40권3호
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• pp.204-214
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• 2014

Objectives: Vehicular emissions are one of the main sources of air pollution in urban areas. Correlation analysis was conducted between air pollutants and traffic volume in order to identify causes of air pollution in Gwangju. Methods: Using traffic volumes and air quality monitoring data from 2002 to 2012 from nine stations (seven urban areas, two roadside areas), especially at three sites where traffic volumes were high, the correlation coefficients were obtained between air pollutants as PM-10 (particulate matter), $NO_2$, $SO_2$, CO and $O_3$ at the stations and traffic volumes near the air monitoring stations. Results: Due to traffic volume and distance between the station and the traffic road, concentrations of pollutants at roadside areas were higher than at urban areas, with the exception of $O_3$. The concentration of $O_3$ showed statistically significance with those of other gas materials as $NO_2$, $SO_2$, and CO in winter (p<0.001) and spring (p<0.05). During the period of October 7 to 20, 2012, excluding periods of yellow dust, smog and rainy season, the ratio of $NO/(NO+NO_2)$ showed the highest value 0.57 and 0.40 at Unam and Chipyeong of two roadside stations, followed by 0.35 at Nongseong with vehicular effects. The correlation coefficient between traffic volume and $O_3$, CO, $NO_2$ became higher when the data on mist and haze days were excluded, than when all hourly data were used in that period, at the three sites of Unam, Chipyeong, and Nongseong. Conclusions: Air quality showed a considerable effect from vehicles at roadside areas compared to in urban areas. Air pollutant diminishment strategies need to be aggressively adopted in order to protect atmospheric environment.

• 한국환경농학회지
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• 제2권2호
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• pp.114-119
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• 1983

채소(菜蔬)의 시설재배(施設栽培)에서 이상한파(異常寒波) 또는 보온(補溫) 및 가온열량(加溫熱量)의 불족(不足)으로 발생(發生)되는 저온장해(低溫障害)를 방지(防止)하고자 파라핀양초, 석유(石油)램프 및 전열선(電熱線)을 공시(供試)하여 보조가온(補助加溫) 시험(試驗)을 수행(遂行)한 결과(結果)는 아래와 같다. 1) 파라핀양초와 전열선(電熱線) 공중가설(空中架設)에 의(依)한 보조가온방법(補助加溫方法)으로 시설내(施設內)의 야간(夜間) 최저기온(最低氣溫) 강하(降下)를 방지(防止)할 수 있었다. 2) 파라핀양초와 전열선(電熱線) 보조가온(補助加溫)은 딸기에 장해(障害)를 보이지 않았고 생육(生育), 개화(開花), 수확(收穫)의 조기화(早期化)를 현저(顯著)히 촉진(促進)하였으나 총수량(總收量)의 증가(增加)는 인정(認定)되지 않았다. 3) 석유(石油)램프 보조가온(補助加溫)은 식물체(植物體)에 gas장해(障害)가 심(甚)하고 점등(點燈)과 소등(消燈)에 노력(努力)이 많이 들어 실화(失火)의 위험(危險)이 많고 연소(燃燒)에 의(依)한 악취(惡臭)가 심(甚)하여 가온재(加溫材)로서는 불적당(不適當)하였다. 4) 파라핀양초 보조가온(補助加溫)은 기상(氣象)의 예측(豫測)이 불정확(不正確)하므로 연료(燃料)의 낭비(浪費) 또는 가온열량(加溫熱量)이 불족(不足)한 경우(境遇)도 있으나 가온(加溫) 소요회수(所要回數)가 적을 때에 효과적(效果的)으로 사용(使用)할 수 있었다. 5) 전열선(電熱線) 보조가온(補助加溫)은 설치(設置)에 비용(費用)과 노력(努力)이 소요(所要)되나 온도(溫度)의 자동조절(自動調節)과 항온유지(恒溫維持)가 가능(可能)하므로 가온(加溫) 소요회수(所要回數)가 많을 때에 효과적(效果的)인 것으로 판명(判明)되었다.