• Journal of Mechanical Science and Technology
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• 제18권6호
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• pp.1002-1009
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• 2004

Direct contact air conditioning systems, in which heat and mass are transferred directly between air and water droplets, have many advantages over conventional indirect contact systems. The purpose of this research is to investigate the cooling and heating performances of direct contact air conditioning system for various inlet parameters such as air velocity, air temperature, water flow rate and water temperature. The experimental apparatus comprises a wind tunnel, water spray system, scrubber, demister, heater, refrigerator, flow and temperature controller, and data acquisition system. The inlet and outlet conditions of air and water are measured when the air contacts directly with water droplets as a counter flow in the spray section of the wind tunnel, and the heat and mass transfer rates between air and water are calculated. The droplet size of the water sprays is also measured using a Malvern Particle Analyzer. In the cooling conditions, the outlet air temperature and humidity ratio decrease as the water flow rate increases and as the water temperature, air velocity and temperature decrease. On the contrary, the outlet air temperature and humidity ratio increase in the heating conditions as the water flow rate and temperature increase and as the air velocity decreases.

• Journal of the Korean Wood Science and Technology
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• 제42권1호
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• pp.49-57
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• 2014

최종함수율은 예비천연건조를 수행한 시험재에서 더 균일하게 건조가 가능하였으며, 예비천연건조 후 고온저습건조시 최종함수율은 초기함수율에 영향을 받는 것으로 사료된다. 재면할렬 억제 효과는 예비천연건조를 수행한 시험재에서 더 효과적인 것으로 조사되었으나, 예비천연건조 중 발생된 재면할렬에 의한 영향이 크기 때문에 예비천연건조 중할렬발생 억제가 중요할 것으로 판단된다. 부분엔드코팅은 내부할렬, 표면경화율, 비틀림, 수축율에 미치는 영향이 없는 것으로 조사되었다. 예비천연건조는 고온저습건조 중 내층에 발생하는 인장응력을 감소시켜 내부할렬의 발생을 매우 효과적으로 억제하고 표면경화율을 감소시키는 것으로 조사되었다. 비틀림의 경우 함수율감소에 따른 수축으로 인하여 비틀림의 정도가 증가되었다.

• 생물환경조절학회지
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• 제5권2호
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• pp.160-166
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• 1996

김등과 Kim등이 재발한 공정묘 생산용 풍동을 사용하여, 인공광하의 묘개체군내외에서 기온, 상대습도 및 포차(vapour pressure deficit) 등의 미기상 특성에 미치는 기류속도의 효과를 분석하였다. 기온차의 최고치가 초장 근처에서 나타났으며, 이러한 결과는 공정묘의 생육이 진행될수록 더욱 분명하게 나타났다. 묘개체군 내부에서는 배지 또는 엽으로부터의 증발산으로 인하여 개체군 외부에서의 기온에 비해서 0.7-l.4$^{\circ}C$ 정도 낮게 나타났는데, 기류속도가 낮을수록 기온차가 높게 나타났다. 묘개체군 내부의 상대습도 분포에 미치는 기류속도의 영향이 매우 큰 것으로 나타났다. 기류속도가 증가할수록 묘개체군 내외에서의 상대습도차는 작게 나타났는데, 이것은 기류속도의 증가에 따라 엽에서의 water potential이 감소되었기 때문인 것으로 판단된다. 배지표면으로부터의 높이가 증가함에 따라 포차가 증가하였다. 이와 같은 결과는 수증기 유속의 흐름이 상방향으로 이루어짐을 의미하는 것이다. 생육단계에 따른 포차의 변화는 엽면적 지수가 클수록 수직방향으로의 기울기가 크게 나타났다. 한편, 후부에서의 상대습도 및 포차는 중앙부에서 보다 약간 낮게 나타났다. 기류속도에 따라 묘개체군의 수직방향 및 기류진행방향으로 기온, 상대습도 및 포차의 기울기가 크게 나타났는데, 이러한 미기상 요소의 기울기는 묘개체군의 불균일 생장을 초래할 수 있다.

• 한국항해항만학회지
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• 제30권1호
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• pp.113-117
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• 2006

이 실험의 목적은 튜브형 증발관에서 입구 공기 속도, 온도와 상대 습도에 따른 서리층 생성의 비교 검토에 있다. 입구 공기 속도와 온도는 각각 $0.3^m/_s,\;0.6^m/_s,\;0.9^m/_s,\;15^{\circ}C,\;20^{\circ}C,\;25^{\circ}C$로 하였고, 상대 습도는 $70\%\~90\%$로 하였다. 그리고 일반적인 공조기용 열교환기에서의 서리발생 현상을 파악하기 위하여 냉각튜브의 온도를 $-15^{\circ}C$로 일정하게 유지하였다. 그 결과 공급공기의 상대습도, 유속 및 온도가 증가할수록 서리 생성량이 증가함을 알 수 있었다.

• 한국수산과학회지
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• 제21권1호
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• pp.16-20
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• 1988

다시마의 건조와 수축특성을 알기위한 기초자료를 얻고자 건조중인 다시마의 건조 및 수축특성에 미치는 채취부위, 공기의 온도, 상대습도 및 풍속의 영향에 관하여 실험한 결과를 요약하면 다음과 같다. 1) 다시마의 열풍건조과정은 항률건조 기간이 없이 바로 감률건조기가 나타났으며 이것은 다시 감률건조 1단계 및 2단계로 구분되었다. 2) 두께가 얇은 선단부가 기부보다 수축이 더 많이 되었으며 공기의 온도 $50^{\circ}C$, 상대습도 $30\%$, 유속 0.4m/s의 일정한 건조 조건하에서 다시마의 선단부, 중간부 및 기부를 120분까지 건조하였을 경우 수축율은 각각 $57.5\%,\;54.0\%,\;42.7\%$이었다. 3) 상대습도가 낮은것은 높은것에 비해 건조속도 및 수축속도는 빨랐으나 함수률 $20\%$까지 건조하였을 경우 수축율은 오히려 상대습도가 높은것이 증가하였다.

• 대기
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• 제18권2호
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• pp.137-146
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• 2008

This study examines one thermal index, perceived temperature (PT), over the Korean Peninsula during 2007 summer. Heat/cold stress has been described using air temperature and humidity for warm seasons and air temperature and wind velocity in the cold conditions, while PT is based on a heat budget model of the human body that considers air temperature, humidity, wind velocity and radiation effect regardless of climates, regions and seasons. PT is higher about $4-5^{\circ}C$ than air temperature in the summer. Humidity increases PT, while wind tends to reduces PT possibly by evaporation of water vapor. The geographical distribution of summer PT indicates that the lowest PT happened in the east central region, with the appearance of the highest PT in the inland of southern region in Korea. Although the latitudinal trend shows that PT decreases northward, inland PT is higher than that of coastal region. Compared to the heat index or the discomfort index that considers air temperature and humidity, PT represents distinctive regional characteristics of thermal comfort. The distribution of PT shows that it may be a useful thermal index for the assessment of thermal comfort or stress region in the Korean Peninsula.

• 설비공학논문집
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• 제20권5호
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• pp.304-313
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• 2008

This paper investigates the indoor-air-quality (IAQ) characteristics of the interior space equipped with system air-conditioner. The behaviors of individual variables such as temperature, humidity and concentration of carbon dioxide ($CO_2$) that influence on IAQ of the interior space were characterized under various cooling conditions by numerical and experimental studies. The numerical analysis predicting the temperature behavior of the interior space was conducted, and its results showed a good agreement with the experimental ones. The $CO_2$ concentration and humidity were measured and their time dependent behaviors were monitored and analyzed. From the results, it was found that there existed the differences of the time-dependent behaviors of IAQ variables according to the locations. In addition, it is demonstrated that the large discharge angle of $45^{\circ}$ made the temperature profile more irregular and the high discharge flow of 5.34 m/s produced similar temperature profiles at three different sensing locations. Finally, the humidity of interior space was less sensitive to the changes of the air cooling conditions than the case of temperature and the $CO_2$ concentration increase mainly depended on the number of individuals inside the space.

• Environmental Engineering Research
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• 제25권2호
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• pp.171-177
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• 2020

Removal through adsorption is the most widely used and effective treatment method for volatile organic compounds (VOCs) in exhaust gases. However, at high temperatures and humidity, adsorption is competitive due to the presence of moisture and unsmooth physical adsorption thereby deteriorating adsorption performance. Therefore, water adsorption honeycomb (WAH) and VOCs adsorption honeycomb (VAH) were prepared to improve VOCs adsorption at high temperatures and humidity. Adsorbed toluene amounts on single honeycomb (SH), containing only VAH, and combined honeycomb (CH), containing WAH and VAH, were determined. Further, the toluene adsorption rates of honeycomb adsorbents mounted on rotary systems, VAH-single rotor (SR) and WAH/VAH-dual rotor (DR) were determined. Toluene adsorption by WAH/VAH-CH (inlet temperature: 40-50℃; absolute humidity: 28-83 gH₂O/kg-dry air) was 1.6 times that by VAH-SH, and the water adsorption efficiency of WAH/VAH-CH was 1.7 times that of VAH-SH. The adsorption/removal efficiency of the WAH/VAH-DR (inlet temperature: 45℃; absolute humidity: 37.5 gH₂O/kg-dry air) was 3% higher than that of VAH-SR. This indicates that the WAH at the rotor inlet selectively removed water, thereby improving the adsorption efficiency of the VAH at the outlet.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.773-777
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• 2002

In this study, we analyzed the LPG and LNG sensitivity measurement and voltage variation using catalytic type gas sensor characteristics in catalytic combustion type gas detecter sensors. gas detector shall operate as intended when exposed for 24 hours to air having a relative humidity of 0~85 percent at a temperature of $20[{\mu}m]$ and humidity of 45 percent at a temperature of $-10{\sim}40[^{\circ}C]$ the gas detecter sensors are to be subjected to operation for 210 days in an area that has been detemined to be equivalent to a typical residential atmosphere with an air velocity of 50 [cm/sec]. The source of energy for a gas detector sensors employing a supplementary basic circuit is energized from a separate source of supply direct applied voltage 2.1[V], 2.2[V], 2.3[V]. As a result, it was confirmed that the relative humidity and temperature by regression each analysis, compared to the LPG characteristic graph and methane characteristics graph by a relative humidity of 0 ~ 85 [%] at a temperature range of $-10{\sim}40[^{\circ}C]$ show a similar linear pattern on the whore.

• 한국자동차공학회논문집
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• 제23권6호
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• pp.601-607
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• 2015

The friction material for automobile is manufactured by mixing several composites to stop the running vehicles. Friction characteristics are changed significantly according to the relative amount of the base materials. However, difference of friction coefficient is sometimes measured at the test for the same friction material. Nevertheless, the study for solving these problems is insufficient. In this paper, the friction tests were carried out by changing the external environment and processing condition when the main ingredients are fixed and also evaluated how the friction coefficient changes. The variables are cooling air speed, humidity (Relative humidity and Absolute humidity), scorching time, soaking time and pad area. And it is analytically considered which environmental factor mainly affects the characteristic of friction coefficient variation by experiment. It is expected that the results from this study can be very useful as a database for development of the friction material.