• Title/Summary/Keyword: 절대습도

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Moist Air Density Calculation for Air Condition (공기 상태량에 대한 습공기 밀도 계산)

  • Kim, Jong-Woo
    • Transactions of the KSME C: Technology and Education
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    • v.2 no.2
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    • pp.105-111
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    • 2014
  • Generally the lower part of the Earth's atmosphere, which is 20km above the ground, is called "air." The composition of this area is almost consistent consisting of nitrogen, oxygen, and other gases. Air density refers to the mass per unit volume of earth atmosphere. Though air is made of the mixed gases in a constant composition, the water vapor is one of the very changeable components. The density of moist air is lower than the dry one at the same temperature and pressure. As the density varies according to the pressure and temperature, this paper attempts to explore the main factors in the air quantity calculation by examining first the density calculation process according to the air property, and second the relation between the actual and standard air flow.

Desiccant Dehumidifier Selection Program (데시칸트제습기 선정프로그램)

  • Kim, Hue-Jae;Park, Seung-Tae;You, Kyoung-Rok;Lee, Hyun-Ju
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.224-229
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    • 2009
  • Performance curve of the desiccant rotor is an important information when developing and selecting the desiccant dehumidifier. The effective utilization of the energy is major capacity for the system and the desiccant performance curve is a design ability for a designer. By the rotor supply contract with DRI, ECO-DRY programs would be offered. Moreover, it could make remarkable progress in the desiccant system and energy saving. It is good to introduce the programs with the amicable help of DRI.

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Standard Weather Data of Seoul for Energy Simulation (에너지 시뮬레이션을 위한 서울의 표준 외기 온도 및 습도 데이터)

  • 김성실;김영일
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.11
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    • pp.897-906
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    • 2002
  • Standard temperature and absolute humidity weather correlations of Seoul for dynamic energy simulation have been developed regressing the measured data compiled by the Korea Meteorological Adminstration during a 10-year period from 1991 to 2000. The mathematical equations can generate the daily and yearly variations of outdoor weather data with consistency unlike the measured data which may show abnormal behavior, Considering that each hour of the day follows a certain yearly pattern, the correlations are developed for each hour. The derived 24 simple mathematical equations can be used for estimating outdoor temperature and humidity conditions for any arbitrary time of the year.

Model for assessing the contamination of agricultural plants by accidentally released tritium (삼중수소 사고유출로 인한 농작물 오염 평가 모델)

  • Keum, Dong-Kwon;Lee, Han-Soo;Kang, Hee-Suk;Choi, Young-Ho;Lee, Chang-Woo
    • Journal of Radiation Protection and Research
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    • v.30 no.1
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    • pp.45-54
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    • 2005
  • A dynamic compartment model was developed to appraise the level of the contamination of agricultural plants by accidentally released tritium from nuclear facility. The model consists of a set of inter-connected compartments representing atmosphere, soil and plant. In the model three categories of plant are considered: leafy vegetables, grain plants and tuber plants, of which each is modeled separately to account for the different transport pathways of tritium. The predictive accuracy of the model was tested through the analysis of the tritium exposure experiments for rice-plants. The predicted TFWT(tissue free water tritium) concentration of the rice ear at harvest was greatly affected by the absolute humidity of air, the ratio of root uptake, and the rate of rainfall, while its OBT(organically bound tritium) concentration the stowing period of the ear, the absolute humidity of air and the content of hydrogen in the organic phase. There was a good agreement between the model prediction and the experimental results lot the OBT concentration of the ear.

A Study on the Effect of Air Humidity on the Performance of Gas Turbine Engine (가스터빈 엔진 성능에 습도가 미치는 영향 고찰)

  • 남삼식;전용민;양인영;김춘택;양수석;이대성
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2002.04a
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    • pp.24-24
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    • 2002
  • 가스터빈 엔진의 공력 성능은 작동 유체인 공기의 물성 변화에 대하여 민감하게 반응하는데, 대기 중에 수증기 형태로 함유되어 있는 수분이 공기의 물성 변화를 야기하는 대표적인 요인이다. 건공기와는 다른 화학적 조성을 가지는 습한 공기가 가스터빈 엔진에 유입되면 엔진의 작동과 성능에 2가지 방법(공기 흡입 도관에서의 응축 그리고 엔진 전체 사이클에 걸친 가스 조성 변화 야기)으로 영향을 미친다. 절대 습도가 높은 지상 조건의 무더운 날에는 습공기 유입으로 인한 가스터빈 엔진의 성능 저하가 두드러지며 지상에서의 고공환경시험에서는 시험 당일의 습도 조건에 따라 성능의 차이를 보인다. 해상에서 운용되는 비행체 추진기관으로 사용되는 가스터빈의 경우 특히 높은 습도 환경에서 작동하므로 습도 보정을 통하여 엔진의 정확한 성능과 운용성을 파악하는 것은 중요하다.

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A Study of the Characteristic of Friction Coefficient Variation for the External Environment (외부환경에 따른 마찰재의 마찰계수 변화 특성에 대한 연구)

  • Lee, Girhyoung;Lee, Dongkyu
    • Transactions of the Korean Society of Automotive Engineers
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    • v.23 no.6
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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.

Thermal Performance of an Enthalpy Exchanger Made of Paper at Different Outdoor Temperatures and Humidities (외기 온·습도 변화에 따른 종이재질 전열교환 엘리먼트 성능에 관한 연구)

  • Kim, Nae-Hyun;Lee, Eul-Jong;Song, Kil-Sup;Oh, Wang-Kyu
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.7
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    • pp.697-702
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    • 2010
  • An enthalpy exchanger in which heat and moisture transfer occur between the indoor and outdoor air operates at various outdoor conditions. In this study, the effect of the outdoor-air temperature and humidity on the performance of an enthalpy exchanger was experimentally investigated. An apparatus was specially-made to accurately measure the incoming and outgoing dry- and wet-bulb air temperatures as well as the flow rates. Tests were conducted in constant-temperature and constant-humidity chambers at different outdoor temperatures and humidities. It is shown that the effectiveness of latent-heat exchange increases as the relative humidity increases; further, this effect exhibited minimal dependence on the absolute humidity. However, the effectiveness of sensible-heat exchange is independent of both temperature and humidity

Evaluation of Measurement Accuracy for Unmanned Aerial Vehicle-based Land Surface Temperature Depending on Climate and Crop Conditions (기상 조건과 작물 생육상태에 따른 무인기 기반 지표면온도의 관측 정확도 평가)

  • Ryu, Jae-Hyun
    • Korean Journal of Remote Sensing
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    • v.37 no.2
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    • pp.211-220
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    • 2021
  • Land Surface Temperature (LST) is one of the useful parameters to diagnose the growth and development of crop and to detect crop stress. Unmanned Aerial Vehicle (UAV)-based LST (LSTUAV) can be estimated in the regional spatial scale due to miniaturization of thermal infrared camera and development of UAV. Given that meteorological variable, type of instrument, and surface condition can affect the LSTUAV, the evaluation for accuracy of LSTUAV is required. The purpose of this study is to evaluate the accuracy of LSTUAV using LST measured at ground (LSTGround) under various meteorological conditions and growth phases of garlic crop. To evaluate the accuracy of LSTUAV, Relative humidity (RH), absolute humidity (AH), gust, and vegetation index were considered. Root mean square error (RMSE) after minimizing the bias between LSTUAV and LSTGround was 2.565℃ under above 60% of RH, and it was higher than that of 1.82℃ under the below 60% of RH. Therefore, LSTUAV measurement should be conducted under the below 60% of RH. The error depending on the gust and surface conditions was not statistically significant (p-value < 0.05). LSTUAV had reliable accuracy under the wind speed conditions that allow flight and reflected the crop condition. These results help to comprehend the accuracy of LSTUAV and to utilize it in the agriculture field.

An Experimental Study on the Dehumidification Characteristics and the Effectiveness for Operating Conditions of a Desiccant Rotor (운전조건에 따른 제습로터의 제습특성과 유용도에 관한 실험적 연구)

  • Kang, Byung-Ha;Lee, Jin-Joo;Kim, Suk-Hyun
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.24 no.1
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    • pp.29-36
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    • 2012
  • An experimental study has been carried out to investigate the dehumidification characteristics for several operating conditions of a compact desiccant rotor. This problem is of particular interest in the design of a desiccant type of dehumidifier. Room temperature, room humidity, regeneration temperature, revolution speed and frontal air velocity of desiccant rotor are varied as operating conditions. The results obtained indicate that dehumidification rate is increased with an increase in the room humidity while dehumidification effectiveness is not changed much. It is also found that the optimal rotor speed and optimal regeneration temperature exist for maximum dehumidification rate and dehumidification effectiveness.

Design Temperature and Absolute Humidity for Peak Cooling and Heating Load Calculation with ETD Method (실효온도차법에 의한 최대열부하 계산용 온습도에 관한 연구)

  • Kim, D.C.;Seo, J.S.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.5 no.4
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    • pp.278-284
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    • 1993
  • A simplified TAC method was developed for the selection of design temperature and absolute humidity for peak cooling and heating load calculation with ETD method. And the design data of the 11 major cities in Korea were obtained. Based on the simplified TAC method, the design data for summer and autumn cooling season were selected by the TAC 5.0% of July through August and TAC 5.0% of October, respectively. But the design data for winter heating season were selected by the conventional TAC 2.5% of the full winter season.

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