• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회B
• /
• pp.2828-2833
• /
• 2008

Water management is one of many operating parameters, which influences the performance and stability of a proton exchange membrane fuel cell (PEMFC). Local humidity condition including liquid water saturation has profound impacts on the distributions of overpotentials, current density, and membrane water content. Computational fluid dynamics simulations were conducted to investigate the effect of the inlet humidity variation on the performance of a PEMFC of $9\;cm^2$ active cell area with serpentine flow fields. The results showed that the performance of the simulated PEMFC remained at an almost same level when the cathode inlet humidity was changed from 100% to 60%, while reaching its maximum at air humidity of 80%. However, further decrease in the cathode inlet humidity below 40% started to significantly deteriorate the performance of the PEMFC. The variations of overpotentials, membrane water content, etc. due to the change in the cathode inlet humidity were also discussed.

• 한국입자에어로졸학회지
• /
• 제10권2호
• /
• pp.75-82
• /
• 2014

It is necessary to find out the reaction characteristics of $CaCO_3$ sorbent particles in air and $O_2/CO_2$ atmospheric conditions in order that an in-furnace desulfurization technique can be applied to oxy-fuel combustion system. In this study, rate of change of GMD(geometric mean diameter) and specific surface area of $CaCO_3$ sorbent particles reacted in DTF(drop tube furnace) experimental setup were analyzed to investigate the effect of particle size and humidity on the reaction characteristics of them. In air atmospheric condition, calcination process occurs actively within shorter residence times as the particle size increases. On the contrary, in $O_2/CO_2$ atmospheric condition, a calcination process is delayed as particle size increases. The increment of humidity accelerates calcination process in an air atmospheric condition and increase rate of calcination in an $O_2/CO_2$ atmospheric condition.

• 콘크리트학회논문집
• /
• 제13권4호
• /
• pp.305-313
• /
• 2001

본 연구에서는 콘크리트 열전도율의 영향인자에 대하여 TLPP원리를 응용한 QTM-D3 장비를 이용하여 실험을 실시하였고, 이들 실험결과를 이용하여 콘크리트의 열전도율을 예측하는 모델식을 제안하였다. 본 연구를 통하여 얻은 결론은 다음과 같다. 콘크리트, 모르타르 및 페이스트의 열전도율에 미치는 주요 영향인자를 구명하기 위해 본 연구에서 선택된 실험변수는 재령, 골재 함유량, 시멘트 함유량, 결합재 종류, 잔골재율, 시편의 온도 및 함수상태로 총 7가지이다. 이중에서 골재 함유량과 함수상태가 콘크리트 열전도율의 주요 영향인자임을 알 수 있었다. 그리고 시멘트 사용량이 많은 페이스트나 모르타르의 경우 시멘트 함유량이나 결합재 종류에 의해서도 열전도율이 영향을 받고 있다. 그러나 재령은 콘크리트의 열전도율에 큰 영향을 미치지 않음을 알 수 있었다. 콘크리트 열전도율에 주요 영향인자인 골재 함유량, 잔골재율, 시편의 온도 및 함수상태를 이용하여 콘크리트의 열전도율을 계산할 수 있는 모델식을 제안하였다.

• 한국환경보건학회:학술대회논문집
• /
• 한국환경보건학회 2003년도 Challenges and Achievements in Environmental Health
• /
• pp.174-176
• /
• 2003

A survey was conducted to investigate the sanitary condition of school kitchens in one region of Korea. A self-administered questionnaire recommended by the Korea Ministry of Education & Human Resources Development (MOEHRD) was offered to a random sample of dieticians of twenty-five elementary schools for food, sanitation and safety inspection of their kitchens. Air temperature, relative humidity, and airborne microbes in the kitchens were monitored during food preparation, processing and service. The inspection results showed their sanitary condition met the level B of the recommendation of the Korea MOEHRD. The range of air temperature of the kitchens was 21.4∼22.4$^{\circ}C$, and the range of relative humidity was 62.4∼69.6%. The microbiological evaluation of kitchen samples indicated aerobic plate count levels from 22.5 to 26.5 CFU/15 min. These results indicate that the levels of sanitary condition of kitchens in the schools were not satisfactory for safe foodservice although the inspection showed good results. This study suggests that the school kitchens should be monitored and strict inspection is necessary.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 추계학술대회 논문집
• /
• pp.467-470
• /
• 2000

This paper present the result of the investigation, electric properties of outdoor insulators with the difference of contaminated condition. In general, the humidity and the amount of soluble salts such as NaCl, MgCl$_2$are the most dominant factor. A mini-fog chamber with transparent acryl and the standard contamination solution with kaoline was used. The kaoline was applied with sprayer to get the specific ESDD and NSDD value, then the specimen was dried and installed horizontally. And to measure the leakage current and the ambient condition, such as relative humidity and temperature, a DAS system was developed with LabView. From the result, we could know the influence of contaminated condition. Contaminated area and pattern has a close relationship with the electrical properties of outdoor insulator.

• 센서학회지
• /
• 제15권3호
• /
• pp.205-210
• /
• 2006

Hydrophobic polymer [ex. Poly(vinylidenfluoride)] layer was coated on polyaniline (PANi) sensor to reduce the contamination humidity. The differences in sensitivity to methanol gas detection in various humidity condition between pure-PANi sensor and sensor coated with poly(vinylidenfluoride) polymer (PVDF) (coated-PANi sensor) were investigated. Considering the relation between the density of pore, which was coated on the layer of the PANi sensor, and sensitivity was investigated. To fabricate the porous PVDF layer on PANi sensor, poly(vinylalcohol) (PVA), which is water-soluble polymer, was used. Coated-PANi sensor was less affected by humidity compared with pure-PANi sensor. And higher density of pore on PVDF layer led to higher sensitivity.

• 한국가구학회지
• /
• 제20권6호
• /
• pp.599-604
• /
• 2009

For the search of unified law of moisture movement in wood, moisture distribution of Korean red pine at non-steady state was investigated. We assume that the equilibrium moisture content (EMC) in wood depends on only temperature and relative humidity, it can be control in temperature and humidity chamber. If temperature is constant and humidity or vapor pressure is changed with sin curve shape at adequate cycles, EMC in chamber can be changed as well with sin-curve shape. The setup condition of a non-steady state in humidity control chambers is a constant temperature at $20^{\circ}C$ and 15+10 sin ${\omega}t$ percent EMC. It can be found that the distribution of moisture in the specimen with varying relative humidity are illustrated various types. Moisture in wood is complicated and vibrates with the moisture sorption process. Considering a unified law of moisture movement in wood, it is considered that the most important fact is to search the method of precise diffusion & transfer coefficients.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2008년도 하계학술발표대회 논문집
• /
• pp.1225-1230
• /
• 2008

Recently the building material have been developed with the concept of controlling the indoor environment as well as the concept of emitting contaminants less. So, a lot of products with humidity control characteristics put it on the market. However, objective evaluation to these products doesn't work out. Thus consumers cannot obtain accurate information to these products. Therefore, we selected inorganic paint in the functionality materials and evaluated its humidity control characteristic in this research. We divided by four stages and evaluated this inorganic paint. The 1st and 2nd third experiments were executed on a natural condition and the fourth experiment was executed with humidity had been raised by using the humidifier.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2007년도 동계학술발표대회 논문집
• /
• pp.322-327
• /
• 2007

Dedicated outdoor air-conditioning(DOA) system that utilizes pre-cooling and desiccant dehumidification can be superior to conventional cooling and reheating system with respect to energy consumption and indoor thermal comfort. In this work, simulation has been conducted to study various factors that affect the performance of DOA. Dynamic simulation shows the transient variation of temperature and humidity as the on/off control logic is imposed. Exit humidity of process air and flow rate are varied to study the effect on exit temperature of process air, dehumidification quantity, required regeneration temperature and exit humidity of regeneration air. For an outdoor air condition of $28.5^{\circ}C$ temperature, 16 g/kg humidity ratio and 2000 cmh flow rate, the dehumidification efficiency is increased by 4.6% as the flow rate is doubled.

• Current Applied Physics
• /
• 제18권11호
• /
• pp.1375-1380
• /
• 2018

Atmospheric-pressure plasma has a great potential in many applications due to its simplicity rather than low pressure plasmas. In material processing, biomedical applications, and many other applications, the input power, gas flow rate, and the geometry of electrode have been mainly considered and studied as important external parameters of atmospheric-pressure plasma control. Besides, since the atmospheric-pressure plasmas are typically generated in an open air, the relative humidity is difficult to control and can change day by day. Therefore, the relative humidity cannot be ignored for plasmas. Thus, in this work, the atmospheric-pressure plasma jet was characterized by changing relative humidity, and it was found that the increase in electron density and OH radicals are due to Penning ionization between helium metastable and water vapors at higher humidity condition.