• Title/Summary/Keyword: Room Air Ventilation

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Numerical Study on the HCFC-123 Leak in Turbo Chiller by using CFD (터보냉동기의 HCFC-123 누출에 대한 수치해석 연구)

  • Seo, Hoekyeong;Song, Sewook;Hwang, Yangin;Ha, Hyunchul
    • Journal of the Korean Institute of Gas
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    • v.18 no.5
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    • pp.85-90
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    • 2014
  • Turbo chiller is widely used for the air conditioner and uses hydrochlorofluorocarbon 123 (HCFC-123) as a refrigerant. HCFC-123 is one of the chemicals being considered as a replacement for the chlorofluorocarbons. High concentrations of HCFC-123 cause a deficiency of oxygen with the risk of unconsciousness or death, the vapour is heavier than air and may accumulate in low ceiling spaces causing deficiency of oxygen. In this study, the concentration distribution of oxygen indoor was investigated by using computational fluid dynamics(CFD) as four workers were killed in HCFC-123 gas leaks at machine room of hypermarket in 2011.

Characteristics of VOCs and Formaldehyde Emitted from Floorings (바닥재로부터 방출되는 휘발성유기화합물과 폼알데하이드 특성)

  • Park, Hyun-Ju;Jang, Seong-Ki;Seo, Soo-Yun;Lim, Jun-Ho
    • Journal of Korean Society for Atmospheric Environment
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    • v.25 no.1
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    • pp.38-45
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    • 2009
  • Since the seventies and the oil crisis, energy-saving measures have led to a reduction in the ventilation of room. The use of synthetic materials which emit various chemical substances had led to an increase in the concentration of indoor pollutants. "Sick building syndrome (SBS)" and "Sick house syndrome (SHS)" are worldwide problems. Also, the number of complaints about indoor air pollution caused by VOCs (Volatile organic compound) and HCHO (Formaldehyde) has increased. It is important that evaluating and understanding emission of indoor air pollutant from building materials. The object of this study was to evaluate emission test method for flooring such as wood based flooring, carpet tile, rubber tile, PVC sheet and tile, and to determine emission of TVOC and form-aldehyde. The quantity of TVOC and carbonyl compounds emission were sampled and measured by Tenax TA and gas chromatography/mass spectrometry (GC/MSD), 2,4-DNPH cartrige with ozone scrubber and high performance liquid from flooring. The TVOC concentration emitted from carpet tile was ($7.419\;mg/m^2 h$) the highest among 5 groups of test materials. In wood based flooring and PVC tile, the emitted concentration of toluene was high. And the dodecane emission was highest in carpet. The concentration of TVOC decreased by an increase in emission test period. After 7 days, the concentration of TVOC from floorings were about 50% below of the concentration at the first day. TVOC emission from wood based flooring, carpet tile, rubber tile, PVC sheet and tile were decreased in 28 days and remained steady after about 15 days. The concentration of formaldehyde emission from floorings showed extremely low.

Low Temperature Storage of Rough Rice Using Cold-Air in Winter (II) - Low Temperature Storage Characteristics of Rough Rice Using a Cooling System in the Top of a Bin - (겨울철 냉기를 이용한 벼의 저온저장 (II) - 빈상부 쿨링시스템을 이용한 냉각 벼의 저온저장 특성 -)

  • Lee, Jae-Seok;Hong, Hyun-Ki;Li, He;Park, Jong-Soo;Ham, Tack-Mo;Han, Chung-Su
    • Journal of Biosystems Engineering
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    • v.32 no.1 s.120
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    • pp.13-19
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    • 2007
  • Storage rough rice in low temperature using the winter cold air avoids rough rice temperature increase which happens from early May, and this is possible by installing a cooling system in the top of a bin, the room between top rice level and bin ceiling. The research objective is to establish low temperature rough rice storage technique, furnishing winter cold air to rough rice, by investigating the cooling system potential of maintaining low rough rice temperature and by analyzing rough rice storage characteristics over a storage period. The rough rice storage characteristics were evaluated from January to August 2003, using a storage and dry bin of 400-ton capacity. Results of this research are as follows: Cooling bin using the cooling system in the top of the bin maintained the rice temperature less than 15$^{\circ}C$ in entire portions in August. Moisture contents and germination rates of rough rice were decreased over the storage period, on the other hand, the rough rice stored in the ambient temperature bin had relatively lower moisture contents and germination rates to compare with the bin using winter cold air. Crack ratio and acid value of brown rice in the ambient temperature bin storage had increased more than the cooling bin storage. The result indicates that the storage bin using winter cold air and the cooling system maintains moisture content and germination of rice, minimizes cracked kernel and acid value, and preserves rice quality as well.

Observation of Changes in Indoor Formaldehyde(HCHO) Concentration during Ultrasound Guided Biopsy (초음파 조직생검 시 실내의 포름알데히드(HCHO) 농도 변화 관찰)

  • Lee, Hoon-Jeong;Kang, Sung-Jin
    • Journal of the Korean Society of Radiology
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    • v.15 no.7
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    • pp.1057-1064
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    • 2021
  • This study was conducted by simulating the same environmental conditions as the actual biopsy to observe the change in formaldehyde(HCHO) concentration in the indoor air during ultrasound guided biopsy. Changes in HCHO concentration in the room were measured by successively performing five steps: sealing the ultrasound room, ventilation, opening formalin containers, sealing formalin containers, and re-ventilating. Trends of measured HCHO concentration changes were visualized using graphs. As a result of analyzing the consistency of the concentration change values measured three times using the intra-class correlation coefficient, it was found to be 0.989, which was statistically significant(p<0.05). Based on the results of this study, we hope that medical workers working in the HCHO exposure environment of the field of radiology part will improve their awareness of the necessity of exposure management at work, and actively discuss the establishment of an environment for exposure control and preparation of countermeasures.

Monitoring of Formaldehyde Concentration in Exhibition Hall Using Passive Sampler (Passive Sampler를 이용한 유물 전시관내 폼알데하이드 농도 모니터링)

  • Lee, Sun Myung;Lim, Bo A;Kim, Seojin
    • Journal of Conservation Science
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    • v.33 no.5
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    • pp.319-329
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    • 2017
  • In this study, formaldehyde concentrations in two exhibition halls were monitored using a passive sampler from May 2012 to April 2013. Formaldehyde concentrations in the exhibition halls were 5 to 36 times higher than concentrations outdoors. Concentrations inside the exhibition room and showcase varied according to pollutant source, HVAC(heating, ventilation, air conditioning)system and environment management. The formaldehyde concentration levels were corrected according to a standard method prescribed by Indoor Air Quality Management Law of the Ministry of Environment, Korea. As a result, Most concentration levels exceeded the exhibition standard of the Ministry of Environment($100{\mu}g/m^3$) and artifacts conservation standard of Tokyo National Museum($50{\mu}g/m^3$). Seasonal concentrations in the exhibition room and showcase were in the order summer>fall>spring>winter. Formaldehyde emissions increased in summer when air temperature and relative humidity are both high. Formaldehyde concentration distribution according to the temperature and relative humidity showed positive correlation. Air temperature showed good correlation because $R^2$ was in the range of 0.8~0.9. Analysis of formaldehyde emission characteristics in the exhibition hall would be helpful in efforts to improve indoor air quality.

Development of Microprocessor-based Automatic Storage Controller and Temperature Auto-measurement System for Horticultural Crops (마이크로프로쎄서를 이용한 과채류 자동 저장 제어장치의 제작과 온도 자동계측 관리 시스템)

  • Park, Je-Kyun;Chun, Jae-Kun;Lee, Seung-Koo;Kim, Kong-Hwan
    • Korean Journal of Food Science and Technology
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    • v.20 no.6
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    • pp.845-849
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    • 1988
  • A laboratory scale storage facility consisting of a cold room, sample jars and a ventilation device was designed and built. Storaging sample jars (1.7 l) for fruit were fabricated with transparent acryl and provided with a constant air flow. For the supplying of air to sample jars, the air distributing system was built with solenoid valves, an air precooling coil and a pressure equalizing tank. To provide the programmable storaging environment of the facility a microprocessor-based controller was designed and installed. The controller was built with the 8 bit microprocessor (Z-80), EPROM, RAM, programmable peripheral interface(8255 PPI), and A/D converter. Softwares for the auto-temperature measurement and control of the storage system were developed and systemized in ROM. The automated storage system was applied to citrus storage, and the temperature of the storage facilities was successfully acquisited to the computer and controlled.

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A Study on Environmental Standards of School Building (교사환경기준에 관한 연구)

  • Hong, Seok-Pyo;Park, Young-Soo
    • The Journal of Korean Society for School & Community Health Education
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    • v.1 no.1
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    • pp.11-43
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    • 2000
  • The purpose of this study was, through analyzing the previous researches, to grasp the present status of environment of school building(ESB), research the sundry records of each element and, through comparative analysis of the standard of ESB in Korea, the United States, and Japan, select the normative standard of ESB, to clarify the point at issue presented in Regulation of Construction & facility Management for Elementary and and Secondary School in Korea, and to suggest an alternative preliminary standard of ESB. To carry out a research for this purpose, these were required: 1. to investigate the existing present status of ESB, 2. to make a comparative analysis of the standard of ESB in each country, 3. to suggest the normative standard of preliminary standard of ESB, 4. to analyze the controversial points of the standard of ESB in Korea, 5. to suggest an alternative preliminary standard of ESB. The conclusions were as follows: 1. Putting, through analyzing the previous researches, the existing present status of ESB together, it seemed that lighting environment, indoor air environment and noise environment were all in poor conditions. 2. In the result of a comparative analysis of the standard of ESB in Korea, Japan and the United States, in Korea the factors of each lighting and indoor air environment were not presented properly, in Japan, in lighting environment aspect, the standard on natural lighting and the factors on brightness were not presented., and in the USA the essential factors of each environment were throughly presented. In the comparison of the standards on each factor, Korea showed that the standard level presented was less properly prescribed than those of the USA and Japan but it also showed that the standard levels prescribed in the USA and in Japan were mostly similar to the standard levels in records investigated. 3. With the result of the normative standard selection on School Builiding environment factor of prescribed in this study, the controversial points of the standard of ESB in Korea were analyzed and the result was utilized to suggest new preliminary standard of ESB. 4. As the result of the analysis of the controversial points of the standard of ESB in Korea, it was found that the standard of ESB in Korea should be established on a basis of School Health Act and be concretely presented in School Health Regulation and School Health Rule. The factors of each environment was improperly presented in the existing standard of ESB in Korea. Moreover the standard of them was inferior to that of the records investigated and those of in the USA and in Japan and it also showed that the standard of it in Korea was improper to maintain Comfortable Learning Environment. 5. A suggested preliminary standard of ESB acquired through above study as follows: 1) In this study a new kind of preliminary standard of ESB is divided into lighting environment, indoor air environment, noise environment, odor environment and for above classification, reasonable factor and standard should be established and the controling way on each standard and countermeasures against it should be considered. 2) In lighting environment, the factors of natural lighting are divided into daylight rate, brightness, glare. In the standard on each factor, daylight rate should secure 5% of a mean daylight rate and 2% of a minimum daylight rate, brightness ratio of maximum illumination to minimum illumination should be under 10:1, and in glare there should not be an occurrence factor from a reflector outside of the classroom. And the factors of unnatural lighting are illumination, brightness, and glare. In the standard on each factor, illumination should be 750 lux or more, brightness ratio should be under 3 to 1, and glare should not occur. And Optimal reflection rate(%) of Colors and Facilities of Classroom which influences lighting environment should be considered. 3) In indoor air environment factors, thermal factors are divided into (1) room temperature, (2) relative humidity, (3) room air movement, (4) radiation heat, and harmful gases (5) CO, (6) $CO_2$ that are proceeded from using the heating fuel such as oval briquettes, firewood, charcoal being used in most of the classroom, and finally (7) dust. In the standard on each factor, the next are necessary; room temperature: $16^{\circ}C{\sim}26^{\circ}C$(summer : $E.T18.9{\sim}23.8^{\circ}C$, winter: $E.T16.7{\sim}21.7^{\circ}C$), relative humidity: $30{\sim}80%$, room air movement: under 0.5m/sec, radiation heat: under $5^{\circ}C$ gap between dry-bulb temperature and wet-bulb temperature, below 1000 ppm of ca and below 10ppm of $CO_2$, dust: below 0.10 $mg/m^3$ of Volume of dust in indoor air, and ventilation standard($CO_2$) for purification of indoor air : once/6 min.(about 7 times/40 min.) in an airtight classroom. 4) In the standard on noise environment, noise level should be under 40 dB(A) and the noise measuring way and the countermeasures against it should be considered. 5) In the standard on odor environment, odor level under Physical Method should be under 2 degrees, and the inspecting way and the countermeasures against it should be considered.

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A Study on Relationships Between Residential Environments and the Social Maturity of Middle School Students (중학생의 주거 환경과 사회적 성숙도와의 관계 연구)

  • Kim, See-Hee;Kwark, Kyung-Sook
    • Korean Journal of Human Ecology
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    • v.19 no.1
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    • pp.215-225
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    • 2010
  • This study had the purpose of presenting a residential environment solution as a desirable educational environment for middle school students to grow soundly and to achieve proper self-realization while providing basic materials to build up a suitable residential environment by comparing and analyzing what relationships exist between different home backgrounds, residential environments and middle school students' social maturity. This research was conducted from Feb. 11, 2008 to Feb. 13, 2008. The subject of this research was 601 students in 3 middle schools located in Gyunggi-do. The data analyzed used the SPSS 11.5 version. The summary of this study's results is as follows. First, in terms of home background, the higher the parents' educational background and social and economic position, the greater the students' social maturity. Second, in terms of home environment, the more spacious the living space, the better the water and sewage system and rest room, the more convenient the air conditioner and kitchen system, the better the lighting, ventilation, soundproofness, insulation, the less the danger in relation to fire, crime, traffic accidents, disaster, the greater the students' social maturity. Third, in terms of the home environment related to the correlation between the residential environment and social maturity, all areas such as housing facilities, housing structural environment and housing safety showed static correlations and proved that the residential environment has an important influence on social maturity. Accordingly, in order to build up an ideal residential environment, we should make efforts to expand and improve better facilities at home considering privacy, lighting, ventilation, soundproofness, heating etc. and remove unsound factors that obstruct students social maturity and build up clean and safe residential environment with good relations with their neighbors.

Effect of the Eave Width and the Vertical Rain Proof Facilities on Ventilation and Air Velocity Distribution in Hanwoo Loose Barn (개방한우사의 처마와 수직 비가림시설이 환기와 풍속 분포에 미치는 영향)

  • Lee, Seung-Joo;Jo, Hyeon-Jun;Kim, Dong-Hoon;Gutierrez, Winson M.;Chang, Hong-Hee
    • Journal of agriculture & life science
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    • v.45 no.4
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    • pp.87-93
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    • 2011
  • This study was carried out to determine more effective way in eave structure between lengthening roof just as standard plan and replacing 3 types of vertical rain roof facility by using computational fluid dynamics (CFD) simulation to reduce the heat stress of Hanwoo, increase the effect of dryness of room floor, rain proof and ventilation efficiency. The simulation which did with mean wind velocity (1.2 m/s) result showed that the case of lengthening of roof just as standard design was more effective than the cases of vertical establishment of rain proof facility.

Characteristic Analysis of Electret Filters made by Electrospinning (전기방사를 통해 제조된 정전기 보유 필터의 표면전위 및 대전량에 따른 성능특성 분석)

  • Kim, Gil-Tae;Ahn, Young-Chull;Lee, Jae-Keun
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.20 no.12
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    • pp.820-824
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    • 2008
  • Electret filter media are used in general ventilation filters, disposable respirators, vehicle cabin filters, vacuum cleaners and room air cleaners. There are basic mechanisms of interception, inertial impaction, diffusion, gravitational settling, electrostatic attraction by which an aerosol particle can be deposited onto a fiber in a filter. The ability of fine particle removal strongly depends on the electrostatic forces between particles and polarized fibers. Thus, the stability of the fiber polarization is a major factor in the reliability of electret filters. In this study, the electret filter is made by electrospinning process using Polystyrene which is dissolved by 5 : 5 of Tetrahydrofuran (THF) and Dimethylformamide (DMF). Also the electrical properties and the filtration performances of electrospun filter media are Quantitatively investigated. Electrical properties of electrospun filters have been studied on surface charge potential and surface charge density. Also the filtration performance of the electret filters are evaluated on collection efficiency. The surface charge potential and the surface charge density of electrospun PS filters are increased with increasing applied voltage and saturated at 30 kV of applied voltage. Also collection efficiency of electro spun filters is increased with increasing surface charge potential and surface charge density. But the surface charge potential is decreased by natural decay and it causes deterioration of particle collection efficiency.