• Journal of Radiation Protection and Research
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• 제40권3호
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• pp.155-161
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• 2015

Radon is a naturally occurring radioactive gas and a major indoor contribution of exposure to ionizing radiation in dwellings. $^{222}Rn$ is a health hazard gas what is responsible for thousand lung cancer deaths every year. In this study, indoor radon concentrations present in thirty representative houses in Mahallat city, Iran, were determined in order to estimate lung cancer risk associated with residential radon exposure. Long-term passive method, using CR-39, was used to measure the radon concentration. The results showed an association between the age of the dwellings and the indoor radon concentration that was found, in that the concentration of radon tended to increase as the age of the dwelling also increased. The indoor radon concentrations were calculated to be within the range of $23{\pm}2$ to $350{\pm}26Bq{\cdot}m^{-3}$, with an average of $158Bq{\cdot}m^{-3}$. The annual effective dose from inhaled radon and its decay products was calculated between $0.8{\pm}0.1$ and $12.3{\pm}0.9mSv{\cdot}y^{-1}$, with an average of $5.5mSv{\cdot}y^{-1}$. By taking into consideration the EPA recommendation and ICRP statement, the average annual risk of lung cancer from inhaled radon was calculated as 0.09%, 0.06%, 0.01%, and 0.03% for current smokers (CS), those who had ever smoked (ES), never smokers (NS) and the general population, respectively.

• 교육시설
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• 제14권1호
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• pp.52-57
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• 2007

Kindergarten children are engaged in the age of physical immaturity as well as the rapid growth. The indoor air contaminants that are proved to affect even the full grown adults are obvious to have no little influence to immature small children in a growth period. In May 2004, for the multi purpose facilities and newly constructed apartments, the Ministry of Environment announced "Indoor Air Quality Control Law for the Multi Purpose Facility," which made the interests to be focused in the urgent understanding of current condition and preparation of measures about the indoor air pollution. In Dec 2005, the law was revised to obligatorily notify the amount of Formaldehyde and Volatile Organic Compounds in the case of newly constructed apartments with more than 100 houses. However, since the kindergarten takes none of the classifications, even the current condition is not grasped although it is directly connected to the health of growing children. Therefore, the study aims to analyze indoor air pollution of one selected kindergarten in Incheon city.

• 대한가정학회지
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• 제34권3호
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• pp.283-290
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• 1996

The objectives of this study was to research and analyze the actual conditions of using air-conditioning, which will help to understand the households' demand on a air-conditioning. The target of this study was the households in the seoul area. The data was collected by considering housing type, size & heating systems. On the basis of these findings, are the result of the demand for air-conditioning. 1)The possibility of purchasing this air-conditioning was higher among the households with ￦1,000,000 monthly income. Especially, the households with ￦2,000,000 to ￦2,500,000 monthly income were the main class of the demand. 2)The possibility of purchasing it was higher from husband's age over 30. 3)Both apartment and detached house dwellers were high in purchasing it. 4)The bigger the house was, the higher the possibility of purchasing it. Also, the function and the condition of air-cleaning function, which was concerning most on the economic point of view.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.762-767
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• 2009

Some types of semi-Volatile organic compounds (SVOC) that are emitted from plastics used in building materials and household appliances have associated health risks, even at low concentrations. In this study, micro chamber method for measuring SVOC is introduced and SVOC such as di (2-ethylhexyl) phthalate and butylated hydroxyltoluene emitted a flooring material were measured using a micro chamber method. Airflow characteristics in a micro test chamber deeply depended on air exchange rate. From the evaluation using an index of air change efficiency, such as the air age and the coefficient of air change performance, a fixed air exchange rate of $1.5\;h^{-1}$ in the micro chamber is desirable.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.236-239
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• 2004

The ternary blended cement(TBC) which the ability of resistance for seawater, the effect of decreation of hydration heat of concrete and long-age strength are known to be superior to other types was used to derive the estimation function of 91-age strength, 28-age strength with 28-age strength, 7-age strength respectively by analyzing the characteristics of statistics of compressive strength. The sample specimens was made after testing the variations of slump, air-contents during 30 minutes for consideration of transportation period. The functions might be expected to be useful for construction smoothness and reasonable quality control of concrete with TBC.

• KIEAE Journal
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• 제4권3호
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• pp.195-202
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• 2004

This study focuses on the impacts of apartment building arrangements on the outdoor and indoor air quality - the efficiency of natural ventilation in the outside/inside area of an apartment with consideration to the characteristics of an air flow in outside area depending on the types of the arrangements, the main direction of the wind, and the outside wind pressure on the building facade. As indices to evaluate the efficiency of natural ventilation, the concepts of "Age of Air" and "Purging Flow Rate(PFR)" were used in this study. As indices to classify the efficiency of indoor natural ventilation, the mean values of the wind pressure differences between the front and the back elevations of an apartment building were used. The research showed that the PFR of each apartment building arrangement ranges from 0.867 to 3.253. The "minus-shaped" arrangement showed the highest PFR, 2.306; the "zigzag-shaped" arrangement measured 1.889; the "angle-shaped" arrangement measured 1.465, and the "square-shaped" arrangement measured 1.241. Depending on the direction of the wind, the pressure differences range extremely, with variations from 170% to 2300%. Thus, the indoor natural ventilation efficiency can be changed by the pressure differences of the wind, which are sensitive to the main direction of the wind even though the structure and planning of the apartment complexes are the same. Despite the same direction of the wind, even the efficiency can be diverse. This study showed how to predict the most beneficial apartment building arrangement for the profitable natural ventilation efficiency in each direction of the wind.

• 한국항공운항학회지
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• 제27권4호
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• pp.105-113
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• 2019

The commercial pilot retirement age has continued to 65 since the International Civil Aviation Organization(ICAO) amended the recommended age limit from 60. The target of this review is to analyse whether aged pilots have an increased age-dependent risk of medical incapacitation. Medical in-flight incapacitation is actually very rare event and the demonstrated annual incapacitation rate provides an acceptable risk within the criteria known as 1% safety rule for a pilot undertaking air transport operations while some controversies exist. There is a possibility that the accident rate has decreased due to the improved skill by increasing pilot's age. At the decision of flight or not for elderly airline pilot the interacting factors of personal health status, piloting experience and new flight environments should be considered to define job limit criteria than mere the age. Results of a survey led by airline pilot association in Korea shows 65% of airline pilots are willing to fly without any age limit and 87% agreed that age limit is worthy to extend beyond current standard on the basis of medical examinations. Only 11% agreed to maintain current age limit.

• 설비공학논문집
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• 제19권10호
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• pp.695-702
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• 2007

In this paper, the ventilation efficiencies of an underground sewage disposal plant were investigated for ventilating system without fan, ventilating system with eleven cross flow fans and ventilating system with sixteen cross flow fans by numerical method. It has been found that the air change effectiveness of the system without fan was predicted 0.44. It means that an additional ventilating equipment is needed to maintain good indoor air quality. For the ventilating system with sixteen cross flow fans, the air change effectiveness was predicted 0.55. The air change effectiveness of the ventilating system with eleven cross flow fans was predicted 0.51. It is known that the air change effectiveness above 0.5 is enough to eliminate pollutant and bad smell in the indoor. Therefore, it is recommended to select the ventilating system with eleven cross flow fans for the underground sewage disposal plant in an economic point of view.

• 설비공학논문집
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• 제14권7호
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• pp.543-551
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• 2002

Gravity ventilators allow the escape of the warm air and air contaminants due to both (either) buoyancy and (or) convection. As a natural ventilation strategy, various gravity ventilators can be installed on the roof. Ventilation efficiency could be affected by various parameters, such as, area of openings, wind velocity and incidence angle, temperature difference between inside and outside, and shape of ventilator. Especially, the shape of roof gravity ventilator might be one of influencing factors for the effective ventilation. The window type gravity ventilators are frequently installed instead of general (standard) gravity ventilator. However, the ventilation efficiencies of them were not proved yet. To compare the ventilation efficiency, general type ventilator and two window type ventilators were numerically tested. Mean age of air, temperature and CO concentration were predicted by using commercial CFD code, AIRPAK (Ver. 2.0) with various conditions. The predicted result showed that general type ventilator is more effective for natural ventilation than window type ventilators.

• 설비공학논문집
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• 제10권5호
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• pp.610-618
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• 1998

In this study, a tracer gas technique was used to measure ventilation effectiveness in a thermal environmental chamber simulating an under-floor air conditioning system. A tracer gas of $SF_6$ was injected in a supply duct using step-up and step-down methods. Local mean ages and room mean ages were calculated from the measured concentrations under isothermal and cooling conditions with and without diffusers. Ventilation effectiveness is found to be higher in cooling ventilation operations than in isothermal operations. Results also show that ventilation effectiveness is not significantly affected by a diffuser.