• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.324-329
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• 2003

An air-conditioner has various noise sources such as cooling fan noise, pumping noise, flow noise and impact noise. Among these, impact noise is the most unpleasant source. This is because the noise is produced in indoor unit of air-conditioner. To control the noise source effectively, first we must identify the noise sources. When we identify impact noise source, the measurement have to be carried out simultaneously. So we use beamforming method that requires less measurement points than intensity method and acoustic holography. The objective of this paper is to estimate the location of impact source. This objective can be achieved by using minimum variance cepstrum that is able to detect impulse embedded in noise. In this study, modified beamforming method based on cepstrum domain is proposed. Then this method applied to air-conditioner noise sources which produce impact noise.

• Journal of Environmental Health Sciences
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• v.47 no.5
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• pp.398-409
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• 2021

Background: The types and effects of hazardous pollutants in indoor air may vary depending on the characteristics of the sources and pollutants caused by physical and chemical properties of buildings, the influence of outdoor air, and the exposure and use characteristics of residents. Objectives: This study was conducted to provide basic data on the establish of indoor air quality management for different classes of public-use facilities by presenting the characteristics of concentration distribution of hazardous pollutants by different public-use facilities and the status of the excess proportion of exceeding standards. Methods: This study analyzed self-measurement data from public-use facilities taken from 2017 to 2019 A total of 133,525 facilities were surveyed. A total of 10 types of pollutants that have maintenance and recommended standards stipulated in the Indoor Air Quality Control Act from the Ministry of Environment were investigated. The excess proportion and the substances exceeding the criteria for each type of public-use facilities for these pollutants were investigated. Results: As a result of the analysis of the proportion of exceeding the standard for each type of public-use facility, the facilities with the highest excess proportion of the standards for each hazardous pollutant were: PM₁₀ in railway stations (8.93%), PM_2.5 in daycare centers (7.36%), CO₂ in bus terminals (2.37%), HCHO in postpartum care centers (4.11%), total airborne bacteria in daycare centers (0.69%), CO in museums (0.1%), NO₂ in postpartum care centers (1.15%), Rn in museums (0.78%), total volatile organic compounds in postpartum care centers (7.20%) and mold in daycare centers (1.44%). Conclusions: Although uncertainty may arise because this study is a result of self-measurement, it is considered that this study has significance for providing basic data on the establishment in the future of indoor air quality management measures customized for each type of public-use facility.

• Journal of the Korean Institute of Gas
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• v.16 no.2
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• pp.31-37
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• 2012

This paper describes to analyze the ventilation performance of a room air conditioner for indoor comfort control. An experimental apparatus consists of a test room, the room air conditioner, a tracer gas measurement system, a supply fan and a controller. Ventilation performance as a function of human occupancy is evaluated with supply ventilation air using a tracer gas technique of CO2 gas in the test room. The ventilation performance is evaluated in a step-down method based on ASTM Standard E741-83 and is found to increase with increasing supply ventilation rate. The CO2 gas concentration is decayed rapidly without human occupancy. The ventilation performance without human occupancy increases up to 55% and the ventilation performance with one person increases up to 25% at the supply air of 570 lpm comparing with a natural reduction after one hour. A modeling for ventilation performance of a room air conditioner in a test room is presented using experimental datum.

• KIEAE Journal
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• v.6 no.1
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• pp.57-62
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• 2006

Korean Traditional houses has been evolved and developed in many years, adopting the natural environment to control exterior conditions. These control method are various passive system of using natural materials, considering micro climate, building lay out, and these system are more natural and ecological to make the comfortable indoor climate than active systems of the present houses. This study aims to analyzed control performance of outdoor environment of five Korean traditional houses during the summer and winter. These houses are varied with lay out and floor plan to reflect the way of control for environmental condition, surveyed the reverberation time and sound level difference between rooms of the main living room and other main floored room, master room and kitchen. Especially air temperature and humidity have been measured simultaneously in each rooms to compare with outdoor condition. As a result, the variation of air temperature and humidity of most rooms are considerably static while condition of outdoors are much varied, it is showed that indoor climate has been controled with traditional soiled walls.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.2
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• pp.142-148
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• 2007

The purpose of this study is to suggest the effective ventilation strategies and control methods that can minimize energy cost maintaining acceptable IAQ level in apartment house. The effects of the air-cleaning and heat-recovery ventilation system on IAQ under various operating conditions are investigated based on the experimental and CFD analyzed results. The results can be summarized as follows. (1) When a ventilator is not operated, the concentration of several pollutants may highly show in the house even though environment-friendly building materials are applied. Therefore, a mechanical ventilation system is required to obtain proper ventilation. (2) The pollutant concentration is noticeably deceased under air-cleaning/ventilation mode of air-clinic system, however, pollutant of kitchen is stagnant, because fresh air is not carried into the kitchen. (3) When air-clinic system is only equipped at master bedroom and living room, the system does not effectively deliver fresh air throughout the whole house, and then high pollutant concentration is obtained in each room. In contrast the average pollutant concentration meets the guideline when air-clinic system is installed at each room. (4) The air-cleaning/ventilation mode significantly affects on room ventilation in comparison with ventilation mode only.

• International Journal of Air-Conditioning and Refrigeration
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• v.12 no.2
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• pp.61-69
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• 2004

In this study, on-site performance test of an air source heat pump which has a rated capacity of 10 RT is carried out. Since indoor and outdoor air conditions can not be controlled to satisfy the standard test conditions, experiments are done with the inlet air conditions as they exist. To estimate the performance of the heat pump for other conditions, the heat pump is modeled with a small number of characteristic parameters. The values of the parameters are determined from the few measurements measured on-site during steady operation. A simulation program is developed to calculate cooling capacity and power consumption at any other arbitrary operating conditions. The simulation results are in good agreement with the experiment. This study provides a method of an on-site performance diagnosis of an air source heat pump.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2005.05a
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• pp.212-216
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• 2005

The purpose of this study is to make clear the indoor thermal environmental efficiency of indoor garden in apartment during winter. The questionnaire survey was carried out during the l0th${\sim}$20th of February 2004, respondents consisted of 215 residents living in a subject apartment estate. The field measurements of indoor thermal elements were carried out at A house with indoor garden and at B house without indoor garden. The measurements in two-subject houses were taken on simultaneously the 11th of February. As Results, the residents living in apartments with indoor garden show positive response on air moisture and satisfaction. The daily ranges of indoor temperature and globe temperature in the A house were narrower than the B house. The average relative humidity in the A house was higher and constant than the B house. Therefore, it was seemed that indoor environment during winter in the house with indoor garden maintained more constant or comfortable than the house without indoor garden by earning effect and humidity control effect of plants.

• Environmental Engineering Research
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• v.12 no.5
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• pp.203-210
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• 2007

Since the emissions composition from the household products have potentially been associated with health risks for building occupants, the chemical composition emitted from the products should be surveyed. The current study identified the emission composition for 42 liquid household products, using a purge-and-trap method. This evaluation was done by classifying the household products into five product classes (deodorizers, household cleaners, color removers, pesticides, and polishes). Nineteen compounds were chosen on the basis of selection criteria. The quality control program for purge-and-trap and analytical systems included tests of laboratory blank Tenax traps and blank water samples, and the determination of calibration equation, measurement precision, method detection limit (MDL), and recovery. The number of chemicals varied according to the product categories, ranging from 4 for the product category of bleaches to 12 for the product categories of air fresheners and nail color removers. For all product categories, the emission composition and concentrations varied broadly according to product. It is noteworthy that most household products emit limonene: 19 of 25 cleaning products; 5 of 6 deodorizers; 1 of 3 pesticides; 3 of 3 color removers; and 4 of 5 polishes. It was suggested that the use of household products sold in Korea could elevate the formation of secondary toxic pollutants in indoor environments, by the reaction of limonene with ozone, which entered indoor environments or might be generated by indoor sources such as electronic air cleaning devices and copying machines.

• Journal of environmental and Sanitary engineering
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• v.17 no.1
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• pp.36-40
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• 2002

The purpose of study was to suggest an investigation of citizen's attitude on harmful insects in house. This study was consisted of four parts, such as basic investigation (housing shape, housing material, the period of house constructed, a cleaning condition), condition of kitchen, condition of living room condition of bathroom. The environmental pollution was increased by the development of industry and urbanization in modern. And also the clean of house has related with air quality such as pollutants and harmful insects etc. Because dwelling shape of urban come to be crowded, shut tightly and high buildings, the air quality of indoor was gradually polluted by several irregular cause. In one of housing pollution, the harmful insects was important any other than indoor air pollution. The problems of kitchen were the odor of food waste, discharge system of sewage and harmful insects. The important issues of living room were mold and construction materials, then important them of bathroom were easing nature and discharge system of sewage. A kind of the harmful insects in house investigated cockroach> mosquito> ant>fly. Finally, it appeared that the control of harmful insects can be applied to the improvement of indoor air pollutant which are difficult to be controlled in house.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.7
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• pp.607-616
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• 2002

This study has been conducted to evaluate the applicability of the control method in the dehumidification-integrated radiant floor cooling system in terms of stability of the room air temperature and the control variables through experiments. To do this, the relationship between the control variables in preventing floor surface condensation is first analyzed and the control method is predetermined through simulations. The results are as follows. First, it is necessary to determine the operation status of the dehumidification system according to the relationship between floor surface temperature and dew point temperature in the conditioned space. Second, outdoor reset with indoor temperature feedback control is better than on/off bang-bang control with respect to temperature stability in controlling the room air temperature and the possibility of energy savings. Finally, the humidity sensor can be located with the current thermostat in that there are small differences in absolute humidity in vertical distribution.