• 설비공학논문집
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• 제22권1호
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• pp.26-32
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• 2010

This paper is suggesting a new technology for refrigerant amount detection of a system air-conditioner installed under various installation conditions. System air-conditioner was introduced to domestic market first in 2000. It consists of one or a series of outdoor units and a number of indoor units connected with single pipe line to the outdoor unit. The system can vary the capacity from 2.0 kW to 186 kW. For the system Installed under long and high-elevated condition, about 100 kg of refrigerant is charged in the whole system. In this paper, the new technology RAD (Refrigerant Amount Detection) with edge technology of refrigerant cycle control and measurement of a system air conditioner was developed and investigated for its application for the various installation conditions.

• 대한기계학회논문집B
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• 제34권7호
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• pp.697-702
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• 2010

전열교환 엘리먼트는 열회수형 환기유닛의 핵심부품으로, 외기와 실내공기의 열 및 수분교환이 이루어진다. 본 연구에서는 현재 국내에서 사용되고 있는 전열교환 엘리먼트에 대하여 외기의 온 습도 변화가 전열교환 엘리먼트의 성능에 미치는 영향을 실험적으로 연구하였다. 전열교환 엘리먼트를 통과 하는 공기 유량, 입 출구의 건 습구 온도를 정밀하게 측정할 수 있는 실험장치를 특별히 제작하였고, 항온항습실내에서 외기의 상대습도 또는 절대습도를 변화시키며 실험을 수행하였다. 실험결과는 현열전달 유용도과 잠열전달 유용도으로 평가되는데 잠열 전달 유용도는 외기의 상대습도의 증가에 따라 증가하였으나 절대습도의 변화에는 거의 무관하게 냐타났다. 한편 현열 교환 유용도는 외기의 온도 및 습도 변화에 무관하게 일정하였다.

• 설비공학논문집
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• 제14권11호
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• pp.890-896
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• 2002

Purpose of this study is to clarify the evaluation of thermal comfort based on temperature differences between outdoor and indoor thermal conditions in summer. The experiments were performed to evaluate temperature difference between indoor and outdoor thermal conditions (29, 31, $33^{\circ}$) by physiological and psychological responses of human. According to physiological responses, TSV (thermal sensation vote) and CSV (comfort sensation vote) and psychological responses, ECG (electrocardiogram), MST (mean skin temperature) of human, it was clear that the optimum temperature difference is about $5^{\circ})\;and\;7^{\circ}$).

• 설비공학논문집
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• 제20권2호
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• pp.121-127
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• 2008

This paper investigates the effects of outdoor pressure fluctuations on natural ventilation through an opening on a building envelope. The ventilation airflow rate depends on the magnitude and the period of the pressure fluctuations, the size of the opening relative to the space volume, and the resistance characteristics of the opening. Non-dimensional parameters have been derived, which determine indoor pressure responses due to outdoor pressure fluctuations. The flow regions are categorized into (1) synchronized region, (2) opening resistance region, and (3) transition region depending on the non-dimensional parameter derived. Pressure fluctuations and flow characteristics are investigated numerically using the 4th order Runge-Kutta method.

• 설비공학논문집
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• 제13권6호
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• pp.532-540
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• 2001

The objectives of this study are to analyze the control variables according to condensation occurrence, to find the range in floor surface temperature and frequency of condensation, and to evaluate the control methods through simulations when the radiant heating system is used for cooling. Through the simulation analysis the control methods such as on/off control, variable flow control and outdoor reset with indoor temperature feedback control are evaluated and compared. The results show that the lowest floor surface temperature is around $23^{\circ}C$, the surface condensation can be prevented by controlling indoor humidity within 20g/kg(DA0, and that outdoor reset with indoor temperature feedback control is more appropriate than on/off control and variable flow control with regard to prevention of the condensation and thermal comfort.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.244-249
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• 2008

In this study, the characteristics of flow in outdoor unit were numerically analyzed. Parametric studies were performed to compare the effect of bell mouth height, fan height and fan width concerned with flow rate. The result indicated that the flow rate was dependent on the bell mouth height, while it was negligibly affected by the fan height and fan width. The fan width was found to affect the velocity distribution at heat exchanger face.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.427-432
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• 2005

This study developed a program for detecting charged refrigerant amount in system air-conditioner. System air-conditioner is an air-conditioning system with multiple indoor units. Due to the complexity of the system, it is more difficult to detect the refrigerant amount charged in system air-conditioner than in a general single air-conditioner. Experiments were performed for 6 HP outdoor units with 3 indoor units in a psychrometric calorimeter. The experimental amount of charged refrigerant were ranged from 60% to 140% with 10% increasement. Fuzzy algorithm were emploeed for detecting the charged refrigerant amount in a system air-conditioner. The experimental data were used for curve fitting for general ranges for indoor and outdoor temperature conditions. membership function were determined for whole ranges of experimentally measured data and rulebase were defined for each amount of refrigerant charge. Developed program successfully predicted the measured data within 10% resolution range.

• 한국환경보건학회지
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• 제26권4호
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• pp.134-140
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• 2000

The increase in traffic is a worldwide phenomenon. In Korea, it has been increased by 20% per annual in recent 1990’s and approximately 10 millions cars had been registered until 1997. This traffic could easily affect and contribute the local outdoor air quality(QAQ) concerned. The QAQ in highway in one of the examples and the subject in this study. The seoul tollgate located at the north-end of Keypngbu Highway was selected for the study. In case of highway tollgate, the local air pollution could be directly affected by the traffic to approach, wait and start the tollgate. Nitrogen dioxide (NO$_2$) concentration exceeded the EAQS(Environmental Air Quality Standards), but overall indoor air quality was a little better than the outdoor air quality. The measured TSP concentration was much higher than that of the EAQS. To apply a management to a air quality problem of Seoul tollgate, it was predicted air quality with traffic volume and weather condition. It was calculated NO$_2$ emission with traffic volume and predicted in and out of booth by CALINE3 at the Seoul tollgate. To make a comparison between measured and predicted concentration, the prediction was good. It was shown that NO$_2$ concentration was high in the morning at the from Seoul direction and in the evening at the to Seoul direction. it was thought that NO$_2$ concentration variation was reflected according to the traffic volume.

• 한국환경보건학회지
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• 제37권5호
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• pp.387-395
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• 2011

Purpose: This study measured the burden of disease in Korea related to outdoor air pollution using disability-adjusted life year (DALY). Materials and Methods: As a risk factor of outdoor air pollution, particulate matter with a diameter less than 10 ${\mu}m$($PM_{10}$) was used. First, $PM_{10}$-related diseases and their relative risk (RR) were selected by means of a literature review. Second, population attributable fractions were computed by using formulae including RR and population exposure to $PM_{10}$. Third, DALYs of $PM_{10}$-related diseases in Korea were estimated. Finally, the attributable burden of disease due to $PM_{10}$ was measured as the sum of the products that multiplied the DALYs of $PM_{10}$-related diseases by their population attributable fractions. Results: The disease burden of PM10 was 6.9 DALY per 1,000 persons in 2007. The attributable burden of $PM_{10}$ was 2.68 for lung cancer, 2.41 for COPD, 0.62 for ischemic heart disease, 0.61 for pneumonia, 0.55 for asthma, and 0.03 for preterm. Conclusions: This study showed the environmental burden of disease of $PM_{10}$ and burden of $PM_{10}$-related disease through objective data. It also suggested that active efforts are needed to continuously measure and reduce the burden of environmental diseases in Korea.

• Advances in environmental research
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• 제2권1호
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• pp.61-80
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• 2013

Quantification of viable forms of microbial community (bacteria and fungi) using culture-dependent methods was done in order to characterize the indoor air quality (IAQ). Role of those factors, which may influence the concentration of viable counts of bacteria and fungi, like ventilation, occupancy, outdoor concentration and environmental parameters (temperature and relative humidity) were also determined. Volumetric-infiltration sampling technique was employed to collect air samples both inside and outside the schools. As regard of measurements of airborne viable culturable microflora of schools during one academic year, the level of TVMCs in school buildings was ranged between 803-5368 cfu/$m^3$. Viable counts of bacteria (VBCs) were constituted 63.7% of the mean total viable microbial counts where as viable counts of fungi (VFCs) formed 36.3% of the total. Mean a total viable microbial count (TVMCs) in three schools was 2491 cfu/$m^3$. Outdoor level of TVMCs was varied from 736-5855 cfu/$m^3$. Maximum and minimum VBCs were 3678-286 cfu/m3 respectively. Culturable fungal counts were ranged from 268-2089 cfu/$m^3$ in three schools. Significant positive correlation (p < 0.01) was indicated that indoor concentration of viable community reliant upon outdoor concentration. Temperature seemed to have a large effect (p < 0.05, p < 0.01) on the concentration of viable culturable microbial community rather than relative humidity. Consistent with the analysis and findings, the concentration of viable cultural counts of bacteria and fungi found indoors, were of several orders of magnitude, depending upon the potential of local, spatial and temporal factors, IO ratio appeared as a crucial indicator to identify the source of microbial contaminants.