• Journal of Power Electronics
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• v.10 no.3
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• pp.293-299
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• 2010

In this paper, a single-phase PFC (Power Factor Correction) dual boost converter based on input voltage estimation is studied for DC inverter air conditioner. It is focused on improving input power factor and power quality to satisfy the recent harmonic current regulation standards. Furthermore the input voltage estimation is introduced for price competitive products. A low cost and reasonable control system is implemented using a specified high-speed 32-bit microprocessor. Their effectiveness are verified through theoretical analysis and experiments.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.113-118
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• 2007

As the economic living standards are higher, the demands for more comfortable living space are also larger. In the response of this requirements, studies for improving indoor air environment have been conducted. In case of newly-built apartment buildings, the standard for the minimum ventilation to improve their indoor air quality was made. This study analysed the experimental results from the mock-up test of the hybrid ventilation system which is composed of natural and mechanical ventilation.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.126-131
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• 2007

This study aims to present the fundamental strategies for improving the Indoor Air Quality(IAQ) in newly-constructed apartment buildings. To investigate the concentration of indoor air pollutants such as HCHO and VOCs and the field measurement were conducted. According to the field measurement of 60 new houses in spring season, the concentration of HCHO in about 20% were higher the IAQ standards.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.6
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• pp.788-793
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• 2017

This military aircraft requires the compatibility evaluation of armed installations in accordance with guidelines and standards. In order to ensure the influence of gas-air mixtures caused by gunfire of the supersonic aircraft, CFD analysis of internal and external flows was performed and the results carried out and discussed. The low velocity vortex was formed due to the shape of the Gun Port, after firing the gas-air mixture was evacuated to the outside flow, where it moved to the front of the aircraft and soon merged with the aircraft flow field.

• Environmental and Resource Economics Review
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• v.29 no.2
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• pp.113-144
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• 2020

Throughout various data sources, it is widely observed that air quality in South Korea has become improved. Koreans, however, insist that their health status and economic burden due to worsened air quality get degenerated. This study aims to explain the mismatch between perception and measured data, air pollution-led medical expenses, and consumption behaviors in the economics perspectives. First, we demonstrated data-driven evidence of mismatch in the perceived severity of air pollution and its enhancement in measured data. Second, using the health demand model, we theoretically derived and empirically showed a co-rising relation between air pollution severity and medical expenses. Last, we analyzed that the perception led to increased defensive expenditures in consumption. This result implies the possibility of overestimation in air pollution impacts on socioeconomic losses and its possible reverse interpretation from increased social benefit after improved air quality. Our results recommend policy consideration to strengthen air quality standards, to support socially vulnerable groups regarding defensive expenditures, and to improve the accessibility and credibility of air pollution information.

• Analytical Science and Technology
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• v.26 no.3
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• pp.165-173
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• 2013

To establishment of PT Program for Indoor air quality field that manufacture of confidential development PTMs (proficiency testing materials) and examined of proficiency testing evaluation included sampling process whether or not that is valid. Confirmation of homogeneity and stability of PTMs prepared. PTMs were confirmed to be homogeneous enough to be used as proficiency testing materials since withinbottle homogeneities of the RMs were lower than 0.3 times of targeted standard deviation of proficiency testing. The result of this study showed that the Robust RSD of proficiency testing for VOCs (volatile organic compounds) appeared 23~43% in concentration of 50~320 ${\mu}g/m^3$ for Method A(Distribution by adsorption in Tenax-tube of VOCs), but less 13~42% in concentration of 200~1200 ${\mu}g/m^3$, 16~31% in concentration of 100~450 ${\mu}g/m^3$ for Method B (distribution by VOCs of gas phase in 10L Tedalr bag), C (directly sampling of cylinder with high pressure) respectively. The result of this study showed that method C with sampling is most adequate to the proficiency testing for VOCs in indoor air.

• Journal of Environmental Impact Assessment
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• v.31 no.6
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• pp.378-387
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• 2022

Since air pollution has become a global issue to be managed, the Republic of Korea (ROC) is protecting air quality by predicting the air condition before a construction project starts through EnvironmentalImpact Assessment (EIA) and measuring the air condition afterwards the construction project ends through Post-environmental Impact Assessment (PEIA). The aim of this study consists on verifying the predicted and measured concentration data and analyzing their consistency in order to deduce improvement directions. Linear EIA projects which the investigation during operation period have been concluded between years 2017 and 2019 were used. As a result, the following improvement directions were suggested: reduction of EIA air quality standards, strengthen the management of projects with construction duration longer than 5 years, incorporation of first or second quarter (winter or spring) into the investigation period, consideration of construction equipment or conditions for better prediction. The strength of this study is that we arranged and utilized EIA predicted and PEIA measured data to understand the present EIA procedure and made meaningful suggestions through the consistency analysis contributing to air quality maintenance and investigation methodology enhancement.

• Journal of Preventive Medicine and Public Health
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• v.36 no.1
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• pp.47-53
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• 2003

Objectives : I used a case-crossover design to investigate the association between air pollution, and hospital admissions for asthmatic children under the age of 15 years in Seoul, Korea Methods : I estimated the changes in the levels of hospitalization risk from theinterquartile (IQR) increase in each pollutant concentrations, using conditional logistic regression analyses, with controls for weather information. Results : Using bidirectional control sampling, the results from a conditional logistic regression model, with controls for weather conditions, showed the estimated relative risk of hospitalization for asthma among children to be 1.04 (95% confidence interval (CI), 1.01-1.08) for particulate matter with an aerodynamic diameter less than or equal to 10m (IQR=40.4ug/m3); 1.05 (95% CI, 1.00- 1.09) for nitrogen dioxide (IQR=14.6ppb): 1.02 (95% CI,0.97-1.06) for sulfur dioxide (IQR=4.4ppb): 1.03 (95% CI, 0.99-1.08) for ozone (IQR=21.7ppb): and 1.03 (95% CI, 0.99-1.08) for carbon monoxide f10R=1.0ppm). Conclusions : This empirical analysis indicates the bidirectional control sampling methods, by design, would successfully control the confounding factors due to the long-term time trends of air pollution. These findings also support the hypothesis that air pollution at levels below the current ambient air quality standards of Korea is harmful to sensitive subjects, such as asthmatic children.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.4
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• pp.369-377
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• 2013

The trends of the criteria air pollutants' concentrations over Seoul are reviewed, relative contributions of major sources are discussd, and directions for future air quality management are suggested. It was shown that the yearly average concentrations of the criteria air pollutants except nitrogen dioxide and ozone have decreased significantly over the last three decades. Though the concentration of nitrogen dioxide has not decreased, the concentration of $NO_x$ has decreased significantly. The major reason for the reduction of the criteria air pollutants has been strict government regulations such as establishment of strict emission standards and switch to cleaner fuels. However, it is not clear the major reason (s) for the reduction of the $PM_{10}$ concentration. It is suggested that to further reduce the concentrations of secondary air pollutants such as ozone and $PM_{2.5}$, understanding the major chemical pathways for them is essential. In addition, influence from outside Seoul should be quantified and effectively controlled.

• Journal of the Korean Professional Engineers Association
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• v.15 no.1
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• pp.46-50
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• 1982

Following rapid industrial development and urbanization in Korea, there is a need for the Government to implement effective control of pollution and to undertake specific schemes in areas where pollution of the environment is severe. In response to this need, Government of Korea prepare Han River Basin Environmental Master Plan Project for water, air, solid waste to cover environmental protection of the Han River Basin. The Project area is approximately 27,000 sq. Km extending over Seoul, Kyunggi, Kwangwon, Chungbuk Province. The total population of Master Plan Project area is approximately 11.6 million, or one-third of the total population of Korea. There are about 8,000 industries, including those located in 16 industrial complexes, in the project area. The scope of work and terms of reference are the following: (1) A Summary of existing land use and forecasts for changes in land use by the year 2,000. (2) Emission inventories for air, waste water, and solid wastes. (3) Forecasts of future population growth patterns and pollution loadings. (4) Identification of specific projects needs to reduce pollution levels and satisfy the environmental quality standards. (5) A Program of enforcement to include (i) self monitoring, and (ii) governmental inspections and surveillance. (6) A program for quality improvement and quality assurance of environmental measurements. (7) Reports summarizing all data collected analyzed during the study. (8) Conceptual design and feasibility studies, including cost estimates, for needed pollution control projects. (9) A financial plan for future detailed design and construction of public facilities, for financial incentives to industry, and for user charges for industrial use of public treatment of disposal works.