• Journal of the Korean Solar Energy Society
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• v.28 no.3
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• pp.27-34
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• 2008

A series of outdoor tests were conducted on a fiber optic solar concentrator system for its performance on daylighting. The system is comprised of four main components - a parabolic dish reflector, a convex mirror, a homogenizer tube and an optical fiber cable. Results show that the system could be successfully applied for indoor lighting if some improvements are made for light transmiting (optical) cables. A maximum concentration ratio of 90 was observed delivering the illuminance of 4,800 lux at a distance of 1.2m from the diffuser for the outdoor illuminance of 102,100 lux.

• Journal of Environmental Health Sciences
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• v.28 no.1
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• pp.85-92
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• 2002

A measurement of indoor microorganism using Reuter Centrifugal Air Sampler(RCS) was undertaken during October 1991 - February 1999 and 6-Stage Cascade Air Sampler was undertaken during May 2001 - June 2001 in Seoul. Sites including book store, department store, theater, subway station, underground shopping center, hospital, office building, sports facility, and eduationa institutio were chosen to measure indoor microorganism. The results were as follows: 1. The average of total microorganism collected on the agar strip GK-A media were, in the order, subway station, hospital, underground shopping center, department store, book store, theater, sports facility, educational institution, office building in sites. The highest concentration of 711cfu/m$^3$ was found in the subway station and the lowest concentration of 44cfu/m$^3$ was found in office building. 2. The average of staphylococci collected on the agar strip GK-S media, in the order, were subway station, underground shopping center, hospital and department store, department store, theater, office building, sports facility and educational institution in sites. The highest concentration of 502cfu/m$^3$ was found in the subway station and the lowest concentration of 14cfu/m$^3$ was found in sports facility and educational institution. 3. The average of fungus collected on the agar strip GK-HS media, in the order, were underground hospital, shopping center, theater, subway station, department store, book store, sports facility, educational institution, and office building in sites. The highest concentration of 252cfu/m$^3$ was found in the hospital and the lowest concentration of 32cfu/m$^3$ was found in office building. 4. Ratio of Indoor/Outdoor, determined by site was 1.12-2.38 in total count, 1.00-2.35 in staphylococci, and 0.99-1.34 in fungus. 5. The positive results of test were 12-24% in indoor and 9-43% in outdoor. 6. By gram staining gram positive cocci were 59.9%, gram positive bacill 24.4%, gram negative bacilli 10.4%, and gram negative cocci 0.5%.

• Journal of Environmental Health Sciences
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• v.45 no.2
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• pp.186-191
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• 2019

Objectives: Subway is one of the most common transportation modes in Seoul, Korea. The objectives of this study were to determine characteristics of in-cabin $PM_{2.5}$ concentration in Seoul Metro Line Number 2 and to identify factors of the $PM_{2.5}$ concentration. Methods: In-cabin $PM_{2.5}$ concentrations in Seoul Metro Line Number 2 were measured using real-time monitors and the factors affecting $PM_{2.5}$ concentration in cabin were observed. Linear regression analysis of in-cabin $PM_{2.5}$ concentration and indoor/outdoor (I/O) ratio were performed. Results: In-cabin $PM_{2.5}$ concentration was associated with the in-cabin $PM_{2.5}$ concentration in previous station. In-cabin $PM_{2.5}$ concentration was correlated with ambient $PM_{2.5}$ concentration and associated with underground station with control of the in-cabin $PM_{2.5}$ concentration in previous station. I/O ratio increased as the number of passengers increased and when passing through the underground station with control of I/O ratio in previous station. Conclusion: In-cabin $PM_{2.5}$ concentration was affected by ambient $PM_{2.5}$ concentration. Therefore, management of in-cabin $PM_{2.5}$ concentrations should be based on outdoor air quality.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2456-2467
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• 2018

Wireless multimedia sensor networks (WMSNs) require real-time quality-of-service (QoS) guarantees to be provided by the network. The end-to-end delay is very critical metric for QoS guarantees in WMSNs. In WMSNs, due to the transmission errors incurred over wireless channels, it is difficult to obtain reliable delivery of data in conjunction with low end-to-end delay. In order to improve the end-to-end delay performance, the system has to drop few packets during network congestion. In this article, our proposal is based on optimization of end-to end delay for WMSNs. We optimize end-to-end delay constraint by assuming that each packet is allowed fixed number of retransmissions. To optimize the end-to-end delay, first, we compute the performance measures of the system, such as end-to-end delay and reliability for different network topologies (e.g., linear topology, tree topology) and against different choices of system parameters (e.g., data rate, number of nodes, number of retransmissions). Second, we study the impact of the end-to-end delay and packet delivery ratio on indoor and outdoor environments in WMSNs. All scenarios are simulated with multiple run-times by using network simulator-2 (NS-2) and results are evaluated and discussed.

• Journal of Mushroom
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• v.14 no.3
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• pp.119-126
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• 2016

Five empirical farmhouses were selected to reduce the high temperature damage in oak mushroom cultivation using bed-logs. The cultivation facilities were categorized as follows: those having two blackout curtains or one blackout curtain and outdoor oak mushroom cultivation. The inequality of the indoor condition, oak mushroom hyphae rampant ratio, and fruit body production in each test condition was evaluated. $3^{\circ}C$ was lower in indoor temperature of cultivation facility having two blackout curtains than one blackout curtain. Specifically, the indoor air humidity average of cultivation facilities having one or two blackout curtains was 10% lower than that of outdoor oak mushroom cultivation. This condition is not ideal for oak mushroom cultivation as continuous indoor humidity control is essential for producing good fruit bodies. The Inoculated bed-log surface and oak mushroom hyphae rampant ratio of bed-logs cultivated with two blackout curtains was superior to other tested conditions. The mushroom production ratio observed in facilities with two blackout curtains was 117-204% higher than those cultivated in facilities with only one blackout curtain. Furthermore, the mushroom production ratio increased in based on these findings, we recommended five cultivation facility models to reduce high temperature damage in oak mushroom cultivation using bed-logs.

• Journal of Environmental Health Sciences
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• v.41 no.6
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• pp.369-379
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• 2015

Objectives: The lack of reliable information on environmental pollution and health impacts related to asbestos contamination from abandoned mines has drawn attention to the need for a community health study. This study was performed to evaluate asbestos-related health symptoms among residents near abandoned asbestos mines located in the Chungcheong Provinces. In addition, exposure assessment for asbestos is needed although the exposure to asbestos was in the past. Methods: Past exposure to asbestos among inhabitants near abandoned asbestos mines was estimated by using surface sampling of deposited dust in indoor and outdoor residences. A total of 54 participants were divided into two groups with (34 cases) and without (20 controls) diseases related to asbestos. Surface sampling of deposited dust was carried out in indoor and outdoor residences by collecting 105 samples. Deposited dust for sampling was analyzed by polarization microscope (PLM) and scanning electron microscope?energy dispersive x-ray spectrometer (SEM-EDX) to detect asbestos. Subsequently, the elements of the deposited dust with asbestos were analyzed by SEM-EDX to assess the contribution of sources such as abandoned mines, slate and soil. Results: Among the 105 samples, asbestos was detected by PLM in 29 (27.6%) sampling points, and detected by SEM in 56 (48.6%) sampling points. Asbestos in indoor residences was detected by PLM in four sampling points, and by SEM in 12 sampling points. Asbestos detection in indoor residences may be due to ventilation between indoors and outdoors, and indicates long-term exposure. The asbestos detection rate for outdoor residences in the case group was higher than that in the control group. This can be explained as the case group having had higher exposure to asbestos, and there has been continuous exposure to asbestos in the control group as well as the case group. Conclusion: Past residential asbestos exposure may be associated with asbestosis among local residents near abandoned asbestos mines. Odds ratios were calculated for asbestos detection in outdoor residence by logistic regression analysis. Odds ratio between asbestos detection and asbestosis pulmonum was 3.36 (95% CI 0.90-12.53) (p=0.072), adjusting for age, sex, smoking status and work history with multi-variable logistic regression by PLM analysis method.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1649-1651
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• 2008

A novel configured S-IPS LCD has been developed introducing a new compensation film with an anti-reflective layer. This new technology provides wide viewing characteristics as well as excellent visibility under bright indoor lighting or natural lighting.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.2
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• pp.216-232
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• 2016

In present, the Seoul City is undergoing traffic congestion problems caused by rapid urbanization and population growth. Thus the City government has reorganized the mass transportation system since 2004 and the subway has become a very important means for public transit. Since the subway system is typically a closed environment, the indoor air quality issues have often raised by the public. Especially since a huge amount of PM (particulate matter) is emitted from ground tunnels passing through the subway train, it is now necessary to assess the characteristics and behaviors of fine PM inside the tunnel. In this study, the concentration patterns of $PM_1$, $PM_{2.5}$, and $PM_{10}$ in the Seoul subway line-2 were analyzed by real-time measurement during winter (Jan 13, 2015) and summer (Aug 7, 2015). The line-2 consisting of 51 stations is the most busy circular line in Seoul having the railway of 60.2 km length. The the one-day average $PM_{10}$ concentrations were $148{\mu}g/m^3$ in winter and $66.3{\mu}g/m^3$ in summer and $PM_{2.5}$ concentrations were $118{\mu}g/m^3$ and $58.5{\mu}g/m^3$, respectively. The $PM_{2.5}/PM_{10}$ ratio in the underground tunnel was lower than the outdoor ratio and also the ratio in summer is higher than in winter. Further the study examined structural types of underground subsections to explain the patterns of elevated PM concentrations in the line-2. The subsections showing high PM concentration have longer track, shorter curvature radius, and farther from the outdoor stations. We also estimated the outdoor PM concentrations near each station by a spatial statistical analysis using the $PM_{10}$ data obtained from the 40 Seoul Monitoring Sites, and further we calculated $PM_{2.5}/PM_{10}$ and $PM_1/PM_{10}$ mass ratios near the outdoor subway stations by using our observed outdoor $PM_1$, $PM_{2.5}$, and $PM_{10}$ data. Finally, we could develop pollution maps for outdoor $PM_1$ and $PM_{2.5}$ near the line-2 by using the kriging method in spatial analysis. This methodology may help to utilize existing $PM_{10}$ database when managing and control fine particle problems in Korea.

• Journal of Energy Engineering
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• v.11 no.2
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• pp.130-135
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• 2002

Bypass air conditioning systems are divided into three types; outdoor air bypass, mixed air bypass and return air bypass system. Among bypass air conditioning systems, a return air bypass system is more effective than other two systems because it doesn't induce unconditioned outdoor air into conditioned room. The numerical study on the bypass air conditioning system shows this system can maintain indoor RH(Relative Humidity) less than a conventional CAV (Constant Air Volume) air conditioning system by adjusting face and bypass dampers at part load. A simulator was built to compare results of a numerical experiment and those of a simulator experiment. The results of the simulator experiment was nearly same as those of the numerical experiment; when a design sensible load (the ratio of sensible load to total sensible load) was 70 percent (at this time, RSHF=0.7), indoor relative humidity (in case of both numerical experiments and simulator experiments) was maintained below 60% specified by ASHRAE STANDARD 62-1999. The bypass air conditioning system is expected to be applied to many buildings where the Percentage of latent loads or air change tate is high.

• KIEAE Journal
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• v.15 no.2
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• pp.123-131
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• 2015

Purpose : Improvement of indoor thermal comfort and reduction of the energy consumption in building can be obtained by applying a double skin facade system. In order to achieve effectively this purpose, design team would have to perform easy and appropriate performance analysis for making better design decision during the design process. Method : This paper focus on the natural ventilation performance of a multi-story type double skin facade with main causes which are pressure difference according to the wind and temperature difference between indoor and outdoor (Buoyancy Effect). Using this main causes, the natural ventilation ratio of wind effect-to-buoyancy effect in cavity of multi-story type double skin facade were analyzed through the performance analysis results of CFD (Computational Fluid Dynamics) simulation. Result : When the wind velocity was 2m/s, the ventilation rate in the cavity was highest. If wind velocity was slower than 2m/s wind velocity, buoyancy effect has more influence on the ventilation rate in the cavity, and if wind velocity was faster than 2m/s wind velocity, wind effect has more influence on the ventilation rate in the cavity.