• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.214-217
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• 2003

The connectorless power supply system on that multi-contact causes confidence when the wiring reconstructed in the rear. As you see above, contact points between sets and indoor space cause inferior function of audio frequency so it needs to be eliminated. This paper explains the structure of connectorless power supply to supply the system with power crossing the air gap in the part of inductively in the connectorless power supply of both magnetic and electrical model. To get maximum output of electrical load, compensating capacitor compensates to show inter-inductance, lequeage-inductance reducing the track-inductance and access the conditions for resonance. At that time it accesses the maximum electric power. The small change of the value of compensating capacitor causes the changes of maximum electric power. Here the power electronics technology is used not only in the industrial machinery but also in the home appliances so the switching power supply is used to actualize the miniaturization, lightweight, and high efficiency. Generally the condenser input methods are widely used in the rectification circuit of switching power supply, but condenser input method generate great quantity of high frequency components because with this method the current flows in the power input filtering condenser only around value of peak of ac input voltage. To solve these problems, installation of power factor improve circuit on the front of filtering capacitence was considered. Several methods were suggested regarding, but the active filter method which makes smalliging and highly power factor possible are the produce main stream. IC for power factor improvement can be utilized by CMOS process proposing low power consumption. When the high power factor is considered seriously in the power factor improvement circuit, active filter method is selected. In the active filter method, the boost converter is used. Regarding this ·the boost converter is needed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.3
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• pp.210-215
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• 2002

In this study, the computer program called Multi_Cycle, which simulates the steady-state performance (coefficient of performance, capacity, power consumption and etc.) of multi- airconditioning systems using R410A, was developed. In order to validate the simulation program, a series of case studies were carried out. The Multi_Cycle consists of several subroutines for simulating indoor units. outdoor unit, compressor, and expansion devices. and for estimating the thermodynamic and transport properties of the refrigerants and moist air. It would appear to be advantageous to use the Multi_Cycle for a performance analysis when considering various kinds of refrigerants and the complex operating conditions of each unit making up the multi-airconditioner cycle. Moreover, the Multi_Cycle would seem to be useful tool in optimizing a multi-airconditioning system and establishing economical and efficient operating conditions in the multi-airconditioner cycle. In the present study, the Multi_Cycle was programmed with Digital Visual Fortran for the main simulation code and Visual Basic for- the graphic user interface.

• Journal of Mushroom
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• v.18 no.1
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• pp.72-78
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• 2020

During the monitoring of fungal pests in 2016 and 2017, Acrodontium crateriforme, Naganishia friedmannii, Pestalotiopsis trachicarpicola, Penicillium wollemiicola, and Trichoderma thailandicum were isolated from indoor air, mushroom flies (Phytosciara flavipes), and media materials in the cultivation houses of oak wood mushroom (Lentinula edodes) located in Seocheon, Jangheung, Buyeo, and Yeoju, Korea. These fungal species were identified based on their morphological characteristics after their growth on PDA and subsequent molecular analyses of the 26S rDNA, 28S rDNA, β-tubulin gene, and translation elongation factor 1-α gene using PCR amplification and nucleotide sequencing were performed. The results showed that these fungi were previously undocumented in Korea. This study reports descriptions of their taxonomical and known properties.

• Fire Science and Engineering
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• v.28 no.6
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• pp.108-113
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• 2014

The combined process of Sliding Arc Plasma and corona dielectric barrier discharge process (CDBD) was used to efficiently improve harmful substance, which convert into OH radicals which have strong oxidation potential, and so have deodorization and sterilizing effects, by generating specific radicals and anion and then reacting with the moisture contained in harmful substance. As a result of experiment, even if the size of SAP reactor is reduced from 80 A to 50 A, there is no much change and therefore it is judged the size of reactor may be minimized. And it was confirmed that after the anion and ozone generated from CDBD rector react with harmful substance, a anion was reduced from 510,000 ppb to 470 ppb and ozone from 98 ppb to 22 ppb. It was also judged the stability and durability of plasma producer are excellent. Accordingly, it is considered the harmful substances which exist in indoor air quality will be efficiently improved and removed by using further plasma combined process through this study.

• Fire Science and Engineering
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• v.29 no.6
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• pp.98-108
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• 2015

An integrated command system is critical for the safety of firefighters and effective work in the headquarters of a special disaster areas such as natural disaster or large man-made hazard. The integrated command system requires environmental information such as temperature, humidity, and $CO_2$ levels, as well as personal physical information such as pulse and air respirator levels. An Analog to Digital Converter (ADC) chip converts sensed information into digital signals, and a Micro Controller Unit (MCU) transmits the digital signals to a transmission board using serial communication through a Serial Peripheral Interface (SPI). The digital signals are saved in a transmission board and transmitted to the integrated command system by a Radio Frequency (RF) unit. The location of fire-fighters in a building are determined using a gyro sensor and an inertial sensor. The collected information is applied to the integrated command system for firefighter safety and to ensure that they can effectively carry out their duties. Tthis study theoretically and experimentally investigated the technologies of RF transmission, indoor position, and an integrated command system that supports decision making using the transmitted information.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.3
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• pp.300-309
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• 2014

Objectives: The objective of this study is to evaluate microbial exposure hazards in the metal-working fluids(MWF) handling industry. Methods: Air quality parameters(airborne bacteria, fungi, endotoxin and oil mist) and bulk MWF in storage tanks were evaluated at 54 points at nine sites in South Korea. Results: The geometric means(GM) of culturable airborne bacteria, fungi, endotoxin and oil mist concentration were $133CFU/m^3$(n=376, range $7{\sim}6,510CFU/m^3$), $159CFU/m^3$(n=381, range $7{\sim}8,469CFU/m^3$), $8.06EU/m^3$(n=103, range $0.34{\sim}280.4EU/m^3$) and $0.20mg/m^3$(n=104, range $0.01{\sim}2.87mg/m^3$), respectively. The ratio of indoor to outdoor concentration was 2.7 for bacteria, 6.1 for endotoxin, and 4.8 for oil mist. Even though average airborne bacteria concentration did not exceed recommended exposure limits($1,000CFU/m^3$), MWF in the storage tanks was highly contaminated with bacteria(arithmetic mean $2.1{\times}10^6CFU/ml$) and exceeded recommended bacteria limits($10^5CFU/ml$). Conclusions: It is necessary for MWF handling workplaces to conduct periodical biohazard inspection of MWF storage tanks. Additionally, further research may be necessary to establish biological occupational exposure limits.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.1
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• pp.46-51
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• 2014

Objectives: The principal aim of this study was to compare the concentrations of gaseous pollutants emitted in enclosed pig buildings between different rates of general ventilation and determine the variations in the patterns of gaseous pollutants as affected by ventilation rate. Materials and Methods: The experiment was performed in the growing/finishing room($20.0m{\times}12.0m{\times}3.0m$) of a pig confinement building located on the experimental farm of Seoul National University. The conditions of the general ventilation rate for three treatments were 30%($4.12m^3s^{-1}$), 50%($6.87m^3s^{-1}$) and 70%($9.61m^3s^{-1}$). The data presented in the study were collected overa total of 45 days, 15 days for each of the three treatments from March to May 2011. A total of six air samplings were taken at 1.5m above the floor of the pig building. The environmental agents measured in the pig building were ammonia, hydrogen sulfide and odor concentration index for gaseous pollutants with temperature and hydrogen sulfide for thermal factors. Results: There were significant differences in the ammonia and odor concentration index in the pig building among the three general ventilation rate conditions(p<0.05), whereas hydrogen sulfide did not show a significant difference among three conditions of general ventilation rate(p>0.05). As the general ventilation rate applied to the pig building increases, it appears that all the indoor environmental agents measured in this study simultaneously decrease. Conclusions: The gaseous pollutants significantly affected by the general ventilation rate in pig building were ammonia and odor concentration index(p<0.05). However, it was found that hydrogen sulfide and thermal factors, temperature and relative humidity were not influenced significantly by variation in the general ventilation rate.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.28 no.2
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• pp.200-210
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• 2018

Objectives: The purpose of this study is to assess the exposure to ozone and total volatile organic compounds(TVOCs) generated during welding work at a shipyard and recommend respiratory protective equipment(RPE) adequate against these hazards. Method: Ozone was collected for about 30 minutes at two-minutes intervals using a direct reading instrument, specifically an ozone analyzer(Serinus 10, Ecotech, Australia). TVOCs were collected for about 30 minutes at three-minute intervals using a portable GC (Alpha 115, Synspec BV, the Netherlands), and were determined simultaneously by area sampling at the welding plume closest to the welder's breathing zone. The total measurements were 162 for ozone($CO_2$ welding 47, TIG 60, stick 55), and 136 for TVOCs($CO_2$ 65, TIG 50, stick 21). Based on these measurements, a literature survey was conducted to assess the adequacy of RPE. Results: Relative to Korean OEL, measurements above STEL 0.2 ppm were 23.4% for $CO_2$, 63.3% for TIG and 14.5% for stick welding. There were significant differences(p=<0.0001) among welding types. Compared with ACGIH peak exposure of 0.4 ppm for ozone, which is not applied in Korea, $CO_2$ welding exceeded it by 10.6%, TIG by 40.0% and stick by 7.3%. Although it was not feasible to compare them directly since there are no Korean OEL, TVOCs had very high levels similar to the concentrations before moving into a new apartment and about 10-20 times the indoor air quality recommendations for some individual measurements. Conclusions: As ozone removal RPE has been recommended in welding environments for a long time(Lunau, 1967), this fact was demonstrated based on the results of the on-site work environment measurements(ozone and TVOCs). In conclusion, for all welding at a shipyard, gas/vapor and particulate combination RPE are recommended. If this is not possible, it should at least be present for TIG welding.

• Journal of the Korea Furniture Society
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• v.26 no.2
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• pp.122-129
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• 2015

In previous study, VOC emission characteristics of coating materials for wood finishing were conducted and results showed that eco-friendly products has about 15~46% lower TVOC emission than typical products. In this study, lower TVOC emitted coating materials were applied on pine and then changes of VOC emission characteristics from pine with treatments were determined. Non-treated pine emitted $604.7{\mu}g/m^2h$ of TVOC that contained 66% of NVOC ($399.7{\mu}g/m^2h$). However, $V_2$ finished pine showed no NVOC emission rather than AVOC emission that consisted of Toluene, Ethylbenzene, m,p-Xylene, o-Xylene, 1,2,4- Trimethylbenzene. All coating materials inhibited ${\alpha}$-Pinene emission which originally from pine, but waterborne stain ($W_1$ and $W_3$) showed lower disruption of that emission. Moreover, $W_3$/wood showed higher NVOC emission such as ${\alpha}$-Terpinol, Terpinen-4-ol which are known as antioxidant substrates. Based on results, VOC emission characteristic of pine was significantly affected by coating materials with negatively in terms of ${\alpha}$-Pinene emission or positively in terms of NVOC emission. Therefore, coating material is important factor for indoor air quality when it would apply on wood products. For the future study, VOC emission characteristic of coated wood will be conducted continuously.

• Journal of the Korean housing association
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• v.17 no.2
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• pp.125-134
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• 2006

The tightness of windows have devoted to the improvement of thermal insulation and energy saving in buildings. But it is known that this tightness causes some side effects such as low ventilation, low capacity to humidity and temperature control and these are not profitable for inhabitants. To act on these side effects, Korean traditional windows which are composed of Han-Ji(Koreand traditional paper) and Chang-Sal(Korean traditional wooden frame) have been studied to get a reasonable solutions for these problems. In this study, to compare the thermal and humidity control performance of current window(12 mm pair) and Korean traditional windows, frames which are made of existing window and Korean traditional windows are adapted to scale model house and then humidity and temperature of in and out of scale model house are measured and analysed. The results of this study are followings ; 1) When Korean traditional window charges 20cm(1/8 of total window area) from total window area, Han-Ji window has higher thermal insulation than that of existing window in daytime. There is the most big thermal difference when double faced with double-ply Han-Ji window is placed to mock-up house. In night-time, the temperature difference is very small so this means that Korean traditional window is good to cover direct sunlight in daytime and reduce the temperature of balcony. One faced with one-ply han-Ji window has the best humidity penetration performance among three type of Korean traditional windows. 2) When Korean window area enlarged to 40cm(1/4 of total window area), the function of 40cm width Han-Ji window is higher than that of 20cm's. This means that enlargement of Han-Ji window cover direct sunlight more and is more efficient in humidity penetration.