• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.17 no.3
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• pp.212-223
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• 2007

18 Local exhaust ventilation systems in 10 melting companies located in an industrial complex were tested to know the status of maintenance. Test items were fan flowrates, fan static pressures, rotational speeds and differential pressures of bag filters. Only 22% of the tested fans has more than 80% flowrate efficiency. 44% of the fans has lower than 60% efficiency. The performance of the fans are not in a good status. For the fans with lower than 60% efficiency, the analysis shows that the lower flowrate might be caused by the degradation of fan performance. On the other hand, for the fan s with higher than 60% efficiency, the main cause of flowrate reduction might be too much pressure losses due to clogging of filter bags. The degradation of fans usually lead the reduction of hood capture efficiency, resulting in the increase of contaminant concentrations in workplace. To keep fans in good status, self inspections should be periodically conducted. This inspection should include the measurements of flowrate and pressures. The most important thing to be performed is the initial test of local exhaust ventilation system because the initial test data should be used to know the level of system degradation.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.478-481
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• 2011

This study is intended to evaluate and optimize the characteristics of smoke spreading and the appropriateness of evacuation time extended by operation of smoke control system during fire within the underground space of the building structured in compliance with the smoke control system performance criteria from the local fire safety standard, which has been currently applied to the buildings in Korea. Using the heat release per unit weight of the combustibles, a numerical analysis both in case of smoke control system in operation and the system not in operation was carried out at the several different shopping malls. From the viewpoint of securing the evacuation time, the results were compared in an attempt to assess the appropriateness of the fire safety criteria.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1250-1254
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• 2004

To develop more compact and light generators which have high capacity, the most important thing that should be considered is the inner cooling system. Under all circumstances, the temperature of rotor and stator windings must be kept below the maximum temperature of insulation to maintain reliability and prolong durability of the machine. Therefore, the development of more effective cooling system and the exact prediction of windings are essential to produce our unique generator model which is reliable and competitive in international market. In this study, the flow of cooling air and the temperature distribution of winding is analyzed by using computational fluid dynamics. This analysis can lead to optimize the structure of cooling system and predict a local temperature rise.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.2
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• pp.136-141
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• 2012

Performance improvement of local exhaust system used in toilet and cooking place are main concern in a field of ventilation. In Korea, There are many high riser residential apartments in recent years. These buildings were not viewed as being major contributors to exhaust pollutants producted in indoor. It was because many engineers thought that exhaust in high riser building depends on stack effect. This study investigates on the performance improvement of terminal device, roof fan, of vertical spiral duct used in high riser residential apartments. This paper focuses mainly on the effect of accessories, number or shape of blades, composed of roof fan with function of exhaust air volume of toilet and cooking place. Roof fan with 10 blades is observed at optimum exhaust performance in this study.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.154-158
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• 2009

The vortex ventilation system (VV) which uses a rotating finned swirler installed coaxially with the exhaust duct is a very effective local ventilator. VV can enhance the capture depth by a factor of 3-5 compared to the conventional exhaust hood, in the absence of any solid walls nearby. In real situations there may exist ceiling, side wall and floor, all of which can affect the flow field and suction performance by way of the no-slip condition on the walls. 3D CFD simulation was performed in order to see the effect of the floor on the capture performance of the VV. The presence of floor reduced suction flow velocity, and increased the critical rotational speed which is the rotational speed required for stable vortex formation. Flow velocity profile along the axis could be well approximated by a universal functional form when the distance from the exhaust inlet is non-dimensionalized by the distance to the floor. Capture depth, define by the distance from the exhaust inlet to a point of velocity decreased to 10% of that at the inlet, is reduced by about 10% when the floor distance is 6 times the exhaust hood diameter.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.4
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• pp.452-463
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• 2019

Objectives: The purpose of this study is to evaluate airborne concentrations of volatile organic compounds(VOCs) during nail art practice by college students. Methods: Personal samples for students were measured using passive samplers(OVM 3500) during three kinds of practice, including polish nail, gel nail and acrylic French sculpture at two universities located in Gyeongsangbuk-do Province. We also monitored area concentrations using active samplers and real-time total VOC monitors(ppbRAE 3000). All samples were analyzed with a gas chromatography flame ionized detector. Statistical analysis for monitored data were conducted using a web-based Bayesian toolkit, EXPOSTATS(www.expostats.ca). Results: Twenty-four personal samples and ten area samples were collected and five chemicals(acetone, butyl acetate, ethyl acetate, ethyl methacrylate(EMA) and methyl methacrylate(MMA)) were detected. Acetone was detected in all personal samples and ranged from 2.58 ppm to 50.3 ppm. EMA was detected in all personal and area samples with a maximum concentration of 9.78 ppm during acrylic French sculpture. Personal exposure levels to acetone, butyl acetate and mixtures were significantly higher with high occupant density (p<0.05). Geometric mean (GM) concentrations of 3.61 ppm for EMA personal samples were significantly higher than that of area samples, 1.5 ppm (p<0.05). Since there was no local ventilation, total VOC concentration continued to increase as the practice progressed. Conclusions: In order to minimize VOCs exposure for trainees, it is necessary to introduce a local ventilation system and maintain adequate occupant density.

• Journal of the Korean Society for Nondestructive Testing
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• v.37 no.1
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• pp.29-36
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• 2017

Recently, KTX (Korean Train Express) train stoppage accidents were mainly caused by malfunctioning equipment, aging and cracking of railway vehicles, crack breakages of brake disks, and breakages of brake disks. Breakage of brake disk can cause large-scale casualties such as high-speed collision and concern about derailment by hitting lower axle and wheel. Therefore, in this study, a brake disk with solid and ventilation type, which is the brake disk of a KTX train was modeled, and a dynamometer system was constructed to operate the disk. A Rayleigh wave was used to inspect the surface of the brake disk. An ultrasonic inspection module was developed for the brake disk by using a local immersion method due to the difficulty involved in ultrasonic inspection using an existing immersion method. In addition, the surface defects of the brake disk were evaluated using a dynamometer mock-up system and an ultrasonic inspection module of the brake disk.

• KIEAE Journal
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• v.10 no.3
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• pp.17-26
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• 2010

This study aims at exploring the characteristics of the Usonian houses of Frank Lloyd Wright from an ecological viewpoint. After considering the definition and application of ecological architecture through literature review, 28 Usonian houses were selected and analyzed for the study. Also, nine Usonian houses, which clearly have ecological and historical importance, were visited and more thoroughly analyzed. The result shows that Usonian houses are ecological in terms of 1) the relationship among nature, landscape and house, 2) the orientation, natural light and natural ventilation, 3) the use of natural local materials including wood, stones and bricks, 4) the use of floor heating (the On-dol system inKorea), 5) the human scale, 6) the use of the board and batten unit (an early system of prefabrication), and 7) the openness and flexibility of floor plans.

• Journal of the Korea Society of Computer and Information
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• v.23 no.11
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• pp.143-149
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• 2018

The purpose of this study is to propose a management method to maintain the pleasant indoor air quality of the dental clinic by measuring and analyzing the indoor air quality of the dental clinic. The measurement was conducted in two rooms, a lobby where many residents stay in the reception room for waiting for medical treatment, and a VIP room where treatment activities are mainly performed. Measurement items are Temperature, Humidity, $CO_2$, CO, $NO_2$, $CH_2O$, VOC, $PM_{10}$ and measurement were taken on April 27, 2018. As a result of analyzing the temperature and humidity of the dental clinic, it was analyzed that the average indoor temperature was maintained at $25^{\circ}C$ and the humidity was kept at around 50%, maintaining proper indoor temperature and humidity environment. $CO_2$ was 855ppm in the VIP Room, which satisfied the maintenance standard. In the case of the lobby, it was analyzed to be 1,160ppm, which exceeded the maintenance standard and it is judged that the carbon dioxide generated by the respiration of the people staying in the lobby is the main reason. The mean concentration of formaldehyde in the VIP room was analyzed as $436{\mu}g/m^3$, exceeding the maintenance standard, and $2,100{\mu}g/m^3$ for the VOC exceeded the recommended standard. It was analyzed that the concentration was relatively higher due to the use of disinfectant and other drugs. The mean concentration of PM-10 in the lobby was analyzed as $65{\mu}g/m^3$ and it was analyzed that it satisfied the maintenance standard. To maintain a pleasant indoor air quality in a dental clinic it is necessary to minimize the effects of formaldehyde, VOC, $CO_2$ in the VIP rooms and lobby. For this purpose, the entire ventilation system and air purification system of the dental clinic should be installed. In case of the VIP room, local exhaust ventilation should be installed and workers should wear personal protective equipment.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.6 no.1
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• pp.179-213
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• 1984

The history of recording and conserving for maintenance the human's memory from ancient times to modern's has brought about a lot of changing process of the recorded information media with developing in culture, and each society has made important recorded materials in his library as essentially the social apparatus. But most of them that were damaged by factors of the natural disaster, humidity, temperature, light, fungi and insects in the library, and were resulted in deterioration and losing the numerous materials. For removing the inevitable phases repeated, there are studying for counterplan of the fundamental environment factors about preservation, restoration and chemical research of materials in advanced countries, but I get a few researches about protecting the cultural properties. Therefore I research the survey of the actual conditions on 72 university libraries centering around them, and then I have researched the collection rate 81 percent, 58 university libraries. (local : 35, in seoul : 23) As the result of this research, I propose the model of the environment factors of conserving the library materials. 1) To apply the equipment of processing the radiant energy to the new construction and buildings. 2) To remove factors that occur fungi and insects by facilities being controlled relative humility, temperature, and to equip the ventilation arrangement in the library. 3) To shelve all acquired and bound materials after proceeding the vacuum fumigator. 4) Those who want to enter into the library stack were surely taken in sterilzing their hands and shoes, and must put on the gown. 5) To use the vacuum dusting thing (machine) for removing the dust without spreading out the floor of the library at any time. 6) To set up the gas automatic fire extinguisher worked by smoke sensor. 7) To assist the research into the preservation, natures and environment of recorded materials, and to supply financial funds for librarian. 8) To hold regularly the workshop be able to educate the methods of preservation materials by the constant system. (Library Association) 9) To add to responsibilities on certification of preservation materials for librarian. 10) To hold the constant committee system in each library. 11) To keep up with the ideal environment (humidity, temperature, light, ventilation, etc.) of preservation materials in the arrangement room, and to put on the gown.