• Journal of Environmental Health Sciences
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• v.49 no.2
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• pp.78-88
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• 2023

Background: Exposure to volatile organic compounds (VOCs) can have acute and chronic health effects on human beings in general and in working environments. In particular, VOCs are often emitted in large quantities in industrial settings. In such circumstances, there is a need to improve the indoor air quality at workplaces. Objectives: The purposes of this study were to verify the effectiveness of air cleaning devices in workplaces and provide alternative solutions for improving working environments. Methods: Personal exposure and area level of VOCs for workers were evaluated in a car-part adhesive process before and after installing an air cleaning device with a TiO₂-coated filter. Passive samplers and direct reading instruments were used to collect and analyze the VOCs, and the removal efficiency and improvement of air quality were evaluated. We also calculated the exposure index (EI) to assess the risk level in the workplace. Results: The removal efficiency for VOCs through the installation of the air cleaning device was approximately 26.9~69.0% as determined by the concentration levels before and after installation. The measured substances did not exceed the exposure limits for the work environment and the EI was less than 1. However, carcinogenic substances such as benzene, formaldehyde, carbon tetrachloride, and trichloroethylene were detected. Conclusions: The application of an air cleaning device can be a solution for controlling the indoor air quality in a workplace, particularly in cases where ventilation systems cannot be installed due to process limitations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.9
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• pp.1195-1209
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• 2000

The purpose of this study is to develop the non-gravity fluidized dryer. In this non-gravity fluidized dryer the fluidized zone is produced by two paddles in mixer, which maximizes the surface area of materials and then heated air through the guiding panels dehumidify them. This can conduct the drying process quickly and control moisture contents to lower limits. The ventilation system is closed loop system, which can be changeable to open system, and can be used as a multi-purposed dryer in which mixing, drying, granulating and cooling process is conducted. In order to develop the non-gravity fluidized dryer, in the first fundamental experiments were performed to mixing accuracy and then the other parts of dryer and control system were examined to check whether they were designed properly and operated harmoniously with mixer. Also the preparatory experiments were fulfilled to examine the efficiency and reliability of the dryer. Lastly, on the basis of preparatory experiments, performance test for the non-gravity fluidized dryer carried out for the variation of the initial moisture contents, desired moisture contents, heated air velocity and heating temperature.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.25 no.4
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• pp.542-553
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• 2015

Objectives: Many types of dust collector are used for industrial ventilation, with the most common types being the cylinder bag filter system, rectangular bag filter system and cylinder type cartridge filter system. The cylinder type cartridge bag filter, which has more filtering area than other types of bag filter, can increase the pulse time and extend the useful life of the filter. This can save operational costs and installation area. Materials: This study used cylinder type cartridge bag filter equipment and tested the impact of vibration level and filter pressure with different pulse jet cleaning conditions. The final, cleaning efficiency was calculated through input dust mass and cleaning dust mass Conclusions: Two optimum cleaning condition groups were found. The first condition group was $3kgf/cm^2$ pulse pressure, 15 cm pulse distance, 0.2 s pulse time with an H-10 type nozzle. The second condition group was $3kgf/cm^2$ pulse pressure, 15 cm pulse distance, 0.3 s pulse time with an H-10 type nozzle.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2009.11a
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• pp.213-216
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• 2009

The purpose of this study is analyzing temporal flow about 20 detailed performance items in the "Housing Performance Grading Indication System". This study try to figure out situations according grade in detailed performance item and to analyze change item about 112 cases(2 cases in 2006, 15 cases in 2007, 46 cases in 2008, 49 cases in 2009), from January 9, 2006 which system is undertaken, to October, 2009. This system consists of 5 main performance section, 14 performance categories and 20 detailed performance items. 5 main performance parts are Noise and Acoustics(Light-weight impact sound control, heavy-weight impact sound control, sound control of toilet, sound control of party wall), Long-life(flexibility, remodeling & maintenance, durability), Landscape & Indoor Environment(landscape, formaldehyde control & ventilation, daylighting, thermal environment), Welfare & Barrier-free(playground and community center, welfare space, barrier-free design), Fire Safety(fire safety, safe place, fire-resisting quality). Total efficiency about housing can understand systematically of 20 perfomance items though this research.

• Journal of the Korean housing association
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• v.23 no.6
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• pp.21-30
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• 2012

In foreign countries, the use of containers has already been stabilized with their advantages utilized in various forms. Containers are also utilized in Korea as various forms of architecture, but domestic container buildings have poor public consciousness so as to be limitedly utilized as temporary structures based on economic efficiency. Besides, there is the lack of research and development on them. Particularly, despite the advantages of containers as housing facilities, the use of containers as short- or middle-term temporary housing is limited and does not spread. Also, compared to general housing, containers have lower quality of physical environment and even frequently bring about negligent accidents such as fire and electric shock. Thus, this study intends to identify the actual condition of using container houses, the problems in using them, and the direction of improving their residential environment. For this purpose, it analyzes the present condition and characteristics of domestic container housing, and derives conclusions from the focus group interview with 23 residents who have lived in Seoul and Gyeonggi-do for over a year about such survey items as daylighting, ventilation, privacy condition, water service and sewerage, insulation, soundproofing, view, and room scale.

• The Korean Journal of Food And Nutrition
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• v.11 no.5
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• pp.528-535
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• 1998

This study was conducted to provide some basic information for promoting efficiency in university food services. Subjects were 309 students of A, B and C university. The survey was done by questionaires, and the data were analyzed by SAS program. The quantity and nutritional values of food was evaluated as appropriate but temperature and freshness of food, use of seasonal food, variety of menu were indicated as unsatisfactory. Male students marked lower points on the price but female students gave lower scores for variety of menu and use of seasonl food. Employee hygiene fast service and neatness and kindness of workers were evaluated as appropriate but food sanitation and cleanness of dishes were indicated as unsatisfactory. A and B university students scored low marks on food sanitation. Female students scored higher marks on the employee's neatness. Arrangement of tables and chairs, location of returning utensils, location of counter use of menu board and ventilation facilities were scored as average but interior decoration and heating facilities were scored as low level. Students of a school scored low mark on the arrangement of tables, location of counter, heating facilities and interior decoration but students of B school scored low mark on the use of menu board. Calmness and comfortableness of dining hall was unsatisfactory but location of dining hall, serving time and waiting time were evaluated as appropriate. In conclusion improvements for temperature and freshness of food, use of seasonal food, variety of menu, food sanitation, cleanness of dishes, interior decoration, heating facility and resting area were indicated as necessary.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.97-98
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• 2011

The HVAC(Heating Ventilation and Air conditioning) system is controlled by two ways, one is ON/OFF control and the other is PWM inverter with V/F. Control of blower with the use of PWM inverter has quite some benefits such as the capability of changing speed, high efficiency and reduced noise level compared with ON/OFF control. But if blower is operated at low speed, high THD generated by decrease of ma, and output voltage lowered in proportion to frequency. To solve these problems, filter should be installed at the output stage of inverter, which can decrease THD but has problems such as increase of volume size and additional braking resistance. This paper proposes the PWAM method which can reduce THD instead of installing the filter at the output stage of inverter. The proposed PWAM method is an inverter modulation method that fixes the modulation index of inverter to reduce THD by varying DC link voltage of inverter unlike conventional PWM method. Finally, the validity of proposed PWAM methods verified by experiments.

• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.223-227
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• 2005

A PCV valve is a part to control the flow rate of Blowby gas in a PCV system. A PCV system re-burns Blowby gas with fuel in a combustion chamber. Some gas enters to a crankcase room through the gap between piston ring and engine cylinder wall. This gas si called 'Blowby gas'. This gas causes many problems. In environmental view, Blowby gas includes about $25\~35\%$ hydrocarbon{HC) of total generated HC in an automobile. Hydrocarbon is a very harmful pollutant element in our life. In mechanical view, Blowby gas has some reaction with lubricant oil of crankcase room. Then, this causes lubricant oil contamination, crankcase corrosion and a decrease fo engine efficiency. Consequently, Blowby gas must be eliminated from a crankcase room. In this study, we simulated internal flow characteristics in a PCV valve according to spool dynamic behavior using local remeshing method And, we programmed our sub routine to simulate a spool dynamic motion. As results, spool dynamic behavior is periodically oscillated by the relationship between fluid force and elastic force of spring. And its magnitude is linearly increased by the differential pressure between inlet and outlet. Also, as spool is largely moved, flow area is suddenly decreased at orifice. For this reason, flow velocity is rapidly decreased by viscous effect.

• Journal of Biosystems Engineering
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• v.15 no.2
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• pp.134-142
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• 1990

This study was carried out for the development of greenhouse temperature control system by modifying an APPLE-II microcomputer attached with several interface systems. The interface systems are composed of 12 bit A/D converter, output port, multiplexer, time clock, etc. Under the operation of developed system, the greenhouse temperature was to be manipulated within the setting temperatures assumed to be appropriate for certain plant growth. The temperature control equimpents installed in the greenhouse are one-speed propeller type fan and two-phase electric heater, which are selectively started or stopped according to the control logic programmed in the control system. The results are summarized as follows : 1. The difference between two temperatures measured by the developed system and the self-recording thermometer calibrated with standard thermometer was less than $1^{\circ}C$. 2. When the temperature were measurd by 12 bit A/D converter and both electric heater and ventilation fan were controlled by developed ON/OFF logic, greenhouse temperature showed narrow fluctuation bands of less than $1^{\circ}C$ near the setting temperatures. 3. The temperature acquisition and control system developed in this study is expected to be applicable to environment control system such as greenhouse only by modifying the logic based on long term experimental data. 4. In order to reduce the measurement error and to increase the system control efficiency, it is recommended that continuous study should be carried out in the aspect of eliminating various systematic noises and improving the environmental control logic.

• Journal of Environmental Impact Assessment
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• v.15 no.6
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• pp.417-423
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• 2006

The purification ability of indoor plants for volatile organic compounds was investigated. Philodendron selloum and Spathiphyllum sp. were tested for removal of toluene and trichloroethylene in the artificially contaminated reactor under laboratory conditions. Each plant was placed in right side of the reactor and the TCE and toluene concentration change with time were monitored. In the reactor with Philodendron, the TCE concentrations of left and right sides were compared to examine the removal effects by plant. In the reactor with Spathiphyllum, air was circulated before sampling, and thus average removal effects by plants on target VOC were observed. Both plants showed clear effects on removal of VOCs from contaminated indoor air. The removal efficiency of Philodendron and Spathiphyllum were similar and showed 30 - 46% and 31 - 47% of purification effects, respectively. The results of this study showed that air purification using plants is an effective means of reduction on indoor VOCs concentration level and reduce related health risk though, supplementary purifying aids or proper ventilation were also suggested.