• Journal of Mushroom
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• v.15 no.1
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• pp.14-20
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• 2017

The oyster mushroom cultivation house typically has multiple layers of growing shelves that cause the disturbance of air circulation inside the mushroom house. Due to this instability in the internal environment, growth distinction occurs according to the area of the growing shelves. It is known that minimal air circulation around the mushroom cap facilitates the metabolism of mushrooms and improves their quality. For the purpose of this study, a CFD analysis FLUENT R16 has been carried out to improve the internal environment uniformity of the oyster mushroom cultivation house. It is found that installing a section of the working passage towards the ceiling is to maintain the internal environment uniformity of the oyster mushroom cultivation house. When all the environment control equipment - including a unit cooler, an inlet fan, an outlet fan, an air circulation fan, and a humidifier - were operated simultaneously, the reported Root Mean Square (RMS) valuation the growing shelves were as follows: velocity 23.86%, temperature 6.08%, and humidity 2.72%. However, when only a unit cooler and an air circulation fan operated, improved RMS values on the growing shelves were reported as follows: velocity 23.54%, temperature 0.51%, and humidity 0.41%. Therefore, in order to maintain the internal environment uniformity of the mushroom cultivation house, it is essential to reduce the overall operating time of the inlet fan, outlet fan, and humidifier, while simultaneously appropriately manage the internal environment by using a unit cooler and an air circulation fan.

• Journal of the Korean Solar Energy Society
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• v.21 no.1
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• pp.33-42
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• 2001

The paper discusses the modelling of the thermal storage roof with the air circulation system. In this system, the fully glazed absorber plate is put on the top of the conventional pitch roof made of massive concrete and acts as a solar air heater. Solar radiation collected into absorber is stored in the roof structure by radiation and convection so that it reduces the nighttime heating load through the roof. Another part of the energy is also transmitted to internal air drawn into the channel and is then introduced Into the room. To analysis the system, the energy balance equations are developed and are solved using a finite difference method. The calculation results show a good agreement with the measured ones obtained from our experiments. From the results, it is seen that the thermal storage roof with the air circulation system reduces significantly the conductive heat loss compared with that for the conventional roof and has the instantaneous solar collection efficiency of about 30%.

• Journal of Korean Society on Water Environment
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• v.26 no.1
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• pp.81-88
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• 2010

This study was conducted to find the capability of comparison of overall oxygen transfer coefficient in the membrane coupled high performance reactor (MPHCR) in treating high organic loading wastewater. Effluent quality had been analyzed while the influent organic loading rate was changed from 2 to $7kg\;COD/m^3{\cdot}day$. The oxygen transfer coefficients had been investigated using two-phase nozzle for operating variables which were internal circulation flowrate (5~8 L/min), air flow rate (0.0125~0.2 L/min), liquid temperature ($10{\sim}20^{\circ}C$), and pure-oxygen flow rate (0.0125~0.2 L/min). The overall oxygen transfer coefficient was increased with flowrate of internal circulation and air and high temperature. Especially, internal circulation flow rate showed distinct effect on overall oxygen transfer coefficient due to an increase of gas holdup and air-liquid contract area by two-phase nozzle. In the high range of organic loading rate from 4 to $7kg\;COD/m^3{\cdot}day$, the removable efficiency of COD was 91%. Conventional activated sludge process usually treat organic loading from 0.32 to $0.64kg\;COD/m^3{\cdot}day$ however, the MPHCR can treat 10 to 20 times higher if it would be compared to the conventional activated sludge process. Foaming problem often happened and caused biomass wash out of the reactor, therefore, the foaming should be controlled for the enhanced operation.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.3
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• pp.240-249
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• 2009

HRSG(Heat Recovery Steam Generator) building is large enclosed structure included various heat sources. This building needs to appropriately keep internal air temperature for worker's safety and operability of control devices. In this study, ventilation analysis is performed to find proper ventilation method for temperature control. Ventilation analysis is applied to entire internal space of the building with standard $k-{\varepsilon}$ model and enhanced wall treatment because of large size of the structure. And the ventilation method is considered natural and forced convection with two louver structures which has damper or not. Louver structure affect directly air circulation in near HRSG and lower region of the building. Forced ventilation provides strong inertial force which cause upward airflow. From the analysis, it is found that design requirement for internal air temperature can be satisfied by forced ventilation method with louver structure without damper.

• Design & Manufacturing
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• v.14 no.2
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• pp.28-33
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• 2020

Recently, as the income level and quality of life have improved, the desire for a pleasant environment has increased, and a deodorization plan is required through thorough prevention and diffusion of odorous substances in waste treatment facilities recognized as hateful facilities, appropriate collection, and selection of the right prevention facilities. In this study, a waste disposal facility was modeled and computerized analysis for odor and ventilation analysis was conducted. Numerical analysis of the waste treatment facility was performed at the size of the actual plant. CATIA V5 R16 for numerical model generation and ANSYS FLUENT V.13 for general purpose flow analysis were used as analysis tools. The average air-age of the internal was 329 seconds, and the air-flow velocity was 0.384m/s. The odor diffusion analysis inside the underground pump room showed congestion-free air circulation through streamline distribution and air-age distribution. This satisfies the ASHRAE criteria. In addition, the results of diffusion analysis of odorous substances such as ammonia, hydrogen sulfide, methyl mercaptan and dimethyl sulfide were all expected to satisfy the regulatory standards. Particularly in the case of the waste loading area, the air-flow velocity was 0.297m/s, and the result of meeting the regulatory standards with 0.167ppm of ammonia, 0.00548ppm of hydrogen sulfide, 0.003ppm of methyl mercaptan, and 0.003ppm of dimethyl sulfide was found.

• Journal of Bio-Environment Control
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• v.24 no.2
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• pp.128-133
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• 2015

Mushrooms can grow in nature when adequate temperature and humidity are maintained, but such condition can be satisfied for only a short period of time on an annual continuum. Therefore, it can be deemed that a majority of the distributed mushrooms in the current market are produced in an artificially manipulated environment. This study was conducted to resolve the problem of the Oyster mushroom cultivation house's internal temperature and humidity imbalance, where the Oyster mushrooms are cultivated in a multi-layered shelves. The air circulation fans were installed to improve the air uniformity of the Oyster mushroom cultivation house by using multi-layered shelves. During the experiment, the ambient temperature and the ambient relative humidity ranged from $5.2^{\circ}C$ to $20.4^{\circ}C$ and 40% to 100% respectively. Due to the change of the outdoor temperature, the internal temperature of the Oyster mushroom cultivation house also changed, ranging from $13.3^{\circ}C$ to $18.4^{\circ}C$, but the temperature gap between the different internal location of the facility during the conforming recorded time only ranged from $0.2^{\circ}C$ to $1.3^{\circ}C$, being significantly stable. The internal relative humidity, ranging from 82% to 96%, also changed due to the change of the outdoor temperature. Nevertheless, the relative humidity gap between the different internal location during the conforming recorded time only ranged from 2% to 7%. Furthermore, the research staff were able to maintain the concentration of $CO_2$ from 575ppm to 731ppm(below 1,000ppm was the goal) indicating the possibility of an even management of the internal environment by installing the air circulation fan.

• KIEAE Journal
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• v.5 no.4
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• pp.9-16
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• 2005

The purpose of this study is to analyze the safety issues with regard to architectural elements in housing. Causes of accidents and threats to health are reviewed for 'safety' aspects. Threats to health tend to draw more attention due to recent increase of SHS and its public perceptions. The majority of victims by accidents in residential houses are on juveniles aged under 14 in bathrooms and living rooms. Non-slip finish materials are recommended to floors for access and circulation and protective pads to furniture edges. Colored glass may increase the safety of the windows in the living room. Handles and non-slip mats will be a good addition for the safety. Human scale design of the kitchen system is mandatory and appropriate size of storages for hazardous equipment are to be provided. Passive air ventilation for better air quality by dwellers in residence is occasionally used whereas large-scale apartments provide mechanical ventilation to supplement the volume of fresh air. Since the internal air quality is proved one of the major causes of atopic and respiratory diseases, steady effort to achive better air quality utilizing appropriate materials, plants and equipment is mandatory. Frequent cleaning and the use of anti-fungus materials are necessary because House Dust Mites are believed to be one of main causes of such diseases.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.4
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• pp.449-455
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• 1998

A header' is the device that makes uniform flow distribution in all branches from header of heat exchangers, pipe burner or chemical equipments. In this study, experimental tests have been performed in order to investigate the flow distribution characteristics in a straight header and tapered header which have 6 and 11 glass pipe branches. The experimental equipment consists of a water circulation system where the fluid velocity in each glass pipe is measured by Ar-ion LDV system. From the experiments and the theoretical equation, it could be recommended that tapered header should be determined so that its internal velocities inside the header become uniform according to taper of the header and number of attached branches for uniform flow distribution in energy systems.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.1
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• pp.1-10
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• 1998

A header is the device that makes uniform flow distribution in all branches from header of heat exchangers, pipe burner or chemical equipments. In this study, experimental tests have been performed in order to investigate the flow distribution characteristics in a straight header and tapered header which have 6 and 11 glass pipe branches. The experimental equipment consists of a water circulation system where the fluid velocity in each glass pipe is measured by Ar-ion LDV system. From the experiments and the theoretical equation, it could be recommended that tapered header should be determined so that its internal velocities inside the header become uniform according to taper of the header and number of attached branches for uniform flow distribution in energy systems.

• Carbon letters
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• v.26
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• pp.74-80
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• 2018

The South Korean Ministry of the Environment has revised the laws relating to the management of interior air quality for multiple use facilities, and recommends maintaining carbon dioxide ($CO_2$) concentration in passenger vehicles below 1000 ppm during operation in urban areas of large cities. However, the interior $CO_2$ concentration of passenger vehicles can rapidly increase and exceed 5000 ppm within 30 min, as observed when two passengers are traveling in urban areas of the South Korean city of Jeonju with the air conditioner blower turned off and the actuator mode set to internal circulation mode. With four passengers, $CO_2$ concentration can reach up to 6000 ppm within 10 min. To counter this, when the actuator is set to external mode, $CO_2$ concentration can be maintained below 1000 ppm, even after a long period of running time. As part of the air conditioning system, alkali-treated activated carbon fiber filters are considered to be far superior to the commercial non-woven filters or combination filters currently commonly in use.