• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.277-282
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• 2016

This study was aimed to investigate the effect of air-circulation fans on air temperature and relative humidity in a single-span tomato greenhouse (W: 7m, L: 25m, H: 3.2m). According to standard of fan layout by ASAE (1997), a total of 10 fans were bilaterally arranged in 2 rows in the experimental greenhouse. The distributions of air temperature and relative humidity were measured from 6 pm to 8 am under different conditions, with and without fans. The measurement heights were 0.7m, 1.7m and 2.7m. Under the condition of "fans off", the spatial differences of air temperature and relative humidity between upper and lower sides were $1.7^{\circ}C$ and 10.8%, respectively. The operation of 10 fans showed their differences to $0.1^{\circ}C$ and 3.2%. The number of fans and installation direction were evaluated their performance on reducing the spatial variation of air temperature and relative humidity. The experimental layouts were 5 and fans in 2 rows (bilaterally) and 10 fans in the one (same) direction. Under the condition of "6 fans on" and "5 fans on", the spatial differences of air temperature and relative humidity between upper and lower side were $0.3^{\circ}C$, 3.4% and $0.3^{\circ}C$ and 4.0%. The operation of 10 fans in the one direction reduced their differences to $0.5^{\circ}C$ and 4.9%. The overall findings of this study showed that there was no significant differences under each condition. Therefore, this study suggested that it is more economic and effective to install five fans in 2 rows (bilaterally) in the greenhouse (W: 7m, L: 25m, H: 3.2m).

• Journal of Bio-Environment Control
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• v.16 no.4
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• pp.291-296
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• 2007

This study was conducted to investigate the effects of horizontal air flow produced by circulation fans on horizontal and vertical profiles of meteorological factors. The three-dimensional distributions of air speed, air temperature, relative humidity and carbon dioxide $(CO_2)$ concentration were measured with and without the fans in operation. The uniformity of the spatial distribution of meteorological factors decreased as the outside air temperature decreased. In "fans off" condition, spatial variations of $4.7^{\circ}C$ in air temperature, 19% in relative humidity were detected. When the fans were operated, these variations were reduced to 2.2 and 6.3%, respectively. As the fan capacity increased, the difference in air temperature among sampling points decreased. The fan capacity of $0.0104m^3{\cdot}s^{-1}{\cdot}m^{-2}$ was enough to obtain a reasonable air flow in greenhouse. The vertical profiles of air temperature and $CO_2$ concentration were reasonably uniform regardless of measurement height and fan capacity. Further researches on the position of fans to reduce the difference in air temperature along the width and the effects of using a larger number of smaller fans are required.

• Journal of Bio-Environment Control
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• v.10 no.1
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• pp.23-29
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• 2001

This experiment was conducted to investigate to investigate the effect of air circulation and forced ventilation of greenhouse on the development of fermented fruits in an oriental melon. An air circulation system and a forced ventilation system were operated during 09:30~17:00 at a 15 min. interval from Apr. 6, 5 days after fruit setting, to Jun. 29, everyday except rainy days. Wind velocities in the greenhouse were 0.06~0.08, 0.24~0.32, and 0.60~0.72m.s$^{-1}$ in the naturally ventilated (control), in the air circulated, and including leaf length and width, were observed between treatments. However, the amount of xylem exudate increased in the air circulated treatment as compared to the control. Percent of fermented fruits significantly decreased in the air circulated treatment as compared to the control. The forced ventilation treatment showed no significant difference in percent of fermented fruits as compared to the control or to the air circulated treatment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.148-154
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• 1996

가정용 냉장고에 있어서 정음화를 위한 다각적인 노력이 냉장고의 주요 소음원이라고 할 수 있는 압축기, 냉기 순환용 팬, 압축기 냉각용 팬 및 냉매 순환용 파이프 방진구조 등의 개선을 통하여 국내외적으로 상당한 진척을 보이고 있다. 이러한 소음원들의 특징은 각각이 특정한 목적에 의하여 작동하는 하나의 구동부이거나 이러한 구동부와의 직접적인 연결에 의해 가진되는 경우로서 Airborne Noise나 Structureborne Noise를 발생시키고 있다. 본 논문에서는 이러한 압축기나 팬이 꺼진 상태에서 냉장고의 싸이클상에 열교환용 냉매가 봉입된 상태에서 압축기가 운전시 형성되었던 싸이클상의 고압 및 저압측의 압력 차이에 의하여 증발기의 Accumulator내에 형성된 Sleeve(이하, 삽입관 .PHI.1.5 Hole)에 의해서 발생되는 Bubble 소음에 대한 실험적 규명과 소음 측정을 통한 주파수 분석을 하였으며, 이러한 Bubble 소음 발생시 싸이클상의 온도 및 압력값을 측정하여 Strasberg에 의해 도출된 선형화된 식을 이용하여 Bubble 소음 발생시 주파수 분석을 통한 Bubble Size를 결정하였고, Bubble 소음 발생의 직접적인 원인으로 작용하는 Orifice를 제거하여 Bubble 소음의 개선 정도를 비교 검토하였다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.322-324
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• 2008

현재 배전용변전소 대용량변압기 냉각방식은 주로 유입자냉식, 유입풍냉식, 송유풍냉식 및 수냉각 방식이 채용되고 있다. 유입풍냉식의 경우는 대기 공기의 자연대류 또는 냉각팬에 의한 강제대류에 의해 방열기 내부로 유입된 절연유의 온도를 낮추는 방식이고 송유풍냉식은 변압기 내부 절연유를 강제순환 시키면서 냉각팬을 가동하는 방식이다. 도심지 복합건물내 주변압기 냉각은 수냉식을 채용하여 절연유를 강제로 순환시키면서 열교환기 2차측에 냉각수를 순환시켜 열교환기 내로 유입된 절연유의 온도를 낮추는 방식이다. 그러나 도심지 변전소의 냉각방식 채택에 있어 냉각성능, 소음, 설비의 건전성등 여러 가지 문제점이 드러나 새롭고 획기적인 냉각방식이 요구되고 있다.

• 농업기술회보
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• v.43 no.4 s.505
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• pp.44-45
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• 2006

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2010.10a
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• pp.323-324
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• 2010

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.3
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• pp.165-172
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• 2017

In this study, centrifugal fan blades used to circulate cold air inside a household refrigerator were optimized to achieve high performance and low noise by using the response surface method, which is frequently employed as an optimization algorithm when multiple independent variables affect one dependent variable. The inlet and outlet blade angles, and the inner radius, were selected as the independent variables. First, the fan blades were optimized to achieve the maximum volume flow rate. Based on this result, a prototype fan blade was manufactured using a 3-D printer. The measured P-Q curves confirmed the increased volume flow rate of the proposed fan. Then, the rotation speed of the new fan was decreased to match the P-Q curve of the existing fan. It was found that a noise reduction of 1.7 dBA could be achieved using the new fan at the same volume flow rate.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.4
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• pp.167-173
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• 2018

We propose an air purification system that utilizes aerial plant parts and root zone of indoor plants where light is insufficient and air circulation is bad. In order to maximize the air purification effect of the plant, the aerial plant parts illuminates mixed light combining blue and green LED and CRI(Color Rendering Index) LEDs close to natural light, respectively. And the root zone was forcibly circulated by the fan to use the soil as a filter. The indoor air purification system combined with the light source and the fan removed most polluted air in the shortest. In the case of mixed light and CRI LEDs of indoor air purification system, fine dust decreased by 14%, 14.2%, and TVOC(Total volatile organic compounds) decreased by 7.5% and 9.4%, respectively. In the experiment in which the fan was operated for 15 minutes, the TVOC decreased to 97.8%. The photosynthesis of the plant and the use of soil as a filter were able to purify polluted air in a short time. And the fan's temporary operation gave the similar effect of continuous operation.

• Journal of Internet Computing and Services
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• v.16 no.1
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• pp.57-65
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• 2015

As information technology fusion is accelerated, the researches to improve the quality and productivity of crops inside a plant factory actively progress. Advanced growth environment management technology that can provide thermal environment and air flow suited to the growth of crops and considering the characteristics inside a facility is necessary to maximize productivity inside a plant factory. Currently running plant factories are designed to rely on experience or personal judgment; hence, design and operation technology specific to plant factories are not established, inherently producing problems such as uneven crop production due to the deviation of temperature and air flow and additional increases in energy consumption after prolonged cultivation. The optimization process has to be set up in advance for the arrangement of air flow devices and operation technology using computational fluid dynamics (CFD) during the design stage of a facility for plant factories to resolve the problems. In this study, the optimum arrangement and air flow of air circulation fans were investigated to save energy while minimizing temperature deviation at each point inside a plant factory using CFD. The condition for simulation was categorized into a total of 12 types according to installation location, quantity, and air flow changes in air circulation fans. Also, the variables of boundary conditions for simulation were set in the same level. The analysis results for each case showed that an average temperature of 296.33K matching with a set temperature and average air flow velocity of 0.51m/s suiting plant growth were well-maintained under Case 4 condition wherein two sets of air circulation fans were installed at the upper part of plant cultivation beds. Further, control of air circulation fan set under Case D yielded the most excellent results from Case D-3 conditions wherein air velocity at the outlet was adjusted to 2.9m/s.