• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1994.11a
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• pp.67-69
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• 1994

4계절이 뚜렷한 우리나라의 겨울철은 작물생산에 단경기이었으나, 플라스틱 하우스나 유리온실이 보급되면서 겨울철 단경기가 해소되었다. 그러나 이리한 시설들은 PE 또는 유리 등의 피복자재를 사용하여 여름철의 경우 막대한 일사부하로 온실 내부온도가 외부온도보다 높아져 작물생육에 열악한 환경을 조성한다. 이에 fog and pad system, fan and pad system 과 heat pump 등이 개발되어 있으나 실용적으로 도입되지 못하고 있는 실정이다. (중략)

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.243-251
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• 2015

This study aimed to determine the effects of root zone cooling using air duct on air temperature distribution and root zone and leaf temperatures of sweet pepper (Capsicum annum L. 'Veyron') grown on coir substrate hydroponic system in a greenhouse. When the air duct was laid at the passage adjacent the slab, the direction of air blowing was upstream at $45^{\circ}$. The cooling temperature was set at $20^{\circ}C$ for day and $18^{\circ}C$ for night. For cooing timing treatments, the cooling air was applied at all day (All-day), only night time (5 p.m. to 1 a.m.; Night), or no cooling (Control). The air temperature inside the greenhouse at a height of 40 and 80cm above the floor, and substrate and leaf temperatures, fruit characteristics, and fruit ratio were measured. Under the All-day treatment, the air temperature was decreased about $4.4{\sim}5.1^{\circ}C$ at the height of 40cm and $2.1{\sim}3.1^{\circ}C$ at the height of 80cm. Under the Night treatment, the air temperature was decreased about $3.4{\sim}3.8^{\circ}C$ at the height of 40cm and $2.2{\sim}2.7^{\circ}C$ at the height of 80cm. The daily average temperature in the substrate was in the order of the Control ($27.7^{\circ}C$) > Night ($24.1^{\circ}C$) > All-day ($22.8^{\circ}C$) treatment. Cooling the passage with either upstream blowing at $45^{\circ}$ or horizontal blowing at $180^{\circ}$ was effective in lowering the air temperature at a height of 50cm; however, no difference at a height of 100cm. Cooling the passage with perpendicular direction at $90^{\circ}$ was effective in lowering the air temperature at the height between 100 and 200cm above the floor; however, no effect on the temperature at the height of 50cm. A greater decrease in leaf temperature was found at 7 p.m. than that at 9. a.m. under both All-day and Night treatments. Fresh weight partitioning of fruit was in the order of the All-day (48.6%) > Night (45.6%) > Control (24.4%) treatment. A higher fruit production was observed under the All-day treatment, in which the accumulated average temperature was the lowest, and it may have been led to a higher proportion of photosynthate distributed to fruit than other treatments.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1993.10a
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• pp.15-16
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• 1993

자연광 이용 식물공장의 주년 이용을 위해서는 하기주간의 냉방은 최대 과제중의 하나이다. 일반적으로 하기주간의 냉방방법으로는 냉동기(또는 냉수)에 의한 것과 세무의 증발냉각에 의한 것으로 나누어 볼 수 있다. 필자 등은 1992년 일본 식물공장학회지에 Heat pump를 이용한 냉수냉방과 세무냉방을 이용한 국소냉방의 주요 결과중의 하나는 세무냉방에서의 토마토 과실에 송풍한 구에서는 배꼽썩이가 방지되었고, 무송풍구에서는 55% 배꼽썩이가 발생되었다. (중략)

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.474-479
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• 2005

For the safe operation of an air conditioner, the liquid car η 'over to compressors should be minimized and compressors should be operated in the specified region of suction and discharge pressures recommended by compressor manufactures. In this study, a capillary assisted tandem-type airconditioner was considered. A variable speed outdoor fan was used to control operating points of the system. Test results showed the possibilities to move system operating points to the safe region by controlling the speed of an outdoor fan.

• Journal of Bio-Environment Control
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• v.20 no.3
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• pp.176-181
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• 2011

The fan and pad evaporative cooling system is one of the main cooling methods in greenhouses. Its efficiency is very high, but it has some disadvantages as temperature gradient in greenhouse is large. This study was conducted to reduce the internal temperature gradients in the fan and pad cooling greenhouses. Experiments on cooling performance were carried out in a greenhouse equipped with air duct and integrated fan and pad system as an idea of this study. It showed that the cooling efficiency of an integrated fan and pad system was 75.7% in the first stage and 88.6% in the second stage. When this cooling system was operated for an unshaded and a shaded greenhouse, there were cooling effects of $5.7\sim7.6^{\circ}C$ and $7.4\sim9.7^{\circ}C$ to the control greenhouse, respectively. Maximum temperature differences in a cooling greenhouse, with a length of 18m, were $1.6\sim1.7^{\circ}C$ for shaded conditions and $2.3\sim2.7^{\circ}C$ for unshaded conditions. This greenhouse cooling method, with air duct and integrated fan and pad system, can reduce about 40~50% of the internal temperature gradients in the usual fan and pad cooling greenhouses.

• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.349-354
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• 2013

This study examined a technique for cooling root zone aimed at lowering substrate temperature for sweet pepper (Capsicum annum L. 'Orange glory') cultivation in coir substrate hydroponics during hot season, from the $16^{th}$ of July to $15^{th}$ of October in 2012. The root zone cooling technique was applied by using an air duct (${\varnothing}12$ cm, hole size 0.1 mm) to blow cool air between two slabs during night (5p.m. to 3a.m.). Between the $23^{rd}$ of July and $31^{st}$ of August (hot temperature period), average daily substrate temperature was $24.7^{\circ}C$ under the root zone cooling, whereas it was $28.2^{\circ}C$ under condition of no cooling (control). In sunny day (600~700 W $m^{-2}{\cdot}s^{-1}$), average substrate temperatures during the day (6a.m. to 8p.m.) and night (8p.m. to 6a.m.) were lower about $1.7^{\circ}C$ and $3.3^{\circ}C$, respectively, under the cooling treatment, compared to that of control. The degree of temperature reduction in the substrate was averagely $0.5^{\circ}C$ per hour under the cooling treatment during 6p.m. to 8p.m.; however, there was no decrease in the temperature under the control. The temperature difference between the cooling and control treatments was $1.3^{\circ}C$ and $0.6^{\circ}C$ in the upper and lower part of the slab, respectively. During the hot temperature period, about 32.5% reduction in the substrate temperature was observed under the cooling treatment, compared to the control. Photosynthesis, transpiration rate, and leaf water potential of plants grown under the cooling treatment were significantly higher than those under the control. The first flowering date in the cooling was faster about 4 days than in the control. Also, the number of fruits was significantly higher than that in the control. No differences in plant height, stem thickness, number of internode, and leaf width were found between the plants grown under the cooling and control, except for the leaf length with a shorter length under the cooling treatment. However, root zone cooling influenced negligibly on eliminating delay in fruiting caused by excessively higher air temperature (> $28^{\circ}C$), although the substrate temperature was reduced by $3^{\circ}C$ to $5.6^{\circ}C$. These results suggest that the technique of lowering substrate temperature by using air-duct blow needs to be incorporated into the lowering growing temperature system for growth and fruit set of health paprika.

• Journal of Bio-Environment Control
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• v.29 no.3
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• pp.265-276
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• 2020

This study was conducted to provide a basis for raising farm income by increasing the yield and extending the cultivation period by creating an environment where crops can be cultivated normally during high temperatures in summer. The maximum cooling load of the multi-span greenhouse with a floor area of 504 ㎡ was found to be 462,609 W, and keeping the greenhouse under 32℃ without shading the greenhouse at a high temperature, it was necessary to fog spray 471.6 L of water per hour. The automatic fog cooling control device was developed to effectively control the fog device, the flow fan, and the light blocking device constituting the fog cooling system. The fog cooling system showed that the temperature of the greenhouse could be lowered by 6℃ than the outside temperature. The relative humidity of the fog-cooled greenhouse was 40-80% during the day, about 20% higher than that of the control greenhouse, and this increase in relative humidity contributed to the growth of cucumbers. The relative humidity of the fog cooling greenhouse during the day was 40-80%, which was about 20% higher than that of the control greenhouse, and this increase in relative humidity contributed to the growth of cucumbers. The yield of cucumbers in the fog-cooled greenhouse was 1.8 times higher in the single-span greenhouse and two times higher in the multi-span greenhouse compared to the control greenhouse.

• Journal of Bio-Environment Control
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• v.14 no.1
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• pp.29-37
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• 2005

In order to provide fundamental data on utilization of dehumidifier in greenhouses, a condensing type dehumidifier using ground water as a coolant was developed and tested dehumidification performance. The developed dehumidifier was applied to greenhouse with fog cooling system and effect of dehumidification on improvement of evaporative cooling efficiency was analyzed. Results of the dehumidifier performance test showed that dehumidification using ground water as a coolant was sufficiently possible in fog cooling greenhouse. When the set point temperature of greenhouse cooling was $32^{\circ}C$ and as temperatures of ground water rose from $15^{\circ}C\;to\;18^{\circ}C,\;21^{\circ}C\;and\;24^{\circ}C$, dehumidification rates decreased by $17.7\%,\;35.4\%\;and\;52.8\%$, respectively. As flow rates of ground water reduced to $75\%\;and\;50\%$, dehumidification rates decreased by $12.1\%\;and\;30.5\%$, respectively. Cooling efficiency of greenhouse equipped with fog system was distinctly improved by artificial dehumidification. When the ventilation rate was 0.7 air exchanges per minute, dehumidification rates of the fog cooling greenhouse caused by natural ventilation were 53.9%-74.4% and they rose up to 75.4%-95.9% by operating the dehumidifier. In case of using the ground water of $18^{\circ}C$ and flow rate of design condition, it was analyzed that whole fog spraying water can be dehumidified even if the ventilation rate is 0.36 exchanges per minute. As a utilization of dehumidifier, it is possible to improve cooling efficiency of fog system in naturally ventilated greenhouses.

• Journal of Bio-Environment Control
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• v.32 no.1
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• pp.15-22
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• 2023

Roses are one of the most produced flower species in the world, and cut roses are produced in the greenhouses all year round. Recently, due to the increase in the temperature in the greenhouses in summer, the quality of cut roses is seriously deteriorated, such as shortening the stem length. This study was conducted to investigate the effects of the growing seasons on the qualities of cut roses and also to test the effect of cooling at night in high temperature season on the cut flower qualities of roses. Comparing the qualities and yields of cut roses for each season, the major cut flower qualities such as flower stem length, stem diameter and fresh weight were statistically significantly decreased in roses ('Pink Beauty' and 'Pink Shine') produced in summer. The yields didn't show a statistically significant difference in both cultivars. Investigating the cut flower qualities, the flower stem length increased by 15% for 'Pink Beauty', 11% for 'Ararat', and 12% for 'Pink Shine' when treated with cooling at night in warm season than the untreated control. In addition, when treated with cooling at night in warm season, the fresh weight of all three cultivars increased by 20-30% statistically significantly than conventionally cultivated control. It is expected that cooling at night in warm season will be helpful to improve the cut flower quality deterioration in summer.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.195-202
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• 2010

Cooling air-conditioning of APC (Agricultural Products processing Center) workplace is important to improve the working environment in the summer season. As existing cooling systems for air-conditioning of whole workplace are inefficient because of their high equipment operating costs, relatively inexpensive cooling system is required. The objectives of this study were to simulate the thermal flow fields in APC workplace having the positive and negative pressure type fan and pad systems and spot cooling system by using CFD software (FLUENT, 6.2) and estimate the cooling effectiveness of respective cooling systems. The results showed that the negative pressure type fan and pad system was inappropriate for the present APC workplace because of excessive outside air influx from open gateway and the positive pressure type fan and pad system created relatively low temperature field but non-uniform velocity field at worker positions. The spot cooling system could supply cool air to worker positions with relatively constant air velocity and temperature.