• Journal of Bio-Environment Control
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• v.7 no.3
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• pp.237-245
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• 1998

Greenhouse crop production under critical summer climate In Korea has considerable difficulties because of high temperature and relative humidity. In this study, some water pipes were tested as a means of the dehumidification and increment of evaporative cooling efficiency. As a result of heat transfer characteristic analysis, overall heat transfer coefficient of copper pipe was larger than steel pipe, and estimated values were smaller than measured values. The condensed quantities of vapor were not significantly different between copper pipe and steel pipe, however dehumidifying effect by the water pipes was significantly large. It was estimated based on the results that the evaporative cooling system by the water pipe will be able to increase the evaporative cooling efficiency of about 48%, and decrease the temperature of about 1.3$^{\circ}C$.

• Journal of Bio-Environment Control
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• v.3 no.2
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• pp.128-135
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• 1994

Recently, regionally characterized greenhouses have been built every place around the country. These greenhouses insist of their higher performance by considering regional merits than the greenhouses without considering regional ones, but it is not clear. The purpose of this study was to make clear the characteristics of the regionally characterized greenhouses through the analyses of actual state and structural safety. The greenhouses were investigated and classified into wide span house, large pipe house, arched lattice house, wooden house, viniculture house, and domed pipe house. The frames of wide span house, arched truss house, viniculture house and domed pipe house were analyzed to be structurally stable under the design wind speeds and snow depths in recurrence intervals of 15 or 30 years, but large pipe house was a little unstable and required some reinforcements, and wooden house turned out to be unstable. In addition, foundations of all characterized greenhouses were stable against pull - out capacity under the design wind speeds in recurrence interval of 30 years.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2002.11a
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• pp.289-292
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• 2002

최근들어 파이프 골조의 온실 구조는 해마다 강풍이나 적설 둥으로 인한 파손으로 막대한 경제적 손실을 입고 있으며, 이러한 피해는 환경조절 및 자동화 설비의 설치에 직접적인 영향을 주는 중요한 요인이므로 시설의 구조역학적인 연구가 지속적으로 이루어져야 한다. 그러나 국내에서는 1990년대 초반 온실의 구조안전 및 구조설계 기준 설정, 자재의 규격화 및 표준화에 관한 연구가 일부 수행된 바 있으나, 파이프 골조의 온실은 구조물로서의 공학적 설계나 유지관리에 대한관심이 부족하여 시설의 구조역학적인 연구가 거의 이루어지고 있지 않는 실정이다. (중략)

• Journal of Bio-Environment Control
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• v.6 no.3
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• pp.133-142
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• 1997

Most of the greenhouses employ the roll-up type ventilation control system. Torque required to roll-up and down might be theoretically expressed with the weight times radius of the ventilation roll; however, measured torques were two times of the theoretically estimated values. As the window film of roll-up vent is used over the periods of time, the warping and crumpling of the material caused the increase of the torque in addition to a span deformation. Therefore, this study was performed to develop an empirical torque formulae to present basic torque data and to assist the development of roll-up type ventilation control system. The empirically adjusted rolling radius (r＋a) exponentially increased at the maximum span deformation. The coefficient of rolling resistance (Cr) was about 0.7―0.8 depending upon the wrinkle status of film material.

• Journal of Bio-Environment Control
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• v.24 no.2
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• pp.69-78
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• 2015

In order to provide design data support for reducing gale damage of single-span greenhouses, this paper experimentally evaluated the uplift capacity of a rafter pipe and continuous pipe foundation (anti-disaster standard), usually used for single-span greenhouses according to compaction ratio, embedded depth, and soil texture. In the reclaimed soil (Silt loam) and the farmland soil (Sandy loam), the ultimate uplift capacities of rafter pipe were 72.8kgf and 60.7kgf, respectively, and those of continuous pipe foundation were 452.7kgf and 450.3kgf, respectively at an embedded depth of 50cm and compaction rate of 85% (the hardest ground condition). The results showed that the ultimate uplift capacity of continuous pipe foundation was significantly improved at more than 6 times that of the rafter pipe. The soil texture considered in this paper had a sand content of 35%~59% and a silt content of 39%~58%, and it was shown that the ultimate uplift capacity did not have a significant difference depending on soil texture, and these results show that installing the rafter pipe and continuous pipe foundation while maintaining appropriate compaction conditions can give an advantage in securing stability in the farmland of greenhouses without significantly being influenced by soil texture. Based on the results of this paper, it was determined that maintaining a compaction rate above 75% for the continuous pipe foundation and above 85% for the rafter pipe was advantageous for securing stability in greenhouses. Especially when continuous pipe foundation of anti-disaster standard was applied, it was determined to be significantly advantageous in acquiring stability in greenhouses to prevent climate disaster.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2001.11a
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• pp.65-70
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• 2001

우리 나라의 온실 설치 면적은 1999년말 현재 51,200ha에 이르고 있으며 그 중 유리온실이 363ha로 0.7%, 철골 경질판 온실이 125ha로 0.2%이고, 아연도강관을 사용한 비닐하우스가 50,712ha로 99.1%를 차지하고 있다. 파이프 골조의 비닐하우스는 대부분 아치형의 지붕 모양을 하고 있으며, 바람에는 비교적 강하나 적설에 약한 구조이다. 전국적으로 가장 널리 분포하고 있는 직경 25.4mm, 두께 1.5mm의 파이프를 사용한 폭 6m의 단동 온실의 경우 서까래 간격 60~80cm일 때 안전 적설심은 10~14cm 정도에 불과하다(남 등, 2000). (중략)

• Journal of Bio-Environment Control
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• v.29 no.2
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• pp.196-201
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• 2020

In order to increase the durability of the pipe framed greenhouse, galvanized steel pipes with four corrosion protection treatments were installed in the greenhouse. After 20 years, experiments on surface corrosion and strength change were conducted. Control (untreated) pipes exposed in the atmosphere showed a 1.3% reduction in strength, but little difference from other treatments. The strength of heavy protective coating pipes buried in the ground decreased by 0.6%, showing little change, but untreated pipes decreased by 15.7%. And antirust paint and asphalt coating pipes decreased by 4.2~4.4%. Pipes exposed in the atmosphere did not show severe corrosion in all samples. There was no change in heavy protective coating pipes, and no rust was found in antirust painting pipes either and there was only slight discoloration. Asphalt coating pipes discolored black and some rust was found, and untreated pipes were rusted by 20~30% of the surface. However, untreated pipes buried in the ground were completely rusted, and asphalt coating pipes were rusted by 80~90% of the surface. Antirust painting pipes were rusted by 20~30%, and heavy protective coating pipes did not change almost. The heavy protective coating treatment showed a clear corrosion protection effect even in the parts buried in the ground, and the antirust painting treatment also showed some corrosion protection effect. Therefore, it is judged to be applicable to the field of pipe framed greenhouses.

• Journal of Bio-Environment Control
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• v.6 no.4
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• pp.242-249
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• 1997

Environmental control operations have been considerably contributed to the reduction of labor cost in both plastic film and glass greenhouses since government supported projects were begun. However, some problems are still remaining on the optimal environmental control and excessive operation due to an inflexible software regulating ventilation gear - reducers. The unadjustable software caused the damage of ventilation system, resulting in heat stresses of crops. This study was performed to develop a ventilation software controlling the vent opening level, opening sequence, based on the wind direction, and control interval according to the difference between ambient and set- up temperatures. The software included a beeper system alarming urgent cases, while a manager was remote from the greenhouse. A compatible hardware with the software was also developed by using a low-cost diffused DSP controller.

• Journal of agriculture & life science
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• v.45 no.2
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• pp.125-133
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• 2011

This study was conducted on greenhouses whose side heights had been raised after the columns of 1-2W basic type greenhouses had been cut and welding with the same-sized pipes. When the wind load or snow load affects restructured pipe greenhouse like this, those parts will be structurally unsafe. To examine this, the bending strength of welded columns were measured through four stages and compared with the pipes in their original condition. Results are as follows. In the case of a bending test on welded joints about steel pipes used for greenhouses, satisfactory results couldn't be drawn because sections of both ends and the loading parts couldn't endure loads and sank regardless of loading methods. Partial problems could be solved by inserting inside pipe(steel bar) at the sections and the loading parts, but it was necessary to devise more satisfactory bending test methods. The strength of welded joints wasn't much different compared with original conditions and demonstrated only slight differences according to the sample production conditions. However, significant incompleteness in the welding process was expected to cause a decisive loss in strength. On the assumption that there were no problems in the welding process or with regard to the inclination of sub materials for columns after connection, it was deemed reasonable to assume that the strength of welded pipes was about 84~90% of the strength of the pipes in their original condition. Considering mid- and long-term strength decline following the onset of rust at joints or welding sections, structural changes in the main sub materials that are used for greenhouses at farmhouses have to be avoided to ensure structural safety, unless these changes are inevitable.

• Journal of Bio-Environment Control
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• v.4 no.2
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• pp.232-239
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• 1995

This study was carried out to get required torque data needed to design and develop a roll-up ventilation system in a pipe-constructed plastic film green-house. The results obtained from this study are as follows : 1. The required torques of a roll-up ventilation system in greenhouse are the functions of its length. The torques should multiplied by the conversion coefficients (2.0 in ceiling vent, 1.8 in side vent) in case of application. 2. In constructing pipe-constructed plastic film greenhouse, a shaft pipe is the largest essential element in roll - up shaft weight constitution which have an effect on the required torques. Therefore, the pipe should be light using nonferrous materials like aluminum alloy. 3. A planetary reduction ventilator of differential ring gear type is suitable for a roll-up ventilation system, because it can make high efficient reduction just using the first step shift.