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RISS 인기검색어
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- 저자 : 신동창 ( D. C Shin ) (검색결과 4 건)
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핫박스를 이용한 플라스틱온실 피복재 및 보온재의 열적 성질 측정
소레이멘디옵 ( S. Diop ),이종원 ( J. W. Lee ),나욱호 ( O. H. Na ),신동창 ( D. C. Shin ),이현우 ( H. W. Lee ) 한국농공학회 2012 한국농공학회 학술대회초록집 Vol.2012 No.-
Recent increases in fuel prices have forced growers to apply energy-saving measures in their heated greenhouses. As a result, growers have been forced to consider innovative cover materials and they have been advised to install thermal screens. Materials used as greenhouse covers are not spatially homogeneous that’s why the selection of a covering is crucial for attainment of an optimal controlled environment. Several attempts have been already made to develop measurement procedures applicable under conditions resembling those of greenhouse production on purpose to investigate the U-values of glazing materials by using a hot box. The objective of the present study was to investigate the overall heat transfer coefficient of greenhouse covering materials with or without thermal screens commonly used in the country under external and real conditions by using the hot box method. For this research we designed and built a guarded hot box partially based on ASTM standards C 236-89. The technique used in the present work was inspired by work using guarded hot box (Feuilloley et al., 1996) to investigate the overall heat transfer coefficient of different greenhouse covering materials with thermal screens widely used in the country. The test conditions of eight treatments combined covering materials and thermal screens with and without shelter from the sky radiation were used to determine the overall heat transfer coefficient. The insulation effect of two layers covering material is about 28% comparing to one layer covering material and the coefficient is 2.4 (W·m<sup>-2</sup>·K<sup>-1</sup>)less than one layer. The coefficients obtained under the high wind speed were 6∼14% greater than those under the low wind speed. The decrease of the coefficient of one layer and two layers coverings by shelter was about 20% and 30% respectively. When we measure the overall heat transfer coefficients in a laboratory, it is necessary to establish the measuring system to be able to simulate the sky radiation.
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김태욱 ( T. W. Kim ),유주열 ( J. Y. Yu ),신동창 ( D. C. Shin ),이종원 ( J. W. Lee ),이현우 ( H. W. Lee ) 한국농공학회 2013 한국농공학회 학술대회초록집 Vol.2013 No.-
온실기둥 상승장치는 인상하고자 하는 기둥에 보강대를 설치하고 보강대 하부에 공압구동기를 설치하여 구동하며, 구동시 보강대가 50mm 인상되면 공압구동기가 멈추고 하부의 고정멈춤장치가 보강대를 지지하게 메카니즘을 설계하였다. 고정멈춤장치에 보강대가 지지대면 구동장치는 원위치로 하강한다. 하강시 다음 행정에서 보강대를 밀어 올릴 수 있도록 실린더 로드 보강대를 하강시킨다. 보강대는 기둥이 인상되면 측면으로 전복되는 수평력을 지지하기 위해 보강 띠를 설치하고 보강띠는 지상부에 설치된 텐션너에 의해 지지되도록 설계하였다. 텐션너는 기둥이 인상되면 수동으로 작동하여 보강대 인상시 지속적으로 보강대에 수평력이 유지되도록 하였다. 본 연구에서 개발한 온실 기둥 인상장치의 구동방식은 공압식으로 설계하였다. 유압식은 작동유압이 3,000psi이며 100psi 정도에 작용하는 공압식에 비해 단위면적당 30배정도의 힘을 받을 수 있는 장점이 있어, 하우스 인상시 인상보조지주에 그림 1와 같이 유압장치을 내장 설계하여 기구의 단순성의 단점이 있다. 그러나 유압장치의 유압유니트는 공압유니트에 비해 설치비가 고가이고, 유지관리시 작동유체을 완전히 밀폐하여야 하고 시스템작동시 시스템의 기밀을 유지하여야 하는 문제가 있다. 농업시설물을 인상하는 장치는 이동이 빈번하고 설치장소가 변경되는 점을 고려하면 유지관리의 문제가 발생할 수 있고 작동유의 유출은 농작물에 치명적인 해를 끼칠수 있는 단점이 있다. 따라서 본 연구는 작동장치를(공압실린더)인상보조지주에 내장하지 않고 지주외부에 노출시켜 설계하여 유압장치보다는 부피가 많이 차지하는 단점이 있으나 시스템의 구성단가가 저렴하고 시스템의 유지보수 측면에서 유리한 공압시스템으로 설계하였다.
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실내실험에 의한 온실 피복재 및 보온재의 관류열전달계수 측정
소레이멘디옵 ( S. Diop ),이종원 ( J. W. Lee ),나욱호 ( O. H. Na ),신동창 ( D. C Shin ),이현우 ( H. W. Lee ) 한국농공학회 2013 한국농공학회 학술대회초록집 Vol.2013 No.-
To optimize the heating system, it is necessary to assess the actual energy saving potential of new covering systems as they are introduced into markets. Many studies have been conducted to reduce energy consumption for greenhouse heating and suggest an overall heat transfer coefficient. However, the coefficients suggested vary greatly because the covering material characteristics, climate conditions and greenhouse environments differ. Accordingly, modification of existing testing methods is required because, in most cases, they are insufficient for greenhouse covering materials. As a result, further studies using the hot box method to determine the thermal transmittance of various greenhouse covering materials have been conducted. This study is conducted by producing an indoor experimental apparatus for measuring the overall heat transfer coefficient with which the actual sky temperature can be implemented and measuring greenhouse coverings and thermal screens available in Korea to compare the results with the measured results in the outdoor experiment and to assess their appropriateness. Experiment is carried out for 12 kinds of treatment conditions according to combination of covering materials and thermal screens and whether there is sky thermal radiation or not. The measuring results show that the overall heat transfer coefficient increases almost straightforward proportionally as the difference in temperature for all of test covering treatments increases in case that sky thermal radiation is not implemented. And in case that sky thermal radiation is implemented the overall heat transfer coefficient becomes the highest when the difference in temperature between inside and outside of the hot box is 10℃ and is significantly lowered when the difference in temperature becomes near 20℃ and after that, there is no significant change and the overall heat transfer coefficient maintains almost constant as the difference in temperature becomes higher than 20℃. Even though slight differences between the indoor experiment results and the outdoor experiment results are shown, they are in accord with the range of standard deviation of the indoor experiment results. These results show that it is reasonable to measure the overall heat transfer coefficient of greenhouse covering materials and thermal screens through the indoor experiment.
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