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염성현,강승희,류희룡,윤홍기,이우수,유영지 (사) 한국생물환경조절학회 2023 생물환경조절학회지 Vol.32 No.4
영상 이미지 처리 기법을 활용하여 농업시설에 이용되는 네트 3종의 폐쇄율을 산정하였다. 산정된 네트의 폐쇄율로부터Idel’chik과 Richards와 Robinson이 제안한 관계식을 이용하여 압력 강하를 산정하였으며 풍동시험 결과와 비교하였다. 폐쇄율은 네트 셀의 크기, 내부 끈의 유무 그리고 끈의 두께와개수에 따라 상이하였으며 정면으로 바람이 부는 조건(회전각도 즉, 풍향각도 0°)에서 폐쇄율은 0.22-0.29(전체 회전각도 고려 시 0.22-0.32) 수준으로 나타났다. 약 30%의 폐쇄율(Br ≤ 0.30)을 갖는 네트에 대하여 Idel’chik과 Richards와Robinson의 관계식에 의한 압력 강하가 풍동시험 결과보다다소 높게 예측되었으나 안전한 네트 구조물의 설계를 위해서는 유의미할 것으로 판단되었다. 높은 폐쇄율을 갖는 네트에대한 압력 강하를 예측하기 위해서는 향후 네트 제조 기법(꼬임 정도와 내부 끈의 유무 등)과 바람으로 인한 네트의 변형을고려한 압력 강하 예측 기법에 관한 연구가 필요할 것으로 판단되었다. The blockage rate for three kinds of nets commonly used in agricultural facilities was assessed by using the image acquisition and its relevant processing. By using both empirical relations presented by Idel’chik and Richards and Robinson, and the blockage rate obtained from the image processing, the pressure drop through the nets was predicted and also compared with wind tunnel experiment results. The results of the study showed that the blockage rate of the net was discriminated according to such factors as the magnitude of nets, the existence of inside threads, the thickness and number of threads. In addition, the blockage rate for the incident angle of 0° when the wind blew at the front had the range of 0.22-0.29 (0.22-0.32 when considering whole incident angles from 0° to 45° by 15°). For the nets with the blockage rate of about 30% or below, the prediction by the empirical relations of by Idel’chik and Richards and Robinson showed a little higher pressure drop overall than that of the wind tunnel test, but the use of the empirical relations and the blockage rate could be thought of as providing effectively meaningful guidelines for the safe design of agricultural facilities including nets because the wind tunnel test has been tedious and expensive. Further research and potential application on the prediction technique of the pressure drop, regarding both a subtle deformation by the wind and manufacturing methods with regard to the level of knots and the existence of inside threads, needs to be done for the nets with higher blockage rate.
염성현,강승희,Yum, Sung Hyun,Kang, Seung-Hee 한국농공학회 2013 한국농공학회논문집 Vol.55 No.6
This study was carried out to present the pressure drop for various wind speeds through nine types of screens used in horticultural facilities. The screens have been widely used to prevent harmful insects from being entered into agricultural facilities, to reduce strong wind and to shade a light as well. Whatever the usage of the screens was, it was necessary to have good knowledge of how much the screen caused a pressure drop for wind speeds when analyzing both the inner thermal-flow distribution in the facility and the effect of reducing wind speed by using CFD. Furthermore, as for wind screens, the pressure drop for wind speeds was needed as a design load in evaluating the structural stability of the structures supporting the screens. Therefore, the pressure drop through the screens for wind speeds of 5~30 $m{\cdot}s^{-1}$ at about 5 $m{\cdot}s^{-1}$ interval and inflow angles of $0{\sim}45^{\circ}$ at an interval of $15^{\circ}$ was respectively measured in a subsonic wind tunnel. The relation of the pressure drop for various screens was well fitted as a secondorder polynomial expression.
공기순환 방법이 느타리버섯 재배사 공기 균일도 및 버섯품질에 미치는 영향
염성현,박혜성 한국버섯학회 2022 한국버섯학회지 Vol.20 No.3
Effects of substrate bed interior environments on mushroom qualities were investigated in oyster mushroom cultivation facilities in which either Reversible Air-Circulation Fans (RACF) blowing air in two directions (upwards and downwards) or customary Convection Fans (CF) with air blowing only upwards were operated throughout the cultivation period. Two days before harvest, the deviation ranges of the bed interior temperature and relative humidity in the facility using RACF were in the ranges of 1.0-1.3oC and 7.8-9.0% in the first growing cycle, and within 0.7-1.1oC and 10.0-11.4% in the second cycle. In the facility using CF, the ranges of variation in the indoor environment parameters (5.8-6.4oC and 21.3-23.1% in the first growing cycle, and 3.4-5.7oC and 14.6-18.3% in the second growing cycle) were much enlarged compared to those associated with RACF. These results strongly indicate that RACF significantly enhances air uniformity. Some mushroom qualities differed between growing cycles. For instance RACF in the first cycle gave somewhat better qualities than CF, but some qualities, like pileus diameter and stipe length, were slightly lower than those described for CF in the second cycle when the cultivation substrate weakened. The observation that some qualities worsened under RACF conditions, despite better air uniformity during the growing cycle, revealed the possibility that downward wind may exert a non-negligible negative effect on mushroom growth. Therefore in the future, making wind measurements on the interior and exterior of substrate beds is necessary to obtain insights into their influences on mushroom qualities. The RACF operation manual needs to be edited to convey this necessity.
느타리재배사 정역 제어 대류팬이 공기 균일도에 미치는 영향
염성현,김시환,Yum, Sung Hyun,Kim, Si Hwan 한국생물환경조절학회 2021 생물환경조절학회지 Vol.30 No.4
느타리버섯은 재배사 내부환경에 크게 영향을 받으며 강제 공기순환팬에 의해 공기를 교반하여 내부환경의 균일도를 향상시키고 있다. 본 연구는 느타리버섯 일부 시범 농가에서의 대류팬 작동방법 등 이용 실태를 조사하고, FCU를 가동하지 않은 버섯의 수확이 끝날 무렵이고 폐상 직전인 7.1-10까지 10일 간 느타리 균상재배사에 상향과 하향 등 양방향으로 번갈아 바람을 토출하는 정역 제어 대류팬과 단일 방향인 상향으로만 바람을 토출하는 관행 방식의 유동팬을 설치하여 재배사 내부환경의 균일도를 평가하고자 수행하였다. 조사 농가의 대류팬 작동방법(작동시간과 멈춤시간의 조합 방법)은 대부분 5-15분 작동 후 5-30분 멈춤을 반복적으로 적용하고 있는 것으로 조사되었으며 냉방장치를 가동하지 않은 폐상 무렵의 느타리 균상재배사에 정역 제어 대류팬을 설치하여 내부 환경 균일도를 평가한 결과, 최대 기온 편차는 1.4-1.8℃, 최대 상대습도 편차는 7.8-8.7%로 나타나 최대 기온 편차 3.2-3.7℃, 최대 상대습도 편차 14.0-15.4%를 보인 관행 방식의 유동팬에 비해 내부환경 균일도가 향상된 것으로 나타났다. 20가지의 정역 제어 대류팬 작동방법 중에서는 10-15분간 상향으로 바람을 토출한 후 5-10분 간 멈추고 바람의 방향을 바꾸어 하향으로 10-15분 간 바람을 토출하는 경우가 가장 적은 기온 편차(1.4-1.5℃)를 보였으나 센서의 오차범위 수준에 있어 설정별 차이를 보인다고는 판단할 수 없었다. 향후 버섯의 호흡이 온전히 고려되고 냉방장치가 가동되는 실제 재배기간 중 정역 제어 대류팬이 공기 균일도와 느타리버섯 품질에 미치는 영향을 평가할 필요가 있을 것으로 판단되었으며 재배사 내 공기교반 정도를 확인하기 위한 유동 가시화 연구가 필요할 것으로 판단되었다. It has been known that oyster mushrooms cultivated in facilities with thermal insulation have been strongly affected by inner environments. Forced air-circulation fans exert much direct influence on disturbing air inside the facility so the matter is of particular interest. This study is carried out to investigate the measured levels of air uniformity in a cultivation facility for oyster mushroom in the various cases that reversibly controlled air-circulation fans which drove the flow in the upward and reverse direction by turn and unidirectional fans by which the wind blew upwards only were operated from July 1 to 10. The actual survey for the selection of ongoing operation cases presented that farmers, even though there were some discrepancies, have made use of fans in a way that it paused for 5-30min after running for 5-15min by turn. The level of air uniformity in the case of adopting reversible fans revealed a slight difference of 1.4-1.8℃ (Temp.) and 7.8-8.7% (R.H.) under the condition of not using a cooler during the investigation period. By contrast, unidirectional fans showed a noticeable difference of 3.2-3.7℃ and 14.0-15.4%, which meant that air uniformity driven by reversible fans much more increased compared to that for unidirectional fans. Among the twenty operational applications considered for reversible fans, the circumstance that the wind blew upwards for 10-15min and ceased for 5-10min and blew again in the reverse direction for 10-15min in succession gave minor improvements at the level of air uniformity, but at present there was somewhat difficult to make decision on which cases were optimally best. It seems necessary that the effects of reversible fans on air uniformity as well as qualities of oyster mushrooms have to be appraised in the cultivation period and the flow visualization needs to be done to ascertain the performance of air mixture.
단측파대 상향변환기와 이미지제거 혼합기를 이용한 자기동조회로의 구현
염성현,김태영,김태현,박범준,Yeom, Seong-Hyeon,Kim, Tae-Young,Kim, Tae-Hyun,Park, Boem-June 한국군사과학기술학회 2010 한국군사과학기술학회지 Vol.13 No.6
In this paper, we designed self-frequency synchronizing circuit using image rejection mixer(IRM) and single-sideband(SSB) up-converter which can effectively eliminate the image frequencies occurred in multi-channel super-heterodyne receivers and help us to match inter-channel phase. Also the self-frequency synchronizing circuit simplifies system because there need no extra devices for making intermediate frequency(IF) by creating the local signal within several nanoseconds by means of generating the same frequency of IF signal and modulating radio frequency(RF) signal. We adopt the limiting amplifier for the purpose of protecting the circuit from spurious signals which come from the front end side having wide instantaneous bandwidth characteristics and constantly injecting same level into the input local signal of IRM. The IRM we fabricated has image rejection ratio of 27dB, which is good over 7dB for foreign company's. Also, the SSB up-converter we fabricated has 1dB compression point of 18dBm, which is good over 16dB for foreign company's. And the size is compact about one-forth.
염성현(Sung Hyun Yum),김승희(Seoung Hee Kim),이상봉(Sang Bong Lee),김민영(Min Young Kim),김철수(Chul Soo Kim) (사)한국생물환경조절학회 2010 시설원예‧식물공장 Vol.19 No.2
2007년 4월 이전까지 10~15년 동안 규격시설로 운영되어 오던 농가지도형 단동하우스에서의 보강지주 설치효과를 분석하였다. 이전의 연구로 적설하중에 대한 수식 계산을 통해 보강지주 설치 단동하우스의 추가 적설심이 제시된 바 있으나 모델이 농가지도형 단동하우스 규격과 상이해 연구 결과를 농가지도형 단동하우스에 그대로 적용하기에 무리가 따랐다. 본 연구에서는 농가지도형 단동하우스를 3차원 강뼈대 구조물로 모델링 하여 보강지주 설치 효과를 분석하였으며 재하시험을 통해 해석결과를 검증하였다. 구조해석 결과, 단동 하우스에 보강지주 설치 시 안전적설심은 오히려 줄어드는 것으로 나타났는데 파이프 체결 부에서의 집중하 중으로 지붕도리에 큰 응력이 걸리기 때문으로 보강지주 설치 시에는 지붕도리의 규격도 함께 강화되어야 할 것으로 판단되었다. 지붕도리를 강화하고 보강지주를 3~4m 간격으로 설치할 경우, 안전적설심은 기본 모델에서 보다 2배 이상 높아지는 것으로 나타났다. 보강지주 규격별 농가지도형 단동하우스 5종의 안전적 설심을 제시하였다. This study was implemented to clarify the effect of a supplementary pole on the increment of safety snow-depth for the single-span plastic greenhouses which had been run as standardized facilities for 10 to 15 years till April, 2007. In the previous work, some of the basic ideas of the use of a temporary pole were discussed, but application was restricted to both 2-D and the cases which took rafter’s specifications into no consideration, and there was also much less experimental information available. So, by modeling the house as the 3-D frame structure, the present study attempted to provide a comprehensive review of the pole’s effect through structural analyses as well as measurements. Structural analyses abnormally revealed that the pole regardless of its interval had a negative effect on the structural stability. The results was certainly inconsistent with practical experience and hence implied a necessity of reinforcing the roof purlin. Accordingly, with the purlin being sufficiently reinforced, the plastic greenhouse with the pole’s interval of 3~4 m had two times safety snow-depth more than that of the plastic greenhouse without the pole. And the safety snow-depth of five types of the single-span plastic greenhouses according to the pole’s intervals was presented.
ANSYS와 CFX를 이용한 방풍벽의 구조 안전성 분석
염성현(Sung Hyun Yum),김철수(Chul Soo Kim),최영돈(Young Don Choi) (사)한국생물환경조절학회 2006 시설원예‧식물공장 Vol.15 No.2
대립계 포도 비가림하우스에 부착된 일체형 방풍벽과 노지에 설치된 분리형 방풍벽의 구조 안전성을 설계풍속 30.9mㆍS¹와 50mㆍS¹ 조건에서 각각 분석하였다. 비닐하우스 부착형 방풍벽의 경우, 방풍벽을 설치했을 때 방풍벽의 경사각이 측면부의 유동분포에 미미한 변화를 주어 측면부가 받는 풍압면적이 다소 감소하는 것으로 나타났으나 큰 차이를 보이지는 않았다. 그러나 구조강도 측면에서는 방풍벽 설치를 위한 부가적인 파이프 투입 효과로 약 11% 정도 구조 안전성이 향상되는 것으로 분석되었다. 주기둥 간격이 3m인 분리형 방풍벽의 경우, 대형 태풍수준인 50mㆍS¹에서 구조적으로 불안정한 것으로 나타났으며 분리형 방풍벽의 이론적 고찰 결과와 해석 결과와는 큰 차이를 보여 3차원으로 구성된 구조물의 2차원 모델 시 그 정확성에 한계가 있음을 알 수 있었다. 추후 분리형 방풍벽의 효용성을 증대하기 위하여 최적 파이프 규격 설정에 관한 세부적인 연구가 필요할 것으로 판단되며 비닐하우스 부착형 방풍벽의 경우, 태풍으로 인한 비닐하우스 피해 발생 시 정밀한 피해실태 조사를 통하여 분석 결과의 정확성을 향상시킬 수 있는 구조 안전성분석 기법 개발에 관한 연구가 필요한 것으로 판단되었다. This study was carried out to evaluate the structural safety for both the attached wind-protect-ing wall in greenhouse and the detached one installed outside. Regarding the attached wind-protecting wall in greenhouse, the analysis was conducted by doing a fluid-structure coupled field analysis using both CFX-5.7 and ANSYS 8.1 and also under the design condition of an instantaneous maximum wind velocity of 30.9mㆍs¹. Three kinds of the width ranged from 30 to 90㎝ were considered in this study. With regard to the detached wind-protecting wall, the structural safety was analyzed under the pressure difference of 1,117 Pa which corresponded to a wind velocity of 50mㆍS¹ and the analytical results were also compared with theoretical ones. The result showed that there was little difference in the distribution of velocity overall and total pressure on the lateral side according to the width of the attached wind-protecting wall, but greenhouse with wind-protecting widths of 30 to 60㎝ has been reinforced to the extent of about 11% when compared with the case of being without the wall. The result also showed that the detached wind-protecting wall with a main-column interval of 3m was not stable so that it was necessary for the detached wind-protecting wall to be adequately reinforced to secure structural stability. Finally, there was great difference between analytical results and theoretical studies. The difference meant that there was some possibility of including errors when a theoretical study was done in three dimensional structure.
대립계 포도 천창개폐형 비가림하우스의 최적 파이프 규격
염성현(Sung Hyun Yum),윤남구(Nam Gyu Yun),김경원(Gyeong Won Kim),이성현(Sung Hyoun Lee),조용호(Yong Ho Cho),박서준(Seo Jun Park),박문균(Mun Kyun Park) (사)한국생물환경조절학회 2007 생물환경조절학회지 Vol.16 No.4
본 연구는 기존 비닐하우스 아연도 강관을 사용한 하우스 폭 3.6m와 5m 천창개폐형 대립계 포도 비가림하우스에 대한 구조적 안전성을 검토하고, 인장강도 400Nㆍ㎜?²(SGH400 등) 이상의 파이프를 사용하는 조건에서 하우스 폭 5m인 천창개폐형 대립계 포도 비가림하우스에 대하여 구조적으로 안전한 최적 파이프 규격을 제시하고자 수행하였다. 주기둥 3m×서까래 60 ㎝인 천창개폐형 3.6m 비가림하우스의 경우, 적설심 35㎝에서는 구조적으로 안전한 것으로 분석되었으나 측면 및 전후면 풍속 35mㆍs?¹에서는 불안전한 것으로 나타났으며, 동일 주기둥과 서까래 간격을 갖는 천창개페형 5m 비가림하우스의 경우에는 적설심 35와 풍속 35mㆍs?¹에서 모두 불안전하여 구조보강이 필요한 것으로 분석되었다. 그리고 동일 주기둥과 서까래 간격을 가지나 인장강도 400Nㆍ㎜?² 이상을 갖는 파이프를 사용하는 조건에서 천창개폐형 5m 비가림하우스의 최적 파이프 규격은 지붕높이 1.6m(아치형)와 지붕높이 1.8(복숭아형)에 대하여 동일하게 두 경우로 규격화할 수 있었다. 즉, 안전풍속 35mㆍs?¹와 안전적 설심 40㎝에서 구조적으로 안전한 서까래 규격은 Ф31.8×1.5t@600이었으며, 안전풍속 30mㆍs?¹와 ss 안전적설심 35㎝에서는 서까래 Ф25.4×1.5t@600인 것으로 분석되었다. 덕면으로부터 곡부보까지의 높이는 안전적설심보다는 안전풍속에 직접적인 영향을 미치는 것으로 분석되었으며, 처마를 높임에 따라 측면풍속에 대해서는 방풍벽파이프(측벽서까래)를, 전후면 풍속에 대해서는 마구리기둥의 규격을 강화하여야 하는 것으로 분석되었다. This study was carried out to: (1) analyze structural stability of representative rainsheltering greenhouses for large-grain grapevine cultivation with widths of 3.6 and 5 m in case of using the existing pipe for agriculture; (2) present the optimum specification of pipes in the greenhouse with a width of 5 m under the condition of using the pipe of which ultimate strength has been above 400 Nㆍ㎜?²; (3) evaluate stability and also present the optimum specification of pipes as eaves height was augmented. The above analyses were done for greenhouses with roof vents and also with a main-column interval of 3 m and a rafter interval of 60㎝ First, the existing 3.6m greenhouse with a rafter of Ф25.4 × 1.5 t@600 was stable for a snow-depth of 35 ㎝ but unstable for a wind velocity of 35mㆍs?¹, Meanwhile the existing 5 m greenhouse with the same rafter was not stable for a wind velocity of 335 mㆍs?¹ as well as a snow-depth of 35㎝. This meant that existing greenhouses had to be reinforced to secure stability. Second, the specification of pipes, especially rafter, could be classified as two cases. One had a structural stability at a safe wind velocity of 35 mㆍs?¹ and a safe snow-depth of 40㎝ for which stability the rafter had to be Ф31.8 × 1.5 t@600, and the other had a stability at 30 mㆍs?¹-35㎝ at the specification of rafter Ф25.4 × 1.5 t@600. Finally, eaves height had a significant effect on safe wind velocity. But it had little influence on safe snow-depth. The results showed that the specification of side-wall pipes had to be reinforced for the safe side velocity according to the increment of eaves height and similarly the specification of fore?end post for the safe fore-end velocity.