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        • KCI등재

          자연 환기식 온실의 모델 기반 환기 제어를 위한 미기상 환경 예측 모형

          홍세운,이인복 (사) 한국생물환경조절학회 2014 시설원예‧식물공장 Vol.23 No.3

          Modern commercial greenhouse requires the use of advanced climate control system to improve crop productionand to reduce energy consumption. As an alternative to classical sensor-based control method, this paperintroduces a model-based control method that consists of two models: the predictive model and the evaluation model. As a first step, this paper presents straightforward models to predict the effect of natural ventilation in a greenhouseaccording to meteorological factors, such as outdoor air temperature, soil temperature, solar radiation and mean windspeed, and structural factor, opening rate of roof ventilators. A multiple regression analysis was conducted to developthe predictive models on the basis of data obtained by computational fluid dynamics (CFD) simulations. The outputof the models are air temperature drops due to ventilation at 9 sub-volumes in the greenhouse and individual volumetricventilation rate through 6 roof ventilators, and showed a good agreement with the CFD-computed results. Theresulting predictive models have an advantage of ensuring quick and reasonable predictions and thereby can be usedas a part of a real-time model-based control system for a naturally ventilated greenhouse to predict the implicationsof alternative control operation. 본 연구에서는 모델 기반의 온실 환경 제어에 활용될수 있는 미기상 환경 예측 모형을 개발하고자 하였다. 전산유체역학 시뮬레이션을 활용하여 다양한 기상 조건과 온실의 환기 구조에 따른 온실 내부의 미기상 변화와 환기창에서의 환기량 변화를 모의하고, 다중회귀분석을 통해 수치 모형을 제시하였다. 비정상상태의 환기 작용을 모의한 결과, 환기창 개방후 환기 효과가 완전히 나타나기 까지는 3분 ~ 20분 정도의 시간이 소요될 수 있는 것으로 나타났다. 기존의센서 실측에 기반을 둔 대부분의 환경 조절 제어 시스템의 경우에는 측정값에 따른 피드백에 의해 환경 제어가 동작하므로 온실 내부의 기온이 상승한 이후에 환경제어를 시작하게 되지만, 모델 기반의 환경 조절 제어시스템을 도입하면 이러한 3분~20분 정도의 시간을 사전에 고려하여 적정 환경을 제어할 수 있도록 미리 환기창의 조작이 이루어지게 된다. 작은 규모의 온실에서는 이러한 영향이 미비할 수 있지만, 근래에 증가하고있는 대규모 온실들에 대해서는 온실 내부 작물 재배환경의 균일성과 적정성, 안정성을 확보하고 환경 조절의 경제성을 추구할 수 있는 모델 기반의 환경 조절 시스템이 필수적이다. 본 연구에서 제시된 수치 모형들은 외부의 기온과 풍속, 지면 온도, 일사량 등의 기상 환경과 온실의 천창개폐율에 따라 유도되는 자연 환기의 성능을 온실 내미기상 변화와 환기창을 통한 환기량 값으로 제시하고있으며, 전산유체역학 시뮬레이션 결과와 비교하여 각각58% ~ 92%, 76% ~ 93%의 예측력을 보였다. 미기상의변화는 온실을 9개의 세부 영역으로 구분하여 각 영역에서의 기온 하락 정도로 나타내며, 환기량은 지붕에 형성된 6개의 천창에서의 공기 유출입량을 각각 제시하여준다. 환기 작용에 의한 미기상의 변화는 반드시 환기창에서의 환기량에 의해 예측되지는 않으므로 환기량과 환기의 효과를 구분하여 적용하는 것이 중요할 것이다. 이러한 수치 모형들은 모델 기반 환경 제어 시스템에서가상의 환기창 동작에 따른 환기 성능을 예측하는데 활용될 수 있으며, 전산유체역학 시뮬레이션과 같은 매우복잡한 예측 모델이 비해 상당히 간단한 형태로 이루어져 있어 빠른 계산 시간을 보장한다. 이는 실시간 제어의 관점에서는 복잡한 예측 모델들에 비해 실시간 예측과 제어가 가능하다는 큰 장점을 가져다준다. 본 연구를 통해 개발되고 시도된 결과들은 모델 기반의 온실 복합 환경 제어 시스템을 위한 알고리즘을 개발하는데 활용될 것이다. 또한 이러한 활용은 농업에 IT기술을 접목하여 농가의 노동력 부족을 극복하고 생산성향상과 경쟁력 확보를 도모하는 농업 선진화에 기여할것으로 기대된다.

        • KCI등재

          데이터 기반 모델에 의한 온실 내 기온 변화 예측

          홍세운,문애경,리송,이인복,Hong, Se Woon,Moon, Ae Kyung,Li, Song,Lee, In Bok 한국농공학회 2015 한국농공학회논문집 Vol.57 No.3

          Internal air temperature of greenhouse is an important variable that can be influenced by the complex interaction between outside weather and greenhouse inside climate. This paper focuses on a data-based model approach to predict internal air temperature of the greenhouse. External air temperature, solar radiation, wind speed and wind direction were measured next to an experimental greenhouse supported by the Electronics and Telecommunications Research Institute and used as input variables for the model. Internal air temperature was measured at the center of three sections of the greenhouse and used as an output variable. The proposed model consisted of a transfer function including the four input variables and tested the prediction accuracy according to the sampling interval of the input variables, the orders of model polynomials and the time delay variable. As a result, a second-order model was suitable to predict the internal air temperature having the predictable time of 20-30 minutes and average errors of less than ${\pm}1K$. Afterwards mechanistic interpretation was conducted based on the energy balance equation, and it was found that the resulting model was considered physically acceptable and satisfied the physical reality of the heat transfer phenomena in a greenhouse. The proposed data-based model approach is applicable to any input variables and is expected to be useful for predicting complex greenhouse microclimate involving environmental control systems.

        • KCI우수등재

          과수원용 스프레이어의 농약 살포 및 비산 예측을 위한 전산유체해석

          홍세운,김락우,Hong, Se-Woon,Kim, Rack-Woo 한국농공학회 2018 한국농공학회논문집 Vol.60 No.3

          Effective pesticide applications are needed to assure the quality and economic competitiveness of fruit production and lower the risk of spray drift. Experimental studies have shown that better spray coverage and less driftability require an understanding of the transport of spray droplets within turbulent airflows in the orchard and the interaction between droplet dynamics and tree canopies. This study developed a computational fluid dynamics (CFD) model to predict pesticide flows in the orchard and spray drift discharged from an air-assisted orchard sprayer. The model represented the transport of spray droplets as well as droplets captured by tree canopies, which were modeled as a conical porous model and branched tree model. Validation of the CFD model was accomplished by comparing the CFD results with field measurements. Spray depositions inside tree canopies and at off-target locations were in good agreement with the measurements. The resulting data presented that 38.6%~42.3% of the sprayed droplets were delivered to the tree canopies while 13.6%~20.1% were drifted out of the orchard, part of them reached farther than 200 m from the orchard. The study demonstrates that CFD model can be used to evaluate spray application performance and spray drift potential.

        • KCI등재

          BES 기법을 이용한 자연환기식 육계사의 난방에너지 분석

          홍세운,이인복,홍희기,서일환,황현섭,유재인,권경석,하태환,김기성,Hong, S.W.,Lee, I.B.,Hong, H.K.,Seo, I.H.,Hwang, H.S.,Bitog, J.P.,Yoo, J.I.,Kwon, K.S.,Ha, T.H.,Kim, K.S. 한국농공학회 2008 한국농공학회논문집 Vol.50 No.1

          Most of the broiler houses in Korea have experienced problems on controlling the environmental conditions such as suitability, stability and uniformity of rearing condition inside the broiler house. It is very critical which if not properly controlled, would cause serious stress on the chickens. It is therefore urgent to develop optimum designs of naturally ventilated broiler house which is appropriate to the four seasons of Korea. Field experiment for this matter is very difficult to conduct due to the unpredictable and uncontrollable weather condition. In this study, the heating load of a naturally ventilated broiler house was calculated using TRANSYS 15 BES program while internal climate and thermal condition were computed using Fluent 6.2. The computed resulted of the conventional ventilation system (A) and upgraded ventilation system (B) (Seo et al, 2007) were compared with each other for cold season. The results of the Building Energy Simulation(BES) indicated that the system B, the upgraded ventilation system made 8% lower total heating load and 47% lower at only the broiler zone compared to the conventional broiler house. Considering the entire broiler house, the existence of middle ceiling made the heating energy 11% lower required than without middle ceiling. Accordingly, the system B with middle ceiling was found to save heating energy by 20% in average. This study showed that the BES program can be a very powerful to effectively compute the energy loads of agricultural building while the energy load is very close related to ventilation efficiency.

        • KCI등재

          축산 악취의 확산 모델 개발을 위한 현장 실험

          홍세운,이인복,황현섭,서일환,권혁진,유재인,권경석,하태환,김용희,Hong, S.W.,Lee, I.B.,Hwang, H.S.,Seo, I.H.,Kwon, H.J.,Bitog, J.P.,Yoo, J.I.,Kwon, K.S.,Ha, T.H.,Kim, Y.H. 한국농공학회 2008 한국농공학회논문집 Vol.50 No.4

          Odor is one of the major nuisances in the environment. In most countries, odor annoyance from livestock production is an increasing problem in community. In order to reduce the odor inconvenience and establish a good relation between livestock industries and the surrounding communities, many studies, such as diffusion simulations and field experiments, on the odor dispersion and its reduction have been investigated. These studies need to accompany the aerodynamic approach, as a main mechanism of diffusion phenomenon, and computational fluid dynamics(CFD) can be effectively used to study this kind of research. CFD considers both various wind conditions as well as topographical conditions to study aerodynamic phenomenon. Therefore the ultimate objective of the study was to develop an aerodynamic model to predict qualitatively and quantitatively odor diffusion from livestock. In this study, as the first step of this study, various phenomena and factors of odor diffusion from livestock houses were investigated through field experiments in 2007. Later, those data will be also used to verify the CFD accuracy as well as to develop 3-dimensional CFD model.

        • KCI우수등재

          간척지 내 단동형 온실의 풍하중에 대한 구조 안정성 분석

          홍세운,김락우,최원,Hong, Se-Woon,Kim, Rack-Woo,Choi, Won 한국농공학회 2017 한국농공학회논문집 Vol.59 No.4

          Coastal reclamation has created large flat lands, part of which is an attractive site to construct greenhouse complexes for the horticulture industry. Wind environments over these coastal lands are entirely different from those of the inland area, and demand increased structural safety. The objective of this study is to evaluate the structural safety of two single-span greenhouses, peach type and even-span type, under the wind characteristics of coastal reclaimed lands. The wind pressure coefficients acting on the walls and roofs of two greenhouses were measured by wind tunnel experiments, and those acting on the roofs were approximately two times larger than those suggested by the existing design guidelines. Consequently, structural analysis conducted by SAP2000 showed that greenhouse structures designed by the existing guidelines might lead to structural failure under coastal wind conditions because their maximum allowable wind speeds were lower than the design wind speed. Especially, the peach type greenhouse constructed in a reclaimed land could be damaged by approximately 48 % of the design wind speed and needed improvement of structural designs. This study suggested increasing the spacing of rafters with thicker pipes for the peach type greenhouse to enhance economic feasibility of the building under strong wind conditions of reclaimed lands.

        • KCI등재

          축사 환기팬 후류의 풍에너지 평가 및 기류 형상의 전산유체역학 모델링

          홍세운,이인복,서일환,권경석,하태환,황현섭,Hong, Se-Woon,Lee, In-Bok,Seo, Il-Hwan,Kwon, Kyeong-Seok,Ha, Tae-Hwan,Hwang, Hyun-Seob 한국농공학회 2012 한국농공학회논문집 Vol.54 No.5

          The objectives of this paper were to evaluate the wind flow behind the livestock ventilation fan for small-scale wind power generation and to make flow profiles of imaginary ventilation fan for future simulation works. The field experiments using typical 50-inch fan indicated that the wind flow behind the ventilation fan had a good possibility of power generation with its high and steady wind speeds up to a distance of 2 m. The expected electricity yield was almost 101~369 W with a small (0.8 m radius) wind turbine. The decline of ventilation fan performance caused by the obstacle was also not significant with about 4 % from a distance of 2 m. The flow profiles for the computational fluid dynamics (CFD) simulation was created by combining the direction vectors analyzed from tuft visualization test and the flow predicted by the rotating fan modeling. The flow profiles are expected to provide an efficient saving of computational time and cost to design a better wind turbine system in future works.

        • 습식공기정화기의 효율적 운용을 위한 강제환기식 돈사의 환기효율성 연구 (1) 돈사의 환기 분석을 위한 CFD 모델 개발

          홍세운 ( Hong Se Wooon ),이인복 ( Lee In Bok ),서일환 ( Seo Il Hwan ),황현섭 ( Hwang Hyun Sup ),유재인 ( Ru Jae In ),하태환 ( Ha Tae Hwan ),권경석 ( Kwan Hyung Suk ) 한국농공학회 2007 한국농공학회 학술대회초록집 Vol.2007 No.-

          While livestock facilities in Korea have been changed larger and denser, breeding environment has been getting worse and the productivity of domestic animal have been decreased. It would be worse especially In the cold season because of the minimized ventilation rate to save energy cost. Therefore wet air cleaner can be used to enhance the rearing environment by removing noxious gases and dusts. But, it is difficult to analyze the internal air flow and the environmental factors by only field experiment. Therefore, aerodynamic computer simulation was used to upgrade ventilation system including arrangement of the wet air cleaner. To make simulation model accurately and actually, simplified pig models and tracer gas decay method were used. Accuracy of simulation model was enhanced by 4.4 % of errors compared with data of the field experiment. From the verified CFD model, internal ventilation system and its efficiency with wet air cleaner will be analyzed quantitatively as well as qualitatively.

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