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류명진,류동기,정선옥,허윤근,허승오,홍순정,성제훈,김학헌 한국농업기계학회 2014 바이오시스템공학 Vol.39 No.1
Purpose: In protected crop production facilities such as greenhouse and plant factory, farmers should be present and/orvisit frequently to the production site for maintaining optimum environmental conditions and better production, which istime and labor consuming. Monitoring of environmental condition is highly important for optimum control of the conditions,and the condition is not uniform within the facility. Objectives of the paper were to investigate spatial and vertical variabilityin ambient environmental variables and to provide useful information for sensing and control of the environments. Methods: Experiments were conducted in a strawberry-growing greenhouse (greenhouse 1) and a cherry tomato-growinggreenhouse (greenhouse 2). Selected ambient environmental variables for experiment in greenhouse 1 were air temperatureand humidity, and in greenhouse 2, they were air temperature, humidity, PPFD (Photosynthetic Photon Flux Density), andCO2 concentration. Results: Considerable spatial, vertical, and temporal variability of the ambient environments wereobserved. In greenhouse 1, overall temperature increased from 12:00 to 14:00 and increased after that, while RH increasedcontinuously during the experiments. Differences between the maximum and minimum temperature and RH values weregreater when one of the side windows were open than those when both of the windows were closed. The location and heightof the maximum and minimum measurements were also different. In greenhouse 2, differences between the maximum andminimum air temperatures at noon and sunset were greater when both windows were open. The maximum PPFD wereobserved at a 3-m height, close to the lighting source, and CO2 concentration in the crop growing regions. Conclusions: Inthis study, spatial, vertical, and temporal variability of ambient crop growing conditions in greenhouses was evaluated. Andalso the variability was affected by operation conditions such as window opening and heating. Results of the study wouldprovide information for optimum monitoring and control of ambient greenhouse environments.
허승오,류명진,류동기,정선옥,허윤근,최진용,Hur, Seung-Oh,Ryu, Myong-Jin,Ryu, Dong-Ki,Chung, Sun-Ok,Huh, Yun-Kun,Choi, Jin-Yong Institute of Agricultural Science 2011 Korean Journal of Agricultural Science Vol.38 No.4
Wireless technology has enabled farmers monitor and control protected production environment more efficiently. Utilization of USN (Ubiquitous Sensor Network) devices also brought benefits due to reduced wiring and central data handling requirements. However, wireless communication loses signal under unfavorable conditions (e.g., blocked signal path, low signal intensity). In this paper, performance of commercial wireless communication devices were evaluated for application to protected crop production. Two different models of wireless communication devices were tested. Sensors used in the study were weather units installed outside and top of a greenhouse (wind velocity and direction, precipitation, temperature and humidity), inside ambient condition units (temperature, humidity, $CO_2$, and light intensity), and irrigation status units (irrigation flow and pressure, and soil water content). Performance of wireless communication was evaluated with and without crop. For a 2.4 GHz device, communication distance was decreased by about 10% when crops were present between the transmitting and receiving antennas installed on the ground, and the best performance was obtained when the antennas were installed 2 m above the crop canopy. When tested in a greenhouse, center of a greenhouse was chosen as the location of receiving antenna. The results would provide information useful for implementation of wireless environment monitoring system for protected crop production using USN devices.
류동기,류명진,정선옥,허승오,홍순정,성제훈,김학헌 한국농업기계학회 2014 바이오시스템공학 Vol.39 No.1
Purpose: Monitoring and control of environmental condition is highly important for optimum control of the conditions,especially in greenhouses and plant factories, and the condition is not uniform within the facility. Objectives of the studywere to investigate variability in soil water content and to provide information useful for better irrigation control. Methods:Experiments were conducted in a strawberry-growing greenhouse (greenhouse 1) and a cherry tomato-growing greenhouse(greenhouse 2) in winter. Soil water content, electrical conductivity (EC), and temperature were measured over the entirearea, at different distances from an irrigation pump, and on ridge and furrow areas. Results: When measured over the entiregreenhouse area, soil water content decreased and temperature and electrical conductivity increased over time frommorning to afternoon after irrigation. Water content decreased by distance from the irrigation pump up to 70 m andincreased after that, and temperature showed an inverse pattern. Soil water contents on the ridge were lower than those onthe furrow, and the differences were 10.2~18.4%, indicating considerable variability. The lowest EC were observed on thefurrow and highest values were observed on the ridge. Soil water contents were less and temperature levels were greater atthe window side than in the center locations. Conclusions: Selection of number and location of soil water content sensorwould be the first step for better water content monitoring and irrigation control. Results of the study would provide basicdata useful for optimum sensor location and control for underground greenhouse environment.
Research Trends for Performance, Safety, and Comfort Evaluation of Agricultural Tractors: A Review
Md. Shaha Nur Kabir,류명진,정선옥,김용주,최창현,홍순정,성제훈 한국농업기계학회 2014 바이오시스템공학 Vol.39 No.1
Background: Significant technological development and changes happened in the tractor industries. Contrariwise, the testprocedures of the major standard development organizations (SDO’s) remained unchanged or with a little modification overthe years, demanding new tractor test standards or improvement of existing ones for tractor performance, safety, andcomfort. Purpose: This study focuses on reviewing the research trends regarding performance, safety and comfortevaluation of agricultural tractors. Based on this review, few recommendations were proposed to revise or improve thecurrent test standards. Review: Tractor power take-off power test using the DC electric dynamometer reduced human errorin the testing process and increased the accuracy of the test results. GPS signals were used to determine acceleration andconverted into torque. High capacity double extended octagonal ring dynamometer has been designed to measure drawbarforces. Numerical optimization methodology has been used to design three-point hitch. Numerous technologies, drivingstrategies, and transmission characteristics are being considered for reducing emissions of gaseous and particulatepollutants. Engine emission control technology standards need to be revised to meet the exhaust regulations for agriculturaltractors. Finite Element Analysis (FEA) program has been used to design Roll-Over Protective Structures (ROPS). Programand methodology has been presented for testing tractor brake systems. Whole-body vibration emission levels have beenfound to be very dependent upon the nature of field operation performed, and the test track techniques requireddevelopment/adaptation to improve their suitability during standardized assessment. Emphasizes should be given toimprove visibility and thermal environment inside the cab for tractor operator. Tractors need to be evaluated underelectromagnetic compatibility test conditions due to large growing of electronic devices. Research trends reviewed in thispaper can be considered for possible revision or improvement of tractor performance, safety, and comfort test standards.
허승오(Seung-Oh Hur),류명진(Myong-Jin Ryu),류동기(Dong-Ki Ryu),정선옥(Sun-Ok Chung),허윤근(Yun-Kun Huh),최진용(Jin-Yong Choi) 충남대학교 농업과학연구소 2011 농업과학연구 Vol.38 No.4
Wireless technology has enabled farmers monitor and control protected production environment more efficiently. Utilization of USN (Ubiquitous Sensor Network) devices also brought benefits due to reduced wiring and central data handling requirements. However, wireless communication loses signal under unfavorable conditions (e.g., blocked signal path, low signal intensity). In this paper, performance of commercial wireless communication devices were evaluated for application to protected crop production. Two different models of wireless communication devices were tested. Sensors used in the study were weather units installed outside and top of a greenhouse (wind velocity and direction, precipitation, temperature and humidity), inside ambient condition units (temperature, humidity, CO2, and light intensity), and irrigation status units (irrigation flow and pressure, and soil water content). Performance of wireless communication was evaluated with and without crop. For a 2.4 GHz device, communication distance was decreased by about 10% when crops were present between the transmitting and receiving antennas installed on the ground, and the best performance was obtained when the antennas were installed 2 m above the crop canopy. When tested in a greenhouse, center of a greenhouse was chosen as the location of receiving antenna. The results would provide information useful for implementation of wireless environment monitoring system for protected crop production using USN devices.