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Supplemental lighting sources in greenhouses are accompanied by generation of considerable amounts of heat. However, the engineering methods regarding this contribution to greenhouse heating are rarely recognized. This study was conducted to evaluate the experimental and theoretical heat gains from supplemental lighting and their contributions to greenhouse heating. The experimental greenhouse had glass covers and 100 m 2 floor area, and 21 high pressure sodium lamps of 250 W were used as the light source. The greenhouse operated with thermal screens at night in winter and spring. The heat gain from lighting for 5 h a day was evaluated to be maximum 91.3 MJ, and the effective contributions of lighting to heating were evaluated to be between 12.8% and 72.2%.

Purpose: To present a flexible and accurate autonomous solution for creating any desired row spacing value between the hydroponic gullies in multilayer growing units, and evaluate the capabilities and performance of the relevant automated system through the use of virtual prototyping technique. Methods: To build the virtual prototype of the system, CAD models of its different parts, including an autonomous vehicle and the mechanical mechanisms embedded in the multilayer growing unit, were developed and imported into the RecurDyn simulation software. In order to implement the automated row spacing operation, three spacing modes with different loading cycles and working steps were defined, and the operation of the system was simulated to obtain the target row spacing values specified for each of these modes. Results: Motion profiles related to the horizontal displacement of: 1) the lower and upper sliding bars installed in the cultivation layers, and 2) the hydroponic gullies, during the simulation of the system operation, were generated and analyzed. No deviation from the specified target spacing values was observed at the end of simulations for all spacing modes. Conclusions: The results of the motion analysis obtained by simulating the system operation confirm the effectiveness of the control scheme proposed for automated row spacing of gullies. It was also found that proper sequencing of the loading cycles and the precision of the working strokes of the upper bars are the critical factors for establishing a certain row spacing value. Based on the simulation results, precise control of the back and forth motions of the upper bars is highly necessary for sound operation of the real system.

Dept. of Biosystems Engineering, Seoul National University, Seoul, 151-921, Republic of Korea Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, 151-921, Republic of Korea Div. Of Horticulture Industrial Research, Gyeonggido Agricultural Research & Extension Services, Hwaseong, Gyeonggi, 445-784, Republic of Korea Received: November 4th, 2013; Revised: November 18th, 2013; Accepted: January 14th, 2014 Purpose: The modern IT can give enormous impacts on the agricultural production and consumption. However, farmer’s ability to use IT devices has been known as one of the critical factors on success of IT in agriculture. This survey study was performed to evaluate the informatization status of farmers and to draw a strategy to develop and distribute a ubiquitous agricultural information system. Methods: A survey questionnaire with 19 questions on the degree of IT devices such as computers and smartphones and their utilization were developed. The survey was questioned 3 groups of farmers in Gyounggi Province and analyzed statistically by the χ2 test. Results: The order of IT devices distribution were computers, smartphones, smart TVs and tablet PCs in all groups. The ratios of ownerships of the devices are 97.7, 78.6%, 31.4%, 17.8% respectively. The active farmers in this survey showed higher informatization level than that of native and the general farmers. Conclusions: The ubiquitous agricultural information system was judged to be developed for the computer because spread and use of it exceeds the other devices. Also, the information system based on the smartphone could be a complementary way if the rapid of the smartphones continues and proper education on use of the phone is provided.

Dept. of Biosystems Engineering, Seoul National University, Seoul, 151-921, Republic of Korea Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, 151-921, Republic of Korea Dept. of Agricultural Engineering, National Academy of Agricultural Science, Rural Development Administration. Suwon, Korea Dept. Of Organic Agriculture, National Academy of Agricultural Science, Rural Development Administration, Suwon, Gyeonggi, 441-707, Republic of Korea Received: November 20th, 2013; Revised: January 25th, 2013; Accepted: February 19th, 2014 Purpose: This research was conducted to evaluate feasibility of a crank-type walking cultivators for weeding in furrowed upland. Methods: A walking cultivator developed by RDA was selected and evaluated with its working speed (S), cultivation depth (CD) and weeding performance (WP). The evaluation was performed in upland field on July and August, 2012. Also kinematic analysis of the machine was performed to draw out design improvements. Results: S in flat, uphill and downhill were about 0.11 m s-1, 0.11 m s-1, and 0.13 m s-1 respectively. It was found that S had a low relevance with user conditions. The CD was 35 ~ 40 mm which was satisfied with the RDA guide for weeding machine. A wide variation was observed in values of WP depending on the growth stages of weeds and field conditions. The cultivator showed low performance in eliminating the well-grown weeds. Kinematic simulation revealed that high forward speed caused a high ratio of un-weeded area. Conclusions: The weeding performance of the cultivator was satisfactory for weeds in early growth stage but it showed difficulties in handling on up-slope and in entering up-land. Specifically, the weight of the cultivator was judged as overweight for female workers. The crank-hoe type cultivator was judged as unsuitable for small walking type machine due to weight of the four-bar linkage system. Kinematic analysis revealed that the ratio of crank speed to the ground speed must be 850 rpm s m-1 (255 rpm based on 0.3 m s-1) or greater to avoid uncultivated area. Selection of forward speed is a decisive factor in designing the weeding cultivator.

The exhaust gas from combustion has been extensively used for greenhouse CO 2 fertilization. However, its toxic gases and thermal energy would generally limit the proper applicability. The aim of this study is to develop a technology to supply toxic gas-free CO 2 and to recover exhaust gas thermal energy. A combustion-type CO 2 generator was manufactured and connected to a heat pump system for greenhouse heating and cooling. Control algorithm for effective operation of the system was also developed and implemented. Greenhouse operation was run at the conditions under which values for CO 2 concentration and indoor temperature were maintained at 1200–1300 ppm and 25–27 °C, respectively. Technical performance of the system was evaluated in cold, moderate and hot seasons.

Heterogeneous sensor networks have been developed and implemented for agricultural purposes. Although they have shown adequate level of performance during individual applications, it is generally difficult to integrate them. In order to increase their inter-operability, it is important to follow a standard. The objective of this study is to develop a middleware layer supporting Sensor Observation Service (SOS) standard of Open Geospatial Consortium. An embedded system, integrated on a simple weather station with the ability to measure 6 meteorological parameters, was developed. The embedded system implemented three core operations of SOS – GetCapabilities, DescribeSensor, GetObservation – using the web service. The serviced data could either be an observation or description of the sensor system. In order to make SOS operate on an embedded system, various implementation techniques were used. As a result, the responses were well-formed and there was no syntax error. The response time was just 3.44 sec when 500 observations were delivered from two files. It seldom affected measurement process. In addition, the only thing to add new sensors was to update an ObservationCache class and template files. Therefore, the middleware layer was flexible to be applied on other sensor networks.

If a greenhouse in the temperate and subtropical regions is maintained in a closed condition, the indoor temperature commonly exceeds that required for optimal plant growth, even in the cold season. This study considered this excess energy as surplus thermal energy (STE), which can be recovered, stored and used when heating is necessary. To use the STE economically and effectively, the amount of STE must be estimated before designing a utilization system. Therefore, this study proposed an STE model using energy balance equations for the three steps of the STE generation process. The coefficients in the model were determined by the results of previous research and experiments using the test greenhouse. The proposed STE model produced monthly errors of 17.9%, 10.4% and 7.4% for December, January and February, respectively. Furthermore, the effects of the coefficients on the model accuracy were revealed by the estimation error assessment and linear regression analysis through fixing dynamic coefficients. A sensitivity analysis of the model coefficients indicated that the coefficients have to be determined carefully. This study also provides effective ways to increase the amount of STE.