• Journal of Biosystems Engineering
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• v.25 no.2
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• pp.89-96
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• 2000

In this study, experiments were performed for various drying air temperatures, air flow rates tray distance to analyze drying characteristics of batch type tunnel dryer. In comparison of tunnel drying with cabinet drying which is currently used in the farm, the results of drying simulation model of cabinet dryer was used and then the possibility of applying the drying simulation model of cabinet dryer to batch type tunnel dryer was investigated. The results showed that as the drying temperature increased, the drying rte and moisture difference in the direction of air flow increased and as the air flow rate increased, the drying rate increased and moisture differences decreased. In tunnel dryer, drying through bottom of the tray had large effect on drying rate and the effect was more significant when the drying temperature increased. As air flow rate increased, the difference of drying rates between tunnel and cabinet drying increased and drying rate of tunnel of drying was higher. The drying simulation model could estimate moisture content in tunnel more precisely by using modified effective moisture diffusion coefficient for air flow rate.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1999.12a
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• pp.531-538
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• 1999

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.02a
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• pp.382-388
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• 2000

• Journal of Biosystems Engineering
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• v.1 no.1
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• pp.55-55
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• 1976

An experimental work was conducted to develop an optimum operating system of various hay drying systems ; sun-drying with long hay, sun-drying after chopping, sun-drying after crushing, heated air drying after chopping using batch-type dryer and heated air drying after crushing using tunnel-type dryer. Seombody having 60 cm long and initial moisture content of approximately 79 % in wet basis was used for the experiment. The criteria selected for determining the optimum operating condition were the drying performance rate, the production cost and quality of dried matter of each drying systems. The result of this study are summarized as follows : 1. Drying characteristics of leaves of long stem hay, chopped seombody and crushed one were obtained by maintaining the oven temperature at 70 degrees centigrade. The required drying times for various samples to approximately 15% moisture content in wet basis were about 50 min .for leaves ; 160 min. for crushed hay ; 250 min. for chopped hay ; 340min. for ling hay and more than 360 min .for stems. The drying time of crushed hay was required about 50 % of that for the uncrushed long hay. Such a significant difference of drying of time between the leaf and long stem may indicate that an effective drying of seombody may not be achieved unless any kind of special process treatment for the whole hay is undertaken. 2. In each individual drying system, the following conclusions were drawn: a. After 8 days sun-drying on concrete floor under good days with average tempe?rature at $256{\circ}C$ and relative humidity at 55% at 2 P.M., the moisture content of long hay was still above 25 5'~ and the leaf loss during drying caused by wind and rough handling was more than 50 ~G. b. It was possible to dry the chopped seombody by sun-drying down to about 10 % moisture content within 5 days, however, a stock of heat and discolouration phenomena were observed during the drying, which may be due to the increased deposit-density by chopping, resulting in lowering the quality of the dried product. c. Sun-drying for the crushed material by hay-conditioner was required about 4 days to reduce the moisture content to about 10 %, keeping the quality of dried product at good grade. o. The optimum deposit-depth of the chopped seombody in the batch-type dryer used was about 28cm with about 42kg/hr of drying performance rate. However, it was necessary to overturn the materials between the upper and lower layers in order to obtain a good quality of dried product. d. The drying performance rate by the tunnel-type drier was highest among those of drying systems tested, giving the rate of approximately 400kg/day. 3. On reviewing the individual drying system for seombody, it was possible to draw conclusion that the best system was tunnel drying with the crushed seombody as far as the performance rate was concerned. However, the methods gives the highest operational cost. The system for the lowest operational cost with good quality of dried product was the sun-drying with the crushed material. Accordingly, it may be recommended that the system of sun-drying for the crushed seombody may be the most feasible system presently applicable to farm-level operation.

• Journal of Biosystems Engineering
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• v.1 no.1
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• pp.56-63
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• 1976

An experimental work was conducted to develop an optimum operating system of various hay drying systems ; sun-drying with long hay, sun-drying after chopping, sun-drying after crushing, heated air drying after chopping using batch-type dryer and heated air drying after crushing using tunnel-type dryer. Seombody having 60 cm long and initial moisture content of approximately 79 % in wet basis was used for the experiment. The criteria selected for determining the optimum operating condition were the drying performance rate, the production cost and quality of dried matter of each drying systems. The result of this study are summarized as follows : 1. Drying characteristics of leaves of long stem hay, chopped seombody and crushed one were obtained by maintaining the oven temperature at 70 degrees centigrade. The required drying times for various samples to approximately 15% moisture content in wet basis were about 50 min .for leaves ; 160 min. for crushed hay ; 250 min. for chopped hay ; 340min. for ling hay and more than 360 min .for stems. The drying time of crushed hay was required about 50 % of that for the uncrushed long hay. Such a significant difference of drying of time between the leaf and long stem may indicate that an effective drying of seombody may not be achieved unless any kind of special process treatment for the whole hay is undertaken. 2. In each individual drying system, the following conclusions were drawn: a. After 8 days sun-drying on concrete floor under good days with average tempe\ulcornerrature at $256{\circ}C$ and relative humidity at 55% at 2 P.M., the moisture content of long hay was still above 25 5'~ and the leaf loss during drying caused by wind and rough handling was more than 50 ~G. b. It was possible to dry the chopped seombody by sun-drying down to about 10 % moisture content within 5 days, however, a stock of heat and discolouration phenomena were observed during the drying, which may be due to the increased deposit-density by chopping, resulting in lowering the quality of the dried product. c. Sun-drying for the crushed material by hay-conditioner was required about 4 days to reduce the moisture content to about 10 %, keeping the quality of dried product at good grade. o. The optimum deposit-depth of the chopped seombody in the batch-type dryer used was about 28cm with about 42kg/hr of drying performance rate. However, it was necessary to overturn the materials between the upper and lower layers in order to obtain a good quality of dried product. d. The drying performance rate by the tunnel-type drier was highest among those of drying systems tested, giving the rate of approximately 400kg/day. 3. On reviewing the individual drying system for seombody, it was possible to draw conclusion that the best system was tunnel drying with the crushed seombody as far as the performance rate was concerned. However, the methods gives the highest operational cost. The system for the lowest operational cost with good quality of dried product was the sun-drying with the crushed material. Accordingly, it may be recommended that the system of sun-drying for the crushed seombody may be the most feasible system presently applicable to farm-level operation.

• Solar Energy
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• v.11 no.3
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• pp.9-20
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• 1991

Experiments for drying radish were carried out to analyze the drying characteristics and quality evaluation between solar heated-air drying and natural air drying system. Solar heated-air drying system consists of a small fan, a solar air heater and a tunnel dryer. Simulation model for thermal environments of solar collector was developed to investigate the effect of solar radiation and airflow rate on thermal performance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.6
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• pp.427-446
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• 2008

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2006 has been accomplished. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environments. The conclusions are as follows. (1) The research trends of fluid engineering have been surveyed as groups of general fluid flow, fluid machinery and piping, etc. New research topics include micro heat exchanger and siphon cooling device using nano-fluid. Traditional CFD and flow visualization methods were still popular and widely used in research and development. Studies about diffusers and compressors were performed in fluid machinery. Characteristics of flow and heat transfer and piping optimization were studied in piping systems. (2) The papers on heat transfer have been categorized into heat transfer characteristics, heat exchangers, heat pipes, and two-phase heat transfer. The topics on heat transfer characteristics in general include thermal transport in a cryo-chamber, a LCD panel, a dryer, and heat generating electronics. Heat exchangers investigated include pin-tube type, plate type, ventilation air-to-air type, and heat transfer enhancing tubes. The research on a reversible loop heat pipe, the influence of NCG charging mass on heat transport capacity, and the chilling start-up characteristics in a heat pipe were reported. In two-phase heat transfer area, the studies on frost growth, ice slurry formation and liquid spray cooling were presented. The studies on the boiling of R-290 and the application of carbon nanotubes to enhance boiling were noticeable in this research area. (3) Many studies on refrigeration and air conditioning systems were presented on the practical issues of the performance and reliability enhancement. The air conditioning system with multi indoor units caught attention in several research works. The issues on the refrigerant charge and the control algorithm were treated. The systems with alternative refrigerants were also studied. Carbon dioxide, hydrocarbons and their mixtures were considered and the heat transfer correlations were proposed. (4) Due to high oil prices, energy consumption have been attentioned in mechanical building systems. Research works have been reviewed in this field by grouping into the research on heat and cold sources, air conditioning and cleaning research, ventilation and fire research including tunnel ventilation, and piping system research. The papers involve the promotion of efficient or effective use of energy, which helps to save energy and results in reduced environmental pollution and operating cost. (5) Studies on indoor air quality took a great portion in the field of building environments. Various other subjects such as indoor thermal comfort were also investigated through computer simulation, case study, and field experiment. Studies on energy include not only optimization study and economic analysis of building equipments but also usability of renewable energy in geothermal and solar systems.