• 한국식품저장유통학회지
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• 제16권5호
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• pp.650-655
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• 2009

용량 150 kg의 실험용건조기와 heat pump를 이용하여 건조온도 20, 30, 40 및 $50^{\circ}C$에서 건조실험을 수행하였다. 건조과정에서 함수율, 동할율의 경시적 변화와 건조 전 후의 발아율 및 식미를 측정하여 저온건조과정에 벼의 품질과 적정 건조온도를 구명하였다. 건조온도 20, 30, 40 및 $50^{\circ}C$에서 건조속도는 0.3, 0.6, 0.9 및 1.3%/hr 로 건조온도가 높을수록 건조는 빠르게 진행되었으며, 건조온도 $40^{\circ}C$ 이상은 고온영역, 그 이하는 저온영역으로 구분할 수 있다. 동할율은 건조온도 $20^{\circ}C$에서는 발생하지 않았고 건조온도 30, 40 및 $50^{\circ}C$에서 1.6, 6.8 및 24.2%로 나타나 건조온도가 높을수록 동할 발생이 증가하였다. 따라서, 건조온도 20 및 $30^{\circ}C$는 동할율 기준치에 적합한 안전한 온도영역이며, $50^{\circ}C$는 매우 위험한 온도영역으로 판단된다. 또한, 건조온도 $40^{\circ}C$는 동할율 방지를 위해 템퍼링시간 증대 등 운영방법의 조정이 필요하였다. 건조온도가 높을수록 건조후 발아율은 저하하였으며, 건조온도 20 및 $30^{\circ}C$에서 발아율은 종자용으로 사용가능한 영역이었으며, 건조온도 40 및 $50^{\circ}C$는 최소 영역인 80%에 만족하였다. 식미관능검사에서전반적인(Overall) 품질, 외관(Appearance)의 품질, 맛(Taste)의 품질 및 조직감(Texture)의 품질에서 유의적인 차이가 나타났으며, 종합적으로 판단해볼 때 건조온도 $20^{\circ}C$와 $30^{\circ}C$에서 식미가 높게 나타났으며, 건조온도가 가장 높은 $50^{\circ}C$에서는 상대적으로 낮게 나타났다. 따라서, 품질이 우수한 건조조건은 건조온도 $30^{\circ}C$ 이하, 건조속도 0.6%/hr 이하를 유지하는 것이 적정한 것으로 판단된다.

• Journal of Biosystems Engineering
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• 제13권4호
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• pp.46-55
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• 1988

The objective of this study was to develop a computer measurement and control system which enable it possible to manage the natural air rough rice drying and storage properly and safely. The following contents of work were taken in this study in order to fulfill the above goal: 1) Design and construction of measurement system which can measure the rough rice drying conditions automatically and transfer them to computer system for data processing. 2) Development of a management software which can determine the need of fan operation by the analysis of drying and/or storage conditions. 3) Design and construction of a control system which deliver the computer decision of fan operation and make it on and off. 4) Technical and economical analysis of the computer measurement and control system development by the comparison experiments of the computer management and of the manual.

• 태양에너지
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• 제11권3호
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• pp.21-30
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• 1991

곡물 bin을 이용한 벼의 건조실험을 수행하여 상온통풍건조 시스템과 태양열 건조 시스템의 건조 특성을 비교하여 분석하였다. 태양열 건조의 시뮬레이션 모형에 대한 컴퓨터 프로그램을 개발하였으며 시뮬레이션 모형에 의한 함수율의 예측치는 실측치와 전체적으로 일치하였다. 또한, inverter를 사용하여 벼의 건조 상태에 따라 송풍량을 적절하게 제어하는 송풍량 제어 시스템을 개발하였으며, 개발된 송풍량 제어 시스템을 통하여 에너지 절약 효과를 얻을 수 있었다.

• 한국농공학회지
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• 제17권1호
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• pp.3677-3684
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• 1975

A newly devised dryer with heated air for the farm products, especially suited for high water content materials such as red pepper, Beer ground, each Vegetables, and Low water content materials such as Rough rice was tested for its thermal efficiency and drying mechanism, and the optimum conditions for each sample were established. In order to improve the present rural situation of drying farm products which entirely dependent upon natural solar radiation, a study upon an economic multi-parpose dryer was conducted. A series of drying tests were run first with red pepper which is one of the important cash crop in Korean farm. And successive series of tests were also run with such proaucts as garlic, sweet potatoes, green onion, radish, Beer ground and Rough rice. The results from the above experiment in drying system with heat dryer can be summarized as follows. 1. Drying duration could be shortened by the tempering effect in high water content crop such as red pepper and beer ground. 2. The color changes occured in around 20% water content in red pepper. The degree of color change was heavily affected by high temperature and short drying duration. 3. The drying condition of red pepper was most favourable at the temperature of 85$^{\circ}C$ in early stage and 80$^{\circ}C$ in middle stage and 75$^{\circ}C$ at the final stage, and with the air rate of 0.81㎥/sec and with sample amount of 200kg. 4. The drying condition of Rough rice(I.R.667) was most favourable at the templature of 40$^{\circ}C$ in early stage and 35$^{\circ}C$ in middle stage and final stage and with the air rate of 0.2㎥/sec and with sample amount of 75kg. 5. In order to prevent the color change of red pepper and to assure high efficiency in drying mechanism, it was necessary to lower the temperature as the time passes in drying process. 6. For vege tables, the drying rate were short in early stage and there was also tempering effect. However, for garlics, Constant drying rates through the early and final stages were observed and there were no tempering effects. 7. The drying condition or capability were as follows; Sample drying temp($^{\circ}C$) amount of material(kg) drying time(hr) Red pepper 85 200 9 Garlic 85 150 7 Sweet potato 85 200 6 Green Onion 85 200 4 Carrot 85 200 4 Radish 90 250 4 Rough rice(I.R.667) 35 75 4 Beer ground 90 320 3 Considering the above result of experiments, if this kind of dryers were distributed Korean farm and the optimun process were practiced in rural area, it would certainly help them improving the qualites of their product preventing their undue losses, and thus assuring an increase of Korean farm income and promotion of their living standards.

• 산업식품공학
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• 제13권4호
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• pp.308-313
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• 2009

국내 벼 건조기간의 기상조건에 적합한 열펌프를 설계, 제작하여 기본 성능을 측정하고, 건조온도 20-50${^{\circ}C}$ 범위에서 벼 건조실험을 통하여 건조특성 및 소요에너지를 분석하였다. 열펌프는 건압축 냉동 사이클에서 냉동효과는 173.8 kJ/kg이었으며, 냉매순환량은 49.6 kg/hr이었다. 따라서, 성능계수는 5.5로 표준냉동사이클에서 냉매 R-22의 성능계수 4.0에 비해 높은 값을 나타내었으며, 목표 건조공기의 온도 30${^{\circ}C}$ 및 상대습도 40%에 도달하는 시간은 6분 및 7분으로 만족할 만한 수준이었다. 건조온도와 곡온과의 온도차이는 건조온도 21.9${^{\circ}C}$에서는 약 1.5${^{\circ}C}$, 건조온도 48.7${^{\circ}C}$에서는 약 8.5${^{\circ}C}$로서, 건조실에서 상승한 곡온은 템퍼링실에서 충분한 냉각이 이루어지는 것으로 판단되었다. 건조온도 21.9, 30.7 38.8 및 48.7${^{\circ}C}$에서 건조속도는 0.29, 0.61, 0.85 및 1.25%/hr로 나타나 상용건조기와 유사한 수준이었다. 건조온도 21.9${^{\circ}C}$에서 소요에너지는 325 kJ/kg, 건조온도 30.7, 38.8 및 48.7${^{\circ}C}$에서는 667, 692 및 776 kJ/kg로 나타나 외기조건에 따라 건조소요에너지의 차이가 발생했지만, 화석연료를 사용하는 상용 화력건조기의 벼 건조소요에너지 4,000-5,000 kJ/kg에 비해 평균 86% 절감되는 것으로 나타났다.

• 한국농공학회지
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• 제17권4호
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• pp.3980-3990
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• 1975

This study was carried out to develop a method of grain drying ststem that can be done by forcing the heated-air directly into the grains within the sack. The air duct was pushed into the central position of the grain-deposited sack and the heated-air was forced to flow in the radial direction. The system is referred here as the unit sack drying system. At a first step of this study, an air flow resistance tester was constructed to measure the resistance of air flow to grains in cooperated with some different sack materials, the sack materials, the tested were rice-straw bag, sack of polyethylene film, and jute sack In addition, unit sack drying system was constructed to investigate the drying characteristics of the dryer. on this dryer, two kind of terminal air ducts were attached and tested to examine its effects on uniform drying, and also, aseries of drying test was performed to trace the effect of increasing air flow rate on uniform drying. The results are as follows: 1) Resistance of air flow for each sack material was increased almost proportional to the increasing rate of air flow. Experimental data showed little significant differences of the air flow resistance among the materials. 2) From the comparison with air flow resistance of sack material and that of roughrice, it was indicated that airflow resistance of sack material was much higher than that of rice rough Therefore, in the unit sack drying sysle in which air flow is destined to face the sach material after leaving the grain, it was suggested that air flow would be inuniform to each part of grain within sack because of much higher air flow resistance of sack material than that of grain, and the fact would results inuniform grain drying. 3) Drying test on the unit sack drying system in cooperated with different type of terminal air ducts showed that high speed air is better for uniform drying than in high pressure. with the drying system which was assembled with the air ducts delivering higher speed air, there also involved a problem of significant inuniform drying. Therefore, any means to improve the inuniform drying should be undertaken for practical use. 4) A series of drying test with in creasing air flow rate resulted that increasing air flow rate in the unitsack drying system gave little effect on uniform drying, therefore, it is recommened to change its drying system for drying grain uniformly.

• 한국식품과학회지
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• 제31권3호
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• pp.631-637
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• 1999

떡국용 흰떡의 품질특성 시험의 일환으로 다양한 건조방법별로 흰떡을 제조하여 이화학적 특성을 조사하였다. 숙성시간은 흰떡의 수분함량, 수분흡수율과 고형분 용출량에 크게 영향을 미쳤지만, 국물의 혼탁도는 유의적인 차이가 나타나지 않았다. 저장온도에 따라서는 냉장저장시 수분흡수율과 고형분용출량이 가장 높았으며 냉동저장과 상온저장간에는 유의차가 나타나지 않았다. 마이크로파 처리한 시료가 고형분 용출량 및 국물의 혼탁도에서 가장 낮은 값을 보였으나 수분함량은 가장 높았다. 냉장저장한 시료가 가장 밝은 색도를 나타냈고 냉동저장 시료와 상온저장 시료간에는 유의차가 없었다. 숙성시간이나 건조방법에 따른 명암도의 차이는 없었다. 건조후 조리된 흰떡의 조직감은 숙성시간, 저장온도, 건조방법에 따라 차이를 보였으며, 숙성시간이 긴 것이 조직이 단단하였고 냉장저장 시료가 냉동저장이나 상온에 방치한 것보다 경도가 높았다. 마이크로파와 진공을 병행처리한 시료가 마이크로파 및 마이크로파에 열풍을 병행처리한 시료보다 경도가 높았다. 숙성시간은 흰떡의 관능적 특성에 크게 영향을 미쳤지만, 저장온도에 따라서는 경도, 쫀득성, 기호도에서 유의성이 나타나지 않았다. 건조방법에 따라서는 씹힘성을 제외한 모든 특성치에서 유의적인 차이가 나타났다. 미세구조에서는 마이크로파와 진공을 병행한 건조 방법이 표면을 매끄럽게 하면서 기공이 균일한 다공성 구조를 형성시켰다. 물성학적 특성 및 관능적 기호도 등 종합적인 견지에서 볼 때 진공 및 마이크로파를 병행한 건조 방법이 가장 우수함을 나타내었다.

• Journal of Biosystems Engineering
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• 제34권5호
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• pp.351-357
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• 2009

This study was conducted to verify the simulation model through the drying test, and investigate effect of factors, such as temperature of drying air, airflow rate, and velocity of the airflow, on the drying. The low temperature drying simulation model was developed based on the circulation dry simulation model presented by Keum et al. (1987), and by modifying low temperature thin layer drying model, equilibrium moisture content model, latent heat of vaporization model, and crack ratio prediction model. The heat pump and experimental dryer with a capacity of 150kg were used for the test. The RMSE between the predicted and measured value was 0.27% (drying temperature), 0.15% (crack ratio), and 2.08% (relative humidity), so the relevance of the model was verified. In addition, the effect of drying temperature, airflow rate, and velocity of the airflow on the drying was examined. The experimental results showed that the crack ratio at drying temperature of $25{\sim}40^{\circ}C$ was allowable. Moreover, at below $30^{\circ}C$, variation of the crack ratio was slight, but drying time was delayed. Given these results, the drying temperature of over $30^{\circ}C$ was effective. As the airflow rate increased, required energy dramatically increased. Whereas drying rate slowly increased, so loss of drying efficiency was caused. Considering these results, the dryer needed to be designed and adjusted to lower than $30\;m^3/min{\cdot}ton$. As velocity of the airflow increased, required drying energy increased when the velocity of the airflow was over $5\;m^3$/hr, while crack ratio and drying rate showed little variation.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.957-966
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• 1996

An attempt was made to measure the availability of waste heat, released from the cooling system of a small engine, which can be utilized for grain drying. An engine powered flat-bed rough rice dryer was constructed and the performance of the dryer with available engine-waste heat was analyzed for 10 , 20, 30 and 40 cm rough rice bulk depths with a constant dryer base area of 0.81$m^2$/min. The waste heat was sufficient to increase the drying air temperature 7 to 12$^{\circ}C$ at an air flow rate of 8.8 to 5.7㎥/min, while the average ambient temperature and relative humidity were 24$^{\circ}C$ and 70%. The minimum energy requirement was 3.26 MJ/kg of water removed in drying a 40 cm deep grain bed in 14h. A forty to fifty centimeter deep grained seems to be optimum in order to avoid over-drying in the top layers. On the basis of minimum energy requirement (3.26 MJ/kg ) , an estimation was made that the waste heat harvest from an engine of a power range of 1 to 10.5PS can dry about 0.1 to 1 metric on of rough rice from 23% to 15% m.c. (w.b) in 12 h at an average ambient temperature and relative humidity of $25^{\circ}C$ and 80%, respectively. The engine-waste heated grain dryer can be used in the rural areas of non industrialized countries where electricity is not available.

• Journal of Biosystems Engineering
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• 제23권5호
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• pp.457-464
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• 1998

A drying speed control system using fuzzy logic was developed in order to minimize the damage of rice quality for a large capacity continuous dryer. The performance of the system was tested at two object moisture content of 17% and 25% on a wet basis. For object moisture content of 17% on a wet basis, the final output moisture contents from 20.46%, 20.96%, 18.98% on a wet basis were 17.99%, 17.6% and 17.23% on a wet basis, respectively. For object moisture content of 25% on a wet basis, the final output moisture contents from 28.85%, 26.95%, 28.11%, 27.8% on a wet basis were 25.24%, 24.9%, 25.23% and 25.09% on a wet basis, respectively.