• Journal of Biosystems Engineering
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• 제23권3호
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• pp.229-244
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• 1998

This study was performed to determine proper fan and heater management schemes for natural air drying of rough rice in round steel bin with stirring device under Korean weather conditions. A computer simulation model was developed to predict moisture content changes, energy requirements, and drymatter losses during drying of rough rice by natural air. Drying test was conducted to validate the simulation model using round steel bin of holding capacity of 300ton at Rice Processing Complex in Jincheon. The bin was filled with rough rice every day and mixing by stirring device. Moisture contents, ambient air temperatures, relative humidities, static pressures in plenum chamber in the bin, airflow rates, and electrical and fuel energy were measured. Relative errors of moisture content changes predicted by the simulation model were below 5ft, and relative errors of final moisture content, final grain weight, required energy ranged from 0.9% to 6%. These not levels indicated that the simulation model can satisfactorily predict the performance factors of natural air drying system such as drying rates and energr consumptions comparing error level of 10% to 15% in other drying simulation models generally used in dryer desists. Twelve different fan and heater management schemes were evaluated using the computer simulation model based on three hourly weather data from Suweon for the period of 1952-1994. The best management schemes were selected comparing the drymatter losses, required drying times, required energy consumptions. Operating fan without heating only when ambient relative humidity was below 85% or 90% appeared to be the most effective method of In operation in favorable drying weather. Under adverse drying climates or to reduce required drying time, operating fan continuously, and heating air with $1.5^{\circ}C$ temperature rise only when ambient relative humidity was over 85% appeared to be the most suitable method.

• 한국세라믹학회지
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• 제16권3호
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• pp.155-163
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• 1979

This study was to explore the characteristics of 6 mole% CaO stabilized $ZrO_2$ prepared by wet chemical methods. The results of the experiments were as follows: 1. The powder calcined at 1000$^{\circ}$-110$0^{\circ}C$ was partly agglomerated. The morphology of agglomerate was spherical of 0.5-1$\mu{m}$ in size for Hot Petroleum Drying Method, chain-like of 1-2$\mu{m}$ for Freeze Drying Method, and irreqular of 2-3$\mu{m}$ for Coprecipitation Method. 2. Optimum calcining conditions for powder prepared by wet chemical methods were found: 110$0^{\circ}C$, 2h in air for Hot Petroleum Drying Method and Freeze Drying Method, and 100$0^{\circ}C$, 2h in air for Coprecipitation Method. 3. When specimen was calcined at 1000$^{\circ}$-110$0^{\circ}C$ in air for 2h and then sintered at 1$600^{\circ}C$ in air for 4h, the specimens prepared by wet chemical methods showed a high sintered density (94% of theoretical density) and a low open porosity (<0.8%); however, the sintered density of the specimen prepared by Oxide Wet Mixing Method was 90%. 4. The amount of cubic phase of sintered body prepared by wet chemical methods was observed to be higher than the one prepared by Oxide Wet Mixing Method. 5. It was found that Hot petroleum Drying Method, Freeze Drying Method and Coprecipitation Method were nearly the same in respect of the results of stabilization grade and sintered density of CaO-stabilized $ZrO_2$.

• 한국기계가공학회지
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• 제8권4호
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• pp.61-68
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• 2009

This paper presents the numerical analysis of process of sludge drying to know the characteristics of design parameters and develop the new process plant. Finite volume method and $k-{\varepsilon}$ turbulence model were used to analogy the sludge drying furnace. It has been attempted to perform the disposal of sewage sludge such as simple reclaiming and dumping in sea and incineration. Currently, these methods are restricted by national or international government regulations. The drying process is adopted as an effective method for sewage sludge treatment. However sewage sludge makes it difficult to treat with a large volume at the real drying process plant because of its own complicated physical, chemical, and thermal properties. The final design value of moisture content with 10% of the dried sludge can be obtained through the simulated outputs in this study.

• 한국식생활문화학회지
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• 제38권5호
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• pp.356-364
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• 2023

This study compared the physicochemical properties of soybean curd residue and black soybean curd residue produced by hot air-drying and freeze-drying. Regardless of drying method, the crude protein, crude ash, crude fiber contents, pH, L, a, b color values and water soluble index were higher in soybean curd residue, whereas total polyphenol contents and antioxidant activity were higher in black soybean curd residue. Significant differences in water absorption index, oil absorption capacity and emulsion activity were observed between soybean curd residue and black soybean curd residue in freeze-drying. On the other hand, the emulsion stability was not significant difference in both hot-air drying and freeze-drying. The crude protein and crude fiber contents of soybean curd residue were not significant difference between hot-air drying and freeze-drying. Freeze-drying resulted in higher crude ash contents, pH, water absorption index, water soluble index, oil absorption capacity, emulsion activity and emulsion stability than hot-air drying. Hot-air drying have caused significantly higher water contents, water activity, total polyphenol contents and antioxidant activity in soybean curd residue than freeze-drying. In conclusion, soybean type and drying methods affect the physicochemical and quality characteristics of soybean curd residue, which could be important factors in the manufacture of processed foods.

• 한국식품영양과학회지
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• 제27권3호
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• pp.386-392
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• 1998

Experiments were carried out to establish an effective artificial drying method of Pacific saury (Cololabis seira) to kwamaegi. Raw fish containing 67% moisture were dried up to containing less than 40% moisture by drying for 15 days. The fish lost moisture more rapidly during first 3 days of natural drying than artificial drying. Total lipid content increased from 16.1% to 30.3 and 29.8% by 15 days of natural and artificial drying, respectively. Neutral lipid occupying 91.63% of total lipid increased to 92~94% during 15 days of drying, while content of phospholipid and glycolipid decreased slightly. The values of peroxide and thiobarbituric acid increased up to 6 days of drying and then did not change. Peroxide levels were lower in artifically dried fish than in naturally dried ones.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.242-247
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• 2009

The present study has been conducted to reduce the cold air drying rate. According to the cold air drying method, the quality-excellent product could be made and there would be little change of color, taste and smell. As compared with the hot air drying, the cold air drying equipment has the superior dehumidification in a constant drying zone. However, in a falling drying zone that equipment is not energy-efficient because the drying period could be longer by the dehumidificated.

• Journal of the Korean Wood Science and Technology
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• 제29권4호
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• pp.16-24
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• 2001

함수율은 목재의 효율적인 가공을 위한 기본적인 정보 중에서 가장 중요한 것의 하나이다. 그러나 기존의 열풍식 전건법으로는 수 시간에서 수일이 소요될 정도로 매우 긴 시간이 소요되므로 산업현장에서 적용하기에는 불편하다. 본 연구에서는 가정용 마이크로웨이브 오븐을 응용하여 수 분~수십 분내에 목재 시편의 함수율을 전건법에 의해 측정할 수 있는 기술을 개발하고자 하였다. 국산 3수종에 대하여 마이크로웨이브-전건실험을 수행한 결과 일반 열풍식 전건법에 비하여 전건시간을 1/7~1/10 수준으로 크게 줄일 수 있었고 일반 열풍식 전건법 과 비교하여 전건상태에서 0.1~0.2 g 정도의 편차만 나타내어 함수율 및 전건무게를 신속하고 정확하게 얻을 수 있도록 해주므로써 효율적인 목재건조를 수행하는데 도움이 될 것으로 기대된다.

• 한국연초학회지
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• 제19권2호
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• pp.159-161
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• 1997

A study on the optimal drying condition by a vacuum drying oven was done using shredded tobacco lamina and commercial cigarettes ('This'). Changes in the mass of the experimental material were monitored for about 50 hrs at 6 different temperatures (5$0^{\circ}C$~10$0^{\circ}C$, 1$0^{\circ}C$ stepwise) while continuously operating a vacuum pump. After 30 hrs, small amount of samples from each material were taken sequentially to monitor changes in moisture content using a Karl-Fischer method (Metrohm KF 701 Titrino). Absolute moisture contents calculated from the measurements indicated an ideal data distribution could be obtained by drying at temperatures between 7$0^{\circ}C$~8$0^{\circ}C$. Results from cigarette products which contains humectant and tobacco lamina without it were compared.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 추계 학술논문 발표대회
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• pp.7-8
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• 2016

The use of half PC slab is increasing to shorten construction period. Because the drying shrinkage of topping concrete is restrained by PC slab, the tensile stress is generated at the topping concrete and the cracks can be occurred at the topping concrete due to drying shrinkage. Therefore, it is important to predict the tensile strain of half PC slab due to drying shrinkage to improve the quality of half PC slab. However, there is no studies on prediction of shrinkage behavior of half PC slab yet. Therefore, in this study, half PC slab was made, and the predictability of tensile strain generated at half PC slab due to drying shrinkage was investigated. The step by step method considering creep was used to estimate the tensile strain of half PC slab. In result, good agreement was obtained between the analytical and experimental values.

• 한국약용작물학회지
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• 제22권6호
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• pp.497-503
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• 2014

In order to produce the high quality of dried-ear mushroom, various drying methods such as hot-air drying at $40{\sim}80^{\circ}C$, freeze drying and drying in vinyl house were carried out. Drying hours of hot-air drying, freeze drying and drying in vinyl house were 12.5~21.5, 36.0 and 72.0 hrs, respectively. Vitamin $D_2$ content of sample was the highest as $6.77{\mu}g/g$ DW in drying in vinyl house and then followed by freeze drying as $5.90{\mu}g/g$ DW and hot-air drying as $1.89{\sim}5.01{\mu}g/g$ DW. After dry, external appearance and color of mushrooms applied hot-air drying and drying in vinyl house were better than freeze-dried one. After rehydration, water uptake of sample in drying in vinyl house and hot-air drying at $50{\sim}60^{\circ}C$ were 17.8 and 19.3~21.0 times, respectively. The methods of drying in vinyl house and hot-air drying at $50{\sim}60^{\circ}C$ also led to high hardness, good shape and resilience. As the results of production of dried-ear mushroom with high quality, we suggest that the best method for drying is the drying in vinyl house due to not only high vitamin $D_2$ content, good external appearance and color after drying but also high hardness and good shape after rehydration.