• Journal of Biosystems Engineering
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• v.35 no.6
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• pp.393-400
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• 2010

Uniform and rapid pre-drying of mandarin is important to improve the storage quality. The aim of this study was to suggest the basic design of forced ventilated pre-drying facility for mandarin by thermal flow analysis using computational fluid dynamics software (FLUENT 6.2). Developed CFD simulation model was verified by comparison with experimental data. Airflows and temperature distributions in the five conceptional designs including existing ordinary temperature storage rooms were analyzed and appropriate basic design was determined. Analysis of the effect of arrangement of windows and exhaust fans on thermal flow in facility was carried out for more detailed design. The results of this investigation showed that the predicted airflow velocity by CFD simulation showed a good agreement with the measured value and optimum design condition for simulated forced ventilated pre-drying facility of mandarin has two exhaust fans and two windows on both sidewalls and cover on loaded mandarin.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.6
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• pp.780-785
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• 2006

The composition analysis of various radish (Rapharnus sativus L.) leaves and the effects of drying condition on the quality characteristics of hot-air dried radish leaves were carried out by a response surface methodology. Independent variables put in drying temperature $(X_1)$ and drying time $(X_2)$, dependent variables put in color, calcium, iron, vitamin, etc. In the proximate composition of radish leaves by varieties, there were no significant differences in the ash, protein, lipid, calcium and iron content of samples, but there were significant differences in the vitamins, chlorophyll and color value of samples. The quality characteristics on dried radish leaves by central composite design, it was significant value on the moisture content, chlorophyll and color value according to drying temperature and drying times. But there were no significant differences in the contents of calcium $(31.41{\sim}35.80\;mg/g,\;dry\;base)$ and iron $(0.21{\sim}0.29\;mg/g\;dry\;base)$. The multiplex regression coefficients analysis were calculated with independent variables $(X_1,\;X_2)$ and dependent variables (moisture, chlorophyll, color value). The calculated coefficient correlations for the each samples were $R^2>0.97$. The effects of drying temperature were greater than drying time in the total chlorophyll content changes of radish leaves. Based on the present study, the optimum drying condition for the lowest color changes and effective reduction of moisture of radish leaves were expected to be $5{\sim}6$ hours at $70^{\circ}C$.

• YAKHAK HOEJI
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• v.42 no.2
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• pp.153-158
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• 1998

Calcium hydrogen phosphate was synthesized by reacting calcium chloride and sodium hydrogen phosphate solution in this study. It is well known that the particle size and yield o f calcium hydrogen phosphate produced is greatly affected by the synthetic conditions such as the reactant concentration, reaction temperature, reacting fine, mole ratio and drying temperature, etc. The purpose of this study is to investigate the optimum synthesis condition from the viewpoint of yield and sedimentation volume of the prepared calcium hydrogen phosphate powder according to a randomized complete block design proposed by G.E.P. Box and K.B. Wilson. It was found that the optimum synthetic conditions of calcium hydrogen phosphate were as follows: It was found that optirnum temperature range of reactant solutions was $28-38^{\circ}C$ and $32-42^{\circ}C$ respectively, on the viewpoint of yield and sedimentation volume. The optimum concentration range of reactant solutions was 5.5-10.0% and 6.9-7.4% respectively, on the viewpoint of yield and sedimentation volume. The optimum mole ratio of $CaCl_2$ to $Na_2HPO_4$ was in the range of 1.2-2.0 and the optimum reacting time range was 8.5-11.0 minutes. The optimum drying temperature range was $39-41^{\circ}C$ from the viewpoint of yield, but it was $39-43^{\circ}C$ on the basis of sedimentation volume. Crystallographic analysis to X-ray diffraction patterns of commercially available ecalcium hydrogen phosphate and calcium hydrogen phosphate samples prepared in this study suggested that all samples tested belonged to monoclinic crystal system characteristic of $CaHP0_4{\cdot}2H_20$ crystals.

• Korean Journal of Food Science and Technology
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• v.34 no.5
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• pp.799-804
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• 2002

Optimum conditions of freeze-dried carrots were determined using response surface methodology. Physicochemical and sensory properties of freeze-dried carrot prepared at different plate temperatures and chamber pressures were evaluated. Drying time increased with decreasing plate temperature and chamber pressure. Rehydration ratio decreased inversely with chamber pressure at low plate temperature, but increased proportionally with chamber pressure at high temperature. Density, color, and sensory off-flavor were not affected by the plate temperature and chamber pressure. Sensory color, tenderness, and carrot flavor increased with decreasing plate temperature, but were not affected by chamber pressure. Based on the drying time, rehydration ratio, and sensory attributes, optimum plate temperature and chamber pressure for the preparation of freeze-dried carrot were determined as $43^{\circ}C$ and 700 micronHg, respectively.

• Journal of Sericultural and Entomological Science
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• v.13 no.2
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• pp.155-160
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• 1971

This experiment was carried out to investigate the cocoon reeling condiditions required to technical balance work on the automatic silk reeling machine. The results obtained were as follows. 1) Reasonable reeling velocity with regard to raw silk yield and to reeling efficiency varied according to cocoon reelability. It was observed to be about 150m/min on good reelability cocoon (850m of nonbreaking bave length), about 120m/min on medium reelability cocoon (650m of nonbreaking bave length) and from 90m/min to 120m/min on bad reelability cocoon (500m of nonbreaking bave length) 2) Low temperature drying of cocoon (T$_3$) improved the reelability of cocoon, but increased the reeling accidance with deteriorating the quality of raw silk more than the control(T$_1$) or high temperature drying of cocoon (T$_2$). No significant difference was observed in its raw silk yield and silk by-product with regard to cocoon drying temperature. 3) Incomplete drying of cocoon (T$_3$) improved the reelability of cocoon, but increased the reeling accidance with deteriorating the quality of raw silk more than the control(T$_1$) or over drying of cocoon(T$_2$). No significant difference was observed in its raw silk yield and silk by-product with regard to cocoon drying degree. It was cocoon drying condition of cocoon was the control(T$_1$) or high temperature(T$_2$) rather than low temperature (T$_3$) in cocoon drying process. Control (T$_1$) or over drying of cocoon (T$_2$) was adequate rather than incomplete drying of cocoon (T$_3$) for the improvement of the quality of raw silk on the automatic silk reeling process. 4) It was found that the reasonable cooking condition of cocoon was optimum cooking with 4$0^{\circ}C$ of reeling temperature or incomplete cooking with 45$^{\circ}C$ of the reeling temperature in the automatic silk reeling of the domestic cocoon.

• Applied Chemistry for Engineering
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• v.4 no.3
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• pp.497-504
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• 1993

The effect of DCCA (Drying Control Chemical Additives) on the drying of gel was investigated in order to determine an optimum drying condition of mullite precursor through sol-gel process. Aluminium sec-butoxide was synthesized from aluminium foil and then mullite powders were synthesized from Tetra-ethyl-ortho-silicate (TEOS) and the aluminium sec-butoxide. N, N-dimethyl formamide (DMF), Glycerol, 1, 4-Dioxane, and Oxalic acid were used as DCCA. Mullite powders that were calcined at 200, 900, 1100, and $1250^{\circ}C$ for 2hr were analysed by XRD, TG-DTA, FT-IR, and SEM in order to investigate structural change and characteristics of calcined powders. The results of this work showed that the drying time of gel was reduced to about half in the presence of 0.1mol DMF compared with the absence of DCCA and also calcined powders were obtained without remarkable structural change despite of the addition of DCCA.

• Journal of the East Asian Society of Dietary Life
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• v.21 no.4
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• pp.526-534
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• 2011

Cold air drying was conducted on steamed chestnut-sweet potato to improve its quality, convenience, and preference as snack. Steamed sweet potato was dried from 10 to $25^{\circ}C$ for 48 hours, and moisture contents, colors, texture, and taste were evaluated. The lowest moisture content was 4.53% at $25^{\circ}C$. Lightness decreased while other color values (a, b, and ${\Delta}$E) increased with increasing drying temperature and drying time. Reducing sugar and soluble solid contents ranged from 93.22~190.35 mg/g and 17~60 $^{\circ}Brix$, respectively. The highest hardness of chestnut-sweet potato was 25.13 kgf/$cm^2$, and springiness and cohesiveness were 88.60, and 94.87%, respectively, when dried at $25^{\circ}C$ for 48 hours. Sensory evaluation score was highest at $20^{\circ}C$ for 24 hours. The optimum drying conditions were determined to be $19^{\circ}C$ and 39.5 hours by RSM(response surface methodology).

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.9
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• pp.1314-1320
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• 2011

Vacuum drying was conducted for a steamed pumpkin-sweet potato slab to improve its quality, convenience and preference as snack. Steamed sweet potato was dried from 30 to $60^{\circ}C$ for 12 hr, after which moisture contents, colors, and taste were evaluated. The lowest moisture content was 0.22% upon vacuum drying at $60^{\circ}C$ for 12 hr. Lightness decreased while other color values (a, b and ${\Delta}E$) increased with increasing drying temperature and drying time. Reducing sugar and soluble solid contents ranged from 98.7~268.11 mg/g and $19{\sim}72^{\circ}Brix$, respectively. Sensory score of the sample was the highest when dried at $50^{\circ}C$ for 6 hr. The optimum drying conditions were predicted to be $48.5{\sim}62^{\circ}C$ and 5.1~7.1 hr by response surface methodology.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.5
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• pp.866-871
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• 1997

This study was carried out to determine the effect of osmotic dehydration as pretreatment on the qualities of dried cherry-tomatoes. The weight reduction and solid gain in osmosed cherry-tomato were increased by increasing sugar concentration, immersion temperature and time; among three parameters, the immersion temperature affected more than sugar concentration and immersion time did. The moisture content was decreased as increasing sugar concentration, immersion temperature and time, and it was the lowest at the osmotic conditions of 7$0^{\circ}C$, 60$^{\circ}$Brix and 11hr. To determine the optimum processing condition by RSm, the polynomial optimum models were established. The regression models was significant (p<0.05). It was used contour plots to optimize osmotic dehydration. The optimum condition for osmotic dehydration as pretreatments for drying of cherry-tomatoes were immersion temperature of 47~53$^{\circ}C$, sugar concentration of 39~43$^{\circ}$Brix, and immersion time of 7hr, in which process conditions were 78~86% moisture content, 8.5~10$^{\circ}$Brix sugar content and 80~86% weight reduction.

• Korean Journal of Human Ecology
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• v.7 no.2
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• pp.149-159
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• 1998

This study was carried out to examine the role soy milk in the preparation of Yukwa, possibility of substitution of soy milk to isolated soy protein and the effect of drying condition of Yukwa dough on the quality of Yukwa for the purpose of standardization of Yukwa preparation process. Although isolated soy protein did not make any particular effect on the gelatinization characteristics of waxy rice flour, soy milk lowered peak viscosity to half of waxy rice flour. The optimum moisture content of dried Yukwa dough was about 25%, and it can be reached by drying at $60^{\circ}C$ under atmosphere pressure for $4{\sim}5$ hours. On the basis of the results of morphological observations, mechanical and sensory measurement of hardness, and sensory test of the internal structure, mouthfeel and overall acceptability, soy milk was more desirable than isolated soy protein for the quality improvement of yukwa.