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

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.51 no.spc1
• /
• pp.224-228
• /
• 2006

The characteristics associated with the Alisma plantago quality and the factors as the proper harvesting time and drying temperature of Alisma plantago were examined from 2004 to 2006 at Sunchon, Southern region. The Alisma plantago cultivars tested were Sunwol and Yongjun. The highest yields of root and good quality, color and luster were obtained when harvested 22 days after first frost date and dried with $35-40^{\circ}C$ of a weeks at the drying oven for Sunwol and Yongjin cultivars. Considering from our results, optimum harvesting time were most likely to be harvesting time of 22 days after first frost date and drying temperature of $35-40^{\circ}C$ of a weeks at the drying oven.

• Clean Technology
• /
• v.17 no.3
• /
• pp.209-214
• /
• 2011

The effects of inlet gas velocity (0.26-0.31 m/s), inlet gas temperature (315-353 K) and the mass ratio (0.1-0.4) of fine polymer (crosslinked poly methyl methacrylate beads) to inert medium particles on the drying rate of fine polymer in a 0.15 m-ID ${\times}$ 1.0 m-high inert medium fluidized bed dryer have been investigated. Crosslinked PMMA beads of 20 ${\mu}m$ (group C) were used as fine polymer, and glass beads of 590 ${\mu}m$ (group B) were used as the inert medium. The drying rate increases with increasing inlet gas temperature and velocity. However, the drying rate decreases slightly as the mass ratio of fine polymer to inert medium particles increases. The particle size distribution of dried fine polymers was mono distribution.

• Journal of the Korean Wood Science and Technology
• /
• v.40 no.1
• /
• pp.44-52
• /
• 2012

This study examined the effects of the drying rate, temperature distribution and vapor pressure on the surface checks occurring during the air circulating oven-drying of hollowed short Japanese larch (Larix Kaemferi C.) round posts treated with coating (CO) and vapor-dam (VD). The hollowed round posts could be dried from the green condition to a moisture content of approximately 8% in 72 to 144 hours. The temperature in the hole was higher than that inside of wood for Control and VD specimens, while VD specimen showed opposite distribution. The vapor pressure inside the wood was higher than that in the hole for the CO and VD specimens during hole drying stage. There were few surface checks found in the specimens but the number increased in order the of CO, VD and Control specimens.

• Korean Chemical Engineering Research
• /
• v.60 no.2
• /
• pp.237-242
• /
• 2022

In this study, a drying method that can effectively remove residual solvent from (+)-dihydromyricetin was developed. Residual acetone concentration was efficiently removed below ICH-specified value (5,000 ppm) by simple rotary evaporation with ethanol pretreatment. In addition, the residual ethanol met the ICH-specified value (5,000 ppm) by simple rotary evaporation through the addition of water, and the residual moisture also met the specified value (<4%) for active pharmaceutical ingredients. At all the drying temperature (35, 45, and 55 ℃), a large amount of the residual solvent was initially removed during the drying, and the drying efficiency increased when increasing the drying temperature. Removal of residual solvent by ethanol pretreatment was shown to be related to high vapor pressure of acetone-ethanol mixture and hydrogen bonding between acetone and ethanol.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.13 no.2
• /
• pp.73-78
• /
• 2003

The influence of calcination temperature on the pore structure of freeze dried silica gel derived from tetraethyl orthosilicate (TEOS) was investigated using $N_2$adsorption and mercury intrusion techniques. Freeze dried material contained not only 4-6 nm sized mesopores and 6-10 $\mu\textrm{m}$ sized macropores, but minor micropores. The change of pore structure due to the increase of calcination temperature was dependant upon the degree of densification.

• Journal of the Korea Institute of Building Construction
• /
• v.16 no.4
• /
• pp.305-311
• /
• 2016

This study examined the long-term inelastic characteristics, including unrestrained shrinkage and creep, of low-heat cement concrete under different ambient curing temperatures. To achieve the designed compressive strength of 42MPa, water-to-binder ratios were selected to be 27.5, 30, and 32.5% for curing temperatures of 5, 20, and $40^{\circ}C$, respectively. Test results showed that the shrinkage strains of concrete mixtures tended to decrease with the decrease in curing temperature because of the delayed evaporation of internal capillary and gel waters. Meanwhile, creep strains were higher in concrete specimens under lower curing temperature due to the occurrence of the transition temperature creep. The design models of KCI provision gave better accuracy in comparison with test results than those of ACI 209, although a correction factor for low-heat cement needs to be established in the KCI provision.

• Journal of the Korean Regional Science Association
• /
• v.40 no.2
• /
• pp.107-130
• /
• 2024

Urban land surface temperature (LST) change is a major environmental factor that affects the thermal comfort, energy consumption, and health of urban residents. Most studies that explored the relationship between LST and urban built-environment form analyzed only midday LST. This study explores the diurnal variation of summertime LST in Seoul using ECOSTRESS data, which observes LST at various times of the day and analyzes whether the LST variation differs by built environment type. Launched in 2018, ECOSTRESS operates in a non-sun-synchronous orbit, observing LST with a high resolution of 70 meters. This study collected data from early morning (6:25) to evening (17:26) from 2019 to 2022 to build time-series LST. Based on greenery, water bodies, and building form data, eight types of Seoul's built environment were derived by hierarchical clustering, and the LST fluctuation characteristics of each cluster were compared. The results showed that the spatial disparity in LST increased after dawn, peaked at noon, and decreased again, highlighting areas with rapid versus stable LST changes. Low-rise and high-rise compact districts experienced fast, high temperature increases and high variability, while low-density apartments experienced moderate LST increases and low variability. These results suggest urban forms that can mitigate rapid daytime heating.

• Korean Journal of Food Science and Technology
• /
• v.40 no.1
• /
• pp.36-41
• /
• 2008

This study was conducted to investigate the effects of combined osmotic dehydration and hot-air drying on the quality of dried apple products. Apple cylinders were steeped in 30% and 50% sucrose solutions at different steeping times. During the osmotic dehydration, as the concentration of the sucrose solution and steeping time increased, weight reduction and water loss increased, and the solid gain showed similar results. Osmotic dehydration in the sucrose solutions was followed by hot-air drying at 50 and $70^{\circ}C$. The experimental data were fitted successfully using the modified Page model. At the drying temperature of $50^{\circ}C$, the drying time increased from 4.15 hr for the control to 5.78 hr and 6.42 hr for the 30 and 50% sucrose solution treatments, respectively. Similar results were shown at the $70^{\circ}C$ drying temperature. The k and n values of the apple cylinders decreased by osmotic dehydration, and the k and n of the apple cylinders steeped in the 50% sucrose solution were lower than those of the samples steeped in the 30% sucrose solution. The qualities of the dried apple products were compared to samples that did not undergo osmotic dehydration. The shrinkage and rehydration capacity of the apple products decreased via osmotic dehydration, and decreased as the concentration of the sucrose solution increased. The compressibility ratios of the apple products to raw apple cylinders increased by osmotic dehydration, and increased as the concentration of sucrose solution increased. The sensory evaluation results for the apple products rehydrated in yoghurt indicate that osmotic dehydration greatly enhances the palatability of apple products in terms of appearance, taste, and texture.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.7
• /
• pp.694-699
• /
• 2008

Considering the severe regulation associated with sludge treatment such as direct landfill and ocean dumping, there is no doubt in that an advanced study for the proper treatment of sludge is urgently needed in near feature. As one of viable method for sludge treatment, fry-drying of sludge by waste oil has been investigated in this study. The fundamental mechanism of this drying method lies in the phenomenon of rapid moisture escape in the sludge pore toward oil media. This is caused by the severe pressure gradient formed by the rapid oil heating between sludge and oil. As part of research effort of fry-drying using waste oil, a series of basic study has been made experimentally to obtain typical drying curves as function of important parameters such as drying temperature, drying time, oil type and geometrical shape of sludge formed. Based on this study, a number of useful conclusion can be drawn as following. The fry-drying method by oil immersion was found quite effective in the removal efficiency of sludge moisture, in general, the moisture content decreases significantly after 10 minutes and the whole moisture content was less than 5% after 14 minutes regardless of the drying temperature. The increase of oil temperature up to 140$^{\circ}C$ favors significantly for the removal of moisture but there was no visible difference above 140$^{\circ}C$. As expected, the decrease of diameter in sludge was efficient in drying due to the increased surface area per unit volume. Further, the effect of oil property by the change of oil type was noted. To be specific, for the case of engine oil the efficiency was found to be remarkably delayed in moisture evaporation compared with that of vegetable oil due to the increased viscosity of engine oil. It produced a result of increasing the evaporation of moisture largely relatively high in the drying temperature over 140$^{\circ}C$ compared with the drying temperature 120$^{\circ}C$ drying temperature as the drying time passed. Accordingly, the drying temperature is considered desirable as keeping over 140$^{\circ}C$ regardless of a sort of used oil.