• 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.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.6
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• pp.462-468
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• 1999

Room temperature vulcanizing (RTV) silicone rubber has been widely used to coat porcelain insulators to render water repellency to prevent formation of water film on the surface and thus to suppress the leakage current and consequently flashover. However, the electrical property and the hydrophobicity of RTV silicone rubber coating under outdoor condition may be influenced by many environmental factors. In this studyvarious treatments, such as salt-fog, salt water immerging and UV irradiation were applied to the samples to investigate the change of the electrical property and hydrophobicity. As a result the leakage current increased and contact angle decreased asthe degradation time is longer. But the degraded RTV silicone rubber has recovered its hydrophobicity during the drying time in ambient condition because LMW(Low Molecular Weight) silicone fluid diffused from the bulk to the surface.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.11a
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• pp.87-90
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• 2006

This study investigates the temperature history of slab mock-up specimens for hot weather concreting applying various surface insulating methods, in order to improve concrete quality at hot weather condition. Test showed that the use of insulating blanket or a bubble sheet on upper section of slab prevented from abrupt increase of temperature and vaporization of moisture during early curing at hot weather circumstance. In addition, it secured higher strength at early age. Therefore it is concluded that concrete construction insulating with the bubble sheet will reduce the plastic and drying shrinkage as well as improve strength at early age, thus securing concrete duality.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.4
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• pp.49-55
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• 2011

Recently, various efforts to make more speedy and precision machine tool to improve productivity and also various efforts to solve environmental problem are going on, so that dry cutting in manufacturing industry, which needs environmental conscious design and development of manufacturing technique, is becoming a very important assignment to solve. Because dry cutting does not use cutting fluid, we need other methods that can be used instead of cutting fluid, which does cooling, lubricating, chip washing, and anti-corrosion. Especially, because turning is a continuous work, the consideration of tool life and surface roughness due to continuous heat and poor lubrication is important. The purposes of this paper are the consideration of how well the compressed air can work instead of cutting fluid, and also the development of the method to select the optimum machining condition by the minimum numbers of experiments through the Taguchi method.

• Magazine of the Korea Concrete Institute
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• v.9 no.2
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• pp.153-161
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• 1997

In the concrete st~uctures exposed to the environmental condition, the water movement is occurred by thc moisture difilsion, and the rnoisturrt distribution in concwt.c is nonunifhrm. Such a non-unif'orm moisture distribution causes tht. diflbrent.ia1 drying shrinkage in concrete structures. From this typc. of' dif'fercntial drying shrinkagr' tensiit-1 stress is occurred in exposure surface of concrete structures. and may result in crack formation. This residual stress is significantly affected by the creep of concrete, and the differential creep is also occurred at the cross section of concrete structures due to moisture difference at each locations. In this study, based on the moisture diffusion theory, a finite element program which is capable of simulating the moisture distribution in concrete was developed. And the analysis method for the differential drying shrinkage was suggested, in which the differential creep was considered. The differential drying shrinkage strain was also measured at various positions of concrete. Finally the validity of analysis method was proved by comparing test results with analytical results.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.125-126
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• 2021

In order to improve the housing culture, construction changes for the utilization of diverse and multifunctional spaces are appearing in response to the increasing diverse needs of consumers. Cellular Light-weight Concrete (CLC) is being developed for use in fire-resistant heat-insulating walls and non-bearing walls. However, manufacturing non-uniformity has become a problem as a drawback due to the use of foamed bubbles and normal temperature curing, and additional research is required. Therefore, in order to suppress cracks due to drying shrinkage, silica sand is mixed with CLC to try to understand its characteristics. In the experiment, the compressive strength from 7 to 28 days of age was measured via a constant temperature and humidity chamber, and the drying shrinkage was analyzed according to each condition using a strain gauge. The compressive strength of matrix tends to decrease as the substitution rate of silica sand increases. This is judged by the result derived from the fact that the specific surface area of silica sand is smaller than that of slag. Based on KS F 2701 (ALC block), the compressive strength of 0.6 products is 4.9 MPa or more as a guide, so the maximum replacement rate of silica sand that satisfies this can be seen at 60%. Looking at the change in drying shrinkage for just 7 days, the shrinkage due to temperature change and drying is 0.7 mm, and the possibility of cracking due to shrinkage can be seen, and it seems that continuous improvement and supplementation are needed in the future.

• Journal of the Korean Ceramic Society
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• v.30 no.9
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• pp.775-783
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• 1993

TiO2-SiO2 system anti-reflective(AR) film was prepared to decrease reflectance on the glass surface. The experiments were carried out as fellow, 1) preparation & hydrolysis of TiO2-SiO2 system sols. 2) glass dipping, and 3) drying & heat treatment. We investigated the refractive index and thickness of film with viscosity, zeta-potential of sol, sol concentration, withdrawal speed, drying and heat treatment condition. As a result, we prepared good qualitative Quarter-Half-Quarter type anti-reflective film that had minimum, 0.02% and average reflectance, 0.087% in the visible region.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.270-273
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• 2000

For the well-preparation of the superconducting wire by electrophoresis, the control of the cracking on the YBCO, BSCCO superconductor deposited on Ag wire in acetone and buthanol solution with PEG(poly-ethylenglycol) was investigated with XRD and SEM analysis. After deposition, drying and heat treatment process, the cracks on the deposited surface of YBCO and BSCCO samples was clearly removed and decreased, which was perpared in suspension with addition of PEG from 1 to 3ml. However, in the case of the addition rate of PEG in acetone suspension was exceeded in 3ml, BSCCO superconductor deposited on Ag wire was slightly melted at 90$0^{\circ}C$ which was the same heat treatment condition of other samples with different additin rate of PEG. In the process of electrophoretic deposition, drying and heat treatment, PEG added into the suspension solution as a binder was very useful to prepare the crack-free thick film-wire of YBCO and BSCCO.

• Journal of the Korean Wood Science and Technology
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• v.47 no.6
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• pp.732-750
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• 2019

Air drying was carried out on 15 Korean red pine logs to provide a prediction model of the moisture content (MC) change in the wood during drying. The final MC was 17.4% after 880 days since the beginning of air drying in the summer for 6 Korean red pine logs with 68.7% initial MC. The final MC was 16.0% after 760 days since the beginning of air drying in the winter for 9 Korean red pine logs with 35.8% initial MC. A regression model with R-squared of 0.925 was obtained as a result of multiple regression analyses with initial MC, top diameter, temperature, relative humidity, and wind speed as independent variable and and MC change during air drying as dependent variable. The initial MC and top diameter, which is the characteristic of Korean red pine, have greater effect on the MC decrease during air drying compared to meteorological factors such as the temperature, relative humidity, and wind speed. Two-dimensional mass transfer analysis was performed to predict the MC distribution of Korean red pine logs during air drying. Two prediction models with different air drying days and different meteorological factors for the determination of the diffusion coefficient and surface emission coefficient were presented. The error between the different two methods ranged from 0.1 to 0.8% and the difference from the measured value ranged from 2.2 to 3.6%. By measuring the internal MC during air drying of Korean pine logs with various initial MC and diameter, and calculating the moisture transfer coefficient in wood for each meteorological condition, the error of the prediction model can be reduced.

• Journal of the Korean Wood Science and Technology
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• v.40 no.2
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• pp.61-70
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• 2012

In this study the effect of heartwood-coating (HCO), vapor-dam (VD), bark-remaing (BR) and bark-remaining- coating (BRC) treatments were evaluated during air circulating oven-drying of hollowed round-post of Korean red pine. Hollowed round-post could be dried from the green condition to approximately 6% MC within 84 to 156 hours for the UC, HCO and VD specimens and it took 72 to 240 hours to about 8% MC, which is recommended as the indoor in-use MC. The temperatures in the hole of the Control (UC) and HCO specimens constantly showed a higher-leveled distribution pattern than those inside wood. The vapor pressure in the hole of the UC, HCO and BR specimens was higher than that inside wood and showed difference as highest value of about 20 mbar. The surface checks of all specimens were mild and were observed in increasing order of BRC, BR, UC, VD and HCO specimens.