• Journal of the Korean Ceramic Society
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• v.30 no.7
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• pp.535-542
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• 1993

It was investigated in this study that a preparation method, activation energy, surface area, pore volume, pore size distribution and DTA analysis of the dry gel in process of producing monolithic porous gel in Li2O-Al2O3-TiO2-SiO2 system by the sol-gel technique using metal alkoxides. Activation energy for gellation according to the variation of water concentration and the kind of catalysts ranged from 10 to 20kcal/mole. Monolithic dry gels were prepared after drying at 9$0^{\circ}C$ when the amount of water for gellation was 4~8 times more than the stoichiometric amount, that was necessary for the full hydrolysis of the mixed metal alkoxide. The specific surface area, the pore volume, the average pore radius of the dried gel at 18$0^{\circ}C$ according to the various kinds of catalyst were about 348~734$m^2$/g, 0.35~0.70ml/g and 10~35$\AA$, respectively. It showed that the dry gels were porous body. As a result ofthe analysis of DTA, it was confirmed that the exothermaic peaks at 715$^{\circ}C$ and 77$0^{\circ}C$ was clue to the crystallization of dried gel.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.421-421
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• 2008

Generally, the polymer thick-film resistors for embedded organic or hybrid substrate are patterned by screen printing so that the accuracy of resistor pattern is not good and the tolerance of resistance is too high(${\pm}$20~30%). To reform these demerits, a method using Fodel$^{(R)}$ technology, which is the patterning method using a photosensitive resin to be developable by aqueous alkali-solution as a base polymer for thick-film pastes, was recently incorporated for the patterning of thermosetting thick-film resistor paste. Alkali-solution developable photosensitive resin system has a merit that the precise patterns can be obtained by UV exposure and aqueous development, so the essential point is to get the composition similar to PSR(photo solder resist) used for PCB process. In present research, we made the photopatternable resistor pastes using 8 kinds of epoxy acrylates and a conductive carbonblack (CDX-7055 Ultra), evaluated their developing performance, and then measured the resistance after final curing. To become developable by alkali-solution, epoxy acrylate oligomers with carboxyl group were prepared. Test coupons were fabricated by patterning copper foil on FR-4 CCL board, plating Ni/Au on the patterned copper electrode, applying the resistor paste on the board, exposing the applied paste to UV through Cr mask with resistor patterns, developing the exposed paste with aqueous alkali-solution (1wt% $Na_2CO_3$), drying the patterned paste at $80^{\circ}C$ oven, and then curing it at $200^{\circ}C$ during 1 hour. As a result, some test compositions couldn't be developed according to the kind of oligomer and, in the developed compositions, the measured resistance showed different results depending on the paste compositions though they had the same amount of carbonblack.

• Korean journal of food and cookery science
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• v.32 no.1
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• pp.1-8
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• 2016

This study aimed to enhance the applications of dates as a food material that can be utilized and stored easily by improving the inefficient process of the traditional cooking procedure. To this end, this study investigated the physico-chemical and nutritional properties of jujube pulp powder, and compared the traditional and newly developed methods of making yakbap, yakpyon, and jujube porridge. According to the analysis of physical and chemical properties, the jujube pulp powder contained 5.4% moisture, 2.6% crude ash, 6.6% crude protein, 0.35% crude fat, and 4.7% crude fiber. The water activity was 0.95% in jujube pulp while it was 0.24% in jujube pulp powder. In addition, the jujube pulp powder had a total sugar content of 70.4% and reducing sugar content of 6.3%. The vitamin C was content was estimated to be 68.5 mg/100 g in the jujube pulp powder and the jujube pulp contained 6.2 g/100 g of dietary fiber. Major minerals were K, Mg, and Ca. After appointing jujube pulp powder (new method) to a test group and jujube pulp (traditional method) to a control group, the sensory evaluation and acceptance testing were conducted for yakbap, yakpyon, and jujube porridge. As a result, there was no significant difference in any sensory factors tested (p<0.05). It was found that making and storing jujube pulp powder by drying jujube pulp is a useful way of utilizing jujube because Yakbab, Yakpyun and jujube porridge were found to have a relatively good appearance, color, flavor, taste, texture and overall acceptance.

• Journal of the Korean Ceramic Society
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• v.34 no.1
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• pp.70-78
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• 1997

3Y-TZP/SUS316 Functionally Graded Material (FGM) was fabricated by slip casting method. Alumina mold was used to overcome problems of gypsum mold in slip casting process, and the optimal dispersion con-ditions of 3Y-TZP/SUS316 binary slurries was determined using electrokinetic sonic amplitude and a viscometer, and observing sedimentation behavior. The properties of the specimens casted by gypsum mold and alumina mold were compared in terms of changes in shrinkage rate, drying and sintering conditions, and microstructure. It was found that the specimens obtaine from the alumina mold showed a clean surface, easier thickness control of each layer, and higher productivity. Especially, no degradation was observed in the SUS316 prepared using alumina mold. Thus it is desirable to use porous alumina mold rather than gyp-sum mold for the slip casting of 3Y-TZP/SUS316-FGM.

• Fashion & Textile Research Journal
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• v.16 no.2
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• pp.326-332
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• 2014

To develop cool touch feeling fabrics for summer clothing material, it was manufactured several compositions of woven fabrics, having rayon multi-filament yarn (non-twisted) as warp and various kinds of yarn, such as viscose rayon multi-filament yarn (twisted), tencel$^{(R)}$ spun yarn, PET high absorbance quick dry filament yarn, and PET based rayon-like yarn, as weft. After preparing the fabrics, basic properties of the fabrics were investigated, such as air-permeability, tensile strength, absorption rate, drying rate, etc. Also, surface warm / cool sensations of the woven fabrics were assessed by Qmax Warm / Cool Touch Tester. It was observed that the fabrics composed of viscose rayon multi-filament yarn (warp) and PET high absorbance quick dry filament yarn (weft) showed excellent surface cool touch sensation-the highest Qmax value. This is because the fabric having flat shaped PET high absorbance quick dry filament shows the largest contact area with Qmax measuring plate. And, the fabric also showed superior high absorbance and quick dry property as expected. In addition, we treated phase change material (PCM) on the surface of the fabric composed of viscose rayon multi-filament yarn (warp) and PET high absorbance quick dry filament yarn(weft) to improve the cool touch feeling. However, the surface cool touch feeling was impaired by resin treated with PCM during the finishing process.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.5
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• pp.565-569
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• 1993

Antioxidative activity of browning product(BP) fractionated from fermented soybean sauce(SS) was studied during the oxidation process of linoleic acid mixture system. SSBP was a powder type product prepared from fermented soybean sauce by the fractionation through the Sephadex G-10 column and freeze drying of collected fraction. The aqueous model systems were used for the evaluation of antioxidative activity of SSBP during the oxidative reaction at $50^{\circ}C$ by the determination of peroxider and conjugated dienoic acid compounds. The linoleic acid mixture for the aqueous model systems was consisted of linoleic acid(64.6%), oleic acid(27.4%), and other acids in ethanolic phosphate buffer solution(pH 7.0). SSBP had a considerable antioxidative activity with the inhibition of formation of peroxides and conjugated dienoic acids during the autoxidation of linoleic acid mixtures in aqueous model systems. Antioxidative activity of SSBP was relatively higher than SS, however, lower than ${\alpha}-tocopherol$ and butylated hydroxyanisol. The antioxidative effect of SSBP was increased by the its concentrations from 0.05% to 0.5% in the oxidation reactions of aqueous model systems. Therefore, SSBP was considered as one of the potential natural antioxidants for the use of food products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.5
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• pp.570-575
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• 1993

Antioxidative characteristics of melanoidin related products(MRPs) fractionated from fermented soybean sauce were studied during the oxidation process of model systems. MRPs were prepared from soybean sauce fermented for 6 months after inoculation Aspergillus oryzae by the fractionation through the Sephadex G-10 column and the freeze drying of collected fractions. MRPs inhibited the formation of peroxides during the oxidation of linoleic acids mixture in ethanolic phosphate buffer solution at $50^{\circ}C$ with the increasing tendency by their concentration in reaction systems. MRPs had hydrogen doner properties during the reaction with ${\alpha},\;{\alpha}'-diphenyl-{\beta}-picrylhydrazyl$ and also MRPs inhibited the iron and lipoxygenase catalytic oxidation. MRPs were found to be fairly stable with no loss of antioxidative effect after storage at $50^{\circ}C$ for 15days.

• The Korean Journal of Mycology
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• v.23 no.2 s.73
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• pp.161-175
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• 1995

Meju is a raw material used to make Korean soy sauce (Kanjang) and soybean paste (Doenjang), both of them rich in plant protein. The twenty-nine fungal and a bacterial species were identified from twenty-three traditionally homemade meju cakes. Out of them, only a few species were found to be involved in the actual fermentation process of meju; The other species were contaminants during the improper subprocesses of meju fermentation. The fungal floral successions were observed to be related to two physical and biochemical changes of meju cakes during meju fermentation: drying and heat releasing processes. The zygomycetous fungi were first observed to exist mainly during the first stage. Scopulariopsis brevicaulis was observed to grow on the surface of meju cakes and then to coexist with Bacillus megatrium in the inner part of meju cakes during the second stage. Based on the biochemical tests, the proteases secreted by the different microorganisms were involved in the degradation of soybean proteins with a mutual relationship. Also, zygomycetous fungi were speculated to be important microorganisms for inducing the second stage in the traditional Korean homemade meju.

• Korean Journal of Materials Research
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• v.11 no.10
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• pp.869-878
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• 2001

Alumina $(Al_2O_3)$ green bodies were fabricated by gel-casting using three kinds of alumina with different particle size (mean particle size: 4.6 $\mu\textrm{m}$, 0.32 $\mu\textrm{m}$, 10nm). The effects of particle size on gel-casting process and green microstructure were investigated. The optimum dispersion conditions using ammonium salt (D-3019) as dispersant were 0.2 wt% (4.63 $\mu\textrm{m}$), 0.5 wt% (0.32 $\mu\textrm{m}$), and 5.0 wt% (10 nm), in high solid loading. The optimum solid loading of each starting material for gel-casting was obtained as 59 vol% (4.63 $\mu\textrm{m}$), 57 vol% (0.32 $\mu\textrm{m}$), 15 vol% (10 nm), depending on particle size, indicating that nano-size particle (10 nm) represent lower solid loading as high specific surface area than those of other two starting materials. The drying at ambient conditions (humidity; $\thickapprox$90%) was performed more than 48hrs to enable ejection of the part from the mold and then at $120^{\circ}C$ for 2hrs in an air oven, showing no crack and flaw in the dried green bodies. The pore size and distribution of the gelcast green bodies showed the significant decrease with decreasing particle size. Green microstructure was dependent on the pore size and distribution due to the particle size, and on the deairing step. The green density maximum obtained was 58.9% (4.63 $\mu\textrm{m}$), 60% (0.32 $\mu\textrm{m}$), 47% (10 nm) theoretical density (TD), and the deairing step applied before gel-casting did not affect green density.

• KSBB Journal
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• v.27 no.6
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• pp.347-351
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• 2012

This study was conducted to optim ize the composition of CEM (cabbage extract medium) and cryoprotectants on the growth of Lactobacillus plantarum, a probiotics growing in plant and milk. For this, we analyzed the growth characteristics of Lb. plantarum in CEM and subsequently optimized the medium composition by addition of carbon, nitrogen sources and buffering agents. Among carbon sources, glucose showed the best result to increase the cell density after dilution of CEM. When 0.5% yeast extract and 1% soy peptone were supplemented in the diluted CEM, Lb. plantarum grew up to the maximum cell density. Addition of buffering agents in CEM was not significantly effective to increase the cell density. Meanwhile, addition of 12% skim milk, 5% sucrose and 0.5% glycerol showed a cryoprotective effect against cell damage of Lb. plantarum during freeze drying process showing high survival rate after 150 days. This optimized CEM can be used for economical production of bacterial cells particularly originated from a plant-related ecosystem.