• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.761-762
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• 1988

This paper is to investigate dielectric properties, dielectric breakdown strength, varing of interior organization and gelling point temperature as parameter of post-cure conditions of thermo-setting epoxy resin.

• Journal of the Korean Ceramic Society
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• v.31 no.4
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• pp.367-374
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• 1994

Inorganic-organic composite was made through sol-gel process. Possible range for hosting organic dye was investigated with various composition. The transmittance of the composite was the most important condition for a host was increased to 90% with decreasing HCl as a catalyst. Clear absorbance peak was obtained by decreasing concentration of organic dye, fluorescent intensity was increased and transmittance was decreased with rising gelling temperature.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.483-486
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• 1995

With a view to increase utility of ethanol fractionated fish skin gelatin as a food source, the effect of gelation condition on physical properties of the gelatin was investigated. The physical properties of gelatins treated with or without ethanol were improved with a concentration of gelatin increased. The properties such as gel strength, melting point and gelling point of 10% gelatin sol or gel were reached to maximum at pH 6.0 in ethanol treated gelatin and pH 5.0 in non treated one, respectively. Gel strength and melting point of both gelatin gels chilled for long time at low temperature were superior to those of both gelatin gels chilled for short time at high temperature. Gel strength, melting point and gelling point of ethanol treated gelatin gel or sol prepared under optimized gelation conditioning were superior to those of non treated one.

• Korean journal of food and cookery science
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• v.19 no.4
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• pp.511-520
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• 2003

This study was carried out to determine the effects of various contents of kiwifruit contents on the quality characteristics of mixed polysaccharide gels made from $\kappa$-carrageenan and locust bean gum. The color value, gelling temperature, melting temperature, break down rate, syneresis, rupture properties, TPA properties and sensory properties of mixed polysaccharide gels with various contents of kiwifruit contents were measured. As the kiwifruit contents was increased, the lightness (L), yellowness (b) and greenness (-a) of the mixed polysaccharide gels increased. There were no differences in the color values of gels during storage. As the kiwifruit content was increased, the gelling and melting temperatures of the mixed polysaccharide gels also increased. The mixed polysaccharide gels with high kiwifruit contents were difficult to melt, and it seemed that the addition of kiwifruit to the mixed polysaccharide gels could improve the thennal stability of the gels. The syneresis of the gel increased with increasing storage time, whereas the addition of kiwifruit to the gel resulted in suppression of syneresis. With regard to the rupture properties, stress, energy and strain, they were all decreased with increasing kiwifruit contents. The TPA properties, adhesiveness, hardness and chewiness increased and cohesiveness decreased with increasing kiwifruit contents. The results showed that the gel became tough and adhesive, and could be easily broken under small deformation, with increasing kiwifruit contents. The sensory evaluation showed that the green color, aroma, sweetness and sourness increased with increasing kiwifruit contents. The texture, adhesiveness, springiness and cohesiveness decreased, and brittleness and hardness increased, with increasing kiwifruit contents. The overall acceptability of the gel with 30% kiwifruit content was the highest. Thus, mixed polysaccharide gels made from kiwifruits could be useful, as the addition of kiwifruit to a mixed polysaccharide gel results in a good aroma, taste and stability, despite a lowering of the textural properties.

• The Korean Journal of Food And Nutrition
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• v.10 no.2
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• pp.234-240
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• 1997

Agar has widely been used as medical aids and food ingredients due to its pecular physicochemical and rheological properties. In this paper, the effects of spray drying and extrusion drying on functional properties of agar were investigated to clarify the sol-gel transition mechanism at low temperature and microstructure of agar gel by measuring phase transition by differential scanning calorimetery, structural differences by light microscope and scanning electron microscope observation. The lowest endothermic onset(To), peak(Tp), conclusion(Tc) temperature and enthalpy($\Delta$H) using differential scanning calorimetery were showed in extrusion-dried agar wic were checked in 41.30, 61.72, 80.50 and 0.73cal/g. In cases of unmodified and spray-dried, the values were 81.20, 95.51, 112.14 and 3.22cal/g, and 60.11, 76.45, 89.54 and 1.53cal/g, respectively. When all samples were reheated using differential scanning calorimetery after gelling fully, no significant differences of endothermic To, Tp, Tc and $\Delta$H appeared. The surface structure of unmodified agar powder observed by light microscope and scanning electron microscope appeared a continuous surface without any indication of small pores, gaps or point of discontinuity. In cases of spray-dried agar, the unstable structures with pores was resulted. The microstructures of extrusion-dried agar, however, was solid with large gaps and areas of discontinuity in the surface. From the results above, it was suggested that significant differences in phase transition and surface microstructures were clearly related to the physicochemical changes and rheological properties, solubility and gelling ability of the types of agar gel.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.810-812
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• 1988

This paper is to investigate dielectric properties and new fabrication method of Glass-Cloth/Epoxy composite materials. According to the results of this paper, gelling point temperature is affected significantly on the ambient temperature. And Tan${\delta}$ characteristics of Glass-Colth/Epoxy composite materials is also affected significantly on the state of interior void of glass cloth and interface coupling between epoxy resin and glass cloth.

• Korean Journal of Microbiology
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• v.28 no.3
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• pp.274-277
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• 1990

The hyphal tip phenoloxidases of Coprinus congregatus were localized by the protoplast-concanavalin A method. Protoplast were generated from cultures grown on a solid medium which was solidified with a new gelling agent, Pluronid Polyol F127, instead of agar. the enzymes were associated with the cell membrane which might work as a transducer in the light recepter complex.

• Journal of Microbiology
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• v.34 no.4
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• pp.384-386
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• 1996

Application of polyacrylamide gel (PAG) instead of agar to solid cultures of Streptomyces spp. was studied. The improved media were prepared by 1) gelling 20 ml of 5% acrylamide in a glass petri dish at room temperature, 2) washing by running water for more than 8 hr to remove residual reaction reagents, 3) drying at 5$0^{\circ}C$ for 12 hr to make a gel film, 4) autoclaving at 121$^{\circ}C$ for 15 min, and 5) swelling gel for about 4 hr by adding sterile liquid medium. In PAG media there were no differences from the observation of morphological characteristics showing during the cellular differentiation on agar media, whereas the ability to utilize carbohydrates differed somewhat from agar media. Agar media thus were little favorable for biochemical tests which the growth was determined depending on the formation of colony, but washed PAG was superior to serve as a solidifying agent.

• Journal of the Korean Ceramic Society
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• v.25 no.2
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• pp.136-142
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• 1988

β-Al2O3, which is used for solid electrolyte membrances in sodium-sulfur batteries, was prepared by sol-gel process. Sodium-n-propoxide NaOC3H7 and aluminum-isopropoxide Al(OC3H7)3 were hydrolyzated in the solution at pH 3, pH 7, pH 9 and pH 11, respectively. The sol-gel processed samples were calcined at several temperature steps, respectively and analysed by thermal analyser(DT-TGA), infrared spectrum analyser and X-ray diffraction analyser. The gelling rate of solution at pH 7 was much higher than that of the solution at pH 3. Thermal exchanging behavior of the gels at pH 3 were similar to Na2O·Al2O3·6H2O and, above pH 7, were similar to Na2O·Al2O3·3H2O. When samples' composition ratio was 9.13 : 90.87 [NaOC3H7:Al(OC3H7)3] at pH 7, β-Al2O3 was formed at 1100℃.

• Journal of the Korean Ceramic Society
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• v.34 no.11
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• pp.1187-1197
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• 1997

Dry gel composed of primary particles more homogeneous than starting boehmite powder was prepared by dispersing and gelling the boehmite powder. The transformation temperatures of boehmite powder, dry gel seeded with 0, 1, 3, 5 wt% $\alpha$-Al2O3, and ball milled gel were 1192$^{\circ}C$, 1184$^{\circ}C$, 1141$^{\circ}C$, 1119$^{\circ}C$, 1117$^{\circ}C$, and 1106$^{\circ}C$, respectively. Sintering behavior of dry gel without seed was similar to that of boehmite powder, but the sintered density of dry gel was improved as much as 10%~15% than boehmite powder. In the case of dry gel seeded with 5 wt% $\alpha$-Al2O3, sintering behavior was much improved. The relative density of the gel seeded with 5 wt% $\alpha$-Al2O3 was 96% when sintered at 140$0^{\circ}C$ for 1h. On the other hand, ball milling of the non-seeded sol for 48h resulted in the relative density of 97% when sintered at 130$0^{\circ}C$ for 1h. The size and amount of $\alpha$-Al2O3 particles added by ball milling were 0.107 ${\mu}{\textrm}{m}$ and 0.5 wt%.