• Journal of Conservation Science
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• v.9 no.1
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• pp.1-10
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• 2000

In 1993, many bronze artifacts were excavated from the Sanoesa Temple(思惱寺), Chongju, Chungbuk. Twelve items were selected and chemically analyzed with AA Spectrometry and ICP-Atomic Emission Spectrometry. They were also observed under the optical microscopy and SEM. According to the results from chemical analysis, production method and use, these artifacts were classified into four groups: casting, wrought and welding products, and bells. Cast products, probably used for ritual, were alloy of 70% Cu, 10% Sn and 20% Pb. They showed ${\alpha}+{\beta}$ phase as a typical microstructure of casting. The ${\delta}$ phase was rarely observed due to the small amount of Sn. These artifacts included more lead than other alloys. They showed segregation like island-shape on the lead part. Wrought products used for daily too1s. were alloy of 80% Cu and 20% Sn. Since they were consist of ${\alpha}$ phase and martensite ${\beta}$ phase, it could be presumed that they were heat-treated. The production method could be identified from twinned grains in ${\alpha}$ phase. Lead was not included in because it had a bad effect to alloy. The bells were alloyed with 85% Cu, 10% Sn, 5% Pb or 90% Cu and 10% Sn. They show the dendrite structure because they were cast and alloyed with many tin. Weldinged were alloyed with 83% Cu, 12% Sn and 5% Pb. lt showed the fine dendrite structure because of fast cooling in air.

• Clinical and Experimental Reproductive Medicine
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• v.19 no.2
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• pp.143-152
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• 1992

The present experiments were focussed to modify a short slow-cooling protocol used for freezing of early stage embryo(Testart et al., 1986) and also to apply the modified method for the cryopreservation of hamster oocytes with Zona or without. The protocol was modified by changing the 4-step equilibration into 1-step and the 1-step thawing into 2-step. The oocytes were added in 1.5M PROH and 0.1M Sucrose, seeded at $-7^{\circ}C$, slow cooled($0.3^{\circ}C$/min) to $-30^{\circ}C$ before plunging to $-196^{\circ}C$. The oocytes were thawed at $23-25^{\circ}C$ air(20sec/150sec) and/or 33-35 water(10sec). The survival of the frozen-thawed oocytes was determined by morphologic criteria and their fertilizing ability was also estimated by Sperm Penetration Assay(SPA) system(Chang et al, 1990) using fertile men semen sample. One-step equilibration showed slightly higher survival rate(83.9% vs. 71.0%) and fertilization rate(83.9% vs. 71.0%) compared with four-step(p>0.05). And two-step thawing(air & water exposing) of oocytes frozen after 1-step equilibration showed significantly higher survival rate(96.3%) than one-step thawing at air(85.2%) or water(65.0%) only(p<0.05). Therefore, by the modified method(l-step equilibration & 2-step thawing), Zona-intact(ZI) and Zona-free(ZF) oocytes were frozen and thawed. ZI-oocytes showed significantly higher survival rate(95.4%, 308/323 vs. 67.6%, 240/355) than ZF-oocytes(P<0.01). But the survival of ZF-oocytes was as high as ZI-oocytes in fourteen of twenty-four replicates. ZI-oocytes was also significantly higher fertilization rate($92.4{\pm}8.9%$ vs. $63.7{\pm}18.5%$) and higher mean number of penetrated sperm($6.2{\pm}4.2$ vs. $3.9{\\pm}3.3$) than ZF-oocytes, but not higher than control(fresh oocytes;$99.3{\pm}2.4%$, $8.4{\pm}4.2$)(P<0.001). Conclusively, this modified method will contribute to freeze effectively the hamster oocytes for simplifing of the logical consideration of performing SPA and also to freeze the human and other animal oocytes.

• Applied Biological Chemistry
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• v.27 no.2
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• pp.55-63
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• 1984

Lethal effect on Chinese radish Kimchi was investigated by using a pilot scale Kimchi pasteurizer. A simulation model was presented so as to predict the change in viable cell concentration of the Kimchi during pasteurization. D values of microorganisms in the Kimchi were found to be 2.21, 1.62, 0.73, 0.39 and 0.21min at 60, 64, 70, 75 and $80^{\circ}C$, correspondingly, and thereby z value was $19^{\circ}C$. One cycle time required was 0.99min at flow rate of 4 l/min. The ratio of lethality in preheating section to total lethality was 0.3 and the ratio of lethality in holding, precooling and cooling sections to total lethality was 0.7. The experimental data were in good agreement with the values simulated by two model equations to which linear and exponential temperature profiles were applied at $65^{\circ}C\;and\;70^{\circ}C$ in holding section.

• KSBB Journal
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• v.10 no.1
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• pp.63-70
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• 1995

The effect of operating conditions on separation of soybean proteins in a home-made free-flow electrophoresis apparatus was investigated. Measurement of the pH, conductivity, and UV-absorbance(280 nm) were carried out at each run and the purity of the sample was tested with SDS-PAGE analysis. The soybean extract pretreated with Tris and boric acid was mixed with the amino acids composed of glutamic acid, histidine, arginine, glycine(1 mM each) with glycyl-glycine(2mM) and KCl(1mM). When the cellulose acetate was used as a compartment between the electrode and the buffer solution in the cell, pH distribution in the separation cell varied from 3.0 at the anodic side to 8.0 at the cathodic side and had two inflection point. The applied voltage was from 300V to 1000V and the separation was better at a higher voltage but the voltage was limited by the capability of the cooling system due to Joule heat. The proteins focused near the middle of the channel. From the change of pH and conductivity it was found that the ions in the channel moved out to the electrodes through the membrane. In the case when the concentration of the buffer solution was increased 5 times, proteins were focused at 300V. We could not increase up to the ten times of the concentration since the temperature difference between inlet and outlet was more than $25^{\circ}C$ and denaturation of proteins was expected. When ion-exchange membranes were used U-type pH distribution was set up due to the ionic polarization near the membrane. The commercial ampholytes, instead of the mixed amino acids showed not much improvements in purity of the separated sample.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.6
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• pp.453-458
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• 2002

High temperature sterilization method (30min. at $40^{\circ}C$longrightarrow30 min. at $70^{\circ}C$longrightarrow30 min. cooling at $20^{\circ}C$) was evaluated better than that of chloride, ion water, $O_3$ water, and salt water for the controling of micro-organisms at the early stage of sprout culture. Due to the improved germination rate and effective control of micro-organisms at early stage, the method resulted in much lower in the number of micro-organisms, higher in sprout yield, and 2 days longer in quality keeping at market than sprouts prepared by conventional method. There are two methods related with water temperature; constant temperature method (18.5$\pm$ $0.5^{\circ}C$) which keeps the same water temperature during the culture and 3-stage temperature method which changes the water temperature depending on the days after culture. Three-stage temperature method set the temperature at 21$\pm$ $1^{\circ}C$) in the second and third days after the initial acceleration of germination (about 4 hours), at 18.5$\pm$0.5$^{\circ}C$ in the fourth and fifth days, and at 17.0$\pm$ $0.5^{\circ}C$) in the sixth and seventh days. Three-stage temperature method could enhance the resistance power to diseases at the early growth stage, control the growth to standard goods (8-9cm in length and 2.15-2.30mm in width), and keep good body color at the middle or final stage. This method also increased the sprout yield by 6% compared with the conventional method, constant temperature method.

• The Korean Journal of Food And Nutrition
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• v.17 no.2
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• pp.163-170
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• 2004

Effect of several factors for Preparation of whole egg gel (WEG) on texture and color of WEG were investigated in this study. The factors studied were amount of water addition, heating temperature and time, pH and NaCl. The whole egg gel was prepared by mixing of whole egg and steaming at 100$^{\circ}C$ for 7 min followed by cooling at 22$^{\circ}C$ for 90 min. The results showed that the increase in water addition decreased significantly with viscosity values of whole egg solution (WES) and the addition of more than 50％ water resulted in a significant decrease in the stress at failure (SF) and the hardness of WEG. The color a and b values of WES decreased and the value of WEG also decreased significantly in negative range. The increase in heating temperature decreased the coagulation time and increased in SF while SF decreased. Addition of NaCl up to 1.3％ resulted a significant increase in SF and hardness and a little changes in color of WEG. As the pH of WES changed from 4.0 to 10.0, the viscosity of WES was minimal and SF and hardness were maximal at pH 6.0. The L and b values of WEG were significantly reduced at higher pH values of 8.0.

• Korean Journal of Materials Research
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• v.2 no.1
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• pp.65-75
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• 1992

0.4wt%C steel added with V and/or Nb were forged and followed by air cooling. The structure-property relationships were examined and multiple regression analysis was conducted to quantify the magnitudes of effects of microalloying elements on the properties of the steels. All material's tensile strength are greater than $70kg/\textrm{mm}^2$, so they are equal to or superior to Q/T material's(S45C). Their impact energies are less than 40J, so they are 50% of Q/T material's. Increasing the content of V from 0.10 to 0.15 wt% had brought improvement in UTS about 20% but with some sacrifice of impact energy. These were the results from the precipitation strengthening by fine dispersion of VC in ferrite, increment of pearlite volume fraction and decrement of pearlite interlamellar spacings. However, increasing the content of Nb from 0.05 to 0.l0wt % slightly improved UTS and impact energy. NbC precipitates were more effective in suppression of austenite grain coarsening than VC precipitates. Combined additions of V+Nb were more effective to bring impact toughness than sole addition. Optimum combination of strength and toughness was accomplished wish 0.4C-1. 19Mn-0.05S-0.12V-0.07Nb steel.

• Reproductive and Developmental Biology
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• v.35 no.1
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• pp.55-60
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• 2011

The objective of this study was carried out to evaluate the efficiency of sperm collection methods on the post-thaw viability of cat semen. The cat semen was collected by artificial virginal (AV) and electronic ejaculate (EE) methods. The composition of semen extender was consisted of Tris-buffer supplemented with 20% egg yolk and 1% P/S antibiotics in Ext I, and more added 8% glycerol, 1.0% Equex STM paste of total volume in Ext II. The collected semen was adjusted the concentration and then diluted in Ext I for optimal concentration. The diluted semen was cooling to $5^{\circ}C$ temperature in refrigerator for at least 2 hrs and then diluted stepwise with Ext II for at least 1 hrs. After an equilibration for 1 hrs, the cooled semen was packaged in 0.5 ml straw and then freezing on the $LN_2$ vapor over 5 cm above from $LN_2$ and then immersed directly in $LN_2$ for cryopreservation. The frozen semen was thawed in $38^{\circ}C$ water for 15 sec and then evaluated the motility, viability, and morphology. Post-thaw semen were calculated the motility by SMI (sperm motility index). The live-dead sperm was evaluated by Eosin-B and morphological evaluation was by Diff-quik kit staining. The post-thaw concentration ($89{\times}10^6$ /ml vs. $128{\times}10^6$ /ml), viability ($22.6{\pm}10.6%$ vs. $37.1{\pm}26.1%$), morphological normality ($27.0{\pm}50.2%$ vs. $45.6{\pm}123.0%$) of EE and AV groups were not significant different, but the post-thaw motility was significant lower in EE than that in AV group ($53.1{\pm}3.6$ vs. $73.6{\pm}5.7$) (p<0.05). In conclusion, semen collection methods did not significant different between EE and AV groups except of post-thaw motility and so both semen collection methods could be applied in feline semen collection methods.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.1
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• pp.221-243
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• 1997

The objective of this study was to characterize the mechanical properties of $Y_{2}O_{3}$-containing glass infiltrated ceramic core material, which was made by pressureless powder packing method. A pure alumina powder with a grain size of about $4{\mu}m$ was packed without pressure is silicon mold to form a bar shaped sample, and applied PVA solution as a binder. Samples were sinterd at $1350^{\circ}C$ for 1 hour. After cooling, $Y_{2}O_{3}$-containing glass($SiO_{2},\;Y_{2}O_{3},\;B_{2}O_{3},\;Al_{2}O_{3}$, ect) was infiltrated to the sinterd samples at $1300^{\circ}C$ for 2 hours and cooled. Six different proportions $Y_{2}O_{3}$ of were used to know the effect of the mismatch of the thermal expansion coefficient between alumina powder and glass. The samples were ground to $3{\times}3{\times}30$ mm size and polished with $1{\mu}m$ diamond paste. Flexural strength, fracture toughness, hardness and other physical properties were obtained, and the fractured surface was examined with SEM and EPMA. Ten samples of each group were tested and compared with In-Ceram(tm) core materials of same size made in dental laboratory. The results were as follows : 1. The flexural strengths of group 1 and 3 were significantly not different with that of In-Ceram, but other experimental groups were lower than In-Ceram. 2. The shrinkage rate of samples was 0.42% after first firing, and 0.45% after glass infiltration. Total shrinkage rate was 0.87%. 3. After first firing, porosity rate of experimental groups was 50%, compared with 22.25% of In-Ceram. After glass infiltration, porosity rate of experimental groups was 2%, and 1% in In-Ceram. 4. There was no statistical difference in hardness between two materials tested, but in fracture toughness, group 2 and 3 were higher than In-Ceram. 5. The thermal expansion coefficients of experimental groups were varied to $4.51-5.35{\times}10^{-6}/^{\circ}C$ according to glass composition, also the flexural strengths of samples were varied. 6. In a view of SEM, many microparticles about $0.5{\mu}m$ diameter and $4{\mu}m$ diameter were observed in In-Ceram. But in experimental group, the size of most particles was about $4{\mu}m$, and a little microparticles was observed. The results obtained in this study showed that the mismatch of the thermal expansion coefficients between alumina powder and infiltrated glass affect the flexural strength of alumin/glass composite. The $Y_{2}O_{3}$-containing glass infiltrated ceramic core made by powder packing method will takes less time and cost with sufficient flexural strength similar to all ceramic crown made with slip casting technique.

• The Journal of the Petrological Society of Korea
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• v.8 no.2
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• pp.92-105
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• 1999

The Cretaceous Chaeyaksan basaltic rocks consist mainly of basaltic tuffs intercalating three layers of basalt. Stratigraphically, the rocks are located between the upper Songnaedong Formation and the lower Geoncheonri Formation and contain plagioclase, augite, hornblende, and a few olivine phenocrysts. Geochemically, they show calc-alkaline characteristics in some immobile element content, but show the alkaline suite feature in the mobile major element composition. The basalts are widely spilitized but some of them is altered to shoshonitic rocks with more calcic plagioclase, calcite, and chlorite, and adularia veinlets are common in the rocks. It is supposed that the post-eruption alteration of the rocks is done through alkali-replacement by hydrothermal solution or vapor rather than by low grade regional metamorphism. It is considered that A1 in hornblende will be available for estimating the pressure of the pre-eruption magma in the reservoir although the plagioclase of the rocks are highly albitized. The crystallization pressure was calculated as 5.7Kb by the equation of Johnson and Rutherford(l989) incorporating of the effect of overestimate of .41T in hornblende in the case of quartz-free rocks. Application of the estimated temperature, pressure and the constituent of phenocrysts of the rocks to the experimental P-T phase diagram for basalts established by Green(1982) indicates the crystallization course and succession of growth of the phenocrysts during of rising and cooling of the magma reservoir; augite + augite and olivine + augite, olivine, and hornblende -+ augite and hornblende+ augite, hornblende, and plagioclase. Such evolution course of the magma may include crystal fractionation by the phenocrysts crystallization and contamination by country rock in lower crust.