• Journal of the Korean Ceramic Society
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• v.35 no.5
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• pp.479-485
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• 1998

Raw mateials such as limestone quartzite bauxite and anhydrite were used in the production of mod-ified beloite cement. Two kinds of clinker were synthesized with relatively higher content of $C_2S$ than that of $C_4A_3{\={S}}$ Concerning $C_2S$ the main mineral component borax ($Na_2O\;2B_2O_3\;10H_2O$) was added to stimu-late hydraulic reactivity and this would be possible by stabilizing ${\alpha}'-C_2S$ at room temperature. We had in-tended to compare burning and hydraulic characteristics of clinkers with one another by varying the amount of borax addition and to study the appropriate amount of anhydrite addition needed in the strengthening of cement during hydration. It was concluded that the effective amount of borax addition ne-eded for stabilization of ${\alpha}'-C_2S$ was 5 wt% in 60wt% $C_2S$ inclusive clinker and adding anhydrite in the ra-tio of 1.3 of $SO_3/Al_3O_3$ was appropriate in the production of cement by this clinker. Only ettringite was seen to contribute to the strength without additives but C-S-H was found to form along with ettringite with the addition of borax in the initial stage of hydration.

• 연구논문집
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• s.26
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• pp.103-112
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• 1996

$Al_2O_3/SiC$ Hybrid-Composite has been fabricated by conventional powder process. The addition of $\alpha-Al_2O_3$ as seed particles in the transformation of $\gamma-Al_2O_3 to $\alpha-Al_2O_3$ provided a homogeneity of the microstructure, resulting in increase of mechanical properties. The grain growth of $Al_2O_3$ are significantly surpressed by the addition of nano-sized. SiC particles, increasing in fracture strength. The addition of SiC plates to $Al_2O_3$ nano-composite decreased the fracture strength, but increased the fracture toughness. Coated SiC plates with nitrides such as BN and /SiC$Si_3N_4$ enhanced fracture toughness much more than uncoated SiC plates by inducing crack deflection.

• The Korean Journal of Pharmacology
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• v.31 no.3
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• pp.365-375
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• 1995

The anemia-inducing strain of Friend virus (FVA) is a murine retrovirus which stimulates the proliferation of erythroid progenitor cells. The progenitor cells synthesized by FVA-stimulation are unable to proceed with differentiation and accumulate in the spleen resulting in splenomegaly in infected mice. Using FVA-inoculated mice as a model, we have investigated the antiretroviral effects of 2',3'-dideoxycytidine (ddC) and recombinant $interferon-{\alpha}-A\;(rIFN-{\alpha}-A)$ on FVA infection. The extent of the infection was determined by measuring the weights of the spleens. Daily intraperitoneal injection of ddC (100 mg/kg body weight), $rIFN-{\alpha}-A$ (10 KU/mose) and the combination of both drugs to FVA inoculated mice for 18 days resulted in suppression of the growth of spleens by 15.1%, 52.7% and 61.6%, respectively. When ddC was dissolved in drinking water (0.1 mg/ml) and administered to a group of FVA inoculated mice ad libitum, and $rIFN-{\alpha}-A$ (10 KU/mouse) was intraperitoneally injected daily to another group of ddC (0.1 mg/ml) drinking mice for 18days, the growth of spleens was suppressed by 38.4% and 83.2%, respectively. These results indicate that administration of ddC via drinking water is more effective in suppressing FVA infection than the daily injection of ddC, and that the combined effects ddC and $rIFN-{\alpha}-A$ are not synergistic but additive. In order to determine whether ddC treatment alters the characteristic of the progenitor cells with respect to $Ca^{++}$ uptake, $Ca^{++}$ uptake in erythroid cells and the effect of cyclohexyladenosine (CHA) on the $Ca^{++}$ uptake were studied. $Ca^{++}$ uptake in the erythroid progenitor cells was about 20-fold greater than in mouse erythrocytes and the inhibition of $Ca^{++}$ uptake by CHA was the greatest in the progenitor cells from FVA infected mice which were treated with ddC. The inhibition was obviated by theophylline. Results of CHA binding studies showed that the erythroid progenitor cells contain both high and low affinity CHA binding sites, whereas mose erythrocytes contain only the low affinity CHA binding sites.

• Journal of the Korean Ceramic Society
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• v.37 no.10
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• pp.949-954
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• 2000

천연원료를 사용하여 $\alpha$-C$_2$S-C$_4$A$_3$S계 시멘트를 제조하였다. 클링커의 특성분석은 XRDd, FT-IR, SEM으로 행하였고 플라이애쉬 첨가에 따른 강도변화와 유동성 및 수화발열속도를 검토하였다. 그 결과 플라이애쉬 첨가시 유동성 증가 및 ettringite와 stratling계 수화물의 생성으로 초기 압축강도가 증진되었다. 플라이애쉬 5wt% 혼합시 7일 모르타르 압축강도가 224kgf/$ extrm{cm}^2$, 90일 강도는 440kgf/$\textrm{cm}^2$ 이였다.

• Journal of Bio-Environment Control
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• v.9 no.2
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• pp.79-84
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• 2000

The growth and quality differences between common thyme(Thymus vulgaris L.) and lemon thym (Thymus$\times$citriodorus) were investigated. They were grown in a hydroponics culture system (DFT) with a nutrient solution developed by the European Vegetable R&D Center in Belgium. Nutrient solution ionic strength used were 1.2, 2.4, 4.8 and 7.2 mS.cm-1. The dry matter of two thymes were increased with increasing ionic strength, while shoot length, root length and fresh weight were decreased. Chlorophyll content was higher in lemon thyme, while vitamin C content and essential oil content were higher in common thyme. The essential oil content showed a similar trend as those of growth. The main compostion of essential oil were thymol and carvacrol in common thyme, and geraniol and $\alpha$-citral in lemon thyme. The highest content of these compounds was obtained in 1.2mS.cm-1 treatment. Consequently, the ionic strength of 1.2mS.cm-1 was suitable for the production of quality thymes.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.1
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• pp.36-42
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• 2007

To compare the survival rate of periodontal ligament cells preserved in storage media with good availability at the time of an avulsion injury, periodontal ligament cells were incubated in ${\alpha}-MEM$ culture medium containing 10% FBS in condition of $37^{\circ}C$, 5% $CO_2$. These cells were then cultured in HBSS, ${\alpha}-MEM$, milk(S co., P. co.) and tap water at the temperature of 4, 25, $37^{\circ}C$ each in 60 min. The groups were measured by MTT assay. The results were as follows : 1. Among the storage media at $4^{\circ}C$, ${\alpha}-MEM$ and P-milk had the highest preserving ability of periodontal ligament cells, while that of HBSS S-milk and tap was low in order. 2. Among the storage media at $25^{\circ}C$, ${\alpha}-MEM$ had the highest preserving ability of periodontal ligament cells, while that of P-milk, HBSS, S-milk, tap water was low in order. 3. Among the storage media at $37^{\circ}C$, the preserving ability of periodontal ligament cells was very high in ${\alpha}-MEM$, P-milk, HBSS and S-milk, it's lowest in tap water. 4. The preserving ability of periodontal ligament cells in ${\alpha}-MEM$ was high at $4^{\circ}C$ and it's low in order of $25^{\circ}C$, $37^{\circ}C$, but in HBSS was high at $4^{\circ}C$ and it's low at $25^{\circ}C$, $37^{\circ}C$ 5. The preserving ability of periodontal ligament cells in S-milk and P-milk was high at $4^{\circ}C$, $25^{\circ}C$ and it s low at $37^{\circ}C$. In conclusion, HBSS is the storage medium of choice in an avulsion, but in this study it is preferable to choose milk at $4^{\circ}C$ for tooth since it is easy to get and affect cell viability.

• Microbiology and Biotechnology Letters
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• v.37 no.3
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• pp.204-212
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• 2009

A strain producing ${\alpha}$-galactosidase and ${\beta}$-glucosidase was isolated from Kimchi. The isolated strain was identified as Weissella cibaria by 16S rDNA analysis and designated as Weissella cibaria K-M1-4. The enzyme activity of ${\alpha}$-galactosidase and ${\beta}$-glucosidase reached the maximum in the soy medium at $37^{\circ}C$ for 24 hr. The enzymes were purified by ethanol fractionation, DEAE sepharose fast flow, and sephacryl S-100HR column chromatography. ${\alpha}$-Galactosidase specific activity was shown by 576 Units/mg protein and the yield was 3.5% of the total activity of crude extracts. ${\beta}$-glucosidase specific activity was shown by 480 Units/mg protein and the yield was 2.9% of the total activity of crude extracts. The optimum temperature for ${\alpha}$-galactosidase was $60^{\circ}C$ and 43% of its original activity remained when it was treated at $80^{\circ}C$ for 30 min. For ${\alpha}$-galactosidase shows the optimum pH of 8.0 and is fairly stable between pH5.0 and pH9.0. The enzyme activity was increased in the presence of $Fe^{2+}$ and $Cu^{2+}$. The value of Km and Vmax for the enzyme were 0.98 mM and $1.81{\mu}$mole/min, respectively. The ${\beta}$-glucosidase has the optimum temperature of $50^{\circ}C$ and 46% of its original activity remained when it was treated at $80^{\circ}C$ for 30min. Its optimum pH of 7.0 and is fairly stable between pH5.0 and pH9.0. The enzyme activity was increased in the presence of $Fe^{2+},\;Co^{2+}$ and $Cu^{2+}$. The value of Km and Vmax for the enzyme were 1.24 mM and $6.81{\mu}$mole/min, respectively.

• Economic and Environmental Geology
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• v.42 no.3
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• pp.177-193
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• 2009

The Samgwang deposit consists of eight massive mesothermal quartz veins that filled NE and NW-striking fractures along fault zones in Precambrian granitic gneiss of the Gyeonggi massif. The mineralogy and paragenesis of the veins allow two separate discrete mineralization episodes(stage I=quartz and calcite stage, stage II-calcite stage) to be recognized, temporally separated by a major faulting event. The ore minerals are contained within quartz and calcite associated with fracturing and healing of veins that occurred during both mineralization episodes. The hydrothermal alteration of stage I is sericitization, chloritization, carbonitization, pyritization, silicification and argillization. Sericitic zone occurs near and at quartz vein and include mainly sericite, quartz, and minor illite, carbonates and chlorite. Chloritic zone occurs far from quartz vein and is composed of mainly chlorite, quartz and minor sericite, carbonates and epidote. Fe/(Fe+Mg) ratios of sericite and chlorite range 0.45 to 0.50(0.48$\pm$0.02) and 0.74 to 0.81(0.77$\pm$0.03), and belong to muscovite-petzite series and brunsvigite, respectiveIy. Calculated $Al_{IV}$-FE/(FE+Mg) diagrams of sericite and chlorite suggest that this can be a reliable indicator of alteration temperature in Au-Ag deposits. Calculated activities of chlorite end member are $a3(Fe_5Al_2Si_3O_{10}(OH)_6$=0.0275${\sim}$0.0413, $a2(Mg_5Al_2Si_3O_{10}(OH)_6$=1.18E-10${\sim}$7.79E-7, $a1(Mg_6Si_4O_{10}(OH)_6$=4.92E-10${\sim}$9.29E-7. It suggest that chlorite from the Samgwang deposit is iron-rich chlorite formed due to decreasing temperature from high temperature(T>450$^{\circ}C$). Calculated ${\alpha}Na^+$, ${\alpha}K^+$, ${\alpha}Ca^{2+}$, ${\alpha}Mg^{2+}$ and pH values during wallrock alteration are 0.0476($400^{\circ}C$), 0.0863($350^{\circ}C$), 0.0154($400^{\circ}C$), 0.0231($350^{\circ}C$), 2.42E-11($400^{\circ}C$), 7.07E-10($350^{\circ}C$), 1.59E-12($400^{\circ}C$), 1.77E-11($350^{\circ}C$), 5.4${\sim}$6.4($400^{\circ}C$), 5.3${\sim}$5.7($350^{\circ}C$)respectively. Gain elements(enrichment elements) during wallrock alteration are $TiO_2$, $Fe_2O_3(T)$,CaO, MnO, MgO, As, Ag, Cu, Zn, Ni, Co, W, V, Br, Cs, Rb, Sc, Bi, Nb, Sb, Se, Sn and Lu. Elements(Ag, As, Zn, Sc, Sb, Rb, S, $CO_2$) represents a potential tools for exploration in mesothermal and epithermal gold-silver deposits.

• Journal of the Korean Ceramic Society
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• v.35 no.4
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• pp.330-330
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• 1998

Active belite cement clinkers were synthsized by using natural raw materials with borax and calcium phosphate ({{{{ {Ca }_{3 }( {PO}_{4}) }}2) In both case {{{{alpha ^、 {C }_{2 }S }} were formed but borax was more efficient. The cement syn-thesized with the addition of borax was hydrated with the addition of anhydrite(5 wt%) and slag(30wt%, 40wt% 50wt%) The addition of 50wt% slag with anhydrite was good for strength development in 7days and the compressive strength was developed to twice than no addition of slag at 28 days strength.

• Korean Journal of Food Science and Technology
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• v.16 no.4
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• pp.463-471
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• 1984

For the eventual alcohol production from uncooked starch, an efficient saccharification process was examined by using the combined action of steeping, pectin depolymerase, ${\alpha}-amylase$ and glucoamylase. The total sugar content of rice, sweet potato and tapioka used were 4.53, 4.26, and 3.92 mmole/g sample. $70\;{\pm}\;10%$ of the total sugar was hydrolyzed when cooked starch was saccharified under the condition which is currently used in industry. The smaller starch particle was used, the more saccharification was obtained. Efficient saccharification was obtained by treatment with 5% $H_2SO_4$ (sample: working volume = 1:2) at $60^{\circ}C$ for 12 hr. Optimization was carried out for the saccharification of uncooked starch by the combined action of pectin depolymerase, ${\alpha}-amylase$, and glucoamylase. The conditions are: pectin depolymerase; pH 4.5, $45^{\circ}C$, 2 hr, ${\alpha}-amylase$; pH 6.0, $60^{\circ}C$, 1 hr, and glucoamylase; pH 3.5, $60^{\circ}C$, 1 hr. Simultaneous treatment of the combined action of macerating, liquifying and saccharifying enzymes yielded better result than stepwise treatment of 3 enzymes. Degrees of saccharification of uncooked tapioka, rice and sweet potato were 82, 90.5, and 84.5%, respectively on the basis of total sugar, under the optimized conditions.