• Korean Journal of Materials Research
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• v.8 no.3
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• pp.219-223
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• 1998

Spectroscopic properties of $Eu^{3+}$, $Sm^{3+}$, $Tb^{3+}$ ions in silicate glasses have been studied. The absorption and emission properties were investigated with the wavelength and rare-earth element concentration. The results showed that the emission spectrum of $Sm^{3+}$ was a transition from $^{5}D_{o}$ excited level to ^{7}F$ ground state and $Sm^{3+}$ was from $4F_{5/2}$ to $^{6}H$ and $Tb^{3+}$ was from $^{5}D_{4}$ to ^{7}F$ The emission intensity was linearly increased with rare-earth element concentrations up to 10wt%.

• KSBB Journal
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• v.11 no.6
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• pp.712-717
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• 1996

Cellulase was modified with synthetic copolymers of polyoxyethylene derivative and maleic acid anhydride. The saccharification characteristics and enzymatic reaction kinetic mechanism of modified and native cellulases were observed. In modification reaction of cellulase, degree of modification(DM) increased, as mass ratio of copolymers to enzyme increased. Maximum DM was 55% at mass ratio of 4 and remained activity was 75%. In saccharification experiment modified enzyme had maintained higher stability than native enzyme over all the reaction and the final conversion yield of modified enzyme was greater than that of native enzyme. Numerical simulation based on the reaction mechanism considering enzymatic deactivation was performed. Modified enzyme had kept higher free enzyme concentration over all the reaction than that of native enzyme. Comparing calculation values with experimental data, calculation values were in accordance with experimental data.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.747-751
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• 2008

The effect of additives in the synthesis of biodiesel fuel using supercritical methanol was studied in order to examine the possibility of application of spent vegetable oil as a raw material, which has high contents of water or free fatty acid. The experiments were performed by varying the contents of water, free fatty acid or antioxidants respectively in a batch reactor. The contents of fatty acid methyl ester was analyzed by a gas chromatography. As the water contents increased, the contents of fatty acid methyl ester decreased, however, the decrease was very little compared with the alkaline and acid catalyst. The effect of the contents of free fatty acid, vitamin E, and ${\beta}$-carotene was negligible.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.6
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• pp.693-698
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• 1997

Drought resistance and salt resistance of seedlings were compared with the polyethylene glycol(P.E.G) and NaCl solutions of the same osmotic potential($\Psi_\pi$=-10 bar). Plant height, seedling dry weight, chlorophyll content and leaf water potential decreased while the free proline content increased more in the P.E.G. than in the NaCl solution. Free amino acids increased 2.6 times in the P.E.G. solution and 3.6 times in the NaCl solution more than in the untreated(Hoagland's solution). Free proline occupied 66% and 61% of the content of total amino acids under water stress and salt stress, respectively. Besides free proline, phenylalanine in the P.E.G. solution and phenylalanine, alanine and asparagine in the NaCl solution increased distinctly. In short, it was shown that water and salt stress responses in seedling stage were relatively similar.

• Reproductive and Developmental Biology
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• v.28 no.2
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• pp.89-94
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• 2004

This study was conducted to determine expression of acyl-CoA synthetase 4(ACS4), which is involved in converts arachidonic acid to postaglandins, in the mouse uterus during pregnancy. In arachidonic acid metabolism, acyl-CoA synthetase plays a key role in the esterification of free arachidonic acid into membrane phospholipids. Following its release by the action of calcium dependent phospholipases, free arachidonic acid is believed to be rapidly converted to arachidonoyl-CoA and reesterified into phospholipids in order to prevent excessive synthesis of prostaglandins. Here we demonstrate that ACS4 gene are differentially regulated in the peri-implatation mouse uterus. During the preimplantation period(days 0.5∼3.5), the ACS4 gene was expressed in the uterus until day 3.5 after which the expression was downregulated. The expression of cPLA2, COX1, and COX2 gene was similar to that of ACS4 gene in the preimplantation periods. However expression levels of COX1 gene show much variation on the various days of pregnancy examined. These data, suggest that ACS4 expression in preimplantation period is involved in initial attachment reaction with cPLA2, COX1, and COX2 gene.

• The korean journal of orthodontics
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• v.28 no.3 s.68
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• pp.399-407
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• 1998

In order to resolve enamel demineralization around orthodontic bracket, fluoride-releasing materials, glass ionomer cements and fluoride-containing resin, were introduced in orthodontic department. There were many studies about their fluoride release, but their results were controversial. The purpose of this study was to clarify the pattern and amounts of fluoride release from glass ionomer cements and a fluoride-containing resin during 70 days in vitro. Disc shaped specimens were prepared and immersed in polyethylene tube containing 2ml distilled deionized water. The daily amounts of the fluoride released from each specimens were measured after experiment 1 day, 3 days, 7 days, 14 days, 42 days and 70 days. They were measured by fluoride-specific electrode combined pH/Ion meter. The following results were as follow, 1. Fluorides released from fluoride-containing resin during 1 day were significantly less than those from glass ionomer cements. 2. On experiment 70 days, mean daily amounts of fluoride released from Miracle-$Mix^{\circledR}$were $3.4{\mu}g/cm^2$, those from Fuji GC $II^{\circledR}$ were $2.7{\mu}g/cm^2$, those from $Orthobond^{\circledR}$ were $2.3{\mu}g/cm^2$, those from Fuji GC $LC^{\circledR}$were $1.4{\mu}g/cm^2$ and those from fluoride-containing resin, $Heliomolar^{\circledR}$, were $0.1{\mu}g/cm^2$. 3. There were no significant differences in daily amounts of fluoride released from between self-curing glass ionomer cements and light-curing glass ionomer cements. Amounts of released fluoride varied among commercially available products. 4. In all experimental materials, amounts of released fluoride decreased rapidly until experimental 3 days and then decreased slowly until 14 days and more slowly until 70 days.

• Journal of Ginseng Research
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• v.10 no.1
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• pp.80-93
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• 1986

The tail portion of dried 6-year old white ginseng was extracted and sugars and nitrogen compounds were also evaluated for chemical properties depending on varying conditions of extractions. The factors studied were extraction temperature in the range of 70-$100^{\circ}C$, ethanol concentration of 0-90% and the times of extractions which was taken 8 hours per each extraction in water at $80^{\circ}C$. For the effect of ethanol concentration in the extraction solvent, it was found that the amounts of free, reducing and total sugars and starch recovered in extract were almost linearly decreased along with the increase of concentration and the nonprotein nitrogen accounted over 84% of total nitrogen in extract. As ethanol concentration became increased, extractions of total nitrogen and water souluble nonprotein nitrogen were decreased especially in 90% ethanol. For the extraction temperature, all the sugar fractions with water and 70% ethanol except free sugar have tended to increase along with the temperature raised from 70 to $100^{\circ}C$ and it was found there is little changes of nitrogen compounds in the temperature range except a rapidly increase in water soulble protein at $100^{\circ}C$. For the times of extractions, showed that most of extractable compounds were extracted in 3 times of extractions with water at $80^{\circ}C$. It was shown that more than 95f) of sugars and 80% of nitrogen compounds were yielded with water extraction. Accordingly it was efficient to extract with water or 70% ethanol in 3 times in terms of !actor and energy consumption.

• The Korean Journal of Pharmacology
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• v.27 no.2
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• pp.125-133
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• 1991

In the isolated rabbit mesenteric artery denuded of endothelium, we characterized the identity of the A23187-induced endothelium-dependent relaxing factor (EDRF) released from the endothelium of rabbit aorta, which is distinct from that of acetylcholine-induced relaxing factor. In the normal physiological salt solution (PSS), the dose-response curves to A23187 and acetylcholine were overlapped together. Their effects were also inhibited by methylene blue. Upon application of hypoxanthine and xanthine oxidase into the bath, the phenylephrine-induced precontraction was transiently increased followed by the sustained relaxation. During the burst of hypoxanthine-xanthine oxidase reaction, the $Ca^{++}$ ionophore, A23187 but not acetylcholine was able to cause an immediate relaxation. However, A23187-induced relaxation was not manifested when precontracted by 50 mM $K^+-PSS$. Nevertheless, in the presence of superoxide dismutase, A23187 could produce an immediate relaxation without accompanying the transient contraction as acetylcholine did during the hypoxanthine-xanthine oxidase reaction. On the other hand, acetylcholine-induced relaxation was more sensitively inhibited by phorbol 12-myristate 13-acetate (PMA) than A23187-induced relaxation. Endothelium-independent relaxation to sodium nitroprusside was not affected by PMA. Based on these results it is suggested that both A23187 and acetylcholine cause the methylene blue-inhibitable endothelium-dependent relaxation, and in addition, A23187 may release a stable EDRF which is resistant to superoxide anion and PMA.

• Korean Chemical Engineering Research
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• v.53 no.6
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• pp.792-797
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• 2015

Graphene has a wide spectrum on its application field due to various and excellent physical properties. However, it is very difficult to apply that graphene exists as lump or fold condition in general organic solvents. Besides, graphene was difficult to maintain as uniform condition due to chemical inert and distributions with various size and shapes. Therefore, this study was focused to study dispersion and modifying methods of aggregated graphene. The dispersion methods contain as follow: i) physical milling using glass bead, ii) co-treatment of glass bead and ultrasonic waves, iii) dispersion in organic solvents, iv) modifying with dry-ice. Milling using glass bead with size 2.5 mm was effective to be size decrease of 36.4% in comparison with control group. Mixed treatment of glass bead (size 2.5 mm) and ultrasonic waves (225W, 10 min) showed relative size decrease of 76%, suggesting that the size decrease depends on the size of glass bead, intensity of ultrasonic waves and treatment time. Solvents of Ethyl acetate (EA) and Isoprophyl alcohol (IPA) were used in order to improve dispersion by modifying surface of graphene. IPA of them showed a favorable dispersion with more -CO functional groups in the FT-IR analysis. On the other hand, the oxygen content of graphene surface modified by dry-ice was highly increased from 0.8 to 4.9%. From the results, it was decided that the favorable dispersion state for a long time was obtained under the condition of -CO functional group increase in IPA solvent.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.1
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• pp.48-52
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• 1993

To furnish basic data for the utilization of leaf mustard as a raw material of salted and fermented vegetable food, major chemical compositions of Dolsan Leaf Mustard (DLM) were investigated. The moisture and ash contents of DLM were 87.5% and 1.4%, respectively. Compared with other Korean traditional or Japanese leaf mustard, DIM contained more crude protein (3.8%) but less crude fat (0.3%) and crude fiber (1.3%). As an alkali food, leaf and leat stalk had pH of 5.7 and 5.8, titratable acidity of 687 and 318mg/100g and alkalinity of 2.5 and 5.2, respectively. The major free sugar in DLM was glucose and fructose was also detected in a small amount. The contents of total and reducing sugar in leaf and leaf stalk were 574, 352, 820 and 538mg%, respectively. Total amino acid contents of leaf and leaf stalk were 8.0 and 2.5% on wet basis. Although the amino acid compositions of leaf and leaf stalk were different each other, glutamic acid and proline were the major amino acids in both of the leaf and leaf stalk. Significantly higher amount (ca.10.3-fold) of free amino acid was present in leaf (3074mg%) than in leaf stalk (298mg%). Glutamic acid and aspartic acid were the major free amino acids and essential amino acid contents in leaf and leaf stalk were 869 and 68mg% being 22.9 and 28.3% of total free amino acids.