• Food Science and Preservation
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• v.6 no.4
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• pp.495-499
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• 1999

The free sugars in leaf and root of dandelion were composed of sucrose, glucose and fructose. The contents of total free sugars was higher in root than those in leaf. The oxalic acid, citric acid and malic acid contents of leaf was 45.4, 3.6, 2.7mg/100g-f.w., respectively. And the oxalic acid, citric acid and malic acid contents of root was 34.6, 2.1, 1.6mg/100g-f.w., respectively. Total free organic acid content of leaf was higher than that of root. The major free amino acids of dandelion were aspartic acid, serine, asparagine, glutamic acid, glycine, valine, isoleucine and content of glutamic acid was highest in free amino acids. The contents of vitamin A in leaf and root of dandelion was 135.4 and 34.1$\mu\textrm{g}$/100g-f.w., respectively. The contents of vitamin C in leaf and root of dandelion was 67.4 and 4.6 mg/100g-f.w., respectively.

• Journal of the Korean Chemical Society
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• v.42 no.3
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• pp.315-322
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• 1998

A series of new dimesogenic compounds were prepared and their thermotropic and liquid crystalline properties were studied by differential scanning calorimetry and on a hot-stage of a polarizing microscope. These compounds, 1,10-bis[2,5-bis(4-substitutedphenoxycarbonyl)phenoxy]decanes, consist of two bis(ρ-substitutedphenoxy)terephthalate units interconnected through a oxydecamethyleneoxy spacer on the central terephthaloyl units resulting in the structure of "H-shaped" dimeric twin compounds. The terminal substitutent groups were changed; X=-F, -H, -I, -Cl, -Br, $-NO_2,\;-CF_3,\;-OC_4H_9,\;-CN\;and\;-C_6H_5.$ The compounds with X=$-OC_4H_9,\;-CN\;and\;-C_6H_5$ were monotropically nematic. In contrast, the compounds with $X=-F, -H, -I, -Cl, -Br, $-NO_2\;and\;-CF_3$ were non-liquid crystals. The nematic group efficiency of these compounds was in the order of -C_6H_5>-CN>-OC_4H_9.$

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1211-1215
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• 1999

Fluorinated amorphous carbon (a-C:F) films were prepared by an electron cyclotron resonance chemical vapor deposition (ECRCVD) system using a gas mixture of $C_2F_6$ and $CH_4$ over a range of deposition temperature (room temperature ~ 300$^{\circ}C$). 500$^{\AA}C$ thick DLC films were pre-deposited on Si substrate to improve the strength between substrate and a-C:F film. The chemical bonding structure, chemical composition, surface roughness and dielectric constant of a-C:F films deposited by varying the deposition temperature were studied with a variety of techniques, such as Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), atomic force microscopy (AFM) and capacitance-voltage(C-V) measurement. Both deposition rate and fluorine content decreased linearly with increasing deposition temperature. As the deposition temperature increased from room temperature to 300$^{\circ}C$, the fluorine concentration decreased from 53.9at.% down to 41.0at.%. The dielectric constant increased from 2.45 to 2.71 with increasing the deposition temperature from room temperature to 300$^{\circ}C$. The film shrinkage was reduced with increasing deposition temperature. This results ascribed by the increased crosslinking in the films at the higher deposition temperature.

• Electrical & Electronic Materials
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• v.9 no.9
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• pp.906-910
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• 1996

Ferroxplana N $i_{2}$Y(B $a_{2}$N $i_{2}$F $e_{12}$ $O_{22}$ ) magnetic particles, which is one of the hexagonal ferrite were synthesized by a coprecipitation method. The coprecipitates were prepared by adding aqueous solution of BaC $I_{2}$ - 2 $H_{2}$O, NiC $I_{2}$ - 6 $H_{2}$O and FeC $I_{3}$ - 6 $H_{2}$O(of which the mole ratio is $Ba^{+2}$ : N $i^{+2}$ : F $e^{3+}$= 1 : 1 : 6) to a mixture of NaOH and N $a_{2}$C $O_{3}$. The shape of Ferroxplana N $i_{2}$Y magnetic particles obtained at 1, 100(.deg. C) was hexagonal plate-like, average particle size and aspect ratio were 2(.mu.m) and 7, respectively.y.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.225-225
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• 2003

실리카글라스를 기초로 하는 PLC소자는 가격, 광 손실 성질과 광섬유와의 결합효율이 좋아 광통신에 응용되어지고 있으며 Ge 도핑된 실리카 글라스는 PLC소자의 코어물질로 널리 사용되고 있다. 소작제작을 위해서는 높은 식각률과 깨끗하고 적은 표면손상을 얻어야 하므로 유도결합플라즈마를 이용한 건식식각공정개발이 이루어 져야 한다. 본 연구에서는 Ge 도핑된 실리카글라스의 식각특성을 연구하기 위해 $C_2$F/6 와 NF$_3$가스를 사용하였고 ICP power, bias power, 압력, 플라즈마와 샘플간의 거리를 변화시키면서 식각속도, 표면거칠기, 메사수직도, 마스크선택도등 기본공정 조건을 연구하고 첨가가스(CH$_4$, $O_2$), 마스크 물질(Ni, Cr, PR) 도핑농도(0.3, 0.45, 0.7%)등을 변화시키면서 식각특성을 연구하였다. 그 결과 300nm/min, 정도의 식각속도를 가지고 수직한 메사각도(~89$^{\circ}$)와 미려한 표면(표면거 칠기 1.5nm 이하)를 갖는 결과를 얻었다.

• Microbiology and Biotechnology Letters
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• v.27 no.6
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• pp.466-470
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• 1999

Protease production and its characteristics were investigated with Mucor racemosus f. racemosus PDA 103 which was isolated from Korean traditional meju. Optimum culture conditions of the strain for the production of the protease in basic medium[bean(Baektae):H2O=1:1(w/v)] were as follows: pH 6, 3$0^{\circ}C$ and 72hrs. Optimum pH and temperature for the enzyme activity of the protease produced by Mucor racemosus f. racemosus were pH 5 and 5$0^{\circ}C$, respectively. The enzyme was relatively stable a pH2.0~5.0 and at temperature below 4$0^{\circ}C$. Phenylmethane-sulfonyl fluoride and Ag+ inhibited the enzyme activity. This indicates that the enzyme is serine protease. Km value was 0.9$\times$10-4M and Vmax value was 5.93$\mu\textrm{g}$/min. This enzyme hydrolyzed casein more rapidly than bovine albumin.

• Journal of Plant Biology
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• v.34 no.2
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• pp.113-119
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• 1991

The contents of reducing sugar, sucrose, starch and fructose-2,6-bisphosphate (F-Z,$6-P_2$) in relation to the activities of amylase, invertase and fructose-1,6-bisphosphatase (FBPase) were investigated from the leaves of rice (Oryza sativa L. cv. Samjin) seedlings grown at $4^{\circ}C$ for 3 days_ In the seedlings, the contents of reducing sugar and sucrose were increased, but soluble and insoluble starch were declined. Under this condition, amylase activity was increased. but acid invertase activity was declined and alkaline invertase activity was not changed. Cytosolic and stromal FBPase activities were increased. But F-2,$6-P_2$ content was declined. It seemed that the increase of reducing sugar content might be due to the increased activity of amylase and the increase of sucrose content might be related to the increased activity of cytosolic FBPase, reduced content of F-Z,$6-P_2$ and reduced rate of hydrolysis of sucrose during the cold treatment. These results suggested that the changes in carbohydrate rnetabolim of rice seedlings under low temperature reflect one of the protection mechanism to the low temperature during the cold treatment.atment.

• Bulletin of the Korean Chemical Society
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• v.16 no.6
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• pp.518-523
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• 1995

New square planar nickel(Ⅱ) complexes with various 1-alkyl (4a-4c) and 1-hydroxyalkyl (4d-4f) derivatives of the 14-membered pentaaza macrocycle 8-ethyl-8-nitro-1,3,6,10,13-pentaazacyclotetradecane have been synthesized by two-step metal template condensation reactions of ethylenediamine, nitroethane, formaldehyde, and appropriate primary amines. The nitro group and/or hydroxyl group of 4a-4f are not directly involved in the coordination. The nickel(Ⅱ) complexes exist in coordinating solvents such as MeCN, Me2SO, and H2O as equilibrium mixtures of the square planar [Ni(L)]2+(L=4a-4f) and octahedral species [Ni(L)S2]2+(S=solvent molecule). Although the ligand field strength and redox potentials of the complexes are not affected by the nature of the substituents, the formation of octahedral species for 4d-4f in MeCN is strongly restricted by the hydroxyl group. Synthesis, characterization, and solution behaviors of the nickel(Ⅱ) complexes are described.

• Journal of the Korean Ceramic Society
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• v.36 no.9
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• pp.946-953
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• 1999

The etching characteristics of Er-doped sodium borosilicate glass film for the planar optical waveguides were investigated using reactive ion etching. The etch rate decreased as the pressure in creased but increased as the RF power increased. The etch rate increased as the flow rate C2F gas and the amount of O2 addition increased but decreased over critical point (C2F6 7,5 accm O2 20%) The etch rate was 180${\AA}$/min under C2F6 7.5 sccm O2 20% RF power 270 W, pressure 150 mTorr. With this optimum etching condition and subsequent heat treatment at 975$^{\circ}C$ for 30 minutes planar optical waveguides having improved sidewall roughness were fabricated successfully.

• Textile Coloration and Finishing
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• v.11 no.1
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• pp.25-33
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• 1999

PET fabric was grafted with $CF_4$ or $C_2F_6$ plasmas generated by glow discharge. The water repellency of plasma-treated fabrics were evaluated with contact angle meter. The change in surface morphologies was observed by SEM, and the change of surface chemical characteristics were analyzed by FT-IR, ESCA and microchemical analysis technique. The results obtained are as follows : 1) The contact angle of plasma-treated fabric was over $150^\circ{C}$. 2) It was observed by SEM that the surface of treated substrate was over coated with thin film formed by the fluorocarbon plasma treatment. 3) According to ESCA analysis, there were prevailing -CHF-, $-CF_2$- and a little $-CF_3$ components on fluorocarbon plasma treated substrate. -CHF- and $-CF_2$- components were reduced by washing, and $-CF_2$- component was recovered by heat treatment. 4) In consideration of quantitative analysis of fluorine and F/C ratio by ESCA, we found that fluorination reached to the inner of substrate.