• Korean Membrane Journal
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• v.4 no.1
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• pp.25-35
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• 2002

The gas permeation properties have been studied on carbon molecular sieve (CMS) membranes prepared by pyrolysis of P84 polyimide under various conditions. P84 polyimide shows high permselectivities (O$_2$/N$_2$= 9.17 and CO$_2$/N$_2$= 35) for various gas pairs and has a good processibility because it is easily soluble in high polar solvents such as N-methylpyrrolidinone (NMP), dimethylformamide (DMF), and N,N-dimethylacetamide (DMAc). After pyrolysis under Ar flow, the change in the heating rate was found to affect the gas permeation properties to some extent. The permeabilities of the selected gases were shown to be in the order He ＞ CO$_2$＞ O$_2$＞ N$_2$for all the CMS membranes, whose order was in accordance with the order of kinetic gas diameters. It also revealed that the pyrolysis temperature considerably influenced the gas permeation properties of the CMS membranes derived from P84 polyimide. The CMS membranes pyrolized at 700$\^{C}$ temperature exhibited the highest permeability with relatively targe loss in permselectivity. This means that the pyrolysis temperature should be varied in accordance with target gases to be separated.

• Bulletin of the Korean Chemical Society
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• v.17 no.2
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• pp.173-179
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• 1996

A series of tetradentate Schiff base ligands; [1,2-bis(naphthylideneimino)ethane, 1,3-bis(naphthylideneimino)propane, 1,4-bis(naphthylideneimino)butane, and 1,5-bis(naphthylideneimino)pentane] and their Ni(Ⅱ) complexes have been synthesized. The properties of these ligands and their Ni(Ⅱ) complexes have been characterized by elemental analysis, IR, NMR, UV-vis spectra, molar conductance, and thermogravimetric analysis. The mole ratio of Schiff base to Ni(Ⅱ) metal was found to be 1:1. The electrochemical redox process of the ligands and their Ni(Ⅱ) complexes in DMF and DMSO solution containing 0.1 M tetraethyl ammonium perchlorate (TEAP) as a supporting electrolyte have been investigated by cyclic voltammetry, chronoamperometry, differential pulse voltammetry, and controlled potential coulometry at glassy carbon electrode. The redox process of the ligands was highly irreversible, whereas redox process of Ni(Ⅱ) complexes were observed as one electron transfer process in quasi-reversible and diffusion-controlled reaction. The electrochemical redox potentials of the Ni(Ⅱ) complexes were affected by the chelate ring size of ligands. The diffusion coefficients of Ni(Ⅱ) complexes containing 0.1 M TEAP in DMSO solution were determined to be 5.7-6.9 × 10-6 cm2/sec. Also the exchange rate constants were determined to be 1.8-9.5 × 10-2 cm2/sec. These values were affected by the chelate ring size of ligands.

• Journal of Korean society of Dental Hygiene
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• v.3 no.1
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• pp.13-24
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• 2003

The researcher worked with a total of 158 high school girls visiting the scaling practice room at the department of dental hygiene in Jinju Health college from November 11, 2002 to December 4, 2002, having their teeth scaled, observing their teeth and interviewing them with the aid of questionnaires. The findings can be summarized as follows. 1. The survey on the understanding of dental health and the attitudes of the subjects shows the following results : "I have never learned how to brush teeth" (65.8%: 104 girls); "I brush my teeth twice a day" (57.0%: 90 girls) : "I brush my teeth for 2 minutes"(44.3%: 70 girls): "I brush my teeth vertically and horizontally" (53.2%: 84 girls): "( brush my teeth, gum and tongue" (462%: 73 girls): "I use one brush for two months" (40.5%: 64 girls); "I don't have any floss" (582%: 92 girls): "I have never had my teeth scaled" (84.2%: 133girls) : "Smoking is bad for the teeth" (77.8%: 123 girls): "Drinking is bad for the teeth" (48.7%: 77 girls): "I have ever visited dental clinics" (92.4%: 146 girls). 2. The study on part of the teeth most exposed to caries shows the following results : Mandibular right first molar(79.8%: 126 girls): Mandibular left first molar(77.5%: 124 girls), Mandibular left second molar(70.2%: 111 girls). Mandibular right second molar(65.7%: 104 girls). Maxillary left first molar(59.5%: 94 girls): Maxillary left second molar(59.5%: 94 girls): Maxillary right first molar(58.2%: 92 girls). Maxillary right second molar(50.7%: 80 girls) 3. The statistics on the subjects' caries show the following results: DMF rate: 943%: DMFT rate: 25.61%: DMFT index: 7.17 teeth : DT rate: 4651%: FT rate: 52.25%: MT rate: 124% 4. The survey on dental caries statistics, dental health, dental health behavior, and the subjects' attitudes shows the following results: The worse the subjects' dental health was(r=-327, p<.001), the more they visited dental clinics(r=.195, p<.05), the higher DMT rate, DMFT index were; The more the subjects visited dental clinics(r =.359, p<.001), the higher DT rate was; The worse the subjects teeth went(r=-.197, p<.05), the higher MT rate was. It is necessary that systematic and substantial dental health education for high school students should be carried out in regard to plaque control, fluoride application, diet control, pit & fissure sealant as a part of developing national health policies designed for the dental health of the teenagers.

• Journal of the Korean Chemical Society
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• v.26 no.4
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• pp.235-246
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• 1982

The free radical polymerization and copolymerization of N-acetyl ${\alpha}$-aminoacrylic acid were investigated. From the result of kinetic investigation of N-acetyl ${\alpha}$-aminoacrylic acid in DMF at $60^{\circ}C$, a rate equation of $R_p$ = $k_p[M]^{0.97}[I]^{0.59}$ was obtained. The overall activation energy for the polymerization was found to be 25.2 kcal/mole. Copolymerization of N-acetyl ${\alpha}$-aminoacrylic acid with acrylic acid and styrene was carried out for the determination of monomer reactivity ratios. The monomer reactivity ratios for the monomer pairs determined at 70.0{\pm}0.1^{\circ}C$ using benzoyl peroxide as an initiator are; $r_1$(N-acetyl ${\alpha}$-aminoacrylic acid) = 0.49, $r_2$(acrylic acid) = 1.41, $r_1$(N-acetyl ${\alpha}$-aminoacrylic acid) = 0.44, $r_2$(styrene) = 0.91. The values of Alfrey-Price's Q and e parameters for N-acetyl ${\alpha}$-aminoacrylic acid were calculated to be 0.51 and 0.16 for the both systems. Differential thermal analysis and thermogravimetry showed that acrylic acid copolymers have poorer thermal stability as compared with the homopolymer of N-acetyl ${\alpha}$-aminoacrylic acid.

• Korean Journal of Environmental Agriculture
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• v.11 no.2
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• pp.146-154
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• 1992

DDVP, malathion and diazinon ECs which differ in chemical compositions and moisture contents were formulated with nine emulsifiers, three solvents(xylene, cyclohexanone and DMF) and epichlorohydrin. For the studies of decomposition characteristics, these technicals and ECs were subjected to the test under elevated temperature at $54^{\circ}C$ for 15 days and $38^{\circ}C$ for 90 days respectively. DDVP technical was rapidly decomposed in early stage of thermoaccelerated test at $54^{\circ}C$, but the decomposition rate slowed down with time. As for malathion and diazinon technicals, the longer they were incubated, the more decomposed. The decomposed AI in ECs increased with solvent polarity. The increment of moisture content in ECs accelerated the decomposition of AI, and that was remarkable especially in diazinon ECs. Addition of emulsifiers increased the moisture content to be accelerated the decomposition of AI, but the decomposition of AI was more affected by the kind of emulsifier than by the moisture content of emulsifier, Stabilizing effect by epichlorohydrin was distingished in malathion and diazinon ECs, but there was no effect in other solvent-based formulation except xylene.

• Food Science and Preservation
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• v.11 no.4
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• pp.496-502
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• 2004

Purified acorn starch was obtained from alkali precipitation method. Acorn amylose and acorn amylopectin were fractionated from purified acorn starch by butanol improvement method. Gel permeation chromatography (GPC) was used to measure molecular weight distribution of acorn starch, acorn amylose, acorn amylopectin and corn starch, corn amylose, corn amylopectin. GPC measurement diagrams were obtained by each retention time. And then, we used DMSO and DMF as solvent, pullulan as standard material. We calculated the Number-average molar mass (Mn), Weight-average molar mass (Mw) and polydispersity from molecular weight distribution of each sample. As a result of estimating molecular weight using GPC, Mw of amylose has small value than Mw of amylopectin. From this fact, the molecular structural aspects of amylose and amylopectin were predicted and it was in good agrement with the tendency of polydispersity by GPC. The polydispersity of starch had big value than amylose and amylopectin, from this result, it might be known that the range of molecular weight appeared broad by heterogeneous properties of two components. The viscosity of purified acorn starch, amylose, amylopectin seperated from acorn starch, was decreased by increasing the shear rate and raising the temperature exponentially. Acorn starch solutions exhibited pseudoplastic power law fluid behavior.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.427-427
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• 2016

Organic-inorganic hybrid perovskite have attracted significant attention as a new revolutionary light absorber for photovoltaic device due to its remarkable characteristics such as long charge diffusion lengths (100-1000nm), low recombination rate, and high extinction coefficient. Recently, power conversion efficiency of perovskite solar cell is above 20% that is approached to crystalline silicon solar cells. Planar heterojunction perovskite solar cells have simple device structure and can be fabricated low temperature process due to absence of mesoporous scaffold that should be annealed over 500 oC. However, in the planar structure, controlling perovskite film qualities such as crystallinity and coverage is important for high performances. Those controlling methods in one-step deposition have been reported such as adding additive, solvent-engineering, using anti-solvent, for pin-hole free perovskite layer to reduce shunting paths connecting between electron transport layer and hole transport layer. Here, we studied the effect of alkali metal halide to control the fabrication process of perovskite film. During the morphology determination step, alkali metal halides can affect film morphologies by intercalating with PbI2 layer and reducing $CH3NH3PbI3{\cdot}DMF$ intermediate phase resulting in needle shape morphology. As types of alkali metal ions, the diverse grain sizes of film were observed due to different crystallization rate depending on the size of alkali metal ions. The pin-hole free perovskite film was obtained with this method, and the resulting perovskite solar cells showed higher performance as > 10% of power conversion efficiency in large size perovskite solar cell as $5{\times}5cm$. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma optical emission spectrometry (ICP-OES) are analyzed to prove the mechanism of perovskite film formation with alkali metal halides.

• Journal of Korean society of Dental Hygiene
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• v.10 no.3
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• pp.465-471
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• 2010

Objectives : This study was conducted to purpose the fundamental data for further developments of the school dental clinic program(SDCP) through comparing results of oral health promotion program for 4 years relating to compare oral health status of children who had experienced and had not experienced the program. Methods : The subjects were 66 children of elementary school in Busan Metropolitan City who had benefited school dental clinic program(SDCP) from 2004 to 2007 and control group was 98 children of elementary school who had not benefited school dental clinic program(SDCP). Data analysis were done with SPSS program (ver 13.0) through basic statistical data, t-test. Results : The DMF rate of elementary school students who had benefited program was 41.5% and it was lower than that of control group(52.5%), however it was not significant statistically. The DMT index of elementary school students who had benefited program was 1.81 and it was lower than that of control group(2.44)(p<0.05). The DMFT rate of elementary school students who had benefited program was 4.44% and it was lower than that of control group(7.45%)(p<0.05). Conclusions : In oder to promote oral health of children, school dental clinic in elementary school should be extended to more elementary schools as possible and the operating system should be changed to improve the efficiency. Oral health educational materials should be developed and utilized to improve educational effect.

• Journal of Nutrition and Health
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• v.19 no.5
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• pp.315-322
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• 1986

The food habits and health complaints were studied for 459 persons, 60 years and over, in the rural area, JKurye-Gun Chonnam, from April 28 to May 1, 1986. by the questionnaire sheets ; one was for the food habits, and the other was for health complaints(the standarized questionnair designed in Todai Health Index). The results obtained were as follows. 1) Mean score of the food habit was 11.2$\pm$3.5 in male and 10.8$\pm$2.9 in female. The score in both sexes showed a falling tendency as their ages increased. 2) THI scores in surfferings eye & skin, mouth & anus were higher (p<0.01, p<0.05, p<0.01) in female than in male. As age increased, the THI score showed a rising tendency. In case of male, THI socre in digestive organs was higher (p<0.05) in sixties than in other age. 3) The rate of living together with their family or spouse in the male aged was 77% higher than in the female aged. whilte the rate of celibacy in the female aged was 28%, higher than 3% in the male aged. DMF value was higher in female than male. The amount of alcohol ingestion were 2.1 and 0.6 Cup in male and female, respectively and the amount of smoking were 10.5 and 3.1 cigarettes in male and female respectively. Both alcohol intake and smoking were higher in male(p<0.01) 4) In case of male, the correlation coefficient between the score of food habit and THI score was negative in suffering eye & skin, mouth & anus, respectively, and in female it was negative in digestive, mouth & anus. As the score of food habit become low, the THI score become high. 5) Those living alone in both sexes showed a low score in food habit.

• Journal of the korean academy of Pediatric Dentistry
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• v.3 no.1
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• pp.52-62
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• 1976

The purpose of this paper is to present the clinical findings obtained from the fourth year epidemiological study on dental caries prevalence in Korean children and to compare them with those from the first year study made in 1973 by Paik. The oral examination was performed for this study on 1,451 children, composed of 808 boys and 643 girls, at "K" elementary school located in Seoul, Korea. The following conclusions are drawn: 1. The df person rate of primary teeth is 90.30% for boys, 90.67% for girls, and 90.43% for all, which is 7.41% higher than the first year value. 2. The dft index per child of primary teeth is 4.26 for boys, 4.30 for girls, and 4.28 for all, which is 0.42 higher than the first year value. The dt index is 2.49 for boys, 2.44 for girls, and 2.47 for all, which is 0.59 lower than the first year value. The ft index is 1.77 for boys, 1.86 for girls, and 1.81 for all, which is 1.01 higher than the first year value. 3. The DMF person rate of permanent teeth is 70.24% for boys, 73.05% for girls, and 71.49% for all, which is 16.28% lower than the first year value. 4. The DMFT index per child of permanent teeth is 2.08 for boys, 2.50 for girls, and 2.27 for all, which is 1.31 lower than the first year value. The DT index is 1.44 for boys, 1.64 for girls, and 1.53 for all, which is 1.53 lower than the first year value. The FT index is 0.61 for body, 0.85 for girls, and 0.71 for all, which is 0.21 higher than the first year value. The MT index is 0.02 for all, which is statistically the same as the first year value.