• Polymer(Korea)
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• v.30 no.3
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• pp.238-246
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• 2006

The aim of this study is to enhance the flame retardancy by the synergism effect of chlorine and phosphorus groups. The flame-retardant polyurethane coatings containing chlorine and phosphorus compounds were synthesized. After synthesizing the intermediate products of tetramethylene bis (orthophosphate) (TMBO) and neohexanediol trichlorobenzoate (TBA-adduct), the condensation polymerization was performed with four different monomers of two intermediates, 1,4-butanediol, and adipic acid to obtain four-component copolymer(TTBA). The two-component flame-retardant polyurethane coatings (TTBA-10C/HDI-trimer=TTHD-10C, TTBA-20C/HDI-trimer=TTHD-20C, TTBA-30C/HDI trimer=TTHD-30C) were obtained by curing reaction at room temperature with the synthesized TTBAs and hexamethylene diisocyanate (HDI)-trimer as a curing agent. The obtained TTHDs were made into coating samples and used as test samples for various physical properties. The physical properties of the flame-retardant coatings containing chlorine and phosphorus groups were generally inferior to those containing only phosphorus group. Flame retardancy was tested by vortical and horizontal combustion method, and $45^{\circ}$ Meckel burner method. Since the retardancy of flame-retardant coatings containing chlorine and phosphorus groups was better than that containing only phosphorus group, it could be concluded that the retardancy by the synergism effect of chlorine and phosphorus groups exhibited.

• Journal of dental hygiene science
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• v.14 no.2
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• pp.230-239
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• 2014

This study is to promote awareness to be exposed to radiation with identifying knowledge, attitudes and behavior for radiation safety management of the operating room nurse and dental hygienist. And the following results were obtained through questionnaire survey to deduct the education to prevent potential risks in advance and implication to be useful on education program. First, based on the level of knowledge for radiation safety management, 10.57 for dental hygienists, 9.55 for the nurse out of 15 points (p<0.001); based on the level of attitudes for radiation safety management, 4.64 for dental hygienists, 4.67 for the nurse out of 5 points (p<0.001); and based on the level of behavior for radiation safety management, 3.27 for dental hygienists, 2.93 for the nurse out of 5 points (p<0.001). Second, the result for checking the relation with knowledge, attitudes and behavior for radiation safety management, the knowledge of radiation safety management has correlation with attitudes and behavior for radiation safety management statistically (p<0.001).

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.605-613
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• 1992

NCO-terminated prepolymers were synthesized by reacting carbonate-type polyol(PTMCG)($M_w=1,000$ and 2,000) with MDI and N-methyldiethanolamine, as a chain extender. Carbonate-type polyurethane containg zwitterionic group was prepared by reacting the prepolymer with 1,3-propane sultone. From the IR and NMR spectra of model reactions, it was known that the ionization occurred under the same condition. The structure of zwitterionic carbonate-type polyurethane(ZPU) therefore could be confirmed from the model reactions. Glass transition temperature(Tg) ranged between $-15{\sim}-30^{\circ}C$ from the thermal data. Tg was between $-15{\sim}-18^{\circ}C$ for a series of ZPU10 samples and between $-25{\sim}-26^{\circ}C$ for a series of ZPU20 polymers. Tensile strength increased with mole ratio of ionic content. On the contrary, elongation was rather dropped with mole ratio of ionic content. ZPU10-30 having better tensile strength and less elongation was selected as a membrane for the concentration of ethanol aqueous solution through pervaporation. To obtain the better selectivity, it was crosslinked with HMDI. In the swelling test, it showed the higher swelling degree at around 50wt% ethanol concentration due to the plastization effect of ethanol. To optimize the separation capacity, two operating factors-feed concentration and temperature-were considered. The overall separation capacity was as follows : separation factor, 2~83.2 ; the flux, $25.4{\sim}58.8g/m^2hr$.

• Journal of Animal Science and Technology
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• v.45 no.1
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• pp.49-56
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• 2003

An experiment was conducted to study the effects of the dietary Cu sources on the performance of the weanling pigs. Forty-eight, 24 in each sex, 4 weeks old pigs were assigned to four treatments; control, methionine-Cu chelate, chitosan-Cu chelate or yeast-Cu chelate. Control diet contained 136ppm Cu to which additional 100ppm Cu in different chelated form was added to the respective treatment. Individual pig weight and feed intake of each pen were recorded weekly for 5 weeks. Average daily feed intakes(ADFI), average daily gains(ADG) and ADFI/ADG were not significantly different among treatments. Nutrient availability was not also significantly affected by treatments. Serum triglyceride concentration of chitosan-Cu treatment was significantly lower than those of methionine-Cu and yeast-Cu treatments but was not significantly different from that of the control. Serum cholesterol concentration of yeast-Cu was significantly lower than those of the control and methionine-Cu but was not significantly different from that of chitosan-Cu treatment. Serum HDL-cholesterol concentration was not significantly affected by treatments. Serum IgG concentrations of all copper treatments were significantly lower than that of the control. It was concluded that Cu-chelates supplemented to the basal diet (136ppm Cu) by the level of 100ppm Cu did not significantly affect growth performance of weaning pigs. However, serum parameters of cholesterol, cholesterol and IgG were significantly affected by the treatments.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.880-885
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• 2008

Spray pyrolysis was applied to prepare spherical silica particles with mesopores of a regular structure. The physical properties such as surface area, pore size, pore structure, particle size, and morphology were studied by BET, SEM, SAXS, and DLS analysis. At a fixed gas flow rate, the BET surface area changed from 200 to $1,290m^2/g$ as changing the CTAB/TEOS molar ratio from 0.05 to 0.3. At a fixed CTAB/TEOS ratio, the surface area of silica particles was varied from 1,062 to $1,305m^2/g$ with changing the gas flow rate from 10 to 40 l/min. The average pore size measured by BJH desorption was about $21{\sim}23{\AA}$ and not significantly influenced by the CTAB/TEOS ratio and the gas flow rate. Finally, the highest surface area which was $1,305m^2/g$ were obtained when the CTAB/TEOS ratio and the gas flow rate were 0.2 and 20 l/min, respectively. According to SAXS analysis, the prepared silica particles showed a strong peak at $2{\theta}=2.6^{\circ}$ and two minor peaks around $2{\theta}=4.4^{\circ}$ and $5.1^{\circ}$, which are due to regular mesopores of hexagonal structure. The morphology of silica particles prepared were spherical shape and the average particle size was $1.0{\mu}m$.

• Journal of dental hygiene science
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• v.18 no.4
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• pp.265-270
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• 2018

The purpose of this study was to investigate the chemical properties of some commercially available mouthwashes and to ascertain whether the mouthwashes accelerated mineral loss in dental enamel. Five commercially available mouthwashes were selected from the three largest malls in Korea: Perio Total 7 Aqua Cool Mint Strong $Fresh^{TM}$ (PS; LG Household & Health Care Ltd.), Garglin $Original^{TM}$ (Dong-A Pharmaceutical Co., Ltd.), Garglin $Zero^{TM}$ (Dong-A Pharmaceutical Co., Ltd.), Listerine Naturals $Citrus^{TM}$ (LC; IDS Manufacturing Ltd.), and Listerine Cool $Mint^{TM}$ (LM; IDS Manufacturing Ltd.). The composition, pH, and titratable acidity of the mouthwashes were investigated. Six bovine teeth specimens were prepared for each mouthwash group. Each of the six specimens was individually immersed in 30 ml aliquots of mouthwash for 1 minute, 30 minutes, 90 minutes, and 120 minutes, and the samples were placed in a $36.5^{\circ}C$ stirred incubator. The degree of mineral loss (${\Delta}F$) of the tooth surface area exposed to mouthwash, compared with normal teeth, was analyzed by quantitative light-induced fluorescence-digital. The difference in ${\Delta}F$ among mouthwash groups was examined by the Kruskal-Wallis H test (${\alpha}=0.05$). The contents of mouthwashes differed between Listerine and other products, and the pH ranged from 4.09 to 6.75. The titratable acidity of PS was the lowest at 0.63 ml and highest at 9.25 ml for LM. Minor mineral loss was observed when dental specimens were immersed in the Listerine products (LC and LM) for more than 90 minutes, but the degree of mineral loss for Listerine products was not statistically significantly different from that for groups without mineral loss. In conclusion, all five commercially available mouthwashes showed no harmful effects on tooth enamel.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.25 no.1
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• pp.6-11
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• 1989

Some distinctive defects in the conventional stow net were examined and presented in the previous report of this series. To find out the more effective gear by correcting the defects, the authors carried out another experiment by using a newly designed gear. 1. Special features of the newly designed gear are: (1) stretched width of front end on top, bottom and side panel are decreased 20%, on the other hand, the frank of the panels are increased 10% compared with the conventional gear. Front end of top and bottom panels are bias cutten up to 20% of the length of panels. (2) Length of the head rope and ground rope are shortened 6% by changing of the shape of the top and bottom panels. (3) Lacing lines are attached to four longitudinal seaming lines with suitable hanging ratio. (4) Stretched height of the shearing device were shortened 17%, and the buoyancy on top of the device were increased 20%. (5) Length of the biforked pendants were arranged to be shorter on top-most and bottom-most ones, and loner on middle ones. 2. The observed result can be expressed as (1) Wrinkles in the front end of top panels are removed and fringe line of panels become smooth. (2) Opening height of mouth is observed 3% higher than that of the conventional gear. (3) Opening width is 1.5 to 1.6 times wider than that of the conventional gear. (4) Hydrodynamic resistance is decreased 10%-17%.

• Journal of Convergence for Information Technology
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• v.12 no.4
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• pp.219-230
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• 2022

This study aims to evaluate the effect of sleep duration on obesity in Korean adult using data from the 8th Korea National Health And Nutrition Examination Survey in 2019. The study subjects were 5,213, and we performed frequency analysis, descriptive statistics, and multivariate regression analysis using the SPSS Win 27.0 program. The average sleep duration of the subjects was 6.8 hours per day, and the average body mass index (BMI) was 23.9 kg/m². As a result of bivariate analysis of factors affecting sleep duration, age, education level, stress, depression, diabetes, hypertension, and arthritis were significantly associated with sleep duration. The body mass index (BMI) of the group with less than 6 hours of sleep duration was 24.4, which was higher than that of other groups, and there was a significant negative correlation between sleep duration and BMI (B=-0.247; 95% CI=-0.334~ -0.160). In conclusion, in order to prevent obesity in adults, various efforts from the country and local communities are needed to increase sleep duration.

• Applied Biological Chemistry
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• v.17 no.3
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• pp.149-176
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• 1974

Eight substituted diphenyl ether herbicides and some of their photoproducts were studied in terms of solution phase photolysis under simulated environmental conditions by using a Rayonet photochemical reactor. The test compounds absorbed sufficient light energy at the wavelength of 300 nm to undergo various photoreactions. All the photoproducts were confirmed by means of tlc, glc, ir, ms, and/or nmr spectrometry. The results obtained are summarized as follows: Solution phase photolysis of C-6989: An exceedingly large amount of p-nitrophenol formed strongly indicates the readiness of the ether linkage cleavage of this compound as the main reaction in all solvents used. Photoreduction of nitro to amino group(s) and photooxidation of trifluoromethyl to carboxyl group were recognized as minor reactions. Aqueous photolysis of p-nitrophenol: Quinone(0.28%), hydroquinone (0.66%), and p-aminophenol (0.42%) were confirmed as photoproducts, in addition to a relatively small amount of an unknown compound. The mechanisms of formation of these products were proposed to be the nitro-nitrite rearrangement via $n{\rightarrow}{\pi}^*$ excitation and the photoreduction through hydrogen abstractions by radicals, respectively. Solution phase photolysis of Nitrofen: Photochemical reduction leading to the p-amino derivative was the main reaction in n-hexane. In aqueous solution, the photoreduction of nitro to amino group and hydroxylation predominated over the ether linkage cleavage. Nucleophilic displacement of the nitro group by hydroxide ion and replacement of chlorine substituents by hydroxyl group or, to a lesser extent, hydrogen were also observed as minor reactoins. Solution phase photolysis of MO-338: Photoreduction of the nitro to amino group was marked in the n-hexane solution photolysis. In the aqueous solution, photoreduction of the nitro substituent and hydroxylation were the main reactions with replacement of chlorine substituents by the hydroxyl group and hydrogen, and cleavage of the ether linkage as minor reactions. Photolyses of MC-4379, MC-3761, MC-5127, MC-6063, and MC-7181 in n-hexane and cyclohexane: Photoreduction of the nitro group leading to the corresponding amino derivative and replacement of one of the halogen substituents by hydrogen from the solvent used were the key reactions in each compound. Aqueous photolysis of MC-4379: Cleavage of the ether linkage, replacement of the carboxymethyl by hydroxyl group, hydroxylation, and replacement of the nitro by hydroxy group were prominent with photoreduction and dechlorination as minor reactions. Aqueous photolysis of MC-3761: Cleavage of the ether linkage, replacement of the carboxymethyl by hydroxyl group, and photoreduction followed by hydroxylation were the main reactions. Aqueous photolysis of MC-5127: Replacement of carboxyethyl by hydrogen was predominant with ether linkage cleavage, photoreduction, and dechlorination as minor reactions. It was obvious that the decarboxyethylation proceeded more readily than decarboxymethylation occurring in the other compounds. Aqueous photolysis of MC-6063: Cleavage of the ether linkage and photodechlorination were the main reactions. Aqueous photolysis of MC-7181: Replacement of the carboxymethyl group by hydrogen and monodechlorination were the remarkable reactions. Cleavage of the ether linkage and hydroxylation were thought to be the minor reactions. Aqueous photolysis of 3-carboxymethyl-4-nitrophenol: The photo-induced Fries rearrangement common to aromatic esters did not appear to occur in the carboxymethyl group of this type of compound. Conversion of nitro to nitroso group was the main reaction.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.5
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• pp.877-884
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• 2002

This study was carried out to examine nutrients intake and food preference in 100 elderly people aged over 85 years residing in Namhae-gun Kyungnam. Mean daily energy intake and Korean recommended dietary allowances (RDA) percent were 1547.6$\pm$452.7 kcal and 91.5%, respectively. Mean daily intakes of protein (63.1$\pm$28.2 g), iron (16.7$\pm$11.2 mg), vitamin Bi (1.0410.4 mg) and vitamin C (97.0$\pm$45.3 mg) were higher than RDA. The intakes of calcium (418.1$\pm$189.7 mg) and vitamin B2 (0.94$\pm$0.5 mg) were shown to be 58.4% and 78.4% of the RDA. Females had higher intakes of energy and most other nutrients than males. Major food source of energy and protein intakes was rice and cereals, and that of lipid intake was meat, fish, egg and beans. Cooked rice, all kind of vegetables, fish, yogurt and sugars were preferred to the subjects. The most preferred taste was sweet.