• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.05a
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• pp.79-84
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• 1993

This paper describes the development of lithium rechargeable cell. $LiCoO_2$ is recently recognized as a suitable cathode active material of a high voltage, high energy lithium rechargeable batteries because $Li^+$ ion can be electrochemically deintercalated/intercalated from/to $Li_xCoO_2$. The transition metal oxide of $LiCoO_2$ was investigated for using as a cathode active material of 4V class Li rechargeable cell. $LiCoO_2$ cathode was prepared by using a active material of 85 wt%, graphite powder of 12 wt% as a conductor and poly-vinylidene fluoride of 3 wt% as a binder. The electrochemical and charge/discharge properties of $LiCoO_2$ were investigated by cyclic voltammetry and galvanostatic charge/discharge. The open circuit voltage of prepared $LiCoO_2$ electrode exhibited approximately. potential range between 3.32V and 3.42V. During the galvanostatic charge/discharge, $LiCoO_2/Li$ cell showed stable cycling behavior at scan rate of 1mV/sec and potential range between 3.6V and 4.2V. Also its coulombic efficiency as function of cycling was 81%~102%. In this study the $LiCoO_2/Li$ cell showed the available discharge capacity of 90.1 mAh/g at current density of $1mA/cm^2$ and cell discharge voltage range between 3.6V~4.2V.

• 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 Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2478-2484
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• 2009

The purpose of this study is to conduct an oral examination of total 220 students (1st grade) at S Boys' High School in Seoul metropolitan City. The results of oral examination can be outlined as follows: According to survey on experience of oral symptoms 85.5% students had no experience of tooth fracture, 76.8% students had no experience of hemodia, and 90.9% students had no experience of toothache. And it was found that 86.4% students had no experience of periodontal disease, 98.2% students had no experience of intraoral pain, and 88.2% had no experience of subjective halitosis symptom. According to survey on oral health behaviors, 73.6 % students had no experience of visiting any dental clinic over last one year. In particular, it was found that 57.3% students brushed their teeth after breakfast every day, 19.1% students didn't enjoy having any confectionery or sweet stuff, or taking soft drink like coke on a daily basis, and 19.5% students used fluoride toothpaste for toothbrushing as of this survey. According to oral health examination, 55.9% students had no dental caries, and 44.1% students had dental caries. And it was found that most students (79.2%) had dental calculus resulting from periodontal disease.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.4
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• pp.409-414
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• 2008

Porous carbon electrode for electrosorption was prepared by a wet phase inversion method. Carbon slurry that was a mixture of activated carbon powder(ACP) and PVdF solution was cast directly upon a graphite sheet by means of a casting knife. Porous carbon electrodes were fabricated by immersing the cast film in pure water as a non solvent. Physical and electrochemical properties of carbon electrodes prepared with various ACP contents(50.0, 75.0, 83.3, 87.5, 90.0 wt %). From the SEM images we can verify that the electrode was porous. The average pore sizes determined for the electrodes fabricated with various ACP contents ranged from 72.7 to 86.4 nm and the size decreased as the ACP content increased. The electrochemical properties were characterized by cyclic voltammetry(CV) method. All of the voltammograms showed typical behavior of an electric double layer charging/discharging on the carbon surface. The capacitance increased with the ACP content and the values ranged from 2.18 F/cm$^2$ for 50 wt% ACP to 4.77 F/cm$^2$ for 90 wt% ACP.

• Journal of Korean society of Dental Hygiene
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• v.7 no.1
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• pp.91-103
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• 2007

The purpose of this study was to pave the way for the development of oral health promotion programs for children from the low-income class. The subjects in this study were 322 children from the city of Incheon. Some of them visited local childcare centers, and the others attended six different adjacent elementary schools. Their awareness of oral health, oral health behavior and preventive-treatment experience were investigated in May 2005, and whether there were any characteristics in their visit of dental institutions was checked. Besides, whether their parents advised them to brush their teeth before turning in was examined. The findings of the study were as follows: 1. 22.0 percent of the children investigated were visiting local childcare centers, and 78.0 percent weren't. The guardians of the former group largely received high-school(50.7%) and middle-school or lower education(22.5%), and those of the latter group mostly received high-school(41.0%) and college- or higher education(35.5%)(pE0.001). The common monthly mean house-hold income of the former was one million won or less(54.9%) or ranged from 1.01 to 2.00 million won(19.7%), and the most prevalent monthly mean household income of the latter was between 2.01 and 3.50 million won(28.7%). The second most dominant monthly mean household income of the latter ranged from 1.01 to 2.00 million won(28.3%), and the third most common one was 3.50 million won or more(12.0%)(pE0.001). 2. The most prevalent daily toothbrushing frequency among the local childcare center visitors was twice(39.4%), followed by three times(19.7%). The third largest group of the visitors brushed their teeth after each meal(19.7%). The most dominant daily toothbrushing frequency among the non-users of local child care centers was twice(54.2%), followed by three times(29.1%)(pE0.01). As to the way of toothbrushing, 58.2 percent of the visitors and 74.9 percent of the non-visitors brushed their teeth by turning their toothbrush or up and down(pF0.05). 62.0 percent of the former and 74.9 percent of the latter always brushed their teeth before turning in, and whether they visited local childcare centers made a significant difference to that(pE0.05). 3. 69.7 percent of the non-visitors were always advised by their parents to do toothbrushing before turning in, and the visitors who were given the same advice all the time numbered 29.6 percent(pE0.001). 4. 56.4 percent of the visitors and 72.1 percent of the non-visitors had ever visited dental institutions over the past year. Dental hospitals and clinics were identified as the dental institutions that they visited the most, and they mostly received dental-caries treatment or had a tooth out there. 49.3 percent of the visitors and 35.1 percent of the non-visitors had ever had a toothache. 5. Sealant was experienced by 42.3 percent of the visitors and 46.2 percent of the non-visitors to prevent dental caries(pF0.05). 33.8 percent of the visitors underwent fluoride application, and that rate was higher than that of the non-visitors with the same experience that stood at 22.7 percent(pE0.05). The visitors mainly acquired knowledge on oral health through other channels that weren't specified in the questionnaire(28.2%), and the non-visitors did it mostly at dental clinics(39.0%)(pE0.001).

• Journal of dental hygiene science
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• v.10 no.5
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• pp.379-385
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• 2010

The purpose of this study was to examine the oral health knowledge and oral health practice of teachers in early childhood education institutions. The subjects in this study were 169 teachers who worked in early childhood education institutions. After a survey was conducted, the collected data were analyzed with a SPSSWIN 14.0 program. The findings of the study were as follows: 1. Concerning oral health knowledge, they got a mean of 7.97(9), 2.66(3), 2.86(5), 2.42(5) and 1.04(2) respectively in knowledge on dental caries, toothbrushing, periodontitis, fluoride and diet. Overall, they got a mean of 16.98 in 24 items, and the score corresponded to approximately 70 out of 100 points. 2. As for oral health practice, tongue cleaning(4.22) was what they did the most to take care of their oral health, and they just got 2.60 in regular dental checkup. Overall, they got about 3.11 in oral health practice. 3. Regarding relationship between general characteristics and oral health knowledge, the teachers who were in their 30s got 17.47 in overall oral health knowledge, and those with a career of five to less than 10 years got 17.50. The teachers who received college or higher education got 17.27, and the principals got 18.26. Those who had ever received education on oral health got 17.01. But the gaps between them and the others were not statistically significant. 4. As to connections between general characteristics including age and oral health practice, restricted sugar intake, regular dental checkup, the use of oral hygiene supplies, tongue cleaning and overall oral health practice were more prevailing among the older teachers, and the gaps between them and the younger teachers were statistically significant. 5. In terms of relationship between oral health knowledge and oral health practice, there was no statistically significant relationship between the two on the whole, but better oral health knowledge led to better oral health practice in each part. This study shows that various oral health education programs for the kindergarten teachers should be developed and continuous education through the programs is important to improve the knowledge of oral health and to change oral health behavior.