• Journal of Korean society of Dental Hygiene
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• 제13권6호
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• pp.1041-1046
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• 2013

Objectives : The purpose of the study is to investigate the significant(SiC) index of the 12 year old children's permanent teeth caries experience. A total of 428 children aged 12 years old were recruited from metropolitan city(215 children) and rural area(213 children) in this study. SiC index was obtained from DMFT index. Data were analyzed by gender, region, and DMFT. Methods : DMFT index and Sic index were analyzed and compared by pit and sealant fissure treatment, dental caries, gender, and areas. A total of 428 children aged 12 years old were recruited from metropolitan city(215 children) and rural area(213 children) in this study. Results : Boy students(6.73) tended to have a higher SiC index than girl students(7.84). There were significant differences(p<0.05). DMFT index in urban area was 2.59, and that in rural area was 3.35. In SiC index, rural children showed a higher index(7.77) than urban children(6.72).There existed a significance between DMFT index and SiC index(p<0.05). Conclusions : It is important to educate and to develop the oral disease prevention program for the high risk group children. This study showed the relationship between DMFT index and SiC index in 12 year old children in urban and rural areas.

• Journal of dental hygiene science
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• 제11권3호
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• pp.229-234
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• 2011

This study obtained DMFT index(9271 people) in population with more than 6 years old based on data of 2009 Korea National Health and Nutrition Examination Survey, and calculated SiC index(2,517 people) by classifying group with high risk, which is 1/3 in high rank out of it. The aim was to confirm existence of the group with high risk of dental caries, and was to emphasize necessity of preventive strategy for the group with high risk. Statistical analysis was carried out t-test by using STATA 11.0 program. 1. DMFT index accounted for 45.0%(4,174 people) for men and 55.0%(5,097 people) for women. SiC index stood at 2,517 people. Men accounted for 36.3%(914 people). Thus, women were larger with 64.7%(1,603 people). 2. Seeing the mean in DMFT index and SiC index, the more rise in age led to the bigger difference in the mean between two groups. Especially, the difference was shown more than 4 points on the average for 13 and 14 years old and more than double on the average from over 15 years. 3. As a result of comparing gender, DMFT index was higher in women than men from over 14 years old. SiC index wasn't significant. However, women were indicated to be 1 piece more than men at the age of 9 and 14. 4. As a result of comparing by region, both DMFT index and SiC index were indicated to be higher in the rural area for their over 60s. Seeing the above results, the group with high risk is showing the higher rate of experiencing dental caries than DMFT-index in the whole. Thus, the comprehensively & intensively preventive management seems to be likely needed on group with high risk.

• Journal of dental hygiene science
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• 제6권1호
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• pp.19-22
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• 2006

To prepare basic data for oral health promotion of high school students through the survey of the recognition of oral health, a questionnaire survey was conducted for 369 students. Statistical analysis was conducted using the SPSS 11.5 with $x^2$-test, fisher's exact test, t-test. The obtained results were as follows 1. The average of the high school student's DMF rate, DMFT index and SiC Index was 87.53%, 3.36, 6.50. 2. The average of the high school student's oral health knowledge was more than 3, 70% of highschool did right toothbrushing. But toothbrushing frequency of student of more than 60% was less than 2 a day. 3. In SiC Index, Only 30% of high school students received oral health education and 80% of them recognized oral health manpower's education needs.

• Journal of the Korean Crystal Growth and Crystal Technology
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• 제17권2호
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• pp.47-51
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• 2007

F-doped SiOC : H thin films with low refractive index were deposited on Si wafer and glass substrate by plasma enhanced chemical vapor deposition (PECVD) as a function of rf powers, substrate temperatures, gas rates and their composition flow ratios ($SiH_4,\;CF_4$ and $N_2O$). The refractive index of the F-doped SiOC : H film continuously decreased with increasing deposition temperature and rf power. As $N_2O$ gas flow rate decreased, the refractive index of the deposited films decreased down to 1.3778, reaching a minimum value at rf power of 180W and $100^{\circ}C$ without $N_2O$ gas. The fluorine content of F-doped SiOC : H film increased from 1.9 at% to 2.4 at% as the rf power was increased from 60 W to 180 W, which results in the decrease of refractive index.

• Journal of the Korean Vacuum Society
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• 제18권6호
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• pp.435-439
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• 2009

The reason of lowering the dielectric constant of SiOC film was studied using parameters obtained from C-V measurement and refractive index. SiOC film was formed by the force of ionic bonding during the recombination of dissociated gases. Generally, the dielectric constant was obtained from the square of the refractive index or C-V measurement using the metal/insulator/Si structure. The dielectric constant consists of the ionic and electronic elements. It was researched about the dielectric constant of SiOC film using the average of the ionic and electronic elements. The dielectric constant decreased after annealing process. As deposited films trended toward the dielectric constant consisted of most ionic elements, on the other hand, annealed films mostly consisted of electronic elements. Because the effect of ionic elements reduced after annealing. Consequently, it was found that the electronic effect of SiOC film increased and the ionic effect of SiOC film decreased by the after-annealing.

• Applied Microscopy
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• 제46권1호
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• pp.27-31
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• 2016

It has been investigated what kind of characteristic X-ray in electron probe micro-analyzer (EPMA) is effective for the determination of compounds of Si series materials. After comparing the characteristic X-rays among the primary and secondary lines in $K_{\alpha}$ and $K_{\beta}$ obtained from the Si series standard samples, it was found that the secondary line of $K_{\alpha}$ exhibited the most informative spectrum although the intensity was considerably weak. As a result of analyzing the spectrum shapes of the Si series standard samples, the spectrum shape of the secondary line of $K_{\alpha}$ for SiC was different from those for other Si compounds. To grasp the characteristics of the shape, a line was perpendicularly drawn from the peak top to base line in order to divide a spectrum into two areas. The area ratio of right to left was defined to call as the asymmetry index here. As a result, the asymmetry index value of the SiC was greater than one, while those of other Si compounds were less than one. It was found from the EPMA analysis that identification of SiC became successful to distinguish from other Si compounds and this method was applicable for micro-sized compounds in a practical composite material.

• Journal of the Korean institute of surface engineering
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• 제29권6호
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• pp.797-802
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• 1996

Hydrogenated amorphous silicon carbide (a-SiC:H) films have been deposited on unheated substrates by low frequency (50Hz) plasma using $SiH_4+CH_4+H_2$ gas mixtures. Deposition rate, refractive index, optical band gap, Vickers hardness and IR spectrum of the deposited a -SiC:H films have been measured for various rations of gas flow rates k(=$CH_4/SiH_4$, 0.5k4) with a constant $H_2$ flow rate (100sccm). As k increases, the deposition rate of the a-SiC:H films increases up to the maximum value of about 220nm/h at k=2.5, and then it decreases. The refractive index of the films was 2.6 for k=2.5, while the optical band gap of the films was 3.3eV for k=2.2. The maximum value of Vickers hardness of the films was 1500Hv at k=1. The infrared transmission measurement shows that the films contain both Si-C and Si-$CH_3$ bonds.

• Journal of the Korean Vacuum Society
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• 제19권3호
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• pp.230-235
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• 2010

In this paper, we controlled the deposition rate and reflective index with process conditions that are TCP power, gas flow ratio and bias for optical properties of $SiO_2$ thin film using TCP-CVD equipment. We obtained a excellent $SiO_2$ thin film which has a excellent uniformity (<1 [%]), deposition rate (0.28 [${\mu}m$/ min]) and reflective index (1.4610-1.4621) within 4" wafer with process conditions ($SiH_4:O_2$=50 : 100 [sccm], TCP power 1 [kW], bias 200 [W]) at [$300^{\circ}C$].

• Journal of the Semiconductor & Display Technology
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• 제13권3호
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• pp.27-33
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• 2014

To develop high efficiency crystalline solar cells, the $SiN_x$ film for surface passivation and anti-reflection coating is very important and it is generally deposited by PECVD. In this paper, the $SiN_x$ film deposited by Hot-Wire chemical vapor deposition(HWCVD) that has no plasma damage was studied. First, to optimize the $SiN_x$ film deposition process, $SiH_4$ gas rate and substrate temperature were varied and then refractive index and thickness were measured. When $SiH_4$ gas rate was 22sccm and substrate temperature was $100^{\circ}C$, refractive index was 1.94 and higher than that of other process conditions. Second, the lifetime was measured by varying the annealing temperature and time. The annealing process was made from 5 to 30 minutes at $300{\sim}500^{\circ}C$. When the annealing temperature was $100^{\circ}C$ and time was 10minute, the lifetime was the highest. The lifetime of annealed samples was also measured after the firing process at $975^{\circ}C$. Although the lifetime of all samples was decreased by firing process, the lifetime of annealed samples before the firing process was higher than that of fired samples only. Finally, the characteristics of solar cells with HWCVD $SiN_x$ film were measured.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.247-250
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• 2001

We studied optical properties of SiON thin-film in the applications of optical waveguide. SiON thin-film was grown in $300^{\circ}C$ by PECVD(plasma enhanced chemical vapor deposition) system. The change of SiON thin-film composition and refractive Index was studied as a function of varying $NH_3$ gas flow rate. As $NH_3$ gas flow rate was increased, Quantity of N and refractive index were increased at the same time. By the results, we could form the SiON thin-film to use of a waveguide with refractive index of 1.6. We analyzed the conditions of the thin-film with FTIR(fourier transform infrared) and OES (optical emission spectroscopy). N-H bonding($3390cm^{-1}$ ) can be removed by thermal annealing. And we could observe the SiH bonding state and quantity by OES analysis in $SiH_4$