• The korean journal of orthodontics
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• v.24 no.1 s.44
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• pp.221-231
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• 1994

The short-term effects of plaque control instruction were studied in 42 adolescent orthodontic patients under active fixed treatment. At first visit, all the patients were received plaque control instruction using materials such as oral hygiene education slides, dentiform, disclosing agents, tooth brush and interdental brush. After that, Pateints were asked to perform the tooth brushing according to instructions. Such a procedure was repeated every week lot 3 weeks. Plaque index and bleeding index were scored once a week for 4 weeks and were compared according to ages, sex and duration with fixed appliance. The results were as follows: 1. Plaque control instruction was effective in reducing plaque accumulation and gingival inflammation of the orthodontic patients. 2. The effect of plaque control instruction was continued during 3 weeks among all groups of subjects, and it was prominent at the first week. 3. There was no statistically significant difference in the effects of the plaque control of instruction according to sex, ages, or duration with fixed appliances.

• The Journal of the Korean dental association
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• v.50 no.9
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• pp.558-565
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• 2012

Dental caries is multifactorial local disease which involves destruction of the hard tissues of the teeth by metabolities produces by microorganisms. Recently, there has been growing interest in the role of nitric oxide (NO) and glutathione (GSH) in caries incidence. The aim of the study was to survey the studies reported the association among salivary NO, GSH and dental careis. Three studies reported the association between NO and dental caries. However, the results were contradictory. Only one study showed negative association between GSH and dental caries. In Korea, NO showed negative association with Lactobacilli and GSH showed positive association with dental caries. These observations suggest the possibility that NO and GSH could be new biomarkers for dental caries. However, further study should be needed.

• Korean Journal of Materials Research
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• v.6 no.5
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• pp.504-514
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• 1996

고상반응법과 sol-gel법으로 제조된 NASICON의 상온과 25$0^{\circ}C$에서의 X선 회절 데이터를 리트벨트 분석을 행하였다. monoclinic에서 rhombohedral로 상전이가 일어나도 원자들의 변위는 매우 작았다. 이들 상간의 ZrO6 팔면체와 Si(P)O4 사면체고 구성된 골격은 다소 다르게 나타남으로 인하여 Na 이온의 자리도 변하였다. 이들 방법으로 제조된 NASICON은 Zr이 부족한 비화학양론 화학식, Na 1+x+4yZr2-xSixP3-xO12으로 표현될 수 있었다. 제조법에 따라 Na 이온들의 자리 점유율이 변화하였다. 상온에서는 Na(1)과 Na(3)자리의 자리 점유율의 합이 거의 1에 가까웠으나, 25$0^{\circ}C$에서는 Na(1)과 mid Na 자리를 단위 화학식 당 한 개를 약간 상회하는 Na 이온이 점유하였다. 상온과 25$0^{\circ}C$에서의 Na 이온의 이동 경로가 다름을 알 수 있었다. 또한 25$0^{\circ}C$에서는 Na(1)자리와 Na(2)자리 사이에 mid Na가 존재하며, 이 자리가 Na 이온의 이동에 중요한 역할을 함을 알 수 있었다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1449-1450
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• 2011

The SiC-$ZrB_2$ composites were produced by subjecting a 40:60 (vol.%) mixture of zirconium diboride($ZrB_2$) powder and ${\beta}$-silicon carbide (SiC) matrix to spark plasma sintering(SPS) under argon atmosphere at 50MPa(P50) and 60MPa(P60) pressure. The relative density, 94.13% of P60 sample was lower than that, 94.75% of P50 sample. Reactions between ${\beta}$-SiC and $ZrB_2$ were not observed via x-ray diffraction (hereafter, XRD) analysis. The trend of flexural strength of SiC-$ZrB_2$ composites were in accordance with the relative density. The properties of a SiC-$ZrB_2$ composites through SPS under argon atmosphere were positive temperature coefficient resistance in the temperature range from $25^{\circ}C$ to $500^{\circ}C$, and electrical resistivity of P50 and P60 sample were $6.75{\times}10^{-4}$ and $7.22{\times}10^{-4}{\Omega}{\cdot}cm$ at room temperature, respectively.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.917-925
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• 2009

본 연구는 실제 사용자 언어로서의 사용성 평가를 시도하기 위해 진행되었다. 기존의 획일화 된 잣대로서의 평가가 아닌, 사용자가 원하는 사용성 요소가 충족되었을 때의 지각되는 사용성에 대한 만족도를 알아보고자 한 것이다. 이에 본 연구에서는 사용자의 유형에 따라 제품 및 서비스의 인터페이스에 중요하다고 생각하는 사용성 요소가 다를 것이라고 가정한 뒤, 그 사용성 요소의 충족여부에 따라서 사용자의 주관적인 만족도가 다르게 나타날 것이라고 예상하였다. 이 연구문제를 위하여 혁신 수용의 사용자 유형 별로 가장 중요하다고 생각하는 사용성 요소를 추출하였다. 조기사용자는 사용성 요소 중 Affect의 사용성 요소를 가장 중요하다고 평가하였으며 후기사용자는 사용성 요소 중 Productivity의 사용성 요소를 가장 중요하다고 평가하였다. 이후 각각의 사용자 유형에 중요평가된 사용성 요소가 충족되거나 충족되지 않은 프로토타입을 제시한 뒤, 사용 경험의 만족도를 조사한 결과, 각 사용자 유형 내에서의 만족도는 충족여부에 따라 통계적으로 유의미한 차이를 보였으나, 각 사용자 유형 간의 만족도는 충족여부에 따른 통계적으로 유의미한 차이를 나타내지 않았다. 본 연구의 결과는 사용성평가를 평가자의 언어가 아닌 사용자의 언어로 측정하는 새로운 평가방식 개발의 기초자료로 활용될 수 있다. 또한 본 연구는 사용자 유형 별 중요하게 기대하는 사용성 요소의 결과를 제시함으로써 제품 및 서비스의 인터페이스의 개발에 있어 사용자 군 별 중요하게 고려되어야 할 속성들의 판단자료를 제공할 수 있다는 점에서 의의를 갖는다.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.516-520
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• 2009

This study describes aerodynamic characteristics for the HAWT (Horizontal Axis Wind Turbine) rotor blade using general CFD(Computational Fluid Dynamics) code. The boundary conditions for analysis are validated with the experimental result by the NREL (National Renewable Energy Laboratory)/NASA Ames wind tunnel test for S809 airfoil. In the case of wind turbine rotor blade, complex phenomena are appeared such as flow separation and re-attachment. Those are handled by using a commercial flow analysis tool. The 2-equation k-$\omega$ SST turbulence model and transition model appear to be well suited for the prediction. The 3-dimensional phenomena in the HAWT rotor blade is simulated by a commercial 3-D aerodynamic analysis tool. Tip vortex geometry and Radial direction flows along the blade are checked by the analysis.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.4
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• pp.293-302
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• 1998

This study was performed to investigate the behavior of chlorobenzenes (CIBZS) and chlorophenols (CIPhs) in a thermally treated MSWI fly ash. The experiment was carried out in a fixed bed reactor at the temperature range of 300~$600^{\circ}C$. Reaction time range was between 30 and 120 minutes, and NB and 02 gases were used as carrier gas. The decomposition rate of CIBZS was more affected by reaction time than by the reaction temperature. The decomposition rate of CIPhs was affected by both parameters. Decomposition rate of CIBZS and CIPhs reached 80.4% and 96.6% at $600^{\circ}C$, 120 min, respectively. Considering the effect of O2 content, decomposition rate of CIBZS and CIPhs was the highest at 10% of O2 content. Declorination and decomposition reactions Pere investigated by analyzing homologue distribution. Higher chlorinated CIBZS and CIPhs homologue decreased but lower chlorinated compounds increased with the increase of temperature. Effect of O2 on the homologue distribution of these compounds was not clear in the range of our experiment conditions.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.10
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• pp.1817-1824
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• 2000

This study is carried out to investigate the discharge characteristics of PCDD/Fs from municipal solid waste(MSW) incinerator, According to the results measured at several air pollution control devices(APCDs), the largest amount of polychlorinated dibenzo-p-dioxins/dibenzofurans(PCDD/Fs) are found at selective catalytic reduction (SCR) inlet. Therefore, it concludes that the electrostatic precipitator(EP) provides the appropriate condition for the formation of PCDD/Fs. The concentration of PCDD/Fs shows a large difference with the season. The concentration of PCDD/Fs in winter is higher than that of autumn, which suggests that the formation of PCDD/Fs is affected by the MSW components and the operation condition of municipal solid waste incinerator(MSWI).

• Journal of the Mineralogical Society of Korea
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• v.9 no.1
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• pp.43-53
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• 1996

The detailed crystal chemistry of ilmenite from the Hadong massif was studied by the EPMA, M ssbauer spectroscopy, and Rietveld structural refinement using X-ray powder diffraction data. The ilmenite-bearing anorthosite shows complicated mineral assemblage which consists of plagioclase, clinopyroxene, hornblende, biotite, chlorite, apatite, allanite, and zircon. Anorthite is andesine in composition (Ab 28-57), and clinopyroxene drops in ferro-hypersthene (Fs 62-70). Ilmenite is trigonal symmetry with R space group, whose structure shows the alternation of Fe2+ (M1 site) octahedral layer and Ti (M2 site) layer along c axis. M ssbauer spectroscopy indicates that there are three doubles which assigned to couple of Fe2+($\delta$=0.812, 0.890mm/sec) and one Fe3+($\delta$=0.303mm/sec) in octahedral sites. Their Fe3+/$\Sigma$Fe is 0.065 and chemical formula is established as Fe2+0.94Fe3+0.07Ti0.97O3 using both EPMA and M ssbauer analysis. Rietveld structural refinement reveals that site occupancies of Fe in M1 and Ti in M2 are 91.2% and 89.4%, respectively. This implies that Ti and Fe2+ are alternatively occupy M1 and M2 sites. In addition, smaller M2 site is more preferable to Fe3+ occupancy over M1.

• Korean Journal of Health Education and Promotion
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• v.2 no.1
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• pp.107-112
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• 1984

In order to develop the school dental health care in rural area, the author collected data about the population of all 6-17 year students living in Young dong-gun county, and Surveyed their dental health cares during one year of 1982. From the collected data, several dental health indices such as percentage of students of all population, percentage of students who visited dentists once or more during one year, average annual dentist visit and average annual dental treatment case were calculated and discussed. The obtained results were as follows; 1. The percentage of students of all population in Young dong-gun county was 29.65%. 2. The percentage of students who visited dentists once or more during one year was 4.67%. 3. The average annual dentist visit per student was 0.11. 4. The average annual dental treatment case per student was 0.16. 5. The oral examination case was 0.05, intraoral radiograph 0.01, oral prophylaxis 0.00, filling of dental carious lesion 0.02, pulp treatment 0.02, extraction of teeth 0.04, and others 0.02 annually in the average. In comparison with detectable need for dental treatment cases, oral prophylaxis was not supplied at all, filling of dental carious lesion was supplied about 1% and extraction of teeth was supplied about 10% of detectable need. 6. It was recommended that school incremental dental care project should be developed for school dental health programme in order to supply all of the detectable need for dental treatment.