• 구강회복응용과학지
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• 제23권3호
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• pp.259-268
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• 2007

purpose: This study was to evaluate the shear bond strength of Lithium Disilicate Glass-Ceramic by removable method of temporary cement on the abutment tooth. Material and Method: Sixty molar teeth of human with the occlusal surface up were mounted in acrylic resin blocks. The 45 specimens were prepared to exposure dentin by diamond bur and the eugenol-containing temporary cement($Cavitec^{TM}$ ($KERR^{(R)}$, U.S.A)was applied to the dentin surfaces. After initial removal of the cement with a dental explorer, the specimens were divided into 4 groups of 15 specimens each. The dentin surfaces of the specimens were treated by rotary instrument with as follow pastes: $Zircate^{(R)}$ prophy paste(Dentsply, U.S.A), Radent Prophy Paste(Pascal company,inc. U.S.A), and Dental pumice(Wip mix corporation,U.S.A). An adhesive resin luting agent(Variolink $II^{(R)}$, Ivoclar Vivadent, Leichtenstein) including Monobond-S and $Excite^{(R)}$ was applied to all specimens. The ceramic specimens were made with an A1 ingot of IPS Empress $II^{(R)}$ (Ivoclar Vivadent, Leichtenstein). After the specimens were stored in distilled water for 48hr, the shear bond strength(MPa) was measured by a Universal testing machine(Zwick 145641, Zwick, Germany) at a 1mm/min cross-head speed. The data were statistically analyzed by one-way ANOVA and Duncan's multiple range test. Results: In all group, there were no significant differences in comparison with the control group(p>0.05). The pattern of most failure showed the mixed type of cohesive and adhesive failure. Conclusion: Resin bond strength of IPS Empress $II^{(R)}$ was not affected by removal method of the temporary cement.

• Journal of Astronomy and Space Sciences
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• 제32권3호
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• pp.181-187
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• 2015

Storm sudden commencements (SSCs) occur due to a rapid compression of the Earth's magnetic field. This is generally believed to be caused by interplanetary (IP) shocks, but with exceptions. In this paper we explore possible causes of SSCs other than IP shocks through a statistical study of geomagnetic storms using SYM-H data provided by the World Data Center for Geomagnetism - Kyoto and by applying a superposed epoch analysis to simultaneous solar wind parameters obtained with the Advanced Composition Explorer (ACE) satellite. We select a total of 274 geomagnetic storms with minimum SYM-H of less than -30nT during 1998-2008 and regard them as SSCs if SYM-H increases by more than 10 nT over 10 minutes. Under this criterion, we found 103 geomagnetic storms with both SSC and IP shocks and 28 storms with SSC not associated with IP shocks. Storms in the former group share the property that the strength of the interplanetary magnetic field (IMF), proton density and proton velocity increase together with SYM-H, implying the action of IP shocks. During the storms in the latter group, only the proton density rises with SYM-H. We find that the density increase is associated with either high speed streams (HSSs) or interplanetary coronal mass ejections (ICMEs), and suggest that HSSs and ICMEs may be alternative contributors to SSCs.

• 우주기술과 응용
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• 제1권3호
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• pp.283-301
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• 2021

미국 NASA(National Aeronautics and Space Administration)와 유럽의 ESA(European Space Agency)에서는 미지의 세계를 탐구하려는 인류의 지적 호기심을 충족하는 목적과 더불어, 우주를 안전하고 지속가능한 환경으로 개척하려는 원대한 꿈을 모토로 하여 다양한 연구개발에 착수하고 있다. 2020-30 년대에는 10 미터급 우주망원경이 개발되는 등 첨단 거대관측장비가 가동될 것으로 예상하며, 한국에서도 0.15 m 급 NISS(near-infrared imaging spectrometer for star formation history) 개발에 이어 0.2 m급 SPHEREx(spectro-photometer for the history of the universe, epoch of reionization, and ices explorer) 등 소형탐사망원경에 국제협력 파트너로 참여하고 있다. 그러나, 아직 우주망원경의 개발과 운영에 있어 국내 경험은 부족하고, 한국에서 주도하여 망원경을 개발하기 위한 장기적인 계획이 부재한 상황이다. 우리 손으로 만든 장비를 사용하여 인류가 경험하지 못한 미지의 세계에 대한 질문에 답하려면, 산학연관 관계자 간 긴밀한 협력을 통해 우주망원경 건설의 기획과 준비가 절실히 필요하다. 본 연구에서는 한국형우주망원경 개발의 필요성, 배경과 개발목표 및 기대효과를 개념적으로 정리하며, 장기적 안목에서 기획을 준비하는 워킹그룹을 제안한다. 이를 통하여 한국형 우주망원경 개발계획을 우리나라가 주도하여 수립하고, 우주개발 기술연구 분야에서 국가의 방향성을 수립하기 위한 소중한 발걸음을 시작하며, 한국형 우주망원경 워킹그룹이 우리나라의 우주천문학의 이정표를 세우는 기점이 되기를 기대한다.

• 대한소아치과학회지
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• 제24권1호
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• pp.27-40
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• 1997

This study investigated the effects of laser irradiation on the exposed pulp and the possibility of direct pulp capping with the $CO_2$ laser. Results were obtained from the observation of the residual pulpal healing process. Class V cavities on 48 anterior teeth from 8 adult dogs were prepared and pulp chambers were intentionally opened with dental explorer. The control group consisted of 16 teeth. $Dycal^{(R)}$(Caulk Co., U.S.A.) was applied to exposed site once bleeding was stopped. Cavities were sealed with $I.R.M^{(R)}$. In the experimental group 1 (16 teeth), laser(LASERSAT $CO_2^{(R)}$, Satelec Co.) was irradiated on the exposed pulp. The laser procedure followed the manufacturers recommendations for the treatment of human pulp(1.5 Watts, 0.2 seconds, unfocused), and cavities were sealed with $I.R.M^{(R)}$. In the experimental group 2 (16 teeth), laser was irradiated on the exposed pulp in a more powerful dosage(5.0 Watts, 0.2 seconds, unfocused), and cavities were sealed with $I.R.M^{(R)}$. Two dogs were sacrificed immediately after experiment and the others were sacrificed at intervals of one, three, and eight weeks respectively. All teeth were routinely processed and the pulpal tissues and odontoblastic layers were observed by the light microscope. The results were as follows; 1. In the control group, the initial mild inflammation had improved to normal by week eight. An active formation of reparative dentin was observed at week three, and at week eight, a firm dentin bridge was present beneath the $Dycal^{(R)}$ with no inflammatory responses in the remaining pulp. 2. In the experimental group 1, immediately following irradiation, the superficial shape of the exposed pulp was crater-like. And it was lined with the coagulated layer, $60{\sim}70{\mu}m$ in width. Moderate inflammatory pulpal conditions existing at week one were improved to mild at week eight. And from the week three specimens, a reparative dentin formation was observed in the adjacent odontoblastic layer of the exposed site. A dentin bridge at the exposed site, however, did not form during the experimental period. 3. In the experimental group 2, the width of the coagulation layer lining the crater was $70{\sim}130{\mu}m$. Beneath the coagulated layer, severe inflammatory pulpal responses were observed at week one, and conditions did not improve during the experimental period.

• 한국치위생학회지
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• 제8권4호
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• pp.229-240
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• 2008

Objectives : This study was to investigate the impact of dietary habits and obesity on level of oral health in the elementary school children and to characterize the relationship among dietary habits, obesity and level of oral health by DMFT index and perceived oral health. Methods : Participants were 314 total students from one elementary school who lived Yeosan. Self-administered questionnaires were given to the subjects from March 25 through May 12, 2008, to identify their the degree of dietary habits, perceived oral health. A trained investigator made an oral examination of them in natural light using a mirror and explorer to determine their DMFT index. We classified the subjects into Data were analyzed with T-test, one-way ANOVA, and Duncan's multiple range test, pearson correlation coefficient and multiple regression using the SPSS WIN 12.0 program. Results : Regarding dietary habit, the subjects achieved a mean of 10.52${\pm}$3.80 out of a maximum 20 points. The DMFT index in the subject was 0.60${\pm}$2.03. The group of obesity by gender were 19.2% and 22.5%. Moreover, those who were children and had more severe level of obesity felt that their perceived oral health and DMFT index were higher. There was a significant assocciation of oral health among elementary school children with obesity. Conclusion : These results suggest that oral health behavioral and attitude, dietary habits and obesity influenced the level of oral health. Thus further research targeting to positive attitude toward effective management of childhood obesity combined with significant dietary habits, may lead to promotion of oral health.

• 한국치위생학회지
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• 제14권4호
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• pp.479-484
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• 2014

Objectives : The aim of the study is to investigate the oral health knowledge, attitude and dental caries experience in Korean 12-year-old adolescents. Methods : The subjects were 2,196 adolescents living in Seosan, with an average age of 12.2 years. Data were collected using a self-administered questionnaire from April 10 through June 10, 2011. A trained investigator made an oral examination of them in natural light, using a mirror and an explorer to determine their DMFT index. Results : The prevalence rate of dental caries of adolescents was 59.1%. The DMFT index of the subjects was 1.98, which was lower than the national mean of 2.2 for the same age. The DMFT index was significantly higher in the female(2.25) than the male group(1.72). The attitude of oral health was positively related to DMFT index in this study(OR=1.25; CI=1.01-1.54). It appears that knowledge and attitude concerning oral health, among young Korean 12-year-old adolescents living in Seosan, are in need of improvement. Conclusions : Based on the findings, dental caries experience is associated with attitude of oral health. This result suggests that the implementation of oral health promotion should be considered for various factors related to attitude of oral health in adolescents.

• 대한소아치과학회지
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• 제25권3호
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• pp.576-582
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• 1998

The purpose of the study was to determine the ability of the caries activity test, 'Cariostat' to identify preschool children with dental caries. The subjects of this study were 76 children of 3 to 5 years of age. Oral examination was carried out to assess the caries experience using a mirror and explorer. In all subjects buccal plaque samples were obtained, incubated, and scored as the manufacturer's instructions for the Cariostat test. Statistical analyses were used with the Crosstabulation. The test group exhibited mean dft index 5.21, while 27.63% of subjects were caries free and had no restorations. The sensitivity of the Cariostat test was found to be 98.8% while the specificity was found to be 19.05% The results showed that caries activity measured by visual reading was highly significant to the Cariostat score and dft index(P<0.001). The Cariostat method has indicated the future possible occurrence of caries. The use of this method is meant to require in the caries prevention program.

• Journal of Oral Medicine and Pain
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• 제30권4호
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• pp.465-473
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• 2005

냉온자극 또는 잇솔질에 불편감을 호소하는 치과 외래 환자를 72명을 대상으로 레이저 조사를 시행한 실험군(45명)과 모의 레이저 조사를 시행한 대조군(27명)으로 나누어 지각 과민 치아의 치경부에 냉자극 및 기계적 자극을 가하여 대상자가 느끼는 불편감을 NPS로 평가하였다. 치아의 통증역치 평가를 위하여 전기치수검사기(EPT)를 사용하였다. 각 치아에 대한 레이저 조사에는 pulsed Nd:YAG 레이저를 사용하였고 조사조건은 1.5W, 20Hz, 75mJ/pulse으로 4분간 비접촉식으로 시행하였다. 대상자의 반응을 레이저 조사 전과 직후, 1주 이내, 2주 이내 각각 평가하여 다음과 같은 결과를 얻었다. 1. 지각 과민 치아에 대한 Nd:YAG 레이저 조사는 지각 과민을 완화시켜 주었으며 대조군에 비해 그 효과가 현저하였다. 2. 심한 지각 과민을 호소하는 치아에 대한 위약 효과는 존재하였으나 중등도의 지각 과민을 호소하는 치아에 대한 위약효과는 배제할 수 있었다. 3. 지각 과민 치아에 대한 Nd:YAG 레이저 조사는 전기치수검사에 의한 통증역치에 영향을 주지 않았다. 4. 지각 과민 치아에 대한 Nd:YAG 레이저 조사의 효과는 최소 2주는 지속되었다. 따라서 지각 과민 치아에 대한 치료법의 하나로 Nd:YAG 레이저 조사가 임상적으로 유용할 것으로 사료된다.

• 항공우주산업기술동향
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• 제6권1호
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• pp.56-64
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• 2008

위성체 총조립 및 시험(AIT; Assembly, Integration & Test)을 위한 전기지상지원장비(EGSE ; Electrical Ground Support Equipment)와 위성 임무 준비 및 운용을 위한 관제시스템(MCS; Mission Control System)은 동일한 시스템은 아니지만 많은 공통점과 호환 가능성을 갖고 있다. 하지만 우주 사업의 핵심 지상시스템인EGSE와 MCS는 사용 시기와 개발 조직이 달라서 오랫동안 별도로 개발 및 발전되어 왔다. 그러나 두 시스템이 기술적인 측면에서 유사한 기능과 역할을 하기 때문에 통합 또는 공통 개발에 대한 요구가 끊임없이 제기되고 있으며, 이미 세계적으로ECSS E70과 같은 관련 표준화 작업과 이를 바탕으로 실제 구현된 핵심 지상운영시스템의 개발이 최근에 기술적인 성숙을 이루고 있어 현재 거의 모든 우주 사업에서 핵심 지상운영시스템을 활용하거나 더 나아가 상용 제품을 적용하여 공통지상시스템을 개발하고 있다. EGSE와 MCS의 공통 기능에 관련된 표준화 작업은 ECSS를 통해 국제 표준(ISO, CCSDS 등)을 바탕으로 한 위성의 지상시스템에 대한 유럽 표준화 작업이 ECSS-E-70 Working Group에서 진행되고 있다. 여기서는 우주 산업에 관련된 표준화 단체인 ECSS에 대한 역사, 정책, 조직 및 문서 구조를 포함하여 ECSS에서 현재 진행되고 있는 지상시스템 및 운용 분야 관련 ECSS E70 표준화 작업의 내용 및 현황에 대해서 살펴보고자 한다.

• 대한화학회지
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• 제65권4호
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• pp.268-278
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• 2021

이 연구의 목적은 화학교사들의 반응적 교수 유형의 변화를 관찰하기 위하여 선행연구에서 제안한 반응적 교수 유형을 세분화하고, 반응적 교수 유형의 변화에 장애를 주는 요인을 알아보는 것이다. 이를 위하여 교육대학원 과정으로 개설한 화학교육 강좌에 참여한 화학교사들을 대상으로 반응적 교수법에 대한 소개, 반응적 교수법 사례 분석, 촉진자 유형의 교육시나리오에 대한 개별 과제 및 조별 토론 등이 포함된 교육프로그램을 제공하였다. 선행연구를 바탕으로 교사의 교수법은 변별자 유형, 전달자 유형, 안내자 유형, 촉진자 유형으로 분석하였을 때, 분류가 안되는 유형이 관찰되었으므로, 이 연구에서는 탐색자 유형과 해석자 유형 등 2가지 유형을 추가하여 화학교사들의 반응적 교수 유형을 세분화하였다. 또한 개별 과제 및 조별 토론 자료를 통해 교사들의 반응적 교수법 변화에 장애를 주는 요인을 관찰할 수 있었다. 연구에서 찾아낸 장애 요인으로는 교사 요인, 학생 요인, 환경 요인 등이 있었다. 장애 요인 중 교사 요인으로는 교사 주도 수업에 대한 신념, 지식 전달자로서 교사의 역할에 대한 신념, 교육과정에 따라야 한다는 신념, 학생에 대한 교사의 이해 부족, 학생 주도 확장을 이끄는 교사의 역량 부족 등이 나타났다. 학생 요인으로는 학생의 역량에 대한 불신이 있었다. 또한 환경 요인으로는 다인수 학급과 같은 교육 환경이 있었다. 이러한 장애 요인을 제거하기 위한 노력이 함께 이루어질 때 반응적 교수법에 대한 효과적인 교사교육이 이루어질 수 있을 것이다.