• 대한수학교육학회지:수학교육학연구
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• 제15권1호
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• pp.75-105
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• 2005

본 연구는 엑셀을 활용한 소그룹 모델링의 흐름과 학생과 엑셀의 상호작용이 모델링에 미치는 영향에 대한 이해를 바탕으로 추후 엑셀을 활용한 소그룹 모델링을 통한 수학 교수ㆍ 학습을 위한 기초적인 정보를 제공하는데 목적이 있다. 엑셀을 활용한 소그룹 모델링의 흐름을 알아보기 위해 학생들이 고려하는 양, 양들간 관계, 구성하는 모델을 바탕으로 모델링 주기를 살펴보았다 또한 학생과 엑셀의 상호작용이 모델링에 미치는 영향을 이해하기 위해 학생과 엑셀의 상호작용을 모델 형성, 모델 정교화, 모델을 통한 상황 해석ㆍ예측ㆍ통제 측면에서 분석하였다. 본 연구로부터 엑셀을 활용한 소그룹 모델링이 어떻게 이루어지는가와 학생-엑셀 상호작용 패턴에 대한 이해를 바탕으로 모델링 도구로서의 엑셀의 잠재력을 확인하고 학생들의 모델링 활동에 있어서의 강점과 취약점을 확인할 수 있었다. 또한 엑셀을 활용한 소그룹 모델링이 보다 효과적으로 이루어지기 위해 요구되는 교사 역할에 관한 시사점을 얻을 수 있었다.

• 한국과학교육학회지
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• 제33권7호
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• pp.1450-1470
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• 2013

본 연구는 다수준 포함 교수법(multi-level instruction)을 적용한 초등과학 프로그램을 개발하고, 이를 적용한 수업 과정에서 나타나는 학생들 간의 언어적 상호작용을 분석한 것이다. 이러한 연구 목적을 달성하기 위하여 경기도 H시의 B초등학교 5학년 27명을 대상으로 이질적인 4명의 학생으로 소집단을 구성하였고, 매 차시마다 2개 소집단의 수업 과정을 녹화하였다. 5학년 2학기 '1. 우리의 몸' 단원을 대상으로 다수준 포함 교수법을 적용한 초등과학 프로그램을 개발하였다. 언어적 상호작용은 크게 인지적 영역과 정의적 영역 두 가지 측면으로 분석하였다. 인지적 영역은 응답, 질문, 의견제시, 의견받기로 정의적 영역은 행동참여, 분위기 조절로 세분화하여 분석하였다. 다수준 포함 교수법을 적용한 초등과학 프로그램에서 학생들의 언어적 상호작용 분석 결과는 다음과 같다. 첫째, 인지적 영역과 관련된 언어적 상호작용이 정의적 영역과 관련된 상호작용에 비해 많이 일어났다. 둘째, 인지적 영역에서는 중위수준 아동의 언어적 상호작용 빈도가 가장 높았고, 정의적 영역에서는 상위수준 아동의 빈도가 가장 높았다. 인지적, 정의적 영역에서 모두 하위수준 아동의 빈도가 가장 낮게 나타났다. 셋째, 인지적, 정의적 영역에서 상위-중위수준 아동 사이에는 언어적 상호작용의 빈도에 차이가 없었다. 그리고 상위-하위수준 아동보다 중위-하위수준 아동에게서 유의하게 차이가 있는 상호작용 유형이 더 많았다. 중위-하위수준 아동은 행동 참여를 제외한 모든 영역에서 유의한 차이가 있었다. 넷째, 시간이 지날수록 전반적으로 아동들의 언어적 상호작용의 빈도가 증가하고 있었다. 또한 성취수준에 관계없이 활발한 상호작용이 일어나고 있음을 알 수 있었다.

• 만화애니메이션 연구
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• 통권17호
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• pp.188-204
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• 2009

본 연구는 3차원 컴퓨터 그래픽 제작 산업분야에서 최근 가장 경쟁력 있는 분야로 대두되고 있는 연구/개발(R&D) 분야에서 "불의 표현을 중심으로 국내 관련업체들의 기술적 한계를 제시하고 해외 및 국내 애니메이션 제작에서 성공한 기술적 R&D의 과정과 그 결과를 통해 이러한 기술적 한계를 어떻게 극복해야 하는지에 대한 해답을 제시함으로써 과도기를 거쳐 제2의 도약기를 준비하는 국내 컴퓨터 그래픽 애니메이션 산업의 부흥에 도움이 되고자하는 목적으로 연구를 진행하고 있다. 흔히 CT와 IT의 상호 보완적인 특징을 활용한다면 이러한 문제 해결을 넘어 기술적 우위를 확보할 수 있다. 우리는 특히 컴퓨터 그래픽 제작 과정 중 물, 불, 바람, 구름 등의 Simulation System분야와 수십만 캐릭터의 집단행동 또는 단체행동 System 활용도를 중심으로 연구를 진행하였다. 그 중에서 본 논문은 불의 표현에 중점을 두고 실제 작업에 활용된 데이터를 기준으로 그 해답을 제시하였으며 기존의 국내에서 사용하던 전통적 활용방법과 각 연구단체에서 활발하게 진행 중인 프로젝트를 소개하고 본 연구의 적용과정과 결과를 소개함으로써 현업 종사자들에게 향 후 R&D 분야의 나아갈 방향을 제시하고자한다. 창조적인 부재에 너무 집착한 나머지 기술적인 연구 개발부분에의 소홀함이 향 후 미국이나 일본과의 더 큰 기술적 문제로 대두될 수 있음을 명심하고 지금부터라도 과감하고 결단력 있는 기술력의 연구 개발이 필요한 시점이다.

• The Journal of Advanced Prosthodontics
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• 제10권4호
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• pp.271-278
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• 2018

PURPOSE. The purpose of this in vitro study was to evaluate the effect of abrasive toothbrushing on the surface properties of monolithic computer-assisted design and computer-assisted manufacturing (CAD/CAM) materials stored in food-simulating liquids (FSLs). MATERIALS AND METHODS. Fourty-eight disk-shaped test specimens of each material (Paradigm MZ100/PMZ, Lava Ultimate/LU, Vita Enamic/VE, and Vita Mark II/VMII) with a diameter of 10.0 mm and a thickness of $3.0{\pm}0.05mm$ were prepared. Specimens were divided into 4 subgroups (n=12) and stored in air, distilled water, 0.02 M citric acid, or 75% ethanol/water solution for 7 days at $36.5^{\circ}C$. Then, the specimens were brushed in a multi-station brushing machine under a vertical load of 2.0 N for 3 hours. Surface gloss (GU), roughness (Ra), and hardness (Vickers [VHN]) were measured after storage and brushing simulation. The data sets were statistically analyzed with 2 and 3-way ANOVAs followed by the Tukey's post-hoc comparisons (${\alpha}=.05$). RESULTS. Statistically significant difference was found among the materials concerning the results of surface properties. VMII showed the highest VHN, while PMZ produced the lowest. Storage in FSLs significantly affected the VHN of PMZ and LU. VMII showed the lowest Ra and highest GU irrespective of FSLs and of abrasive toothbrushing. VE, LU, and PMZ produced significant decrease in GU and increase in Ra after toothbrushing. CONCLUSION. Surface properties of monolithic CAD/CAM restorative materials were differently affected by the storage media and abrasive toothbrushing.

• 한국지진공학회논문집
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• 제7권6호
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• pp.1-7
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• 2003

이 논문에서는 비선형 지반-구조물 상호작용해석을 위한 새로운 시간-주파수영역 복합법을 제시하였다. 제안한 방법은 등가선형 지반-구조물 상호작용해석 프로그램과 범용 비선형 유한요소해석 프로그램을 동시에 사용하는 실용적인 방법이다. 이 방법에서는 먼저 주파수영역에서 등가선형 지반-구조물 상호작용해석을 수행하여 유한요소 영역의 경계면에서 응답을 구한 다음, 이를 범용 비선형 유한요소해석 프로그램에 의한 비선형 동적해석의 시간의존 경계조건으로 입력한다. 제안된 방법의 검증을 위하여 2차원 지하철 정거장 구조물에 대한 지진해석을 수행하였다. 이를 위하여 등가선형 지반-구조물 상호작용해석 프로그램 KIESSI-2D와 비선형 유한요소해석 프로그램 ANSYS를 사용하였다 수치적인 해석결과로부터 이 연구에서 제안한 방법의 타당성을 확인할 수 있었다.

• 대한치과기공학회지
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• 제33권4호
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• pp.271-281
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• 2011

Purpose: The aim of this study is to investigate the changes in hardness and microstructure of a dental multipurpose alloy after simulated complete firing with controlled cooling rate and holding time by characterizing the changes in hardness and microstructure after simulated firing with various cooling rates and holding times. Methods: Before hardness testing, the specimens were solution treated and then were rapidly quenched into ice brine. The specimens were completely fired in furnace. Hardness measurements were made using a Vickers microhardness tester. The specimens were examined at 15 kV using a field emission scanning electron microscope. Results: The maximum hardness value was obtained at stage 0 after simulated firing with various cooling rates (quick cooling, stage 0, stage 1, stage 2, stage 3). By the repetitive firing, the hardness of the tested alloy decreased gradually. By holding the specimen at $500^{\circ}C$ for 10-20min after simulated firing, the hardness increased apparently. However, to hold the alloy for long periods of time in the relatively high temperature after simulated firing resulted in the formation of thick oxidation layer. The oxide film formed on the surface of the alloy after simulated complete firing with controlled cooling rate, which was mainly composed of O and Zn. Conclusion: It is reasonable to hold the alloy at $500^{\circ}C$ for 10-20min after complete firing in other to improve the final hardness of the alloy.

• 대한간호학회지
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• 제37권3호
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• pp.313-323
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• 2007

Purpose: Health-related quality of life (HRQOL) in patients with cardiovascular disease in Korea has rarely been studied, mostly due to the lack of a psychometrically validated disease-specific instrument. The purpose of this study was to develop and validate a cardiovascular specific-HRQOL questionnaire (CD-QOL). Method: The CD-QOL was developed and validated as follows; item generation, pilot study, and psychometric tests. Patients were recruited from three-university hospitals. The patients were asked to complete the preliminary questionnaire comprising the content-validated items, SF-36, and CES-D. The NYHA and KASI classifications were used to classify the functional performance of the patients. The data was analyzed using correlation, factor analysis, multidimensional scaling, multitrait/multi-item matrix, ANOVA, and Cronbach's alpha. Result: Preliminarily, thirty-nine items were generated. Factor analysisextracted a five-factor solution with a total of twenty-two items. One item was deleted based upon the MDS. The remaining items were moderately correlated with the subscales of the SF-36 and associated with depression measured with the CES-D. The mean scores of patients in NYHA and KASI class I were significantly higher than those in NYHA and KASI class II or/and III, which suggested patients with better functional performance were likely to have a better HRQOL. Cronbach's alphas of the total and subscales were all greater than 0.70. Conclusion: The CD-QOL is a easily applicable instrument with excellent psychometric properties of content, criterion, factorial, convergent, and known-groups validity, and internal consistency reliability in Korean patients with cardiovascular disease.

• Restorative Dentistry and Endodontics
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• 제20권1호
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• pp.113-128
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• 1995

The purpose of this study was to investigate the effect of stannous fluoride on the dentin bonding with three kinds of commercially available dentin bonding systems containing different adhesive monomers. Dentin specimens with exposed labial dentin prepared from freshly extracted bovine mandibular anterior teeth were divided into experimental and control groups. The specimens of experimental groups were bonded with dentin bonding systems and composite resins including All bond 2 ㅡ& Bisfil, Scotchbond Multi-Purpose & Z100, and Denthesive II Charisma after 2 % stannous& fluorided application for S minutes and washing for 1 minute. The specimens of control groups were bonded with the same dentin bonding systems and composite resins as used in the experimental groups. After bonded specimens were stored in $37^{\circ}C$ distilled water for 24 hours, the tensile bond strength and cohesive failure rate were measured, and then the pretreated dentin surfaces and the fractured dentin surfaces were examined under scanning electron microscope. The results were as follows : Mean bond strength of stannous fluoride applied groups of All bond 2, Scotchbond MP, and Denthesive II were 2.5MPa, 1.1MPa, and 1.1MPa respectively, and those of control groups were 7.5MPa, 8.1MPa, and 4.6MPa. Bond strength values of stannous fluoride applied groups were significantly lower than those of the control groups(p<0.05). SEM findings of dentin surfaces after stannous fluoride application demonstrated an appearance of partially remained smear layer and smear plugs inspite of pretreatment with 10 % phosphoric aicd or maleic acid solution, and an appearance of smear layer covered surface under Denthesive II priming. But those of control groups commonly showed clean dentin surfaces without smear layer and smear plugs. On SEM observation of the fractured dentin-resin interface, while most of the specimens of stannous fluoride applied groups showed adhesive failure mode, those of All bond 2 and Scotchbond MP control groups showed mainly adhesive-cohesive mixed failure mode, and mainly adhesive failure mode in Denthesive II control group.

• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.447-463
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• 1997

The purpose of this study was to evaluate the effectiveness of copal varnish and five bonding agents(Scotchbond Multi-Purpose Plus Dental Adhesive System, Panavia 21, All Bond 2, Superbond D-Liner II plus, Fuji Duet) in reducing microleakage under amalgam restorations. Class V cavity were prepared on both buccal and lingual surface of sixty extracted human molars with cementum margin and were filled with different kinds of liners and amalgam. All teeth were stored at $37^{\circ}C$ in physiologic saline solution. After 1 week they were thermally stressed for 500 cycles between 5 and $55^{\circ}C$ in baths containing 0.5 % basic fuchsin dye. The dye penetrations were observed with a stereomicroscope. Scanning electron micrographs were taken of representative tooth sections from each group to assess the nature of the tooth/liner/amalgam interface. The statistical test were applied to the results using a one way analysis variance (ANOVA) and Duncan's multiple range test. The results were as follows ; 1. In all groups, the enamel margin showed significantly lower leakage value than the cementum margin (p<0.05). 2. At the dentin and enamel margins, the leakage value of Copalite-lined group showed significantly higher than that of no liner group (p<0.05), but showed significantly lower than that of bonding agent lined-groups (p<0.05). 3. There was no significant difference between the bonding agent lined-groups (p>0.05). 4. On the backscattered scanning electron microscopy observation, discontinuous gaps were observed between amalgam and dentin in the bonding agent-lined amalgam restorations and the bonding agents appeared to fill the gap space and were mixed with amalgam particles. At the amalgam/tooth interface, unsealed dentin and continuous gaps were found in both unlined and Copalite-lined restorations.

• Restorative Dentistry and Endodontics
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• 제26권2호
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• pp.153-161
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• 2001

The purpose of this study was to evaluate microleakage of six current dentin bonding systems. In this in vitro study, class V cavities were prepared on buccal and lingual surfaces of thirty extracted human molars. Each margin was on enamel and dentin/cementum. Experimental teeth were randomly divided into six groups of 5 each. Group 1 : Scotchbond Multi-Purpose; Group 2 : Single Bond; Group 3 : Prime&Bond NT ; Group 4 : Clearfil Liner Bond 2 ; Group 5 : MAC Bond II ; Group 6 : One-up Bond F. The bonding agent and composite resin were applied to class V cavities according to manufacturer's directions. After thermocycling, the specimens were immersed in 0.5% basic fuchsin dye solution for 6 hours and sectioned longitudinally through the center of the restoration with a low speed diamond saw. The degree of microleakage was measured as the extent of dye penetration under the stereomicroscope at $\times$20. The data were analyzed using one way ANOVA. When significant differences found. multiple comparisons were made using Duncan's Multiple Range Test. The results of this study were as follows: 1. In all groups, leakage value seen at the enamel margin was significantly lower than that seen at the dentin margin(P<0.001). 2. At the enamel margin, none of the dentin bonding systems used in this study showed statistically significant difference in leakage values(P<0.05). 3. At the cementum margin, group 3 showed the highest leakage value, and others were decreased as group 5, 6, 4 in that order, and group 1, 2 showed the lowest leakage value. There was statistically significant difference between group 3 and the other groups except for group 5(P<0.05).