• 대한치과보철학회지
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• 제42권2호
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• pp.142-153
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• 2004

Statement of problem: Increasing demand of esthetic restorations made lots of kinds of ceramic materials. Among them, zirconia has been being focused by many dentists. But, mechanical properties of zirconia were still unclear. Purpose : The purposes of this study were to analyze the flexural strength of various zirconia ceramics which had been currently used for clinic i.e., In-Ceram Zirconia(Vita Zahnfabrik, Bad $S\"{a}ckingen$, Germany), Celay Zirconia(Vita Zahnfabrik, Bad $S\"{a}ckingen$, Germany) and CAD/CAM Zirconia (Adens Zi-Ceram. Seoul , Korea). Material and methods: The four point bending test(ASTM Cl161) was used to measure the flexural strength of a specimen before and after circular heat treatment and fatigue loading. Results : 1. The average value of flexural strengths of CAD/CAM Zirconia, Celay Zirconia, In-Ceram Zirconia in dry condition were 806.5 MPa, 669.9 MPa, 605.6 MPa, respectively. There was a statistically significant difference in strength among the types (P<0.05). 2. After thermocycling, the average flexural strengths of CAD/CAM Zirconia, Celay Zirconia, In-Ceram Zirconia were 791.2 MPa, 604.2 MPa, 605.4 MPa, respectively. CAD/CAM Zirconia showed statistically significant higher strength(P<0.05). The others showed no significant difference after thermocycling(P>0.05). 3. After fatigue loading in wet condition. the average flexural strengths of CAD/CAM Zirconia, Celay Zirconia, In-Ceram Zirconia were 806.0 MPa, 674.9 MPa, 601.7 MPa, respectively. There was a significant difference in strength among the types(P<0.05). 4. There was no statistically significant difference in strength of the specimens according to experimental methods except for before and after thermocycling in Celay Zirconia(P>0.05). Conclusion: Besides high esthetic quality, zirconia had sufficiently high mechanical strength.

• 한국멀티미디어학회논문지
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• 제3권1호
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• pp.63-76
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• 2000

기존의 CSCW (Computer Supported Collaborative Work) 시스템은 단순히 문서나 메시지를 구성하고 전달하는 기능만을 지원할 뿐 협동 작업자들간의 조직구성, 업무분할 및 통합, 작업흐름 제어와 같은 인지학적 기능등은 효과적으로 반영하지 못하고 있다. 본 연구는 협동작업환경에서의 CAD(Computer Aided Design)/CASE(Computer Aided Software Engineering)와 같은 공학 디자인 프로세스를 인지학적으로 지원하기 위한 CSCW 시스템을 개발하는 데 그 목적이 있다. 제안된 DCWA (Distributed Collaborative Writing Aid) 시스템은 CAD/CASE 및 시뮬레이션 기능을 하나의 시스템으로 통합함으로써 조직구성, 업무분할, 작업흐름제어가 이들 기능에 통일적으로 적용될 수 잇도록 하였다. 특히 CAD 도구에서는 다중 사용자들 소유의 그림객체 간의 바인딩, 어태치먼트, 스케일링 기능들은 제공하여 결합 형태 및 정도를 나타내는 관계성 표현이 가능하도록 함으로써 업무분할 및 병합이 CAD 도구에서도 명확히 드러나도록 하였고, CASE 도구에서는 소프트웨어 시뮬레이션 기능과 연계하여 작업흐름 제어가 용이하도록 하였다. 이는 또한 제품을 생산하기 전에 미리 모형을 시뮬레이션 해봄으로써 제품 개발의 시간과 비용을 단축할 수 있는 효과를 가져다 준다.

• 중환자간호학회지
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• 제12권1호
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• pp.82-93
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• 2019

Purpose : The purpose of this study was to investigate the degree of post-traumatic stress disorder (PTSD) symptoms and the effect of PTSD on quality of life (QoL) among coronary artery disease (CAD) patients. Methods: The participants were 135 CAD patients who visited outpatient clinics in a university hospital in B city of Korea. Their PTSD symptoms and QoL were measured by structured questionnaires and analyzed with multiple hierarchical regression analysis. Results: Among the 135 participants, 20.7% were classified as moderate risk, and 3.7% as high risk for PTSD. PTSD symptoms were significantly higher in participants who were diagnosed with CAD within 6 months (t=26.02, p<.001). The physical component of health-related QoL was influenced by gender (${\beta}=-.25$, p =.003), recurrence of CAD (${\beta}=.21$, p =.008), and PTSD symptoms (${\beta}=-.33$, p <.001). The mental component of health-related QoL was influenced by religion (${\beta}=-.17$, p =.044), body mass index (${\beta}=.17$, p =.033), and PTSD symptoms (${\beta}=-.37$, p <.001). Conclusion: Patients who had had a CAD diagnosis for less than 6 months were found to be vulnerable to PTSD, and PTSD was found to have a negative impact on the physical and mental components of their QoL. It is necessary to develop an intervention program for the effective prevention and management of PTSD symptoms in patients with CAD.

• 대한치과기공학회지
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• 제40권1호
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• pp.1-8
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• 2018

Purpose: The purpose of this study is to evaluate the trueness and fitness of machined prostheses according to drill radius setting in CAD software. Methods: For this study, standard abutment were replicated in Type IV stone. The stone abutment were scanned using a dental scanner. The CAD design software was designed using scanned abutment data. When designing, the drill radius was set to 0.3 mm and 0 mm, respectively, and saved. The saved design data was milled using a milling machine (n=13). The inner surface of the milled crown was scanned. The trueness and fitness were measured using the inner scan data of prostheses. Independent t-tests were performed to identify significant differences in each data. Results: Trueness values of the data saved with 0.3 mm and 0 mm drill radius were $18.9{\pm}2.3{\mu}m$ and $19.1{\pm}0.9{\mu}m$, respectively. There was no statistically significant difference between the groups. Fitness values of the data saved with 0.3 mm and 0 mm drill radius were $65.5{\pm}0.8{\mu}m$ and $33.8{\pm}1.0{\mu}m$, respectively. There was a statistically significant difference between the groups (p<.05). Conclusion : Setting the drill radius is important to produce clinically good fit prostheses.

• Restorative Dentistry and Endodontics
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• 제23권2호
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• pp.618-629
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• 1998

CAD/CAM-fabricated ceramic restorations nowadays are used as alternatives of amlagam and posterior composite resin restorations, especially in the cases of inlay restorations. But the reported results on marginal and internal fit of CAD/CAM-fabricated ceramic inlay have showed considerable difference. In this study, to evaluate the marginal and internal fit of CEREC2-fabricated ceramic inlay restoration and to compare with the fit of gold inlay and amalgam restoration, standardized Class II MO cavities were prepared in forty extracted caries-free human premolars. The teeth with prepared cavities were divided into 4 groups of ten teeth each. In group 1, CEREC2-fabricated ceramic inlays were treated with Scotchbond Multi-Purpose Plus(SMP plus) and cemented with Scotchbond Resin Cement. In group 2, casted gold inlays were cemented in the same method as in group 1. In group 3, casted gold inlays were cemented with zinc-phosphate cement. And in group 4, the prepared cavities were restored with amalgam. Restored teeth were thermocycled, stored in 1% methylene blue for 24 hours, and sectioned faciolingually and mesiodistally using EXAKT. Sectioned surfaces were observed with stereomicroscope and the gaps were measured at 9 points of mesiodistally sectioned surface and 7 points of faciolingually sectioned surface. The measured data were treated by Kruskal-Wallis one way ANOVA and Student-Newman-Keuls test. 1. The differences among measured gaps at each points were statistically significant for 4 experimental groups (P<0.05). 2. There were statistically significant differences in the measured gaps at each points between group 1 and group 2, group 1 and group 3, group 1 and group 4, group 2 and group 4, and group 3 and group 4 (P<0.05). 3. There were not statistically significant differences in the measured gaps at each points between group 2 and group 3 (P>0.05). 4. In the cases of inlay restorations(group 1, group 2, group 3), the gaps at internal line angle(distopulpal, axiogingival, faciopulpal, linguopulpal line angle) had a tendency to increase. In the cases of amalgam restorations(group 4), the gaps at occlusal margin, gingival margin and axiogingival line angle were greater than those at the other parts of cavities. 5. In CEREC2-fabricated ceramic inlays which were treated with Scotchbond Multi-Purpose Plus and cemented with Scotchbond Resin Cement, the mean gaps were $111{\mu}m$ at cavity margins, $168{\mu}m$ at vertical walls of cavities, $225{\mu}m$ at internal line angles and $123{\mu}m$ at cavity floors.

• 대한치과의사협회지
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• 제52권1호
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• pp.17-26
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• 2014

Computerized 3D virtual dental models are currently available, and their use has started to improve treatment outcomes. The accuracy of digital models has been demonstrated by many studies and various intra-oral scanners are innovated for short scanning time and high precision. Recently, a digital model was combined with a high technology computer-driven system, which was developed for the application of a digital set-up and indirect bonding of lingual attachments. In this section, virtual treatment planning using a virtual set-up program is be introduced, and the clinical applications and accuracy of computer-generated indirect bonding are discussed.

• 복식
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• 제20권
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• pp.49-62
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• 1993

The purpose of this research was to utilize of Pattern Design System(P.D.S) by using AM-300 The conclusion were like these : 1. A coat of basic pattern was selected by design sketch. 2. The basic pattern was input into computer by digitizing. 3. The basic pattern was change into designed shape by using various skills. This system were enabled to draw straight lines, curves, delete lines, sections of lines, extend lines, cut pattern into sections, measure line or section reproduce whole pattern shape of section, rotate and mirror pattern and complete patterns. 4. Automatic grading of finished master pattern have been developed by creation and modification of grading rules of basic pattern. 5. Production pattern added seam allowance, not-ches was generated by P.D.S menu option. 6. Finished pattern design was plotted out 100% and 20% size by AM-300 Plotter. This results will be the basic materials to develop the CAD SYSTEM if some problems were improve. Furthermore, the utilization of P.D.S is expected to be developing in pattern making process.

• 대한산업공학회지
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• 제18권1호
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• pp.63-80
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• 1992

The concept of rapid prototyping intended for a significant reduction in cost and lead time becomes even more practical with the recent development of various equipments to make the concept concrete. For the purpose of real application of commercially available SLA(stereolithography apparatus), this paper is intended to develop the standard conversion procedure from CAD data to the input data for SLA. While the procedure presented in this paper is based on CAD system "CATIA" and SLA of 3D systems, Inc., which are being used in authors' company DAEWOO Motor Co., Ltd., the basic concept of this paper can be applied to any other CAD systems and machines of using stereolithography process. The algorithm presented in this paper is classified into two stages-node sampling and triangulation. First of all, point data are sampled through the node sampling procedure, and then these are triangulated so that the input data for SLA operation is finally generated. The suggested method is devised in a way to meet the input requirements of SLA and more importantly consume less computation time and generate less number of input data for SLA.

• Journal of Welding and Joining
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• 제9권2호
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• pp.11-19
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• 1991

1. 16bit 개인용 컴퓨터인 IBM-PC/AT수준에서 레이저 가공을 위한 임의의 도형을 입력하여 DXF File로 출력하고, External명령인 AutoCAM을 추가하여 AutoCAM의 실행이 가능하였으며 AutoCAM의 종료후에는 다시 AutoCAD로 작업이 가능하다. 2. 개발한 AutoCAM은 AutoCAD Ver 2.6i로부터 Release 10까지의 DXF File을 읽어 Graphic 출력이 가능하다. 3. 가공 경로를 NC프로그램이 임의로 선정가능하면서, 가장 능률적인 가공작업이 수행될 수 있 도록 연속 또는 최인접 도형요소를 자동 선정하고 이의 조건에 따른 Auto Mode의 NC프로그램 생성이 가능하다. 4. 생성된 NC프로그램을 레이저 가공기에 전송하여 가공실험을 실시한 결과, 생성된 NC 프로 그램은 거의 수정하지 않아도 작동이 가능한 정도의 만족할 만한 결과를 얻었으므로 실용화에 큰 문제가 없는 것으로 사료된다. 이상과 같이 레이저 가공을 위한 CAD/CAM시스템은 초심자등의 이용상의 편리를 위하여 대화식으로 하였으며 사용된 언어도 Quick BASIC으로 자체 개발하 였으므로 앞으로 이 분야의 연구 및 실용화를 위한 기초자료로 활용될 수 있을 것으로 사료된다.

• 대한치과의사협회지
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• 제54권3호
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• pp.191-197
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• 2016

In the past, restoration of implant crown, ready-made abutment produced by implant manufacturer could only be used. Using straight, angled abutment, there was a limit in adaptation multiple implants. Recently, with the development of implant and CAD/CAM technology, CAD/CAM customized abutment use has become possible which is different from the past when restoration was possible with only prefabricated abutment. Not only it makes emergence profile possible which is similar to natural teeth, but also it makes insertion path possible on CAD in multiple implant restorations. However, on anterior teeth which dental esthetics is very important, another restorations which are formed with natural colored gingiva area could be required. Titanium-based zirconia prostheses which have titanium connection and zirconia structure from 1mm above fixture platform are alternative. Therefore, the purpose of this review is to analyze the characteristics, advantages and disadvantages of the abutment which is used in multiple implant restorations, and to choose right abutment when clinical trials.