• The Journal of the Korean dental association
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• v.54 no.2
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• pp.123-133
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• 2016

Currently increasing use of implants, especially in anterior implant esthetics has become a major concern for both the patient and dentist. In the case of thin biotype if the thickness of the gingival soft tissue is less than 2mm, human eye can detect differences of colors depends on underlying materials. The zirconia abutment can be use not only for better esthetics but also for the hygienic because it is less attractive for the plaque deposition when it compare to the metals. Zirconia itself has many advantages as a biomaterial but also has frequent mechanical problems when it use for abutment of internal connection implant. For prevention or reduction of mechanical failures, use of titanium-link with zirconia super-structure which part that connects directly into the implant can be a good alternative. In this literature, I would like to review the clinical considerations of use of titanium link - CAD/CAM zirconia abutment for dental implant in esthetically important areas.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.25 no.2
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• pp.109-126
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• 2016

According of the development and spread of CAD/CAM, a number of prostheses we have done had been replaced. Dental technicians have a difficulty reproducing natural color when producing these zirconia crowns. Difficulty reproducing natural color when producing these zirconia crowns. In my case, in the beginning of experimenting with zirconia, I had a hard time dealing with zirconia and I have tried solve these problems. Therefore, I would like to share Ko's coloring technique made of my effort with you.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.2
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• pp.380-384
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• 1993

In precision wire electrode discharge machining by CAD/CAM, it is the most important problem on machining method to determine the wire electrode offset amout from the accurate calculation of discharge gap in order to increase the machining accuracy, after fixing the main machining conditions such as machining speed, wire tension, coolant conductivity, gap vlotage. The present study shows the relationships between discharge gap and main machining conditions by means of a series of experiment concerned with the gap using the workpiece of STD 11, and suggests the experimental eguation to calculate the accurate wire electrode offset amount under the given machining conditions for spot workers.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.34-38
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• 1992

Geometry based CAD/CAM system is hard to achieve "net shape machining" For a net shape machining, the machining errors should be compensated by off-line CAD/CAM system followed by on-line control system. In this paper, we investigate an off-line compensation scheme for the machining errors due to tool deflection in contouring operation. The significance of the deflection errors is first shown, and a compensation is sought via modifying the nominal tool path. In modification, tool deflection amount is iteratively compensated until the deflection amount is iteratively compensated until the deflected path results in the desired contour within a tolerance. The path modification algorithm has been tested via computer simulation. The developed algorithm can be used as a postprocessor for the current CAD/CAM system based on geometric modeling as a means for enhancing the machining accuracy.

• Korean Journal of Computational Design and Engineering
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• v.4 no.1
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• pp.43-51
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• 1999

Producing the relevant information (features) from the CAD models of CAM, called feature recognition or extraction, is the essential stage for the integration of CAD and CAM. Most feature recognition methods, however, have problems in the recognition of intersecting features because they do not handle the intersection geometry properly. In this paper, we propose a machining feature recognition algorithm, which has a solid model consisting of orthogonal primitives as input. The algorithm calculates candidate features and constitutes the Intersection Geometry Matrix which is necessary to represent the spatial relation of candidate features. Finally, it recognizes machining features from the proposed candidate features dividing and growing systems using half space and Boolean operation. The algorithm has the following characteristics: Though the geometry of part is complex due to the intersections of design primitives, it can recognize the necessary machining features. In addition, it creates the Maximal Feature Volumes independent of the machining sequences at the feature recognition stage so that it can easily accommodate the change of decision criteria of machining orders.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.4
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• pp.32-42
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• 1989

An algorithm and its computer program are developed for the computer aided automatic conversion from 2 dimensional (2-D) design drawings to a 3 dimensional used to generate the tool path of NC machine. The algorithm and its computer program developed were applied to several real objects for their feasibility check and showed satisfactory results. As the results of this study, it was proved that a foundation work to prepare the data base for CAD/CAM integ- ration can be established so as to improve the productivity.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.249-254
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• 1987

This paper presents a new method for generating smooth free-form surface by local correction. B-spline surface is used for its convenience of local correction, and the direction of surface correction is fixed to the average-surface-normal direction. The surface to be corrected is approximated into a uniform cubic B-spline surface. Then, the smoothness (curvature arrows, iso-parametric lines) of the approximated surface is displayed with B-spline control points. When a control point near the region that needs correction is selected, a new point 1 mm higher than the original control point in the direction of the average surface normal is displayed. And the surface is corrected by giving the amount of control point movement interactively. Since the direction of correction is given by the program and the amount of correction is selected by the user, the method is called semiautomatic. sufficiently smooth surface can be obtained by this method. Examples are given to illustrate the method.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.3
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• pp.32-38
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• 2004

Recently, the system of high speed milling(HSM) is widely used for reducing the operation time and maximizing efficiency of work. The most research of high speed milling system is still leaves much to be desired. Specially the research of mass pocket high speed processing with high precision is the first and probably the last. So this paper showed mass pocket processing of high precision with a duralumin and then confirmed a cause of inferior goods through the CAD/CAM pattern simulation and experimentation. And this paper showed high speed processing system reduce the rate of inferior from this optimal pattern.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.2
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• pp.209-216
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• 1997

A feature is well known as a medium to integrate CAD, CAPP and CAM systems. For a part drawing including both simple geometry and compound geometry, a process plan such as the selection of process, machine tool, cutting tool etc. normally needs simple geometry data and non-geometry data of the feature as the input. However, a extended process plan such as the generation of process sequence, operation sequence, jig & fixture, NC program etc. necessarily needs the compound geometry data as well as the simple geometry data and non-geometry data. In this paper, we propose a feature data model according to the result of analyzing necessary data, including the compound geometry data, the simple geometry data and the non-geometry data. Also, an example of the feature data model in milling process planning is described.

• The Journal of the Korean dental association
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• v.47 no.12
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• pp.817-822
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• 2009

치과보철학 분야에서 컴퓨터를 이용한 기술의 발달로 치료 계획, 수술, 보철물 수복에 이르기까지 CAD-CAM의 광범위한 적용이 가능해지고 있으며, 비용과 시간의 절약으로 효율적인 진료가 가능하다는 점을 인지한 많은 회사들의 투자로 다양한 프로그램과 기계들이 소개되고 있다. 그러나, 이렇게 활발한 제품 개발에도 불구하고 아직 실제 임상으로의 적용은 보편화되었다고 보기는 어려운데, 가장 큰 이유는 정확도에 대한 의심과 복잡하다고 느껴지는 초기의 숙련 과정에 있다고 하겠다. 제작회사들의 보고에 따르면 컴퓨터를 이용하여 디자인하고 절삭하는 것이 기존의 주조 기술보다 더 정교하다고 하였으나, 실제 임상에서는 미세한 오차를 간과한 데서 오는 최종 결과물과의 차이를 얘기하는 임상가들이 있는 것이 현실이다. 또, 그 사용 재료에 있어서도 초기 티타늄 금속 재료에 이어 심미적 요구를 위한 알루미나, 보다 향상된 강도를 가진 지르코니아에 이르기까지 다양한 재료들이 쏟아져 나오고 있다. 이에 본 논문에서는 다양한 CAD-CAM 시스템 중 대표적인 것 중의 하나인 Nobel Biocare사의 $Procera^{(R)}$ 시스템을 중심으로 지르코니아 수복물에 관한 최신 정보를 제공하며, 그 다양한 치과적 적용을 누구나 쉽고 정확하게 사용할 수 있는 임상 증례와 함께 소개함으로써 실제 임상 적용에 도움이 되고자 한다.