• 구강회복응용과학지
• /
• 제28권3호
• /
• pp.253-268
• /
• 2012

수직적, 수평적 골흡수가 심한 환자에서 임플란트를 이용한 전악수복의 경우 경조직과 연조직 이식을 통해서 임플란트를 원하는 위치에 식립할 수도 있지만, 치은과 치아의 기능과 심미를 회복할 수 있는 fixed detachable prostheses를 대체 술식으로 사용할 수도 있다. 이러한 증례에서 다양한 재료가 수복물의 제작에 사용 가능하지만, metal/acrylic 보철물에서는 레진치아의 파절 및 탈락이 일어날 수 있고, metal/ceramic 혹은 zirconia/ceramic 보철물에서는 도재의 chipping이나 파절과 같은 문제가 발생할 수 있다. 이에 최근에 심미적이면서도 기능적인 보철수복을 위해 zirconia에 도재를 축성하지 않고 임상적으로 적용가능한 monolithic zirconia framework이 출시되어 사용되고 있다. 본 임상 증례는 심미적인 요구도가 높은 완전 무치악 환자에서 임플란트를 식립하고 chipping이나 파절의 위험을 감소시키기 위해 monolithic zirconia framework을 이용해 만들어진 complete fixed detachable 보철물을 이용한 수복에 대해 보고하고자 한다. 이번 증례에서 보철물은 심미적, 기능적으로 만족스러웠으며, 2년 간의 정기검사에서 임상적인 합병증은 보고되지 않았다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 춘계학술대회 논문집
• /
• pp.881-888
• /
• 1997

A new algorithm for detection of tool fracture in milling process was developed. The variation of the peak-to-valley value of cutting load was used in this algorithm. Various kinds of vectors representing the condition of tool, such as tool condition vector, reference tool condition vector, tool condition variation vector were defined. Using these vectors, tool fracture index which represents the magnitude of tool fracture and is independent of tool run-outs is developed. Small and large tool fracture and chipping under various cutting condition could be detected using proposed tool fracture index, which was proved with cutting force model and experiments.

• 한국지구물리탐사학회:학술대회논문집
• /
• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
• /
• pp.162-169
• /
• 2003

Excavation by TBM can be characterized by a rock-machine interaction during the cutting process on a small scale, but on a large scale the interaction between the rock mass and TBM becomes very significant. For the planning and evaluation of TBM tunnelling it needs to understand rock fracture mechanism by a cutter or cutters on a small scale, and to estimate penetration rate, advance rate and utilization on a large scale. In this study rock chipping mechanism due to cutter-penetration is analysed by numerical simulation, showing that rock chipping is mainly occurred by tensile failure. Also, through the analysis of factors that affect on TBM procedures in various assessment systems, it is determined that the key elements that should be considered in the planning and evaluation of TBM tunnelling are classified into rock properties, the geological structures and properties of rock mass, and the structural and functional specifications of the machine. The user-friendly assessment tool is developed, so that penetration rate, advance rate and TBM utilization are evaluated from various input data. The tool developed in this study can be applied to a practical TBM tunnelling by understanding TBM tunnelling procedures.

• 한국생산제조학회지
• /
• 제6권3호
• /
• pp.17-25
• /
• 1997

This paper aims to clarify the effects of grinding conditions on the grinding force, ground surface and chipping size of workpiece in surface grinding of various ferrites with the resin bond diamond wheel. The main conclusions obtained were as follows: In a constant peripheral wheel speed, the specific grinding energy is fitted by straight lines with grinding depth coefficient($\delta$) in a logarithmic graph. The effect of both depth of cut and workpiece speed on grinding energy becomes larger in the order of Mn-Zn, Cu-Ni-Zn and Sr. When using the diamond grain of the lower toughness, the roughness of the ground surface becomes lower. The ground surfaces show that the fracture process during grinding becomes more brittle in the order of Sr, Mn-Zn and Cu-Ni-Zn. The chipping size at the corner of workpiece in grinding increases with the the increases of the depth of cut and workpiece speed, and the decrease of peripheral wheel speed. The effect of both depth of cut and workpiece speed on chipping size becomes more larger in the order of Sr, Mn-Zn and Cu-Ni-Zn.

• Tribology and Lubricants
• /
• 제13권4호
• /
• pp.18-25
• /
• 1997

The various deformation and fracture behaviors under light loads in soda-lime glass under sliding Vickers indentation have been studied. In soda-lime glass, deformation and fracture behaviors can be classified into four different patterns by applied load. At very light load (<0.1N), plastic deformation only occurred. At low loads (0.1~0.8N), median crack, appear. At intermediate loads (0.8~3.0N), median and lateral cracking occurred leading to a large chipping. At high loads (3.0~6.0N), a crushed zone was observed with median crack. The friction experiment finds that the increasing in the friction coefficients coincides with the onset of crushing in soda-lime glass.

• 한국생산제조학회지
• /
• 제9권1호
• /
• pp.96-101
• /
• 2000

Ceramic, PCD and CBN tools are available for the difficult-to-cut-materials such as hardened carbon tool steel, stainless steel, Inconel 718 and etc.. Ceramic toolsare likely to be chipped and abruptly broken before the appearance of normal wear in turning. Ther2efore ceramic tools are suitable for continuous cut in turning not for intermittent in milling. In this study, TiN/TiCN multi-layer coated ceramic tools were found to restrain the chipping, breaking and early fracture and to increase the critical cutting speed owing to TiN/TiCN multi-layer coating in Arc Ion Plating of PVD method.

• 대한기계학회논문집
• /
• 제17권1호
• /
• pp.27-37
• /
• 1993

본 연구에서는 공구의 파손 및 마멸량을 검출할 수 있는 시스템을 구축하고자 하였다. CCD(charge coupled device)카메라를 통해 공구형상의 영상을 얻고 이를 PC 로 분석하는 영상처리 기법과, 여기서 계산된 정보를 이용하여 패턴인식 기법으로 공 구의 상태를 판정하는 알고리즘을 개발하였다.

• 한국세라믹학회지
• /
• 제45권1호
• /
• pp.75-81
• /
• 2008

In this study, machining characteristics of AIN-hBN composites were evaluated in end-milling process. As a first step, AIN-hBN composite specimens with various hBN contents were prepared using hot press method. Material properties of the composites, such as relative density, Young's modulus and fracture toughness, were measured and compared. Then, a series of end-milling experinients were performed under various cutting conditions by changing cutting speed, depth-of-cut and feed rate. Cutting force variations were measured using a tool dynamometer during the cutting experiments. Machined surfaces of the specimens were observed using SEM and a surface pro filer to investigate the surface integrity changes. The cutting force decreased with an increases of hBN content. The cutting process was almost impossible for monolithic AIN, owing to severe chipping. In contrast, at high content of hBN, surface damage and chipping decreased, and better surface roughness can be obtained.

• 대한기계학회논문집A
• /
• 제24권4호
• /
• pp.900-906
• /
• 2000

Ceramic, PCD and CBN tools are available for the difficult-to-cut-materials such as hardened carbon tool steel, stainless steel, Inconel 718 and etc. Ceramic tools are likely to be chipped and abruptly broken before the appearance of normal wear in turning. Ceramic tools are suitable for continuous in turning, not for intermittent in milling. In this study, TiN/TiCN multi-layer coated ceramic tools were found to restrain the chipping, breaking and early fracture and to increase the critical cutting speed owing to TiN/TiCN multi-layer coating in Arc Ion Plating of PVD method.

• 한국생산제조학회지
• /
• 제7권4호
• /
• pp.123-129
• /
• 1998

Ceramic and CBN tools are available for the difficult-to -cut-materials such as hardened carbon tool steel. stainless steel and etc. Ceramic tools are suitable for continuous turning cut, not for intermittent milling cut. Ceramic tools are likely to be chipped and abruptly broken before the appearance of normal wear in turning. In this study, TiN coated ceramic tools were found to restrain the chipping, breaking and early fracture and to increase the critical cutting velocity owing to TiN coating in PVD method.