• 대한기계학회논문집A
• /
• 제21권9호
• /
• pp.1531-1540
• /
• 1997

Mordern industrial society pursues unmanned system and automation of manufacturing process. Abreast with this tendensy, production of goods which requires advanced accuracy is increasing as well. According to this, the work sensing time of dressing by monitoring and diagnosing the condition of grinding, which is th representative way in accurate manufacturing, is an important work to prevent serious damages which affect grinding process or products by wearing grinding wheel. Computer vision system was composed, so that grinding wheel surface was acquired by CCD camera and the change of cutting edge ratio was measured. Then we used automatic thresholding technique from histogram as a way of dividing grinding cutting edge from grinding surface. As a result, we are trying to approach unmanned system and automation by deciding more accurate time of dressing and by visualizing behavior of grinding wheel by making use of computer vision.

• 한국산림과학회지
• /
• 제106권1호
• /
• pp.1-9
• /
• 2017

산림 벌채 후 형성되는 가장자리 효과의 발생 여부과 회복 과정을 이해하는 것은 생태계 천이와 경관 및 서식지의 공간 영향을 분석하고 이해하는 필수 요소임에도 불구하고, 우리나라에서 관련 주제의 실증 연구는 찾아보기 어렵다. 본 연구는 강원 남부 지역의 소나무림 벌채 후 1, 3, 10, 16년이 경과한 장소에 형성된 벌채지 및 임내 가장자리에서 비생물 및 생물 요인의 변화 양상을 선 (20개) 및 방형구 (340개) 조사법을 병용하여 조사하였다. 벌채 후 초기(3년 이내)는 가장 자리에서 인접 숲 내부 방향으로, 15m 깊이까지 식생 피도, 풍부도, 수관 열림도, 그리고 대기 온도 및 습도가 급격하게 변화하였다. 가장자리 형성 이후, 비생물 요인 및 식물 풍부도의 안정화는 각각 10년 및 16년이 소요되었다. 교목종이 초본식물에 비하여 가장자리 환경에서 더 높은 증가 양상을 나타내었고, 교목종의 높은 증가는 하층식생의 동태에 영향을 주었다. 본 연구 결과를 통해 벌채에 의한 직 간접적인 서식지 변화는 최소 인접 산림의 15 m에서 20 m까지, 그리고 16년 수준까지 지속적으로 영향을 미치는 것으로 나타났다. 본 연구 결과는 경관 및 서식지 패치 평가에 필수적인 가장자리 효과의 깊이에 대한 첫 국내 첫 실증 연구자료로 친환경벌채 기준제시 등 활용성이 높다.

• 한국정밀공학회지
• /
• 제31권3호
• /
• pp.207-213
• /
• 2014

A study was carried out to fabricate the cutting tool geometry with micro/nanoscale on the single crystal diamond tool by using the FIB. The FIB technique is an ideal tool for TEM sample preparation that allows for the fabrication of electron-transparent foils. The FIB is appropriate techniques to sample and subsequently define the chemical composition and the structural state of mineral inclusion on the micro/nanoscale. The combination of FIB with a SEM allows for 3D information to be obtained from samples including 3D imaging. Cutting strategies were demonstrated to improve the performance of cutting tool geometry and to generate high aspect ratio micro cutting tool. A finely focused beam of 30keV Ga+ ions was used to mill cutting tool shapes for various micro patterns. Therefore FIB sputtering is used to shape a variety of cutting tools with dimensions in the $1-5{\mu}m$ range and cutting edge radii of curvature of under 50nm.

• 한국정밀공학회지
• /
• 제14권3호
• /
• pp.122-129
• /
• 1997

Machining technology has emerged to the point of performing atomic-scale fabrication. In tail paper atomic-scale machining characteristics are investigated by using Molecular Statics simulation method. The cutting model used in this work simulates machining with tools such as an AFM. It is shown that built-up edge formation and cutting forces depend on tool tip geometry. Also, the material flow during cutting is shown for various cutting conditions such as depth of cut, rake angle, and edge radius of tool.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 추계학술대회 논문집
• /
• pp.911-914
• /
• 1997

This Experiment was carried out for bur minimization in drilling. New drill geometries are proposed to minimize the burr formation in drilling operation. Three types of drills are made, champer, round and step drill. The burr formed in first cutting by front cutting edge ca be removed in second cutting by the cutting edges in chamfer, round edge and step. New burrs are formed by second cutting and can be minimized according to the change of drill geometry like, chamfer size and angle, corner radius in round drill and step size and angle in step drill. To measure the burr formed in drilling, laser sensor is used.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
• /
• pp.344-348
• /
• 2001

In this study, experiments were carried out to investigate the characteristics of grinding and wear process of diamond wheel grinding ceramic materials. Normal component of grinding resistance was decreasing while increase of spindle speed. The resistance of vitrified bond wheel was less then that of resinoid bond wheel because of imbedded large holes on the surface of cutting edge. Surface roughness was decreasing while increase of spindle speed. The surface roughness after using vitrified bond wheel was less than that of resinoid bond wheel because of small elastic deformation. After continuous grinding of ceramics, cutting edge ratio of resinoid bond wheel decreases. For the case of vitrified bond wheel, cutting edge ratio does not change.

• 대한기계학회논문집
• /
• 제18권7호
• /
• pp.1643-1653
• /
• 1994

To facilitate the manufacturing of dull using CNC grinding machine, the simulation of helical groove machining with given wheel profile and setting condition is necessary. Considering the wheel as a collection of thin disks, the flute configuration is predicted in a cross section perpendicular to the axis and the grinding wheel profile is also predicted to machine the desired helical groove with given setting conditions. Two programs for these processes are developed. Using programs interactively, the helical groove machining process can be predicted more accurately. By clarifying the geometrical relation between the shape of cutting edge and the flute configuration in the cross section which is perpendicular to drill axis, it becomes possible to predict the necessary cross sectional shape of wheel for desired drill cutting edge shape. Some factors for the software are considered concerning prediction of accuracy and computing time.

• 한국공작기계학회논문집
• /
• 제13권1호
• /
• pp.16-21
• /
• 2004

In order to investigate the characteristics of diamond wheel grinding of ceramic materials, grinding resistance, surface roughness of ground surface and image of grinding wheel were acquired using experimental method. Through the experiments, this makes it possible to observe grinding wheel behavior by grinding resistance, surface roughness and cutting edge ratio. In case of $Al_2O_3$, cutting edge ratio is bigger than that of $ZrO_2$ and $Si_3N_4$. That's because $Al_2O_3$ has a characteristic of low fracture toughness and bending stress.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2002년도 추계학술대회 논문집
• /
• pp.308-313
• /
• 2002

In order to investigate the characteristics of grinding and diamond wheel grinding ceramic materials, grinding resistance, surface roughness of worked surface and image of grinding wheel were acquired using experimental method. Through the experiments, this makes it possible to observe grinding wheel behavior by grinding resistance, surface roughness and cutting edge ratio. In case of A1$_2$O$_3$, cutting edge ratio is begger than that of ZrO$_2$and Si$_3$N$_4$. That's because A1$_2$O$_3$has a characteristics of low fracture toughness and bending stress.

• 한국기계가공학회지
• /
• 제13권2호
• /
• pp.108-116
• /
• 2014

Considering the run-out effect and cutting force coefficients, the cutting force profile of half immersion end-milling was analyzed in detail. The effects of three specific cutting-force coefficients and three edge-force coefficients are verified. Through a detailed investigation, it is proved that the radial cutting force coefficients and are the major factors which increase the cutting forces Fx and Fy in end-milling. However, the axial cutting force coefficients have no influence on the force Fx and Fy changes in end-milling. Also, the analyzed end-milling force model shows good consistency with the actual measured force with regard to Fx and Fy. Thus, this model can be used for the prediction of the force history in end-milling with run-out, and it incurs a different force history with different start and exit immersion angles as well as holding effects.