• 대한기계학회논문집A
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• 제25권12호
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• pp.2009-2018
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• 2001

This paper presents a region offsetting algorithm for tool-path generation. The proposed region offsetting algorithm is developed by expanding the 'PWID offset algorithm [Choi and Park, 1999]'designed to offset a simple polygon. The PWID offset algorithm has three important steps; 1) remove 'local invalid ranges'by invoking a PWID test, 2) construct a raw offset owe and 3) remove 'global invalid ranges'by finding self-intersections of the raw offset cure. To develop a region offsetting algorithm, we modified the PWID offset algorithm by expanding the concept of the 'global invalid range'in the third step. The time complexity of the proposed algorithm is approximately Ο(n), where n is the number of points, and it is free of numerical errors for practical purposes. The proposed algorithm has been implemented and tested with various real regions obtained by intersecting a sculptured surface with a plane.

• 한국정밀공학회지
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• 제26권2호
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• pp.133-140
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• 2009

Presented in this paper is a method to generate round-endmill toolpaths for sculptured surfaces represented as a triangular mesh model. The proposed method is applicable in toolpath generation for ball-endmills and flat-endmills because the round-endmill is a generalized tool in three-axis NC (numerical control) milling. The method uses a wireframe model as the offset model that represents a cutter location surface. Since wireframe models are relatively simple and fast to calculate, the proposed method can process large models and keep high precision. Intersection points with the wireframe offset model and a tool guide plane are calculated, and intersection curves are constructed by tracing the intersection points. The final step of the method is extracting regular curves from the intersection curves including degenerate and self-intersected segments. The proposed method is implemented and tested, and a practical example is presented.

• 건강과 자연농업
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• 232호
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• pp.1-12
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• 2006

제2 8회 한국유기농업대회장에서/제11회 제주특별자치도 유기농업대회 개최/우리의 산야초-은방울꽃/과수나무 수확직후 토양검정을 하고 밑거름은 땅이 얼기 전에 주어야 좋다/벼 멀칭재배의 이론과 기술/협회 회관 착공식/'유기가공식품인증제' 도입/미국 통상정책의 두얼굴/쌀과 같은 위치서 감귤협상/두가지 비료로 유기농작물의 고품질 다수확 생산을 체계적으로 보다 쉽게 하는 방법/개정 친환경농업육성법 공포/온실작물들의 잿빛곰팡이병 관리/시설 내 병해의 발병 특성과 방제대책/중국 박람회 및 유기농장 연수기/'07년도 인증위원회 개최공고/중국 친환경농업의 평가와 시사점/친환경 유기낙농의 정착 방안/유기농업으로 이룬 쿠바의 낙원/유기질비료의 이해

• 한국기계가공학회지
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• 제3권2호
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• pp.25-31
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• 2004

Machinability in metal cutting processes depends on cutting input conditions such as cutting velocity, feed rate, depth of cut, types of work material and tool shape factors. In this study, to assess chip breaking characteristics of a turning process, an equivalent oblique cutting system to this has been established. And the equivalent effective rake angle was determined using side rake angle, back rake angle and side cutting edge angle of the tool. A non-dimensional parameter, Chip breaking index(CB), was used to assess Chip breaking characteristics of chip in conjunction with the equivalent effective rake angle. In case of positive rake angles of the equivalent effective rake, the back rake angle has little effect on the chip breaking characteristics however, in case of negative ones, the side rake angle has some effect on Chip breaking characteristics.

• 한국레이저가공학회지
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• 제13권4호
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• pp.14-20
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• 2010

Robot path generation and laser welding technology for manufacturing automotive body are studied. Laser welding and industrial robot systems are used with the robot based laser welding system. The laser system used in this study is 1.6kW Fiber laser, while the robot system is 6 axes Industrial robot (payload: 130kg). The robot based laser welding system is equipped with laser scanner system for remote laser welding. The laser source, robot and laser scanner system are used to increase the processing speed and to improve the process efficiency. The welding joints of steel plate are butt and lapped joints. The quality test of the laser welding are through the observation the shape of bead on plate and cross-section of welding part. The 3 dimensional laser welding for non-linear pipe welding line is performed. This paper introduces the robot based laser welding system to resolve the limited welding speed and accuracy of the conventional spot welding system.

• 한국기계가공학회지
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• 제3권1호
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• pp.72-78
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• 2004

In this paper, mechanical behaviors of developed pedicle screw system, made of bio-mechanical materials(Ti-6Al-4V, Grade 5), ale predicted using FEM analysis. As a first step, morphologic construction of normal Korean spines and surgical operation convenience are considered to design optimum pedicle screw system. In this step, various design variables are considered as design parameters to develop optimized models. As a next step, tension and bending tests are performed to improve the structural performance of the developed system using finite element method. In this step, required Static compression and bending test specifications by ASTM F-04 25 04 01 are applied to understand the bio-mechanical behaviors of the designed spinal implant system under various load types. As the results of this research, it is possible to develop efficient pedicle screw system, having enough rigidity and fixation to stand any spinal damage under allowable stress conditions.

• 한국기계가공학회지
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• 제16권3호
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• pp.1-8
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• 2017

Tool path generation is a part of process planning in 3D printing. This is done before actual printing by a computer rather than an AM machine. The mesh geometry of the 3D model is sliced layer-by-layer along the Z-axis and tool paths are generated from the sliced layers. Each 2-dimensional layer can have two types of printing paths: (i) shell and (ii) infill. Shell paths are made of offset loops. During shell generation, twists can be produced in offset loops which will cause twisted tool paths. As a twisted tool path cannot be printed, it is necessary to remove these twists during process planning. In this research, An algorithm is presented to remove twists from the offset loops. To do so the path segments are traversed to identify twisted points. Outer offset loops are represented in the counter-clockwise segment order and clockwise rotation for the inner offset loop to decide which twisted loop should be removed. After testing practical 3D models, the proposed algorithm is verified to use in tool path generation for 3D printing.

• 한국기계가공학회지
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• 제13권3호
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• pp.28-34
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• 2014

In this paper, we propose a trajectory tracking controller for a two-wheeled mobile robot (WMR) with nonholonomic constraints using a fuzzy sliding-mode controller-based hyperbolic function. The proposed controller is composed of two separate controllers. The sliding-mode controller is used for attitude control of the WMR, and the fuzzy controller-based hyperbolic function is designed to adjust the reach time of the sliding-mode control. Simulation results on a linear and a circular trajectory show that the proposed controller improves the control performance. The proposed controller reduces the reach time by as much as 47% compared to the controller proposed by Xie et al.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.944-947
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• 2000

Sculptured surface machining plays a vital role in the process of bring new products to the market place. A great variety of products rely on this technology for the production of the dies and moulds used in manufacturing. And, the use of CNC machines and CAD/CAM system has become a vital parts of product development process. The propose of this study is to investigate the effect of cutting parameters on the machinability such as surface roughness and cusp generated in the machining of sculptured surface on a three-axis CNC machining center using the CAD/CAM system. Experimental result showed that: In step down cutting, as the inclined angle of surface became smaller, the cusp height appeared higher. On the other hand, in step over cutting, as the inclined angle of surface became larger, the cusp height appeared higher. In the point of precision machining, step over cutting was more effective. For the minimization of cusp height, step down cutting was effective in larger inclined surface, but step over cutting in smaller inclined surface.

• 대한기계학회논문집A
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• 제27권8호
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• pp.1418-1425
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• 2003

In CAD systems, a surface to be machined is expressed by a series of curves, such as B-spline, Bezier and NURBS curves, which compose the surface and then in CAM systems the curves are divided into a large number of line or arc segments. These divided movement commands, however, cause many problems including their excessive size of NC data that makes almost impossible local adjustment or modification of the surface. To cope with those problems, the necessity of real-time curve or surface interpolators was embossed. This paper presents an efficient real-time tool-path generation method fur interpolation of NURBS surfaces in CNC machining. The proposed tool-path generation method is based on an improved iso-scallop strategy and can provide better precision than the existing methods. The proposed method is designed such that tool-path planning is easily managed in real-time. It proposed a new algorithm for regulation of a scallop height, which can efficiently generate tool-paths and can save machining time compared with the existing method. Through computer simulations, the performance of the proposed method is analyzed and compared with the existing method in terms of federate, total machining time and a degree of constraint on the scallop height.