• 한국CDE학회논문집
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• 제14권1호
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• pp.18-24
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• 2009

This paper proposes an analytical method of evaluating the maximum error by modeling the exact tool path for the tool traverse singular region in five-axis machining. It is known that the NC data from the inverse kinematics transformation of 5-axis machining can generate singular positions where incoherent movements of the rotary axes can appear. These lead to unexpected errors and abrupt operations, resulting in scoring on the machined surface. To resolve this problem, previous methods have calculated several tool positions during a singular operation, using inverse kinematics equations to predict tool trajectory and approximate the maximum error. This type of numerical approach, configuring the tool trajectory, requires much computation time to obtain a sufficient number of tool positions in a region. We have derived an analytical equation for the tool trajectory in a singular area by modeling the tool operation into a linear and a nonlinear part that is a general form of the tool trajectory in the singular area and that is suitable for all types of five-axis machine tools. In addition, we have evaluated the maximum tool-path error exactly, using our analytical model. Our algorithm can be used to modify NC data, making the operation smoother and bringing any errors to within tolerance.

• 한국정밀공학회지
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• 제15권11호
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• pp.137-144
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• 1998

In this paper we present our research dealing with the problem of tool deflection during the milling. We try to compensate the errors by considering a new tool trajectory. In order to determine the compensated tool trajectory, the problem is divided in three steps : cutting forces model, tool deflection model and trajectory compensation. Starting from experimental data, we determine a cutting forces model., which allows us to anticipate the tool deflection along one nominal path. In order to determine the compensated tool trajectory, we propose in this paper a method of path compensation, called “mirror method”. This method of tool path optimization allows to minimize errors due to tool deflection. Several examples are processed in simulations and validated experimentally.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제15권3호
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• pp.145-153
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• 2009

궤적(trajectory) 데이타는 실세계 어디에서든지 쉽게 찾아볼 수 있다. 최근 들어, 위성, 센서, RFID, 비디오 및 무선 통신 기술의 발전으로 말미암아 이동 객체를 체계적으로 추적하고, 많은 양의 궤적데이타를 수집할 수 있게 되었다. 이에 따라, 궤적 데이타의 분석에 대한 필요성이 점차 증대되고 있다. 본 논문에서는 대규모 궤적 데이타를 위한 마이닝 툴을 개발한다. 본 마이닝 툴에서는 가장 널리 사용되는 마이닝 연산인 집단화(clustering), 분류(classification), 이상치 발견(outlier detection)을 제공한다. 궤적 집단화는 공통적인 이동 패턴을 발견하며, 궤적 분류는 궤적에 기반하여 이동 객체의 범주를 예측하며, 궤적 이상치 발견은 나머지 궤적들과 크게 다르거나 일관적이지 않은 궤적을 발견한다. 본 마이닝 툴의 가장 큰 장점은 데이타 마이닝 도중에 부분 궤적 정보를 활용한다는 점이다. 본 마이닝 툴의 우수성은 다양한 실제 궤적 데이타 셋을 사용하여 입증되었다. 본 논문의 결과로 궤적 데이타 마이닝을 위한 실용적인 소프트웨어를 개발하였고 많은 실제 응용에 적용될 수 있을 것이라 사료된다.

• 산업공학
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• 제22권1호
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• pp.17-25
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• 2009

In mobile device's user interface, menu organization is very important as well as menu structure because small display of mobile device. Menu items should be organized based on user knowledge structure to design user-centered interface. Traditionally, MDS (Multidimensional Scaling) have been most often used to expose users' perceived organization of menu items. But, information that MDS reveals is just relative spatial location of concepts and not relevant to concepts connection. Unlike MDS, Trajectory Mapping explicitly finds users' cognitive links between perceived concepts. This study proposes a Trajectory Mapping technique for eliciting knowledge structure, especially a set of cognitive pathways linking menu items, from end user. With twelve participants, MDS and Trajectory Mapping were conducted using cellular phone's menu items. And user knowledge structure was analyzed through Visual Concept Map that combination of results of MDS and Trajectory Mapping. After then, menu items were organized according to users' perceived organization. Empirical usability test was also conducted. The results of usability test showed that usability, in terms of task performance time, number of errors, and satisfaction, for newly organized interface was significantly improved compare to original interface. The methodology of this study is expected to be applicable to design a user-centered interface. In other words, Trajectory Mapping technique can be used as a design tool of user interface for imposing user knowledge structure on the interface.

• 한국생산제조학회지
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• 제24권4호
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• pp.374-385
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• 2015

In this paper, effective and user friendly CAM software is presented that automatically generates any three dimensional complex toolpaths according to a CAD drawing. In advanced manufacturing, often it is essential to scan the sample following a complex trajectory which consists of short (few microns) and multidirectional moves. The reported CAM software offers constant velocity for all short trajectory elements and provides an efficient shift of tool path direction in sharp corners of a tool trajectory, which is vital for any laser, based precision machining. The software also provides fast modification of tool path, automatic and efficient sequencing of path elements in a complicated tool trajectory, location of reference point and automatic fixing of geometrical errors in imported drawing exchange files (DXF) or DWG format files.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.186-188
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• 1995

In this paper, Cross-Coupled Controller proposed for multi axes servo system. Tracking error and contouring error exist when a machine tool moves along the trajectory in multi exes system. The proposed scheme enhances the contouring performance by reducing contour error. Feedforward compensator reduces the effects of a nonlinear disturbance such as friction or dead zone. The proposed control scheme reduces the contour error which occured when the tool tracks the reference trajectory. Simulation results show that this scheme improves the contouring performance along the reference trajectory in XY-table.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 추계학술대회 논문집
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• pp.88-93
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• 1997

Ball-end milling process is widely used in the die and mold manufacturing because of suitable for the machining of free-form surface. Pencil cutting can eliminate overload in uncut area caused by large diameter of ball-end mill before finish cutting. As the ball-end mill for pencil cutting is long and thin, it is easily deflected by cutting force. The tool deflection when pencil cutting is one of the main reason of the machining errors on a free-from surface. The purpose of the research is to find out the characteristics of deflected cutter trajectory by eddy-current sensor.

• 한국공작기계학회논문집
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• 제13권5호
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• pp.96-102
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• 2004

In this study, we have developed the simulation tool in order to investigate driving trajectory of AGV for container transport. AGV for container transport is different from the indoor AGV in that it is a large size structure at being loaded the weight of 40 ton. and AGV for container transport is applied to front wheel steering, rear wheel steering, all wheel steering, and crap steering. Therefore, we have developed the simulation tool considering dynamic problems and a center of turning in accordance with fourth ways of steering mode. As the result of this study, we have confirmed that this tool is useful and cost-effective in the dynamic analysis or large size vehicles. Also, it is useful to calculate the minimum radius of turning for large size vehicles.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.482-487
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• 2002

This paper presents a robot trajectory generation method based on the dual curvature theory of ruled surfaces. Robot trajectory can be represented as a ruled surface generated by the TCP(Tool Center Point) and my unit vector among the tool frame. Dual curvature theory of ruled surfaces provides the robot control algorithm with the motion property parameters. With the differential properties of the ruled surface, the linear and angular motion properties of the robot end effector can be utilized in the robot trajectory planning.

• 한국정밀공학회지
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• 제30권9호
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• pp.961-968
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• 2013

In this paper, we propose an optimal design for starfish capturing manipulator module with four-bar linkage mechanism. A tool link with compliance is attached on the four-bar linkage, and the tool repeats detaching starfish from the ground and putting it into the storage box. Since the tool is not rigid and the manipulator is operating underwater, the trajectory of the tool tip is determined by its dynamics as well as kinematics. We analyzed the trajectory of the manipulator tool tip by quasi-static analysis considering both kinematics and dynamics. In optimization, the lengths of each link and the tool stiffness are considered as control variables. To maximize the capturing ability, capturing stroke of the four-bar manipulator trajectory is maximized. Reaction force and reaction moment, and other kinematic constraints were considered as inequality constraints.