• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.153-154
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• 2007

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.3
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• pp.44-52
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• 2004

This paper proposed a error compensation methodology for three-DOF translational parallel manipulator. The proposed method uses CMM (coordinate measuring machine) as metrology equipment to measure the position of end-effector. To identify the transform relationships between the coordinate system of the parallel manipulator and the CMM coordinate system, a new coordinate referencing (or coordinate system identification) technique is presented. By using this technique, accurate coordinate transformation relationships are efficiently established. According to these coordinate transformation relationships, an equation to calculate the compensating error components at any arbitrary position of the end-effector is derived. In this paper, Monte Carlo simulation method is applied to simulate the compensation process. Through the simulation results, the proposed error compensation method proves its effectiveness and feasibility.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.876-879
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• 1995

Parallel NC machines are a new generation of machine tools aimed at increasing maching accuracy and reducing part cycle time. In addition to their capacity to perform both milling and turning operations, these machine tools can perform multiple machining operations simultaneously,involving one or more parts at a time, and can completely finish a part in a single setup. Due to the lack of a computer-aided process planning system, these machines are used in industry today as dedicated, mass-production machines. This pape presents methodology for generating optimal process plan for each parallel machine tool using a genetic algorithm.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.8
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• pp.878-885
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• 2011

A kinematically-hybrid 5-axis machine tool is analyzed from the perspective of machine tool design. Its kinematic characteristics are pointed out, which should be considered during the conceptual design process. A result of the structural analysis of the machine is presented, which is performed during the detailed design process. It is also presented how we improve the thermal characteristics of the machine tool by changing the installation position of the actuators.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.47-54
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• 2017

This study examines the implementation of a kinematic machining tool to evaluate the interference and collision phenomenon of 5-axis machining of wing ribs from airplanes, particularly for a large-size model airplane. We develop a machine simulation model of a parallel kinematic machining tool that can operate in a virtual space, which is equivalent to the authentic conditions in the field. The investigation of the simulation function elements indicates the necessity to generate the 6-axis machining, which attaches an angle head to the main axis of the machine. Using an NC program for the wing ribs, we attempt to verify the correspondence and conformity between the machine simulation model and the actual equipment.

• IE interfaces
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• v.12 no.4
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• pp.617-624
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• 1999

In order to maximize an availability of machine and utilization of space, the parallel machines scheduling problem with space limit is frequently discussed in the industrial field. In this paper, we consider a scheduling problem for assembly machine in ship engine assembly shop. This paper considers the parallel machine scheduling problem in which n jobs having different release times, due dates and space limits are to be scheduled on m parallel machines. The objective function is to minimize the sum of earliness and tardiness. To solve this problem, a heuristic is developed. The proposed heuristic is divided into three modules hierarchically: job selection, machine selection and job sequencing, solution improvement. To illustrate its effectiveness, a proposed heuristic is evaluated with a large number of randomly generated test problems based on the field situation. Through the computational experiment, we determine the job selection rule that is suitable to the problem situation considered in this paper and show the effectiveness of our heuristic.

• Journal of Information Processing Systems
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• v.8 no.2
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• pp.301-314
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• 2012

In this paper, two new approaches to align English-Arabic sentences in bilingual parallel corpora based on the Multi-Class Support Vector Machine (MSVM) and the Hidden Markov Model (HMM) classifiers are presented. A feature vector is extracted from the text pair that is under consideration. This vector contains text features such as length, punctuation score, and cognate score values. A set of manually prepared training data was assigned to train the Multi-Class Support Vector Machine and Hidden Markov Model. Another set of data was used for testing. The results of the MSVM and HMM outperform the results of the length based approach. Moreover these new approaches are valid for any language pairs and are quite flexible since the feature vector may contain less, more, or different features, such as a lexical matching feature and Hanzi characters in Japanese-Chinese texts, than the ones used in the current research.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.563-564
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• 2009

• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.35
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• pp.107-114
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• 1995

This paper proposes the Tabu Search algorithm to minimize mean tardiness in the parallel machine scheduling problem. The algorithm reduces the computation time by employing restricted neighborhood and produces an efficient solution in this problem.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.11
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• pp.99-109
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• 2004

This paper proposes precision evaluation method for the positioning error of three-DOF translational parallel mechanism. The proposed method uses conventional CMM as metrology equipment to measure the position of end-effector. In order to obtain accurate measurement data from CMM, the transform relationship between the coordinate system of the parallel mechanism and the CMM coordinate system must be identified. For this purpose, a new coordinate referencing (or coordinate system identification) technique is presented. By using this technique accurate coordinate transformation relationships are efficiently established. According to these coordinate transformation relationships, an equation to calculate error components at any arbitrary position of the end-effector is derived. In addition, mathematical fitting models to represent the position error components in the two-dimensional workspace of the parallel mechanism are also constructed based on response surface methodology. The proposed error evaluation method proves its effectiveness through the experimental results and its application to real three-DOF parallel mechanism.