• Korean Journal of Computational Design and Engineering
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• v.10 no.6
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• pp.455-464
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• 2005

This paper discusses the methods of computing tool-paths for machining free-form surfaces on 3-axis CNC machines in die and mould making. In computational view this paper describes the characteristics and issues of the geometric information and the shape, which make computing tool-paths difficult. Important points that should be considered in devising a computing method are also discussed. A newly implemented method is explained and compared with an old method for a commercial CAM system. The implemented method is used in a commercial CAM system and the computing time for an example is presented.

• Korean Journal of Computational Design and Engineering
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• v.6 no.3
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• pp.169-173
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• 2001

Presented in this paper is a CPO tool-path linking procedure optimizing technological objectives, such as dealing with islands (positive and negative) and minimizing tool retractions, drilling holes and slotting. Main features of the proposed algorithm are as follows; 1) a data structure, called a 'TPE-net', is devised to provide information on the parent/child relationships among the tool-path-elements, 2) the number of tool retractions is minimized by a 'tool-path-element linking algorithm'fading a tour through the TPE-net, and 3) the number of drilling holes is minimized by making use of the concept of the 'free space'.

• Journal of the Korea Society of Computer and Information
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• v.25 no.5
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• pp.229-241
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• 2020

In this study, we developed a test tool to measure the computational thinking ability of middle school students and investigated their computational thinking power using the tool. The test tool used exploratory factor analysis to examine the computational thinking scales of Korkmaz et al. (2017) and derive suitable factors and questions for middle school students in Korea. The developed test tool was applied to 492 middle school students to analyze differences in computational thinking ability according to gender, grade, programming experience, type of programming language, and interest. According to the study, male Korean middle school students had higher computing power than females. In addition, students who had programming experience or used text-based rather than block-based programming languages demonstrated higher computational thinking. There was no significant difference in the computational thinking of middle school students according to grade, and the level of interest in artificial intelligence only had a slight influence on computational thinking.

• The Journal of Korean Association of Computer Education
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• v.22 no.5
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• pp.67-77
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• 2019

The purpose of this study is to develop and validate a general-purpose evaluation tool and to analyze their applicability in problem solving programming education for college students of teacher training college. For this purpose, we have redefined the area of computational thinking and detail elements from the viewpoint of problem solving programming, and developed general-purpose computational thinking scale to evaluate them. The reliability and validity were analyzed by applying the evaluation tool developed for the actual college students of teacher training college. Through this study, it was confirmed that the a general-purpose evaluation tool developed in this study can be used as a tool to computational thinking assessment and can be generalized.

• Korean Journal of Computational Design and Engineering
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• v.9 no.4
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• pp.286-293
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• 2004

Recently, hot processing using the heat source like laser machining and RFS was developed and spreaded gradually. In order to generate tool-path for the proper hot tool, a new tool-path linking algorithm is needed because tool-path linking algorithm for machining can't be applied. In this paper, zigzag tool-path liking algorithm was proposed to generate tool-path automatically for RFS. The algorithm is composed of three steps: 1) Generating valid tool-path element, 2) Storing tool-path elements and creating sub-groups, 3) linking sub-groups. Using the proposed algorithm, CAD/CAM software for the tool-path generation of hot tool was developed. The proposed algorithm was applied and verified for Venus's face and die of cellular phone case.

• Journal of The Korean Association of Information Education
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• v.20 no.3
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• pp.255-262
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• 2016

In this paper, we proposes a method to effectively evaluate learner competencies of computational thinking. Developed descriptive performance assessment tool is the use of assessment items presented in a creative computing MIT. This tool is selected and modified items through expert delphi technique. The performance assessment tool is composed of four areas that are an experimenting and iterating, testing and debugging, reusing and remixing and abstracting and modularizing. We apply to software classes for the pre-service teachers and conducted this descriptive performance assessment. Applying result of the assessment, the developed assessment tool shows the reliability $Cronbach-{\alpha}$ values higher than 0.6. In addition, the validity of the test results is higher in experts delphi test. Descriptive assessment tool suggested in this study are identified as a useful assessment tool to effectively measure student CT competencies.

• Korean Journal of Computational Design and Engineering
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• v.2 no.1
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• pp.19-27
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• 1997

This paper presents rough cut tool path planning for the fewer-axis machine consisting of a three-axis CNC machine and a rotary indexing table. In the problem dealt with in this paper, the tool orientation is "intermediately" changed, distinguished from the conventional problem where the tool orientation is assumed to be fixed. The developed rough cut path planning algorithm tries to minimize the number of tool orientation (setup) changes together with tool changes and the machining time for the rough cut by the four procedures: a) decomposition of the machining area based on the possibility of tool interference (via convex hull operation), b) determination of the optimal tool size and orientation (via network graph theory and branch-and bound algorithm), c) generation of tool path for the tool and orientation (based on zig-zag pattern), and d) feedrate adjustment to maintain the cutting force at an operation level (based on average cutting force). The developed algorithms are validated via computer simulations, and can be also used in pure fiveaxis machining environment without modification.

• Journal of Computational Design and Engineering
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• v.2 no.4
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• pp.197-205
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• 2015

Bladed disk (BLISK) is a vital part in jet engines with a complicated shape which is exclusively machined on a five-axis machine and requires high accuracy of machining. Poor quality of tool orientation (e.g., false tool positioning and unsmooth tool orientation transition) during the five-axis machining may cause collision and machine vibration, which will debase the machining quality and in the worst case sabotage the BLISK. This paper presents a reference plane based algorithm to generate a set of smoothly aligned tool orientations along a tool path. The proposed method guarantees that no collision would occur anywhere along the tool path, and the overall smoothness is globally optimized. A preliminary simulation verification of the proposed algorithm is conducted on a BLISK model and the tool orientation generated is found to be stable, smooth, and well-formed.

• Korean Journal of Computational Design and Engineering
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• v.16 no.4
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• pp.300-304
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• 2011

This paper proposes an approach to generate tool-path for laser pattern machining. Considering the mechanical structure of a laser pattern machine, it is quite similar to that of a 2D milling machine. Based on the observation, one may try to utilize the tool-path generation methodologies of 2D milling for the laser pattern machining. However, it is not possible to generate tool-path without considering the technological requirements of laser pattern machining which are different from those of 2D milling. In this paper, we identify the technological requirement of laser pattern machining, and propose a proper tool-path generation methodology to satisfy the technological requirements. For the efficient generation of tool-path, this paper proposes a tool-path element computation method, which is based on the concept of a monotone chain.

• Korean Journal of Computational Design and Engineering
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• v.13 no.5
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• pp.382-390
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• 2008

Five-axis machining has been applied to manufacture of turbine blades, impellers, marine propellers. Nowadays it extends to mold & die machining, where more productivity as well as added value is expected. The five-axis machining can be divided into positional and continuous, according to the variableness of tool orientation during material removal process. The positional five-axis machining is commonly applied to the regional machining on a whole part surface in mold manufacturing industry, where the tool orientation for each region (area) should be determined to be feasible, that is, avoiding any interference such as machine tool collision, etc. Therefore it is required for a CAM programmer to decide a feasible tool orientation in generating tool-paths on a designated area, because it is a very tedious job to obtain such information by utilizing a commercial CAM system. The developed system generates feasibility data on tool orientation and machining region, which facilitates the CAM programmer's decision on a feasible tool orientation.