• Korean Journal of Computational Design and Engineering
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• v.20 no.3
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• pp.312-319
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• 2015

The grinding and furbishing process as the finishing process for molds include the works such as the grinding, buffing, lapping and polishing among others. A finishing tool unit is applied to this finishing process for the burr, lapping, polishing and others of molds. A finishing tool unit can carry out the flexible machining, depending on the machining allowance for objects to be cut on the basis of the instrumental driving mechanism which enables the up, down, left and right floating, which is applied in link with the dedicated cutters and robot machining systems. This study selected the shape to increase the rotatory force of an impeller when air is discharged during the driving of a finishing tool unit, and reflected it to the impeller designing. In addition, the study analyzed each flow velocity and pressure distribution per air pressurization value and finally analyzed the rotating torque to suggest the optimal conditions in designing impellers.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.48-53
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• 2005

The world, coming into the 21st century, is preparing a new revolution called a knowledge-based society after the industrial society. The interest of the world is concentrated on information technology, nano-technology and biotechnology. In particular, the nano-technology of which study was originally started from an alternative for overcoming semiconductor micro-technology. It can be applied to most industry subject such as electronics, information and communication, machinery, chemistry, bioengineering, energy, etc. They are emerging into the technology that can change civilization of human beings. Specially, ultra precision machining is quickly applied to nano-technology in the field of machinery. Lately, with rapid development of electronics industry and optic industry, there are needs for super precision finishing of various core parts required in such related apparatuses. This paper handles stability of a super precision micro cutting machine that is a core unit of such a super precision finisher, and analyzes the results depending on the hinge type and material change, using FEM analysis. By reviewing the stability, it is possible to achieve the effect of basic data collection for unit control and to reduce trials and errors in unit design and manufacturing.

• The Mathematical Education
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• v.48 no.1
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• pp.21-32
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• 2009

The purpose of this study is to diagnose the current states and the problems of student assessment of Elementary School Mathematics. For that purpose, this study conducted a survey and had the individual interviews. The surrey items consisted of the six main parts: questions about the development of assessment tools, the method to assess, the grading, the special supplementary courses, the opening of learning effect, and the follow-up guidances. The results of this study are as the follow First, elementary teachers depended heavily on internet sites for developing assessment problems. Second, elementary teachers made use of a performance assessment, a unit assessment, and a term examination at ordinary times. Third, unit assessment was largely referred for grading by elementary teachers. Fourth, in selecting the students for the special supplementary courses, both criterion-referenced assessment and norm-referenced assessment were considered. After finishing the special supplementary courses, additional tests were usually taken. Fifth, elementary teachers took a negative attitude in opening of learning effect. specialty opening of test paper to parents of students was done under 30%. Sixth, fellow-up guidances were the most through the classroom guidances. but consulting with parents of students was not frequently conducted by teachers.

• Tunnel and Underground Space
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• v.8 no.4
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• pp.332-341
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• 1998

Conventional polishing of stone panel edges has been done by hand. While this has changed somewhat with the advent of automatic machines, it is still very much a hand finishing technology. For the development of edge shape milling tool, the primary test on characteristics of edge shape milling tool was carried out. This paper presents the results of tests focused upon the milling capability that was varied by the variables of operation parameters. Author tried to confirm the effect of six operation parameters of equipment such as rotation speed, advance speed, applied load, water flow rate and rotational direction. The result from test was described in term of shape milling capability that was defined as cutting volume of rock by unit weight of tool wear. The variance of the results could indicate the optimum level of each operating parameters. The test was also carried out to determine the abrasion resistance varied according to the abrasive flow rate. The abrasion resistance was increased with the abrasive flow rate, but over some rate it was not changed.