• Journal of the Korean Society for Precision Engineering
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• v.17 no.11
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• pp.69-74
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• 2000

Roughness of curved surfaces finished with flexible tools depends on the tool/work contact pressure and area. In this study, non-Hertzian closely conforming elastic contact theory is employed to analyze the tool/work contact and to generate a tool path producing a constant pressure at initial contact points. Finishing experiments on curved surfaced are conducted using the tool path. For comparison, curved surface finishing is also performed along the tool path producing a constant tool/work interference depth. It is demonstrated that the tool path of constant contact pressure improves the finished surface roughness.

• 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.

• Journal of Engineering Education Research
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• v.16 no.3
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• pp.42-50
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• 2013

The main purpose of this study was to develop a program outcomes assessment tool using reflection journal. Reflection journal has recently come to gain more attention from school as an alternative assessment tool. Although numerous studies reconfirmed the educational importance and value of reflection journal as an assessment tool, research on the assessment tool of the engineering accreditation, based on education view is scarce. After literature reviews about the case studies on the program outcomes assessment, this study, to analyse the current assessment tools, and then, examined the educational implications of reflection journal as a program outcomes assessment tool. This study suggested the assessment tool using reflection journal for PO6 (teamwork) and PO11 (engineering ethics), one of the most important assessment items in engineering accreditation. In this study, we used the performance criteria, assessment criteria, rubric, and closed the loop to measure the teamwork and engineering ethics. The result of this study is significant in terms of guiding the future evaluation system development for program outcomes.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.3
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• pp.266-270
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• 2013

Automatic tool changer(ATC) is typically provided to a machine tool to improve the efficiency of the machine tool significantly by saving time in moving, switching, installing and storing tools as well as adjusting a calibrating the machine tool. In this study, technical trend of machine tools automatic tool changer are analyzed by patent mapping. And future development direction of automatic tool changer has suggested. The analysis is carried out by using problem solution map for the applied patent during 2000 and 2010 in USA, Japan, Europe and Korea.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.781-785
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• 2005

Cutting forces and tool deflection in end milling are represented as the closed form of tool rotational angle and cutting conditions. The discrete cutting forces caused by tool entry and exit are continued using the Fourier series expansion. Tool deflection is predicted by direct integration of the distributed loads on cutting edges. Cutting conditions, tool geometry, run-outs and the stiffness of tool clamping pan are considered for cutting forces and tool deflection estimation. Compared to numerical methods, the presented method has advantages in short prediction time and the effects of feeding and run-outs on cutting forces and tool deflection can be analyzed quantitatively. This research can be effectively used in real time machining error estimation and cutting condition selection for error minimization since the ferm accuracy is easily predicted by tool deflect ion curve.

• Structural Engineering and Mechanics
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• v.31 no.1
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• pp.57-74
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• 2009

Power signals resulting from spindle and feed motor, present a rich content of physical information, the appropriate analysis of which can lead to the clear identification of the nature of the tool wear. The partial least-squares regression (PLSR) method has been established as the tool wear analysis method for this purpose. Firstly, the results of the application of widely used techniques are given and their limitations of prior methods are delineated. Secondly, the application of PLSR is proposed. The singular value theory is used to noise reduction. According to grey relational degree analysis, sample variable is filtered as part sample variable and all sample variables as independent variables for modelling, and the tool wear is taken as dependent variable, thus PLSR model is built up through adapting to several experimental data of tool wear in different milling process. Finally, the prediction value of tool wear is compare with actual value, in order to test whether the model of the tool wear can adopt to new measuring data on the independent variable. In the new different cutting process, milling tool wear was predicted by the methods of PLSR and MLR (Multivariate Linear Regression) as well as BPNN (BP Neural Network) at the same time. Experimental results show that the methods can meet the needs of the engineering and PLSR is more suitable for monitoring tool wear.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.15-21
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• 2000

This study presents a procedure for analyzing chip-tool friction and shear processes in 3-D cutting with a single point tool. The edge of a single point tool including a circular nose is modified to an equivalent straight edge, thereby reducing the 3-D cutting with a single point tool to the equivalent of oblique cutting. Then, by transforming the conventional coordinate systems and using the measurements of three cutting force components, the force components on the rake face and shear plane of the equivalent oblique cutting system can be obtained. As a result, the chip-tool friction and shear characteristics of 3-D cutting with a single point tool can be assessed.

• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.58-63
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• 1993

The charactistics of AE(Acoustic Emission) signal is related to cutting conditions, tool materials and tool geometry in metal cutting. The tool geometry change which is derived from tool wear affects the source of AE signal in machining process. The relationship between AE signal and tool wear was experimentally investigated. THe value of RMS(Root Mean Sequare) and Amplitude of AE signal were increased in tool wear condition. Also the high value of Count per Hit and Count vs. Frequency was observed in this condtion. As a result, tool wear can be effectively detected by AE signal during cutting operation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.272-276
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• 1993

We made to develop CNC Tool Grinding Machine automating the linear motion of X,Y,Z axis of table, and thetilting and rotation of tool holding vice by using Encorder to increase the efficiency of tool grinding for the Conventional Tool Grinding Machine. We did not consider the part of static, dynamic and thermal behavior that must necessary consider when wedesign, because we used existing Conventional Tool Grinding Machine as it is. We investigated simulation to make existing Conventional Tool Grinding Machine like CNC. We also designed it, and we compared the capability of existing Conventional Tool Grinding and CNC Tool Grinding Machine, and we investigated, too.