• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.5
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• pp.73-80
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• 2002

In this study, work materials of the ree form surface shape was machined by ball end mill cutter according to the change of cutting location and depth, and the acquired data of cutting force, tool deflection and shape accuracy were analyzed. Cutting force results were obtained with tool dynamometer and tool deflection values were measured by a couple of eddy-current sensors. Shape accuracy was obtained by roundness tester and surface profile measuring machine. As inclination angle was decreased, cutting force was increased. Cutting force showed large value at $105^{\circ}$ and $150^{\circ}$. Tool deflection was less at down milling than at up milling, decreased at 45$^{\circ}$ and 120$^{\circ}$, and shown large tool deflection at $150^{\circ}$. Roughness values were found to be bad in the inside of surface shape tool deflection. Surface accuracy was obtained better precision in down milling than in up milling.

• Proceedings of the Technology Innovation Conference
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• 1996.12a
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• pp.154-178
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• 1996

This paper applies the technology-gap trade theory to explaining radical changes in the competitive positions of countries in world machine tool markets over the last three decades. It develops the notion that the innovation gaps in machine tools among countries led to the inter-country differences in the competitive performance in the sector as well as in its user sectors. Since competitive advantage largely depends on a capability to improve, create and apply technology to market competition, a higher innovative performance in one country than another is closely related to a higher innovative performance. A higher innovative performance in machine tools is also associated with a higher competitive performance of the large areas of its user sectors, due to sectoral interdependences and externalities generated by machine tool innovations. The results of empirical investigation through a panel data analysis show that the international gaps in machine tool innovations appeared to have a positive significant relationship with the differences in the export performance of both the machine tool sector and its user sector across countries.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.8
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• pp.43-49
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• 2004

The objective of this research is to investigate the effect of clearance angle on cutting performance in high speed end milling operation. The tool geometry parameters have complex relationship with cutting process parameter. In order to explain the effect of clearance angle, 2D turning operation in lathe and end milling operations are performed. Tools with different clearance angles are manufactured. Cutting forces, machining accuracy and tool life are examined according to the change of clearance angle. As clearance angle increases, cutting force decreases and machining accuracy improves. But it has been proved that there exists the optimal clearance angle according to the diameter of end mill for maximum tool life which is measured by frank wear.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.416-421
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• 2004

Off-line feedrate scheduling is presented as the advanced technology to regulate cutting forces at the desired level through change of feedrates. In rough cutting, the feedrate scheduling aims at reducing the machining time, which is the most important factor for better productivity. Thus, the largest force which can avoid breakage of tool shank and tooth is a reference force for feedrate scheduling in rough cutting. In this paper, a calculation method of the reference cutting force for feedrate scheduling is developed. This model calculates rupture plane of tooth using the FEM analysis of a tool and computes the reference force using the transverse rupture strength of a tool. Experiments validate that the presented feedrate scheduling model reduced machining time drastically and regulate cutting forces at the reference cutting force.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.4
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• pp.24-29
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• 2017

This paper provides an experimental analysis on the breakage of the coated tool using the face-milling cutter of the machining center due to changes in the cutting speed and the feed rate. The experimental studies were conducted using STS 304 materials and the damage to the tool was analyzed according to the change in machining time. The experiments confirmed that the cutting speed and feed rate affected the tool damage and the mechanical impact and thermal shock were determined to severely damage the tool. From the production engineering point of view, it has been experimentally investigated that the increased feed rate significantly influences the material removal rate more than the increased cutting speed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.341-342
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• 2006

This study is concerned about the development of tower type automatic tool changer. The tower type automatic tool changer is developed to reduce stand-by time by shortening tool change time. The developed system can store more number of tools in small space. A structural analysis for the machine is carried out to check the machine design using commercial software, CATIA V5. In the result of structural analysis, the safety of the developed system is confirmed.

• Journal of the Ergonomics Society of Korea
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• v.15 no.2
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• pp.177-184
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• 1996

In light-weight hand tools, static posture may result in postural fatigue. Psotural tremor of the upper extremity in a static posture was measured to provide guidelines for hand tool weight. Postural tremor was measured on five levels of tool weitht : no weight, 400g, 800g, 1200g, and 1600g. Three types of camcorder recording postures were selected. For each condition, postural tremor was measured together with ENG of biceps, deltoid and pectoralis major, and Borg's CR-20 ratings of perceved exertion. Results of the experiment are as follows : frequency analysis of tremor revealed increased amplitude of frequency bands of 2-4Hz and 10-14Hz. Postural tremor of the upper extremeity maintained the initial level until fatigue developed. After the development of fatigue, the rate of change of postural tremor significantly increased. Different tool weights and hand postures showed different rates of tremor increase. Time tp fatigue and corresaponding endurance time were positively correlated with Borg's RPE scores.

• Journal of Preventive Medicine and Public Health
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• v.56 no.4
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• pp.384-387
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• 2023

The aim of this study was to present a framework for clinicians to use when discussing electronic cigarette (e-cigarette) use and its association with pre-diabetes. A communication tool was designed using evidence-based strategies from the academic literature. A four-step framework is presented, which includes: step (1) helping patients to understand the association between e-cigarette use and pre-diabetes; step (2) the synergistic health impacts of e-cigarette use and pre-diabetes; step (3) management of diabetes-related lifestyle factors; and step (4) stages of change assessment related to e-cigarette reduction. This communication tool provides support for clinicians to discuss the risk of pre-diabetes associated with e-cigarette use. Moving forward, implementation and evaluation of this model are needed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.11
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• pp.2336-2341
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• 2002

When WC and group IV elements are added to Ti(C,N)-Ni cermet, microstructures of the cermet is changed. The change effects directly on the property of the material. In this study, the amount of WC and group IV elements of Ti(C,N) cermet tool was investigated. The composition of WC was changed from 5 to 20wt% to determine the effect of WC on the cutting performance of cermet tool. The more WC was added, the longer the tool life of the cermet tool was. The cermet with lwt% ZrC and l4wt% WC showed the best cutting performance among the investigated cermet tools. The cutting performance of cermet cutting tools suggests the possibility in interrupted cutting for reliability test experimentation was performed repeatedly with $Ti(C_{0.7},N_{0.3})- l4WC-1ZrC-20Ni$ cermet tool machining SCM440. The flank wear of cermet cutting tool at given time condition is suitable for Normal distribution and Log normal distribution by Chi squared test.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.2
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• pp.38-44
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• 2008

Titanium and its alloys, due to their superior properties of high specific strength and excellent corrosion resistance, are increasingly used in living applications in the 21century. The applications in aerospace and medical industries demand machining process more frequently to obtain a desired product. But unfortunately, this material is one of the most difficult-to-cut. In the turning process of titanium alloys, the key point for successful work is to select proper tool materials and cutting conditions. This study suggests a guidance for selecting the tool materials and the cutting speeds to improve tool life and surface integrity in Ti-6Al-4V titanium turning process. The experiments investigate the change of surface roughnesses, cutting forces and flank wear with various cutting parameters of tool materials, depth of cuts and feeds. As the results, K10 type of insert tip was assured as the best for turning of Ti-6Al-4V titanium alloy.