• Research in Mathematical Education
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• v.9 no.3 s.23
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• pp.187-201
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• 2005

The spreadsheet Microsoft Excel is the most widely used mathematical tool in today's workplace. Moreover, it is also an outstanding means for developing a surprisingly wide range of creative and innovative educational uses within such areas as mathematical modeling, visualization, and instruction. The spreadsheet's format provides us with a tool that closely parallels the way in which we naturally carry out problem solving, while the spreadsheet creation process itself illuminates the underlying mathematical concepts. In addition, the spreadsheet's visual layout allows us to introduce a broad variety of challenging and interesting topics, and to design creative demonstrations through eye-catching animated graphics. The material presented comes from actual classroom mathematics teaching experience in both industrially advanced and developing nations. A series of highly visual interactive illustrations from mathematics, the natural and social sciences, computing, engineering, and the arts provide a number of usable examples. The material discussed is applicable at diverse levels, ranging from schools and universities through adult education and in-service teacher development programs.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.6
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• pp.48-59
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• 1990

A finite element program was developed using line elements for simulating the stretch/draw forming operation of an arbitrarily-shaped plane-strain section. An implicit, incremental, updated Lagrangian formulation is employed, introducing a minimum plastic work path assumption for each time step. Geometric and material nonlinearities are also considered within each time step. The finite element equation is based on the mesh-normal, which compatibly describes arbitrary tool surfaces and FEM meshes without depending on the explicit spatial derivatives of tool surfaces. The membrane approximation is adopted under the plane stress assumption. The sheet material is assumed to obey a rigid-viscoplastic constitutive law. The developed program was tested in the die-tryout of typical automotive inner panels. In order to determine a single friction coefficient and boundary length, FEM results and measurements of thinning for a stretched section of final die were compared. After finding analysis parameters, the sheet forming operations of original and final die designs were simulated. Excellent agreement between measured and computed thickness strains was obtained and the developed program was able to identify die designs which were rejected during die tryout.

• Archives of Reconstructive Microsurgery
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• v.18 no.2
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• pp.75-78
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• 2009

Purpose: Microsurgery is an essential technique in plastic and reconstructive surgery. However, microsurgical suturing and handling of the instrument are difficult for beginners, and who requires a steep learning curve. Therefore, methods for improving the technical skill are needed. The authors describe the value of a small stereoscopic microscope as a training tool. Materials and Methods: A small stereoscopic microscope was used to help improve the microsurgical skill. Monofilament 10-0 Nylon and a surgical rubber globe were used as a suture material and education material, respectively Result: Stereoscopic view of the operation field was obtained and basic microsurgical suture was possible. Conclusion: The stereoscopic microscope is an effective training tool for beginners of microsurgery with benefits in cost and usefulness in small place.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1613-1617
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• 2009

As demand regarding a recent energy-saving rises, the using ratio of the aluminum plate in manufacturing of a railroad vehicle has been increasing. The aluminum structure to be applied to a railroad vehicle is divided to single skin and double skin, and the main aluminum product is mainly Al 6005 extrude and Al 5083 rolled in domestic market. The Al 6005 alloy is applied heat treatment in order to improve the strength of material. Therefore there is the disadvantage that the strength of welding zone decreases compare with base material's if you apply to fusion welding like MIG(metal inert gas) welding. In this paper we tried to apply friction stir welding to solve these problems. In this study we investigated how tensile strength and fatigue strength were changed in case of changing the shoulder diameter of thread tool.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.473-476
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• 2005

Today's manufacturing industry is facing challenges from advanced difficult-to-machine materials (WC-Co alloys, ceramics, and composites), stringent design requirements (high precision, complex shapes, and high surface quality), and machining costs. Advanced materials play an increasingly important role in modem manufacturing industries, especially, in aircraft, automobile, tool, die and mold making industries. The greatly-improved thermal, chemical, and mechanical properties of the material (such as improved strength, heat resistance, wear resistance, and corrosion resistance), while having yielded enormous economic benefits to manufacturing industries through improved product performance and product design, are making traditional machining processes unable to machine them or unable to machine them economically. In this paper, mechanical characteristic evaluation test of fine powder type WC-Co alloy was accomplished to obtain clear data for miniaturized special die parts machining with high reliability and high quality.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.294-298
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• 2000

As the LED or LCD technology has been developed, if we use LED or LCD pannel, more wide color range coluld be obtained as CRT monitor. Specially, full color LED display is developed by high brightness blue LED. It can be applicable to display pannel with a long-life, wide visible angle and high brightness. A display pannel shows the images of CRT monitor performed by the main computer. Graphic application in the main computer is therefore more important in the market. Conventional 3D STUDIO, one of graphic softwares, has difficulties in manipulating and understanding the specific terminology so that one may need more time to learn it. We, therefore, developed graphic application which can recycle the conventional 3D images by creating or editing the image easily.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.206-206
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• 2007

PCB기판 제작에 있어서 미세패턴을 형성하기 위한 차세대 공법으로 imprint공법을 이용하여 PCB기판제작에 대한 내용입니다. imprinting을 하기 위해서 미세때턴이 형성된 Tool-foil을 이용하여 imprinting시 Via hole을 동시 가공을 함으로서, 공정 비용 절감과 공정 프로세스 단축의 효과를 볼수 있다. 하지만 대면적(405*510size) imprint용 N-stamp제작이 쉽지 않으며, Ni-stamp가격 또한 만만치 않으며, 대면적 size일수록 이형처리 또한 쉽지 않다. 이형문제와 Stamp제작 비용을 줄이기 Cu-stamp를 제작 하여, Imprint후 이형처리 하지 않으며, Stamp제작 또한 쉬우며, 가격도 싸기 때문에 그에 따른 기대효과를 간략하게 소개 하고자 한다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.85-91
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• 2013

The machinability of wear-resistible tungsten carbides and the tool wear behavior in machining of V30 and V50 tungsten carbides using PCD (Poly Crystalline Diamond) cutting tool was investigated to understand machining characteristics. This material is one of the difficult-to-cut materials in present, but their usage has been already broadened to every commercial applications such as mining tools, and impact resistant tools etc. Summary of the results are as follows. (1) Tool wear progression of PCD tools in turning of wear-resistible tungsten carbides were observed specially fast in primary cutting distance within 10m. (2) Three components of cutting resistance in this research were different in balance from the ordinary cutting such as that cutting of steel or cast iron. Those were expressed large value by order of thrust force, principal force, feed force. (3) If presume from viewpoint of high efficient cutting within this research, a proper cutting speed was 15m/min and a proper feed rate was 0.1mm/rev. In this case, it was found that the tool life of PCD tool was cutting distance until 230m approximately. (4) In cutting of wear-resistible tungsten carbides such as V30 and V50, it was recognized that the tool wear rate of V30 was very fast as compared with V50. (5) When the depth of cut was 0.1mm, there was no influence of the feed rate on the feed force. And the feed force tended to decrease as the cutting distance was long, because the tool was worn and the tool edge retreated. (6) It was observed that the tungsten carbides were adhered to the flank.

• Transactions of Materials Processing
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• v.31 no.3
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• pp.129-135
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• 2022

The purpose of this study was to quantitatively evaluate the influence of hardness of tool materials on wear resistance in the sheet metal forming process. Punches used in the wear test were made of STD-11 and K340 tool material, and the tempering temperature was set to 530℃ and 500℃, respectively, to control the hardness of the tool materials. The punches mimic the shape of stamping tool of automotive body component to reflect its plastic deformation, and are designed to concentrate wear on the curvature region of punches. Progressive die and coil sheet were used to save time, cost, and raw sheet materials. By quantitatively measuring the wear depth of the punches, the wear behavior and mechanism of the punches were investigated, and characteristics of hardness and wear resistance according to tool materials and tempering temperatures were evaluated. Testing results indicate that the punch made of K340 tool steel with higher hardness had better wear resistance than that of STD-11 tool steel, and the hardness and wear resistance of tool steel were significantly impacted by the tempering temperature.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.34-41
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• 2004

The purpose of this paper is to look at the characteristics of surface finishing which is one of the form accuracies and to obtain the fundamental technical data from the process of machining with diamond tool through experiment and theoretical analysis. The experiments were conducted with domestic made ultra-precision machine and MCD.PCD tool, with aluminum alloyed material and brass being used for the work pieces. The goal of the size accuracy was set to 100nm. The most suitable tool nose radius and machining conditions were selected, and the variations of the surface roughness were observed using SEM method while machining the distance of up to 500km. These data were evaluated and they examined the variation of the machined surfaces while cutting up to 500km of machining distance. At the same time, the state for the wear of diamond tool nose was analyzed and carefully examined through the newest measuring device. Additionally, the characteristics of ultra-precision machining technology were studied through visual analysis.