• Journal of the Korean Society of Manufacturing Process Engineers
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• v.1 no.1
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• pp.123-132
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• 2002

In this study, the static and dynamic characteristics of endmilling process was modelled and the analytic realization of chatter mechanism was discussed. In this regard, We have discussed on the comparative assessment of recursive time series modeling algorithms that can represent the machining process and detect the abnormal machining behaviors in precision endmilling operation. In this study, simulation and experimental work were performed to show the malfunctional behaviors. For this purpose, new recursive least square method (RLSM) were adopted for the on-line system identification and monitoring of a machining process, we can apply these new algorithms in real process for detection of abnormal chatter. Also, The stability lobe of chatter was analysed by varying parameter of cutting dynamices in regenerative chatter mechanics.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.43-48
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• 2001

In this study, the characteristics of the surface around a hole on inlet and outlet of product which are manufactured by face mill or end mill cutting with a hole or a pocket in its surface, are investigated. Furthermore, experiment for optimization of process conditions to minimize the change of characteristics of milling cut surface after a hole cutting operation, is implemented. Applying the results in this study to surface manufacturing of mold products whose surface is uneven or metal products made by diecasting, reducing the number of sequence process to obtain fine surface is expected.

• Korean Journal of Computational Design and Engineering
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• v.4 no.3
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• pp.247-258
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• 1999

With the contemporary CAD/CAM system, where the tool path is generated and verified purely based on the geometric operation, geometric accuracy of the machined surface cannot be guaranteed dut to the cutting mechanics, meaning that the cutting mechanics should be incorporated in some fashion. In this paper, we incorporate the instantaneous cutting force and the tool deflection phenomena in predicting the machined surface for the finish-cut and milling operation. For the given NC dat including cutting conditions, the developed algorithm computes cutting force and deflection amount along the tool trajectory, and outputs the 3D graphic model of the machined surface together with error analysis. The validity and accuracy of the presented method has been tested by the actual cutting experiments. Experimental results and accuracy enhancement method together with implementing architecture of the VMCS (Virtual Machining CAM System) are discussed in the paper.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.6
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• pp.84-91
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• 2003

In metal cutting operation, it is very important that predict cutting force and work surface. Vibration is an unstable cutting phenomenon which is due to the interaction of the dynamics of the chip removal process and the structural dynamics of machine tool. When vibration on, it reduces tool life, results in poor surface roughness and low productivity of the machining process. In this study, the experiments were conducted in machining center without cutting fluid to investigate the phenomenon of vibration. In the experiments, accelerometers were set up at the tail stock and tool holder and signals were picked up. Surface roughness profiles are generated under the ideal condition and the occurrence of vibration based on the surface shaping simulation model.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.184-189
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• 2003

In metal cutting operation, it is very important that predict cutting force and work surface. Vibration is an unstable cutting phenomenon which is due to the interaction of the dynamics of the chip removal process and the structural dynamics of machine tool. when Vibration occurs, it reduces tool life, results in poor surface roughness and low productivity of the machining process. In this study, the experiments were conducted in machining center without cutting fluid to investigated phenomenon of the Vibration. In the experiments, accelerometers were set up at the tail stock and tool holder and the signals were picked up. In this paper, surface roughness profiles will be generated under the ideal condition and the occurrence of the vibration based on the surface shaping simulation model.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.4
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• pp.73-84
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• 1990

A burr has been defined as an undesirable projection of material formed as the result of plastic flow from a cutting or shearing operation. It is Unavoidable in all kinds of machining operation. This paper describe the burr formation mechanism which is based on the behavior of workpiece material during orthogonal machining of the clay on the milling machine. Specially in this report the rollover burr is dealt as a specific case of the chip formation in the final stage of cutting. The negative shear angle is introduced as an important features of burr formation. It is found that the burr formation process is divided into three stage-initiation, development of negative shearing, and formation of the burr with appropriate assumptions. Using above the burr formation mechanism, the size of burr can be estimated by cutting conditions.

• Korean Journal of Computational Design and Engineering
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• v.4 no.4
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• pp.295-311
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• 1999

An increasing attention is paid to STEP-NC, the next generation CNC controller interfacing STEP-compatible data. In this paper, we first propose an Architecture for the STEP-NC (called FBCC: Feature Baled CNC Controller) accepting feature code compatible with STEP-data, and executing NC motion feature by feature while monitoring the execution status. The main thrust of the paper has been to develop an automatic on-line tool path generation and modification scheme for milling operation. The tool path it generated iota each feature by decomposing into a finite number of primitive features. The key function in the new scheme is haw to accommodate unexpected execution results. In our scheme, the too1 path plinker is designed to have a tracing capability iota the tool path execution so that a new path can be generated from the point where the operation is stopped. An illustrative example is included to show the capability of the developed algorithm.

• Microbiology and Biotechnology Letters
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• v.21 no.2
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• pp.157-162
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• 1993

Raw starch can be effectively saccharified in an enzyme reaction system containing sttrition-milling media. In order to develop an effcient attrition-coupled bioreactor(bioattritor), a rotating drum type bioattitor was construced, and its optimal operation conditions and power consumptions were evaluated. The optimal conditions for 3l bioattritor were 4 baffled, baffle size of 1:0.05 (the ratio of drum diameter to baffle), drum rotation speed of 100 rpm, and 1.33g of 3 mm glass bead/g of raw corn starch.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.993-996
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• 2005

High speed machining(HSM) technique is widely used in the appliance, automobile part and mold industries, which has many advantages such as good quality, low cost and rapid machining time. but it also has problems like tool break, smooth tool path, and so on. In particular, small size end mill is easy to break, so it must be changed before interrupting operation. Generally, the tool life of small size end mill is effected by the milling conditions whose evaluated parameters are spindle, feedrate, and width of cut. The experiments are carried out by full factorial design of experiments using and orthogonal array. This paper shows optimal combination and mathematical model for tool life, and the analysis of variance(ANOVA) is employed to analyze the main effects and the interactions of these milling parameters and the second-order polynomial regression model with three independent variables is estimated to predict tool life by multiple regression analysis.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.1596-1602
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• 2006

대부분의 금형 제작에 있어서 face milling은 가공물의 표면을 매끄럽게 하는 가장 중요한 마무리 공정이다. 이 마무리 단계에서 burr의 형성은 가히 탐탁지 않은 현상중의 하나가 된다. 또한, burr는 가공물의 정밀도를 감소시키고 작업자의 안전에 영향을 미치기 때문에 이를 제거하기 위해 후처리(deburring)과정을 야기 시키며, 불필요한 비용의 발생과 작업의 병목현상을 불러오게 된다. 따라서, burr의 생성 원리를 이해하고 burr의 발생을 최소화 할 수 있는 연구가 필요하게 된다. 이를 바탕으로 deburring의 비용을 줄일 수 있는 최적의 가공계획을 수립해야만 제품의 정밀도를 높일 수 있고, 작업 능률과 생산성을 향상시킬 수 있다. 본 논문에서는 지금까지의 연구보다 좀더 현실적으로 접근하기 위하여 피삭재의 형상이 line, arc, circle, spline 등의 여러 가지 형상으로 복합적으로 이루어진 복합형상에 대하여 burr의 발생을 연구하였고 이에 다중가공 경로까지 고려하여 burr의 형성을 예측할 수 있는 알고리즘을 수립하였다. 더 나아가 본 연구의 궁극적 목적인 burr를 최소로 발생시키는 가공경로를 설계할 수 있는 시스템을 개발하고자 한다