• 한국생산제조학회지
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• 제20권1호
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• pp.101-107
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• 2011

Analytical solution of micro-scale milling process is presented in order to suggest available machining conditions. The size effect should be considered to determine cutting characteristics in micro-scale cutting. The feed per tooth is the most dominant cutting parameter related to the size effect in micro-scale milling process. In order to determine the feed per tooth at which chips can be formed, the finite element method is used. The finite element method is employed by utilizing the Johnson-Cook (JC) model as a constitutive model of work material flow stress. Machining experiments are performed to validate the simulation results by using a micro-machining stage. The validation is conducted by observing cutting force signals from a cutting tool and the conditions of the machined surface of the workpiece.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.912-916
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• 2000

The term ‘High Speed Machining’has been used for many years to describe end milling with small diameter tools at high rotational speeds, typically 10,000 - 100,000 rpm. The process was applied in the aerospace industry fur the machining of light alloys, notably aluminium. In recent you, however, the mold and die industry has begun to use the technology for the production of components, including those manufactured from hardened tool steels. And the end mill is an important tool in the milling process. A typical examples for the end mill is the milling of pocket and slot in which a lot of material is removed from the workpiece. Therefore the proper selection of cutting parameter fur end milling is one of the important factors affecting the cutting cost. The one of the advantages of HSM is cutting thin-walled part of light alloy like Al(thinkness about 0.1mm). In this paper, firstly, we study characteristics of HSM, and then, we choose the optimal parameters(cutting forces) to cut thin-walled Al part by experiment.

• 한국식품조리과학회지
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• 제3권1호
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• pp.64-70
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• 1987

배추의 성분조성 및 조직감의 변화에 대한 염장효과에 대하여 연구하였다. 최적 염장조건을 알아보았으며 원료배추 및 염장배추의 dietary fiber 성분조성 무기질 함량 및 수분함량을 측정하였다. 배추의 조직감은 Rheometer에 의한 cutting test에 의하였으며 아삭아삭한 성질 및 씹힘성은 관능검사에 의해 평가되었다. 배추절임을 위한 최적조건은 절임농도가 20%, 절임시간은 6시간이었다. 배추를 20% NaCl용액에서 한달간 염장에 의한 성분변화에 있어서 HW-P는 43.6%에서 59.5%로 증가하였으며 HM-P는 35.9%에서 29.5%로 감소하였다(P<0.05). 그러나 전체 펙틴함량은 거의 변화하지 않았다. 셀룰로오즈, 헤미셀룰로오즈의 함량은 증가하였으나 리그린 함량은 감소하였는데 유의적인 차이는 없었다. Na함량은 현저히 증가하였으나 Ca, Mg, 및 K 함량은 감소하였다. 또한 수분함량은 91%에서 79%로 감소하였다(p<0.05). 배추를 20% NaCl용액에서 한달간 염장에 의한 조직감의 변화에 있어서 최대절단력 및 절단면적은 각각 5배 및 2.5배로 증가하였으며 관능검사 결과 씹힘성은 높아졌으나 아삭아삭한 성질은 낮아졌다(P<0.05). Rheometer에 의한 조직감 parameter와 높은 상관관계를 나타내었다. 이상의 결과로부터 배추를 20% NaCl 용액에서 한달간 염장과정 중 조직감의 변화는 펙틴질 함량, 수분함량 및 무기질 함량의 변화와 관련이 있으나 셀룰로오즈, 헤미셀룰로오즈 및 리그린 함량과는 비교적 관련이 없는 것으로 나타났다. 또한 cutting test에 의한 최대 절단력이 배추의 조직감을 표현하는 좋은 방법이라고 생각되어진다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 Handout for 2000 Inter. Machine Tool Technical Seminar
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• pp.109-115
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• 2000

The spindle unit is core parts in high precision machine tools. Diverse static, dynamic and thermal charateristics of spindle unit are needed for special purpose of machine tools. Compromise between those charateristics will be done in concept design phase. High static stiffness at spindle nose may be very important performance for heavy cutting work. High dynamic stiffness is also useful to high precision and high speed machine tools. Improvement of thermal charateristics in spindle lead to high reliability of positioning accuracy. For high speed spindle structure, the design parameter such as, bearing span, diameter, bearing type and arrangement, preload, cooling and lubrication method should be in harmony.

• 한국정밀공학회지
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• 제14권11호
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• pp.93-101
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• 1997

Ever since the nonlinearity of machine tool dynamics was established, researchers attempted to make use of this fact to devise better monitoring, diagnostics and control system, which were hitherto based on linear models. Theory of chaos which explains many nonlinear phenomena comes handy for furthering the analysis using nonlinear model. In this study, measuring system will be constructed using multi-sensor (Tool Dynamometer, Acoustic Emission) in end milling process. Then, it will be verified that cutting force is low-dimensional chaos by calculating Lyapunov exponents. Fractal dimension, embedding dimension. And it will be investigated that the relation between characteristic parameter calculated from sensor signal and tool wear.

• 한국정밀공학회지
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• 제20권2호
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• pp.218-225
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• 2003

The general dicing process cuts a semiconductor wafer to lengthwise and crosswise direction by using a rotating circular diamond blade. However, inferior goods may be made under the influence of several parameters in dicing process such as blade, wafer, cutting water and cutting conditions. Moreover we can not apply this dicing method to a GaN wafer, because the GaN wafer is harder than other wafers such as SiO$_2$, GaAs, GaAsP, and AlGaAs. In order to overcome this problem, development of a new dicing process and determination of dicing parameters are necessary. This paper describes determination of several parameters - scribing depth, scribing force, scriber inclined angle, scribing speed, and factor for scriber replacement - for a new dicing machine using a scriber.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.164-167
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• 2002

The general dicing process cuts a semiconductor wafer to lengthwise and crosswise direction by using a rotating circular diamond blade. But inferior goods are made under the influence of several parameters in dicing process such as blade, wafer, cutting water and cutting conditions. Moreover we can not applicable this dicing method to GaN wafer, because the GaN wafer is harder than the other wafer such as SiO$_2$, GaAs, CaAsP, and AlCaAs. In order to overcome this problem, development of a new dicing process and determination of dicing parameters are necessary. This paper describes determination of several parameters - scribing depth, scribing force, scriber inclined angle, scribing speed, and factor for scriber replacement - for a new dicing machine using scriber.

• 대한기계학회논문집A
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• 제21권6호
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• pp.988-994
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• 1997

The demands for robotic and automatic system are continually increasing in manufacturing fields. There have been many studies to monitor and predict the system, but they have mainly focused upon measuring cutting force, and current of motor spindle, and upon using acoustic sensor, etc. In this study, digital image of time series sequence was acquired by taking advantage of optical technique. Mean square error was obtained from it and was available for useful observation data. The parameter was estimated using PAA(parameter adaptation algorithm) from observation data. AR(auto regressive) model was selected for system model and fifth order was decided according to parameter estimation. Uncorrelation test was also carried out to verify convergence of parameter. Through the proceedings, it was found that there was a system stability.

• 한국정밀공학회지
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• 제13권10호
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• pp.154-160
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• 1996

The control of diamond turning is usually achieved through a laser-interferometer feedback of slide position. The limitation of this control scheme is that the feedback signal does not account for additional dynamics of the tool post and the material removal process. If the tool post is rigid and the material removal process is relatively static, then such a non-collocated position feedback control scheme may surfice. However, as the accuracy requirement gets tighter and desired surface cnotours become more complex, the need for a direct tool-tip sensing becomes inevitable. The physical constraints of the machining process prohibit any reasonable implementation of a tool-tip motion measurement. It is proposed that the measured force normal to the face of the workpiece can be filtered through an appropriate admittance transfer function to result in the estimated dapth of cut. This can be compared to the desired depth of cut to generate the adjustment control action in additn to position feedback control. In this work, the design methodology on the admittance model-based control with a conventional controller is presented. The recursive least-squares algorithm with forgetting factor is proposed to identify the parameters and update the cutting process in real time. The normal cutting forces are measured to identify the cutting dynamics in the real diamond turning process using the precision dynamoneter. Based on the parameter estimation of cutting dynamics and the admitance model-based nanodynamic control scheme, simulation results are shown.

• 한국식품과학회지
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• 제54권2호
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• pp.247-250
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• 2022

노화 등으로 인한 식빵의 굳기(toughness) 정도를 측정하고자 Miller/Hoseney Toughness 장치를 이용하여 여러 측정조건(이동속도 및 침투율 변화)에서 절단력 최대값을 측정하여 분석하였다. 식빵 겉껍질에서는 이동속도가 증가함에 따라 절단력 최대값이 유의적으로 증가하였으며, 시료들 사이에서의 유의차는 일부 측정조건에서 다르게 나타났다. 식빵 내부에서의 측정값은 동일 침투율에서는 이동속도가 증가함에 따라 대부분의 시료에서 절단력 최대값이 유의적으로 증가하였으며, 시료들 사이에서의 유의차는 침투율에 상관없이 이동속도가 달라져도 변화하지 않았다. 결론적으로 본 실험 방법으로 식빵 내부의 굳기를 측정할 경우 측정조건변화에 의해 절단력 최대값은 달라지나, 시료간 유의차는 변화하지 않아, 시료간 유의차를 판단하는 경우 본 실험 범위내에서 매우 편리하고 신뢰도가 높은 실험으로 사료된다.