• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.3-8
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• 2001

This study is an investigation for the ADS optimum design by using FEA. We write out program which express ADS perfectly and reduce the required time for correcting of model to the minimum in solution and manufacture result. We complete algorithm which can plan optimum forming of model by feedback error information in CAE. Then we correct model by feedback date obtaining in solution process, repeat course following stress solution again and do modeling rachet wheel for optimum forming. That is our aim. In rachet wheel, greatest equivalence stress originates in key groove corner and KS standard is proved the design for security.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.934-937
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• 2001

It is well-known that the micro fabrication technology of micro parts are the high energy beam or silicon-based micro machining method such as LIGA Process, Laser machining, photolithography and etching technology. But, for fabricating complex 3-D structure it is better to use mechanical machining. This machining method by the mechanical machine tool with nanometer accuracy is getting attention in some field-especially micro optics machining such as grating, holographic lens, micro lens array, fresnel lens, encoder disk etc.. In this study, we survey the micro fabrication by mechanical cutting method and set up the mechanical micro machining system. And we carried out micro cutting experiments for micro parts with v-shape groove.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.523-527
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• 2011

Polycarbonate (PC) polymer is an engineering plastic which has large tensile strength and impact resistance and is wildly used as functional parts like micro mold. Direct machining of PC materials produces lots of burrs and rough surface due to large ductility and weak heat resistance and hence it is very difficult to machine PC materials using cutting tool to make micro-parts. In this study, elliptical vibration cutting (EVC) or 2-dimensional vibration cutting was performed to minimize the size of micro V-grooves on PC material. From the experimental results, it was observed that as the cutting depth and pattern size become smaller, the better machining quality was obtained, which is attributed to the positive effect of EVC that is dependent on the ratio of vibration amplitude to cutting depth. As the height of V-groove becomes less than $1.8{\mu}m$, however, the machining quality becomes lower as the pattern size decreases.

• Tribology and Lubricants
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• v.29 no.4
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• pp.248-254
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• 2013

This paper presents a numerical model for investigating the structural dynamic response of an unbalanced rotor system supported on deep groove ball bearings. The aim of this work is to develop a numerical model for investigating the effect of the number of balls on the dynamic characteristics of the rotor ball bearing system. The fourth-order Runge-Kutta numerical integration technique has been applied. The results are presented in the form of time displacement responses and frequency spectra. The analysis demonstrates that the model can be used as a tool for predicting the nonlinear dynamic behavior of the rotor ball bearing system under different operating conditions. Moreover, the study may contribute to a further understanding of the nonlinear dynamics of rotor bearing systems.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.3
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• pp.45-50
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• 2002

This study is an investigation far the Am optimum design using FEA. We write out program which express ADS perfectly and reduce the required time far correcting of model to the minion in solution md manufacture result. We complete algorithm which can plan optimum forming of model by feedback error information in CAE. Then we contract model by feedbback date obtaining in solution process, repeat course following stress solution again iud do modeling rachet wheel for optimum forming. That is our aim. In cachet wheel, greatest equivalence strss originates in key groove comer and KS standard is proved the design far security.

• 연구논문집
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• s.25
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• pp.105-113
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• 1995

Fresnel lenses are developed for flat optics with the optical characteristics close to aspherical lens such as sharp focusing and dispersion instead of spherical or aspherical surface. Usually, these fresnel lenses and diffraction gratings are machined by high-energy beam such as electron beam machining, but recently with the development of ultra precision machine tool and machining technology, 3-dimension micro machining becomes preferable. This study on the micro machining of fresnel lens is carried out to develop the basic technology of ultra precision micro machining. The machined lens mold will be used for the manufacturing of fresnel lens with 120mm focal distance using synthetic resin material with 1.49 refractive index(PMMA), and the shape of lens is 48mm diameter, $300\mum$ pitch and about $5-700\mum$depth of groove in brass.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.265-265
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• 2004

최근 IT산업으로 대표되는 광통신 및 광신호 전달에 이용되는 광 반사경 및 렌즈어레이, 광가이드 판넬(BLU, FLU)등 광부품의 수요가 급증하고 있고, 이의 생산을 위한 다양한 제조공정이 연구 개발되고 있다 근년까지 이러한 마이크로 광부품의 제조방법은 포토리소그래피, 에칭기술을 베이스로 한 MEMS 기술, PDMS를 이용한 복재기술에 크게 의존하고 있다. 기계적 가공법으로는 오래전부터 초정밀 경면 선삭이나 연삭에 의한 마이크로 렌즈와 미세 패턴의 금형가공이 이루어져 왔다.(중략)

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.6
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• pp.68-73
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• 2005

Tire manufactures have dealt with noise problem by varying the pitch of the tread. The various formulas for the variations are generally determined differently, however. Often these variations are based on a combination of trial and error, intuition, and economics. Some manufactures have models and analogs to test tread patterns and their variations. These efforts, however practical, do not determine the best variation beforehand or guarantee the best results. For this reason it was felt that a general mathematical approach fur determining the best variation was needed. Moreover, the method should be completely general, easy to use, and sufficiently accurate. This paper discusses a mathematical method called Mechanical Frequency Modulation(MFM) which meets the above requirements. Thus, MFM pertains to computing an irregular time sequence of events so that the resulting excitation spectrum is shaped to a preferred form. The first part of this paper treats the theoretical basis for computing an optimum variation ; the second part discusses experimental results and simulation program which corroborate the theory.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.117-124
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• 2007

The pressure ripple in most hydraulic systems is the root cause of their noise and vibration. This paper reduced the pressure ripple using side branch hose for an axial piston pump applied to small excavator. First, in calculating open area, a new method using groove area of valve plate is proposed. Simulation model in AMESim environment is developed to verify proposed method, find effective length and diameter of branch hose. Finally, the comparisons with experiment results show that the proposed method is more effective than previous method in reducing the pressure ripple.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.6
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• pp.179-184
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• 1994

In this study a nondimensional parameter, feed/land length(F/L) was introduced, and using this parameter, cutting performance and chip breaking characteristics of the groove and the land angle type chip formers were assessed. Specific cutting energy consumed and shape of broken chip with its breaking cycle time were appraised to find out the ranges of F/L value where efficient cutting and effective chip breaking could be achieved. C type chip was found out to be the most preferable in terms of cutting efficiency.