• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1593-1594
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• 2013

• Journal of the Korean Society for Precision Engineering
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• v.28 no.11
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• pp.1279-1287
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• 2011

Weather strip is a functional component of a car body and doors for leaking protection, isolating outside noise and vibration reduction. Insert metal inserted to the weather strip plays a key role to keep the shape of the weather strip and increase its strength. Insert metal is mainly produced by a press process, which has low productivity and 40% material loss due to the scraps. To solve the problems, a high-speed rolling process for manufacturing the insert metal of weather strip is being attempted. In this study, the insert metal is manufactured by a high-speed rolling process, and its process variables: reduction, relative velocity of rollers and the number of passes, are optimized by using the FEA and the actual tests. The prototype was manufactured by the optimal process.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.9
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• pp.1011-1017
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• 2011

Servo control loops are a core part in the control architecture of machine tools. Servo control loops manage acceleration, velocity and position of all the axes in a machine tool based on commands. The performance of servo control loops sets the basis for quality of production paris and cycle time reduction. First, this paper presents a general control architecture of machine tools and several control schemes in literature, which can be applicable to machine tools control; including Zero Phase Error Tracking Control (ZPETC) and Cross Coupling Control (CCC). After that, modem control strategies to mitigate the problem of high speed machining are reviewed. In high speed machining, high accelerations excite the machine structure up to high frequencies, thereby exciting the structure's modes of vibration. These structural vibrations need to be damped if accurate positioning or trajectory following is required. Input shaping is an attractive option in dealing with structural vibrations. The advantages and drawbacks of using input shaping technique for machine tools are discussed in detail.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.185-189
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• 2009

It is very important to control the vibration transmitted from external utilities and the transient response due to the internal sources for the precision equipment, which is very sensitive to the vibration environment. The anti-vibration tables that use air springs have been widely used due to their excellent isolation performance, but the systems with high flexibility have the critical problem of large transient response by the impulsive force of the moving mass in operation of the equipment. In this paper, the hybrid vibration control system is proposed, which is combined the air springs with the semi-active MR dampers in order to satisfy the performances of isolation and vibration reduction simutaneously.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.9
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• pp.687-694
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• 2014

The mount suppliers are providing limited information on the dynamic characteristics of the mounts to some designers and some manufacturers of the high-precision machines. In this technical study, the experimental review was carried out about dynamic characteristics of five kinds of commercial passive mounts sold in the market. The dynamic characteristics, natural frequency and damping ratio, extracted from experimental tests were compared to the materials supplied by mount makers. In order to predict the performance of the high-precision machines with mounts, exact values of the dynamic characteristics of mounts should be used in the stage of numerical analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.808-812
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• 1996

Reduction gear with internal gear pair need functions such as compact size, high reduction ratios, high transmission efficiency, and low noise. Feasible design region of the internal gear pair with a small tooth difference is extremely limited because the internal gear pair is subject to interference in meshing and cutting. Single-objective optimal design can not simulataneously satisfy the manifold requirements of the internal gear pair and can not determine the economical specification of a pinion cutter. Multi-objective optimal design which include the specification of the pinion cutter in design variables is developed, considering the manufacturing error of an internalgear pair and the re-sharpening of the pinion cutter.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.9
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• pp.1094-1102
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• 2011

Recent trends for the miniaturization and weight reduction of portable electronic parts is the use of subminiature components. Assembly of the miniaturized components requires subminiature screws of which pitch sizes are in a micrometer scale. To produce such a subminiature screw with high precision threads, not only a precision forming technology but also high-precision measurement technique is required. In the present work, a vision inspection system is developed to measure the thread profile of a subminiature screw. Optical simulation based on a ray tracing method is used to design and analyze the optical system of the vision inspection apparatus. Through this simulation, optical performance of the developed vision inspection system is optimized. The image processing algorithm for the precision screw inspection is also discussed.

• Journal of Power System Engineering
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• v.15 no.5
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• pp.61-66
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• 2011

Recently, the speed reducer which is applied to robot has conducted a steady development on developments in the field of robotics. Among them, Harmonic drive is a high-stiffness, precision-controlled speed reducer and has high precision, compact, light in weight and high-reduction-ratio characteristics. The feature of flexspline of Harmonic Drive are two types. One is Cup type, the other is Silk Hat type. Silk Hat type is used in case of lighter and more compact in spatial because Silk Hat Type is hollow. According to the shape of silk hat, diaphragm is fractured because stress is concentrated. In this paper, the various shapes of silk hat are suggested to improve the durability of silk hat. And in the case of each shape, a study on stress and deformation using the FEM tool was carried out on flexspline.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.4
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• pp.446-451
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• 2011

Recent trends for the miniaturization and weight reduction of portable electronic parts have driven uses of subminiature components. Assembly of the miniaturized components requires subminiature screws of which pitch sizes are micrometer scale. To produce such subminiature screws with high precision threads, not only a precision forming technology but also a high-precision measurement technology is required. The present study covers the development of a vision inspection system for precision screws for the automatic measurement of subminiature screws with high speed and reliability. In this study, the feeding unit that transfers the subminiature screws to the inspection unit is investigated through finite element(FE) analysis. The vibration characteristics of the feeding unit are predicted through FE analyses, from which we can determine whether the subminiature screw can be stably fed into the inspection unit or not. The effects of several design parameters on the vibration characteristics are also discussed.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.9
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• pp.765-771
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• 2014

During the acceptance test of KTX, unexpectedly great lateral vibration in 14th~16th train at 150km/h~200km/h was appeared on a straight line in the winter season. Generally, stiffness of secondary suspension in KTX vehicle is one of the most sensitive components on air temperature. So, we examined that the secondary suspension to be mounted heating system was able to reduce the lateral vibration in the tail car of KTX. Also, we verified that lateral vibration from test results on KTX train with wheel conicity 1/20 disappeared. In this paper, we analysis effective reduction methods and the cause of the lateral vibration using model of KTX train and compare with the test results. The analysis results agree well with test ones. From mode analysis result, lateral vibration is occurred at natural frequency range 0.5~0.6Hz with a negative damping value and its natural frequency disappear gradually according to increasing of wheel concinicy.