• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.10a
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• pp.58-63
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• 1996

A study is drawn up its result's tables and graphs by measuring tools(outside micrometer cylinder gauge and dial caliper gauge) on the difference of diameter volumes from before-discharge and after-discharge under 52 Kind's experimental condition by cupper and graphite electrode of CNC EDM. The EDM is attached with A.V.R. and memory scope for keep up accuracy and the fixed table of work piece is used in order to eliminate the noise by the internal resistance of it and forcing to eradicate the discharge liquid. It is analyzed cutting conditions to compare its wave value and pulse time.(Ton Toff) through voltage and current for decreasing working error.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.704-707
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• 2000

In this experimental study, noise level measurements were conducted on physical LBB(Linear Ball Bush) samples in a semi-anechoic chamber. Evaluation of the measured data demonstrates that LBB's noise level is proportional to the logarithmic of its speed multiplied by the ball diameter. Furthermore details of implementations and process for measuring noise level and operating speed of LBB are also presented.

• East Asian mathematical journal
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• v.26 no.2
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• pp.281-299
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• 2010

In this study we develop mathematical tools for measuring the Geumgang Ratio and we call them Geumgang Ratio Calipers. Also we show a teaching method for ratio through experimental mathematics. With Geumgang Ratio Calipers students measure the Geumgang Ratio in their bodies, materials for everyday life and the Sukgulam. Through this activity, students obtained an interest in mathematics and gained a positive attitude for mathematics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.254-259
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• 1994

Recently, the precision ball screw becomes the essence of the high-precision industries and is playing a key role in the positioning devices. The standard and definition of pitch error in a precision ball screw is specified by KS, JIS or ISO. However, the method of measuring the pitch error is not concrete. In this study. laser measurement system(LMS) with a laser position transducer and a machine-tools is developed. In order to verify the stability of the LMS, several experiments with the standard ball screw is performed.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.12-16
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• 2002

This paper deals with the measurement of machine parameters of inverter-fed induction motors for an accurate torque control applications such as machine tools and tension control machines. After discussing nonlinearities of both inverter and motor, this paper suggests appropriate compensation and measurement methods. The experimental results show the validity of the proposed method in the operating conditions.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.4
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• pp.295-301
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• 2016

The out-of-squareness is one of the error sources that affect the positioning accuracy of machine tools and coordinate measuring machines. Laser interferometer is widely used to measure the position and angular errors, and can measure the squareness using an optical square. However, the squareness measurement using the laser interferometer is difficult, as compared to other errors due to complicated optics setup and Abbe's error occurrence. The effect of out-of-squareness mainly appears at the face-diagonal of the movable plane. The diagonal displacements are also affected by the position dependent geometric errors. In this study, the squareness estimation techniques via diagonal displacement measurement using the laser interferometer without an optical square were proposed. For accurate estimation and measurement time reduction, the errors selected from proposed discriminant were measured. Discrepancy between the proposed technique with the laser interferometer (with an optical square) result was $0.6{\mu}rad$.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2021_2022
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• 2009

Partial discharges(PD) is a important factor to evaluate the insulation state in high voltage electric machinery. However, measuring PD under the circumstances of power plant is occasionally impossible due to the relatively high magnitude of noise which is emanated from the operating machinery. In some case, the instrument measuring PD can not even perform a calibration that initializes tools and enhance the accuracy. This paper presents that we devised a noise reduction method and demonstrated the usefulness in acquiring reliable PD signals. We attached a series of filter and transformer at the input of power source of the instruments which refrains high noise signals from incoming to the instruments. We experimented the efficiency of noise reduction applying the device into the Dangjin Power Plant and Factory. As a result of testing with the filter and transformer, we can easily calibrate the PD signal compared to the case without the device. Additionally, we can detect the small PD signal which was unperceived with a normal device.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1862-1870
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• 1997

A fast and precise technique to measure 3-dimensional coordinates of an object is proposed. It is essential to take the 3-dimensional measurements of the object in design and inspection. Using this developed system a surface model of a complex shape can be constructed. 3-dimensional world coordinates are projected onto a camera plane by the perspective transformation, which plays an important role in this measurement system. According to the shape of the object two measuring methods are proposed. One is rotation of an object and the other is translation of measuring unit. Measuring speed depending on image processing time is obtained as 200 points per second. Measurement resolution i sexperimented by two parameters among others; the angle between the laser beam plane and the camera, and the distance between the camera and the object. As a result of these experiments, it was found that measurement resolution ranges from 0.3mm to 1.0mm. This constructed surface model could be used in manufacturing tools such as rapid prototyping machine.

• Journal of Environmental Health Sciences
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• v.32 no.2 s.89
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• pp.103-110
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• 2006

The present study is designed to analyze reliability and validity of the instruments used to measure job stress of radiological technologists mainly by means of the questionnaires from 'Korean edition of NIOSH check list'. The subjects of this study are 890 radiological technologists active at 44 general hospitals in 16 provinces and cities across the country. The item-total reliability revealed that 10 factors in 6 are the major causes of stress in job life of radiological technologists. The measuring instrument proved to be valid with reliability coefficient of internal consistency by factors being more than 0.7. The factors found to be applicable herewith include limit and authority of job (0.73), cohesion within departments (0.86), resources control (0.81), mental requirements (0.85), job load (0.82), and job stability (0.72). When job autonomy item of causes are modified for proper use to radiological technologists, the measuring instruments are expected to show high reliability. It seems, however, necessary to develop a measuring instrument to analyze and use the validity of related measuring instruments since the reliability here was rated low, with statistical coefficients lower than 0.7 in such factors as job management (0.57), conflicts within departments (-1.13), sense of responsibility for patients (0.66) and usage of education (0.26). As this study was intended to examine reliability and validity of the concepts related to measurement of job stress on the part of radiological technologists, it nay not be proper to apply the results of this study to general use, but is advised to utilize them as basis for developing instruments to verify reliability and validity by comparing with and analyzing other measuring instruments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.195-201
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• 2012

According to many customers' requests, optical measurement module (OMM) applications using automatic measuring devices to measure the machined part rapidly on a machine tool have increased steeply. Touch trigger probes are being used for job setup and feature inspection as automatic measuring devices, and this makes quality checking and machining compensation possible. Therefore, in this study, the use of touch trigger probes for accurate measurement of the machined part has been studied and a macro program for a hole measuring cycle has been developed. This hole is the most common feature to be measured, but conventional methods are still not free from measuring error. In addition, the eccentricity change of the least square circle was simulated according to the roundness error in a hole measurement. To evaluate the reliability of this study, the developed hole-measuring program was executed to measure the hole plate on the machine and verify the roundness error in the eccentricity simulation result.