• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.99-106
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• 2002

This paper proposes an error compensation method that improves accuracy with geometry information of injection molding parts. Geometric information can give an improved accuracy in reverse engineering. Measuring data can not lead to get accurate geometric model, including errors of physical parts and measuring machines. Measuring data include errors which can be classified into two types. One is molding error in product, the other is measuring error. Measuring error includes optical error of laser scanner, deformation by probe forces of CMM and machine error. It is important to compensate these in reverse engineering. Least square method (LSM) provides the cloud data with a geometry compensation, improving accuracy of geometry. Also, the functional shape of a part and design concept can be reconstructed by error compensation using geometry information.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.3
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• pp.223-231
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• 2005

When test tubes for PCM with melting point lower than a room temperature are installed vertically as the T-history method proposes, there exists a temperature distribution in the longitudinal direction by natural convection, which lowers the precision of measured heat-of-fusion. The purpose of the present work is to improve the precision by arranging the test tubes horizontally, while maintaining the simplicity and convenience. Assuming that the amount of heat transfer is very small through the vapor space formed in the upper part of the tubes by volumetric change, the obtained value by the T-history method using the latent heat period bounded by two inflection points is in good agreement with that of the literature. Also, the scattering of measured values by the proposed method decreases markedly compared to that of vertical positioning.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.45-45
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• 2010

반도체 및 디스플레이 산업에 사용되는 진공펌프의 효율이 증대됨에 따른 성능 평가 기술의 향상 과 미세 유량을 조절 및 측정할 수 있는 시스템의 개발이 요구되고 있다. 유량 시스템 중 소닉노즐은 기체 유량 측정 표준기로 사용되고 있다. 또한 유량 측정에 있어서 사용상의 편리성, 이동성, 재현성 등 여러 가지의 장점을 가지고 있어 산업 현장에서 많이 사용되고 있다. 본 연구는 소닉노즐을 넓은 유량 범위에서 사용할 수 있도록 소닉노즐의 유출계수 교정을 목적으로 한다. ISO 9300에서 제시한 사양에 맞추어 목 직경 0.03 mm와 0.2 mm 그리고 1.6 mm의 소닉노즐을 제작하였다. 한국표준과학연구원에서 진공용 유량측정 장치로 개발된 정적형 유량계를 이용하여 제작된 3 종의 소닉노즐 유출계수를 확장불확도 3% 이내로 교정하였다. 교정된 소닉노즐의 유량 측정범위는 약 0.6~90, 000 cc/min 범위를 갖는 것으로 나타났으며, 사용유동 조건에 해당되는 레이놀드 수(Reynolds number) 범위는 26~75, 700 으로 확인되었다. 이러한 결과는 교정된 소닉노즐을 이용하여 진공공정에서 필요한 극 미세 유량의 정밀측정을 가능하게한 새로운 연구결과로 판단된다. 교정된 소닉노즐을 이용하여 진공펌프의 배기속도 측정결과는 기 구축된 정적법을 이용한 배기속도 측정결과와 3% 이내의 오차범위내로 매우 잘 일치함을 보였다. 교정된 소닉노즐은 향후 반도체 및 디스플레이 공정에 사용되는 다양한 진공펌프들의 배기속도를 현장에서 간단하게 평가할 수 있는 '현장 성능평가 장치'에 활용할 예정이며, 현재 공정현장에서 배기속도 측정에 널리 사용 중인 MFC를 대체할 수 있을 것으로 예상된다.

• Korean Journal of Optics and Photonics
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• v.8 no.4
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• pp.333-339
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• 1997

We fabricated a sensor head which consists of spliced different-diameter fiber gratings for discrimination between strain and temperature. Because the fibers were drawn from the same preform, their temperature characteristics were the same but not for strain sensitivities which are inversely proportional to fibers cross-sectional areas. In measurement range of 0-1500$\mu$strain and 20-10$0^{\circ}C$, we could obtain, by using the matrix calculation, the unknown physical quantities within 10% of calculation error compared with the micrometer and thermocouple values. To improve the strain measurement accuracy, we suggest a new, novel method which deploys an unbalanced fiber Mach-Zehnder interferometer. This new signal processing technique converts the strain information to interference signal amplitude variation, temperature-independently. we obtained measurement accuracy nearly 80 times better than that obtainable with the conventional optical spectrum analyzer usage.

• The Transactions of the Korea Information Processing Society
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• v.4 no.6
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• pp.1508-1518
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• 1997

For the effective development of high qualitative software, it is important to measure the "design quality" through the "process of design" which is the upper phase of software development. And based on it, to improve the "design quality" is also important. But, up to now, most of the researches have been in connection with the quality characteristics, and quality sub-characteristics that can be measured and evaluated by users, but the researches about the internal characteristics and metrics that can be measured and evaluated by developer in the process of the development have not been through going enough. Accordingly, the purpose of this research is to point out the problems included in the internal characteristics of the solution of these problems. Omissions and duplications of the internal characteristics can be prevented by arranging than newly according to the model suggestion. Furthermore, it is confirmed that developers can get the efficiency of measurement by metrics, and also can get good improvement effect of metrics measurement accuracy through the concrete application test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.2
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• pp.175-181
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• 2011

We propose a novel algorithm for measuring the radius of tubes. This proposed algorithm is capable of effectively removing added noise and measuring the radius of tubes within allowable precision. The noise is removed by using a candidate true center that minimizes the standard deviation with respect to the radius. Further, the disconnection in data points resulting from noise removal is solved by using a connection algorithm. The final step of the process is repeated until the value of the standard deviation decreases to a small predefined value. Experiments were performed using circle geometries with added noise and a real tube with complex noise and that is used in the braking units of automobiles. It was concluded that the measurement carried out using the algorithm was accurate within 1.4%, even with 15% added noise.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2369-2378
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• 2009

In this paper, we implement measurement functionality for performance measurement of the GSM (Global System for Mobile Communication) terminal by using software. Generally speaking, the receiving algorithms in normal modems cannot be used directly to the measurement system due to the lack of the algorithm accuracy. In this paper, we propose the new receiver algorithm for precise GSM signal measurements. In the receiving algorithm, 2-stage (coarse stage, fine stage) parameters estimation (symbol-timing, frequency offset, carrier phase) scheme is used. To improve the estimation accuracy, we increase the number of the received signal samples by interpolation. The proposed GSM signal measurement algorithm can be used for verifying the hardware measurement system. In addition, the proposed algorithm can be used for the commercial system through code execution speed optimization.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.2
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• pp.123-128
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• 2014

This paper presents the study about MGV(Magnetic guidance vehicle) with up-and-down rotating type differential drive unit. Previous MGV needs the landmarks to get the driving information and additional sensor to recognize the landmarks except for localization sensor. Previous MGV requires at least 2 drive units when common fixed differential drive unit is used because it occurs the problems with driving control and localization error from imbalance of the MGV's weight. To solve such problems, we propose the MGV using up-and-down rotating type differential drive unit. Proposed MGV recognizes the driving information from the pattern which is consisted of both pole of magnet without landmarks and additional sensors, and it control the backward movement using up-and-down rotating type differential drive unit instead of common drive units. Proposed MGV considers KF(Kalman filter) to improve the localization accuracy. To verify the performance of proposed method, we designed MGV for the experiment. As the results, we can confirm the performance of propoesed method to recognize the pattern and to control the backward movement. With respect to localization, proposed method has the less RMSE about 5.6904 mm than previous method.

• Korean Journal of Optics and Photonics
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• v.24 no.2
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• pp.77-85
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• 2013

The precision of retardation measurement has been improved upto $3{\sigma}$ <0.005 nm after improvements are made to the conventional transmission ellipsometer. Improvements are made such that, i) the polarizer module instead of the sample stage is rotated, ii) the light source is replaced, iii) the starting points of two rotating modules are accurately synchronized, and iv) the fine background retardation is compensated. Together with the newly introduced RVD (Retardation Vector Difference) method, the improved instrument is successfully applied to characterize the ultra small optical birefringence of the rubbed polyimide alignment layer, after the residual retardation due to glass substrate whose magnitude is about 1.0 nm is properly subtracted. It is verified that the net retardation of the alignment layer ranges from 0.05 nm to 0.15 nm.

• Applied Chemistry for Engineering
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• v.34 no.4
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• pp.383-387
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• 2023

The quartz crystal microbalance (QCM), commonly used in high vacuum deposition, becomes difficult to use when a thick film is deposited on the quartz, affecting the crystal's inherent vibration. In this study, a non-destructive optical measurement method was developed to measure the film's deposition rate during the in-situ film deposition process. By measuring the scattered laser intensity caused by the dimer in the parylene gas passing through the gas flow path, it was successfully confirmed that the ratio of the dimer in the parylene gas increases as the pyrolysis temperature decreases. Additionally, it was noted that the film's thickness and haze increase as the pyrolysis temperature decreases by confirming the characteristics of the visible parylene films. Through the research results, we aim to utilize the stable in-situ film deposition rate measurement system to control the precise film deposition rate of parylene films.