• Journal of the Korean Society of Safety
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• v.23 no.4
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• pp.13-18
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• 2008

This study deals with finish roll forming by forced displacement can be conceived as a method of eliminating errors in conventional form rolling under constant loads. This method produces a high-precision tooth profile by low-speed form rolling when a high rigid screw or cam is used at the pressurized section. Tooth profile is decided in the beginning of roll forming and ${\delta}_{max}$ mainly increases if the number of roll forming process is increased. Gear class is improved by one or two class after roll forming if the gear has convex type error and pressure angle error in KS 4 class. If the gear have concave type error and pressure angle error and pressure angle error, gear class is not improved in theory, but improved a little in practice. In the finishing roll forming, it inevitably yields both the concaving of tooth profile and plastic deflection of addendum of teeth. Experiments show that the concaving and the plastic deflection are successfully reduced, the accuracy of tooth profile reaches to KS 0 class.

• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.225-233
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• 2001

Distortion of Secondary Ion Mass Spectrometry(SIMS) depth profile, which is usually observed when the analysis is made using oxygen flooding on the surface of Si with oxide on it, has been corrected. The origin of distortion has been attributed to depth calibration error due to sputter rate difference and concentration calibration error due to relative sensitivity factor(RSF) difference between $SiO_2$ and Si layers, In order to correct depth calibration error, artifact in analysis of sodium ion on oxide was used to define the interface in SIMS depth profile and oxide thickness was measured with SEM and XPS. The differences of sputter rate and RSF between two layers have been attributed to volume swelling of Si substrate occurred by oxygen flooding induced oxidation. The corrected SIMS depth profiles showed almost the same results with those obtained without oxygen flooding.

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.119-138
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• 1998

Recently measurements of atmospheric trace gases from satellite are vigorous. So the development of its data processing algorithm is important. In this study, retrievalof vertical ozone profile from the atmospheric transmittance measured by satellite solar occultation method and its sensitivity to temperature and pressure are investigated. The measured transmittance from satellite is assumed to be given by the limb path transmittance simulated using annual averaged Umkehr data for Seoul. The limb path transmittance between wavelengths $9.89{\mu}m$ and $10.2{\mu}m$ is simulated with respect to tangent heights using the ozone data of HALOE SIDS(Hallogen Occultation Experiment Simulated Instrument Data Set) as an initial profile. Other input data such as pressure and temperature are also from HALOE SIDS. Vertical ozone profile is correctly retrieved from the measured transmittance by onion-peeling method from 50km to 11km tangent heights with the vertical resolution of 3km. The bias error of $\pm0.001$ in measured transmittance, the forced error of $\pm3K$ in each layer temperature, and the forced $\pm3%$ error in each layer pressure are assumed for sensitivity tests. These errors are based on the ADEOS/ILAS error limitation. The error in ozone amount ranges from -6.5% to +6.9% due to transmittance error, from -9.5% to +10.5% due to temperature error, and from -5.1% to +5.4% due to pressure error, respectively. The present study suggests that accurate vertical ozone profile can be retrieved from satellite solar occultation method. Accuracy of vertical temperature profile is especially important in the retrieval of vertical ozone profile.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.613-617
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• 2000

This paper descries the effect of the stylus tip size on the measuring error in surface topography measurement. To analyze the distortional effect of an actual surface geometry originating from the finite stylus size, the surface is modeled as a sinusoid and the stylus tip as a circle. the measuring error is defined as the ratio of the standard deviation of a tracing profile and an original profile. It is shown that this measuring error depends on the amplitude and wavelength of an original profile. In this paper, the spectrum analysis is applied to investigate the distortional effect due to the mechanical filtering of the stylus in the frequency domain. and, the cumulative power spectrum is applied to determinate the minimum wavelength limits to be measured with the various stylus tip radius from these results, a new method to select proper stylus tip radius is proposed.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1685-1690
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• 2010

This paper describes the calculation and application of the speed profile for the train speed control when the train is operated by ATO(Automatic Train Operation). We propose a speed profile calculation method considering the speed limitation and the jerk limitation, in order to maintain the quality of the train automatic operation. In previous works, ATO calculates a desired speed profile along the time, and controls the train to follow the profile. In this case, it may be hard to follow the restrictive speed along the location or to stop the train with a low location error, because of the difference between the desired location at each time and the real location of the train due to the control error. In the proposed method in this paper, we calculate a desired speed profile along the time considering the speed and jerk limitation first, and derive a speed profile along the location using it. If the restrictive speed profile is changed or the train speed strayed from the speed profile, ATO system calculates new speed profile and applies it immediately. Because ATO system controls the train speed based on the train location, the accuracy of the train location control can be improved. A simulation system for the test of the automatic train operation using this method is designed.

• Journal of the Korean Solar Energy Society
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• v.32 no.2
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• pp.74-86
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• 2012

For the improvement of environmental comfort in the buildings with the blind control, the objective of this study is to prevent the direct glare caused by the daylight inlet. During the process of solar profile prediction, time are significant factors that may cause error and glare during the blind control. This research proposes and evaluates the correction and control method to minimize prediction error. For the local areas with different longitude and local standard meridian, error occurred in the process of the time conversion from local standard time to apparent solar time. In order to correct error in time conversion, apparent solar time should be recalculated after adjusting the day of year and the equation of time. To solve the problems by the potential time errors, control method is suggested to divide the control sections using the calibrated fitting-curve and this method is verified through simulations. The proposed correction and control method, which considered potential time errors by loop lop leap years, could solve the problems about direct glare caused by daylight inlet on the work-plane according to the prediction errors of solar profile. And also these methods could maximize daylight inlet and solar heat gain, because the blocked area on windows could be minimized.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.6
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• pp.76-81
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• 2006

In this paper, profile error measurement method of a turbine blade using 3D-scanner is developed. The method begins with scanning the upper and lower sides of the blade on which three small balls are attached, and constructs a solid measurement model by registering the two scanned surfaces. Airfoils are derived from the model at each interval by intersecting it with a plane, and arranged with design airfoils. The $2^2$ factorial design search method is engaged in arranging the two airfoils, from which the main blade parameters including the edge radius are computed. The developed measurement technique is applied to practical blade manufacturing and validates its effectiveness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.839-840
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• 2012

본 논문에서는 3 축 기계장비의 공간오차를 예측하기 위한 사전 단계로 각 축에 대하여 레일형상오차를 측정하였다. 전용 측정지그를 설계/제작하여 이 지그가 이동함에 따라 혼합축차이점법을 이용하여 레일형상오차를 측정하였다. 레일형상오차로부터 테이블 운동오차를 예측하고, 이와 더불어 각 축 사이의 직각도 오차를 측정한 후 이로부터 최종적으로 3 축 장비에 대한 공간오차를 평가할 예정이다. 예측된 공간오차는 실제 레이저를 이용한 공간오차 측정방법을 이용하여 검증할 예정이다.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1012-1016
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• 2004

In this paper, we propose a simple but optimized NC code generating technique for disk cams by means of tool path error control in a five-axis CNC machining center. Using the geometric theorem of the triangle made between manufacturing points and error checkpoint, the tool path error has been studied for disk cams profile generation and an improvement in the profile has been obtained. Then, based on the present manufacturing approach a computer program is developed on $C^{++}$ language to perform and to verify the shape design, the manufacturing simulation, and the optimized generation of the NC code.

• Journal of Mechanical Science and Technology
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• v.20 no.3
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• pp.345-357
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• 2006

By employing the concept of equivalent linkage, this paper presents an analytical method for analyzing the mechanical errors of disk cam mechanisms with a flat-faced follower. The resulting error equations do not really involve the location of the curvature center of the cam profile, and locating the curvature center of the cam profile is not essential. The resulting errors are significantly affected by the pressure angle, and the smaller pressure angle will result in the smaller mechanical error. In the worst case, owing to the joined effects of various design parameters, the accuracy of the follower motion may degrade considerably. For the oscillating follower case, all acceleration error functions have a sudden change at every beginning and at every end of the motion even though the theoretical follower displacement is cycloidal motion.