• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.137-137
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• 2003

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.108-108
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• 2003

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.9
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• pp.1060-1069
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• 2019

Pedestrian-based camera self-calibration methods are suitable for video surveillance systems since they do not require complex calibration devices or procedures. However, using arbitrary pedestrians as calibration targets may result in poor calibration accuracy due to the unknown height of each pedestrian. To solve this problem in the real surveillance environments, this paper proposes a novel Bayesian approach. By assuming known statistics on the height of pedestrians, we construct a probabilistic model that takes into account uncertainties in both the foot/head locations and the pedestrian heights, using foot-head homology. Since solving the model directly is infeasible, we use variational Bayesian inference, an approximate inference algorithm. Accordingly, this makes it possible to estimate the height of pedestrians and to obtain accurate camera parameters simultaneously. Experimental results show that the proposed algorithm is robust to noise and provides accurate confidence in the calibration.

• Korean Journal of Optics and Photonics
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• v.11 no.5
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• pp.317-322
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• 2000

We present a compensation method of the phase change upon reflection in the scannll1g whIte light interferometry. which pracl1cally allows precIse 3-D profIle mappmg for compo~Ite target surfaces comprising of multipledissinular matenals. The compensation method estimates the vanatlon 01 pbase change with the spectral distribution of the light source through first-order approximation, and then diIectly compensates the measurement errors by perIormmg two-wavelength white light intetferomctric measurements. Experimental results prove that the proposed self-compensatIOn mcthod is capable of reducing the measmement error in step height gauging within $\pm2nm$..

• Korean Journal of Optics and Photonics
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• v.13 no.2
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• pp.98-104
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• 2002

We present a new self-calibration method to remove the systematic error of a 2-axis lateral shearing interferometer that has been specially designed for optical testing of aspheric optics. The method takes multiple measurements by rotating the test optics and extracts the systematic error by fitting the measured wavefronts into the Zernike polynomials. The method works with arbitrary azimuthal angles for test optics rotation, which offers an advantage of correcting the error induced by the non-orthogonality of the two axes of wavefront shearing as well as the error caused by the optical components of the interferometer system itself.

• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.503-510
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• 2020

Concrete is one of the most widely used materials as the shielding structures of a nuclear facilities. It is also the most generated radioactive waste in quantity while dismantling facilities. Since the concrete captures neutrons and generates various radionuclides, radiation measurement and analysis of the sample was fulfilled prior to dismantle facilities. An HPGe detector is used in general for the radiation measurement, and effective correction factors such as geometrical correction factor, self-absorption correction, and absolute detector efficiency have to be applied to the measured data to decide exact radioactivity of the sample. Correction factors are obtained by measuring data using a standard source with the same geometry and chemical states as the sample under the same measurement conditions. However, it is very difficult to prepare standard concrete sources because concrete is limited in pretreatment due to various constituent materials and high density. In addition, the concrete sample obtained by core drill is a volumetric source, which requires geometric correction for sample diameter and self absorption correction for sample density. Therefore in recent years, many researchers are working on the calculation of effective correction factors using Monte carlo simulation instead of measuring them using a standard source. In this study we calculated, using Geant4, one of the Monte carlo codes, the correction factors for the various diameter and density of the concrete core sample at the gamma ray energy emitted from the nuclides ¹⁵²Eu and ⁶⁰Co, which are the most generated in radioactive concrete.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.379-382
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• 2002

Among the CMM calibration techniques, the calibration with standard specimen is most accurate way to acquire the required precision. When there is no standard specimen, the calibration of CMM with itself is possible. This calibration method is called "self-calibration". In this paper, we developed self-calibration algorithm for CMM XY plane. It is possible to calculate the in-plane error and out-of-plane error of CMM with 3 different measurement of same artifact. Experimental result shows that the non-orthogonality error is dominant in in-plane error and the self-calibration result and laser interferometer measured result have almost same value.ame value.

• Journal of Preventive Medicine and Public Health
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• v.32 no.3
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• pp.355-360
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• 1999

Objectives: This 3-year longitudinal study was conducted to evaluate the influence of self-rating health perception on health care utilization and all cause-death risk. Methods: The hypothesis was tested using a community-based samples, among which subjects 3,414 were interviewed in 1995, Self-rating health perception was assessed by single-item question. Three components of health care utilization amount(number of visits, number of medications, yearly health care expenses) per year were measured using medical insurance data during 3-year follow-up period among subjects in district health care insurance. There were 123 deaths from all causes among 3,085 subjects interviewed. Results: The results showed that those who had poor health perception revealed more increases in the amount of health care utilization than good health perception group (p<0.05). After adjusting for age and sex, the poor health perception group had higher death risk over 3 years than good health perception group(hazard ratio=1.88). but, after adjusting health care utility, supplementary, was not significant. Conclusion: These results suggest that self-rating health perception was associated with difference in health care utilization and all cause-death risk.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.10
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• pp.91-97
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• 2013

In this paper, a current steering 10-bit CMOS D/A converter to drive a NTSC/PAL analog TV is proposed. The proposed D/A converter has a 50MS/s operating speed with a 6+4 segmented type. Further, in order to minimize the device mismatch, a self-calibration bias technique with a fully integrated termination resistance is discussed. The chip has been fabricated with a 3.3V 0.11um 1-poly 6-metal CMOS technology. The effective chip area is $0.35mm^2$ and power consumption is about 88mW. The experimental result of SFDR is 63.1dB, when the input frequency is 1MHz at the 50MHz of sampling frequency.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.345-346
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• 2006