• Journal of Electrical Engineering and Technology
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• 제2권3호
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• pp.401-407
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• 2007

Precise absolute measurement of the errors in a potential transformer (PT) can be achieved using high voltage capacitance bridge (HVCB) and capacitive divider. The uncertainty in a PT measurement using the HVCB system was evaluated by considering the overall factors affecting during the calibration of a PT. The expanded uncertainties are found to be not more than $30{\times}10^{-6}$ for ratio and $30{\mu}rad$ for phase up to the primary voltage of $V_p=22kV$. For same PTs, the measured errors in KRISS (Korea Research Institute of Standards and Science) using our bridge are well coincide with those in NMIA (National Measurement Institute of Australia) and PTB (Physikalisch-Technische Bundesanstalt) within the corresponding uncertainties.

• Journal of Sensor Science and Technology
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• 제14권6호
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• pp.381-386
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• 2005

A Co-C eutectic cell for thermocouple calibration was manufactured and tested to investigate its phase transition characteristics using Type B thermocouples. It was observed that the freezing plateaus were flatter than those of melting, but the melting points were closer to the true transition temperature than the freezing points. The expanded uncertainty of melting temperature was calculated not to exceed $0.2^{\circ}C$ (k = 2). Based on the observed results, the melting process is recommended for the calibration of thermocouples.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.3-7
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• 2003

In this paper, radar scattering coefficients of earth surfaces such as grass fields, rice fields and bare soil surfaces are measured by using an auto-mounted network analyzer-based scatterometer system. The scatterometer system is calibrated both the magnitude and phase in order to obtain the accurate Mueller matrices of the earth surfaces. Then the accurate scattering matrices can be obtain from the Mueller matrices. The degree of correlation $\alpha$ is also obtained by this procedure and is used to correct AirSAR data which are not calibrated with phase variations.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.41-45
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• 2006

To get accurate positions of GPS antennas, one should apply phase center variations (PCV) corrections in the data processing. Until recently, relative calibrations, originally proposed by National Geodetic Survey of United States, were the international standard. However, in late 2006, International GNSS Service will switch to absolute calibration methods. In this study, we compared the position differences caused by different PCV models, and their effects on the calculations of Precipitable Water Vapor (PWV) in the atmosphere. Data from ${\sim}40$ permanent GPS stations in Korea were processed and we found that the vertical position differences reach up to 5 cm, depending on the model selected. Also the PWV values varied quite significantly: the maximum bias in the computed PWV values was ${\sim}4$ mm.

• Journal of the Korea Institute of Military Science and Technology
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• 제22권4호
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• pp.467-474
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• 2019

Recently, optical phased array(OPA) based laser detection and ranging(LADAR) has gained great interest to replace the traditional mechanical light detection and ranging technique(LiDAR). In OPA-based LADAR, it is well known that phases of laser pulses traveling through each of channels should be the same to obtain a narrow free-space single beam without noise-like ripples in the far field. However, it is difficult to provide such ideal condition due to the fabrication errors. To tackle this problem, any algorithms should be necessary to compensate the initial random phases of each channel in OPA antenna. In this paper, we propose a hill-climbing based phase calibration algorithm and evaluate the performance of the proposed algorithm.

• Journal of the Optical Society of Korea
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• 제10권4호
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• pp.178-183
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• 2006

An in-line phase-shifting digital holographic microscopy system was constructed by inserting a conventional microscope in the object arm of a Mach-Zehnder interferometer. It was used to measure the three dimensional shape of a micro Fresnel lens. It was also shown that both the lateral and the axial resolutions of the in-line phase-shifting system using a self-calibration algorithm were superior to those of the best off-axis system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2010년도 춘계학술대회 논문집
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• pp.126-127
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• 2010

• Applied Microscopy
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• 제33권3호
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• pp.195-204
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• 2003

The Experimental calibration method has been investigated to correct d-spacing estimation and to identify phases in the electron diffraction data acquired by imaging plates. When the diffraction data from the imaging plate was corrected by the d-spacing calibration method with the radial intensity distribution plotting in this experiment, The accuracy of d-spacing estimation was significantly increased in errors of about 0.5%. The experimental calibration equation followed up the first order exponential decay function was derived from the trace of d-spacing deviation between the measured and the calculated values. It was applied to the analysis of d-spacing and the phase identification of the transitional phases formed from [001] gibbsite specimen by electron beam irradiation effect. In this case more accurate phase identification and d-spacing evaluation is possible for the transitional phases whose diffraction patterns are complicatedly superimposed. It is concluded that ${\chi}$-alumina, ${\gamma}$-alumina and ${\sigma}$-alumina are clearly identified as the major transitional phases formed from gibbsite by electron beam irradiation for 120 min.

• Journal of the Korean Chemical Society
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• 제8권2호
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• pp.47-56
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• 1964

When a developed paper partition chromatogram was irradiated by means of the pneumatic tube system of the Korean research reactor (neutron flux: 1.5 ${\times}10^{12}n/cm^2$sec.) the qualitative confirmation of the developed spot on the chromatogram was possible. In the case of an organic halogen compounds (chloro-acid, chloro-ester, iodide, and fluoride) the spot analysis was possible by the present method whereas the same spot could not give the distinct coloring with a common coloring reagents. Filterpaper thickness calibration and activity calibration induced by irradiation of the components of the filter paper, which were a source of erraneous interpretation of the spot, were searched and an average filterpaper calibration method and filter paper activity were improvised to obtain a good qualitative analysis of the spot. Finally the use and applicability of this method for the analysis identification of an organic halogen compound were evaluated. As the filter paper phase an ordinary phase (Whatmann #1, filter paper) and reversed phase (liquid paraffin impregnated) were used.

• Journal of Broadcast Engineering
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• 제24권6호
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• pp.965-973
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• 2019

In this paper, Stereo 4K@60fps 360 VR real-time video capture system which consists of video stream capture, video encoding and stitching module is been designed. The system captures stereo 4K@60fps 360 VR video by stitching 6 of 2K@60fps stream which are captured through HDMI interface from 6 cameras in real-time. In video capture phase, video is captured from each camera using multi-thread in real-time. In video encoding phase, raw frame memory transmission and parallel encoding are used to reduce the resource usage in data transmission between video capture and video stitching modules. In video stitching phase, Real-time stitching is secured by stitching calibration preprocessing.