• Proceedings of the IEEK Conference
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• 2000.11d
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• pp.239-242
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• 2000

The color television signal and color receivers should be balanced for the same value of reference white to achieve colorimetric fidelity and to minimize interference. The NTSC signal is balanced for white at 6774 K and most existing receivers are balanced between 6500 K and 10000 K for many reasons. In this paper, we analyze beam current ratio, lightness, and channel gain ratio according to the color temperature for the three-tube projection HDTV. We also propose the brighter reference white for the three-tube projection HDTV based on the Helmholtz-Kohlrausch effect and the optical resolution of the image. In computer simulation we confirmed the most suitable reference white using the proposed analysis method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.218-218
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• 2003

• Journal of the Korean Society for Nondestructive Testing
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• v.4 no.2
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• pp.7-14
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• 1985

An experiment to investigate the rate of change of phase angle of eddy current output signal caused by outer surface defect of nonferromagnetic tube by variation of standard depth of penetration and variation of percent of tube wall penetration was carried out. The results of the experiment show that the phase angle of defect signal is increased with decreasing the standard depth of penetration or the depth of defect. The results also show that the phase angle is decreased with increasing the skin effect of eddy current, and that the resolution is decreased with decreasing the depth of defect.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.159-165
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• 2008

In this paper the signal analysis of eddy current test using transmit-receive(T/R) pancake coil of ECT array probe using electromagnetic finite element method(FEM) is performed. For characteristics analysis, the notch defect is used. The depth of defect is 40[%] of steam generator tube thickness, and inside defect and outside defect are used as simulation examples. The signal analysis is performed according to the variation of receive coil position. The receive coil is positioned $0[^{\circ}]$, $30[^{\circ}]$, $60[^{\circ}]$, $90[^{\circ}]$ of circumferential position of transmit coil. To obtain e electromagnetic characteristics of robes, the governing equation is derived from Maxwell's equations, and the problem is solved using the 3-dimensional finite element method. The signal magnitude of inside defect is bigger than that of outside defect, and the signal difference can be seen according to the variation of position of receive coil. The experimental signal and numerical signal of ASME standard tube show similar results. The results in this paper can be helpful when the ECT signals from ECT array probe are evaluated and analyzed.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.54-58
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• 2009

In this paper, the ECT(eddy current testing) signal analysis of eddy current array probe for inspection of SG(steam generator) tube in NPP(nuclear power plant) using electromagnetic FEM(finite element method) was performed. To obtain the electromagnetic characteristics of probes, the governing equation was derived from Maxwell's equation, and the problem was solved by using the 3-dimensional FEM. The types of defects were FBH(flat bottomed hole) and OD groove, Spiral groove, natural defects(pitting, SCC, multiple SCC, wear). The depth of FBH defects were 20%, 40%, 60%, 80%, 100 of SG tube thickness, and it was assumed that the defects were located on the tube outside. And the operation frequency of 100kHz, 300kHz and 400kHz were used. Material of specimen was Inconel 600 which is usually used for SG tubes in NPP. The signal difference could be observed according to the variation of size and depth on FBH defects and operation frequencies. The results in this paper can be helpful when the ECT signals from EC array probe are evaluated and analyzed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.6 s.249
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• pp.497-504
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• 2006

A Coriolis mass flowmeter(CMF), which has U-Shaped unique measurins tube was developed fo. direct mass flow measurement. In order to convert the time difference between two measuring tubes motion into mass flowrate and flow quantity, a signal processing circuit, as a part of CMF, was also developed. The CMF was designed as the 15 mm nominal diameter of pipe connection and the 8 mm stainless steel(sus 316) pipe was used for measuring tube. To maximize the flow signal(time difference) from the measuring tubes, the natural frequency of measuring tube was adjusted as 220 Hz, which is same as the frequency of exciter. The maximum displacement at the end of the measuring tube was measured as 0.05 mm and the maximum time difference between two measuring tubes was observed as $20{\mu}s$, which was proper for discrimination and measuring range of CMF. The developed CMF was tested against the gravimetric flowmeter calibrator in the range of 3 kg/min and 30 kg/min. The results showed that the CMF has good linearity and repeatability in the tested flow range. Large size of CMF base on the current study experience will be developed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.833-846
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• 1988

Two-phase flow heat transfer phenomena with flash evaporation inside a vertical tube were studied experimentally. Void fractions were measured using electrical probes, and the flow patterns were identified from the output voltage signal itself. The flow pattern as well as the beat transfer rates were changing along the axial distance from the tube inlet with the system pressure. As the pressure inside the tube decreases with fixed inlet temperature, the overall heat transfer coefficient through the tube wall and the boiling heat transfer coefficient inside the tube increase whereas the condensation heat transfer coefficient outside the tube decreases. The boiling heat transfer coefficient inside the tube measured by the experiments appeared to be somewhat larger than the value obtained from the Chen's correlation. Also, the flow patterns identified from present experiments are at the larger quality region of the low pattern map based on the transition criteria of Mishima and Ishii. This may be due to the non-equilibrium flashing phenomenon occurred at the nozzle exit and the tube inlet ; this also implies that the flow pattern of the two-phase flow depends strongly on the inlet conditions.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.493-496
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• 2005

For home healthcare, the unconstrained measurement of physiological signal is highly required to avoid the inconvenience of users. The recording and analysis of the fundamental parameters during sleep like respiration and heart beat provide valuable information on his/her healthcare. Using the air mattress sensor system, the respiration and heart beat movements can be measured without any harness or sensor on the subject's body. The differential measurement technique between two air cells is adopted to enhance the sensitivity. The balancing tube between two air cells is used to increase the robustness against postural changes during the measurement period. The meaningful frequency range could be selected by the pneumatic filter with balancing tube. ECG (Electrocardiography) and respiration sensor (plethysmography) were measured for comparison with the signal from air mattress. To extract the heart beat information from air pressure sensor, digital signal processing technique was used. The accuracy for breathing interval and heart beat monitoring was acceptable. It shows the potentials of air mattress sensor system to be the unconstrained home sleep monitoring system.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.4
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• pp.330-337
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• 2010

In this paper, 3-dimensional electromagnetic numerical analysis is performed about the eddy current(EC) array probe characteristic which is the next generation probe for accurate diagnosis of steam generator(SG) in nuclear power plants(NPPs). ASME(American Society of Mechanical Engineers) Standard and X-probe combo calibration standard tube are selected for acquisition of eddy current testing(ECT) signals and this result of compared with the real test signals for reasonability of result. Based on the analysis result of calibration standard tube, ECT signals that are about the defects of pitting, stress corrosion cracking(SCC), multiple SCC and wear is obtained. Material of specimen was Inconel 600 which is usually used for SG tubes in NPPs. The operation frequency of 300 kHz were used. The signal characteristics could be observed according to the various defects. The results in this paper can be helpful when the ECT signals from EC array probe are evaluated and analyzed.

• The Journal of the Korea Contents Association
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• v.19 no.12
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• pp.517-526
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• 2019

The purpose of this study is to find the optimal method for clinical application by analyzing image quality and radiation output according to parameter combination when using the Automatic Exposure Control (AEC). The experimental method combines 70, 81 kVp with sensitivity S200, S400, S800 and S1000 of the Automatic Exposure Control for Entrance Surface Dose (ESD), current volume, Signal to Noise Ratio (SNR), Contrast to Noise Ratio (CNR), Time-to-Radiation Dose Curve in abdomen and pelvis. And then, image quality and radiation output stability were evaluated. As a results, Entrance Surface Dose, current volume, Signal to Noise Ratio, Contrast to Noise Ratio decreased as the tube voltage and sensitivity were set higher. In addition, the higher tube voltage and sensitivity, the Time-to-Radiation Dose Curve showed a poor output stability. In conclusion, the higher the combination of tube voltage and sensitivity in the use of Automatic Exposure Control, the more problems can be seen in image quality and stability of the radiation output. Therefore, a relatively low combination of tube voltage and sensitivity showed that the image quality and radiation output stability could be optimized by minimizing the error range that would occur when the detector recognized a combination of parameters.