• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.475-478
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• 2006

In electrical impedance tomography (EIT) an array of electrodes is attached on the boundary of an object and small alternating currents are injected through these electrodes, and then the resulting voltages are measured. An estimation for the cross-sectional resistivity distribution in the object is obtained by using these current and voltage data in a nondestructive manner. In this paper, the electrical impedance imaging of two-phase flows undergoing rapid transient is considered with a special emphasis on the effect of the current pattern on the image reconstruction. The trigonometric current pattern, which is commonly used in the conventional static electrical impedance imaging, shows poor performance in case of the dynamic imaging considered in this work. Extensive numerical experiments are conducted with various kinds of current patterns and their effects on the image reconstruction performance are examined.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.231-232
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• 2008

The effect of n-electrode patterns on the current distribution in active region is investigated in GaN-based blue vertical light emitting diodes (VLEDs). A 3-dimension circuit model is adopted to analyze the current flow patterns in VLEDs. We had fabricated VLEDs having different n-electrode patterns, measured their current-voltage characteristics, and compared to the numerical simulation. It turns out that the current spreading in VLEDs is strongly dependent on the n-electrode pattern. Some design guidelines for n-electrode patterns to produce uniform current injection are presented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.529-532
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• 2003

Quench behavior of resistive superconducting fault current limiters (SFCLs) with various pattern shapes was investigated. The pattern shapes employed were meander, bi-spiral, and spiral shapes of identical line width, gap and margin. SFCLs were fabricated from YBCO thin films grown on two-inch diameter $Al_2O_3$ substrates under the same conditions. Resistance rise of current limiting elements was low at a spiral shape before the whole quench completion, which may act as a disadvantage for simultaneous quench in serial connection between current limiting elements, but the temperature tended to have similar values at higher voltages. On the other hand, bi-spiral shape was severe at insulation level between current limiting lines. When these aspects were considered, we concluded that a meander shape was appropriate to design for a resistive SFCL based on thin films except the concentration of electric field at edge areas of strip lines.

• Journal of Industrial Technology
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• v.24 no.A
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• pp.109-117
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• 2004

This paper presents a current control strategy to reduce torque ripple of Brushless DC Motor in commutation period with PWM pattern. The torque ripple is mainly caused by the inequality in the rate of change between rising current and decaying one during commutation. And also it is influenced by the shape of real back EMF. Therefore, in the proposed control strategy, considering real back EMF a compensation voltage is generated to equalize the rate of change in these commutating currents. And then, by providing the compensation voltage in commutation period with PWM pattern, the torque ripple can be reduced. The simulation and experimental results verify that the proposed method can reduce the torque and the current ripples significantly.

• Journal of ILASS-Korea
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• v.21 no.3
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• pp.155-161
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• 2016

Injected fuel pressure waves of a common rail injector with various current profiles supplied to the injecor were measured using Bosch method. In order to drive the common rail injector, the current in the solenoid should be controlled using what is known as a peak and hold pattern, which consists of a high current level with a short time duration (peak) in the first step and a low current level with a long time duration (hold) in the subsequent step. The current profile can be shaped by swithcing an injector driving power source with the peak and hold waves. The capture, compare and PWM (CCP) pin in the microprocessor was used to generate the combined peak and hold waves. The PWM square wave generated from the CCP pin has a duty ratio of 100% for the peak current and 10% or 30% for the hold pattern. Five patterns of the current profile were generated by combining the peak and hold wave. The common rail pressure is controlled at 75, 100, and 130 MPa. As the fuel rail pressure increases, the variations of the measured fuel injection pressure wave according to the current profiles decrease.

• Journal of IKEEE
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• v.7 no.1 s.12
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• pp.22-31
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• 2003

Conventional stimulus patterns have used DC for discrimination of acupoint and meridian which is the basic object of diagnosis and medical treatment in oriental medicine. Those discriminate conduction points by stimulation on body skin with DC. But, it is insufficient to reliability in discrimination ratio, coincident ratio, body effect, reproductivity. Therefore, this paper has extracted the optimal parameter of frequency and waveform in order to improve conventional pattern, and proposed the SPAC(Single Power Alternative Current) stimulus pattern applying that. Also, We proposes algorithm which is able to discriminate with low pressure of the electrode by displaying in the level meter both the absolution and relation value of the skin current. It can decrease pain and body effect by electrode pressure and discriminate acupoint regardless of skin current in difficult discrimination spot. We have compared the performance of system applying the extracted optimal parameter and algorithm. We have compared discrimination, coincident ratio of both conduction point and traditional acupoints by acupoint stimulation pattern. In the results, we confirmed reliability of SPAC stimulus pattern.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1308-1311
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• 2007

Leakage current produced by backside illumination on bottom-gated amorphous silicon thin film transistor has been investigated. The experimental results show that the leakage current of bottomgated structure is significantly dependent on the shape of amorphous silicon pattern. A proper design of amorphous silicon pattern has been suggested in viewpoint of reducing the leakage current as well as mass production.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.212-216
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• 1996

Recently, with the development of NC and CNC machine tools and the high labor wage, the cutting process requires the high speed and automatic system which uses industrial robots and the flexible manufacturing system(FMS) that combines several machine tools. In this system, the whole system can be influenced by just one of the machin tools. So it needs to detect a problem and to solve it immediately In in-process state. The monitoring system through measuring the motor current with current sensor has been attracting the attention of lots of researchers view of its low cost and flexibility. By using the pattern discriminant with the detected three-phase-current signal, that is, $I_{RMS}$, a system which can monitor and analyze abnormal machining process condition of the workpiece during the machining will be able to be developed in this research.h.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.2080-2081
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• 2007

In this paper, the polymer insulators which had been used for electrical insulation were investigated surface leakage current and deterioration pattern. Because the electrical fault took place at the dust occurrence area due to environmental pollution. In particular, the dust accumulates easily on insulation material which is exposed an external long time. The leakage current brings out electrical fault after all. Also, it is need to variation of material and shape to repress a leakage current on electrical material. In this paper, we measured a leakage current on electrical material of facilities by dust, and in experiments the prevention to electrical fault was studied.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.6
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• pp.1253-1272
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• 2010

In this paper, we propose a new affine shape adaptation scheme for the affine invariant feature detector, in which the convergence stability is still an opening problem. This paper examines the relation between the integration scale matrix of next iteration and the current second moment matrix and finds that the convergence stability of the method can be improved by adjusting the relation between the two matrices instead of keeping them always proportional as proposed by previous methods. By estimating and updating the shape of the integration kernel and differentiation kernel in each iteration based on the anisotropy of the current second moment matrix, we propose a coarse-to-fine affine shape adaptation scheme which is able to adjust the pace of convergence and enable the process to converge smoothly. The feature matching experiments demonstrate that the proposed approach obtains an improvement in convergence ratio and repeatability compared with the current schemes with relatively fixed integration kernel.