• Journal of Power Electronics
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• 제18권1호
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• pp.300-308
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• 2018

An online estimation method for wireless power transfer (WPT) systems is presented without using any measurement of the secondary side or the load. This parameter estimation method can be applied with a controlling strategy that removes both the receiving terminal controller and the wireless communication. This improves the reliability of the system while reducing its costs and size. In a wireless power transfer system with an LCCL impedance matching circuit under a rectifier load, the actual load value, voltage/current and mutual inductance can be reflected through reflected impedance measuring at the primary side. The proposed method can calculate the phase angle tangent value of the secondary loop circuit impedance via the reflected impedance, which is unrelated to the mutual inductance. Then the load value can be determined based on the relationships between the load value and the secondary loop impedance. After that, the mutual inductance and transfer efficiency can be computed. According to the primary side voltage and current, the load voltage and current can also be detected in real-time. Experiments have verified that high estimation accuracy can be achieved with the proposed method. A single-controller based on the proposed parameter estimation method is established to achieve constant current control over a WPT system.

• 반도체디스플레이기술학회지
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• 제22권2호
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• pp.64-71
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• 2023

If an impedance mismatch occurs between the source and load in a Radio Frequency transmission system, reflected power is generated. This results in incomplete power transmission and the generation of Reflected Power, which returns to the Radio Frequency generator. To minimize this Reflected Power, Impedance matching is performed. Fast and efficient Impedance matching, along with converging reflected power towards zero, is advantageous for achieving desired plasma characteristics in semiconductor processes. This paper explores Impedance matching by adjusting the Vacuum Variable Capacitor of an L-type Matching Module based on the trends observed in the voltage of the Phase Sensor and Electromotive Force voltage. After assessing the impedance matching characteristics, the findings are described.

• Journal of Acupuncture Research
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• 제36권2호
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• pp.88-91
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• 2019

Background: The intelligent tissue hypothesis on how acupuncture works, states that real-time organ states are reflected in the tissue at an organ's related acupuncture points (acupoints). Any such changes in the tissue would produce corresponding changes in the impedance at those locations. Methods: To test this hypothesis in relation to the lungs, the impedance at key lung-related acupoints was monitored in real time while the patient breathed normally, then breathed deeply, then quickly, then held his breath. Results: When breathing deeply this produced a notable decrease in the impedance at 1 acupoint, while breathing quickly produced a decrease at another acupoint, suggesting that these different functions taxed different aspects of the lungs, which was then reflected at different acupoints. The impedance at all the acupoints also contained low-amplitude waves that reflected the base rate of the respiration pacesetter, and the amplitude of these waves also varied to reflect different real-time states in the lungs. Conclusion: These real-time impedance patterns suggested that corresponding physical patterns were present in the tissue at these acupoints, and these physical patterns mirrored the real-time variations in function strength of the related organ (the lungs). These results were consistent with the hypothesis.

• Journal of Acupuncture Research
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• 제36권1호
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• pp.21-27
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• 2019

Background: The intelligent tissue hypothesis holds that an organ's states (be it normal function or stressed states) are reflected in real time at its related acupuncture points (acupoints), causing physical, real-time changes in the local tissue. The experiment was devised to test this. Methods: The patient drank chilled water while the impedance at 6 stomach-related acupoints was monitored in real time (sample rate of 1 kHz). Any changes in the local tissue at the acupoints ought to be reflected in changes in the impedance. Results: The impedance at every test acupoint showed a response to the chilled water being ingested. Also, the duodenal pacesetter and the stomach's slow waves were clearly visible in the impedance pattern at all the acupoints. Conclusion: Hence, many separate details of the stomach's function were reflected at these acupoints. The duodenal features were consistent with the traditional indications for these acupoints, which are noted to be able to treat intestinal conditions. Therefore, the results were consistent with the hypothesis and also provided a possible explanation for how the use of these acupoints is able to treat intestinal conditions.

• 한국전자파학회논문지
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• 제25권6호
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• pp.679-689
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• 2014

본 논문에서는 무선 전력 전송 시스템에서 시간에 따라 변하는 반사 임피던스(reflected impedance)가 시스템에 주는 영향을 분석하고, 그 검출 방법을 제안하였다. 반사 임피던스는 송신기와 결합하는 수신기가 어떠한 특성을 가지는지를 나타내는 중요한 지표가 되며, 전송 효율에 큰 영향을 주게 된다. 반사 임피던스를 검출하기 위해서 주파수에 따른 송신기에 흐르는 전류의 변화를 분석하는 검출 방법을 제안하였다. 본 논문에서 제시한 설계 방법에 따라 LF 대역에서 동작하는 무선 송/수신시스템을 설계하고, 수신기의 반사 임피던스의 변화를 검출하였다. 측정 결과, 제안한 검출 방법이 반사 임피던스를 정확하게 측정할 수 있음을 확인하였다. 실제 배터리에 적용하여 absorption mode에서 시간에 따라 증가하는 부하 임피던스로 인한 효율 감소를 보정할 수 있음을 실험을 통해 검증하였다. 또한, 금속 인식 시스템도 구현하여 제안한 측정법의 유용성을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1744-1746
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• 1996

Surface impedance boundary condition(SIBC) concepts are introduced into the finite-difference time-domain(FDTD) method. Lossy conductors are replaced by surface impedance boundary computations reducing the soluton space and producing significant computational savings. Specifically, a surface impedance boundary condition is developed to reduce a lossy dielectric half-space. Since Maxwell's eqations are solved directly, the reflected and transmitted pulse amplitude demonstrate how the reflection and transmision coefficient determine reflected wave amplitude. In this paper, two implementations of reflection coefficient are presented. One implementation is a standard FDTD technique and the other is a FDTD using surface impedence boundary condition(FDTD-SIBC) that are applicabIe over a very large frequency bandwidth. Particulary, an efficient way to transform the time domain results to frequency domain is presented. Thus, frequency domain results are presented in one dimension and are compared with exact results.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.423-430
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• 2002

A feasibility of a trial test method was evaluated analytically, in which the elastic modulus of a soil deposit was tried to estimate by analyzing dynamic signals measured during conducting the SPT. If there existed a reliable relationship between the impedance ratio of a rod to a soil and the amplitude ratio of a reflected to an incident wave signal at the tip of steel rod contacting the soil surface, it was expected that one could determine the impedance of soil, and then roughly estimate the elastic modulus from the impedance. For a simple rod-soil system, the existence of the relevant relationship was verified in this study by analyzing computed wave signals propagating up and down through the rod. On the basis of these results, thus, a potential of the test method to practical applications could be seen. However, apparent theoretical shortcomings possessed in this approach were also realized since the soil part had an unconfined contact area where contacted with the rod. Therefore, it was concluded that further studies needed to be conducted, in which the reliable theoretical relationship between the impedance and the amplitude ratio as well as the effective contacting soil area contributing to wave reflection should be justified.

• 반도체디스플레이기술학회지
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• 제21권2호
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• pp.32-37
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• 2022

As semiconductors become finer, equipment must perform precise and accurate processes to achieve the desired wafer fabrication requirement. Radio frequency power delivery system in plasma system plays a critical role to generate the plasma, and the role of impedance matching unit is critical to terminate the reflected radio frequency power by modifying the impedance of the matching network in the plasma equipment. Impedance matching unit contains one fixed inductor and two variable vacuum capacitors whose positions are controlled two step motors. Controlling the amount of vacuum variable capacitor should be made as soon as possible when the mismatched impedance is detected. In this paper, we present the impedance matching algorithm using the phase sensor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1985년도 하계학술회의논문집
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• pp.224-227
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• 1985

During operation of an RF glow discharge system, it can be observed that the reflected power tends to increase in small value, due to changes in the impedance of the system. This problem can be relieved by adding an automatic impedance matching circuit to the system. This paper presents a detailed method of automatically matching the input impedance of a 50 ohm transmission line to an RF glow discharge system at 13.56 MHZ.

• 대한전기학회논문지
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• 제35권12호
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• pp.560-566
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• 1986

In the design of an RF discharge system, the electrical equivalence of the gas discharge must be known. With this knowledge, one can design a suitable matching network for a maximum power transfer from the RF generator into the discharge. For this purpose, an experiment has been conducted in which the electrical impedance (conductance and capacitance) was determined as a function of power. In parallel with this, a detailed theoretical analysis has been done and the results are in accord with those of our experiment. Design equations are also given for a simple matching network, and a design example is presented to demonstrate its application. During the actual operation of an RF discharge system, however, it has been often observed that the reflected power tends to vary in small values due to the changes in the impedance of the system. This problem can be relieved by adding an automatic impedance matching circuit to the system and this paper presents such an automatic impedance matching network.