• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.4
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• pp.101-112
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• 2004

In this paper, we developed a numerical analysis model by using ADI-FDTD method to analyze three-dimensional interconnect structure. We discretized maxwell's curl equation by using ADI-FDTD. Using ADI-FDTD method, a sampler circuit designed from 3.3 V CMOS technology is simplified to 3-metal line structure. Using this simplified structure, the time delay and signal distortion of complex interconnects are investigated. As results of simulation, 5∼10 ps of delay time and 0.1∼0.2 V of signal distortion are measured. As demonstrated in this paper, the full-wave analysis using ADI-FDTD exhibits a promise for accurate modeling of electromagnetic phenomena in high-speed VLSI interconnect.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.05
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• pp.38-41
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• 1993

For efficient transmission and storage of digital images, the requirements of image compression is incresing. Because the medical images contain diagnostic information small distortion has been more important factor than the low rate in such images. Generally the distortion in image is the difference of pixel values. However the image is percieved by human visual systems. So it is reasonable that human visual system characteristics be used as criteria of the image compression. In this paper, the Just Noticeable Difference curve is used as criteria of determining the homogeniety of a block and acceptibility of distortions. And Block Truncation Coding using spatial masking effect of eyes is adopted to code the blocks which contain line components. And small blocks which varies slowly can be approximated to polynomial functions successfully. We proposed the hybrid block coding scheme based on the block characteristics and human visual system characteristics. Simulation to several kinds of the medical images using this method showed that medical images can be compressed 5:1 - 10:1 without noticeable distortion.

• Korean Journal of Computational Design and Engineering
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• v.22 no.1
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• pp.70-79
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• 2017

Weft straightener is an important process to control the final quality of the fabrics. It is needed to calibrate the distorted weft after dyeing process. During various fabric treatment processes, the fabric is almost done with heat treatment through a tenter machine. At this time, weft distortion is occurred with uneven tension distribution. Traditionally, photo sensor is commonly used to detect the weft distortion but it is not applicable for special fabric types such as twill, mesh, combi, etc. In this paper, a new method for detecting the weft distortion using camera is introduced. A new weft straightener simulator is also developed to test the ability of the proposed method. It is shown that the method can be applied for various fabric types.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.4
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• pp.375-387
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• 2015

This study investigates an economic and highly efficient power-converter topology and its modulation scheme for 60 kW rapid EV charger system. The target system is a three-phase three-switch buck-type rectifier topology. A new carrier-based PWM scheme, which is characterized by simple implementation using logic gates, is introduced in this paper. This PWM scheme replaces the diode rectifier equivalent switching state with an active switching state to produce the same effective current flowing path. As a result, the distortion of input current during the polarity reversal of capacitor line voltage can be mitigated. The proposed modulation technique is confirmed through simulation verification. The proposed modulation technique and its implementation scheme can expand the operation range of the three-phase three-switch buck-type rectifier with high-quality AC input and capacitor ripple current.

• The Journal of Korean Physical Therapy
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• v.35 no.1
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• pp.31-35
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• 2023

Purpose: This study sought to identify whether fascial therapy using myofascial release (MFR) and Fascial Distortion Model (FDM) techniques affected not only the area where treatment was being given but also remote areas connected to the treatment area by fascial continuity through comparison of the pain pressure threshold (PPT). Methods: The subjects were 16 healthy normal adults in their 20s and 30s who were divided into the MFR and FDM groups before the experiment. The PPT was measured at 4 different points on the body of the subjects. C7, T7, L5, and gastrocnemius along the superficial back line (SBL) before and after the intervention. Results: Only the FDM group subjects showed a significant increase in the PPT at T7 after the intervention. (p<0.05). In addition, the FDM group demonstrated significantly increased PPT at L5 compared to the MFR group. However, neither the FDM nor the MFR group showed a meaningful change in the PPT at the remote area in the lower leg. Conclusion: These findings showed that FDM can affect PPT more and has a positive effect on the pain threshold compared to MFR. However, neither FDM nor MFR showed any effect on the PPT in a remote area.

• Journal of Power Electronics
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• v.8 no.3
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• pp.248-258
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• 2008

The Voltage Source Converter (VSC) is replacing the conventional line commutated current source converters in High Voltage DC (HVDC) transmission systems. The control of a two-level voltage source converter and its design dealt with HVDC systems and various factors such as reactive power, power factor, and harmonics distortion are discussed in detail. Simulation results are given for the two-level converter and designed control is used for bidirectional power flow. The harmonics minimization is taken by extending the 6-pulse VSC to multipulse voltage source converters. The control is also tested and simulated for a 12-pulse voltage source converter to minimize the harmonic distortion in AC currents.

• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.11-14
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• 2007

In recent years, installation of the new and renewable energy system is rapidly increasing. Because the new and renewable energy system is a practical distributed generation system to save energy resources and to keep environments clean. Conventional single-phase utility interactive inverter controls output current by using PI current controller. However, this method is insufficient to suppress harmonic current resulted from nonlinear loads in grid line. In this paper, in order to suppress periodic waveform distortion and improve THD(Total Harmonic Distortion), new type current controller added a parallel repetitive controller is proposed and then performance of the proposed controller was verified with computer simulation.

• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.130-132
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• 2007

Recently, regulation for THD(Total Harmonic Distortion) such as IEC 61000-3-2, IEEE 519 is being reinforced about a product which directly connects to AC line in order to prevent distortion of common power source in electronic equipment and electrical machinery. In order to satisfy these regulations, conventional circuits were used two-stage structure attached power factor correction circuit at ahead of converter but this method complicate the circuit and then a number of element increases thereupon the cost of production rises. In this paper, we propose a high efficiency single-stage 300W PFC flyback converter, that improved power factor and efficiency than conventional two-stage power module.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.406-410
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• 2004

Generally, a voltage difference exists between the reference and the output voltagesin a pulse width modulated (PWM) voltage source inverter (VSI). In this paper, the nonlinearity in a PWM VSI is analyzed and a new on-line estimation method in consideration of parameter variations for a permanent magnet synchronous motor (PMSM) is proposed to compensate the time varying voltage distortion.

• Journal of Power Electronics
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• v.18 no.2
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• pp.323-331
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• 2018

Buck power factor correction (PFC) converters, compared with conventional boost PFC converters, exhibit high efficiency performance in the entire range of universal line voltage. This feature has gotten more attention for eliminating the zero crossing dead angle of buck PFC rectifiers. Furthermore, bridgeless structures for the reduction of conduction losses have been proposed. The aim of this paper is to introduce a single-phase buck rectifier that simultaneously has unity power factor (PF) and bridgeless structure while operating in the continuous conduction mode (CCM). For this purpose, two auxiliary flyback converters without any active switches are applied to a bridgeless buck rectifier to eliminate the zero crossing dead angle and achieve unity power factor, low total harmonic distortion (THD) and high efficiency. The operation and design considerations of the proposed rectifier are verified on a 150W, 48V prototype using a conventional peak-current-mode control. The measurement results show that the proposed rectifier has nearly unity power factor, THD less than 7% and high efficiency.