• Journal of Electrical Engineering and Technology
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• v.2 no.1
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• pp.81-88
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• 2007

This paper proposes a coupled inductor-based rectifier of a Three-Level (TL) DC/DC converter and compares the rectification methods of a TL converter. The CICDR- TL (Coupled Inductor Current Doubler Rectifier Three-Level) converter achieves ZVS (Zero Voltage Switching) for the switches in a wide load range. CDR (Current Doubler Rectifier) and CICDR Three-Level converter have low voltage and current ripple. Advantages and disadvantages of topology compared to the rectifier of bridge, center-tap, CDR, and CICDR are discussed. Experimental estimation results are obtained on a 27V, 60A DC/DC TL converter prototype for the 1.8kW, 40kHz IGBT based experimental circuit.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.609-612
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• 2001

Rogowski coil is made having no ferromagnetic material in a core. So the coil cannot be driven into saturation. This result in that Rogowski coils may be calibrated at relatively low currents. and used with confidence at very high currents. However the lowest level of current that can be measured is limited by the sensitivity of the voltage measuring instrument and system noise. Therefore. geometrical effects were investigated in order to measure high sensitivity of low level current and the significant source of error was examined as well. In the results, the source of error was associated with coil designs. i.e. shape and uniformity of coil and a geometrical location of current source inside and outside of the Rogowski coil.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.609-612
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• 2001

Rogowski coil is made having no ferromagnetic material in a core. So the coil cannot be driven into saturation. This result in that Rogowski coils may be calibrated at relatively low currents, and used with confidence at very high currents. However the lowest level of current that can be measured is limited by the sensitivity of the voltage measuring instrument and system noise. Therefore, geometrical effects were investigated in order to measure high sensitivity of low level current and the significant source of error wa examined as well. n the results, the source of error was associated with coil designs, i.e. shape and uniformity of coil and a geometrical location of current source inside and outside of the Rogowski coil.

• Journal of Electrical Engineering and Technology
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• v.5 no.2
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• pp.307-318
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• 2010

In this work, an accurate analysis of low frequency current ripple in residential fuel cell power generation systems is performed based on the proposed residential load model and its unique operation algorithm. Rather than using a constant dc voltage source, a proton exchange membrane fuel cell (PEMFC) model is implemented in this research so that a system-level analysis considering the fuel cell stack, power conditioning system (PCS), and the actual load is possible. Using the attained results, a comparative study regarding the discrepancies of low frequency current ripple between a simple resistor load and a realistic residential load is performed. The data indicate that the low frequency current ripple of the proposed residential load model is increased by more than a factor of two when compared to the low frequency current ripple of a simple resistor load under identical conditions. Theoretical analysis, simulation data, and experimental results are provided, along with a model of the load usage pattern of low frequency current ripples.

• The Journal of Internal Korean Medicine
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• v.36 no.4
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• pp.561-569
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• 2015

Objectives The purpose of this study was to improve the knowledge of the low-level laser therapy (LLLT) field and to review research reports on LLLT to understand the current situation with respect to the clinical indication and current research trends.Methods A survey was carried out on the subject of low-level laser therapy to September 2012, using the PubMed search engine. Selected literature was checked by two reviewers and was classified according to the International Classification of Diseases 10th (ICD-10) over 10 years.Results We selected 469 studies in total, of which 142 were case reports, 118 were case-controlled trials, and 209 were randomized controlled trials of LLLT. According to the ICD-10 classification of diseases, the K code and M code being the most common, 399 studies have been published in the last 10 years. This shows that the study and clinical indications of low-level laser therapy have rapidly increased over the past 10 years.Conclusions Low-level laser therapy has been used most frequently with respect to dentistry and pain and musculoskeletal disorders. Recently, interest in and research into LLLT has increased for various diseases. With the establishment of standard conditions for low-level laser therapy, supported by aggressive clinical utilization and systematic clinical research, LLLT will be a very useful treatment and a useful alternative method in many medical fields.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.929-930
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• 2006

This paper presents a direct instantaneous torque control (DITC) of Switched Reluctance Moto (SRM) with a novel 4-level converter to obtain smooth torque and dynamic performance improvement. The DITC method can reduce the high inherent torque ripple of SRM drive system, but driving efficiency and dynamic performance are somewhat low due to the slow excitation current build-up. Since the 4-level converter can obtain a addition high voltage to get fast excitation current and demagnetization current, so, it can improve dynamic performance easily. As a high performance SRM drive system with low torque ripple and high dynamic performance can be implemented. The validity of proposed method is verified by some computer simulations and comparative experiments.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.747-750
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• 2005

In this paper, we propose a new level shifter circuit for reducing power consumption. The concept of the proposed level shifter is to use capacitive coupling effect to reduce short circuit current. The power consumption of the proposed level shifter is reduced up to 50%, compared to the conventional level shifter. Especially the proposed level shifter circuit works well with low temperature poly-Si (LTPS) TFTs. It can operate on low input voltage even with low-mobility, high and widely-varying threshold voltage of LTPS TFT.

• Journal of Power Electronics
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• v.15 no.3
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• pp.652-659
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• 2015

This paper presents a new hybrid soft switching dc-dc converter with a low circulating current and high circuit efficiency. The proposed hybrid converter includes two sub-converters sharing two power switches. One is a three-level PWM converter and the other is a LLC converter. The LLC converter and the three-level converter share the lagging-leg switches and extend the zero-voltage switching (ZVS) range of the lagging-leg switches from nearly zero to full load since the LLC converter can be operated at f_sw (switching frequency) $\approx$ f_r (series resonant frequency). A passive snubber is used on the secondary side of the three-level converter to decrease the circulating current on the primary side, especially at high input voltage and full load conditions. Thus, the conduction losses due to the circulating current are reduced. The output sides of the two converters are connected in series. Energy can be transferred from the input voltage to the output load within the whole switching period. Finally, the effectiveness of the proposed converter is verified by experiments with a 1.44kW prototype circuit.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.5 s.311
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• pp.1-7
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• 2006

This paper presents experimental instruction-level current consumption model for low power microcontroller ATmega128. The accessibility of instruction for internal memory decides power consumption of the microcontroller as much as 17% of difference between access instruction and non-access instruction. The power consumption for the given program will be increased in the proportional to the ratio of memory access instruction and lower level memory access in the hierarchy. Throughout the current consumption model, the power consumption can be predicted and optimized in the direction of reducing the frequency memory access. Also, the various optimization methods are introduced in terms of software and hardware viewpoints.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.5
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• pp.388-392
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• 2012

In this paper, a sampler model for the P-type current mode control employing low pass filter is proposed. Even though the frequency response of the compensator used in a P-type current mode control employing low pass filter is similar to that of P-type compensator, the sampler model has to be obtained from the method used in PI-type current mode control. In order to show the usefulness of the proposed method, prediction results of the proposed model are compared to those from the circuit level simulator, PSIM.