• Journal of Power Electronics
• /
• v.9 no.2
• /
• pp.164-172
• /
• 2009

Recently, 2-dimensional flat light sources have been attracting much attention for its use in LCD backlight applications because of its high luminous efficiency and uniformity. A long-gap discharge, mercury-tree flat fluorescent lamp has been developed, which shows a high brightness ($>5000\;cd/m^2$) and high luminous efficacy (60 lm/W). Additionally, it has a wide operating margin and stable driving condition with the aid of an auxiliary electrode. For driving the lamp, a narrow pulse power to maintain the glow discharge state is required. Since there has been no research for this kind of lamp driving, this paper proposes a newly developed short-pulse, high-voltage lamp-driving scheme. The proposed lamp system uses a ballast with a coupled-inductor in order to raise the short pulse voltage up to the lamp ignition level and to obtain energy-recovery action during the glow discharge mode. The operation principles are presented and also the system performances such as the lighting efficiency, spatial and angular uniformities are evaluated by hardware experiments. The results show that the proposed lighting system is a good candidate for the next-generation of LCD backlight systems.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.2
• /
• pp.688-698
• /
• 2018

Quasi Z-Source Multilevel Inverter (QZMLI) topology has attracted grid connected Photovoltaic (PV) systems in recent days. So there is a remarkable research thrust in switching techniques and control strategies of QZMLI. This paper presents the mathematical analysis of Phase shift- Pulse Width Amplitude Modulation (PS-PWAM) for QZMLI and emphasizes on the advantages of the technique. The proposed technique uses the maximum and minimum envelopes of the reference waves for generation of pulses and proportion of it to generate shoot-through pulses. Hence, it results in maximum utilization of input voltage, lesser switching loss, reduced Total Harmonic Distortion (THD) of the output voltage, reduced inductor current ripple and capacitor voltage ripple. Due to these qualities, the QZMLI with PS-PWAM emerges to be the best suitable for PV based grid connected applications compared to Phase shift-Pulse Width Modulation (PS-PWM). The detailed math analysis of the proposed technique has been disclosed. Simulation has been performed for the proposed technique using MATLAB/Simulink. A prototype has been built to validate the results for which the pulses were generated using FPGA /SPARTAN 3E.

• The Journal of the Society of Korean Medicine Diagnostics
• /
• v.9 no.2
• /
• pp.57-71
• /
• 2005

Background and purpose: Maek Kyoung(脈經) is a book written, compiled, and edited by Wang Hui circa 3 A.D. This book is the first technical book devoted to the diagnostics. These are very important data but never make a special study and translate. so I hope this treatise can be great help to understand diagnosis study. Methods: Maek Kyoung(脈經) consists of ten volumes, and the third volume consists of the five chapters, including inter-generation and inter-restriction of the five viscera and the six entrails and prognosis of diseases. This treatise is made up of principal, notes, study and conclusion, we tried to make a translation faithful to the original. Results and Conclusion: Chapter 5 refers to three things. The first is relation between kidney and urinary bladder, the second is ordinary and extraordinary pulse condition of kidney, and the third is how to treat diseases related to kidney.

• Journal of Power Electronics
• /
• v.15 no.2
• /
• pp.299-308
• /
• 2015

This study proposes four novel pulse width modulation (PWM) shoot-through control methods for impedance source (IS) galvanically isolated DC-DC converters. These methods are derived from a PWM control method with shifted shoot-through introduced by the authors in 2012. In contrast to the baseline solution, where the shoot-through states are generated by the simultaneous conduction of all transistors in the inverter bridge, our new approach is based on the shoot-through generation by one inverter leg. The idea is to increase the number of soft-switched transients and, therefore, decrease the dynamic losses of the front-end inverter. All the proposed approaches are experimentally verified through an insulated-gate bipolar transistor-based IS DC-DC converter. Conclusions are drawn in accordance with the results of the switching loss analysis.

• Progress in Superconductivity and Cryogenics
• /
• v.9 no.3
• /
• pp.26-31
• /
• 2007

In recent years. YBCO coated conductor (CC) called as second generation HTS (high temperature superconducting) wire has been developed as a suitable material for resistive superconducting fault current limiter (SFCL). For designing the SFCL. the required length of superconducting wire is inverse proportional to the maximum temperature reached when a fault occurs. Since the required length strongly affects a manufacturing cost, it is the most important parameter to determine the maximum temperature reached. It is necessary to observe the repetitive over-current characteristics of HTS wire. This paper attempts to measure the variation of critical current of YBCO CC after repetitive over-current pulse. No degradation of the critical current of CC sample was observed by applying 100 times over-current pulse which makes temperature above 400 K after 100ms. This study can be useful in designing optimally resistive SFCL employing YBCO CC. The maximum permissible temperature can be set to 400K. so wire length could be reduced by 30% compared in case of 300K-criterion.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2003.10a
• /
• pp.381-385
• /
• 2003

This paper presents the fabrication possibility of the micro actuator which uses a micro-thermal bubble, generated by a micro-heater under pulse heating. The micro-actuator is consist of three plate. The lower plate includes the channel and chamber are fabricated on high processability silicon wafer by the DRIE(Deep Reactive ion Etching) process. The middle plate includes the chamber and diaphragm, and the upper plate is the micro-heater. The micro-heater designed non-uniform width and results in periodic generation of stable single bubbles in D.I water. The single bubble appears precisely on the narrow part of the micro-heater and control is recorded.

• Proceedings of the KIEE Conference
• /
• 2006.04b
• /
• pp.270-274
• /
• 2006

This paper proposes a Chaos Pulse Width Modulation(CPWM) technique. For generating the chaotic numbers by chaos phenomenon, chaos area $\lambda$=0.99 in bifurcation tree of the proposed double tent mapping is used. A micro-controller is used for the generation of chaos numbers and triangular carrier with chaotic frequency is obtained through the process of frequency modulation according to the generated chaos numbers. The experiments are executed with the 1.5kw induction motor coupled with a 2.5A load. The experimental results show that the voltage / current spectra are spread to a chaotic range, and the switching noise of motor is reduced by the proposed method compared to the fixed frequency PWM method.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.7 no.4 s.19
• /
• pp.91-99
• /
• 2004

Laser materials for eyesafe wavelength generation and Q-switching crystals for short pulse operation were studied and compared with each other. Er,Yb:phosphate glass as a laser material and $Co^{2+}:MgA1_2O_4$ as a saturable absorber were found to be an effective pair for a compact, light-weight passively Q-switched eyesafe laser operation. Simplified rate equation was used to estimate pulse parameters of the diode-pumped passively Q-switched laser.

• Journal of information and communication convergence engineering
• /
• v.6 no.4
• /
• pp.411-416
• /
• 2008

When compose magnetic field curer by belt and band style and need by magnetic field ripple last month, produce self-discipline roof. Bred in muscle disease (lumbago, backbone disease, corpulence) back. Result that study, manufactured various variableness band style - magnetic field probe firstly. Can establish self-discipline treatment pulse price by disease secondly. Could seek correct variableness band punishment, - magnetic field probe relationship implementation and property in waist, and so on, shoulder, neck, arm, leg, ankle, wrist etc. by third. Could find variableness band style energy value that need in-magnetic field Probe's treatment by fourth. This research could design pulse of self-discipline in band form and apply each according to disease.

• Journal of Power Electronics
• /
• v.16 no.4
• /
• pp.1316-1323
• /
• 2016

Multilevel inverters (MLIs) have been preferred over conventional two-level inverters due to their inherent properties such as reduced harmonic distortion, lower electromagnetic interference, minimal common mode voltage, ability to synthesize medium/high voltage from low voltage sources, etc. On the other hand, they suffer from an increased number of switching devices, complex gate pulse generation, etc. This paper develops an ingenious symmetrical MLI topology, which consumes lesser component count. The proposed level dependent sources concoction multilevel inverter (LDSCMLI) is basically a multilevel dc link MLI (MLDCMLI), which first synthesizes a stepped dc link voltage using a sources concoction module and then realizes the ac waveform through a conventional H-bridge. Seven level and eleven level versions of the proposed topology are simulated in MATLAB r2010b and prototypes are constructed to validate the performance. The proposed topology requires lesser components compared to recent component reduced MLI topologies and the classical topologies. In addition, it requires fewer carrier signals and gate driver circuits.