• Journal of Power Electronics
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• v.13 no.1
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• pp.113-121
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• 2013

This paper introduces a simple core loss calculation method for output filter inductor in pulse width modulation (PWM) DC-AC inverter. Amorphous C-core (AMCC-320) is used to analyze the core loss. In order to measure core loss of the output filter inductor and validate the proposed method, a single-phase half-bridge inverter and a calorimeter are used. By changing switching frequency and modulation index (MI) of the inverter, core loss of the AMCC-320 is measured with the lab-made calorimeter and the results are compared with calculated core loss. The proposed method can be easily extended to other core loss calculation of various converters.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2237-2239
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• 1998

A limitation is assumed that In this paper, a generalized method is proposed to extract a period of a motion of on object. To detect a periodic motion, we put restrictions on a stationary camera and on a motion of an object. We ca derive the necessary and sufficient condition that an image sequence consists of the projection of the periodic motion by the affine transformation that is a reasonally good approach to the perspective projection. The difficulty of detecting its periodic motion is to select its have period in sequence and to define its width.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.197-199
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• 2005

The Cold cathode fluorescent lamp (CCFL) are widely used to illuminate the liquid crystal display(LCD). Ballasts are required for CCFL because the lamp need high starting voltage and behave negative dynamic resistant characteristics in the desired region of operation. Dimming methods of CCFL are used to pulse frequency modulation(PFM) or pulse width modulation(PWM). In this paper, CCFL driving and control circuit is designed by half-bridge type series and parallel resonant inverter that variable frequency modulation method to control the output voltage current. The validity of this study is confirmed from the simulation and experimental results.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.215-218
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• 2001

A pulsed Nd:YAG laser is used widely for materials processing and medical instrument. It's very important to control the laser energy density in those fields using a pulsed Nd:YAG laser. A pulse repetition rate and a pulse width are regarded as the most dominant factors to control the energy density of laser beam. In this paper, the alternating charge and discharge system was designed to adjust a pulse repetition rate. This system is controlled by microprocessor and allows to frequence an expensive condenser for high frequency to cheap one for low frequency. In addtion, The microcontroller monitors the flow of cooling water, short circuit, and miss firing and so on. We designed Nd:YAG laser firmware with smart microcontroller, and want to explain general matters about the firmware from now.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.2
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• pp.87-97
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• 2013

Negative bias temperature instability (NBTI) and positive bias temperature instability (PBTI) are critical circuit reliability issues in highly scaled CMOS technologies. In this paper, we analyze the impacts of NBTI and PBTI on SRAM $V_{MIN}$, and present a design solution for mitigating the impact of NBTI and PBTI on SRAM $V_{MIN}$. Two different types of SRAM $V_{MIN}$ (SNM-limited $V_{MIN}$ and time-limited $V_{MIN}$) are explained. Simulation results show that SNM-limited $V_{MIN}$ is more sensitive to NBTI while time-limited $V_{MIN}$ is more prone to suffer from PBTI effect. The proposed NBTI/PBTI-aware control of wordline pulse width and woldline voltage improves cell stability, and mitigates the $V_{MIN}$ degradation induced by NBTI/PBTI.

• The Korean Journal of Ceramics
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• v.5 no.2
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• pp.110-114
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• 1999

NOx sensing properties of $Ba_2WO_5$ were investigated by varying the sintering temperature in an effort to study the effects of the neck-width on gas sensitivity. $Ba_2WO_5$ sintered at $800^{\circ}C$, which exhibits neck-controlled conduction provides highest sensitivity of 47 and 29 at $500^{\circ}C$ to NO and $NO_2$, respectively. The samples sintered beyond $800^{\circ}C$ show sintering temperature-independent gas sensitivity. This may be because the grain boundary control is dominant at lower sintering temperatures and open neck control is dominant at higher sintering temperatures than $800{\circ}C$. The NOx sensing mechanism of $Ba_2WO_5$ was briefly discussed.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.6
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• pp.73-76
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• 2004

This study was conducted to investigate the growth responses of Polystichum lepidocaulon as influenced by 4 different shadings(Control, 50%, 70%, 90%). Under 50 or 70% shading, plant height, stipe length, blade length, blade width, and number of spores increased compared with the other shadings, except the number of frond and shoots. The plants grown under control was shown as smaller with more yellowish green leaf color, and under 90% shading the growth was slightly inferior to those under the 50 or 70% shading. Fresh weight and segment area of frond was better in increased shade levels, but they decreased in under 90% shading. Dry weight and segment thickness decreased as shading increased. Chlorophyll contents increased in proportion to lowered light intensity. Thus, 50 or 70% shading of Polystichum lepidocaulon seemed to maintain the highest growth.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.521-524
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• 2005

We propose a method for improving the performance of BASK system using the automatic band width control of low pass filter of receive. Instead of a fixed bandwidth, proposed method is used to the fuzzy logic system. The inputs of fuzzy logic system are remainder and integral of remainder, and the output is bandwidth of low pass filter. The efficacy of the proposed method is verified by means of simulation.

• Journal of Power Electronics
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• v.5 no.3
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• pp.190-197
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• 2005

This paper presents a technique to reduce the low frequency ripple voltage of the dc output in a BIFRED converter with a small-sized energy storage capacitor. The proposed pulse width control method can be effectively used to suppress the low frequency ripple appeared in the dc output and still maintains generally good performance such as low THD of input line current and a high power factor. Using the small-sized energy storage capacitor, it has better merits of low cost and smaller size than a conventional BIFRED converter. The proposed technique is illustrated its validity and effectiveness through simulations.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.372-376
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• 2001

Due to several advantages of Pulse Width Modulation(PWM) Converter, such as unity power factor operation, elimination of low-order harmonics and regeneration of motor braking energy to source, the application range of PWM Converter has been rapidly extended in industrial application. Nowadays, vector control algorithm and space vector PWM(SVPWM) method are applied to improve the performances of PWM Converter, but vector control algorithm and SVPWM require to use Microprocessor and other digital devices in hardware, causing costly and somewhat large dimension system. In every practical application of energy conversion equipments, the design and implementation should be carried out considering cost and performance. High performance and low cost is the best choice for energy conversion equipments. So, this paper presents the practical design method and implementation results of 3-phase PWM Converter with analog hysteresis current controller, and verifies the performances of unit power factor operation and energy regeneration operation via experimental results.