• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.2
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• pp.69-76
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• 2013

In this paper, electronic ballast using resonant inverter for HID lamp is designed and implemented. The proposed electronic ballast is used the soft switching technology ZVS(Zero Voltage Switching) to reduce turn-on and turn-off loss. The ignition of proposed electronic ballast is achieved by controlling a full bridge inverter which is consisted of LC filter for resonance. After ignition the ballast operates as a low frequency square wave inverter by controlling a full bridge inverter as a buck converter. After ignition at resonant frequency of $f_o$=160kHz, the switching frequency of a buck converter is consisted of 50kHz of high frequency and 170Hz of low frequency. This is for attenuating high frequency harmonics and avoiding acoustic resonance. The experimental results show that electronic ballast using resonant inverter is operated stably.

• Journal of Korea Multimedia Society
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• v.19 no.3
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• pp.567-572
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• 2016

N-screen is an emerging technology to support multimedia multicasting, content sharing and content mobility. N-screen service providers should obtain the technology that provides the highest quality content seamlessly. Distributed nature of WiMedia distributed-MAC protocol can provide full mobility support, and achieves seamless medium access method in contrast to IEEE 802.15.3. So, in this paper, WiMedia distributed-MAC protocol is adopted and an asynchronous multicast transmission (AMT) technology is proposed to enhance performance of seamless N-screen wireless service based on distributed-MAC. The ACK frame transmissions are not required for multicast transmissions. By using this property in AMT, if a device is a multicast receiver, its reserved time slots can be reserved by the other devices with 1-hop distance. Furthermore, each N-screen device broadcasts and shares the information including an order in asynchronous traffic reservations to reduce conflicts in determining the transmission order of asynchronous N-screen packets. Therefore, AMT scheme expands the number of time slots available and throughputs for multicast and asynchronous traffic reservations when comparing with the distributed-MAC standard system. N-screen communications based on distributed-MAC with the proposed AMT shows a new framework for realizing N-screen wireless service with the full content mobility.

• Journal of Power Electronics
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• v.9 no.3
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• pp.499-506
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• 2009

In this paper, the initial pole-position estimation of a surface (non-salient) permanent magnet synchronous motor is mathematically analyzed and surveyed on the basis of simulation analysis, and developed for accurate servo motor drive. This algorithm is well carried out under the full closed-loop position control without any pole sensors and is completely insensitive to any motor parameters. This estimation is based on the principle that the initial pole-position is simply calculated by the reverse trigonometric function using the two feedback currents in the full closed-loop position control. The proposed algorithm consists of the predefined reference position profile, the information of feedback currents, speed, and relative position, and the reverse trigonometric function for the initial-pole position estimation. Comparing with the existing researches, the mathematical analysis is introduced to get a more accurate initial pole-position of the surface permanent magnet motor under the closed-loop position control. It is found that the proposed algorithm can be easily applied in servo drive applications because it satisfies the following user's specifications; accuracy and moving distance.

• Journal of Power Electronics
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• v.10 no.1
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• pp.27-33
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• 2010

This paper presents a bidirectional DC-DC converter suitable for low-voltage super capacitor-based electric energy storage systems. The DC-DC converter presented here consists of a full-bridge circuit and a current-fed push-pull circuit with a high frequency (HF) transformer-link. In order to reduce the device-conduction losses due to the large current of the super capacitor as well as unnecessary ringing, synchronous rectification is employed in the super capacitor-charging mode. A wide range of voltage regulation between the battery and the super capacitor can be realized by employing a Phase-Shifting (PS) Pulse Width Modulation (PWM) scheme in the full-bridge circuit for the super capacitor charging mode as well as the overlapping PWM scheme of the gate signals to the active power devices in the push-pull circuit for the super capacitor discharging mode. Essential performance of the bidirectional DC-DC converter is demonstrated with simulation and experiment results, and the practical effectiveness of the DC-DC converter is discussed.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.395-396
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• 2008

There is difficulty in predicting the program efficiency of NOR type nonvolatile memory device adopting channel hot electron injection (CHEI) as program operation mechanism accurately since MOSFET on SOI has floating body. In this study, the dependence of program efficiency for SOI nonvolatile memory device of 200 nm channel length on SOI depletion conditions, partial depletion and full depletion, was quantitatively investigated with the aid of numerical device simulation [1].

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.856-859
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• 2002

This paper proposes a high-performance VLSl architecture using distributed arithmetic for higher-order FIR filters with complex coefficients. For the purpose of realizing high sampling rate with small latency in high-order filters, we apply distributed arithmetic[1］. Moreover, in order to decrease drastically the power dissipation, the structure applying not ROM's but optimum function circuits which we have previously proposed, is utilized［2]［3］. However, this structure increases in the number of adders as compared to the conventional structure applying ROM's. In order to realize a more effective method for further higher-order filter, we propose newly an implementation applying two methods which have large effects on the unit using the adders. First , we propose an implementation applying SFAs(Serial Full Adders) and SFSs(Serial Full Subtractors). Second, we propose a structure applying proposed 4-2 adders. Finally, it is shown that the proposed architecture is an effective way to realize low power dissipation and small latency while the sampling rate is kept constant for further higher-order filters with complex coefficients.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.1 s.307
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• pp.1-8
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• 2006

This paper presents a fast full search algorithm for motion estimation applicable to multiple reference images. The proposed method is an extended version of the rate constrained successive elimination algorithm (RSEA) for multiple reference frame applications. We will show that motion estimation for the reference images temporally preceding the first reference image can be less intensive in computation compared with that for the first reference image. for computational reduction, we will drive a new condition to lead the smaller number of candidate blocks for the best matched block. Simulation results explain that our method reduces computation complexity although it has the same quality as RSEA.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.570-573
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• 2003

Wheels for passenger car support the car weight with tires. and they transmit rolling and braking power into the ground. Whittliing away at wheel weight is more effective to boost fuel economy that lighting vehicle body structure. A shape of hole in disk is optimized for minimizing the weight of steel wheel. Pro/ENGINEER program is used for formulating the design model. and ANSYS package is selected for analyzing the design model. It has difficulties 10 interface these commercial software directly. For combining both programs. response surface methodology is applied to construct approximation functions for maximum stresses and maximum displacements are obtained by full factorial design of five levels. This steel wheel is modeled in 14-inch diameter of rim. and wide parameter of hole in disk is only selected as design variable for reducing the weight of steel wheel. PLBA(Pshenichny·Lim-Belegundu_arora) algorithm. which uses the second-order information in the direction finding problem and uses the active set strategy. is used for solving optimization problems.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.5
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• pp.430-442
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• 2013

This paper presents a fast multi-reference frame integer motion estimator for H.264/AVC. The proposed system uses the previously proposed fast multi-reference frame algorithm. The previously proposed algorithm executes a full search area motion estimation in reference frames 0 and 1. After that, the search areas of motion estimation in reference frames 2, 3 and 4 are minimized by a linear relationship between the motion vector and the distances from the current frame to the reference frames. For hardware implementation, the modified algorithm optimizes the search area, reduces the overlapping search area and modifies a division equation. Because the search area is reduced, the amount of computation is reduced by 58.7%. In experimental results, the modified algorithm shows an increase of bit-rate in 0.36% when compared with the five reference frame standard. The pipeline structure and the memory controller are also adopted for real-time video encoding. The proposed system is implemented using 0.13 um CMOS technology, and the gate count is 1089K with 6.50 KB of internal SRAM. It can encode a Full HD video ($1920{\times}1080P@30Hz$) in real-time at a 135 MHz clock speed with 5 reference frames.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.57-63
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• 2015

There are increasing demands for the transmission of high speed and non-compressed video informations. The video data usually compressed before transmission for reducing the data. And the received data uncompressed at a receiver, consequently the processing delay is unavoided. In this paper, we implement a 60 GHz band wireless transmission system for real time multimedia contents transmission, and successfully transmit the full HD class uncompressed video information at 4 Gbps with 20 m apart. Hence the non-compressed video data from a remote camera or a smart phone can be transmitted and displayed in a large screen in real time via the developed transceiver system.