• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.229-232
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• 2003

AC PDP의 ADS 추동 방식은 구동 방법이 간단하여 구현하기가 용이할 뿐만 아니라 가장 안정적인 구동 방식으로 널리 사용되고 있다 [1]. 그러나 ADS 구동 방식은 주사선의 수가 늘어남에 따라 어드레싱에 필요한 시간이 증가하게 되고 유지방전 구간에 할애할 시간이 상대적으로 감소하게 되어 휘도가 저하되게 되는 문제점을 갖고 있다. 이러한 문제를 해결하기 위하여 어드레싱 시간을 최소화하기 위한 고속 어드레싱 기술에 대한 연구가 계속하여 진행되고 있다 [2-10]. 본 논문에서는 고속 구동 시에 나타나는 불안정한 어드레싱으로 인한 화질의 저하문제를 해결하기 위한 개선된 ADS 구동파형을 제시한다. 초기화 구간의 Reset 파형은 어드레싱 추간의 특성에 중요한 영향을 미치게 되는데, Reset 구간에서 생성된 벽전하를 어드레싱 방전구간 동안 지속적으로 유지되게 함으로서 어드레싱 방전전압을 줄이고 안정적인 어드레싱이 유지될 수 있도록 하였다. 본 논문에서는 Priming Effect의 영향이 급격히 감소하는 80us 이후, 벽전하의 생성을 돕는 Wall Charge Acceleration Pulse를 적용함으로서 불안정한 어드레싱 문제를 해결할 수 있는 방법을 제시하였고 휘도의 불균등화로 인한 화질 저하의 문제를 해결하였다.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.911-914
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• 1992

We have investigated the micro-discharge in plasma display panel using 2 dimensional 2 fluid MHD equations. Plasma display utilizes the physical phenomena of the normal glow or abnormal glow and is considered to be able to provide the largest display area among various flat panel. 2 fluid, 2 dimensional Magneto-Hydro-Dynamic equations are applied to Computational field of 100${\times}$800${\mu}m^2$. Time varing glows and after-glows were investigated for 11 $\mu$sec. We obtained the distribution of the microscopic variables such as the density, temperature, velocity of Ne+Ar0.1% gas plasma. During the first 6$\mu$ sec, glow discharge dued to DC pulse was investigated. Time varing phenomena of after-glow was also investigated during the last 5 $\mu$set. From results, it was found that the driving efficiency of a DC Plasma Display Panel could be improved when the diffusion of ions and electrons are controlled by the pulses applied to the auxiliary anode.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.4
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• pp.113-117
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• 2007

The study was performed on the development of system in which the bead width can be controlled. In order to control the bead width, we designed the automatic seam tracking device by attaching the probe type strain gauge sensor, motor driving slide and encoder to check the moving distance, and interface card connected MCU(80Cl96KC) upside the speed controllable carriage. Seam tracking experiments were done by changing the bead width. We compared and analyzed the sampling data which were obtained by output voltage of strain gauge sensor and rotary encoder pulse every 50ms.

• Proceedings of the KOSOMBE Conference
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• v.1994 no.12
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• pp.43-46
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• 1994

A new spatial localization technique using high-order surface gradient coil (SGC) is proposed. Although the Spatial Selection with High-Order gradient (SHOT) can provide a 2-D selection with only one selective RF pulse, the high-order gradient produced by cylindrical-shape coils has not been clinically useful for clinical systems due to the large minimum selection size caused by the limited radial gradient intensity. However, by using the proposed high-order SGCs located near the imaging region, the size of volume selection can be reduced to a clinically useful 1-4 cm in diameter by applying stronger radial gradient with much less gradient driving power. A 40 cm-by-40 cm $r^{2}$ SGC has been designed and constructed, and phantom and volunteer studies have been performed. Experimental results using spatially localized MRI show good agreement to the theoretically predicted behavior.

• Journal of Biomedical Engineering Research
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• v.7 no.1
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• pp.59-66
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• 1986

A prototype ultrasound sector B-scanner has been developed where the front-end hardware refers to all the necessary circuits for transmitting the ultrasound pulses into the human body and receiving the reflected echo signals from it. The front-end hardware can generally be divided into three parts, i.e., a pulse generator for insonification, a receiver which is responsible for processing of low-level analog signals, and a steering controller for driving the mechanical sector probe whose functions and design concepts are described in this paper. The front-end hardware is implemented which incorporates the following features: improvement of the axial resolution using a circuit which reduces the ring-down time, flexibility of generating time-gain compensation curve, and adoption of a one-chip microcomputer for generating the rate pulses based on the sensor output waveforms.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.3
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• pp.153-160
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• 2018

Recent trends in high-power-density applications have highlighted the importance of designing power converters with high-frequency operation. However, conventional LLC resonant converters present limitations in terms of high-frequency driving due to switching losses during the turn-off period. Switching losses are caused by the overlap of the voltage and current during this period, and can be decreased by reducing the switch voltage. In turn, the switch voltage can be reduced through a series connection of four switches, and additional circuitry is essential for balancing the voltage of each switch. In this work, a three-level LLC resonant converter that can operate at high frequency is proposed by reducing switch losses and balancing the voltages of all switches with only one capacitor. The voltage-balancing principle of the proposed circuit can be extended to n-level converters, which further reduces the switch voltage stress. As a result, the proposed circuit is applicable to high-input applications. To confirm the validity of the proposed circuit, theoretical analysis and experimental verification results from a 350 W-rated prototype are presented.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.791-794
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• 2003

The increasing computational capability of processors is driving the need for high bandwidth links to communicate and store the information that is processed. Such links are often an important part of multi processor interconnection, processor-to-memory interfaces and Serial-network interfaces. This paper describes a 0.11-${\mu}{\textrm}{m}$ CMOS 4 Gbp s/pin 3-Level transceiver using RSL/(Rambus Signaling Logic) for high bandwidth. This system which uses a high-gain windowed integrating receiver with wide common-mode range which was designed in order to improve SNR when operating with the smaller input overdrive of 3-Level. For multi-gigabit/second application, the data rate is limited by Inter-Symbol Interference (ISI) caused by low pass effects of channel, process-limited on-chip clock frequency, and serial link distance. In order to detect the transmited 4Gbps/pin with 3-Level data sucessfully ,the receiver is designed using 3-stage sense amplifier. The proposed transceiver employes multi-level signaling (3-Level Pulse Amplitude Modulation) using clock multi phase, double data rate and Prbs patten generator. The transceiver shows data rate of 3.2 ~ 4.0 Gbps/pin with a 1GHz internal clock.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.3
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• pp.438-443
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• 2006

The probe type sensor using strain gauges was used to track a container box's seam in this paper. A strain gauge has a property which the specific resistance is changed by varying of the sectional area and length when tensile and compressive stresses are generated at the strain gauge. We designed the automatic seam tracking device by attaching the probe type strain gauge sensor, motor driving slide, encorder to check the moving distance and interface card connected MPU upside the speed controllable carriage. The folded work piece for a container box is made to examine whether the device can track the seam automatically or not. Seam tracking experiments were done by changing the carriage moving speed at 300. 400. 500. 600[mm/min] each as the voltage of side track was 2.5[V]. We compared and analyzed the sampling data which is obtained by output voltage of strain gauge sensor and rotary encorder pulse every 100 [m/s]. The welding experiments were performed by using $CO_2$ welding machine about the carriage moving speed that has good seam tracking condition in the seam tracking experiments above. And we compared the seam tracking status.

• Journal of ILASS-Korea
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• v.19 no.1
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• pp.9-14
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• 2014

Performance of DI diesel engine with high-pressure fuel injection equipment is directly related to its emission characteristics and fuel consumption. So, the electro-hydraulic injector for the common-rail injection system should be designed to meet the precise high fuel delivery control capability. Currently, most high pressure injector in use has a needle driven by the solenoid coil energy or the piezo actuator controlled by charge-discharge of output pulse current. In this study, macroscopic spray approaching method was applied under constant volume chamber to research the performance of three different injectors : solenoid, indirect-acting piezo and direct-acting piezo type for CR direct-injection. LED back illumination for Mie scattering was applied on the liquid spray visible of direct-acting piezo injector, including hydraulic-servo type solenoid and piezo-driven injectors. As main results, we found that a direct-acting piezo injector had better a spray tip penetration than hydraulic-servo injectors in spray visualization.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.276.2-278
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• 2000

In a recent years, a number of approaches have been studied, including passive, active, and hybrid mode-locking of semi-conductor lasers for short pulse generation and research has been devoted to achieve low timing-jitter operation since the timing jitter is unfavorable for system applications. Among the methods of mode locking, passive mode locking does not need external rf drives, and therefore the operation and fabrication procedures are simplified. In spite of these attractive advantages of passive mode-locked laser, it has critical drawbacks such as large timing jitter and the difficulty in synchronization with external circuits. Their inherent large timing jitter value was shown to be suppressed to certain levels by means of hybrid mode-locking technique$^{(1)}$ , where the saturable absorber section was modulated by an external signal with the cavity round trip frequency. Furthermore, the subharmonic mode-locking (SHML) technique alleviates the restrictions of high speed driving electronics. It has been demonstrated experimentally$^{(1)}$ that the hybrid subharmonic mode-locking technique has lead to significant reduction of the timing jitter. (omitted)