• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.381-383
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• 2007

Charge-pump high voltage inverter for Plasma backlight with CIM(Current Injection Method) is proposed in this paper. Adoption of ERC is a new attempt in high voltage inverter so that it is not only energy recovery but also improvement of discharge stability and system unstability which is interrupted by noise. Using a charge-pump technique enables low voltage switches to be usable, the cost can be reduce. CIM is adopted to achieve high speed energy recovery in proposed circuit. Operations of the proposed circuit are analyzed for each mode. The proposed circuit is verified to be applicable on a 32 inch plasma backlight panel by experimental results.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.367-368
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• 2017

본 논문에서는 영전류 모드로 진입한 zero voltage transition(ZVT) interleaved bi-direction low voltage DC-DC converter(IB-LDC)의 도통 손실을 최소화하기 위한 위상 제어가 제안된다. IB-LDC의 출력단 배터리가 완충되어 영전류 모드로 진입하면 IB-LDC의 입 출력 평균 전류는 0[A]로 감소하지만 보조 회로 전류는 기존의 설계 값에 의해 감소하지 않아 지속적인 도통 손실을 일으킨다. 따라서 본 논문에서는 영전류 모드로 진입한 IB-LDC의 보조 회로에 ZVT 조건을 만족시키는 공진 전류만 흐르도록 하여 도통 손실을 최소화하는 위상 제어를 제안하였다. 또한 PSIM simulation 및 실험을 통해 증명하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.409-411
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• 2005

이동 단말기 또는 센서 등이 사용하는 무선 통신에서는 통신에 소모되는 전력을 줄이는 문제가 중요시된다. 따라서 802.11 무선 LAN의 PSM과 같이, 대부분의 무선 통신 기술들은 일시적으로 NIC를 꺼서 전력소모를 줄이는 Sleep 모드 기능을 제공하고 있다. 그러나 Sleep 기간 동안 해당 단말로 보내져야할 트래픽이 다양한 형태로 발생할 수 있다는 점을 깊이 고려하지 않고 Sleep 모드의 동작을 정의하였으며, 그 결과 예상하지 못한 현상이 발생할 가능성이 상존한다. 본 연구에서는 이와 같은 현상의 예로서, 802.11의 PSM 노드에 발생할 수 있는 성능 반전과 에너지 소모를 통한 서비스 거부 공격을 제시한다. 또한 이와 같은 비정상적인 현상을 방지하는 방법으로서 기존의 Sleep을 폐쇄적(Closed) Sleep과 개방적(Open) Sleep으로 세분할 것을 제안한다.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.30-33
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• 2001

Advantages of switched reluctance motor(SRM) drives make it an attractive candidate for replacing adjustable speed ac and do drives in both industrial and consumer applications. Furthermore, a simple, low cost and robust SRM drive can be efficiently operatied ill the hostile environment of an automobile. In this paper, novel topology for fast response of various load is proposed. Proposed topology adapts anti-windup PI controller at increasing speed referense and activate braking mode at decreasing speed and forward load, Experiental results show that proposed topology have fast response charecteristics at increasing and decreasing speed reference.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.529-532
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• 2003

In this paper, the discharge characteristics of silent discharge chamber with 2mm and 3mm gap spacings were investigated. Dielectric of $Al_2O_3$ was embedded in the cylindrical type of discharge chamber. It was known that V-I and P-V characteristics depend strongly on the charge transportation characteristics, and in the low frequency silent discharge mode of operation, discharge voltage was always sustained to Vd, irrespective of applied voltage.

• ETRI Journal
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• v.27 no.5
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• pp.473-483
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• 2005

In this paper, we propose two LC voltage-controlled oscillators (VCOs) that improve both phase noise and tuning range. With both 1/f induced low-frequency noise and low-frequency thermal noise around DC or around harmonics suppressed significantly by the employment of a current-current negative feedback (CCNF) loop, the phase noise in the CCNF LC VCO has been improved by about 10 dB at 6 MHz offset compared to the conventional LC VCO. The phase noise of the CCNF VCO was measured as -112 dBc/Hz at 6 MHz offset from 5.5 GHz carrier frequency. Also, we present a bandwidth-enhanced LC VCO whose tuning range has been increased about 250 % by connecting the varactor to the bases of the cross-coupled pair. The phase noise of the bandwidth-enhanced LC-tank VCO has been improved by about 6 dB at 6 MHz offset compared to the conventional LC VCO. The phase noise reduction has been achieved because the DC-decoupling capacitor Cc prevents the output common-mode level from modulating the varactor bias point, and the signal power increases in the LC-tank resonator. The bandwidth-enhanced LC VCO represents a 12 % bandwidth and phase noise of -108 dBc/Hz at 6 MHz offset.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.3
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• pp.353-364
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• 2007

In this paper, a nonlinear finite element analysis program NUCAS, which has been developed for assessment of ultimate pressure capacity and failure mode for nuclear containment building is described. Degenerated shell element with assumed strain method and low-order solid element with enhanced assumed strain method is adapted to microscopic material and elasto-plastic material model, respectively. Finally, the performance of the developed program is tested and demonstrated with several examples. From the numerical tests, the present results show a good agreement with experimental data or other numerical results.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.3
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• pp.91-98
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• 2015

There is a new evolution in technological advancement taking place called the Internet of Things (IoT), The IoT enables physical world objects in our surrounding to be connected to the Internet. ISM (Industrial Scientific Medical) band that is 2.4GHz band authorized free of charge is being widely used for smart devices. Accordingly studies have been continuously conducted on the possibility of coexistence among nodes using ISM band. In particular, the interference of IEEE 802.11b based Wi-Fi devices using overlapping channel during communication among IEEE 802.15.4 based wireless sensor nodes suitable for low-power, low-speed communication using ISM band. Because serious network performance deterioration of wireless sensor networks. In this paper, we will propose an algorithm that identifies the possibility of using more accurate channels by mixing utilization of interference signal and RSSI (Received Signal Strength Indicator) Min/Max/Activity of Interference signal by wireless sensor nodes. In addition, it will verify our algorithm by using OPNET Network verification simulator.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.4A
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• pp.214-218
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• 2012

In this paper, we reported on a high performance waveguide VCO(voltage controlled oscillator) for FMCW applications. The waveguide VCO consists of a GaAs Gunn diode, a varactor diode, and two bias posts with low pass filter(LPF). The cavity is designed for fundamental mode at 47 GHz and operated at second harmonic of 94 GHz center frequency. The developed waveguide VCO has 1.095 GHz bandwidth, 590 MHz linearity with 1.69% and output power from 14.86 to 15.93 dBm. The phase noise is under -95 dBc/Hz at 1 MHz offset.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.46-49
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• 2002

Recent trends of low-temperature polycrystalline Si (LTPS) TFT technologies are presented. Characteristics of LTPS TFT processes are compared with those of a-Si TFT's. In order to compete with well-established a-Si TFT-LCD technology, LTPS process has to be as simple as possible. One of the most critical processes, recrystallization of a-Si thin films, could be the process for the differentiation of LTPS technology. Along with these technical reviews, a recent development of the 5.0-inch LTPS TFT-LCD is presented. In order to achieve high-performance display characteristics and save the power consumption, the transflective mode is adopted. The 5.0-inch display with 186 pixel-per-inch, high-resolution LCD was measured to be 10% for the reflectance and 70:1 for the contrast ratio. This display is designed for a high information content hand-held PC (HHPC) application.