• International Journal of Control, Automation, and Systems
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• 제3권2호
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• pp.217-224
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• 2005

Generally, the underwater flight vehicle (UFV) depth control system operates with the following problems: it is a multi-input multi-output (MIMO) system because the UFV contains both pitch and depth angle variables as well as multiple control planes, it requires robustness because of the possibility that it may encounter uncertainties such as parameter variations and disturbances, it requires a continuous control input because the system that has reduced power consumption and acoustic noise is more practical, and further, it has the speed dependency of controller parameters because the control forces of control planes depend on the operating speed. To solve these problems, an adaptive fuzzy sliding mode controller (AFSMC), which is based on the decomposition method using expert knowledge in the UFV depth control and utilizes a fuzzy basis function expansion (FBFE) and a proportional integral augmented sliding signal, is proposed. To verify the performance of the AFSMC, UFV depth control is performed. Simulation results show that the AFSMC solves all problems experienced in the UFV depth control system online.

• 전기전자학회논문지
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• 제18권3호
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• pp.356-361
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• 2014

This paper proposes hardware architecture of HEVC (high efficiency video coding) CABAC (context-based adaptive binary arithmetic coding) binarizer. The proposed binarizer was designed and implemented as an independent module that can be integrated into HEVC CABAC encoder. It generates each bin string of each syntax element in a single cycle. It consists of controller module, TU (truncated unary binarization) module, TR (truncated Rice binarization) module, FL (fixed length binarization) module, EGK (k-th order exp-Golomb coding) module, CALR (coeff_abs_level_remaining) module, QP Delta (cu_qp_delta_abs) module, Intra Pred (intra_chroma_pred_mode) module, Inter Pred (inter_pred_idc) module, and Part Mode (part_mode) module. The proposed binarizer was designed in Verilog HDL, and it was implemented in 45 nm technology. Its operating speed, gate count, and power consumption are 200 MHz, 1,678 gates, and 50 uW, respectively.

• Journal of Power Electronics
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• 제15권3호
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• pp.634-643
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• 2015

This paper presents a high frequency design approach for improving efficiency over a wide load range in the self-driven phase-shifted full-bridge converters for server power systems. In the proposed approach, a detailed ZVS analysis of the lagging leg switches in both the continuous conduction mode (CCM) and the discontinuous conduction mode (DCM) is presented. The optimum dead time and the determination of the appropriate operation mode are given for high efficiency according to the load conditions. Finally, the optimum operation conditions are defined to achieve a high-efficiency. A laboratory prototype operating at 80 kHz, rated 1 kW (12 V-83.3 A), is built to verify proposed theoretical analysis and evaluations. The experimental results show that the maximum efficiency is achieved as 95% and 83.5% at full load and 5% load conditions, respectively.

• Journal of Power Electronics
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• 제14권1호
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• pp.40-47
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• 2014

An average current mode control scheme that consistently offers good dynamic performance for LLC series resonant DC-to-DC converters irrespective of the changes in the operational conditions is presented in this paper. The proposed control scheme employs current feedback from the resonant tank circuit through an integrator-type compensation amplifier to improve the dynamic performance and enhance the noise immunity and reliability of the feedback controller. Design guidelines are provided for both current feedback and voltage feedback compensation. The performance of the new control scheme is demonstrated through an experimental 150 W converter operating with 340 V to 390 V input voltage to provide a 24 V output voltage.

• ETRI Journal
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• 제19권2호
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• pp.35-47
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• 1997

A power amplifier operating at 3.3 V has been developed for CDMA/AMPS dual-mode cellular phones. It consists of linear GaAs power MESFET's, a new gate bias control circuit, and an output matching circuit which prevents the drain terminal of the second MESF from generating the harmonics. The relationship between the intermodulation distortion and the spectral regrowth of the power amplifier has been investigated with gate bias by using the two-tone test method and the adjacent channel leakage power ratio (ACPR) method of CDMA signals. The dissipation power of the power amplifier with a gate bias control circuit is minimized to below 1000 mW in the range of the low power levels while satisfying the ACPR of less than -26 dBc for CDMA mode. The ACPR of the power amplifier is measured to be -33 dBc at a high output power of 26 dBm.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.839-842
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• 2004

We present a fast-switching electro-optical device based on flexoelectro-optic effect in short pitch cholesterics oriented in uniform lying helix texture. The device has two operating modes: amplitude and phase modulation mode. The amplitude modulation mode is a fast in-plane switching of the device optic axis that enables to achieve a high percent of modulation of the transmitted light intensity whereas the phase mode gives a continuous change of the refractive index and thus of the phase shift of the transmitted light. By using a small concentration of diacrylate monomer and selecting the illumination conditions we have been able to create a inhomogeneous polymeric network mostly localized at both substrate surfaces and stabilize the two switching modes.

• 한국전기전자재료학회논문지
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• 제11권11호
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• pp.975-983
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• 1998

A duplexer filter operating at 1.9 GHz band for personal communication system is designed and fabricated using $lambada$/4 TEM mode dielectric resonator. The transmitting band pass filter is designed in the type of the elliptic function band rejection filter by 3 dielectric resonators with 5 additional capacitors and 3 inductors. The receiving band pass filter is designed by 3 dielectric resonators with 5 additional capacitors which give additional series resonance. The parameters which are evaluated by design theory are practically applied to the duplexer filter construction and the simulation.

• 전기학회논문지
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• 제57권3호
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• pp.488-493
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• 2008

This paper represents a dual-mode type transmission technique for a high reliable narrow-band power line communication(PLC) modem, and its design and implementation of a system-on-chip(SoC). The proposed transmission technique is based on a Chirp modulation for the purpose of overcoming time variations of power line channel environments in the narrow-bandwidth of the frequency range of 95-145.5 kHz. The designed modem is fabricated utilizing a mixed 0.18 ${\mu}m$ CMOS technology. Especially, according to the power line channel environments the data transmission rate can be selectively changed into 2.5 kbps and 480 bps. The total hardware complexity of the implemented chip is about 50,000 gates, the power consumption is about 26mW, and the operating frequency is up to 5.12 MHz.

• International Journal of Automotive Technology
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• 제8권4호
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• pp.477-481
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• 2007

In this article we present a new, reference model based, unified strategy for engine control. Three main modes are considered: first is the driver control mode where the driver controls the engine via the pedal position; second is the dashpot mode, that is, when the driver takes his foot off the pedal; and, lastly is the idle speed control mode. These modes are unified so that seamless transitions between modes now becomes possible. The unification is achieved due to the introduction of a reference model for the engine speed whereby only the desired engine speed is different for different modes while the structure of the control system remains the same for all the modes. The scheme includes an observer that estimates unknown engine load torque. A proof of robustness with respect to unknown load disturbances both within the operating modes and during intermode transitions is given.

• 비파괴검사학회지
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• 제27권3호
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• pp.262-267
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• 2007

Detection of gas leak from a tube is a very important issue in the quality control of machines such as the heat exchanger of an air-conditioner, because leakage of operating gas directly reduces the performance of machines. The acoustic emission (AE) method is a common way to detect leak of gas, however its application under the environment of mechanical vibration is restricted since most AE detectors are very sensitive to external vibration noise. In order to overcome this problem, we propose a method based on the mode analysis of the Lamb wave. In this method, the dominant Lamb mode and its frequency are found first, and then a proper band-pass filter is used to retain only this frequency component. In this way, we could improve the SNR (signal-to-noise ratio) of AE signal generated by gas leak from the tube even under vibratory environment.