• Journal of Power Electronics
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• 제10권4호
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• pp.382-387
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• 2010

This paper presents a novel design method for determining the PID gains of a speed controller for a servo system compensating variations in bandwidth at a low speed. The variations in bandwidth of a speed controller are measured at a low speed and the relationship between the bandwidth and the damping ratio are verified by determining the location of the closed loop pole. The proposed algorithm uses the z-transform of a plant and speed controller and applies the time-varying sampling method for determining the PID gains of the speed controller at low speed. The magnitude and the phase condition are considered for finding a suitable control gain. The usefulness and effectiveness of the proposed method is demonstrated through experimental results such as low speed control and robust disturbance responses.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.217-218
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• 2006

We propose a method for improving the performance of the Amplitude Shift Keying (ASK) system using a fuzzy logic system for automatically tuning the bandwidth of low pass filter. Instead of a fixed bandwidth of a low pass filter of receiver, the fuzzy logic system is used to automatically adjust the bandwidth. The inputs to the fuzzy logic system are the error and change of error, and output is a bandwidth. Simulation results showed that the proposed system improves considerably on the performance of the fixed bandwidth.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 추계종합학술대회
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• pp.521-524
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• 2005

본 논문에서는 밀리미터파 대역에서 Giga-bit 모뎀을 위한 BASK 시스템의 성능개선을 위하여 수신단 low pass filter의 bandwidth를 자동으로 조절하는 방식을 제안하였다. 제안한 방식은 counter의 remainder 와 remainder의 합을 이용한 퍼지 논리 시스템으로 low pass filter의 bandwidth를 자동적으로 조절한다. 제안한 방식의 유용성을 BER 에 대한 시뮬레이션을 통하여 확인하였다.

• 제어로봇시스템학회논문지
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• 제13권5호
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• pp.462-466
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• 2007

This paper proposes an automatic bandwidth control method for the performance improvement of Binary Amplitude Shift Keying (BASK) system for Giga-Bit Modem in millimeter band. In order to improve the performance of the BASK system with a fixed bandwidth, the proposed method is to adjust a bandwidth of low pass filter in receiver using the fuzzy system. The BASK system consists of a high speed shutter of the transmitter and a counter and a repeater of receiver. The repeater consists of four stage converters, and a converter is constructed with a low pass filter and a limiter. The inputs to the fuzzy system are the reminder and integral of remainder of counter, and output is a bandwidth. We used a Viterbi algorithm to find the optimum detection from the output of the counter. Simulation results showed that the proposed system improves the performance compared to the fixed bandwidth.

• Journal of information and communication convergence engineering
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• 제3권1호
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• pp.18-22
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• 2005

This paper presents the analog adaptive phase-locked loop (PLL) architecture with a new adaptive bandwidth controller to reduce locking time and minimize jitter in PLL output for wireless communication. It adaptively controls the loop bandwidth according to the locking status. When the phase error is large, the PLL increases the loop bandwidth and reduces locking time. When the phase error is small, the PLL decreases the loop bandwidth and minimizes output jitters. The adaptive bandwidth control is implemented by controlling charge pump current depending on the locking status. A 1.28-GHz CMOS phase-locked loop with adaptive bandwidth control is designed with 0.35 $mu$m CMOS technology. It is simulated by HSPICE and achieves the primary reference sidebands at the output of the VCO are approximately -80dBc.

• IEIE Transactions on Smart Processing and Computing
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• 제5권5호
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• pp.303-309
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• 2016

This paper presents a channel-adaptive rate control algorithm for low delay video coding. The main goal of the proposed method is to adaptively use the unknown available channel bandwidth while reducing the end-to-end delay between encoder and decoder. The key idea of the proposed algorithm is for the status of the encoder buffer to indirectly reflect the mismatch between the available channel bandwidth and the generated bitrate. Hence, the proposed method fully utilizes the unknown available channel bandwidth by monitoring the encoder buffer status. Simulation results show that although the target bitrate mismatches the available channel bandwidth, the encoder efficiently adapts the given available bandwidth to improve the peak signal-to-noise ratio.

• Journal of Power Electronics
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• 제18권6호
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• pp.1760-1770
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• 2018

This paper presents a control bandwidth extension method for inverters with a low carrier ratio. The bandwidth is extended at the price of decreasing the phase margin. Then the phase margin is compensated by introducing an extra leading angle into an inverse Park transformation. The model of the controller with the proposed method is established. The magnitude and phase characteristics are also analyzed. Then the influence on system stability when the leading angle is introduced is analyzed. The proposed method is applied to design an inverter controller with both a large bandwidth and a desired phase margin, and the experimental results verify that the controller performs well in the steady-state and in terms of transient response.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 추계학술대회 논문집
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• pp.33-34
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• 2016

This paper presents a load sharing method based on the low bandwidth communication (LBC) applied to a DC microgrid in order to balance the state of charge (SOC) of the battery units connected in parallel to the common bus. In this method, SOC of each battery unit is transferred to each other through LBC to calculate average SOC value. After that, droop coefficients of battery units are adjusted according to the difference between SOC of each unit and average SOC value of all batteries in the system. The proposed method can effectively balance the SOC of battery units in charging and discharging duration with a simple low bandwidth communication system.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권4호
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• pp.178-184
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• 2005

In this paper, using diplexer structure and varactor diode controlled by reverse bias voltage for diplexer switch gives possibilities to improve isolation and current characteristics. 1 have newly designed switch with high isolation by application varactor diode corresponding to capacitor of diplexer. The low-pass filter for proposed tunable diplexer passes the microwave signal in the bandwidth for wireless cellular network systems and high-pass filter passes it in the bandwidth for wireless personal communication services (PCS) network systems. As the capacitance of the low-pass filter increases, the cut-off frequency can be moved to low frequency, so that the switch is on state in cellular bandwidth and off state in the PCS bandwidth, in contrast to, as the capacitance for attenuation characteristic of high-pass filter increases, it can be moved to high frequency, so that the switch is off state and on state in the cellular bandwidth. it is possible to improve isolation and current consumption characteristics by application diplexer design methods and varactor diode. 1 expect that the tunable diplexer circuit and design methods should be able to find applications on MMIC and low temperature copired ceramic (LTCC).

• 정보과학회 논문지
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• 제45권1호
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• pp.86-93
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• 2018

다수의 클라이언트가 대역폭을 공유해 스트리밍 서비스를 받는 경우 HTTP 적응적 스트리밍(HTTP Adaptive Streaming)은 세그먼트 요청의 ON-OFF 패턴으로 인해 대역폭을 부정확하게 측정하는 문제가 있다. ON-OFF 패턴으로 인한 문제를 해결하기 위해 제안된 PANDA (Probe AND Adapt)는 목표 대역폭을 증가시키면서 요청할 세그먼트의 품질을 결정한다. 하지만 목표 대역폭을 고정된 양만큼 증가시키기 때문에 대역폭 활용도가 낮고 대역폭 변화에 느리게 반응하는 문제가 있다. 본 논문에서는 PANDA의 낮은 대역폭 활용도와 느린 반응성을 개선하기 위한 비디오 품질 조절 기법을 제안한다. 제안하는 기법은 세그먼트 다운로드 시간과 요청 간격을 비교해 대역폭 활용도를 판단한 후 대역폭 활용도에 따라 목표 대역폭을 증가시키는 양을 조절한다. 실험을 통하여 제안하는 기법이 대역폭을 충분히 활용하고 대역폭 변화에 빠르게 반응하는 것을 확인하였다.