• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4A
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• pp.271-281
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• 2005

This paper for establishing the reliability of the TPC command is introduced, where the soft symbol of the TPC command itself is directed used as a reliability indicator. In addition to the new reliability estimation, the concept of parallel use of TPC algorithms is presented. The results show that the soft symbol reliability estimation decrease the $P_{tx}$ levels with 0.3 dB, thus providing a useful capacity gain. The parallel use of 2 to 4 algorithms is also shown to decrease the sensitivity of the algorithms to the algorithm thresholds used, and thus increase the feasibility of the algorithms in a real world networks.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.67-68
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• 2015

본 논문은 폐루프 고피나스 자속관측기의 P/PI모드를 전환하여 전환점부근 저속에서 모터상수 변동에도 강인한 센서리스 벡터제어가 가능한 전환기법을 제안하였다.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.313-314
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• 2015

본 논문은 3상 4선식 인버터를 이용하여 임의의 전압 파형을 발생하기 위한 우수한 성능의 폐루프 전압 제어기를 제안하고 제어 이득 설정 방법을 제시한다. 먼저, 임의 파형 발생기에 사용된 3상 4선식 인버터 및 LC 필터 회로 구조를 분석하고, 이를 기반으로 한 전압 제어기 구조를 제안한다. 제안된 전압 제어기는 폐루프 형태의 PI 전압 제어기를 사용하고, 과도 특성 개선 및 부하 전류로 인한 전압 왜곡 방지를 위해 인버터 전류 및 부하 전류 정보를 전향 보상에 사용한다. 실험을 통해 전압 지령에 대한 응답 특성이 향상되는 것을 확인할 수 있다.

• The Journal of the Acoustical Society of Korea
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• v.19 no.1
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• pp.16-24
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• 2000

In this paper the performance of a closed-loop power control scheme using variable step size decision method for DS/CDMA based-low earth orbit(LEO) mobile satellite systems in which the long round trip delay is a dominant performance degradation factor is evaluated. Because there are fundamental differences in the characteristics between the LEO mobile satellite channel and terrestrial mobile channel, such as long round trip delay and different elevation angle, these factors are considered in channel modeling based on the European Space Agency(ESA) measurement data. Since the round trip delay (from the mobile terminal to the gateway station via satellite) is typically 10∼20ms in low altitude satellite channels, closed-loop power control is much less effective than it is on a terrestrial channel. Thus, the adaptive power control scheme using a variable step size control is essential for overcoming the long round trip delay and fading due to the elevation angle. It is shown that the standard deviation of signal to interference ratio(SIR) adopting a variable step size closed-loop power control scheme is much less than that of a fixed step size closed-loop power control. Furthermore, we have driven the conclusion that the measurement interval of power control commands is optimal choice when it is twice the round trip delay.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11B
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• pp.1522-1533
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• 2001

In this paper, we handle the estimation method of the received $E_{b}l1_{o}$ for forward closed-loop power control in cdma2000 systems. The estimation of MS-received $E_{b}l1_{o}$ utilizes the symbols related to the forward power control subchannel transmission. The estimation of the received bit energy and noise variance is analyzed for the frequency-selective Rayleigh fading channel. In order to improve SIR (signal-to-interference), the estimation of the received bit energy is made by the coherent combining of the rake-fingers and received I/Q symbols. And, in this paper, we evaluate the performance of forward closed-loop power control according to the mobile speed and the power adjustment step size in terms of the bit error rate (BER) and power control error. Simulation results present the optimal power adjustment step sizes according to the mobile speeds.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.5
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• pp.361-368
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• 2010

This paper presents high speed position controller using stepping motor. The proposed position controller has close loop and open loop mode. In the high speed region, torque angle which is controlled by PI controller and memory based look-up table, is used to keep the reference position. The memory based look-up table produces a torque angle according to motor speed, and the PI controller can compensate the torque angle error. So, the fast dynamic response can be expected in the same position error. The open loop control mode which is divided by 3-modes control the actual position in the low speed and small position error. Each open loop modes are designed to reduce position error and dynamic brake in the stop command. The proposed position control scheme is verified by the practical stepping motor.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.32-40
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• 2015

Code division multiple access (CDMA) is one of the promising medium access control scheme for underwater acoustic sensor networks due to its beneficial features such as robustness against frequency-selective fading and high frequency-reuse efficiency. In this paper, we design a closed-loop power control scheme for the underwater CDMA, to adapt time-varying acoustic channel. In the proposed scheme, sink node sends to sensor nodes the associated path loss which is acquired by uplink-channel analysis based on received packets from the sensor nodes. Then, sensor nodes adjust their transmission power in an adaptive manner to time-varying underwater acoustic channel, according to the informations sent by the sink node.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.222-224
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• 2008

본 논문에서는 3상 VSI의 CVCF 제어를 위해 폐루프 비간섭 DQ 제어기 설계를 제안한다. DQ 제어기를 설계하기위해서 두 개의 간섭항을 폐루프 분리를 통하여 해석적인 PID 제어기를 설계한다. 제안한 PID 제어기는 시간응답을 만족하도록 설계하여 시뮬레이션을 통해 검증한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11A
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• pp.1021-1026
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• 2005

In this paper, we present a novel predictive CDMA closed-loop power control (CLPC) method with a multi-step least squares (LS) linear predictor for time-varying fading channels. The proposed method effectively compensates multiple power control group delays and provides significant performance gains over nonpredictive CLPCs as well as conventional predictive CLPCs with one-step linear predictor.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.152-153
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• 2019

본 논문에서는 캐패시터-분할 타입 능동전력 디커플링 회로를 위한 전압제어 방법을 제안한다. 능동전력 디커플링 회로는 시스템에 필요한 커패시턴스를 낮추어 전해커패시터를 필름 커패시터로 대체하여 시스템 수명과 전력밀도를 높일 수 있는 장점이 있다. 그러나 일반적으로 오픈 루프 제어방식의 전압제어 방식을 사용하여 파라미터 값의 변화에 민감하다는 단점을 가지고 있다. 이에 본 논문에서는 커패시터-분할 타입 능동전력 디커플링 회로를 위한 폐루프 제어 방법을 제안한다.