• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2002.11a
• /
• pp.9-14
• /
• 2002

Direct-conversion receiver(DCR) architecture has superior advantages in size, cost, and power over superheterodyne receiver architectures. However, the use of direct-conversion receiver architecture has been limited due to the direct-current offset noise. The ac coupling, which is used to overcome the direct-current offset noise, causes an inter-symbol interference(ISI), whose effects can be effectively mitigated using an equalizer. In this paper, the performance of a direct-conversion receiver with ac coupling in the presence of direct-current offset is analyzed via computer simulation. The simulation result shows that by using decision feedback equalizer with LMS(Least Mean Square) algorithm, signal-to-noise ratio loss of the direct-conversion receiver compared to the idea receiver can be reduced to less than 1㏈ for corner frequencies as large as 10% of the symbol rate.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.6C
• /
• pp.516-522
• /
• 2010

In this paper, the carrier frequency offset estimator is proposed for the China multimedia mobile broadcasting (CMMB). The fractional carrier frequency offset is estimated by utilizing the cyclic prefix in each CMMB symbol. In addition, the integer carrier frequency offset can be estimated with the synchronization signal in every CMMB frame. The proposed estimator is the most suitable for the frame structure of CMMB. It shows a prominent performance even in timing offset and multipath conditions.

• Journal of Electrical Engineering and information Science
• /
• v.2 no.3
• /
• pp.132-138
• /
• 1997

Electrical characteristics of split-gate flash EEPROM with triple polysilicon is investigated in terms of effects of floating gate and offset gate. In order to search for t the effects of offset gate on programming characteristics, threshold voltage and drain current are studied with variation of control gate voltage. The programming process is believed to depend on vertical and horizontal electric field as well as offset gate length. The erase and program threshold voltage are found to be almost constant with variation of control gate voltage above 12V, while endurance test indicates degradation of program threshold voltage. With increase of offset gate length, program threshold voltage becomes smaller and the drain source voltage just after program under constant control gate voltage becomes higher.

• Proceedings of the KIEE Conference
• /
• 2001.11b
• /
• pp.118-120
• /
• 2001

This paper presents a distance relaying algorithm based on the Discrete Fourier Transform(DFT) for elimination of DC-Offset. When the DFT is applied to current signal. the real and imaginary parts of fundamental component consist of fundamental component itself and DC-Offset. The DC-Offset is calculated by four consecutive values of the imaginary components, so that the fundamental component can be accurately estimated. Performance evaluation is presented for A-phase ground faults on 154kV 80km overhead transmission line. The proposed algorithm is inspected by software simulation and hardware simulation.

• ETRI Journal
• /
• v.34 no.2
• /
• pp.147-158
• /
• 2012

In this paper, we present a demodulation structure suitable for a reader baseband receiver in a passive radio frequency identification (RFID) environment. In a passive RFID configuration, an undesirable DC-offset phenomenon may appear in the baseband of the reader receiver, which can severely degrade the performance of the extraction of valid information from the received tag signal. To eliminate this DC-offset phenomenon, the primary feature of the proposed demodulation structures for the received FM0 and Miller subcarrier signals is to reconstruct the signal corrupted by the DC-offset phenomenon by creating peak signals from the corrupted signal. It is shown that the proposed method can successfully detect valid data, even when the received baseband signal is distorted by the DC-offset phenomenon.

• Proceedings of the KIPE Conference
• /
• 2018.07a
• /
• pp.422-423
• /
• 2018

쇄교자속 기반 센서리스 제어는 저속에서 위치 추정 특성이 우수해 낮은 속도의 운전 영역을 가지는 애플리케이션에 많이 쓰인다. 그러나 계측 정보 오차와 모터 파라미터 변동으로 DC-offset이 발생하는 문제가 있다. 이러한 현상을 방지하기 위해 운전 주파수를 고려한 낮은 차단주파수를 갖는 HPF를 사용했으나, 낮은 DC 저감률로 인해 추정 자속에 DC 성분이 남는 문제점이 있다. 따라서 본 논문에서는 HPF의 차단주파수를 모터 운전주파수에 동기화하여 DC-offset 저감률을 높이고 DC-offset이 시스템에 미치는 정도에 따라 선택적으로 차단주파수를 가변함으로써 위상 앞섬도 감소시키는 방법을 제안한다. 제안된 방법은 Matlab/Simulink에 의해 검증된다.

• Journal of Institute of Control, Robotics and Systems
• /
• v.12 no.12
• /
• pp.1235-1240
• /
• 2006

Previous isotropy analysis of a caster wheeled omnidirectional mobile robot(COMR) has been made under the assumption that the steering link offset is equal to the caster wheel radius. Nevertheless, many practical COMR's in use take advantage of the steering link offset different from the wheel radius, mainly because of improved stability. This paper presents the isotropy analysis of a fully actuated COMR with variable steering link offset, which can be considered as the generalization of the previous analysis. First, the kinematic model of a COMR under full actuation is obtained based on the orthogonal decomposition of the wheel velocities. Second, the necessary and sufficient conditions for the isotropy of a COMR are derived and examined to categorize three different groups, each of which can be dealt with in a similar way. Third, for each group, the isotropy conditions are further explored so as to identify all possible isotropic configurations completely.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.30 no.2
• /
• pp.23-33
• /
• 2012

With the development of many display technologies currently applied to them in the field of printed electronics, there have been many researches that high resolution printing for thin and uniform pattern. In this paper, printing ink flow properties in the reverse offset mechanism were simulated. The aim of this research is to expect the ink flow behavior between cliches to make fine pattern by a printing technique which is a reverse offset. The simulation results show that almost the same as the experiments and the flow behavior according to the ink film thickness and printing pressure changes could be expected.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.8
• /
• pp.23-31
• /
• 2015

This paper proposes an advanced distance relaying based on the DC offset removal filter to minimize the effects of DC offset on a double circuit transmission line. The proposed DC offset removal filter uses only one cycle of data for phasor extraction computation, which does not need to preset the time constant of the DC offset component. This proposed distance relaying uses not only the residual current of the faulted circuit but also mutual current of the healthy adjacent circuit. A series of off-line test results using ATP simulation data show the effectiveness of the an advanced distance relaying.

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.289-291
• /
• 2004

ln this paper, A dc-offset elimination novel algorithm based on an An model is proposed. The algorithm can eliminate dc-offset rapidly than other algorithms. The signal of fault current can be presented as a linear equation combined sinusoidal with exponential signals. Then, the linear equation can be presented an auto-regressive(AR) model and do-offset can be calculated by the equation of AR model. So it is possible to be removed the dc-offset from the original current signal. Performance evaluation of the algorithm was tested on condition that A-phase ground fault on 154kV 25km overhead transmission line.