• 대한전기학회논문지
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• 제38권3호
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• pp.237-246
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• 1989

A sliding memory covariance circular lattice (SMC-CL) filter and an efficient ARMA modeling method using the SMC-CL filter are presented. At first, SMC-CL filter is derived based on the geometric approach. Then ARMA process is converted into 2 channel AR process, and SMC-CL filter is applied to it. The structure of SMC-CL filter becomes simpler in case of ARMA modeling due to the whiteness of a driving input process. The parameters of ARMR process can be obtained by the Levinson recursions from the PARCOR coefficients of the second channel of the filter. Computer simulations are performed to show the effctiveness of the proposed algorithm.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.337-340
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• 2002

In data transmission at the digital satellite broadcasting systems, the delay and spread are caused whit receiving original signals from the transmitter in the receiver. So, there are some problems in data fast transmission. Also, transmitted signals ate received in stale of the combination of transmission delay and noise of channel. The affect of channel noise is reduced when increasing transmission power, but as signal interference due to the transmission delay and spread of channel increase in proportion to the transmission power, there is a problem in spite of increasing the transmission power. And there is the problem to add ISI(inter symbol interference) because the property of the channel is limo-varying due to relative moving in the transceiver Therefore, in this paper, a pulse shaping filter for the high-speed service in digital satellite broadcasting systems was designed and reduced the ISI.

• 한국전자통신학회논문지
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• 제8권11호
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• pp.1641-1646
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• 2013

기저대역 채널선택 필터는 외부의 잡음이나 공정상의 변화에 따라 각각의 통신 채널을 선택하기 위해 인가되는 제어 전압이 변동될 수 있다. 본 논문에서는 제어 전압을 일정하게 유지시키기 위해, 전류의 흐름을 감지하여 채널선택 필터의 차단주파수가 자동으로 조정되어 필터 동작이 원활하게 유지되면서 최소 면적을 갖는 전류 비교 방식 전압 안정화 회로를 설계하였다.

• 조명전기설비학회논문지
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• 제28권8호
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• pp.6-13
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• 2014

In this paper, a multiwavelength-switchable first-order fiber flexible filter is newly proposed, which is based on a polarization-diversity loop. The proposed filter consists of a polarization beam splitter, three half-wave plates(HWPs), and two high birefringent fibers(HBFs). The proposed filter has a good flexibility in adjusting relative angular difference between the principal axes of two HBFs by inserting an HWP between two HBFs. The first-order flat-top or narrow band transmission spectra and the zeroth-order transmission spectra, which had a channel spacing of ~0.8nm, could be obtained by controlling the three HWPs, and, in particular, each of them could also be interleaved. In addition, zeroth-order transmission spectra with a channel spacing of ~0.8nm could be flexibly converted into those with a channel spacing of ~0.4nm through the control of three HWPs, and also be interleaved. The transmission characteristics of the proposed filter was theoretically analyzed and experimentally verified.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1911-1913
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• 1997

주파수 특성이 뛰어난 광반사기의 구현을 위한 협대역 반사기에 대한 이론적 해석이 이루어졌으며 grating을 사용하여 광공진을 발생시키며 도파로 결합기를 사용하여 공진 신호를 주도파로에서 다른 도파로로 유도하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권9호
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• pp.4240-4258
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• 2016

A practical iterative channel estimation technique is proposed for the multiple-input-multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system in the high-speed mobile environment, such as high speed railway scenario. In the iterative algorithm, the Kalman filter and data detection are jointed to estimate the time-varying channel, where the detection error is considered as part of the noise in the Kalman recursion in each iteration to reduce the effect of the detection error propagation. Moreover, the employed Kalman filter is from the canonical state space model, which does not include the parameters of the autoregressive (AR) model, so the proposed method does not need to estimate the parameters of AR model, whose accuracy affects the convergence speed. Simulation results show that the proposed method is robust to the fast time-varying channel, and it can obtain more gains compared with the available methods.

• 한국통신학회논문지
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• 제35권7A호
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• pp.623-631
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• 2010

In this paper, various of pilot-assisted channel estimation techniques for 3GPP LTE downlink are tested under multipath Rayleigh fading channel. At first, the conventional channel estimation techniques are applied with linear zero-forcing (ZF) equalizer, such as one dimensional least square (1-D LS) linear interpolation, two dimensional (2-D) wiener filter, the time and frequency dimension separate wiener filter and maximum likelihood estimator (MLE). Considering the practical implementation, we proposed two channel estimation techniques by combining time-dimension wiener filter and MLE in two manners, which showed a good tradeoff between system performance and complexity when comparing with conventional techniques. The nonlinear decision feedback equalizer (DFE) which can show a better performance than linear ZF equalizer is also implemented for mitigating inter-carrier interference (ICI) in our system. The complexity of these algorithms are calculated in terms of the number of complex multiplications (CMs) and the performances are evaluated by showing the bit error rate (BER).

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2000년도 하계종합학술대회논문집
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• pp.17-20
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• 2000

In a digital communication system, the transmission channel may introduce error into the digital signal being transmitted. It would be useful if a process could be devised so that the error could be removed in order to recover the transmitted digital signal. We design a corrective filter that is inverse filter, which will generate an output signal identical to the input signal. in order for two systems connected in cascade to produce an output which is identical to the input signal, the over-all unit sample response of the cascade connection must be a unit sample function.

• 한국광학회지
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• 제19권3호
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• pp.242-245
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• 2008

본 논문에서는 $1{\times}4$ 스위치와 서로 다른 FSR(free spectral ranges)을 갖는 마이크로링 공진기 배열을 결합하여 구현된 광공진기 라우터를 기반으로 하는 집적광학 방식의 4채널 선택 마이크로웨이브(microwave: MW) 필터를 제안하고 구현하였다. 중심 주파수는 링 공진기의 반지름에 따른 FSR에 의해 결정되며, 이를 통해 얻어지는 10 GHz, 16 GHz, 18 GHz, 20 GHz로 구성된 4개의 채널은 광스위치에 제어 전압을 인가하여 개별적으로 선택할 수 있었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 제13회 신호처리 합동 학술대회 논문집
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• pp.193-196
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• 2000

An stereophonic acoustic echo canceller cannot exactly estimate the echo path in the receiving room, because of the cross-correlation between stereo signals. In this paper, the new preprocessing filter is proposed to reduce the cross-correlation between the signals without influence on stereophonic sound. Two channel signals are linearly decorrelated by using orthogonality principles and the attenuated absolute values of the decorrelated signals are added to each channel input signals. Assuming that the power of each channel signal is larger than that of the cross-correlation, computational burden is reduced.