• Proceedings of the Acoustical Society of Korea Conference
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• 1993.06a
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• pp.80-83
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• 1993

본 논문에서는 양질의 규칙합성을 얻기 위하여, 유성음에 대한 여기신호로 임펄스 스펙트럼과 노이즈 스펙트럼을 다중대역으로 혼합하여 생성한 여기신호를 규칙합성에 적용하는 방법을 제안한다. 이 방법에서는, 분석합성에서 각 프레임별로 요구되었던 혼합여기신호에 대한 정보량 문제를 해결하기 위해 유성음의 정상부분의 한 프레임에 대해 혼합여기신호를 구하여 규칙합성에 적용하였고, 정보량을 더욱 줄이는 방안으로, 켑스트럼 유클리디안 거리를 이용하여 유성음을 분류하여, 각 그룹에 대한 대표 여기신호를 규칙합성의 여기신호로 사용하였다. 제안된 방법으로 음성을 합성한 결과 양질의 합성음을 얻을 수 있음을 확인하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.11a
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• pp.260-261
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• 2010

본 논문에서는 제작된 콘텐츠에 배경음을 간편하고 효과적으로 혼합하기 위해서 녹음된 신호(전경음)를 분석하여 배경음 에너지를 적응적으로 조절하는 배경음혼합 알고리즘을 제안한다. 이를 위해, 제안된 알고리즘은 등청감 곡선 (equal-loudness curve) 및 linear prediction (LP) 분석에 기반하여 전경음신호의 청감 에너지 및 음성신호 존재여부를 결정한다. 이에 따라 전경음에 음성신호가 존재하는 경우에는 음성이 명확하게 들릴 수 있도록 혼합된 배경음의 에너지를 하향 조절하고, 반대로 전경음에 음성신호가 존재하지 않는 경우에는 배경음이 명확하게 들릴 수 있도록 혼합된 배경음의 에너지를 상향 조절한다. 제안된 알고리즘의 효율성을 검증하기 위해, 고정 가중치를 이용하여 배경음을 혼합하는 경우와의 음질 선호도 조사를 실시한 결과, 제안된 알고리즘에 대한 높은 선호도를 보였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.279-286
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• 2015

EMD is a fully data-driven signal processing method without using any predetermined basis function and requiring any user parameters setting. However EMD experiences a problem of mode mixing which interferes with decomposing the signal into similar oscillations within a mode. To overcome the problem, EEMD method was introduced. The algorithm performs the EMD method over an ensemble of the signal added independent identically distributed white noise of the same standard deviation. Even so EEMD created problems when the decomposition is complete. The ensemble of different signal with added noise may produce different number of modes and the reconstructed signal includes residual noise. This paper propose an modified EEMD method to overcome mode mixing of EMD, to provide an exact reconstruction of the original signal, and to separate modes with lower cost than EEMD's. The experimental results show that the proposed method provides a better separation of the modes with less number of sifting iterations, costs 20.87% for a complete decomposition of the signal and demonstrates superior performance in the signal reconstruction, compared with EEMD.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.4B
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• pp.400-405
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• 2001

본 논문에서는 Local Oscillator(LO)의 누설신호 제거를 위해 혼합기의 특성을 이용하여 광대역의 특성을 가지고 RF 채널에 근접한 누설신호를 제거할수 있는 구조를 제안하였다. 제안된 구조는 Half-LO 주파수를 이용하는 방버븡로 LO 누설신호를 일반적인 다른 경우보다 RF 신호대역에서 멀리 떨어진 대역으로 분리시킴으로서 대역 통과여파기로서 쉽게 제거하였다. 상향변환기로서 필요한 저역통과여파기, 대역통과여파기, 그리고 증폭기를 설계하였고 혼합기에 의한 영상성분은 혼합기의 위상을 특성을 이용하여 제거하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.1870-1877
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• 2012

Transient signals generally have short duration and variable length with time-varying and non-stationary characteristics. Thus frame-based pattern matching method is useful for classification of transient signals. In this paper, we propose a new method for classification of underwater transient signals using a Gaussian mixture model(GMM). We carried out classification experiments for various underwater transient signals depending upon the types of noise, signal-to-noise ratio, and number of mixtures in the GMM. Experimental results have verified that the proposed method works quite well for classification of underwater transient signals.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.8
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• pp.1392-1398
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• 2000

In this paper, Sub Harmonic Ring Mixer using Anti-Parallel Diode Pair is studied. Conventional mixers mix LO signal with RF signal and, obtain IF signal from the difference between LO and RF. Sub harmonic ring mixers using APDP mix RF signal with the second harmonic of LO signal, LO frequency needed for conventional receiver is reduced by 1/2.The produced mixer showed 12 dB conversion loss, and 1 dB compression point of IF signal, in respect to RF signal, was found at the 0 dBm RF signal. Isolation LO/IF and LO/RF is 24.6 dB and 22.5 dB respectively. Isolation RF/LO and LO/RF is 32.6 dB and 22.5 dB respectively.

• The Korean Journal of Applied Statistics
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• v.22 no.4
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• pp.759-770
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• 2009

A problem of separating signals from noises is considered, when they are randomly mixed in the observation. It is assumed that the noise follows a Gaussian distribution and the signal follows a Gamma distribution, thus the underlying distribution of an observation will be a mixture of Gaussian and Gamma distributions. The parameters of the mixture model will be estimated from the EM algorithm. Then the signals and noises will be classified by a fixed threshold approach based on multiple testing using positive false discovery rate and Bayes error. The proposed method is applied to a real optical emission spectroscopy data for the quantitative analysis of inclusions. A simulation is carried out to compare the performance with the existing method using 3 sigma rule.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.7A
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• pp.1124-1134
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• 2001

동일 그룹에 속하는 사용자들의 신호 크기가 다른 경우에 대하여 혼합형 다중 사용자 간섭제거 기법에 대한 성능 분석을 하였다. 이를 바탕으로, 기존의 혼합형 간섭제거 기법은 전력 제어를 하지 않거나 전력 제어가 완벽하지 않은 상황에서, 동일 그룹에 속하는 사용자들의 신호 크기 차이가 크게 날 경우, 사용자들의 큰 신호 크기 차이로 인해 전체적인 성능이 떨어지게 됨을 보였다. 이 논문에서 제안한 기법은 신호의 크기를 고려하여 그룹화 알고리즘을 적용하도록 함으로써, 그룹에 속하는 사용자들의 신호 크기 차이가 적도록 그룹을 형성함으로써 혼합형 간섭제거 기법의 성능을 개선하였다. 그룹의 수가 같은 경우 제안된 기법과 기존의 기법의 성능을 비트 오류율을 지표로 하여 성능이 개선됨을 확인하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.239-244
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• 2004

In this paper, we have developed a frequency mixer which can be used as a microwave phase conjugator in the LS band retrodirective antenna system. The mixer as a phase conjugator must have an If signal of which frequency is nearly as high as that of an RF signal, so this fact brings difficulty in the combination of input signals and the design of impedance matching circuit. The circuit configuration is chosen to be of the gate mixer using a pseudomorphic HEMT device. The operating frequencies are 4.00 ㎓, 2.01 ㎓, and 1.99 ㎓ for LO, RF, and IF, respectively. Conversion gain is measured to be 12.5 ㏈ and 1 ㏈ compression point -34 ㏈m at the LO power of -7 ㏈m. The mixer fabricated in this research is the single-ended type, where RF leakage signal appears inevitably at the If port because RF and If frequencies are almost the same. The circuit topology suggested here can be applied directly to the design of balanced-type mixers and phase conjugators.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.3
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• pp.409-416
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• 2022

This paper relates to the blind noise separation method of time-delayed convolutive mixed signals. Since the mixed model of acoustic signals in a closed space is multi-channel, a convolutive blind signal separation method is applied and time-delayed data samples of the two microphone input signals is used. For signal separation, the mixing coefficient is calculated using an inverse model rather than directly calculating the separation coefficient, and the coefficient update is performed by repeated calculations based on secondary statistical properties to estimate the speech signal. Many simulations were performed to verify the performance of the proposed blind signal separation. As a result of the simulation, noise separation using this method operates safely regardless of convolutive mixing, and PESQ is improved by 0.3 points compared to the general adaptive FIR filter structure.