• The Journal of the Acoustical Society of Korea
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• v.42 no.6
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• pp.511-518
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• 2023

Accurate ranging is one of the key factors in the test and evaluation process of underwater vehicles. In particular, when estimating range using Time of Arrival (ToA) values, signals such as Linear Frequency Modulation (LFM), a chirp signal, are highly applicable due to their correlated nature. However, in a Doppler shift environment with mobility, measurement errors may occur due to the range-Doppler coupling effect. In this paper, we propose a signal that compensates for the distance-Doppler coupling effect to reduce the measurement error of the arrival time value. The proposed signal is constructed by superimposing two types of LFM signals, and the range-Doppler coupling effect can be minimized. Through simulations, it is confirmed that the proposed signal is a way to compensate for the distance-Doppler coupling effect in the distance estimation of underwater mobile bodies, reducing the measurement error of the arrival time value.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.168-168
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• 2004

본 논문은 헤테로다인 간섭계를 이용한 레이저 진동 측정기에 대해 기술하고 있다. 상용 레이저 진동 측정기가 대부분 AOM을 이용하여 주파수 천이를 일으키는 반면, 본 연구에서는 Zeeman 안정화 He-Ne 레이저를 사용하므로써, 서로 다른 주파수를 가지는 레이저를 동시에 얻을 수 있었다. 따라서, Zeeman 안정화 He-Ne 레이저를 사용하는 진동측정기의 경우 간섭계 구성을 위해 사용되는 비용을 현저히 줄일 수 있다. 또한, AOM의 고주파 신호를 처리하기 위해서는 RE 대역의 신호처리 회로 설계가 필요하지만, Zeeman 안정화 레이저의 주파수 천이가 낮으므로, 제안된 진동측정기의 신호처리가 용이하다.(중략)

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.12a
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• pp.199-202
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• 2002

신경회로망을 동적 정보처리에 응용하기 위해서는 비대칭 결합 신경회로망에서 생성되는 동적 상태천이에 관한 직관적 이해가 필요하다. 자기결합을 갖고 결합하중치가 비대칭인 순환결합형 신경회로망은 복수 개의 리미트사이클이 기억 가능하다는 것이 알려져 있다. 현재까지 이산시간 모델의 네트워크에 대한 상태천이 해석은 상세하게 이루어져 왔다. 그러나 연속시간 모델에 대한 해석은 네트워크 규모의 증가에 따른 급격한 계산량의 증가 때문에 연구가 그다지 활발하게 이루어지지 않고 있다. 본 논문에서는 각 뉴런이 최근접 뉴런에만 이진화된 결합하중 +1 및 -1로 연결된 연속시간모델 순환결합형 신경회로망의 동적인 상태천이 특성을 해석하여 이산시간 모델에서 기억 가능한 리미트사이클과의 차이점을 분석한다. 또한 연속시간 네트워크 모델에 카오스 신호를 인가하여 리미트사이클간의 천이를 제어할 수 있는 가능성을 분석하여 동적정보처리에 네트워크를 응용할 수 있는 가능성을 검토한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1557-1564
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• 2014

In this paper, we propose a signal detection technique based on the parallel orthogonal matching pursuit (POMP) is proposed for generalized shift space keying (GSSK) systems, which is a modified version of the orthogonal matching pursuit (OMP) that is widely used as a greedy algorithm for sparse signal recovery. The signal recovery problem in the GSSK systems is similar to that in the compressed sensing (CS). In the proposed POMP technique, multiple indexes which have the maximum correlation between the received signal and the channel matrix are selected at the first iteration, while a single index is selected in the OMP algorithm. Finally, the index yielding the minimum residual between the received signal and the M recovered signals is selected as an estimate of the original transmitted signal. POMP with Quantization (POMP-Q) is also proposed, which combines the POMP technique with the signal quantization at each iteration. The proposed POMP technique induces the computational complexity M times, compared with the OMP, but the performance of the signal recovery significantly outperform the conventional OMP algorithm.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.9
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• pp.57-64
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• 2004

In this paper, we propose a RZ/HRZ mixture data transmission method for the asynchronous circuit design to reduce Power consumption. The dual-rail data with Rf decoding scheme is used to design asynchronous circuit, and it is easy to get a completion signal of the data validity from the native data as contrasted with sin91e-rail. However, the dual-rail scheme suffers from large chip area and increasing of Power consumption from all signals by the switching of the return-to-zero. We need to diminish number of circuit switching. The proposed RZ/HRZ data transmission reduces a switching activity to about 50% and it shows 23% lower power consumption than the conventional dual-rail coding with RZ's.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.159-160
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• 2008

차세대 위성항법 시스템은 높은 변조율을 갖는 이진 천이 반송파 변조된 확산신호를 사용한다. 그런데 부호 획득을 위해 기존 선형탐색 기법을 사용할 경우 변조율 증가에 따라 탐색회수가 크게 증가하여 초기고정시간도 증가하는 단점이 나타난다. 이에 본 논문은 차세대 위성항법 시스템이 사용하는 높은 변조율을 갖는 이진천이 반송파 변조된 확산신호를 위한 빠른 부호획득 기법을 제안하고, 복잡도를 분석한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.5
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• pp.1010-1019
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• 2004

In this paper, we represent Nakagami-m fading channel as finite-State Markov Channel (FSMC) and analyze the performance of wireless communication system with varying the fading channel condition. In FSMC model, the received signal's SNR is divided into finite intervals and these intervals are formed into Markov chain states. Each state is modeled by a BSC and the transition probability is dependent upon the physical characterization of the channel. The steady state probability and average symbol error rate of each state and transition probability are derived by numerical analysis and FSMC model is formed with these values. We found that various fading channels can be represented with FSMC by changing state transition index. In fast fading environment in which state transition index is large, the channel can be viewed as i.i.d. channel and on the contrary, in slow fading channel where state transition index is small, the channel can be represented by simple FSMC model in which transitions occur between just adjacent states. And we applied the proposed FSMC model to analyze the coding gain of random error correcting code on various fading channels via computer simulation.

• Journal of Satellite, Information and Communications
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• v.4 no.1
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• pp.21-27
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• 2009

In this paper, we introduce a simulation result of cross ambiguity function (CAF) using time difference of arrival and frequency difference of arrival. This method is generally used to find a geographical location of the unknown radio transmitter. If multiple signals with the same source information are arrived at a receiver via different paths, then they will have different time delays and Doppler shifts. We can estimate the CAF by using these characteristics, and estimate the location of the unknown transmitter. This paper introduces a technique to improve the estimation performance of CAF.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.10
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• pp.1001-1008
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• 1991

.In this paper the efficient clock recovery algorithm is proposed to regenerate the manchester code at the system using the Manchester encoding scheme such as LAN. Mobile communication and digital communication systems. The proposed clock recovery circuit recovers the clock using the two times of the same original transmitted frequency can be completely recovered. The implementation of the proposed clock recovery circuit and the interpretation of test results prove the validity of the proposed algorithm.

• The Journal of the Acoustical Society of Korea
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• v.20 no.2
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• pp.77-85
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• 2001

This paper proposes a method of time-scale modification of polyphonic audio signals based on a sinusoidal model. The signals are modeled with sinusoidal component and noise component. A multiresolution filter bank is designed which splits the input signal into six octave-spaced subbands without aliasing and sinusoidal modeling is applied to each subband signal. To alleviate smearing of transients in time-scale modification a dynamic segmentation method is applied to subbands which determines the analysis-synthesis frame size adaptively to fit time-frequency characteristics of the subband signal. For extracting sinusoidal components and calculating their parameters matching pursuit algorithm is applied to each analysis frame of subband signal. In accordance with spectrum analysis a psychoacoustic model implementing the effect of frequency masking is incorporated with matching pursuit to provide a resonable stop condition of iteration and reduce the number of sinusoids. The noise component obtained by subtracting the synthesized signal with sinusoidal components from the original signal is modeled by line-segment model of short time spectrum envelope. For various polyphonic audio signals the result of simulation shows suggested sinusoidal modeling can synthesize original signal without loss of perceptual quality and do more robust and high quality time-scale modification for large scale factor because of representing transients without any perceptual loss.