• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.1
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• pp.8-11
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• 2012

Automated Vision Inspection (AVI) systems automatically detect any defect feature in a surface image. The performance of the system can be measured under a special circumstances such as ultimate defect detection. In this situation, the defect signal level is similar to noise level and it becomes hard to make a solid decision with AVI systems. In this paper, we propose an effective preprocessing technique to enhance SNR (Signal to Noise Ratio). The method is motivated by some principles of HVS (Human Visual System) and RLC (Run Length Coding) techniques is used for this purpose. The proposed preprocessing technique enhances SNR under ultimate defect conditions and improves overall performance of AVI system.

• ETRI Journal
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• v.35 no.3
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• pp.371-377
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• 2013

An effective signal detection algorithm with low complexity is presented for multiple-input multiple-output orthogonal frequency division multiplexing systems. The proposed technique, QR-MLD, combines the conventional maximum likelihood detection (MLD) algorithm and the QR algorithm, resulting in much lower complexity compared to MLD. The proposed technique is compared with a similar algorithm, showing that the complexity of the proposed technique with T=1 is a 95% improvement over that of MLD, at the expense of about a 2-dB signal-to-noise-ratio (SNR) degradation for a bit error rate (BER) of $10^{-3}$. Additionally, with T=2, the proposed technique reduces the complexity by 73% for multiplications and 80% for additions and enhances the SNR performance about 1 dB for a BER of $10^{-3}$.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.2
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• pp.1-8
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• 2010

In order to determine the possibility of using NDGPS signals for flight operations, in-flight measurements of signals transmitted from various ground reference stations(RS) were conducted along the air routes of South Korea. Signal strength and signal to noise ratio(SNR) data were collected along domestic flight routes and recorded with time. By using three-dimensional geographical position data of the aircraft, signal strength data of en-route position were calculated and used to obtain scatter-plot of signal strength. These results were used to outline the effective coverage and field strength hemispheres of the selected DGPS signals.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.77-79
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• 2013

본 논문에서는 광원 정보를 사용하여 다양한 재생환경에서 효과적인 홀로그래픽 비디오 서비스를 제공하기 위한 방법을 제안한다. 제안하는 기법에서 부호화 과정에서는 가우시안 블러를 적용한 영상의 개수를 조절, 분리 하고 다운 샘플링 한 하나의 영상 압축을 한 뒤 전송한다. 이 영상을 다운 샘플링, 업 샘플링, 보간법, 양방향 필터 (Bi-lateral filter) 등의 기법을 이용하여 획득한 영상과 나머지 영상을 다운 샘플링과 업 샘플링 하여 더한 영상의 차를 압축하여 수신측으로 전송한다. 복호화 과정에서는 압축된 광원 정보를 복원한 후 기본계층 정보를 가진 영상을 업 샘플링과 보간법, 양방향 필터 (Bi-lateral filter) 등의 기법을 적용하고 수신자의 환경과 고려에 따라 차영상을 더 한 후 CGH를 통해 홀로그램을 획득하였다. 실험을 통해 제안하는 기법이 기존의 방법들 보다 우수한 홀로그램을 복원 할 수 있다는 것을 확인하였다.

• The Journal of the Acoustical Society of Korea
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• v.18 no.2
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• pp.25-31
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• 1999

An array aperture synthesis technique is proposed. The proposed method does not require the condition that the overlapped hydrophones have the identical position in space to estimate the phase correction factors. while the existing ETAM algorithm does. Therefore the proposed method increases the available data applied to extend the effective aperture length of the towed array. From the numerical experiments, the proposed method can reduce the mean square error in estimating the direction of a target signal.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.880-883
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• 2002

We propose an effective wavelength converter method using frequency shifter for photonic node, and examine the scalability of Generalized Multiprotocol Label Switching (GMPLS) networks. The ana1ysis is examined based on signal to noise ratio (SNR) for present 2.4 and 10 Gbit/s Synchronous Digital Hierarchy (SDH) networks, and next generation 2.7 and 10.8 Gbit/s Optical Transport Networks (OTN) format The proposed 100 channels GMPLS networks using optical frequency shifters are shown to be applicable to transmission network spanning over 1206 km(24 nodes) in 2.7 Gbit/s trunk networks. Transmission over more than 310 km (6 nodes) is also possible in 2.7 Gbit/s Metroporitan Area Networks(MAN).

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1098-1102
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• 1990

We consider a method for enhancement of speech signal degraded by additive random noise with time-variant and/or colored natures. For enhancement of speech signal with such noise, it is effective to utilize the natures of speech and noise. The objective of enhancement of speech is to improve the overall quality and the articulation of speech degraded by the time-variant and/or colored random noise. In the proposed method the distribution model of speech spectrum is given as information to noise reduction system. The proposed system can improve about lOdB in SNR when the input SNR is 0 dB.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.982-985
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• 1999

An efficient technique to trade off speed for resolution is the sigma-delta modulation (SDM). This paper proposes a new SDM architecture to improve conversion rates and SNR(Signal-to Noise Ratio) by using master clock and four divided clock. The charateristics of the proposed SDM are simulated in MATLAB environment. and optimizing the capacitor sizes is done by iterative processing. other analog characteristics are simulated using 0.65${\mu}{\textrm}{m}$ n-well CMOS process, double poly and single metal. The result of simulation shows that more increasing the effective bits of internal ADC/DAC, bigger the improvement of SNR.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.1
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• pp.19-27
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• 1988

In the user-network interface for the parcticing ISDN, an effective phase aligned time compression multiplexing transmission system is designed and analyzed in the 2 wire passive BUS. In TCM, tha average SNR due to crosstalk from adjacent channelis 9.72(dB), and in regarding the phase aligned process, frames are designed to have maximum propagation time of 6(us) so that the connection distance is extended by 0.8(Km). Therefore, the proposed transmission system is suitable for the connection between end-subscriber and network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.12
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• pp.3237-3256
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• 2012

In the context of effective usage of a scarce spectrum resource, emerging wireless communication standards will demand spectrum sharing with existing systems as well as multiple access with higher spectral efficiency. We mathematically analyze the sum throughput of a spectrum sharing space-division multiple access (SDMA) system, which forms a transmit null in the direction of other coexisting systems while satisfying orthogonal beamforming constraints. For a large number of users N, the SDMA throughput scales as log N at high signal-to-noise ratio (SNR) ((J-1) loglog N at normal SNR), where J is the number of transmit antennas. This indicates that multiplexing gain of the spectrum sharing SDMA is $\frac{J-1}{J}$ times less than that of the non-spectrum sharing SDMA only using orthogonal beamforming, whereas no loss in multiuser diversity gain. Although the spectrum sharing SDMA always has lower throughput compared to the non-spectrum sharing SDMA in the non-coexistence scenario, it offers an intriguing opportunity to reuse spectrum already allocated to other coexisting systems.