• 제어로봇시스템학회논문지
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• 제8권4호
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• pp.308-312
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• 2002

To determine the natural frequencies and damping ratios of composite laminated plates, we present an officient modal parameter estimation technique by developing residual spectrum based structural system reconstruction. The modal parameters can be estimated from poles and residues of the system transfer functions, derived from the state space system matrices. From vibration tests on cross-ply and angle-ply composite laminates, the natural frequencies and damping ratios can be estimated using the modal coordinates of the structural dynamic system reconstructed from the experimental frequency response functions. These results are compared with those of finite element analysis and single-degree-of-freedom curve fitting.

• 전자공학회논문지A
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• 제33A권6호
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• pp.178-188
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• 1996

In this paper, we propose a new opto-digital object recognition system which has rotation, scale, and shift invariant characteristics. The fourier power spectrum of the object image is modified to get shift invariance. The log-polar transform is used for rotation and scale invariance. And the decision of similarities is performed by nonlinear joint transform correlator (NJTC) that can control the ratio of phase and amplitude signals. Experimental verification of th eproposed optical object recognition system is presented.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권3호
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• pp.1333-1343
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• 2016

Spectrum sharing in centrally controlled cognitive radio (CR) networks has been widely studied, however, research on channel access for distributively controlled individual cognitive users has not been fully characterized. This paper conducts an analysis of random channel access of cognitive users controlled in a distributed manner in a CR network. Based on the proposed estimation method, each cognitive user can estimate the current channel condition by using its own Markov-chain model and can compute its own blocking probability, collision probability, and forced termination probability. Using the proposed scheme, CR with distributed control (CR-DC), CR devices can make self-controlled decisions based on the status estimations to adaptively control its system parameters to communicate better.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.257-260
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• 1993

A new method of spindle waveform detection is presented for the automated analysis of sleep EEG. The method is based on the combined application of signal conditioning in the time-domain and local spectrum analyzing in the frequency-domain. The overall detection system is implemented and, tested in real-time with a total of 24 hour data obtained from four subjects. The result shows an average agreement of 86.7% with the visually inspected result.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1995년도 추계학술대회 학술발표 논문집
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• pp.98-103
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• 1995

In this paper, a method is presented for finding an optimal temperature control pattern in microwaveoven using genetic algorithm. Power spectrum of temperature variance of charcoal is obtained and oven system modeling with fuzzy-neural-network is explained. Fan on/off timing is converted to strings in gene pool and then genetic iterations make the power spectrum of simmulated temperature variance of microwave oven closer to that o charcoal.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1749-1753
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• 2003

We proposed several systems for 1Giga bit Modem. The first, Binary ASK(Amplitude Shift Keying) system has a high speed shutter transmitter and no IF(Intermediate Frequency) receiver only by symbol synchronization. The advantage of proposed system is that circuitry is very simple without IF process. The disadvantage of proposed system are that line spectrum occurs interference to other channels, and enhancement to 4-level system is impossible due to its large SNR degradation. The second, Binary phase modulation system has a high speed shutter transmitter and IF-VCO(IF-Voltage Controlled Oscillator) control by base-band phase rotation. Polarity of shutter window is changed by the binary data. The window should be narrow same as above ASK. The advantage of proposed system is which error rate performance is superior. The disadvantage of proposed system are that Circuitry is more complex, narrow pull-in range of receiver caused by VCO and spectrum divergence by the non-linear amplifier. The third, 4-QAM(Quadrature Amplitude Modulation)system has a nyquist pulse transmitter and IF-VCO control by symbol clock. The advantage of proposed system are that signal frequency band is a half of 1GHz, reliable pull-in of VCO and possibility of double speed transmission(2Gbps) by keeping 1GHz frequency-band. The disadvantage of proposed system are that circuit complexity of pulse shaping and spectrum divergence by the non-linear amplifier.

• 한국지능시스템학회논문지
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• 제23권2호
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• pp.172-177
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• 2013

BCI (Brain Computer Interface)는 인간의 뇌에서 측정된 EEG (Electroencephalogram)를 활용하여 의수와 같은 기기를 조종할 수 있는 좋은 방법 중 하나이다. 본 논문에서는 EEG와 힘과의 관계를 알아보고자 최대수축악력 (MVC)의 25%, 50%, 75%로 3개의 등급으로 나누어 EEG 변화를 측정하였다. 얻어진 EEG data를 FFT와 power spectrum analysis로 ${\alpha}$, ${\beta}$, ${\gamma}$파로 나누어 각 파형의 파워 값을 구한 뒤, 구해진 EEG 파워 값을 PCA와 LDA를 사용하여 특징 추출 및 분류를 하였다. 실험 결과 25%의 악력을 가할 때 보다 75%의 악력 때 더 높은 EEG 파워의 증가를 확인하였고, 왼손과 오른손은 각각 52.03%와 77.7%의 분류율을 나타내었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권8호
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• pp.1894-1912
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• 2012

This paper proposes a system called Wireless Link based on Global Communication Channel (WLGCC) to enhance the spectrum sharing between digital broadcasting (DB) services and the cognitive radio (CR) system in the licensed band of 470-790 MHz. The WLGCC aims to enhance the spectrum sensing and geolocation database (GLD) spectrum sharing methods in the CR system. Spectrum sensing can be enhanced by receiving the status of the used frequencies from the WLGCC, thereby eliminating the need for a low detection threshold (i.e., avoiding the hidden node problem). In addition, the GLD can be enhanced by providing a reliable communication link between the database and the CR device in the form of an unused TV white space that is reserved as the proposed Global Communication Channel (GCC). This paper analyzes the coexistence of the new WLGCC system and the DB service in terms of avoiding additional interference. Specifically, we mathematically determine the WLGCC parameters, such as the in-band and out-of-band power levels, and operation coverage, and verify them using Monte Carlo simulation. The results show that WLGCC does not degrade the existing DB service and reliably transmits information of the vacant (or used) frequency bands to the CR.

• Journal of electromagnetic engineering and science
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• 제11권1호
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• pp.34-41
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• 2011

This paper proposes a systematic design for a precoding codebook for a transmit-ing space-division multiple access (TN-SDMA) sharing spectrum with existing fixed wireless service (FWS). Based on an estimated direction angle of a victim FWS system, an interfering transmitter adaptively constructs a codebook, forming a transmit in the direction angle, while satisfying orthogonal beamforming constraints. Sum throughput results indicate that the throughput loss of TN-SDMA relative to a practical SDMA, called per user unitary and rate control ($PU^2RC$), is lower at larger number of transmission antennas, lower signal-to-noise ratio, or a smaller number of users. In particular, a small loss (12% throughput loss) is provided for practical system parameters. Spectrum sharing results confirm that TNSDMA efficiently shares spectrum with FWS systems by reducing protection distance to more than 66 %. Although a TN-SDMA system always has lower throughput compared to $PU^2RC$ in non-coexistence scenarios; it offers an intriguing opportunity to re-use a spectrum already allocated to an FWS.

• International Journal of Internet, Broadcasting and Communication
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• 제8권3호
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• pp.69-77
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• 2016

Maximum utilization of unused license spectrum is one of key factor in cognitive radio network which can handle the large number of systems and devices connected on smart grid AMI network. The central intelligence control system has responsibility to accept new technologies and users for automation. To ensure a reliable communication in smart grid system through cognitive network, a minimum mean square error (MSE) signal using unused licensed spectrum (or frequency) is necessary to be detected with small decision error. In this paper, we introduce a user control wireless smart grid system with minimum MSE using LMS algorithm.