• Bulletin of the Korean Mathematical Society
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• v.35 no.1
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• pp.91-97
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• 1998

In this paper we study the Weyl spectrum of weight $\alpha, \omega_\alpha(T)$, of an operator T acting on an infinite dimensional Hilbert space. Main results are as follows. Firstly, we show that the Weyll spectrum of weight $\alpha$ of a polynomially $\alpha$-compact operator is finite, and that similarity preserves polynomial $\alpha$-compactness and the $\alpha$-Weyl's theorem both. Secondly, we give a sufficient condition for an operator to be the sum of an unitary and a $\alpha$-compact operators.

• Bulletin of the Korean Mathematical Society
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• v.43 no.4
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• pp.715-722
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• 2006

In this paper, we show that if T is a hyponormal operator on a non-separable Hilbert space H, then $Re\;{\omega}^0_{\alpha}(T)\;{\subset}\;{\omega}^0_{\alpha}(Re\;T)$, where ${\omega}^0_{\alpha}(T)$ is the weighted Weyl spectrum of weight a with ${\alpha}\;with\;{\aleph}_0{\leq}{\alpha}{\leq}h:=dim\;H$. We also give some conditions under which the product of two ${\alpha}-Weyl$ operators is ${\alpha}-Weyl$ and its converse implication holds, too. Finally, we show that the weighted Weyl spectrum of a hyponormal operator satisfies the spectral mapping theorem for analytic functions under certain conditions.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.3
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• pp.178-184
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• 2007

The EEG signal in general can be categorized as the Alpha wave, the Beta wave, the Theta wave, and the Delta wave. The alpha wave, showed in stable state, is the dominant wave for a human EEG and the beta wave displays the excited state. The subject of this paper was to recognize the stable state of EEG quantitatively using wavelet transform and power spectrum analysis. We decomposed EEG signal into the alpha wave and the beta wave in the process of wavelet transform, and calculated each power spectrum of EEG signal, using Fast Fourier Transform. And then we calculated the stable state quantitatively by stable state ratio, defined as the power spectrum of the alpha wave over that of the beta wave. The study showed that it took more than 10 minutes to reach the stable state from the normal activity in 69 % of the subjects, 5 -10 minutes in 9%, and less than 5 minutes in 16 %.

• Journal of Communications and Networks
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• v.16 no.2
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• pp.193-201
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• 2014

In cognitive radio networks, the packet transmissions of the secondary users (SUs) can be interrupted randomly by the primary users (PUs). That is to say, the PU packets have preemptive priority over the SU packets. In order to enhance the quality of service (QoS) for the SUs, we propose a spectrum access strategy with an ${\alpha}$-Retry policy. A buffer is deployed for the SU packets. An interrupted SU packet will return to the buffer with probability ${\alpha}$ for later retrial, or leave the system with probability (1-${\alpha}$). For mathematical analysis, we build a preemptive priority queue and model the spectrum access strategy with an ${\alpha}$-Retry policy as a two-dimensional discrete-time Markov chain (DTMC).We give the transition probability matrix of the Markov chain and obtain the steady-state distribution. Accordingly, we derive the formulas for the blocked rate, the forced dropping rate, the throughput and the average delay of the SU packets. With numerical results, we show the influence of the retrial probability for the strategy proposed in this paper on different performance measures. Finally, based on the trade-off between different performance measures, we construct a cost function and optimize the retrial probabilities with respect to different system parameters by employing an iterative algorithm.

• Journal of the Ergonomics Society of Korea
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• v.20 no.3
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• pp.1-9
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• 2001

In the present study, the correlation between subjective assessment and EEG for essential odors were investigated quantitatively. EEG signals were measured from 19 electrodes according to the International 10-20 system (Fp1, Fp2, F3/4, F7/8, Fz, C3/4, Cz, P3/4, Pz, T3/4, T5/6, O1/2) from 8 healthy males subjects for four odor(Rose oil bulgarian, Lemon oil misitano, jasmin abs, Laverder oil france (KIMEX co. Ltd) conditions. The result of the subjective assessment shows the most pleasant odor for each subject. and the power spectrum of ${\alpha}/({\alpha}+{\beta})$ of EEG signals from the most pleasant odor was compared with those from the control condition, which has no odor at all. Power spectrum of ${\alpha}/({\alpha}+{\beta})$ of EEG from the most pleasant odor was increased significantly at T4, T6 compared to the control condition. This result implies that the parameter, power spectrum of ${\alpha}/({\alpha}+{\beta})$, could be an important index for signifying the levels of pleasantness for odors.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.879-880
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• 2006

The subject of this paper is to recognize the stable state of EEG using wavelet transform and power spectrum analysis. An alpha wave, showed in stable state, is dominant wave for a human EEG and a beta wave displayed excited state. We decomposed EEG signal into an alpha wave and a beta wave in the process of wavelet transform. And we calculated each power spectrum of EEG signal, an alpha wave and a beta wave using Fast Fourier Transform. We recognized the stable state by making a comparison between power spectrum ratios respectively.

• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.4067-4071
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• 2021

The ¹³C (α,n)¹⁶O reaction cross-section is important data for nuclear physics, astrophysical, and neutrino physics experiments, however, they exhibit uncertainties due to the discrepancies in the experimental data. In this study, using the Nedis-2m program code, the energy spectrum of α-induced neutrons in a thin carbon target was calculated and the corresponding reaction cross-section was refined in the alpha particle energy range of 5-8 MeV. The results were used to calculate the intensity and energy spectrum of background neutrons produced in the liquid scintillator of KamLAND. The results will be useful in a variety of astrophysical and neutrino experiments especially those based on LS or Gd-LS detectors.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.101-108
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• 2013

In this paper, we propose a method in which the negative acknowledge (NACK) message is used as command for cooperation and spectrum sharing. This allows for an automatic request for cooperation and sharing when the direct link of the primary user is in outage, and also allows for saving the number of control messages in cooperation-spectrum sharing based paradigm. In the sharing phase, the selected relay shares a power fraction of $1-{\alpha}$ for secondary transmitted signal while the remaining of ${\alpha}$ is for primary retransmitted signal. In the case of no relay collected, primary transmitter uses NACK as a command to retransmit the signal with fully power fraction (${\alpha}=1$). Both systems are assumed to employ BPSK signals. In this scheme, we propose the joint optimal decoding in the secondary user. The frame error rate (FER) performance at both systems is then analyzed. The theoretical and simulation results validate the analysis and confirm the efficiency of the protocol.

• YAKHAK HOEJI
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• v.13 no.4
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• pp.121-124
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• 1969

인삼의 "methanolic extract"을 분획하여 염기성 성분을 모으고 GLC-Mass on line, NMR spectrum에 의하여 $\alpha$-pyrrolidone과 수종의 염기성성질이 공존함을 증명하였다.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.04a
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• pp.265-270
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• 2000

본 연구에서는 EEG 반응을 통하여 향이 인간에 미치는 영향을 평가하였다. 24-26세의 8명의 남성 피험자를 대상으로 국제 기준 전극법에 따라 19 부위에서 EEG를 기록하여 분석하였다. 실험에 사용한 향은 Rose oil bulgarian, Lemon oil misitano, Jasmin abs, Laverder iol france (KIMEX co. Ltd) 등 4가지의 천연오일을 사용하였다. 향에 대한 선입견을 배제하고 각 피실험자별로 주관적 평가를 통하여 가장 쾌하게 느낀 향이 제시되었을 때의 뇌파와 무향 상태 뇌파에서 $\alpha$/$\beta$ 대역의 power spectrum 비를 구하여 비교하였다. 무향 상태에 비해 각 피실험자별로 가장 쾌하게 느낀 향을 제시했을 때 F3, Fz, F4, T4 부분에서 $\alpha$/$\beta$ 대역의 power spectrum 비의 통계적으로 유의한 증가를 관찰할 수 있었으며 이는 $\alpha$/$\beta$ 대역의 power spectrum 비가 향의 쾌도를 측정하는 하나의 새로운 척도가 될 수 있음을 시사한다.