• 호남수학학술지
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• 제45권4호
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• pp.598-609
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• 2023

The purpose of this article is to obtain the spectrum, fine spectrum, approximate point spectrum, defect spectrum and compression spectrum of the double band matrix U (a₀, a₁, a₂; b₀, b₁, b₂), b₀, b₁, b₂≠0 on the sequence space ℓ_p (1 < p < ∞).

• East Asian mathematical journal
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• 제23권2호
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• pp.135-149
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• 2007

In 1975, Wenger [4] determined the fine spectra of $Ces{\grave{a}}ro$ operator $C_1$ on c, the space of convergent sequences. In [7], the spectrum of the Rhaly operators on $c_0$ and c, under the assumption that ${lim}\limits_{n{\rightarrow}{\infty}}(n+1)a_n\;=\;L\;{\neq}\;0$, has been determined. In this paper the author determine the fine spectra of the Rhaly matrix $R_a$ as an operator on the space c, with the same assumption.

• Kyungpook Mathematical Journal
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• 제57권3호
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• pp.441-455
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• 2017

In this article we have determined the spectrum and fine spectrum of the lower triangular matrix B(r, s) on the Hahn sequence space h. We have also determined the approximate point spectrum, the defect spectrum and the compression spectrum of the operator B(r, s) on the sequence space h.

• 방송과미디어
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• 제11권1호
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• pp.68-77
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• 2006

The Cognitive Radio (CR) technology is a promising solution for exploiting the limited spectrum resources and providing flexibility of spectrum usage. Future interactive broadcasting service can be realized by utilizing CR concept, since the up-link return channel can be found by the spectrum sensing method, which is core functional block of the CR system. In this paper, the spectrum sensing technologies of CR system is presented. First the system architecture of the CR with spectrum sensing block is presented. The suggested spectrum sensing technique consists of the coarse and the fine spectrum sensing. The coarse spectrum sensing technique adopted the wavelet transform to provide the multi-resolution sensing feature - Multi-Resolution Spectrum Sensing (MRSS). The fine spectrum sensing technique uses the beneficial properties of the autocorrelation function Analog Auto-Correlation (AAC). The simulation results for the proposed sensing technologies are presented for various incumbent signals.

• ETRI Journal
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• 제26권6호
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• pp.657-660
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• 2004

We propose a fine phase tuner and a rounding processor for a numerically controlled oscillator (NCO), yielding a reduced phase error in generating a digital sine waveform. By using the fine phase tuner presented in this paper, when the ratio of the desired sine wave frequency to the clock frequency is expressed as a fraction, an accurate adjustment in representing the fractional value can be achieved with simple hardware. In addition, the proposed rounding processor reduces the effects of phase truncation on the output spectrum. Logic simulation results of the NCO using these techniques show that the noise spectrum and mean square error (MSE) for eight output bits of a 3.125 MHz sine waveform are reduced by 8.68 dB and 5.5 dB, respectively, compared to those of the truncation method, and 2.38 dB and 0.83 dB, respectively, compared to those of Paul's scheme.

• Nuclear Engineering and Technology
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• 제17권2호
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• pp.129-135
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• 1985

중성자 차폐계산에 미치는 칠의 공명에너지 영역에서의 미세군 및 소수군 구조에 의한 효과와 축약과정에서 사용되는 가중스펙트럼에 의한 효과를 ANISN 코드와 ENDF/B-IV자료로써 평가하였다. 다루어진 문제는 소수군효과, 철의 두께 증가에 의한 영향 및 고려된 계를 대상으로한 미상군계산에서 얻은 스펙트럼을 사용한 군축약효과이다. 이용된 군정수와 코드의 정확성을 검토하기 위해, 매우 정확한 계산정도를 갖고 있는 연속에너지 Monte Carlo코드 VIM에 의한 벤치마크계산을 수행하고 결과를 비교-검토하였다.

• Nuclear Engineering and Technology
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• 제44권2호
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• pp.207-224
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• 2012

This article discusses selects of some outstanding problems in nuclear reactor analysis, with proposed approaches thereto and numerical test results, as follows: i) multi-group approximation in the transport equation, ii) homogenization based on isolated single-assembly calculation, and iii) critical spectrum in Monte Carlo depletion.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1999년도 추계학술대회논문집
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• pp.235-242
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• 1999

Wave which propagate from the offshore cause transformation of diffraction, refraction, and reflection etc. in coming in the coastal by depth change. Especially, Wave strongly show the charcateristics of rancom wave in the coastal zone. Developed wave model until a recent date analysed regular waves with height and period equal to those of the significant wave, In case of Monochromatic wave, it can be analysed fine in the offshore, but differ from in coastal zone. In this study, form of governing equation is parabolic mild slope equation. This model calculated random wave for using frequency spectrum and directional spectrum from input data condition of wave. This model is applied to Vincent shoal and compared with laboratory experimental data. The results agreed well with laboratory data.

• Journal of Astronomy and Space Sciences
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• 제33권2호
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• pp.75-92
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• 2016

It is generally believed that the high energy emissions from isolated pulsars are emitted from relativistic electrons/positrons accelerated in outer magnetospheric accelerators (outergaps) via a curvature radiation mechanism, which has a simple exponential cut-off spectrum. However, many gamma-ray pulsars detected by the Fermi LAT (Large Area Telescope) cannot be fitted by simple exponential cut-off spectrum, and instead a sub-exponential is more appropriate. It is proposed that the realistic outergaps are non-stationary, and that the observed spectrum is a superposition of different stationary states that are controlled by the currents injected from the inner and outer boundaries. The Vela and Geminga pulsars have the largest fluxes among all targets observed, which allows us to carry out very detailed phase-resolved spectral analysis. We have divided the Vela and Geminga pulsars into 19 (the off pulse of Vela was not included) and 33 phase bins, respectively. We find that most phase resolved spectra still cannot be fitted by a simple exponential spectrum: in fact, a sub-exponential spectrum is necessary. We conclude that non-stationary states exist even down to the very fine phase bins.

• ETRI Journal
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• 제45권5호
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• pp.874-886
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• 2023

A joint resource-optimization scheme is investigated for nonorthogonal multiple access (NOMA)-enhanced scalable video coding (SVC) multicast in unmanned aerial vehicle (UAV)-assisted radio-access networks (RANs). This scheme allows a ground base station and UAVs to simultaneously multicast successive video layers in SVC with successive interference cancellation in NOMA. A video quality-maximization problem is formulated as a mixed-integer nonlinear programming problem to determine the UAV deployment and association, RAN spectrum allocation for multicast groups, and UAV transmit power. The optimization problem is decoupled into the UAV deployment-association, spectrum-partition, and UAV transmit-power-control subproblems. A heuristic strategy is designed to determine the UAV deployment and association patterns. An upgraded knapsack algorithm is developed to solve spectrum partition, followed by fast UAV power fine-tuning to further boost the performance. The simulation results confirm that the proposed scheme improves the average peak signal-to-noise ratio, aggregate videoreception rate, and spectrum utilization over various baselines.