• 한국분말재료학회지
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• 제9권5호
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• pp.341-345
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• 2002

Nanoparticles of $Fe_2O_3$ with a mean particle size of 4-30 nm have been prepared by a pulsed wire evaporation method, and its structural and magnetic properties were studied by SQUID magnetometer and Mossbauer spectroscopy. From the main peak intensity of XRD and absorption rate of Mossbauer spectrum, the amounts of $\gamma-Fe_2O_3$ and $\alpha-Fe_2O_3$ in as-prepared sample are about 70% and 30%, respectively. The coercivity (53 Oe) and the saturation magnetization (14 emu/g) are about 20% of those of the bulk $\gamma-Fe_2O_3$. The low value of coercivity and saturation magnetization indicate that the $\gamma-Fe_2O_3$ phase nearly shows the spin glass-like behavior. Analysis of the set of Mossbauer spectrum indicates a distribution of magnetic hyperfine fields due to the particle size distribution yielding 20 nm of average particle size. The magnetic hyperfine parameters are consistent with values reported of bulk $\gamma-Fe_2O_3$ and $alpha-Fe_2O_3$. A quadrupole line on the center of spectrum represents of superparamagnetic phase of $\gamma-Fe_2O_3$ with a mean particle size of 7 nm or below.

• 한국통신학회논문지
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• 제37A권11호
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• pp.943-951
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• 2012

본 논문에서는 비정규 충격성 잡음 환경에서 협력 무선인지 네트워크를 위한 순서 기반 스펙트럼 센싱 기법을 제안한다. 구체적으로는 잡음을 이변수 등방형 대칭 알파 안정 (bivariate isotropic symmetric ${\alpha}$-stable) 분포를 따르는 것으로 모형화하고, 그에 알맞은 관측 샘플의 순서와 일반화된 우도비 검정 기반 협력 스펙트럼 센싱 기법을 제안한다. 모의실험을 통해 비정규 잡음 환경에서 제안한 기법이 기존의 기법에 비해 더 좋은 스펙트럼 센싱성능을 가짐을 보인다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 추계종합학술대회
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• pp.170-174
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• 2007

뇌파에 관한 연구는 의학 및 공학 분야에서 많이 활성화 되어 있지만, 침구학에서의 뇌파분석에 과한 연구는 아직 많이 이루어져야 할 부분 중 하나이다. 그러므로 본 연구는 침구요법 중 간접 뜸 자극에 의한 뇌파를 분석하고 자율신경계와의 상관관계를 분석을 하고자 한다. 본 연구의 실험은 간접 쑥 뜸을 인체의 중완, 신궐, 관원의 경혈 점에 자극하고, 자극 전, 자극 중, 자극 후 1시간, 그리고 자극 후 2시간 일 때의 뇌파를 측정한다. 그리고 측정된 데이타는 Matlab 7.0을 이용하여 FFT 및 주파수 파워 스펙트럼을 적용하여 ${\alpha}$, ${\beta}$, ${\delta}$, ${\theta}$파 성분을 자극 단계별로 나누어 주파수 각 성분 비율의 변화, 그리고 진폭의 크기변화량에 대하여 분석 고찰하였다. 본 연구의 결과, EEG 데이터를 FFT를 적용하여 ${\alpha}$, ${\beta}$, ${\delta}$, ${\theta}$파의 비율을 분석한 결과 ${\alpha}$파가 자극 전보다 자극 후 약 2배 정도 증가하는 것을 알 수 있었다. 그리고 전체의 파워스펙트럼 분석에서 ${\alpha}$파, ${\beta}$파의 에너지가 전체적으로 감소하므로 부교감신경이 활성화됨을 알 수 있었다. 본 연구와 기존 연구의 결과를 비교해 보면, 간접 뜸 자극은 자율신경계의 변화에 영향을 줄 수 있으며 ${\alpha}$파의 비율적 증가로 긴장 상태나 스트레스 상태의 사람에게 안정을 가져다 줄 수 있음을 확인 할 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제7권1호
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• pp.39-41
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• 1986

The polycrystalline epr spectrum of ${\alpha}-1,\;2-[PV(IV)VW_{10}O_{40}]^{6-}$ doped into host crystals and its solution spectrum are reported. The solution spectrum consists of fifteen lines, indicating that the unpaired electron is hopping fast between the two vanadium atoms. The polycrystalline spectrum, which consists of three sets of fifteen lines, was analyzed as a spectrum of an I = 7 system and the epr parameters were determined. The spectrum cannot be interpreted by assuming that each line appears at the average magnetic field of two hyperfine lines expected for two uncoupled vanadium atoms.

• East Asian mathematical journal
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• 제21권1호
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• pp.61-64
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• 2005

Let R be a commutative ring with identity, and let $f,\;g_i(i=1,\;\ldots,\;n),\;g_{\alpha}(\alpha{\in}S)$ be elements of R. We show that the following statements are equivalent; (i) $X_f{\subseteq}{\cup}_{\alpha{\in}S}X_{g\alpha}$ only if $X_f{\subseteq}X_{g\alpha}$ for some $\alpha{\in}S$, (ii) $V(f){\subseteq}{\cup}_{\alpha{\in}S}V(g_{\alpha})$ only if $V(f){\subseteq}V(g_{\alpha})$ for some $\alpha{\in}S$, (iii) $V(f){\subseteq}{\cup}^n_{i=1}V(g_i)$ only if $V(f){\subseteq}V(g_i)$ for some i, (iv) Spec(R) is linearly ordered under inclusion.

• Korean Journal of Acupuncture
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• 제28권3호
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• pp.85-98
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• 2011

Objectives : The aim of this thesis is to examine the effect of acupuncture treatment at the GB37 on normal humans by using the power spectral analysis of the EEG. Methods : EEG (Electroencephalogram) power spectrum exhibits site-specific and state-related differences in specific frequency bands. In this thesis, the power spectrum was measured by the complexity. the 32 channels EEG study was carried out in the 13 subjects (12 males ; age=22.58 years old, 1 females ; 22 years old). Results : In the ${\alpha}$ (alpha) band, the power values at F7, F3, F4, F8, FTC2, C4, T4, CP1, CP2, TCP2, TT2, Pz, P4, Po1, Po2, O1, Oz, O2 channels (p<0.05) during the GB37-acupoint treatment were significantly changed. And in many channels were decreased. In the ${\beta}$ (beta) band, the power values at Cz, C4, T4, Tcp1, T6, Po1, O1, Oz, O2 channels (p<0.05) during the GB37-acupoint treatment were significantly changed. And in many channels were decreased. In the ${\delta}$(delta) band, the power values at Fp1, TT2 channels (p<0.05) during the GB37-acupoint treatment were significantly changed. And in many channels were decreased. In the $\theta$ (theta) band, the power values at Fp1, F8, FTC2, Pz channels (p<0.05) during the GB37-acupoint treatment were significantly changed. And in many channels were decreased. Conclusions : This results suggest that the acupuncture treatment at the GB37 significantly mostly change the power spectrum value on the alpha (18 channels), beta (9 channels) bands.

• 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.

• Journal of Microbiology and Biotechnology
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• 제2권2호
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• pp.115-121
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• 1992

In order to broaden the spectrum of substrate utilization of a Gram negative bacterium Zymomonas mobilis which has a great potential as an industrial ethanol producing microorganism, cloning of $\alpha$-amylase gene into Z. mobilis ZM4 was tried. The $\alpha$-amylase gene was isolated from Bacillus stearothermophilus. By Southern blot analysis, it was proven that the $\alpha$-amylase gene fragment was originated from a naturally occuring plasmid of B. stearothermophilus ATCC 31195. To place $\alpha$-amylase gene under the control of Z. mobilis promoter, two different Z. mobilis expression vectors, pZA26 and pLOI204, were used. The truncated $\alpha$-amylase gene was then introduced into these vectors. Both qualitative and quantitative activities of $\alpha$-amylase were observed in Z. mobilis cells harboring these plasmids with the $\alpha$-amylase gene inserted. Gas chromatographic analysis of ethanol showed that one of the Z. mobilis transconjugants was capable of producing 67 mM ethanol from rich medium(RM) containing 5% soluble starch as a sole carbon source.

• 천문학회지
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• 제47권4호
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• pp.147-152
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• 2014

We present measurements of the Fe $K{\alpha}$ emission line of the intermediate polar V1223 Sagittarii observed with the Suzaku satellite. The spectrum is modeled with an absorbed thermal bremsstrahlung spectrum and three Gaussians for the three components of the Fe $K{\alpha}$ lines. We resolve the neutral or low-ionized (6.41keV), He-like (6.70keV), and H-like (7.00keV) iron lines. We also obtain a thermal continuum temperature of 25 keV, which supports a thermal origin of the hard X-rays observed from the shock heated layers of gas between the white dwarf and the shock front. Hence, we believe that the He-like and H-like lines are from the collisional plasma. On the origin of the Fe $K{\alpha}$ fluorescence line, we find that it could be partly from reflections of hard X-rays from the white dwarf surface and the $N_H$ absorption columns. We also discuss the Fe $K{\alpha}$ emission line as veritable tool for the probe of some astrophysical sites.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제5권2호
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• pp.109-114
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• 1998

Let H be a separable complex H be a space and let (equation omitted)(H) be the *-algebra of all bounded linear operators on H. An operator T in (equation omitted)(H) is said to be p-hyponormal if ($T^{\ast}T)^p - (TT^{\ast})^{p}\geq$ 0 for 0 ＜ p ＜ 1. If p = 1, T is hyponormal and if p = $\frac{1}{2}$, T is semi-hyponormal. In this paper, by using a technique introduced by S. K. Berberian, we show that the approximate point spectrum $\sigma_{\alpha p}(T) of a pure p-hyponormal operator T is empty, and obtains the compact perturbation of T.