• ETRI Journal
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• 제36권5호
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• pp.721-729
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• 2014

We propose a novel phase-based method for single-channel speech enhancement to extract and enhance the desired signals in noisy environments by utilizing the phase information. In the method, a phase-dependent a priori signal-to-noise ratio (SNR) is estimated in the log-mel spectral domain to utilize both the magnitude and phase information of input speech signals. The phase-dependent estimator is incorporated into the conventional magnitude-based decision-directed approach that recursively computes the a priori SNR from noisy speech. Additionally, we reduce the performance degradation owing to the one-frame delay of the estimated phase-dependent a priori SNR by using a minimum mean square error (MMSE)-based and maximum a posteriori (MAP)-based estimator. In our speech enhancement experiments, the proposed phase-dependent a priori SNR estimator is shown to improve the output SNR by 2.6 dB for both the MMSE-based and MAP-based estimator cases as compared to a conventional magnitude-based estimator.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2004년도 Annual Meeting BioExibition International Symposium
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• pp.258-265
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• 2004

Numerous genes of Escherichia coli have been shown to growth phase-dependent expression throughout growth. The global patterns of growth phase-dependent gene expression of E. coli throughout growth using oligonucleotide microarrays containing a nearly complete set of 4,289 annotated open reading frames. To determine the change of gene expression throughout growth, we compared RNAs taken from timecourses with common reference RNA, which is combined with equal amount of RNA pooled from each time point. The hierarchical clustering of the conditions in accordance with timecourse expression revealed that growth phases were clustered into four classes, consistent with known physiological growth status. We analyzed the differences of expression levels at genome level in both exponential and stationary growth phase cultures. Statistical analysis showed that 213 genes are shown to, growth phase-dependent expression. We also analyzed the expression of 256 known operons and 208 regulatory genes. To assess the global impact of RpoS, we identified 193 genes coregulated with rpoS and their expression levels were examined in the isogenic rpoS mutant. The results revealed that 99 of 193 were novel RpoS-dependent stationary phase-induced genes and the majority of those are functionally unknown. Our data provide that global changes and adjustments of gene expression are coordinately regulated by growth transition in E. coli.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제25권4호
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• pp.345-355
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• 2018

This paper looks into phase plane behavior of the solution near the positive steady-state for the system with prey density dependent response functions. The positive invariance and boundedness property of the solution to the objective model are proved. The existence result of a positive steady-state and asymptotic analysis near the positive constant equilibrium for the objective system are of interest. The results of phase plane analysis for the system are proved by observing the asymptotic properties of the solutions. Also some numerical analysis results for the behaviors of the solutions in time are provided.

• Journal of the Korean Physical Society
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• 제73권11호
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• pp.1729-1734
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• 2018

Organic-inorganic halide perovskite single crystals undergo phase transition of being cubic, tetragonal, or orthorhombic depending on the temperature. We investigated the $CH_3NH_3PbBr_{3-x}I_x$ single crystals grown by the inverse temperature crystallization method with temperature-dependent UV-Vis absorption and photoluminescence. From the temperature-dependent absorption measurement, the optical band gap is extracted by derivation of absorption spectrum fitting and Tauc plot. In our results, $CH_3NH_3PbBr_{3-x}I_x$ single crystals show that an abrupt change in optical band gap, PL peak position and intensity appears around 120 K - 170 K regions, indicating the phase transition temperature.

• Steel and Composite Structures
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• 제38권4호
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• pp.355-363
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• 2021

The present paper attempts to investigate the propagation of plane waves in an isotropic elastic medium under the effect of initial stress and temperature-dependent properties. The modulus of elasticity is taken as a linear function of the reference temperature. The formulation is applied under the thermoelasticity theory with dual-phase-lag; the normal mode analysis is used to obtain the expressions for the displacement components, the temperature, the stress, and the strain components. Numerical results for the field quantities are given in the physical domain and illustrated graphically. Comparisons are made with the results predicted by different theories (Lord-Shulman theory, the classical coupled theory of thermoelasticity and the dual-phase-lag model) in the absence and presence of the initial stress as well as the case where the modulus of elasticity is independent of temperature.

• Geomechanics and Engineering
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• 제28권4호
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• pp.347-358
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• 2022

The main concern of this article is to discuss the problem of a two-temperature fiber-reinforced micropolar thermoelastic medium with voids under the effect rotation, mechanical force in the context four different theories with memory-dependent derivative (MDD) and variable thermal conductivity. The three-phase-lag model (3PHL), dual-phase-lag model (DPL), Green-Naghdi theory (G-N II, G-N III), coupled theory, and the Lord-Shulman theory (L-S) are employed to solve the present problem. Analytical expressions of the physical quantities are obtained by using Laplace-Fourier transforms technique. Numerical results are shown graphically and the results obtained are analyzed. The most significant points are highlighted.

• 대한의용생체공학회:의공학회지
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• 제20권2호
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• pp.165-172
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• 1999

본 연구에서는 MRI 영상에서 위상을 조절하여 영상 대조를 증가 시키는 방법을 제안 하였다 영상하고자 하는 물체 자체가 갖는 위상에 따라 영상의 대조가 변하기 때문에 본 방법은 자화율 영상이나 유속 영상에 유용하게 쓰일 수가 있다. 본 논문에서는 위상 분포에 따른 영상의 대조를 증가 시키기 위하여 RF 펄스를 복셀 내에서 위상을 갖도록 디자인 하였다. 따라서 복셀에서의 신호의 크기는 물체자체의 위상과 RF 펄스에의하여 가해준 위상이 결합에 의하여 결정된다. 외부위상 변화에 따른 신호의 변화를 분석하였고 그때 디자인된 RF 펄스를 이용하여 자화율만의 영상과 유속만의 영상을 얻었다. 컴퓨터 시뮬레이션의 결과는 제안된 알고리즘이 복셀내에 위상을 갖는 물체의 영상에 유용하고 그런 물체만을 영상하는데 유용함을 보였다.

• Archives of Pharmacal Research
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• 제17권4호
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• pp.226-230
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• 1994

The characteristics of voltage-dependent ^{45}Calcium$ uptake and norepinephrine release as factors controlling neural activities in the hypothalamus which is an important regulatory site for cardiovascular function wre studied. Two groups of animals : male spontaneously hyperterisive rat (SHR) and age-matched nomotensive wistar rat (NW) were used in this study. Animals at 4, 6 and 16 weeks of age were sacrificed by decapitiation and the hypothalamus was dissected out. Voltage-dependent calcium uptake and norepinephrine release were determined from hypothalamic synaptosomes either in low potassium (5 mM) or high potassium (41 mM) stimulatory conditions by using ^{45}Ca$ isotope and HPLC-ECD techniques. Degrees of voltage-dependent ^{45}Calcium$ uptake and norepinephrine release evoked by calcium uptake in the hypothalamus of prehypertensive phase (4 weeks old) of SHR were significantly smaller than those in NW of the same age. However, in the developmental phase (6 weeks old) and the established phase (16 weeks old) of hyperrtension in SHR, degrees of voltage-dependent ^{45}Calcium$ uptake and norepinephrine release were similar to those of age-matched normotensive wistae eats. These data imply that the deficit in hypothalamic norepinephrine release might be an important underlying factor for the development of hypertension in SHR.

• 전기의세계
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• 제23권5호
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• pp.54-60
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• 1974

Proposals were mode on how to differentiate radiation effects in morphological phases of polyethylene and discussions were developed with the results obtained on a low density polyethylene, SOCAREX, specified by number average molecular weight; overbar Mn=5,400, density; 0.92, and degree of branch; 3.4/100 carbon atom, which was irradiated to Co$^{60}$ .gamma. ray at the dose rate of 0.5 Mrad/hr in ambient temperature under the pressure of 10$^{-5}$ Torr. or 1 atm. respectively. The effect to crystalline phase in possibly deduced from dose dependent variation of relative area between (110) and (200) peaks on X ray diffraction spectrum and that, the effects to amorphous phase can be understood through dose dependent relaxation behaviours of .betha. peak on internal friction characteristics of the specimen. The results obtained thus far indicate that, in crystalline phase, relative crystallinity shows a rather rapid decrease up to 20 Mrad with increasing dose, however, little change of crystallinity can be observed in the region between 20-200 Mrad, and degradation appears to be more predominant than crosslinking up to 60 Mrad. While in amorphous phase the indication also shows that degradation is only predominant up to 20 Mrad. Furthermore several correlations can be seen with amenable explanation between dose dependent behaviours observed in both phases.

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.895-898
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• 2014

The wavelength dependence of the photoacoustic signal for n-type GaAs semiconductors in the region of the band-gap energies was investigated. The significant changes in the phase and amplitude of the photoacoustic signal near the band-gap absorption wavelengths were observed to occur when the Si-doping densities in GaAs were varied. Particularly, the first derivatives of the photoacoustic phase vs. wavelength graphs were evaluated and fitted with single Gaussian functions. The peak centers and the widths of the Gaussian curves clearly showed linear relationships with the log values of the Si-doping densities in n-type GaAs semiconductors. It is proposed that the wavelength-dependent PA spectroscopy can be used as a simple and nondestructive method for measuring the doping densities in bulk semiconductors.