• Current Optics and Photonics
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• v.5 no.3
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• pp.278-288
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• 2021

We propose a characterization method for the scattering property of microspheres using spectroscopic optical coherence tomography (OCT). To prove the effectiveness of the proposed method, we prepare solutions of different concentrations using microspheres ranging from 28 to 2300 nm in diameter. Time-frequency analysis is performed on the measured interference spectrum of each solution, and the resulting spectroscopic information is converted into histograms for centroid wavelengths. The histograms present a very sensitive response to changes in the concentration and size of microspheres. We classify them into three categories according to their characteristics. When the histogram of each category is replaced with the corresponding calculated value of the scattering coefficient, each category is mapped to a different scattering-coefficient region. It is expected that the proposed method could be used to investigate the optical characteristics of a biological sample from OCT images, which would be helpful for optical diagnostic and therapeutic applications.

• Communications of the Korean Mathematical Society
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• v.38 no.3
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• pp.663-677
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• 2023

The purpose of this paper is to introduce a new class of rings containing the class of SFT-rings and contained in the class of rings with Noetherian prime spectrum. Let A be a commutative ring with unit and I be an ideal of A. We say that I is SFT if there exist an integer k ≥ 1 and a finitely generated ideal F ⊆ I of A such that x^k ∈ F for every x ∈ I. The ring A is said to be nonnil-SFT, if each nonnil-ideal (i.e., not contained in the nilradical of A) is SFT. We investigate the nonnil-SFT variant of some well known theorems on SFT-rings. Also we study the transfer of this property to Nagata's idealization and the amalgamation algebra along an ideal. Many examples are given. In fact, using the amalgamation construction, we give an infinite family of nonnil-SFT rings which are not SFT.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.161-167
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• 2009

Organic insulating materials which are utilized as insulating materials for the low voltage show unique carbonization characteristics when they are carbonized by a leakage current. Therefore the use of the carbonization characteristics makes it possible to examine the electrical fire which is caused by a leakage current flowing on the surface of the organic insulating material. In order to understand such carbonization characteristics, in this paper, experiments have been done to carbonize typical organic insulating materials such as phenol resin, PVC, and acrylic resin, and the carbonization patterns and the IR absorption spectrum of specimens have been analyzed. According to the analysis of the carbonization patterns, the phenol resin shows the so-called 'spider-leg' carbonization pattern due to a thermosetting property. In contrast to the phenol resin, the thermoplastic property makes it difficult to observe a clear carbonization pattern to verify carbonizing causes on the surfaces of PVC and acrylic resins. In this case, the IR absorption spectrum can be analyzed to examine the specimen carbonized by a leakage current. The analysis result shows that absorption peaks appear at the wave numbers of $3,400[cm^{-1}]$ and $1,618[cm^{-1}]$, which can be an important factor to verify the carbonizing causes.

• Journal of the Institute of Convergence Signal Processing
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• v.4 no.2
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• pp.18-24
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• 2003

One of the most important subjects in the implementation of real time speech recognizer is to design both reliable VAD(Voice Activity Detection) and suitable speech feature vector. But, because it is difficult to calculate reliable VAD in the environment having surrounding noise, designed suitable speech feature vector may not be obtained. Solving this problem, in this paper, we implement not only short time power spectrum which is generally used but also two additive parameters, the comparison measure of spectrum density having robust property in noise and linear discriminant function using linear regression, then perform VAD by using the combination of each parameter having apt weight in other magnitudes of surrounding noise and confirm that proposed parameters show a robust characteristic in circumstances having surrounding noise by using DTW(Dynamic Time Waning) in recognition experiment.

• Journal of the Korean Chemical Society
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• v.42 no.1
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• pp.42-50
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• 1998

Titanium dioxide $(TiO_2)$ thin film samples were prepared by using spray pyrolysis methodology and were by using X-ray photoelectron spectroscopy and X-ray diffraction analysis. It was found that anatase prepared by the hydrolysis of titanium(Ⅳ) oxyacetylacetonate exhibited the largest specific surface area. The particle size increased with increasing temperature, while the thickness decreased. Titanium dioxide $(TiO_2)$ in the anatase form was prepared at $400^{\circ}C$ and the photoconductivity was determined using photocurrent measurements. Photoelectrochemical properties of the $TiO_2$-phthalocyanine system were measured in a three-electrode system. The photocurrent action spectrum in the visible region coincided with intrinsic absorption spectrum of phthalocyanine. The crystal structure of phthalocyanine is considered to be a very important property in the photogeneration phenomena.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.1
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• pp.52-58
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• 2013

The effets of the pretreatments of tropical kapok fibers were evaluated in this study in terms of water sorption capacity and oil sorption capacity. The alkali treatments with NaOH resulted in the reduction of lignin, oil and hemicellulose, which were detected with FT-IR spectrum. The reduction of the lyphophilic components such as fat on kapok fiber by the ozone treatments were also measured with FT-IR spectrum. The oil sorption capacity of kapok fiber was decreased by the alkali treatments and the ozone treatments, while the water sorption capacity was increased. The liquid sorption capacity were greatly affected by the mechanical cutting of kapok fiber which exposed the big lumen of kapok fiber. The hydrophilic property of kapok fiber could be controlled by the pretreatments, which would increase the applicability of kapok fiber for preparation of various functional paper products.

• Clinical and Experimental Pediatrics
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• v.56 no.6
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• pp.235-241
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• 2013

Repair of tetralogy of Fallot (TOF) has shown excellent outcomes. However it leaves varying degrees of residual hemodynamic impairment, with severe pulmonary stenosis (PS) and free pulmonary regurgitation (PR) at both ends of the spectrum. Since the 1980s, studies evaluating late outcomes after TOF repair revealed the adverse impacts of residual chronic PR on RV volume and function; thus, a turnaround of operational strategies has occurred from aggressive RV outflow tract (RVOT) reconstruction for complete relief of RVOT obstruction to conservative RVOT reconstruction for limiting PR. This transformation has raised the question of how much residual PS after conservative RVOT reconstruction is acceptable. Besides, as pulmonary valve replacement (PVR) increases in patients with RV deterioration from residual PR, there is concern regarding when it should be performed. Regarding residual PS, several studies revealed that PS in addition to PR was associated with less PR and a small RV volume. This suggests that PS combined with PR makes RV diastolic property to protect against dilatation through RV hypertrophy and supports conservative RVOT enlargement despite residual PS. Also, several studies have revealed the pre-PVR threshold of RV parameters for the normalization of RV volume and function after PVR, and based on these results, the indications for PVR have been revised. Although there is no established strategy, better understanding of RV mechanics, development of new surgical and interventional techniques, and evidence for the effect of PVR on RV reverse remodeling and its late outcome will aid us to optimize the management of TOF.

• Journal of Ginseng Research
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• v.35 no.4
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• pp.487-496
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• 2011

Good manufacturing practice (GMP)-based quality control is an integral component of the common technical document, a formal documentation process for applying a marketing authorization holder to those countries where ginseng is classified as a medicine. In addition, authentication of the physico-chemical properties of ginsenoside reference materials, and qualitative and quantitative batch analytical data based on validated analytical procedures are prerequisites for certifying GMP. Therefore, the aim of this study was to propose an authentication process for isolated ginsenosides $Rb_1$ and $Rg_1$ as reference materials (RM) and for these compounds to be designated as RMs for ginseng preparations throughout the world. Ginsenoside $Rb_1$ and $Rg_1$ were isolated by Diaion HP-20 adsorption chromatography, silica gel flash chromatography, recrystallization, and preparative HPLC. HPLC fractions corresponding to those two ginsenosides were recrystallized in appropriate solvents for the analysis of physico-chemical properties. Documentation of the isolated ginsenosides was made according to the method proposed by Gaedcke and Steinhoff. The ginsenosides were subjected to analyses of their general characteristics, identification, purity, content quantitation, and mass balance tests. The isolated ginsenosides were proven to be a single compound when analyzed by three different HPLC systems. Also, the water content was found to be 0.940% for $Rb_1$ and 0.485% for $Rg_1$, meaning that the net mass balance for ginsenoside $Rb_1$ and $Rg_1$ were 99.060% and 99.515%, respectively. From these results, we could assess and propose a full spectrum of physicochemical properties for the ginsenosides $Rb_1$ and $Rg_1$ as standard reference materials for GMP-based quality control.

• The Journal of the Acoustical Society of Korea
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• v.21 no.7
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• pp.665-670
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• 2002

The most common form of pre-emphasis is y(n)=s(n)-As(n-1), where A typically lies between 0.9 and 1.0 in voiced signal. Also, this value reflects the degree of pre-emphasis and equals R(1)/R(0) in conventional method. This paper proposes a new flattening method to compensate the weaked high frequency components that occur by vocal cord characteristic. We used interval information of LSP to estimate formant frequency, After obtaining the value of slope and inverse slope using linear interpolation among formant frequency, flattening process is followed. Experimental results show that the proposed method flattened the weaked high frequency components effectively. That is, we could improve the flattening characteristics by using interval information of LSP as flattening factor at the process that compensates weaked high frequency components.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.38.2-38.2
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• 2016

The mapping of dark matter clustering from real to redshift spaces introduces the anisotropic property to the measured density power spectrum in redshift space, known as the Redshift Space Distortion (hereafter RSD) effect. The mapping formula is intrinsically non-linear, which is complicated by the higher order polynomials due to the indefinite cross correlations between the density and velocity fields, and the Finger-of-God (hereafter FoG) effect due to the randomness of the peculiar velocity field. Furthermore, the rigorous test of this mapping formula is contaminated by the unknown non-linearity of the density and velocity fields, including their auto- and cross-correlations, for calculating which our theoretical calculation breaks down beyond some scales. Whilst the full higher order polynomials remains unknown, the other systematics can be controlled consistently within the same order truncation in the expansion of the mapping formula, as shown in this paper. The systematic due to the unknown non-linear density and velocity fields is removed by separately measuring all terms in the expansion using simulations. The uncertainty caused by the velocity randomness is controlled by splitting the FoG term into two pieces, 1) the non-local FoG term being independent of the separation vector between two different points, and 2) the local FoG term appearing as an indefinite polynomials which is expanded in the same order as all other perturbative polynomials. Using 100 realizations of simulations, we find that the best fitted non-local FoG function is Gaussian, with only one scale-independent free parameter, and that our new mapping formulation accurately reproduces the observed power spectrum in redshift space at the smallest scales by far, up to k ~ 0.3 h/Mpc, considering the resolution of future experiments.