• The Journal of the Acoustical Society of Korea
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• v.35 no.1
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• pp.8-15
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• 2016

As a generalized form of the conventional Fourier transform, fractional Fourier transform (FrFT) can analyze a signal at intermediate domain between time and frequency domains with a transform order ${\alpha}$. Especially, FrFT has a number of advantages in the analysis of LFM (Linear Frequency Modulation) signals due to its robustness to noise. In this paper, we have proposed a new method to detect and estimate the distance of the target from the FrFT spectrum of the received echo signal. Experimental results have validated the proposed method, and shown that reliable target distance could be estimated in noise and reverberation environments.

• Journal of Microbiology and Biotechnology
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• v.15 no.6
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• pp.1250-1257
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• 2005

Two groups of exopolysaccharides (designated as Fr-I EPS and Fr-II EPS) were isolated from the culture filtrate of new fungal strain Trichoderma erinaceum DG-312 by Sepharose CL-6B chromatography. The structures of the exopolysaccharides were investigated using gas chromatography (GC), Fourier transform-infrared (FT-IR) spectroscopy, GCMS analysis, and NMR. GC analysis indicated that Fr-I EPS was composed of mainly mannose ($78.9\%$) and galactose ($21.1\%$), whereas Fr-II EPS contained mannose ($68.4\%$), galactose ($26.2\%$), and glucose ($5.4\%$). In the anomeric region ($950-700cm_{-1}$) of the FT-IR spectrum, both EPSs exhibited obvious characteristic absorption of $810\;cm_{-1}$, indicating the existence of mannose. The spectra of $\alpha-and\;\beta$-configurations were assigned at 880 and $914\;cm_{-1}$, respectively. The results of GC-MS analyses confirmed that both EPSs were complex heteropolysaccharides with a ($1{\rightarrow}3$)-linked mannan backbone. The C-1 region that appeared in the $^{13}C-NMR$ spectra of these EPSs indicated a typical anomeric carbon signal. The Fr-I EPS showed two anomeric carbon signals at 102.6 and 99.6 ppm, whereas the Fr-II EPS displayed four anomeric carbon signals at 102.5, 99.6, 98.5, and 94.3 ppm. The molecular characteristics of the EPSs were further investigated using a size exclusion chromatography/multi-angle laser light scattering (SEC/MALLS) system. The SEC/MALLS system revealed that the average molar masses of the EPSs were $6.592{\times}10^{4}$ (Fr-I EPS) and $1.920{\times}10^{4}$ (Fr-II EPS) g/mol, and the molecular conformation of both EPSs in aqueous solution was random coils.

• Journal of fish pathology
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• v.19 no.2
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• pp.119-126
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• 2006

The characteristics of the extracellular products (ECPs) of Vibrio harveyi grown under various conditions were studied. The extracellular products (ECPs) of Vibrio harveyi is well known as an important pathogenic factor. The optimal isolation condition of the V. harveyi ECPs was incubation with 1.5% NaCl added TSA medium at 25℃ for 24 h. The buffer system for ECPs isolation controlled as pH 8.0 displayed optimal condition. The major protein of ECPs isolated from the five V. harveyi strains originated from Korea (FF8, FF10, FR1, FR2 and FT1 strain) were revealed to serine protease.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.2
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• pp.195-206
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• 2022

The separation of spectrally overlapped broadband echo signals from free-swimming Japanese needlefish Hypohamphus sajori using the fractional Fourier transform (FrFT) was investigated. The broadband echo signals were measured over frequency ranges of 40-80 and 110-220 kHz. The overlapped echo signals were separated after eliminating noise signals in the smoothed pseudo-Wigner-Ville distribution domain. The echo signal from a 40 mm WC sphere suspended just below a chirp transducer was used to calibrate the broadband of the chirp echo sounder and estimate the frequency dependence of target strength for the separated echo signals. The experimental results show that the proposed FrFT method can analyze the time-frequency image of broadband echo signals from free-swimming individual fish effectively and can be used as a quantitative tool for extracting the acoustic features used for fish species identification.

• Journal of Microbiology and Biotechnology
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• v.19 no.9
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• pp.951-959
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• 2009

Most, if not all, Basidiomycetes mushrooms have biologically active polysaccharides showing potent antitumor activity with immunomodulating properties. These polysaccharides have various chemical compositions and belong primarily to the $\beta$-glucan group. In this study, the crude water-soluble polysaccharide HEF-P, which was obtained from the fruiting body of Hericium erinaceus by hot water extraction and ethanol precipitation, was fractionated by DEAE-cellulose and Sepharose CL-6B column chromatographies. This process resulted in four polysaccharide fractions, named HEF-NP Fr I, HEF-NP Fr II, HEF-AP Fr I, and HEF-AP Fr II. Of these fractions, HEF-AP Fr II was able to upregulate the functional events mediated by activated macrophages, such as production of nitric oxide and expression ofcytokines (IL-1${\beta}$ and TNF-${\alpha}$). The molecular mass of HEF-AP Fr II was estimated by gel filtration to be 13 kDa. Its structural characteristics were investigated by a combination of chemical and instrumental analyses, including methylation, reductive cleavage, acetylation, Fourier transform infrared spectroscopy (FT-IR), and gas chromatography-mass spectrometry (GC-MS). Results indicate that HEF-AP Fr II is a low-molecular-mass polysaccharide with a laminarin-like triple helix conformation of a ${\beta}$-1,3-branched-${\beta}$-1,6-glucan.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.171-191
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• 2005

This Technical Memo(TM) was written for the purpose of determining the type of UHF-band power divider which is applicable to KSLV-1. For this, some different kinds of power divider are compared with there types and characteristics. And then, we select three types of power divider(which is Wilkinson power divider, Quadrature hybrid divider and Ring hybrid divider) and perform Schematic and Momentum simulation for finding the optimized characteristics. With this results, in order to demonstrate the selected power divider, we manufactured UHF-band power dividers using FR-4 epoxy plate. By the measured results, we obtain the similar results compare with simulation and fabrication. And Quadrature hybrid power divider is suitable to application to KSLV-1.

• Textile Coloration and Finishing
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• v.15 no.4
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• pp.24-31
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• 2003

In this research, we applied FT-IR spectroscopy to study the hydrolysis of the ester-crosslinking formed by various polycarboxylic acids on the cotton fabric. We observed the following; (1) the ester-crosslinking is less durable to hydrolysis than ether-crosslinking under all conditions; (2) the ester-crosslinking formed by polycarboxylic acids having more than three carboxyl groups, such as butanetetracarboxylic acid (BTCA), are substantially more durable to hydrolysis than the acids having two or three carboxyl groups, such as maleic and citric acid; (3) alkaline conditions drastically accelerate the hydrolysis of both urea- and ester-crosslinking; and (4) the ester-crosslinking formed by poly(maleic acid) is more resistant to hydrolysis at alkaline conditions than BTCA. (5) polycarboxylic acid molecules were removed from the fabric at same rate as the hydrolysis of the ester linkage. FT-IR spectroscopy has proved to be a useful analytical technique for evaluating the hydrolysis of the crosslinked cotton fabric.

• The Korean Journal of Food And Nutrition
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• v.25 no.4
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• pp.968-973
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• 2012

This study analyzes the structure types of salmon oil to evaluate the purity of salmon oil products based on the 38 different types of imported salmon oil products distributed in the Republic of Korea. The major types of omega-3 foods in the salmon oil are ethyl ester (EE) and triglyceride (TG). If the salmon oil contained potential contaminants and was processed in order to remove it, EE type omega-3 fatty acids are found in concentration. This provides a good guide in assessing if products were made with EE type ingredients or re-esterified contaminated materials. The results of the FT-IR analysis showed significant difference in the C=O, C-O band positions in TG and EE. There were 19 TG type products and 19 EE type products. The analysis of carbon isotope ratio was performed on the types of TG and EE. There were different properties in the 19 TG type products. In one product, the carbon isotope ratio was -25.15 and the other 18 products showed -22.15~-23.96. The carbon isotope ratio of all 19 EE type products showed -21.91~-23.74. The results of the TLC analysis showed similar results with FR-IR. The re-esterified TG form was not detected in the TG type products, confirming that the TG type products contained natural salmon oil. This study aimed to provide the basic material in classifying the types of natural salmon oil and re-esterified salmon oil, by analyzing the pattern and proportion of FT-IR spectrum, carbon isotope ratio, and TLC.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.3
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• pp.418-424
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• 2018

Detection and classification of underwater targets is an important issue for both military and non-military purposes. Recently, many performance improvements are being reported in the field of pattern recognition with the development of deep learning technology. Among the results, DBN showed good performance when used for pre-training of DNN. In this paper, DBN was used for the classification of underwater targets using active sonar, and the results are compared with that of the conventional BPNN. We synthesized active sonar target signals using 3-dimensional highlight model. Then, features were extracted based on FrFT. In the single aspect based experiment, the classification result using DBN was improved about 3.83% compared with the BPNN. In the case of multi-aspect based experiment, a performance of 95% or more is obtained when the number of observation sequence exceeds three.

• Journal of Life Science
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• v.29 no.6
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• pp.662-670
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• 2019

The purpose of this study was to investigate the effect of methanolic extracts of graviola, Annona muricate leaves (AMME) on antioxidant activity and melanin production. First of all, DPPH radical and reducing power were performed to determine the antioxidant effect of AMME and organic solvent fractions. AMME and organic solvent fractions showed antioxidative activity in a concentration dependent manner. The ethyl acetate fraction of AMME among organic solvent fractions showed the highest antioxidant activity. Moreover, tyrosinase activity was performed to confirm the effect of organic fractions on melanin production. AMME, ethyl acetate, and hexane fractions increased tyrosinase activity a dose dependent manner. Next, the hexane fraction with the best effect on melanin synthesis in AMME organic solvent fraction was divided into 12 fractions by silica column chromatography. Among them, the fraction 7 and 8 showed the highest DPPH radical scavenging activity and reducing power. In addition, the fraction 7 and 8 at $64{\mu}g/ml$ showed melanin synthesis by 260% and 184%, respectively. Finally, the fraction 8 at $4{\mu}g/ml$ showed melanin synthesis by 34% in B16F1 cells. LC-MS analysis showed that fraction 7 and fraction 8 have a molecular weight of 617 and 619, respectively. FT-IR analysis showed that fractions 7 and 8 is similar to bis(2-hydroxyethly)dimerate. Above results suggest that graviola leaves extracts could be applicable to the development of natural antioxidants or hair cosmetics which are related to the promoting effect of melanin production.