• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.667-678
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• 2002

In this paper, a new radiating structure with a multi-layered two-dimensional metallic disk array was proposed for shaping the flat-topped element pattern. It is an infinite periodic planar array structure with metallic disks finitely stacked above the radiating circular waveguide apertures. The theoretical analysis was in detail performed using rigid full-wave analysis, and was based on modal representations for the fields in the partial regions of the array structure and for the currents on the metallic disks. The final system of linear algebraic equations was derived using the orthogonal property of vector wave functions, mode-matching method, boundary conditions and Galerkin's method, and also their unknown modal coefficients needed for calculation of the array characteristics were determined by Gauss elimination method. The application of the algorithm was demonstrated in an array design for shaping the flat-topped element patterns of $\pm$20$^{\circ}$ beam width in Ka-band. The optimal design parameters normalized by a wavelength for general applications are presented, which are obtained through optimization process on the basis of simulation and design experience. A Ka-band experimental breadboard with symmetric nineteen elements was fabricated to compare simulation results with experimental results. The metallic disks array structure stacked above the radiating circular waveguide apertures was realized using ion-beam deposition method on thin polymer films. It was shown that the calculated and measured element patterns of the breadboard were in very close agreement within the beam scanning range. The result analysis for side lobe and grating lobe was done, and also a blindness phenomenon was discussed, which may cause by multi-layered metallic disk structure at the broadside. Input VSWR of the breadboard was less than 1.14, and its gains measured at 29.0 GHz. 29.5 GHz and 30 GHz were 10.2 dB, 10.0 dB and 10.7 dB, respectively. The experimental and simulation results showed that the proposed multi-layered metallic disk array structure could shape the efficient flat-topped element pattern.

• Journal of Ginseng Research
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• v.33 no.2
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• pp.104-110
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• 2009

It is well known that the saponin of Korean red ginseng (KRG) has an anti-oxidant effect and could suppress the accumulation of lipid peroxidation. The aim of the present study was to observe the inhibitory effect of KRG on mice with noise-induced hearing loss, and to determine its optimal dose. BALB/c mice with a normal hearing level and normal Preyer's reflexes were used in the study. The mice in the permanent-threshold-shift (PTS) group were exposed to noise (120-dB SPL, white noise band) in a noise booth for 3 h a day, for three consecutive days. The mice in the experimental group were given heat-processed red-ginseng extract (50 mg/kg, 100 mg/kg, and 200 mg/kg), and those in the control group were given normal saline alone during their noise exposure. The mice in the temporary-threshold-shift (TTS) group were exposed to noise (120 dBSPL, white noise band) in a noise booth for 3 h. The mice in the experimental group were given heat-processed red-ginseng extract (50 mg/kg, 100 mg/kg, and 200 mg/kg), and those in the control group were given normal saline alone before their noise exposure. The hearing levels of the mice were measured through auditory brainstem response (ABR) immediately and I, 3, 5, 7, and 14 days after their noise exposure. Cochleae were removed from the mice 14 days after their noise exposure. lmmunochemical and immunofluorescent staining were performed to observe the expression of 8-oxoG in cochlea. In the PTS group, the hearing function of the mice in all the groups was not recovered after their noise exposure. In the TTS group, however, the hearing function of the mice in all the groups was recovered within 14 days. Reduced hearing impairment and early recovery were observed in the mice that were given 200 mg/kg KRG, and early recovery was observed in the mice that were given 100 mg/kg KRG The immunopositive staining of 8-oxoG was detected in the stria vascularis in the control group but was diminished in the mice that were given 200 mg/kg KRG The ingestion of more than 100 mg/kg KRG demonstrated a protection and recovery effect on the noiseinduced-TTS group. Since KRG has been reported to be a safe compound even up to hundreds of mg/kg, a higher concentration of it may effectively protect and recover TTS.

• Korean Journal of Remote Sensing
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• v.38 no.6_2
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• pp.1691-1707
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• 2022

Cheonji Lake, the caldera of Baekdu Mountain, located on the border of the Korean Peninsula and China, alternates between melting and freezing seasonally. There is a magma chamber beneath Cheonji, and variations in the magma chamber cause volcanic antecedents such as changes in the temperature and water pressure of hot spring water. Consequently, there is an abnormal region in Cheonji where ice melts quicker than in other areas, freezes late even during the freezing period, and has a high-temperature water surface. The abnormal area is a discharge region for hot spring water, and its ice gradient may be used to monitor volcanic activity. However, due to geographical, political and spatial issues, periodic observation of abnormal regions of Cheonji is limited. In this study, the degree of ice change in the optimal region was quantified using a Landsat -5/-7/-8 optical satellite image and a Modified U-Net regression model. From January 22, 1985 to December 8, 2020, the Visible and Near Infrared (VNIR) band of 83 Landsat images including anomalous regions was utilized. Using the relative spectral reflectance of water and ice in the VNIR band, unique data were generated for quantitative ice variability monitoring. To preserve as much information as possible from the visible and near-infrared bands, ice gradient was noticed by applying it to U-Net with two encoders, achieving good prediction accuracy with a Root Mean Square Error (RMSE) of 140 and a correlation value of 0.9968. Since the ice change value can be seen with high precision from Landsat images using Modified U-Net in the future may be utilized as one of the methods to monitor Baekdu Mountain's volcanic activity, and a more specific volcano monitoring system can be built.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.162-168
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• 2010

To increase the energy conversion efficiency of dye sensitized solar cells (DSSCs), it has been widely studied how to effectively transferred the electron generated from the adsorbed dye to the $TiO_{2}$ electrode for avoiding the recombination of injected electrons and iodide ions ($I^-/I_3^-$). For the blocking of the recombination, in this study, $Al_2O_3$-coated $TiO_{2}$ electrode was prepared and applied for DSSCs. In especial, the optimal preparation conditions of $Al_2O_3$ coated onto $TiO_{2}$ porous film was proposed for higher energy conversion efficiency. As a result, the solar cells fabricated from $Al_2O_3$-coated (i.e., particle size of bohemite sol : 100 nm) $TiO_{2}$ electrodes showed superior conversion efficiency (9.0%) compared to the bare $TiO_{2}$ electrodes (7.5%).

• KSBB Journal
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• v.14 no.5
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• pp.578-584
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• 1999

The lectin was purified through 0.15 M NaCl extraction, ammonium sulfate precipitation, sepharose 4B affinity chromatography and gel filtration using sephadex G-150 from the leaves of Visum album collected in Mt. Duk Yu. The final gel filtration step resulted in 11.64 folds purification with 0.14% of recovery yield. We also performed biochemical characterization of the purified Visum album lectin. HPLC analysis of lectin purified by gel filtration revealed a singel peak. The analysis of the purified lectin by SDS-PAGE showed a tetramer composed of two identical subunits with molecular weights of 32 and 30 kDa. The lectin was a glycoprotein containing 14.4% carbohydrate, which consist of glucose, fructose, arabinose and xylose, and the amino acids such as phenylalanine, lysine and tyrosine. The purified lectin agglutinated human red blood cell types with similar potency, but when tested against red blood cells from mouse, bovine, rabbit, chicken and porcine, significant difference in potency were observed. Hemaggluting activity was inhibited by D-galactose, D-mannose, D-lactose and D-raffinose, but not by D-glucose, D-glucosamine, D-mannosamine, L-fructose, D-xylose, D-arabinose, D-galacturonic acid, D-fructose, L-rhamnose and N-acetyl-D-galactosamine. The optimal pH and thermal stability of the purified lectin were pH 4.0-7.0 and 20-5$0^{\circ}C$, respectively.

• Journal of fish pathology
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• v.10 no.2
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• pp.153-164
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• 1997

Characteristics and pathogenicity of Yersinia sp. strain isolated from diseased cultured olive flounder, Paralichthys olivaceous were studied. The causative organisms were identified as Yersinia sp. by biochemical and biophysical characteristics. The strain was named KF-1, and it showed the optimal growth rate at pH 9.0 and 1% NaCl. Total cell protein peptide bands of the Yersinia sp. KF-1 were between 14.4-100.6 Kd in molecular weight by the electrophoretic analysis, and a total of 28 bands appeared. The band found at 32.8 Kd in molecular weight was the major one of electrophoretic phase. In the pathogenicity test of the isolate to the flounder injecting with $1.0{\times}10^7$ cfu/fish 9 died out of 10 within 60 hrs, and in the group with $1.0{\times}10^7$ cfu/fish 5 died within 60 hrs. Thus the $LD_{50}$ was presumed to be $1.0{\times}10^7$ cfu/fish. In the drug sensitivity test KF-1 strain was sensitive to chloramphenicol, gentamycin, kanamycin, streptomycin and pefloxacin, and intermediate to erythromycin, and resistant to ampicillin, cephalothin, sulfamethoxazole/trimethoprim, tetracycline and vancomycin.

• Science of Emotion and Sensibility
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• v.23 no.2
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• pp.3-12
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• 2020

The purpose of this work is to suggest the optimal color temperature, which induces a sense of comfort for autonomous vehicle users through the analysis of biosignal using electroencephalography (EEG) and photoplethysmography (PPG). To achieve this purpose, we applied lighting with a color temperature of 3000 K, 4000 K, 5000 K, and 6000 K to the autonomous driving environment. We experimented in a laboratory equipped with a graphic driving simulator. The experimental procedure is as follows: 1) stabilization (5 min). 2) Uchida-Kraepelin test (3 min). 3) Automatic driving + lighting (3 min). This procedure was repeated four times under different color temperatures. We performed frequency analysis on a collected time-series data and calculated the power value for each frequency band through power spectrum analysis. In the case of EEG, we analyzed α- and β-waves, which are indicators of stability and arousal, respectively. In the case of PPG, we analyzed the sympathetic nervous system activity. To reduce deviations between the subjects, we normalized the data before analysis. The result of the first analysis revealed that α-wave increased only at 5000 K, while the β-wave increased at almost all color temperatures. In addition, in the case of PPG, sympathetic nervous system activity (SNSA) increased under driving conditions. The result of the second analysis revealed that the difference between β-wave and SNSA is insignificant. In conclusion, the increase in α-waves showed that EEG was most stable at 5000 K. The results of this study can be applied to the upcoming autonomous driving era to induce high driver satisfaction. Furthermore, this approach could eventually lead to the acceptance of autonomous vehicles by suggesting a positive effect of autonomous driving.

• Korean Journal of Microbiology
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• v.47 no.1
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• pp.81-86
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• 2011

Xylanase is a class of enzymes that hydrolyze the linear polysaccharide ${\beta}$-1,4-xylan into xylose. This enzyme is applied in the process of paper making and may be used for the process of biofuel production in the future. The Paenibacillus donghaensis JH8, isolated from Donghae deepsea sediment and reported as a novel bacterium, was known to degrade xylan and its xylanase was characterized in this study. The enzyme was maximally induced in the presence of 0.1% xylan. The production of xylanase was started at early logarithmic phase and reached about 55 miliunit at stationary phase of growth. The optimal temperature and pH of extracellular xylanase were found to be $40^{\circ}C$ and pH 6.0, respectively. The activity of xylanase was inhibited by the presence of $Ca^{2+}$, $Mn^{2+}$, $Fe^{2+}$, $Cu^{2+}$, $Al^{3+}$ or EDTA, and activated by $K^+$, $Ag^+$ or DTT. This xylanase was stable at $40^{\circ}C$ for 120 min, but lost almost their activity in 30 min at $60^{\circ}C$. Zymography analysis of concentrated culture supernatant revealed one major band at 42 kDa and two faint bands at 68 and 120 kDa.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.4
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• pp.351-359
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• 2011

In a structure, damage can occur at several scales from micro-cracking to corrosion or loose bolts. This makes the identification of damage difficult with one mode of sensing. Hence, a multi-mode actuated sensing system is proposed based on a self-sensing circuit using a piezoelectric sensor. In the self sensing-based multi-mode actuated sensing, one mode provides a wide frequency-band structural response from the self-sensed impedance measurement and the other mode provides a specific frequency-induced structural wavelet response from the self-sensed guided wave measurement. In this study, an experimental study on the pipeline system is carried out to verify the effectiveness and the robustness of the proposed structural health monitoring approach. Different types of structural damage are artificially inflicted on the pipeline system. To classify the multiple types of structural damage, a supervised learning-based statistical pattern recognition is implemented by composing a two-dimensional space using the damage indices extracted from the impedance and guided wave features. For more systematic damage classification, several control parameters to determine an optimal decision boundary for the supervised learning-based pattern recognition are optimized. Finally, further research issues will be discussed for real-world implementation of the proposed approach.

• Microbiology and Biotechnology Letters
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• v.37 no.1
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• pp.62-68
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• 2009

The culture conditions to maximize the production of laccase (EC 1.10.3.2) from Fomitopsis pinicola mycelia were investigated. Among the tested media for the enzyme production, mushroom complete medium (MCM ; 2% dextrose, 0.2% peptone, 0.2% yeast extract, 0.05% $KH_2PO_4$, and 0.05% $MgSO_4{\cdot}7H_2O$) showed the highest activity of the enzyme. To optimize the culture condition for the laccase activity, influence of various carbon and nitrogen sources was investigated in MCM. Among various carbon and nitrogen sources, 2% glucose and 0.4% peptone showed the highest production of the enzyme, respectively. For the phosphorus and inorganic source, 0.05% $NaH_2PO_4$ and 0.05% $CaCl_2$ were best for the enzyme activity. The enzyme production was reached to highest level after the cultivation for 8 days at $25^{\circ}C$. Native polyacrylamide gel electrophoresis (PAGE) followed by the laccase activity staining using 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as the substrate was performed to identify the laccase under culture conditions studied. Zymogram analysis of the culture supernatant showed a laccase band with molecular mass of 52 kDa. The optimum pH and temperature for the enzyme activity were $80^{\circ}C$ and pH 3.0.