• Korean Journal of Optics and Photonics
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• v.10 no.3
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• pp.195-200
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• 1999

We made sharp optical fiber tips with less than 100 nm diameter by using the heating and pulling method with a good repetition and fabricated the photon scanning tunneling microscope (PSTM) using constant intensity mode. The 3-dimensional PZT (Piezoelctric transducer) scanner made of a long PZT tube is consisted of three divided parts, that is, a pair of $\pm$ x and a pair of $\pm$y scanning parts and a z scanning part for the fine approach and scanning. The scanning dimension is 1.43 $\mu\textrm{m}$$\times$1.76 $\mu\textrm{m}$. The height of a optical tip to maintain a constant height within $1/{\lambda}_0$ (${\lambda}_0$ is the incident wavelength) from surface of a specimen to a optical tip is controlled automatically by using the electric feedback circuit. The 3-dimensional shape of standing evanescent waves generated on the surface of a dove prism was measured successfully by using the constant intensity mode PSTM.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.10
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• pp.1371-1377
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• 2012

Biological activities of Korean Panax ginseng 55% ethanol extract (KPGE) were investigated. The measured total polyphenol content of KPGE was 357.45 mg/100 g. KPGE showed the highest ${\alpha},{\alpha}$-diphenyl-${\beta}$-picrylhydrazyl (DPPH) and 2,2'-azino-bis-3-ethylbenzo-thiazoline-6-sulfonic acid (ABTS) radical scavenging activities of 80% and 86% at 1,000 ${\mu}g/mL$, respectively. DPPH and ABTS radical scavenging activities significantly increased in a KPGE concentration-dependent manner. SOD-like activity of KPGE (1, 10, and 100 ${\mu}g/mL$) increased from 22% up to 33% at KPGE concentrations of 500 and 1,000 ${\mu}g/mL$. KPGE treatment significantly suppressed the generation of pro-inflammatory mediators, including nitric oxide (NO), prostaglandin $E_2$ ($PGE_2$), and cytokines (tumor necrosis factor-alpha: TNF-${\alpha}$, interleukin-6: IL-6, interleukin-$1{\beta}$: IL-$1{\beta}$), in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. KPGE demonstrated strong anti-inflammatory activity that reduced NO and $PGE_2$ production in LPS-stimulated RAW 264.7 cells. Even low concentrations of KPGE (1 and 10 ${\mu}g/mL$) reduced $PGE_2$ and NO production in RAW 264.7 macrophages without LPS-stimulation, respectively. At concentrations of 100, 500, and 1,000 ${\mu}g/mL$, TNF-${\alpha}$, IL-$1{\beta}$ and IL-6 production were significantly suppressed. The results of our study suggest the potential of Korean Panax ginseng as an excellent antioxidant substance for inhibiting inflammatory mediators. Therefore, Korean Panax ginseng (KPGE) may be used as a therapeutic approach to various inflammatory diseases.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.743-748
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• 2012

This study presents the effects of micro-geometries on the swimming behavior of Pseudomonas aeruginosa. First, we have measured parameters of single-cell motility including cell speed, run duration time, and tumble angle under two dimensional space. The results are used to calculate motility coefficients in the width of microchannels ranging from 10 to $100{\mu}m$. Since the single-cell motility parameters measured depend on the interaction of flagella with the microchannel wall, the duration time of the running cell in restricted geometries is distinctively different. Therefore, the motility of bacteria is decreased by restricted geometries. This study suggests that microfluidic approach is useful tool for the analysis of bacterial motility under the restricted space and rapid analytical tool.

• Korean Journal of Environmental Agriculture
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• v.37 no.2
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• pp.125-134
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• 2018

BACKGROUND: Green peach aphid (Myzus persicae) is an insect pest that significantly affects crop production. A number of pesticides have been used for aphid control, but their concerns on insect resistance and food safety have required alternative methods for pest management. In an effort to find for an alternative approach to aphid control, we screened plants extracts and examined their potentiality as insecticidal bio-resources. METHODS AND RESULTS: Two hundred and ninety eight plant extracts were examined for insecticidal activity against the aphid, and the best candidate among them was chosen for further study. The extracts from Cinnamomum camphora was determined to be the best candidate exhibiting insecticidal activity more than 60% at a level of $1,000{\mu}g/mL$. GC/MS analyses detected camphor, borneol, 4-terpineol, ${\alpha}$-terpineol and caryophyllene oxide as major compositions from the extracts obtained by hydrodistillation. Caryophyllene oxide exhibited the highest insecticidal activity with a $LC_{50}$ value of $237{\mu}g/mL$. Camphor lowered significantly the $LC_{50}$ value of caryophyllene oxide and increased largely its concentration in aphid, suggesting that camphor played a role in enhancing the insecticidal activity of caryophyllene oxide. CONCLUSION: This study suggested that camphor and caryophyllene oxide may be used as an insecticidal bio-resource for insect control against green peach aphid.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.1
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• pp.131-139
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• 1987

In this study, characteristics of multi-photos and optimal photographing method are suggested by analyzing the normal case and convergent case with multiple method. The optimal photographing method is applied to deformation measurement of a model miniature structure under loading. Comparing with conventional measurement method in accuracy, efficiency and proprities of application of this method are suggested. As a result, the optimal photographing condition is ideal at $90^{\circ}$ convergent multiple case, whose measurement values approach to that of precision level within $5{\sim}9{\mu}m$ and bring more than about 55% improvement of accuracy comparing with normal case at the number of photos respectively. Therefore application of this method in deformation measurement as well as precision analysis of structures is desired in precision and economical aspect.

• Explosives and Blasting
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• v.23 no.3
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• pp.27-42
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• 2005

An explosion modeling technique was developed by using the spherical discrete element code, $PFC^{3D}$, which can be used to model the dynamic stress wave propagation phenomenon. The modeling technique is simply based on an idea that the explosion pressure should be applied to a $PFC^{3D}$ particle assembly not in the form of an external force (body force), but in the form of a contact force (surface force). The stress wave propagation modeling was conducted by simulating the experimental approach based on the Hopkinson's effect combined with the spatting phenomenon that had previously been developed to determine the dynamic tensile strength of Inada granite. As a result, the stress wave velocity obtained by the proposed modeling technique was 4167 m/s, which is merely $3\%$ lower than the actual wave velocity of 4300 m/s for an Inada granite.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.409-413
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• 2005

A method to estimate the autotrophic maximum specific growth rate is presented in this paper. First of all, the concentration of nitrifier is simulated based on the amount of N nitrified, the sludge age and the default value for the decay coefficient. Secondly the OUR of the sludge with access of ammonia is measured. The maximum specific growth rate can be calculated as ${\mu}_{max,A}\;=\;OUR_{max,A}/Y_A$. It was demonstrated that the maximum specific growth rate of autotrophic biomass is not a constants but a time variable parameter. It is concluded that using $OUR_{max,A}$ for dynamic estimating maximum specific growth rate is a good approach and that using a constant value for the maximum specific growth rate over a longer period of time could not predict the performance of activated sludge plants.

• Journal of Microbiology and Biotechnology
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• v.28 no.4
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• pp.638-644
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• 2018

In this study, the immobilization of xylanase using a protein-inorganic hybrid nanoflower system was assessed to improve the enzyme properties. The synthesis of hybrid xylanase nanoflowers was very effective at $4^{\circ}C$ for 72 h, using 0.25 mg/ml protein, and efficient immobilization of xylanase was observed, with a maximum encapsulation yield and relative activity of 78.5% and 148%, respectively. Immobilized xylanase showed high residual activity at broad pH and temperature ranges. Using birchwood xylan as a substrate, the $V_{max}$ and $K_m$ values of xylanase nanoflowers were 1.60 mg/ml and $455{\mu}mol/min/mg$ protein, compared with 1.42 mg/ml and $300{\mu}mol/min/mg$ protein, respectively, for the free enzyme. After 5 and 10 cycles of reuse, the xylanase nanoflowers retained 87.5% and 75.8% residual activity, respectively. These results demonstrate that xylanase immobilization using a proteininorganic hybrid nanoflower system is an effective approach for its potential biotechnological applications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.11
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• pp.2037-2042
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• 2017

The manufacturing facility is generally operated by a pre-set program under the existing factory automation system. On the other hand, the manufacturing facility must decide how to operate autonomously in Industry 4.0. Determining the operation mode of the production facility itself means, for example, that it detects the abnormality such as the deterioration of the facility at the shop-floor, prediction of the occurrence of the problem, detection of the defect of the product, In this paper, we propose a manufacturing process modeling using a queue for detection of manufacturing process abnormalities at the shop-floor, and detect abnormalities in the modeling using SVM, one of the machine learning techniques. The queue was used for M / D / 1 and the conveyor belt manufacturing system was modeled based on ${\mu}$, ${\lambda}$, and ${\rho}$. SVM was used to detect anomalous signs through changes in ${\rho}$.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.10a
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• pp.25-25
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• 2018

The Fukushima Daiichi Nuclear Power Plant accident in March 2011 caused severe radioactive contamination in the surrounding environment. Since the accident, much attention has been paid to the biological and genetic consequences of organism inhabiting the contaminated area. The effect of radiation exposure on genetic mutation rates is little known, especially for low doses and in situ conditions. Evaluating DNA mutation by low levels of radiation dose is difficult due to the rare mutation event and lack of sequence information before the accident. In this study, correlations with air dose levels and somatic DNA mutation rates were evaluated using Next Generation Sequencer for the clonal plant, Phyllostachys edulis. This bamboo is known to spread an identical clone throughout Japan, and it has the advantage that we can compare genetic mutation rate among identical clone growing different air dose levels. We collected 94 samples of P. edulis from 14 sites with air dose rates from $0.04{\sim}7.80{\mu}Gy/h$. Their clonal identity was confirmed by analysis using 24 microsatellite markers, and then, sequences among samples were compared by MIG sequence. The sequence data were obtained from 2,718 loci. About ~200,000 bp sequence (80 bp X 2,718 loci) were obtained for each sample, and this corresponds to about 0.01% of the genome sequence of P. edulis. In these sequences, 442 loci showed polymorphism patterns including recent origin mutation, old mutation, and sequence errors. The number of mutations per sample ranged from 0 to 13, and did not correlate with air dose levels. This result indicated that DNA mutations have not accumulated in P. edulis living in the air doses levels less than $10{\mu}Gy/h$. Our study also suggests that mutation rates can be assessed by selecting an appropriate experimental approach and analyzing with next generation sequencer.