• Journal of Biomedical Engineering Research
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• v.20 no.6
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• pp.515-521
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• 1999

Scintillator crystal is an important part and detcrmines performance characteristics of the gamma camera. We investigated the offects of scintillation crystal surface treatment on gamma camera imaging. Nal(TI) and Csl(Tl) scintillators. 20 mm diameter and 10 mm thickness, applied with two different surface treatments, white and black reflcetors, were applied to Nal(Tl) and Csl(Ti). The optical properties of generated scintillation light were evaluated by Monte Carlo simulation method and by actual measurement using a position sensitive photomultiplier tube (PSPMT). We measured sensitivity, energy resolution and spatial resolution of gamma camera with the various scintillators coupled to a PSPMT. In the simulation. Nal(Tl)-white prosented the best sensitivity. In the measurements, the sensitivities and the intrinsic spatial resolutions of Nal(Tl)-white, Nal(Tl)-black. CsI(Tl)-white, CsI(Tl)-black were 2920, 2322, 1754, 1401 cps/$\mu$ci and 5.2, 4.5, 7.0, 6.3 mm FWHM. respectively. Their intrinsic energy resolutions were mesured 12.5, 23.5, 20.5, 33.3% FWHM at 140 keV Tc-99m. In this study, we investigated the offects of a side surface treatment of the scintillator on the gamma camera imaging. Simulation and measurement prescnted similat trends. Based on the results, we concluded that the surface of th NaI(Tl)seintillator must be treated by absorptive materials in order to develop the gamma camera having good spatial resolution.

• Tunnel and Underground Space
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• v.30 no.4
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• pp.382-393
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• 2020

The engineered barrier system of high-level radioactive waste disposal must maintain its performance in the long term, because it must play a role in slowing the rate of leakage to the surrounding rock mass even if a radionuclide leak occurs from the canister. In particular, it is very important to clarify gas dilation flow phenomenon clearly, that occurs only in a medium containing a large amount of clay material such as a bentonite buffer, which can affect the long-term performance of the bentonite buffer. Accordingly, DECOVALEX-2019 Task A was conducted to identify the hydraulic-mechanical mechanism for the dilation flow, and to develop and verify a new numerical analysis technique for quantitative evaluation of gas migration phenomena. In this study, based on the conventional two-phase flow and mechanical behavior with effective stresses in the porous medium, the hydraulic-mechanical model was developed considering the concept of damage to simulate the formation of micro-cracks and expansion of the medium and the corresponding change in the hydraulic properties. Model verification and validation were conducted through comparison with the results of 1D and 3D gas injection tests. As a result of the numerical analysis, it was possible to model the sudden increase in pore water pressure, stress, gas inflow and outflow rate due to the dilation flow induced by gas pressure, however, the influence of the hydraulic-mechanical interaction was underestimated. Nevertheless, this study can provide a preliminary model for the dilation flow and a basis for developing an advanced model. It is believed that it can be used not only for analyzing data from laboratory and field tests, but also for long-term performance evaluation of the high-level radioactive waste disposal system.

• Journal of Life Science
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• v.27 no.10
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• pp.1152-1160
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• 2017

A unicellular green alga was axenically isolated from a tidal pool on Ulleung-do, Korea. Morphological, molecular, and biochemical analyses revealed that the isolate belonged to Auxenochlorella protothecoides. The current study is the first record of this species in Korea. The microalgal strain was named as A. protothecoides MM0011 and its growth, lipid and pigment compositions, and biomass properties were investigated. The strain is able to thrive in a wide range of temperatures ($5{\sim}35^{\circ}C$) and to withstand up to 1.5 M NaCl. The results of GC/MS analysis showed that the isolate was rich in nutritionally important polyunsaturated fatty acids (PUFAs). Its major fatty acids were linoleic acid (27.6%) and ${\alpha}-linolenic$ acid (39.6%). Thus, this indigenous microalga has potential as an alternative source of ${\omega}3$ and ${\omega}6$ PUFAs, which currently come from fish and plant oils. Also, the HPLC analysis revealed that the value-added antioxidant, lutein, was biosynthesized as the accessory pigments by the microalga. A proximate analysis showed that the volatile matter content was 85.6% and an ultimate analysis indicated that the gross calorific value was $20.3MJ\;kg^{-1}$. Since 40.5% of total nitrogen and 27.9% of total phosphorus were removed from the medium, respectively, it also has potential as a feedstock for biofuel applications which could be coupled to wastewater treatment. In addition, the biomass may also serve as an excellent animal feed because of its high protein content (51.4%). Therefore, A. protothecoides MM0011 shows promise for application in production of microalgae-based biochemicals and as a biomass feedstock.

• Journal of Yeungnam Medical Science
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• v.23 no.1
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• pp.26-35
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• 2006

Background: Luteolin, a flavone found in various Chinese herbal medicines is known to possess anti-inflammatory properties through its ability to inhibit various proinflammatory signaling pathways including NF-${\kappa}B$ and p38 MAPK. In this study, we investigated the potential therapeutic effect of luteolin on dextran sodium sulfate (DSS)-induced colitis. Materials and Methods: We used a transgenic mouse model expressing the enhanced green fluorescent protein (EGFP) under the transcriptional control of NF-${\kappa}B$ $cis$-elements. C57BL/6 NF-${\kappa}B^{EGFP}$ mice received 2.5% DSS in their drinking water for six days in combination with daily luteolin administration (1mg/kg body weight, 0.1ml vol, intragastric) or vehicle. NF-${\kappa}B$ activity was assessed macroscopically with a Charge-Coupled Device (CCD) camera and microscopically by confocal analysis. Results: A significant increase in the Disease Activity Index (DAI), histological score (p<0.05), IL-12 p40 secretion in colonic stripe culture (p<0.05) and EGFP expression was observed in luteolin and/or DSS-treated mice compared to water-treated mice. Interestingly, a trend toward a worse colitis (DAI, IL-12p40) was observed in luteolin-treated mice compared to non-treated DSS-exposed mice. In addition, EGFP expression (NF-${\kappa}B$ activity) strongly increased in the luteolin-treated mice compared to control mice. Confocal microscopy showed that EGFP positive cells were primarily lamina propria immune cells. Conclusions: These results suggest that luteolin is not a therapeutic alternative for intestinal inflammatory disorders derived for primary defects in barrier function. Thus, therapeutic intervention targeting these signaling pathways should be viewed with caution.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.5
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• pp.399-407
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• 2009

Laser induced breakdown spectroscopy(LIBS) is an simple analysis method for directly quantifying many kinds of soil micro-elements on site using a small size of laser without pre-treatment at any property of materials(solid, liquid and gas). The purpose of this study were to find an optimum condition of the LIBS measurement including wavelengths for quantifying soil elements, to relate spectral properties to the concentration of soil elements using LIBS as a simultaneous un-breakdown quantitative analysis technology, which can be applied for the safety assessment of agricultural products and precision agriculture, and to compare the results with a standardized chemical analysis method. Soil samples classified as fine-silty, mixed, thermic Typic Hapludalf(Memphis series) from grassland and uplands in Tennessee, USA were collected, crushed, and prepared for further analysis or LIBS measurement. The samples were measured using LIBS ranged from 200 to 600 nm(0.03 nm interval) with a Nd:YAG laser at 532 nm, with a beam energy of 25 mJ per pulse, a pulse width of 5 ns, and a repetition rate of 10 Hz. The optimum wavelength(${\lambda}nm$) of LIBS for estimating soil and plant elements were 308.2 nm for Al, 428.3 nm for Ca, 247.8 nm for T-C, 438.3 nm for Fe, 766.5 nm for K, 85.2 nm for Mg, 330.2 nm for Na, 213.6 nm for P, 180.7 nm for S, 288.2 nm for Si, and 351.9 nm for Ti, respectively. Coefficients of determination($r^2$) of calibration curve using standard reference soil samples for each element from LIBS measurement were ranged from 0.863 to 0.977. In comparison with ICP-AES(Inductively coupled plasma atomic emission spectroscopy) measurement, measurement error in terms of relative standard error were calculated. Silicon dioxide(SiO2) concentration estimated from two methods showed good agreement with -3.5% of relative standard error. The relative standard errors for the other elements were high. It implies that the prediction accuracy is low which might be caused by matrix effect such as particle size and constituent of soils. It is necessary to enhance the measurement and prediction accuracy of LIBS by improving pretreatment process, standard reference soil samples, and measurement method for a reliable quantification method.

• Journal of the Korean Electrochemical Society
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• v.24 no.4
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• pp.120-132
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• 2021

Although the development of high-Nickel is being actively carried out to solve the capacity limitation and the high price of raw cobalt due to the limitation of high voltage use of the existing LiCoO₂, the deterioration of the battery characteristics due to the decrease in structural stability and increase of the Ni content. It is an important cause of delaying commercialization. Therefore, in order to increase the high stability of the Ni-rich ternary cathod material LiNi_0.6Co_0.2Mn_0.2O₂, precursor Ni_0.6Co_0.2Mn_0.2-x(OH)₂/xTiO₂ was prepared using a nanosized TiO₂ suspension type source for uniform Ti substitution in the precursor. It was mixed with Li₂CO₃, and after heating, the cathode active material LiNi_0.6Co_0.2Mn_0.2-xTi_xO₂ was synthesized, and the physical properties according to the Ti content were compared. Through FE-SEM and EDS mapping analysis, it was confirmed that a positive electrode active material having a uniform particle size was prepared through Ti-substituted spherical precursor and Particle Size Analyzer and internal density and strength were increased, XRD structure analysis and ICP-MS quantitative analysis confirmed that the capacity was effectively maintained even when the Ti-substituted positive electrode active material was manufactured and charging and discharging were continued at high temperature and high voltage.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.2
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• pp.111-120
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• 2022

Improving flour quality is one of the major targets of wheat breeding programs. This study determined the optimum high-molecular-weight glutenin subunits (HMW-GS) to improve flour quality, and analyzed the correlation between agronomic and quality traits in Korea. A total of 180 wheat varieties, including 55 Korean and 125 foreign cultivars, carrying various Glu-1 alleles, were evaluated for their quality and agronomic traits. Results indicated that Glu-A1b, Glu-B1b, and Glu-D1f were the most prevailing alleles for each Glu-1 locus for Korean wheat cultivars. Korean wheat cultivars recorded shorter days to heading (DTH) and longer days to maturity (DTM) compared to foreign cultivars. In addition, an interaction effect was found between Glu-A1 and Glu-B1 alleles on several quality parameters. The combination of Glu-A1c and Glu-B1i showed a higher protein content, dry gluten content, and higher sodium dodecyl sulfate (SDS) sedimentation value than other Glu-A1×Glu-B1 combinations. Cultivars carrying Glu-A1a or Glu-A1b, Glu-B1i or Glu-B1al, and Glu-D1d for each Glu-1 locus exhibited a longer mixing time and stronger mixing tolerance. The DTM positively correlated with the protein content, gluten index and SDS sedimentation value. However, a negative correlation was observed between DTH and quality traits. Owing to the above results, this study suggests that an increase in the frequency of Glu-B1i or Glu-B1al, Glu-D1d coupled with a short DTH and long DTM could significantly improve wheat quality properties.