• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.10
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• pp.1331-1335
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• 2009

We have studied the anti-diabetic effects of medicinal plant water extracts on hepatic glucose-regulating enzymes such as glucokinase (GK) and acetyl-CoA carboxylase (ACC). $\alpha$-Glucosidase inhibitor is usually used to prevent and treat type II diabetes; thus, anti-$\alpha$-glucosidase activity of medicinal plant water extracts was assayed. The hepatic cytosol faction of a type II diabetic animal (Goto-Kakizaki rat) was used in GK and ACC activity assays. The medicinal plants were Lycium chinense (JGP), Discorea japonica Thunb. (SY), Pyrus pyrifolia (YSB), Cornus officinalis (SSY), Paeonia suffruticosa ANDR. (MDP), Cordyceps militaris (DCH), and Acanthopanax senticosus (GSO). JGP, SY, YSB, and SSY water extracts increased the hepatic GK activity and all medicinal plant water extracts led to an increase in hepatic ACC activity. YSB, SSY, MDP, and GSO water extracts showed significantly higher anti-$\alpha$-glucosidase activity than control samples. The highest anti-$\alpha$-glucosidase activity was observed in GSO water extract and the anti-$\alpha$-glucoside activity was higher than that of Acarbose (reference $\alpha$-glucosidase inhibitor). We suggest that JGP, SY, YSB, and SSY water extracts may exert an anti-diabetic effect by enhancing the glucose metabolism and that YSB, MDP and GSO may be used as natural $\alpha$-glucosidase inhibitors in type II diabetic conditions. Increased ACC activity by plant water extracts may provide additional anti-diabetic effect.

• Journal of Microbiology and Biotechnology
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• v.13 no.4
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• pp.628-631
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• 2003

The recombinant alanine dehydrogenase (ADH) from E. coli containing Thermus caldophilus ADH was purified to homogeneity from a cell-free extract. The enzyme was purified 38-fold with a yield of 68% from the starting cell-free extract. The purified enzyme gave a single band in polyacrylamide gel electrophoresis, and its molecular weight was estimated to be 45 kDa. The pH optimum was 8.0 for reductive amination of pyruvate and 12.0 for oxidative deamination of L-alanine. The enzyme was stable up to $70^{\circ}C$. The activity of the enzyme was inhibited by 1 mM $Zn^{2+}$, 20% hexane, and 20% $CHCl_3$. However, 10 mM $Mg^{2+}$ and 40% propanol had no effect on the enzyme activity. The Michaelis constants ($K_m$) for the substrates were $50\;\mu\textrm{M}$ for NADH, 0.2 mM for pyruvate, 39.4 mM for $NH_4+$, 2.6 mM for L-alanine, and 1.8 mM for $NAD^+$.

• Management & Information Systems Review
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• v.30 no.2
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• pp.237-255
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• 2011

This empirical study is focused on practical application of Range-Based Volatility which is estimated by opening, high, low, closing price of overall asset. Especially proper forecasting period is what I want to know. There is four useful Range-Based Volatility(RV) such as Parkinson(1980; PK), Garman and Klass(1980; GK) Rogers and Satchell(1991; RS), Yang and Zhang(2008; YZ). So, four RV of KOPSI 200 index during 2000.5.22-2009.9.18 was used for empirical test. The emprirical result as follows. First, the best RV which shows the best forecasting performance is PK volatility among PK, GK, RS, YZ volatility. According to estimating period forcasting performance of RV shows delicate difference. PK has better performance in the period with financial crisis of sub-prime mortgage loan. if not, RS is better. Second, almost result shows better performance on forecasting volatility without sub-prime mortgage loan period. so we can say that forecasting performance is lower when historical volatiltiy is comparatively high. Finally, I find that longer estimating period in AR(1) and MA(1) model can reduce forecasting error. More interesting point is that the result shows rapid decrease form 60 days to 90 days and there is no more after 90 days. So, if we forecast the volatility using Range-Based volaility it is better to estimate with 90 trading period or over 90 days.

• Journal of Astronomy and Space Sciences
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• v.35 no.4
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• pp.227-233
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• 2018

This study presents the generation and accuracy assessment of predicted orbital ephemeris based on satellite laser ranging (SLR) for geostationary Earth orbit (GEO) satellites. Two GEO satellites are considered: GEO-Korea Multi-Purpose Satellite (KOMPSAT)-2B (GK-2B) for simulational validation and Compass-G1 for real-world quality assessment. SLR-based orbit determination (OD) is proactively performed to generate orbital ephemeris. The length and the gap of the predicted orbital ephemeris were set by considering the consolidated prediction format (CPF). The resultant predicted ephemeris of GK-2B is directly compared with a pre-specified true orbit to show 17.461 m and 23.978 m, in 3D root-mean-square (RMS) position error and maximum position error for one day, respectively. The predicted ephemeris of Compass-G1 is overlapped with the Global Navigation Satellite System (GNSS) final orbit from the GeoForschungsZentrum (GFZ) analysis center (AC) to yield 36.760 m in 3D RMS position differences. It is also compared with the CPF orbit from the International Laser Ranging Service (ILRS) to present 109.888 m in 3D RMS position differences. These results imply that SLR-based orbital ephemeris can be an alternative candidate for improving the accuracy of commonly used radar-based orbital ephemeris for GEO satellites.

• Mycobiology
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• v.29 no.4
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• pp.218-223
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• 2001

A rapid radicle assay for prescreening antagonistic bacteria to Phytophthora capsic4 causal agent of Phytophthora blight of pepper was developed. Sixty-four bacterial strains with in vitro antifungal activity selected out of 1,400 strains isolated from soils of Ansung, Chunan, Koyang, and Paju, Korea in 1998 were used for development of the bioassay. Uniformly germinated pepper seeds dipped in bacterial cells for 3 hours were placed near the edges of growing mycelia of P. capsici on water agar containing 0.02% glucose. Five-week-old pepper plants(cv. Nockwang) were inoculated to compare with results of the radicle assay developed in this study. For plant inoculation, pepper seeds were sown in potting mixtures incorporated with the bacterial strains, then transplanted into steam-sterilized soils 3 weeks later. Plants were hole-inoculated with zoospores of P. capsici 2 weeks after transplanting. Disease incidence and severity were determined in radicle and plant assessments, respectively. In radicle assay, six strains, GK-B15, GK-B25, OA-B26, OA-B36, PK-B09, and VK-B14 consistently showed the significant(P=0.05) disease reduction against radicle infection by the fungus, four of which also did in plant assessments. Strains OA-B36 and GK-B15 consistently reduced the fungal infection in both the radicle assay and the plant assessment. Therefore, prescreening strains using the radicle assay developed in this study followed by plant assay could reduce time and labor, and improved the possibility of selecting antagonistic bacteria for control of Phytophthora blight of peppers.

• Korean Journal of Remote Sensing
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• v.37 no.6_1
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• pp.1631-1645
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• 2021

This research aims to provide the characteristics of the world's first active lidar sensor Atmospheric Laser Doppler Instrument (ALADIN) wind data and Geostationary Korea Multi Purpose Satellite 2A (GK2A) Atmospheric Motion Vector (AMV) data by comparing two wind data. As a result of comparing the data from September 2019 to August 1, 2020, The total number of collocated data for the AMV (using IR channel) and Mie channel ALADIN data is 177,681 which gives the Root Mean Square Error (RMSE) of 3.73 m/s and the correlation coefficient is 0.98. For a more detailed analysis, Comparison result considering altitude and latitude, the Normalized Root Mean Squared Error (NRMSE) is 0.2-0.3 at most latitude bands. However, the upper and middle layers in the lower latitudes and the lower layer in the southern hemispheric are larger than 0.4 at specific latitudes. These results are the same for the water vapor channel and the visible channel regardless of the season, and the channel-specific and seasonal characteristics do not appear prominently. Furthermore, as a result of analyzing the distribution of clouds in the latitude band with a large difference between the two wind data, Cirrus or cumulus clouds, which can lower the accuracy of height assignment of AMV, are distributed more than at other latitude bands. Accordingly, it is suggested that ALADIN wind data in the southern hemisphere and low latitude band, where the error of the AMV is large, can have a positive effect on the numerical forecast model.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.1
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• pp.28-36
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• 2023

Solar radiation that is measured at relatively small number of weather stations is one of key inputs to crop models for estimation of crop productivity. Solar radiation products derived from GK-2A and Himawari 8 satellite data have become available, which would allow for preparation of input data to crop models, especially for assessment of crop productivity under an agrivoltaic system where crop and power can be produced at the same time. The objective of this study was to compare the degree of agreement between the solar radiation products obtained from those satellite data. The sub hourly products for solar radiation were collected to prepare their daily summary for the period from May to October in 2020 during which both satellite products for solar radiation were available. Root mean square error (RMSE) and its normalized error (NRMSE) were determined for daily sum of solar radiation. The cumulative values of solar radiation for the study period were also compared to represent the impact of the errors for those products on crop growth simulations. It was found that the data product from the Himawari 8 satellite tended to have smaller values of RMSE and NRMSE than that from the GK-2A satellite. The Himawari 8 satellite product had smaller errors at a large number of weather stations when the cumulative solar radiation was compared with the measurements. This suggests that the use of Himawari 8 satellite products would cause less uncertainty than that of GK2-A products for estimation of crop yield. This merits further studies to apply the Himawari 8 satellites to estimation of solar power generation as well as crop yield under an agrivoltaic system.

• Journal of Korea Water Resources Association
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• v.55 no.12
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• pp.1125-1135
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• 2022

Damages by heavy snow does not occur very often, but when it does, it causes damage to a wide area. To mitigate snow damage, it is necessary to know, in advance, the depth of snow that causes damage in each region. However, snow depths are measured at observatory locations, and it is difficult to understand the spatial distribution of snow depth that causes damage in a region. To understand the spatial distribution of snow depth, the point measurements are interpolated. However, estimating spatial distribution of snow depth is not easy when the number of measured snow depth is small and topographical characteristics such as altitude are not similar. To overcome this limit, satellite images such as Synthetic Aperture Radar (SAR) can be analyzed using Differential Interferometric SAR (DInSAR) method. DInSAR uses two different SAR images measured at two different times, and is generally used to track minor changes in topography. In this study, the spatial distribution of snow depth was estimated by DInSAR analysis using dual polarimetric IW mode C-band SAR data of Sentinel-1B satellite operated by the European Space Agency (ESA). In addition, snow depth was estimated using geostationary satellite Chollian-2 (GK-2A) to compare with the snow depth from DInSAR method. As a result, the accuracy of snow cover estimation in terms with grids was about 0.92% for DInSAR and about 0.71% for GK-2A, indicating high applicability of DInSAR method. Although there were cases of overestimation of the snow depth, sufficient information was provided for estimating the spatial distribution of the snow depth. And this will be helpful in understanding regional damage-causing snow depth.

• Toxicological Research
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• v.28 no.1
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• pp.19-24
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• 2012

In the present study, toxicity of silver nanoparticles (AgNPs) was investigated in the nematode, Caenohabditis elegans focusing on the upstream signaling pathway responsible for regulating oxidative stress, such as mitogen-activated protein kinase (MAPK) cascades. Formation of reactive oxygen species (ROS) was observed in AgNPs exposed C.elegans, suggesting oxidative stress as an important mechanism in the toxicity of AgNPs towards C. elegans. Expression of genes in MAPK signaling pathways increased by AgNPs exposure in less than 2-fold compared to the control in wildtype C.elegans, however, those were increased dramatically in sod-3 (gk235) mutant after 48 h exposure of AgNPs (i.e. 4-fold for jnk-1 and mpk-2; 6-fold for nsy-1, sek-1, and pmk-1, and 10-fold for jkk-1). These results on the expression of oxidative stress response genes suggest that sod-3 gene expression appears to be dependent on p38 MAPK activation. The high expressions of the pmk-1 gene 48 h exposure to AgNPs in the sod-3 (gk235) mutant can also be interpreted as compensatory mechanisms in the absence of important stress response genes. Overall results suggest that MAPK-based integrated stress signaling network seems to be involved in defense to AgNPs exposure in C.elegans.

• Korean Journal of Remote Sensing
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• v.37 no.5_2
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• pp.1235-1243
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• 2021

Geostationary Ocean Color Imager 2 (GOCI-II) on Geo-KOMPSAT-2 (GK2B)satellite was developed as a mission successor of GOCI on COMS which had been operated for around 10 years since launch in 2010 to observe and monitor ocean color around Korean peninsula. GOCI-II on GK2B was successfully launched in February of 2020 to continue for detection, monitoring, quantification, and prediction of short/long term changes of coastal ocean environment for marine science research and application purpose. GOCI-II had already finished IAC and IOT including early in-orbit calibration and had been handed over to NOSC (National Ocean Satellite Center) in KHOA (Korea Hydrographic and Oceanographic Agency). Radiometric calibration was periodically conducted using on-board solar calibration system in GOCI-II. The final calibrated gain and offset were applied and validated during IOT. And three video parameter sets for one day and 12 video parameter sets for a year was selected and transferred to NOSC for normal operation. Star measurement-based INR (Image Navigation and Registration) navigation filtering and landmark measurement-based image geometric correction were applied to meet the all INR requirements. The GOCI2 INR software was validated through INR IOT. In this paper, status and results of IOT, radiometric calibration and INR of GOCI-II are analysed and described.