• Korean Journal of Remote Sensing
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• v.33 no.6_1
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• pp.1029-1040
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• 2017

Wildfires release a large amount of greenhouse gases (GHGs) into the atmosphere. Fire radiative power (FRP) data obtained from geostationary satellites can play an important role for tracing the GHGs. This paper describes an estimation of the Himawari-8 FRP and fire emissions for Samcheock and Gangnueng wildfire in 6 May 2017. The FRP estimated using Himawari-8 well represented the temporal variability of the fire intensity, which cannot be captured by MODIS (Moderate Resolution Imaging Spectroradiometer) because of its limited temporal resolution. Fire emissions calculated from the Himwari-8 FRP showed a very similar time-series pattern compared with the AirKorea observations, but 1 to 3 hour's time-lag existed because of the distance between the station and the wildfire location. The estimated emissions were also compared with those of a previous study which analyzed fire damages using high-resolution images. They almost coincided with 12% difference for Samcheock and 2% difference for Gangneung, demonstrating a reliability of the estimation of fire emissions using our Himawari-8 FRP without high-resolution images. This study can be a reference for estimating fire emissions using the current and forthcoming geostationary satellites in East Asia and can contribute to improving accuracy of meteorological products such as AOD (aerosol optical depth).

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.4
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• pp.261-265
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• 2003

Cold air accumulation plays a critical role in formulating daily minimum temperature in complex terrain on radiative cooling nights, and spatial interpolation can be improved by accommodating this important topoclimatic variable. Little is known about the spatial scale for computing cold air accumulation which influences daily minimum temperature. Air temperature was measured at 10-minute intervals during September 2002- February 2003 at eight locations within a 1 by 1 km hilly orchard area. Minimum temperature data for suspected radiative cooling nights were collected, and the deviations from reference observations at a near-by KMA automated weather station were calculated. A digital elevation model with a 10m cell size was used to calculate the cold air accumulation at 8 locations. Zonal averages of the cold air accumulation were computed for each location by increasing the cell radius from 1 to 10. Temperature deviations were regressed to a common logarithm of the smoothed averages of cold air accumulation to derive a linear relationship between the local temperature deviation and the site topography. The highest coefficient of determination ($r^2$ = 0.78) was found at a cell radius of 5, which corresponds to an approximately 1 ha boundary surrounding the point of interest.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.1
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• pp.61-68
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• 2010

In this work, a reduced size 20W quasi class-E Power Amplifier(PA) with defected ground structure load-network is presented for WCDMA base station application. Harmonic impedances required for the class E operation are satisfied by applying the dumbbell and the asymmetric spiral DGS. Open impedance for 2nd harmonic frequency which has the highest power and nearly short impedances for other higher order harmonics are provided by the proposed DGS load-network. The maximum Power Added Efficiency(PAE) of 70.2 % at the output power of 43.1 dBm with the saturated power gain of 12.7 dB is achieved by the proposed quasi class-E PA, which is comparable to the performance of the reference class-E PA. Total size of the proposed class-E PA is only $50{\times}50\;mm^2$ and much smaller than the conventional class-E PA that is loaded with a number of open stubs.

• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.1
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• pp.40-49
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• 2013

Current service system of the Korea Meteorological Administration (KMA) for blooming date forecasting in spring depends on regression equations derived from long term observations in both temperature and phenology at a given station. This regression based system does not allow a timely correction or update of forecasts that are highly sensitive to fluctuating weather conditions. Furthermore, the system cannot afford plant responses to climate extremes which were not observed before. Most of all, this method may not be applicable to locations other than that which the regression equations were derived from. This note suggests a way to replace the location restricted regression equations with a thermal time based phenology model to complement the KMA blooming forecast system. Necessary parameters such as reference temperature, chilling requirement and heating requirement were derived from phenology data for forsythia, azaleas and Japanese cherry at 29 KMA stations for the 1951-1980 period to optimize spring phenology prediction model for each species. Best fit models for each species were used to predict blooming dates and the results were compared with the observed dates to produce a correction grid across the whole nation. The models were driven by the KMA's daily temperature data at a 5km grid spacing and subsequently adjusted by the correction grid to produce the blooming date maps. Validation with the 1971-2012 period data showed the RMSE of 2-3 days for Japanese cherry, showing a feasibility of operational service; whereas higher RMSE values were observed with forsythia and azaleas.

• Ocean and Polar Research
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• v.39 no.1
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• pp.13-21
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• 2017

Temporal changes in the number of zooplankton species are important information for understanding basic characteristics and species diversity in marine ecosystems. The aim of the present study was to estimate the optimal monitoring frequency (OMF) to guarantee and predict the minimum number of species occurrences for studies concerning marine ecosystems. The OMF is estimated using the temporal number of zooplankton species through bi-weekly monitoring of zooplankton species data according to operational taxonomic units in the Tongyoung coastal sea. The optimal model comprises two terms, a constant (optimal mean) and a cosine function with a one-year period. The confidence interval (CI) range of the model with monitoring frequency was estimated using a bootstrap method. The CI range was used as a reference to estimate the optimal monitoring frequency. In general, the minimum monitoring frequency (numbers per year) directly depends on the target (acceptable) estimation error. When the acceptable error (range of the CI) increases, the monitoring frequency decreases because the large acceptable error signals a rough estimation. If the acceptable error (unit: number value) of the number of the zooplankton species is set to 3, the minimum monitoring frequency (times per year) is 24. The residual distribution of the model followed a normal distribution. This model can be applied for the estimation of the minimal monitoring frequency that satisfies the target error bounds, as this model provides an estimation of the error of the zooplankton species numbers with monitoring frequencies.

• Journal of Astronomy and Space Sciences
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• v.27 no.2
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• pp.89-96
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• 2010

BVR CCD observations of GW Cep were made on 15 nights in November through December 2008 with a 1-m reflector at the Jincheon station of the Chungbuk National University Observatory. Nineteen new times of minimum lights for GW Cep were determined and added to a collection of all other times of minima available to us. These data were then intensively analyzed, by reference to an O-C diagram, to deduce the general form of period variation for GW Cep. It was found that the O-C diagram could be interpreted as presenting two different forms of period change: an exclusively quasi-sinusoidal change with a period of 32.6 years and an eccentricity of 0.10; and a quasi-sinusoidal change with a period of 46.2 years and an eccentricity of 0.36 superposed on an upward parabola. Although a final conclusion is somewhat premature at present, the latter seems more plausible because late-type contact binaries allow an inter-exchange of both energy and mass between the component stars. The quasi-sinusoidal characteristics were interpreted in terms of a light-time effect due to an unseen tertiary component. The minimum masses of the tertiary component for both cases were calculated to be nearly the same as the $0.23-0.26M\;{\odot}$-ranges which is hardly detectable in a light curve synthesis. The upward parabolic O-C diagram corresponding to a secular period increase of about $4.12{\times}10^{-8}\;d/yr$ was interpreted as mass being transferred from the lesser to more massive component. The transfer rate for a conservative case was calculated to be about $2.66\;{\times}\;10^{-8}\;M_{\odot}/yr$ which is compatible with other W UMa-type contact binaries.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.648-654
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• 2016

This paper investigates differences of tourism destination choices for sightseeing in Seoul between first-time visitors and repeat visitors. We constructed social network using secondary data from '2015 International Visitor Survey' and analyzed its density and centrality. Study results find that: (1) first-time and repeat visitors' tourism destinations are concentrated in areas located north of the Han river. The proximity of destinations suggests the positive effects resulting from the movement network. (2) As the result of degree centrality, closeness centrality, betweenness centrality, the highest ranking tourism destinations for both visitor groups are identical, but indexes of centralities in repeat visitors' destinations increase, including Shinchon/ Hongik University, Gangnam station, and Garosu-gil. Therefore, the roles of these destinations are becoming established as tourism hubs and are popular among younger visitors as well as attract repeat visitors. Results of this study will be a useful reference in developing and managing new tourism products.

• Korean Journal of Medicinal Crop Science
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• v.2 no.2
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• pp.154-161
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• 1994

This experiment was carried out to establish micropropagation system in Fritillaria thunbergii Miq. Through the culture of bulblet scales, stems, node-buds and shoot tips with special reference to the effect of physiological age of explant and plant growth regulators on bulblet formation. Number of formed bulblets was significantly increased in node-bud or stem tissue compared to scals segments and on the medium supplemented with kinetin than BA containing medium. Optimum levels of kinetin for bulblet formation from node-bud taken from above 3 cm shoot length and stem segments excised from below 3 cm shoot length were 5.0 mg /L and $1.0{\sim}3.0\;mg$ /L kinetin, respectively. Interesting phenomenon was observed, the direct formation of bulblets from the axilliary bud of cultured explants. Bulblet forming capacity in stem tissue was depended on stem age, young stem had high regeneration ability compared to old stem taken from above 10 cm shoot length. 1.0 mg /L kinetin was optimum concentration for the formation of bulblets from old stem segments. Stem tissue taken from underground growing plant was promoted coampare to shoot tips or bulb scale segments. Optimum concentration of sucrose was $5{\sim}7%$. Summariged above results revealed that effective explant for micropropagation was stem and /or node-bud tissue excised from less than 3 cm plant height compared to those of bulb scale segments which showed high contamination after culture. Maximum multiplication rate of young stem and /or node-bud segment was about 20 times. Kinetin requirement for stimulation of bulblet formation from cultured explant depended on source of explants but favorable levels of kinetin for organogenesis ranged from 1.0 mg /L to 5.0 mg /L.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.4
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• pp.43-48
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• 2015

We studied on pseudo-range correction(PRC) modeling in order to improve differential GNSS(DGNSS) accuracy. The PRC is the range correction information that provides improved location accuracy using DGNSS technique. The digital correction signal is typically broadcast over ground-based transmitters. Sometimes the degradation of the positioning accuracy caused by the loss of PRC signals, radio interference, etc. To prevent the degradation, in this paper, we have designed a PRC model through polynomial curve fitting and evaluated this model. We compared two quantities, estimations of PRC using model parameters and observations from the reference station. In the case of GPS, the average is 0.1m and RMSE is 1.3m. Most of GPS satellites have a bias error of less than ${\pm}1.0m$ and a RMSE within 3.0m. In the case of GLONASS, the average and the RMSE are 0.2m and 2.6m, respectively. Most of satellites have less than ${\pm}2.0m$ for a bias error and less than 3.0m for RMSE. These results show that the estimated value calculated by the model can be used effectively to maintain the accuracy of the user's location. However;it is needed for further work relating to the big difference between the two values at low elevation.

• Molecules and Cells
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• v.38 no.5
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• pp.466-473
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• 2015

Over the last 30 years, Hanwoo has been selectively bred to improve economically important traits. Hanwoo is currently the representative Korean native beef cattle breed, and it is believed that it shared an ancestor with a Chinese breed, Yanbian cattle, until the last century. However, these two breeds have experienced different selection pressures during recent decades. Here, we whole-genome sequenced 10 animals each of Hanwoo and Yanbian cattle (20 total) using the Illumina HiSeq 2000 sequencer. A total of approximately 3.12 and 3.07 billion sequence reads were mapped to the bovine reference sequence assembly (UMD 3.1) at an average of approximately 10.71- and 10.53-fold coverage for Hanwoo and Yanbian cattle, respectively. A total of 17,936,399 single nucleotide polymorphisms (SNPs) were yielded, of which 22.3% were found to be novel. By annotating the SNPs, we further retrieved numerous nonsynonymous SNPs that may be associated with traits of interest in cattle. Furthermore, we performed whole-genome screening to detect signatures of selection throughout the genome. We located several promising selective sweeps that are potentially responsible for economically important traits in cattle; the PPP1R12A gene is an example of a gene that potentially affects intramuscular fat content. These discoveries provide valuable genomic information regarding potential genomic markers that could predict traits of interest for breeding programs of these cattle breeds.