• Atmosphere
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• v.26 no.1
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• pp.111-126
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• 2016

In the numerical weather model, surface properties can be defined by various parameters such as terrain height, landuse, surface albedo, soil moisture, surface emissivity, roughness length and so on. And these parameters need to be improved in the Seoul metropolitan area that established high-rise and complex buildings by urbanization at a recent time. The surface roughness length map is developed from digital elevation model (DEM) and it is implemented to the high-resolution numerical weather (WISE-WRF) model. Simulated results from WISE-WRF model are analyzed the relationship between meteorological variables to changes in the surface roughness length. Friction speed and wind speed are improved with various surface roughness in urban, these variables affected to temperature and relative humidity and hence the surface roughness length will affect to the precipitation and Planetary Boundary Layer (PBL) height. When surface variables by the WISE-WRF model are validated with Automatic Weather System (AWS) observations, NEW experiment is able to simulate more accurate than ORG experiment in temperature and wind speed. Especially, wind speed is overestimated over $2.5m\;s^{-1}$ on some AWS stations in Seoul and surrounding area but it improved with positive correlation and Root Mean Square Error (RMSE) below $2.5m\;s^{-1}$ in whole area. There are close relationship between surface roughness length and wind speed, and the change of surface variables lead to the change of location and duration of precipitation. As a result, the accuracy of WISE-WRF model is improved with the new surface roughness length retrieved from DEM, and its surface roughness length is important role in the high-resolution WISE-WRF model. By the way, the result in this study need various validation from retrieved the surface roughness length to numerical weather model simulations with observation data.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.1
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• pp.12-19
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• 1999

CERES-rice, a rice growth simulation model, was used in conjunction with daily weather data to figure out the spatial variation of the phenology and yields of paddy rice at 168 rice cultivation zone units(CZU) of Kyunggi Province in 1997. Two sets of cultivar specific coefficients, which represent early and mid-season maturing varieties, were derived from field experiments conducted at two crop experiment stations. The minimum data set to run the model for each CZU (daily maximum and minimum temperature, solar irradiance, and rainfall) was obtained by spatial averaging of existing 'Digital Map of Korean Climate'(Shin et al., 1999). Soil characteristics and management information at each CZU were available from the Rural Development Administration. According to a preliminary test using 5 to 9 years field data, trends of the phasic development(heading and physiological maturity), which were obtained from the model adjusted for these coefficients, were in good agreement with the observed data. However, the simulated inter-annual variation was somewhat greater than the reported variation. Rough rice yields of the early maturing cultivar calculated by the model were comparable with the reported data in terms of both absolute value and inter -annual variation. But those of the mid season cultivar showed overestimation. After running the simulation model runs with 1997 weather data for 168 CZU's, rough rice yields of the 168 CZU's calculated by the model were aggregated into corresponding 33 counties by acreage-weighting to facilitate direct comparison with the reported statistics from the Ministry of Agriculture and Forestry. The simulation results were good at 22 out of the 26 counties with reportedly increasing yield trend with respect to the past 9 years average.

• Journal of KIISE:Databases
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• v.33 no.4
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• pp.372-383
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• 2006

Among the approaches to image database management, content-based image retrieval (CBIR) is viewed as having the best support for effective searching and browsing of large digital image libraries. Typical CBIR systems allow a user to provide a query image, from which low-level features are extracted and used to find 'similar' images in a database. However, there exists the semantic gap between human visual perception and low-level representations. An effective methodology for overcoming this semantic gap involves relevance feedback to perform feature re-weighting. Current approaches to feature re-weighting require the number of components for a feature representation to be the same for every image in consideration. Following this assumption, they map each component to an axis in the n-dimensional space, which we call the metric space; likewise the feature representation is stored in a fixed-length vector. However, with the emergence of features that do not have a fixed number of components in their representation, existing feature re-weighting approaches are invalidated. In this paper we propose a feature re-weighting technique that supports features regardless of whether or not they can be mapped into a metric space. Our approach analyses the feature distances calculated between the query image and the images in the database. Two-sided confidence intervals are used with the distances to obtain the information for feature re-weighting. There is no restriction on how the distances are calculated for each feature. This provides freedom for how feature representations are structured, i.e. there is no requirement for features to be represented in fixed-length vectors or metric space. Our experimental results show the effectiveness of our approach and in a comparison with other work, we can see how it outperforms previous work.

• Spatial Information Research
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• v.23 no.5
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• pp.53-64
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• 2015

Several countries have built National Spatial Data Infrastructure (NSDI) for information sharing among various fields. One of the important factors of NSDI is framework data, which is the most commonly used geospatial data across various fields. Previous studies on the framework data suggest components based on frequency survey and case study. However, such research methods do not have objectivity in setting the components of the framework data. This research uses factor analysis with 104 medium-level layers from the most widely used National Base Map and 5 layers from the other sources including cadastre and aerial image. Each layer is scaled with usage level as four different patterns of 1) background data, 2) reference data, 3) base data, and 4) other data, respectively. The analysis results show that the layers are grouped into 5 to 7 factors according to the patterns. ANOVA reveals that the mean differences between the factors with high values and the other factors with low values under each pattern are statistically significant. Such high value factors under each pattern consist of similar layers, close to identical, with those under the other categories. This research proposes framework data system, including transportation, building, hydrography, elevation, administrative district, digital orthoimagery, geodetic control, and cadastral based on the analysis results. Proposed framework in this research will be a basis of establishing spatial data sharing system. For sharing proposed framework data in various fields, these data must be established and distributed as actual standard and also related future researches should be performed.

• Spatial Information Research
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• v.16 no.1
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• pp.19-32
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• 2008

Usually in South Korea, land cover type and topographic undulation are frequently changed even in a narrow area. However, most of researches using aerial LIDAR(LIght Detection And Ranging) data in abroad had been acquired in the study areas to be changed infrequently. This research was performed to explore reconstruction methodologies of 3D surface models considering the distribution of land cover type and topographic undulation. Composed of variously undulatory forests, rocky river beds and man-made land cover such as streets, trees, buildings, parking lots and so on, an area was selected for the research. First of all, the area was divided into three zones based on land cover type and topographic undulation using its aerial ortho-photo. Then, aerial LIDAR data was clipped by each zone and different 3D modeling processes were applied to each clipped data before integration of each models and reconstruction of overall model. These kinds of processes might be effectively applied to landscape management, forest inventory and digital map composition. Besides, they would be useful to resolve less- or over-extracted problems caused by simple rectangle zoning when an usual data processing of aerial LIDAR.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.4
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• pp.16-28
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• 2013

Recently the various applications and spectral indices development of airborne hyperspectral imagery(A-HSI) has been increased. Especially the vegetation indices (VIs) were used to verify stress and vigor of vegetation. The VIs needs two or more spectral bands selectively to calculate as NIR(near infrared) and red wavelength. The A-HIS has specific band characteristics as narrow, continues and many. The A-HIS has narrow, continues and many specific band characteristics. That could be make it confuse which of bands could be explained for appropriate vegetation characteristics. If the A-HIS bands is not the same the wavelength with VIs' development band setting, then it need a selection adequate for spectral characteristics of target vegetation. Therefore we set 4 substitute bands for NIR and red wavelength respectively and calculated two VIs combined with substitute bands such as NDVI(normalized difference vegetation index) and MSRI(modified simple ratio index). To consider the variation of each VIs, we adapted the image differencing method of change detection technique. Also, we used spectral derivative to identify appropriate bands for spectral characteristics of digital forest cover type map. The result of adequate bands for two VIs selected red #3 as 680.2nm and NIR #2 as 801.7nm. This wavelength was good for any forest type in low variations.

• Journal of Radiation Protection and Research
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• v.30 no.4
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• pp.237-245
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• 2005

The distribution of radionuclides in soil and plants were calculated, assuming an accidental release of radionuclides from Yeonggwang Nuclear Power Plant. The results which show the concentration change with time and regions were displayed by GIS. GIS Included the commercial program, ArcView(ESRI), and a basic digital map of 1:5000 scale for 30km by 30km area around Yeonggwang Nuclear Power Plant. The target material was $^{137}Cs$ in soil around Yeonggwang area. Given denosited $^{137}Cs$ concentrations, ECOREA-II code computed the $^{137}Cs$ concentration of the soil and the plant in the area divided by 16 azimuth, 480 unit cells in total in which the concentrations also varied with time. The results were introduced into the attributed data of previously designed polygon cells in ArcView. In order to display the concentration change with time by monotonic color, the RGB value for ArcView color lamp was controlled. This display is useful for the public to understand the concentration change of radionuclide around Yeonggwang area definitely.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.7
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• pp.761-768
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• 2010

This paper presents an effective method to achieve the wideband waveform for high resolution SAR(Synthetic Aperture Radar) using the frequency multiplication technique. And also this paper analyzes the root causes for the spectral regrowth due to 3rd-order intermodulation in chirp bandwidth expansion scheme using quadrature modulator and frequency multipliers. The amplitude and phase imbalance requirement are defined based on the simulation results in terms of quadrature channel imbalance. This minimizes the degradation of range resolution, peak sidelobe ratio and integrated sidelobe ratio. The wideband chirp generator using the frequency multiplier and memory map scheme was manufactured and the compensation technique was presented to reduce the spectral regrowth of SAR waveform by minimizing the amplitude and phase imbalance. After I and Q channel imbalance adjustment, the carrier level reduces －28.7 dBm to －53.4 dBm. Chirp signal with 150 MHz bandwidth at S-band expands to 600 MHz bandwidth at X-band. The sidelobe levels are reduced by about 8 to 9 dB by compensating the amplitude balance between I and Q channels.

• Korean Journal of Agricultural and Forest Meteorology
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• v.10 no.3
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• pp.94-101
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• 2008

Warming trends during winter seasons in East Asian regions are expected to accelerate in the future according to the climate projection by the Inter-governmental Panel on Climate Change (IPCC). Warmer winters may affect short-term cold hardiness of deciduous fruit trees, and yet phenological observations are scant compared to long-term climate records in the regions. Dormancy depth, which can be estimated by daily temperature, is expected to serve as a reasonable proxy for physiological tolerance of flowering buds to low temperature in winter. In order to delineate the geographical pattern of short-term cold hardiness in grapevines, a selected dormancy depth model was parameterized for "Campbell Early", the major cultivar in South Korea. Gridded data sets of daily maximum and minimum temperature with a 270m cell spacing ("High Definition Digital Temperature Map", HDDTM) were prepared for the current climatological normal year (1971-2000) based on observations at the 56 Korea Meteorological Administration (KMA) stations and a geospatial interpolation scheme for correcting land surface effects (e.g., land use, topography, and site elevation). To generate relevant datasets for climatological normal years in the future, we combined a 25km-resolution, 2011-2100 temperature projection dataset covering South Korea (under the auspices of the IPCC-SRES A2 scenario) with the 1971-2000 HD-DTM. The dormancy depth model was run with the gridded datasets to estimate geographical pattern of change in the cold-hardiness period (the number of days between endo- and forced dormancy release) across South Korea for the normal years (1971-2000, 2011-2040, 2041-2070, and 2071-2100). Results showed that the cold-hardiness zone with 60 days or longer cold-tolerant period would diminish from 58% of the total land area of South Korea in 1971-2000 to 40% in 2011-2040, 14% in 2041-2070, and less than 3% in 2071-2100. This method can be applied to other deciduous fruit trees for delineating geographical shift of cold-hardiness zone under the projected climate change in the future, thereby providing valuable information for adaptation strategy in fruit industry.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6227-6235
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• 2015

The HUD has recently been downsized due to the development of micro display and LED technology as a see through information display device, gradually expands the application areas. In this paper, using a DLP micro display device designed a compact head-up display(HUD) optical system for biocular observation of the image exhibition area 5 inches. It was analyzed for each design element of the optical system in order to design a compacted HUD. DLP, projection optical system and concave image combiner were discussed the design approach and the characteristics. Through a connection structure analysis of each optical system, detailed design specifications were set up and designed the optical system in detail. Put a folded configuration in the form of a white diffuse reflector between the projection lens and concave image combiner was designed to be independent, respectively. Distance of the projected image is adjustable up to approximately 2m ~ infinity and observation distance is 1m. Resolution could be recognized by 1 ~ 2pixels in HD($1,280{\times}720pixels$) class, various characters and symbols could be read. In addition, color navigation map, daytime video camera and thermal imaging cameras can be displayed.