• Journal of the Institute of Convergence Signal Processing
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• v.15 no.4
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• pp.176-182
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• 2014

This paper introduces the development of global fringe search (GFS) software for preprocessing of Daejeon Correlator. In case of the VLBI observation, a observer conducts the observation for the reference sources with strong and point-like radio stars on schedule in order to confirm the well-observedness of the radio source by the radio telescope. The correlator performs the correlation for the reference sources to detect the fringe completely. We developed the GFS software by calculating the precise delay time between each observatory based on specific observatory. Then, this software calculates the precise delay time by using the delay model (correlator model) of reference source and information of time offset between the Hydrogen Maser frequency standard and GPS (Global Positioning System) clock located in each observatory through the correlation preprocessing. In order to confirm the performance of the developed software, experiments were carried out for the reference sources and target sources observed by the KaVA (KVN and VERA Array). Experimental results show that the GFS software has effectively good performance by finding the precise delay time offset according to the comparison between the compensated delay time offset and one without compensation.

• Journal of the Korean GEO-environmental Society
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• v.13 no.10
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• pp.25-32
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• 2012

The application of electrical resistivity, which is related to charge mobility, has increased in the field of geotechnical engineering for the detection of underground cavern, faults and subsurface pollution level. The purpose of this study is to investigate the variation of electrical resistivity due to temperature change. Sand-silt mixture specimens prepared in the square freezing nylon cell are frozen in the frozen chamber. Four electrodes are attached on the four side walls of the freezing cell for the measurement of electrical resistance during temperature change. Electrical resistances of sand-silt mixtures with different degrees of saturation (0%, 2.5%, 5%, 10%, 20%, 40%, 60% and 100%) are measured as the temperature of specimens decrease from $20^{\circ}C$ to $-10^{\circ}C$. The electrical resistances determined by Ohm's law are transformed into the electrical resistivity by calibration. Experimental results show that the higher degree of saturation, the lower electrical resistivity at $20^{\circ}C$. Electrical resistivity gradually increases as the temperature decrease from $20^{\circ}C$ to $0^{\circ}C$. For the specimens with the degree of saturation of 15% or higer, electrical resistivity dramatically changes near the temperature of $0^{\circ}C$. In addition, very high electrical resistivity is observed regardless of the degree of saturation if the specimens are frozen. This study provides the fundamental information of electrical resistivity according to the soil freezing and temperature change demonstrates that electrical resistivity be a practical method for frozen soil investigation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.2
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• pp.121-131
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• 2007

Despite the close linkage in changes between the ecological and hydrological processes in forest ecosystems, an integrative approach has not been incorporated successfully. In this study, based on the vegetation and hydrologic data of the Gwangneung headwater catchment with the Geographic Information System, we attempted such an integrated approach by employing the Regional Hydro-Ecologic Simulation System (RHESSys). To accomplish this, we have (1) constructed the input data for RHESSys, (2) developed an integrated calibration system that enables to consider both ecological and hydrological processes simultaneously, and (3) performed sensitivity analysis to estimate the optimum parameters. Our sensitivity analyses on six soil parameters that affect streamflow patterns and peak flow show that the decay parameter of horizontal saturated hydraulic conductivity $(s_1)$ and porosity decay by depth (PD) had the highest sensitivity. The optimization of these two parameters to estimate the optimum streamflow variation resulted in a prediction accuracy of 0.75 in terms of Nash-Sutcliffe efficiency (NSec). These results provide an important basis for future evaluation and mapping of the watershed-scale soil moisture and evapotranspiration in forest ecosystems of Korea.

• Journal of Korean Society of Forest Science
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• v.99 no.3
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• pp.285-291
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• 2010

Since 2006, the $5^{th}$ National Forest Inventory (NFI) has been implemented to provide forest resources statistics at the national level and at the county level as well. However, it needs a small-area estimator for estimating forest statistics at the county-level due to a small number of samples collected within a county. This study was conducted to evaluate the applicability of a geographical-based synthetic estimator for estimating forest growing stock volumes at the county level. The NFI-field plots surveyed were post-stratified into three forest cover types. In the synthetic estimator, field plots within a geographical-based super-county for each county were used to estimate stratum weights and stratum mean volumes. It was resulted that estimated stratum weights using the synthetic estimation were significantly differ from forest cover maps. The standard errors of estimated mean by the synthetic estimation that ranged from ${\pm}3.5\;m^3$/ha to ${\pm}7.7\;m^3$/ha were more smaller than those (${\pm}7.8\;m^3/ha{\sim}{\pm}24.7\;m^3/ha$) by the direct estimation. This means that the synthetic estimation is possible to provide more precise estimates of mean volumes.

• Journal of Convergence for Information Technology
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• v.10 no.7
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• pp.215-222
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• 2020

The purpose of this study was to investigate the relationship between mastication problems and quality of life among middle-aged Koreans. The study used data from the 6^th Korea National Health and Nutrition Examination Survey(KNHANES VI). Data on 7,125 respondents aged 40 to 64 were analyzed to evaluate quality of life as measured by the Euro Quality of Life-5D(EQ-5D) index and mastication problems. Quality of life was classified as either low or high based on 0.96. The data were analyzed using SPSS 20.0. The prevalence of low quality of life was significantly higher in the group with mastication problems, at 41.9%, than in the group with no mastication problems(24.4%). After adjusting the general characteristics and oral health status, the odds of a lower quality of life were higher in the those with mastication problems, at 1.77 (95% CI: 1.53-2.06), than in those with no mastication problems. Mastication problem was significantly related to the quality of life. The studies are needed to reflect the oral factors in diverse age groups.

• Spatial Information Research
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• v.9 no.2
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• pp.291-307
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• 2001

In today's environmental engineering practice, many technologies such as GIS have been adopted to analyze chemical and biological process in water bodies and pollutants movements on the land surface. However, the linkage between spatially represented land surface pollutants and the in-stream processes has been relatively weak. This lack of continuity needs to develop a method in order to link the spatially-based pollutant source characterization with the water quality modeling. The objective of this thesis was to develop a two-way(forward and backward) link between ArcView GIS software and the USEPA water quality model, WASP5. This thesis includes a literature review, the determination of the point source and non-point source loadings from WASP5 modeling, and the linkage of a GIS with WASP5 model. The GIS and model linkage includes pre-processing of the input data within a GIS to provide necessary information for running a model in the forms of external input files. The model results has been post-processed and stored in the GIS database to be reviewed in a user defined form such as a chart, or a table. The interface developed from this study would provide efficient environment to support the easier decision making form water quality management.

• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.322-331
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• 2007

In this study, electrical resistivity tomography (ERT) were conducted to find the mineralized zone at the Geumpung mine in Dojeon-ri, Susan-myeon, Jecheon-si, Chungcheongbuk-do. The deviation of the inclined borehole was measured to obtain the exact positions of the electrodes for correcting apparent resistivity values from ERT. Geophysical loggings such as resistivity and natural gamma were conducted to obtain the properties of the material near the borehole. Measurements of the physical properties of the cores, such as porosity, water content, density, susceptibility, resistivity were performed to analyze the correlation between physical properties and resistivity. Grade analysis for core sample was also conducted to identify relationship between grade and resistivity. Rock property analysis shows that the resistivity is more dominated by susceptibility and grade than by porosity and water content in the mineralized zone. The results of ERT are well consistent with geophysical logging data and geologic column. So ERT is powerful method to identify conductive mineralized zone.

• Journal of Korea Water Resources Association
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• v.45 no.7
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• pp.729-741
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• 2012

Among the methods of precipitation data acquisition, a rain gauge station has a distinctive advantage of direct measurement of rainfall itself, but multiple stations should be installed in order to obtain areal precipitation data required for hydrological analysis. On the other hand, a rainfall radar may provide areal distribution of rainfall in real time though it is an indirect measurement of radar echoes on rain drops. Rainfall radars have been shown useful especially for forecasting short-term localized torrential storms that may cause catastrophic flash floods. CAPPI (Constant Altitude Plan Position Indicator), which is one of the several types of radar rainfall image data, has been provided on the Internet in real time by Korea Meteorological Administration (KMA). It is one of the most widely available rainfall data in Korea with fairly high level of confidence as it is produced with bias adjustment and quality control procedures by KMA. The objective of this study is to develop an improved way to extract quantitative rainfall data applicable to even very small watersheds from CAPPI using CIVCOM, which is a new image processing method based on a vector-based scheme proposed in this study rather than raster-based schemes proposed by other researchers. This study shows usefulness of CIVCOM through comparison of rainfall data produced by image processing methods including traditional raster-based schemes and a newly proposed vector-based one.

• Journal of the Korea Computer Graphics Society
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• v.21 no.1
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• pp.1-11
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• 2015

Researchers have developed virtual reality environments to provide audience with more visually immersive experiences than previously possible. One of the most popular solutions to build the immersive VR space is a multi-projection technique. However, utilization of multiple projectors requires large spaces, expensive cost, and accurate geometry calibration among projectors. This paper presents a novel omnidirectional projection system with a single projector and a single spherical mirror.We newly designed the simple and intuitive calibration system to define the shape of environment and the relative position of mirror/projector. For successful image projection, our optimized omnidirectional image generation step solves image distortion produced by the spherical mirror and a calibration problem produced by unknown parameters such as the shape of environment and the relative position between the mirror and the projector. Additionally, the focus correction is performed to improve the quality of the projection. The experiment results show that our method can generate the optimized image given a normal panoramic image for omnidirectional projection in a rectangular space.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.6
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• pp.749-754
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• 2011

In this study, we propose the design of optimized pRBFNNs-based face recognition system using two-dimensional Image and ASM algorithm. usually the existing 2 dimensional face recognition methods have the effects of the scale change of the image, position variation or the backgrounds of an image. In this paper, the face region information obtained from the detected face region is used for the compensation of these defects. In this paper, we use a CCD camera to obtain a picture frame directly. By using histogram equalization method, we can partially enhance the distorted image influenced by natural as well as artificial illumination. AdaBoost algorithm is used for the detection of face image between face and non-face image area. We can butt up personal profile by extracting the both face contour and shape using ASM(Active Shape Model) and then reduce dimension of image data using PCA. The proposed pRBFNNs consists of three functional modules such as the condition part, the conclusion part, and the inference part. In the condition part of fuzzy rules, input space is partitioned with Fuzzy C-Means clustering. In the conclusion part of rules, the connection weight of RBFNNs is represented as three kinds of polynomials such as constant, linear, and quadratic. The essential design parameters (including learning rate, momentum coefficient and fuzzification coefficient) of the networks are optimized by means of Differential Evolution. The proposed pRBFNNs are applied to real-time face image database and then demonstrated from viewpoint of the output performance and recognition rate.