• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.4
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• pp.325-338
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• 2016

Properties of aggregation and spatial distribution of fish were examined based on three lines in the South Sea of Korea using three frequencies (18, 38, and 120 kHz) of a scientific echosounder. The vertical distribution of fish was displayed using acoustic biomass namely nautical area scattering coefficient (NASC). As a result, at 120 kHz high NASC showed from water surface to 20 meters in deep while at 18 and 38 kHz very high NASC presented in 70 ~ 90 meters in depth, especially at line 3. Among three lines, the line 2 had lowest NASC. The horizontal distribution of fish using three frequencies together exhibited high NASC between the eastern South Sea and center of South Sea. In especial, NASC ($801{\sim}1,920m^2/n{\cdot}mile^2$) was observed along coastal waters from Busan to Tongyeong, Geoje, and Namhae. In regard with the property of aggregation of fish schools, the volume back-scattering strength ($S_V$) of three lines presented close each other, however, the range of $S_V$ in the line 2 was shortest (-53.5 ~ -43.4 dB). The average distributional depth was deep in the order of L3 ($32.8{\pm}9.0m$), L1 ($45.2{\pm}9.5m$), L2 ($49.7{\pm}5.6m$). The average altitude was high in the order of L3 ($13.4{\pm}10.3m$), L1 ($17.0{\pm}12.6m$), L2 ($56.7{\pm}5.6m$). The average length, thickness, and area were large in the order of L1, L3, and L2. This means that small sized fish schools were distributed near water surface in the line 2 while relatively large and similar sized fish aggregations between line 1 and line 3 appeared however, fish schools at line 3 had lower distributional depth and smaller compared to those at line 1. Acoustic data were visualized for demonstrating the entire circumstances of survey area. Additionally, there was no correlation between acoustic and trawl results.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.2
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• pp.30-38
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• 2002

In this paper, we propose a new method for image coding which efficiently use the relationship between the properties of spatial image and its wavelet transform. Firstly, an original image is decomposed into several layers by the wavelet transform, and simultaneously decomposed into 2$^n$$\times$2$^n$blocks. Each block is classified into two regions according to their standard deviation, i.e., low activity region(LAR) and high activity region(HAR). The region with low frequency in spatial domain does not only appears as zero regions in wavelet frequency domain like HL, LH, and HH but also gives little influence to the quality of reconstructed image. The other side, the high frequency regions are related to significant coefficients which gives much influence to image reconstruction. In this paper, we propose a image coding method to obtain high compression rate at low bit rate by these properties. The LAR region is encoded by LAR coding method which is proposed in this paper, the HAR by a technique similar to bitplane coding in hierarchical tree. Simulation results show that th,$\boxUl$ proposed coding method has better performance than EZW and SPIHT schemes in terms of image quality and transmitted bit rates, can be successfully applied to the application areas that require of progressive transmission.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.143-148
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• 2012

Sustainable agriculture requires reliable information on the spatial distribution of the soil chemical properties for effective management of paddy fields. In order to provide adequate soil nutritional information for environmental-friendly agriculture, we investigated the soil chemical properties for 260 paddy soils sampled in Gyeongnam Province from 1999 to 2011 by four years of interval. Soil chemical properties of pH, organic matter, available phosphate and silicate, exchangeable potassium, calcium, and magnesium contents were analyzed. The pH value, organic matter, available phosphate and silicate, and exchangeable calcium and magnesium in paddy soils were significantly elevated in 2011 compared to 1999. The excessive levels of organic matter and available phosphate in paddy soils were detected in 2011. The soil available phosphate was highest in mountain foot-slope (p<0.05) and the soil organic matter was highest in diluvial terrace (p<0.05). It revealed that the soil available phosphate was the responsible factor for the differentiation of soil chemical properties by the topography in paddy soils.

• Geophysics and Geophysical Exploration
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• v.7 no.2
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• pp.109-116
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• 2004

Petroleum reservoir characterization is a process for quantitatively describing various reservoir properties in spatial variability using all the available field data. Porosity and permeability are the two fundamental reservoir properties which relate to the amount of fluid contained in a reservoir and its ability to flow. These properties have a significant impact on petroleum fields operations and reservoir management. In un-cored intervals and well of heterogeneous formation, porosity and permeability estimation from conventional well logs has a difficult and complex problem to solve by conventional statistical methods. This paper suggests an intelligent technique using fuzzy logic and neural network to determine reservoir properties from well logs. Fuzzy curve analysis based on fuzzy logics is used for selecting the best related well logs with core porosity and permeability data. Neural network is used as a nonlinear regression method to develop transformation between the selected well logs and core analysis data. The intelligent technique is demonstrated with an application to the well data in offshore Korea. The results show that this technique can make more accurate and reliable properties estimation compared with previously used methods. The intelligent technique can be utilized a powerful tool for reservoir characterization from well logs in oil and natural gas development projects.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.125-135
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• 2008

The purpose of this study is to quantify the erosion parameters of cohesive sediments in Keum Estuary. This study also involves the examinations on the local/seasonal variation of them in Keum Estuary and on their spatial variation comparing with those of other sites. As erosional properties of cohesive sediments are in general influenced largely by the physico-chemical properties of cohesive sediments themselves, this study also involves the qualitative analyses on the impact by the physico-chemical properties. Erosion tests have been performed under the uniform bed condition using the Chonbuk annular flume and total 16 tests have been carried out with various bed densities and bottom shear stresses. Experimental results show that the critical shear stress for erosion varies in the range of $0.19{\sim}0.41N/m^2$ and the coefficient of erosion rate varies in the range of $54.26{\sim}7.70mg/cm^2{\cdot}hr$, over the corresponding bulk-density range of $1.14{\sim}1.38g/cm^3$. While erosion parameters estimated for Keum estuary sediments are found to be remarkably different in quantity compared with those for cohesive sediments from other sites, their local/seasonal variabilities within Keum Estuary are found to be insignificant.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.1
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• pp.141-153
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• 2016

The increase in frequency and scale of natural disasters is the typical negative examples of the global climate change and the change of the human living environment in cities. The damage caused by natural disasters in particular including human and physical damage is directly linked to the safety and properties of citizens. Besides, the damage may occur to SOC facilities directly or indirectly. The SOC facilities damaged by disasters cause infringement of citizens safety rights. Therefore, a plan to provide prompt and effective risk map information by linking a 3D disaster information display system, which handles the information of the damage that may occur to SOC facilities such as bridges, beams, and dams at the time of disasters, with an on-site assistance application is suggested in this study. The prompt provision of risk map information is defined as a dynamic expression technology in this study. Also, disaster information is processed and compressed with a module developed to be linked organically to a system that displays disaster information, a proliferation system that can use the information on site, and a DB system that constructs a relationship with the information. Based on the module, the effective disaster information compression plan will be prepared, and the prompt information transmission system will be secured in the future.

• Journal of the Korean GEO-environmental Society
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• v.19 no.4
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• pp.33-38
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• 2018

The internal erosion due to poor compaction of the material was the main cause of collapse of the embankment in Korea. The assessment of the compaction state of the dam body was a very important check in the safety diagnosis of the embankment. In this study, the correlation between dynamic cone penetration test and plate loading test which is the most typical compaction evaluation technique was analyzed to verify the applicability of the dynamic cone penetration test in evaluating the compaction state of the dam body. The standard penetration tests were carried out six times to define soil properties and depth of the test site. The spatial distributions were obtained by the Kriging method after 15 times of plate loading tests and 47 times of dynamic cone penetration tests. The Pearson correlation coefficient between the spatial distribution of the plate loading test and the dynamic cone penetration test spatial distribution at the constant penetration depth was calculated. The load distribution in the plate loading test and the blow counts at penetration depths of 5 cm, 10 cm and 15 cm in the dynamic cone penetration test showed a weak positive correlation.

• ALGAE
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• v.31 no.3
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• pp.231-241
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• 2016

We examined the genetic diversity and abundance of picocyanobacteria using barcoded amplicon sequencing approaches and flow cytometry in the East Sea and the East China Sea to determine the distribution patterns of diversity during spring in seas adjacent to the Korean Peninsula. Synechococcus clades I and IV, which have been known as cold-adapted ecotypes, dominated at most stations. However, the relative abundances of the two dominant clades differed in their spatial patterns. Clade I was exclusively dominant in the shelf area of the East China Sea and the north East Sea. However, the dominant genotypes belonging to clade I had different spatial distributions in the two areas and responded oppositely to seawater temperature. The dominance of distinct genotypes under the different ecological conditions suggests the presence of ecologically different ecotypes within the clade. Abundances of clade IV were greater than those of clade I at most stations in the southwest East Sea, showing an apparently different pattern from that of the other areas. A warm-water adapted clade II was observed at significant levels only at stations located in the eastern East China Sea affected by a branch of the warm Kuroshio Current. These results suggest that the physicochemical properties of influencing water masses play an important role in determining the distribution of Synechococcus genotypes.

• Journal of the Korean association of regional geographers
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• v.2 no.2
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• pp.183-196
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• 1996

The purpose of this paper is to explore the possibility of automatic extraction of line feature from Satellite image. The first part reviews the relationship between spatial filtering and cartographic interpretation. The second part describes the principal operations of high frequency filters and their properties, the third part presents the result of filtering application to the SPOT Panchromatic image of the Chinju city. Some experimental results are given here indicating the high feasibility of the filtering technique. The results of the paper is summarized as follows: Firstly the good all-purposes filter dose not exist. Certain laplacian filter and Frei-chen filter were very sensitive to the noise and could not detect line features in our case. Secondly, summary filters and some other filters do an excellent job of identifying edges around urban objects. With the filtered image added to the original image, the interpretation is more easy. Thirdly, Compass gradient masks may be used to perform two-dimensional, discrete differentiation directional edge enhancement, however, in our case, the line featuring was not satisfactory. In general, the wide masks detect the broad edges and narrow masks are used to detect the sharper discontinuities. But, in our case, the difference between the $3{\times}3$ and $7{\times}7$ kernel filters are not remarkable. It may be due to the good spatial resolution of Spot scene. The filtering effect depends on local circumstance. Band or kernel size selection must be also considered. For the skillful geographical interpretation, we need to take account the more subtle qualitative information.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.4
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• pp.234-246
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• 2007

The role of macropore in the hydrological processes is important at the hillslope scale. Developments and distribution of macropores have not been investigated in conjunction with the characteristics of the hillslope such as topography, soil property, and soil moisture. In this study, macropore properties, such as macropore flow and saturation hydraulic conductivity were measured at a hillslope located in Gwangneung Research Forest, Pochun-gun, Gyeonggi-do, South Korea. An intensive field survey provided a refined Digital Elevation Model (DEM) for surface and subsurface topography. Spatial distributions of upslope area and topographic index were obtained through the digital terrain analysis. The total number of monitoring points was 22, and the selected points were distributed along the transect of the digital contour map. Vertical fluxes through macropores were measured using a tension infiltrometer at the depth of 0.1 m from the surface. Spatial and temporal distributions of soil moisture were obtained using an on-line measurement system, TRASE, installed in the study area. Soil moisture for the aforementioned points was measured at 0.1 and 0.3m depths below the surface. The results from tension infiltrometer experiments present that the macropore flows ranged between 21 and 94%, and the measured macroporosities varied from 1.4 to 47%. Macropore flows and macroporosities tended to increase as the measurement location moved to downslope. The ability for water conduction through macropores becomes increasingly developed as the location approaches the outlet of the hillslope.