• Geophysics and Geophysical Exploration
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• v.17 no.1
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• pp.21-27
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• 2014

We analyzed response patterns of test field data acquired with new small loop electromagnetic (EM) system using three-dimensional (3D) electromagnetic modeling code. The size and shape of a conductor was adopted as experimental parameters for EM modeling to understand influencing factors of the response patterns due to a metallic object on the seafloor. Obtaining the responses for four models of difference sizes and shapes through 3D EM modeling, we confirmed that the shape of the object have a more critical factor on the response pattern than size. We also calculated "ppm" values with respect to different altitudes of the sensor and source frequencies. The modeling results show that the consistency of sensor altitude is important and imaginary part of ppm response is more sensitive than real part. We also visualized the contour map of the real and imaginary part of ppm value as a function of frequency and altitude so that we can estimate proper altitude for source frequency band of our survey system. The results of this paper are anticipated to give proper parameters in survey construction for seafloor massive sulfide deposit.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.5
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• pp.322-330
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• 2020

Modeling for outliers in time series was carried out using the MSL and extreme high, low tide levels (EHL, HLL) data set in the Busan and Mokpo stations. The time-series model is seasonal ARIMA model including the components of the AO (additive outliers) and LS (level shift). The optimal model was selected based on the AIC value and the model parameters were estimated using the 'tso' function (in 'tsoutliers' package of R). The main results by the model application, i.e.. outliers and level shift detections, are as follows. (1) The two AO are detected in the Busan monthly EHL data and the AO magnitudes were estimated to 65.5 cm (by typhoon MAEMI) and 29.5 cm (by typhoon SANBA), respectively. (2) The one level shift in 1983 is detected in Mokpo monthly MSL data, and the LS magnitude was estimated to 21.2 cm by the Youngsan River tidal estuary barrier construction. On the other hand, the RMS errors are computed about 1.95 cm (MSL), 5.11 cm (EHL), and 6.50 cm (ELL) in Busan station, and about 2.10 cm (MSL), 11.80 cm (EHL), and 9.14 cm (ELL) in Mokpo station, respectively.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.3
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• pp.337-342
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• 2014

This paper is aims to build the advancement structural model of GICOMS through identification of required system and improvement for implementation of e-Navigation. We derived nine improvement subject for model of advanced GICOMS through the analysis of problems for GICOMS and brainstorming with expert in the maritime safety. And we analyzed the structure of nine improvement subject using by FSM(Fuzzy Structural Modeling) method, and proposed a structural model that to grasp the correlation between elements. As a result, we found out that "advancement of GICOMS" is the final goal, and "improvement a system of information production", "improvement a scheme of information providing", "linkage between GICOMS and VTS" and "building global networks for safety cooperation" are located lowest level. Especially, "advancement of GICOMS" is influenced by "advancement function of VMS" and "Activation of usage" on middle level. We suggested that utilizing state-of-the-art IT facilities, equipment and expertise to improve and enhance the user-centered transition such as maritime workers for advancement of GICOMS based on proposed structure model.

• Korean Journal of Remote Sensing
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• v.22 no.6
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• pp.519-531
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• 2006

Sea surface height (SSH) around fe Korean Peninsula was investigated as a rising rate of $3.89mm\;yr^{-1}$ on the average from 1993 to 2005, which is 1.3 times higher rising rate, compared to the world ocean. In the present study, to investigate SSH changes in regional sections of the East Sea, the Yellow Sea, the South Sea, and the Korea Strait, DT-MSLA (Delayed Time-Maps of Sea Level Anomalies) with multi-satellite data (Topex/Poseidon, Jason-1, ERS, Envisat), provided by AVISO (Archiving, Validation and Interpretation of Satellite Oceanographic data), was used. The periodicity in interannual variability was dominant for $4\sim5$ year in summer, and 3 year in winter as well as an increasing trend. The amplitude and phase for the annual and semi-annual mode in SSH and SST were investigated with harmonic analysis. The geographical distribution of amplitudes for comparison of SSH and SST are slightly reverse in southwest-northeast tilted direction. The monthly SST and SSH is highly correlated correlation coefficient about 0.7 with lag of one or two months over the East Sea and the South Sea during June-August. These results suggest that the Kuroshio stream is dominant during summer over these regions.

• Korean Journal of Environmental Biology
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• v.41 no.1
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• pp.60-88
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• 2023

This study was conducted to investigate the vertical distribution and vascular plants in the Gakho mountain. Form the results of three field surveys from May 2022 to September 2022, a total of 478 total taxa, representing 426 species, 11 subspecies, 35 varieties, four forms, and two hybrids were identified, which were categorized in 282 genera and 94 families. We identified the elevational distribution ranges of 398 taxa of vascular plants. Among them, 19 taxa were endemic to Korea, one taxon was identified as a rare plant. The floristic target plants amounted to 72 taxa, specifically two taxa of grade V, two taxa of grade IV, 16 taxa of grade III, 27 taxa of grade II, and 25 taxa of grade I. Further, 71 taxa were identified as northern lineage plants. A total of 19 taxa of alien plants were identified, with a Naturalized Index of 4.0%, an Urbanization Index of 6.6%, and three plants that disturbed the ecosystem. The result of analyzing the pattern of species richness showed a reversed hump shape with minimum richness at mid-high elevation. A cluster analysis showed a high degree of similarity between adjacent elevation sections that are geographically adjacent with similar habitat environments. Warmth index in the Gakho mountain ranged from 57.2℃·month to 84.2℃·month. Our results provide basic data on vascular plants and valuable information on elevational distribution ranges of current plant species in the Gakho mountain, which could serve as a baseline for comparison of the shifts in elevation under future climate change.

• Korean Journal of Remote Sensing
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• v.23 no.6
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• pp.559-566
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• 2007

The generation of precise digital elevation model (DEM) is very important in coastal area where time series are especially required. Although a LIDAR system is useful in coastal regions, it is not yet popular in Korea mainly because of its high surveying cost and national security reasons. Recently, precise DEM has been made using radar interferometry and waterline methods. One of these methods, spaceborne imaging radar interferometry has been widely used to measure the topography and deformation of the Earth. We acquired ALOS PALSAR FBD mode (Fine Beam Dual) data for evaluating the quality of interferograms and their coherency. We attempted to construct DEM using ALOS PALSAR pairs - One pair is 2007/05/22 and 2007/08/22, another pair is 2007/08/22 and 2007/10/22 with respective perpendicular baseline of 820 m, 312m and respective height sensitivity of 75 m and 185m at southern of Ganghwa tidal flat, Siwha- and Hwaong-lake over west coastal of Korea peninsula. Ganghwa tidal flat has low coherence between 0.3 and 0.5 of 2007/05/22 and 2007/08/22 pair. However, Siwha-lake and Hwaong-lake areas have a higher coherence value (From 0.7 and 0.9) than Ganghwa tidal area. The reason of difference coherence value is tidal condition between tidal flat area (Ganghwa) and reclaimed zone (Siwha-lake and Hwaong-lake). Therefore, DEM was constructed by ALOS PALSAR pair over Siwha-lake and Hwaong-lake. If the temporal baseline is enough short to maintain the coherent phases and height sensitivity is enough small, we will be able to successfully construct a precise DEM over coastal area. From now on, more ALOS PALSAR data will be needed to construct precise DEM of West Coast of Korea peninsular.

• Korean Journal of Environment and Ecology
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• v.33 no.4
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• pp.378-401
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• 2019

This study generated a list of plants in eight sections from the Baekdansa ticket office (874m) to Cheonjedan (1,560m) divided in the interval of 100m above sea level to examine the species diversity patterns and distribution changes of the vascular plants at different altitudes in Taebaeksan National Park. Four site surveys found a total of 385 taxa: 89 families, 240 genera, 345 species, 5 subspecies, 34 varieties, and 1 form. A result of analyzing the change of species diversity along elevational gradients showed that it decreased with increasing elevation and then increased from a certain section. A result of analyzing habitat affinity types showed that the proportion of forest species increased with increasing elevation. On the other hand, the ruderal species appeared at a high rate in the artificial interference section. A result of comparing the proportion of woody and herb plants showed that the woody plants gradually increased with elevation and rapidly decreased in the artificial interference section. On the other hand, the herb plants showed the opposite trend. A result of analyzing the change of distribution of species according to altitude with the DCA technique showed that the vascular plants were divided into three groups according to the elevation in order on the I axis with the boundaries at 900m and 1,300m above sea level. The arrangement of each stand from right to left along the altitude on the I axis with a significant correlation with warmth index (WI) confirmed that the temperature change along the altitude could affect the distribution of vascular plants, composition, and diversity. Therefore, the continuous monitoring is necessary to confirm ecological and environmental characteristics of vegetation, distribution ranges, changes of habitat. We expect that the results of this study will be used as the basic data for establishing the measurement measures related to the preservation of biodiversity and climate change.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.2
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• pp.165-173
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• 2011

Generally, A acquisition of the target is affected by the detector performance and whether it is covered with features or not. This paper represented the comparative analysis of the detection probability for DEM and DSM, when we used by the infrared surveillance device. In the first place, we c1assified as the visible area and invisible area for DEM and DSM, and obtained the acquisition probability values using the ACQUIRE mode. We have known that The Detection Probability of the DSM is very lower than the DEM and is rising when elevates the height value of the detection point.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1085-1093
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• 2010

This paper proposes a multiple filter for reduction of received signal fluctuation and enhancement of step altitude edge detection in FMCW radar altimeter. The proposed filter was composed of alpha-trimmed mean filter, frequency variation limiter, and 1/3 order static filter. Simulations by analysis of received signal show that the proposed filter provides better performance than moving average and standard median filters with error reduction. In particular, the proposed filter was improved in the ability of reducing fluctuation for ground hovering.

• Korean Journal of Environment and Ecology
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• v.4 no.1
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• pp.44-50
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• 1990

To investigate edge vegetation structure in the Mt. Sokri National Park, field survey was executed in August. 1990 and the result are as follows. Dominant edge species by crown-layer and smilarity of species composition seemed to be affected by existing upper layer vegetation, altitude aspect and physiographical location. and the edge vegetation at summit was severely different with one of the other environmental types. Species diversity of edge vegetation was highest at Northern midslope, lowest at Southern mid-slope. and Acer pseudo-sieboldiamun var. koreanum was appeared as a dominant species at all environmental types. Frequency classes of edge species were different by altitude, aspect, physiographicallocation. Acer pseudo-sieboldiamun var, koreanum, Quercus mongolica, Fraxinus rhynchophylla, Lespedeza maximowiczii, Weigela subsessilis showed high frequency class at all environmental condition.