• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.1
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• pp.58-66
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• 2010

In this paper, we have constructed high-resolution topographical map of macro-tidal Malipo beach through integration of terrestrial LiDAR measurement and MBES survey data at inter-tidal zone. To acquire the enough information of inter-tidal zone, we have done terrestrial LiDAR measurement mounted on the roof of vehicle with DGPS through go-stop-scan method at the ebb tide and MBES depth surveying with tide gauge and eye staff measurement for tide correction and MSL calculation at the high tide all together. To integrate two kinds of data, we have unified the vertical coordination standard to Incheon MSL. The mean error of overlapped inter-tidal zone is about 2~6 cm. To verify the accuracy of terrestrial LiDAR, RTK-DGPS measurement have done simultaneously and the difference of Z value RMSE is about 4~7 cm. The resolution of Malipo topographical map is 50 cm and it has constructed to DEM (Digital Elevation Model) based on GIS. Now it has used as an input topography information for the storm-surge inundation prediction models. Also it will be possible to use monitoring of beach process through the long-term periodic measurement and GIS-based 3D spatial analysis calculating the erosion and deposition considering with the artificial beach transition and coastal environmental parameters.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.39 no.6
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• pp.483-490
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• 2021

Due to the recent increase in various problems from underground development in urbanized areas, accurate underground facility information management is highly needed. Therefore, in this study, in order to utilize the Integration Map of Underground Goespatial Information in real time on-site, the function of comparing the mutual location of the GPR (Ground Penetration Radar) sensing data and the Integration Map of Underground Goespatial Information, and function of analyze underground facilities, and function of converting surveying data into a shape file through position correction & attribute editing in a 3D space, and the function of submitting the shape file to the Integration Map of Underground Goespatial Information mobile center was defined and developed as a program. In addition, for the on-site application test of the development program, scenarios used at the underground facility real-time survey site and GPR exploration site were derived, and four sites in Seoul were tested to confirm that the use scenario worked properly. Through this, the on-site utilization of the program developed in this study could be confirmed, and it would contribute to the confirmation of the quality of Shape-file and the "update automation" of "Integration Map of Underground Goespatial Information". In addition, it is expected that the development program will be further applied to the Underground Facility Map's Accuracy Improvement Diffusion Project' promoted by the MOLIT (Ministry of Land, Infrastructure, and Transport).

• Journal of the Korean Association of Geographic Information Studies
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• v.24 no.4
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• pp.164-173
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• 2021

Recently, as underground space safety issues such as sink hole, ground subsidence and damage to old underground facilities have been increasing in urban areas, the precise management of underground facilities ins more required. Thus, this study developed a function to that, visualize on Integration Map of Underground Geospatial Information a real-time survey data of underground facilities acquired on site or underground facility survey data acquired through on-site survey after underground facility exploration and developed a function convert to surveying-results. In addition, using the on-site survey performance utilization function in connection with the Integration Map of Underground Geospatial Information developed through this study, the surveying -results obtained with the Total-station at the water pipeline burial construction site in Eunpyeong-gu, Seoul are visualized on the Integration Map of Underground Geospatial Information and On-site verification was performed by converting spatial-information performance files and transmitting the Integration Map of Underground Geospatial Information to the mobile center. Based on this, it was possible to verify the work procedure using the surveying-results in the area where the Integration Map of Underground Geospatial Information was built, and to review the direction of future improvement directions.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.4
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• pp.39-58
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• 2019

This study performed the dam watershed storm runoff modeling using GPM(Global Precipitation Measurement) satellite rain and KIMSTORM2(KIneMatic wave STOrm Runoff Model 2) distributed model. For YongdamDam watershed(930㎢), three heavy rain events of 25th August 2014, 11th September 2017, and 26th June 2018 were selected and tested for 4 cases of spatial rainfalls such as (a) Kriging interpolated data using ground observed data at 7 stations, (b) original GPM data, (c) GPM corrected by CM(Conditional Merging), and GPM corrected by GDA(Geographical Differential Analysis). For the 4 kinds of data(Kriging, GPM, CM-GPM, and GDA-GPM), the KIMSTORM2 was calibrated respectively using the observed flood discharges at 3 water level gauge stations(Cheoncheon, Donghyang, and Yongdam) with parameters of initial soil moisture contents, stream Manning's roughness coefficient, and effective hydraulic conductivity. The total average Nash-Sutcliffe efficiency(NSE) for the 3 events and 3 stations was 0.94, 0.90, 0.94, and 0.94, determination coefficient(R²) was 0.96, 0.92, 0.97 and 0.96, the volume conservation index(VCI) was 1.03, 1.01, 1.03 and 1.02 for Kriging, GPM, CM-GPM, and GDA-GPM applications respectively. The CM-GPM and GDA-GPM showed better results than the original GPM application for peak runoff and runoff volume simulations, and they improved NSE, R², and VCI results.

• Geophysics and Geophysical Exploration
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• v.26 no.2
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• pp.52-61
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• 2023

The use of ultra-high-resolution (UHR) seismic surveys to preceisly characterize coastal and shallow structures have increased recently. UHR surveys derive a spatial resolution of 3.125 m using a high-frequency source (80 Hz to 1 kHz). A digital streamer system is an essential module for acquiring high-quality UHR seismic data. Localization studies have focused on reducing purchase costs and decreasing maintenance periods. Basic performance verification and application tests of the developed streamer have been successfully carried out; however, a comparative analysis with the existing benchmark model was not conducted. In this study, we characterized data obtained by using a developed streamer and a benchmark model simultaneously. Tamhae 2 and auxiliary equipment of the Korea Institute of Geoscience and Mineral Resources were used to acquire 2D seismic data, which were analyzed from different perspectives. The data obtained using the developed streamer differed in sensitivity from that obtained using benchmark model by frequency band.However, both type of data had a very high level of similarity in the range corresponding to the central frequency band of the seismic source. However, in the low frequency band below 60 Hz, data obtained using the developed streamer showed a lower signal-to-noise ratio than that obtained using the benchmark model.This lower ratio can hinder the quality in data acquisition using low-frequency sound sources such as cluster air guns. Three causes for this difference were, and streamers developed in future will attempt to reflect on these improvements.

• Korean Journal of Applied Biomechanics
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• v.18 no.2
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• pp.49-58
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• 2008

The purpose of this study was to identify effects of walking speed and a cognitive task during treadmill walking on gait variability. Experiments consisted of 5 different walking speeds(80%, 90%, 100%, 110% and 120% of preferred walking speed) with/without a cognitive task. 3D motion analysis system was used to measure subject's kinematic data. Temporal/spatial variables were selected for this study; stride time, stance time, swing time, step time, double support time, stride length, step length and step width. Two parameters were used to compare stride-to-stride variability with/without cognitive task. One is the coefficient of variance which is used to describe the amount of variability. The other is the detrended fluctuation analysis which is used to infer self-similarity from fluctuation of aspects. Results showed that cognitive task may influence stride-to-stride variability during treadmill walking. Further study is necessary to clarify this result.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.3
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• pp.39-50
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• 2015

This research selected Daegu Metropolitan City representing a combination of natural space and urban space for this case study. To achieve this, a prerequisite was to set up an optimal block size to evaluate landscape diversity of the research site by using a RPR-Area Curve. Further, landscape diversity evaluation was conducted based on land cover map by using FRAGSTATS to analyze spatio-temporal changes. Notably, this research regarded it as the most significant to set forth criteria in order to apply landscape diversity to the development plans of the newtown and outskirt of a city under high pressure development. Results derived from this research are summarized as follows. According to the results derived from establishing the optimal block size, a size about $2km^2$ was analyzed to measure landscape diversity of the research site. Also, according to the results derived from land diversity evaluation based on land cover map, land diversity was highly measured around urban stream such as Nakdong River and Geumho River, and in particular, the value of landscape diversity was measured considerably high around the urban parks. Results derived from analysis on spatio-temporal changes of land diversity demonstrated that a certain level of urban development exerted a positive effect on an increase in land diversity, but consistent urban development lowered a value of landscape diversity. Results derived from regression analysis to set forth the optimal urban space showed that an urban area of a space about $2km^2$ exerted a positive effect at a rate of about 0~43.3% and a negative effect at a rate about 43.3~100%. In conclusion, the results of this research are considered to provide important basic data for future urban and landscape planning. Nonetheless, as only the layout on the 2D plane was analyzed in this research, further research in future is required to complexly consider diverse factors such as height of structure and change in visible real area arising from geographical features.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.2
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• pp.211-221
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• 2012

To utilize omni-directional images acquired by a rotating line camera for indoor spatial information services, we should register precisely the images with respect to an indoor coordinate system. In this study, we thus develop a georeferencing method to estimate the exterior orientation parameters of an omni-directional image - the position and attitude of the camera at the acquisition time. First, we derive the collinearity equations for the omni-directional image by geometrically modeling the rotating line camera. We then estimate the exterior orientation parameters using the collinearity equations with indoor control points. The experimental results from the application to real data indicate that the exterior orientation parameters is estimated with the precision of 1.4 mm and $0.05^{\circ}$ for the position and attitude, respectively. The residuals are within 3 and 10 pixels in horizontal and vertical directions, respectively. Particularly, the residuals in the vertical direction retain systematic errors mainly due to the lens distortion, which should be eliminated through a camera calibration process. Using omni-directional images georeferenced precisely with the proposed method, we can generate high resolution indoor 3D models and sophisticated augmented reality services based on the models.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.172-176
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• 2010

Purpose: The patients' moves occurred at PET/CT scan will cause the decline of correctness in results by resulting in inconsistency of Attenuation Correction (AC) and effecting on quantitative evaluation. This study has evaluated the utility of reconstruction method using AC position changing method when having inconsistency of AC depending on the position change of emission scan after transmission scan in obtaining PET/CT 3D image. Materials and Methods: We created 1 mL syringe injection space up to ${\pm}2$, 6, 10 cm toward x and y axis based on central point of polystyrene ($20{\times}20110$ cm) into GE Discovery STE16 equipment. After projection of syringe with $^{18}F$-FDG 5 kBq/mL, made an emission by changing the position and obtained the image by using AC depending on the position change. Reconstruction method is an iteration reconstruction method and is applied two times of iteration and 20 of subset, and for every emission data, decay correction depending on time pass is applied. Also, after setting ROI to the position of syringe, compared %Difference (%D) at each position to radioactivity concentrations (kBq/mL) and central point. Results: Radioactivity concentrations of central point of emission scan is 2.30 kBq/mL and is indicated as 1.95, 1.82 and 1.75 kBq/mL, relatively for +x axis, as 2.07, 1.75 and 1.65 kBq/mL for -x axis, as 2.07, 1.87 and 1.90 kBq/mL for +y axis and as 2.17, 1.85 and 1.67 kBq/mL for -y axis. Also, %D is yield as 15, 20, 23% for +x axis, as 9, 23, 28% for -x axis, as 12, 21, 20% for +y axis and as 8, 22, 29% for -y axis. When using AC position changing method, it is indicated as 2.00, 1.95 and 1.80 kBq/mL, relatively for +x axis, as 2.25, 2.15 and 1.90 kBq/mL for -x axis, as 2.07, 1.90 and 1.90 kBq/mL for +y axis, and as 2.10, 2.02, and 1.72 kBq/mL for -y axis. Also, %D is yield as 13, 15, 21% for +x axis, as 2, 6, 17% for -x axis, as 9, 17, 17% for +y axis, and as 8, 12, 25% for -y axis. Conclusion: When in inconsistency of AC, radioactivity concentrations for using AC position changing method increased average of 0.14, 0.03 kBq/mL at x, y axis and %D was improved 6.1, 4.2%. Also, it is indicated that the more far from the central point and the further position from the central point under the features that spatial resolution is lowered, the higher in lowering of radioactivity concentrations. However, since in actual clinic, attenuation degree increases more, it is considered that when in inconsistency, such tolerance will be increased. Therefore, at the lesion of the part where AC is not inconsistent, the tolerance of radioactivity concentrations will be reduced by applying AC position changing method.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.2
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• pp.80-98
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• 2023

This study explores the effectiveness of various data preprocessing algorithms for improving subseasonal to seasonal (S2S) climate predictions from six climate forecast models and their Multi-Model Ensemble (MME) using a deep learning-based postprocessing model. A pipeline of data transformation algorithms was constructed to convert raw S2S prediction data into the training data processed with several statistical distribution. A dimensionality reduction algorithm for selecting features through rankings of correlation coefficients between the observed and the input data. The training model in the study was designed with TimeDistributed wrapper applied to all convolutional layers of U-Net: The TimeDistributed wrapper allows a U-Net convolutional layer to be directly applied to 5-dimensional time series data while maintaining the time axis of data, but every input should be at least 3D in U-Net. We found that Robust and Standard transformation algorithms are most suitable for improving S2S predictions. The dimensionality reduction based on feature selections did not significantly improve predictions of daily precipitation for six climate models and even worsened predictions of daily maximum and minimum temperatures. While deep learning-based postprocessing was also improved MME S2S precipitation predictions, it did not have a significant effect on temperature predictions, particularly for the lead time of weeks 1 and 2. Further research is needed to develop an optimal deep learning model for improving S2S temperature predictions by testing various models and parameters.