• Korean Journal of Remote Sensing
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• v.26 no.2
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• pp.87-98
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• 2010

For generating accurate land cover map over the whole Korean Peninsula, post-mosaic classification method is desirable in large area where multiple image data sets are used. We try to derive an optimal mosaic method of multi-temporal Landsat ETM+ scenes for the land cover classification over the Korea Peninsula. Total 65 Landsat ETM+ scenes were acquired, which were taken in 2000 and 2001. To reduce radiometric difference between adjacent Landsat ETM+ scenes, we apply three relative radiometric correction methods (histogram matching, 1st-regression method referenced center image, and 1st-regression method at each Landsat ETM+ path). After the relative correction, we generated three mosaic images for three seasons of leaf-off, transplanting, leaf-on season. For comparison, three mosaic images were compared by the mean absolute difference and computer classification accuracy. The results show that the mosaic image using 1st-regression method at each path show the best correction results and highest classification accuracy. Additionally, the mosaic image acquired during leaf-on season show the higher radiance variance between adjacent images than other season.

• Journal of Ship and Ocean Technology
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• v.10 no.4
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• pp.12-23
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• 2006

In this paper, a numerical study is carried out to investigate the turbulent flow around a twin-skeg container ship model with rudders including propeller effects. A commercial CFD code, FLUENT is used with body forces distributed on the propeller disk to simulate the ship stem and wake flows with the propeller in operation. A multi-block, matching, structured grid system has been generated for the container ship hull with twin-skegs in consideration of rudders and body-force propeller disks. The RANS equations for incompressible fluid flows are solved numerically by using a finite volume method. For the turbulence closure, a Reynolds stress model is used in conjunction with a wall function. Computations are carried out for the bare hull as well as the hull with appendages of a twin-skeg container ship model. For the bare hull, the computational results are compared with experimental data and show generally a good agreement. For the hull with appendages, the changes of the stem flow by the rudders and the propellers have been analyzed based on the computed result since there is no experimental data available for comparison. It is found the flow incoming to the rudders has an angle of attack due to the influence of the skegs and thereby the hull surface pressure and the limiting streamlines are changed slightly by the rudders. The axial velocity of the propeller disk is found to be accelerated overall by about 35% due to the propeller operation with the rudders. The area and the magnitude of low pressure on the hull surface enlarge with the flow acceleration caused by the propeller. The propellers are found to have an effect on up to the position where the skeg begins. The propeller slipstream is disturbed strongly by the rudders and the flow is accelerated further and the transverse velocity vectors are weakened due to the flow rectifying effect of the rudder.

• Hip & pelvis
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• v.30 no.4
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• pp.219-225
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• 2018

Purpose: Ischiofemoral impingement (IFI)-primarily diagnosed by magnetic resonance imaging (MRI)-is an easily overlooked disease due to its low incidence. The purpose of this study was to evaluate the usefulness of false profile view as a screening test for IFI. Materials and Methods: Fifty-eight patients diagnosed with IFI between June 2013 and July 2017 were enrolled in this retrospective study. A control group (n=58) with matching propensity scores (age, gender, and body mass index) were also included. Ischiofemoral space (IFS) was measured as the shortest distance between the lateral cortex of the ischium and the medial cortex of lesser trochanter in weight bearing hip anteroposterior (AP) view and false profile view. MRI was used to measure IFS and quadratus femoris space (QFS). The receiver operating characteristics (ROC), area under the ROC curve (AUC) and cutoff point of the IFS were measured by false profile images, and the correlation between the IFS and QFS was analyzed using the MRI scans. Results: In the false profile view and hip AP view, patients with IFI had significantly decreased IFS (P<0.01). In the false profile view, ROC AUC (0.967) was higher than in the hip AP view (0.841). Cutoff value for differential diagnosis of IFI in the false profile view was 10.3 mm (sensitivity, 88.2%; specificity, 88.4%). IFS correlated with IFS (r=0.744) QFS (0.740) in MRI and IFS (0.621) in hip AP view (P<0.01). Conclusion: IFS on false profile view can be used as a screening tool for potential IFI.

• Korean Journal of Remote Sensing
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• v.36 no.6_2
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• pp.1537-1549
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• 2020

The ground sample distance of KOMPSAT-3 is 0.7 m for panchromatic band, 2.8 m for multi-spectral band, and the swath width of KOMPSAT-3 is 16 km. Therefore, an image of an area wider than the swath width (16 km) cannot be acquired with a single scanning. Thus, after scanning multiple areas in units of swath width, the acquired images should be made into one image. At this time, the necessary algorithm is called image mosaicking or image stitching, and is used for cartography. Mosaic algorithm generally consists of the following 4 steps: (1) Feature extraction and matching, (2) Radiometric balancing, (3) Seamline estimation, and (4) Image blending. In this paper, we have studied an effective seamline estimation method for satellite images. As a result, we can estimate the seamline more accurately than the existing method, and the heterogeneity of the mosaiced images was minimized.

• Korean Journal of Remote Sensing
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• v.37 no.4
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• pp.777-788
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• 2021

Since aerosol has a relatively short duration and significant spatial variation, satellite observations become more important for the spatially and temporally continuous quantification of aerosol. However, optical remote sensing has the disadvantage that it cannot detect AOD (Aerosol Optical Depth) for the regions covered by clouds or the regions with extremely high concentrations. Such missing values can increase the data uncertainty in the analyses of the Earth's environment. This paper presents a spatial gap-filling framework using a univariate statistical method such as DCT-PLS (Discrete Cosine Transform-based Penalized Least Square Regression) and FMM (Fast Matching Method) inpainting. We conducted a feasibility test for the hourly AOD product from AHI (Advanced Himawari Imager) between January 1 and December 31, 2019, and compared the accuracy statistics of the two spatial gap-filling methods. When the null-pixel area is not very large (null-pixel ratio < 0.6), the validation statistics of DCT-PLS and FMM techniques showed high accuracy of CC=0.988 (MAE=0.020) and CC=0.980 (MAE=0.028), respectively. Together with the AI-based gap-filling method using extra explanatory variables, the DCT-PLS and FMM techniques can be tested for the low-resolution images from the AMI (Advanced Meteorological Imager) of GK2A (Geostationary Korea Multi-purpose Satellite 2A), GEMS (Geostationary Environment Monitoring Spectrometer) and GOCI2 (Geostationary Ocean Color Imager) of GK2B (Geostationary Korea Multi-purpose Satellite 2B) and the high-resolution images from the CAS500 (Compact Advanced Satellite) series soon.

• Journal of Environmental Science International
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• v.31 no.9
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• pp.743-755
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• 2022

This study aims to review the differences in urban regeneration independently implemented by the government (Ministry of Land, Infrastructure, and Transport, MOLIT) and Seoul based on related laws and ordinances, and to draw out the implications of Korean urban regeneration's directions. The results are as follows. First, Seoul has constantly responded to the revision of the Urban Regeneration Act by adjusting and specifying the contents of ordinances, and especially, there have been efforts to enhance regional characteristics suitably for the circumstances of Seoul. Second, in the urban regeneration of Seoul, the budgets including the matching ratio of national and local subsidies shall be changed according to the standards of the MOLIT in changing designating places after the selection of the urban regeneration by the ministry, and this procedure and these implementation methods cause confusion to Seoul and local governments. Third, there were differences in the results of comparing the budgets and support methods of the "Gaggum Housing Project" of Seoul and "New Deal Housing Repair Project" of the MOLIT, which caused conflicts due to the differences in the project implementation and support standards, and the arbitrary interpretation of the guidelines. Although the urban regeneration greatly contributed to the revelation and conservation of regional characteristics, it might be necessary to establish systems that can enhance citizens' awareness and compensate the efficient contents needed for each region in the future.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.775-784
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• 2023

Drone images are being used more and more actively in the fields of surveying and spatial information, and are rapidly replacing existing aerial and satellite images. The technology of quickly acquiring real-time data at low cost and processing it is now being applied to actual industries beyond research. However, there are also problems encountered as this progresses. When high-resolution spatial information is acquired using a general 2D flight plan for a terrain with sever undulations, problems arise due to the difference in resolution of the data. In particular, when a low-altitude high-resolution image is taken using a drone in a mountainous or steep terrain, there may be a problem in image matching due to a resolution difference caused by terrain undulations. This problem occurs because a drone acquires data while flying on a 2D plane at a fixed altitude, just like conventional aerial photography. In order to acquire high-quality 3D data using a drone, the scale difference for the shooting distance should be considered. In addition, in order to obtain facade images of large structures, it is necessary to take images in 3D space. In this study, in order to improve the disadvantages of the 2D flight method, a 3D flight plan was established for the study area, and it was confirmed that high-quality 3D spatial information could be obtained in this way.

• Journal of Korean Critical Care Nursing
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• v.16 no.3
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• pp.24-33
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• 2023

Purpose : This study aims to establish an optimal cut-off score on the Braden scale for the assessment of pressure injury to detect pressure injury risks among inpatients in a South Korean tertiary hospital. Methods : This retrospective study used electronic medical records, from January to December 2022. A total of 654 patients were included in the study. Of these, 218 inpatients with pressure injuries and 436 without pressure injuries were classified and analyzed using 1:2 Propensity Score Matching (PSM), and the generalized estimating equation was performed using SPSS Version 26 and the R Machlt package program. Results : The cut-off value on the Braden scale for distinguishing pressure injury was 17 points, and the AUC (area under the ROC curve) was 0.531 (0.484-0.579). The sensitivity was 56.6% (45.5-67.7%) and the specificity was 69.7% (66.0-73.4%). With 17 points, the Braden scale cut-off distinguished those who had pressure injuries from those who did not at the time of admission (p < .03). In the pressure injury group, the Braden score on the day of the pressure injury was 14, with significant results in all subcategories except the moisture category. Conclusion : Our findings revealed that a cut-off value of 17 was optimal for predicting the risk of pressure injuries among tertiary hospital inpatients. Future studies should evaluate the optimal cut-off values in different clinical environments. Additionally, it is necessary to conduct multicenter large sample studies to verify the effectiveness of a 17 value in PI risk assessments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.1
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• pp.103-107
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• 2024

This paper is a study on a triangle patch antenna using a rectangle slot and strip conductor. The length and spacing of the slot were adjusted to confirm the characteristics of the triangle patch antenna with rectangle slot, and the area and shape of the radiation patch were changed to triangle, rectangle, and hexagon for impedance matching. The HFSS simulator was used to check the antenna parameter characteristics, and the antenna size was 26 mm ×26 mm. In this proposed antenna, the simulation frequency range with VSWR of 2 or less was 5.27 to 6.24 GHz. The bandwidth was 970 MHz. The frequency range of the fabricated antenna was 5.24 to 6.38 GHz, and the bandwidth 1140 MHz. The maximum radiation gain is 5.01 dBi. It was confirmed that all radiation patterns had directional characteristics.

• Journal of Cadastre & Land InformatiX
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• v.45 no.2
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• pp.149-160
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• 2015

This paper suggests the MMAS(Map Matching using Additional Surveying) method to improve the cadastral discrepancy search algorithm that currently does not include corrections of mis-represented parcel data. The MMAS is a method to search for cadastral discrepancy after correcting mis-represented parcel data using nearby anchor points confirmed by surveys. The MMAS first transforms the coordinate system of the digital cadastral map by overlaying anchor points obtained in the field surveying process over the corresponding edges of buildings and facility points on the digital topographic map. Then, it searches for cadastral discrepancy by checking if the area differences exceed the tolerance limit. This method improves the current method for searching for cadastral discrepancy by performing the process after correcting extortion of the digital cadastral map. This helps to identify cadastral discrepancies that are not detectable within the distorted digital cadastral map. With our experiment, this method identified more discrepancies compared to the method without the correcting the distortion of the digital cadastral map. We believe this method will be able to help the national cadastral re-survey by identifying potential cadastral discrepancy more accurately.