• Korean Journal of Remote Sensing
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• v.37 no.5_2
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• pp.1329-1340
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• 2021

The intertidal zone, which is a transitional zone between the ocean and the land, requires continuous monitoring as various changes occur rapidly due to artificial activity and natural disturbance. Monitoring of coastal topography changes using remote sensing method is evaluated to be effective in overcoming the limitations of intertidal zone accessibility and observing long-term topographic changes in intertidal zone. Most of the existing coastal topographic monitoring studies using remote sensing were conducted through high spatial resolution images such as Landsat and Sentinel. This study extracted the waterline using the NDWI from the GOCI-II (Geostationary Ocean Color Satellite-II) data, identified the changes in the intertidal area in Gyeonggi Bay according to various tidal heights, and examined the utility of DEM generation and topography altitude change observation over a short period of time. GOCI-II (249 scenes), Sentinel-2A/B (39 scenes), Landsat 8 OLI (7 scenes) images were obtained around Gyeonggi Bay from October 8, 2020 to August 16, 2021. If generating intertidal area DEM, Sentinel and Landsat images required at least 3 months to 1 year of data collection, but the GOCI-II satellite was able to generate intertidal area DEM in Gyeonggi Bay using only one day of data according to tidal heights, and the topography altitude was also observed through exposure frequency. When observing coastal topography changes using the GOCI-II satellite, it would be a good idea to detect topography changes early through a short cycle and to accurately interpolate and utilize insufficient spatial resolutions using multi-remote sensing data of high resolution. Based on the above results, it is expected that it will be possible to quickly provide information necessary for the latest topographic map and coastal management of the Korean Peninsula by expanding the research area and developing technologies that can be automatically analyzed and detected.

• Journal of the Korean Geotechnical Society
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• v.38 no.7
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• pp.5-24
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• 2022

The current performance evaluation of slope anchors qualitatively determines the physical bonding between the anchor head and ground as well as cracks or breakage of the anchor head. However, such performance evaluation does not measure these primary factors quantitatively. Therefore, the time-dependent management of the anchors is almost impossible. This study is an evaluation of the 3D numerical model by SfM which combines UAS images with terrestrial LiDAR to collect numerical data on the damage factors. It also utilizes the data for the quantitative maintenance of the anchor system once it is installed on slopes. The UAS 3D model, which often shows relatively low precision in the z-coordinate for vertical objects such as slopes, is combined with terrestrial LiDAR scan data to improve the accuracy of the z-coordinate measurement. After validating the system, a field test is conducted with ten anchors installed on a slope with arbitrarily damaged heads. The damages (such as cracks, breakages, and rotational displacements) are detected and numerically evaluated through the orthogonal projection of the measurement system. The results show that the introduced system at the resolution of 8K can detect cracks less than 0.3 mm in any aperture with an error range of 0.05 mm. Also, the system can successfully detect the volume of the damaged part, showing that the maximum damage area of the anchor head was within 3% of the original design guideline. Originally, the ground adhesion to the anchor head, where the z-coordinate is highly relevant, was almost impossible to measure with the UAS 3D numerical model alone because of its blind spots. However, by applying the combined system, elevation differences between the anchor bottom and the irregular ground surface was identified so that the average value at 20 various locations was calculated for the ground adhesion. Additionally, rotation angle and displacement of the anchor head less than 1" were detected. From the observations, the validity of the 3D numerical model can obtain quantitative data on anchor damage. Such data collection can potentially create a database that could be used as a fundamental resource for quantitative anchor damage evaluation in the future.

• Korean Journal of Remote Sensing
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• v.39 no.6_1
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• pp.1211-1224
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• 2023

Clouds cause many difficult problems in observing land surface phenomena using optical satellites, such as national land observation, disaster response, and change detection. In addition, the presence of clouds affects not only the image processing stage but also the final data quality, so it is necessary to identify and remove them. Therefore, in this study, we developed a new cloud detection technique that automatically performs a series of processes to search and extract the pixels closest to the spectral pattern of clouds in satellite images, select the optimal threshold, and produce a cloud mask based on the threshold. The cloud detection technique largely consists of three steps. In the first step, the process of converting the Digital Number (DN) unit image into top-of-atmosphere reflectance units was performed. In the second step, preprocessing such as Hue-Value-Saturation (HSV) transformation, triangle thresholding, and maximum likelihood classification was applied using the top of the atmosphere reflectance image, and the threshold for generating the initial cloud mask was determined for each image. In the third post-processing step, the noise included in the initial cloud mask created was removed and the cloud boundaries and interior were improved. As experimental data for cloud detection, CAS500-1 L2G images acquired in the Korean Peninsula from April to November, which show the diversity of spatial and seasonal distribution of clouds, were used. To verify the performance of the proposed method, the results generated by a simple thresholding method were compared. As a result of the experiment, compared to the existing method, the proposed method was able to detect clouds more accurately by considering the radiometric characteristics of each image through the preprocessing process. In addition, the results showed that the influence of bright objects (panel roofs, concrete roads, sand, etc.) other than cloud objects was minimized. The proposed method showed more than 30% improved results(F1-score) compared to the existing method but showed limitations in certain images containing snow.

• Journal of Preventive Medicine and Public Health
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• v.26 no.1 s.41
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• pp.1-19
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• 1993

Mail questionnaire was administrated to 370 practising physicians and 388 pharmacists in Taegu city selected by systematic sampling to examine utilization states and opinion of pharmacy under medical care insurance programme and the attitude to the functional division between physicians and pharmacists from April to May 1992. Regarding the opinion on the outcome of drug-store under medical insurance, 71.2 percent of practicing physician answered faliure but 13.4 percent of practicing pharmacists answered failure in contrast. Fifty percent of practicing physician asserted introducing functional division between physician and pharmacist while 66.9 percent of practicing pharmacist answered drug-store under medical insurance itself is sucessful programme. Average daily numbers of preparation of medicine was 32.2 case. Percentage of utilization of drug-store under medical issurance to average daily cases of preparing of medicine was 20 percent, percentage of utilization with physician's prescription was 0.7 percent. And 58.7 percent of practicing physician experienced outside the institute prescription. Regarding the opinion on the pros and cons of enforcing functional division between physician and pharmacist, 59.2 percent of practicing physician prefered pros and 17.7 percent cons, but 38 percent of practicing pharmacist prefered pros and 45.5 percent cons. And pharmacist knew better the content of functional division between physician and pharmacist than physician. As a reason for pros of enforcing functional division between physician and pharmacist, practicing physician emphasized to prevent misuse or abuse of medicine but practicing pharmacist emphasized to display physician and pharmacist's professional ability. And as an opinion on implementation style of functional division between physician and pharmacist in pros respondents, practicing physician favored mandatory enforcement (52.3%), while practicing pharmacist favored partial incomplete functional division (81.7%). As the method of prescription if functional division between physician and pharmacist will be enforced, both practicing physician and pharmacist prefered generic name (44.0%, 89%) mostly, but physician prefered brand name (35.3%) secondly. Regarding the reason for not implementing functional division between physician and pharmacist up to date, both physician and pharmacist answered problem of business right between physician and pharmacist, followed by lack of recognition, and interest of people and lack of the govermental willness. Regarding the opinion on prior decision of condition for enforcing functional division between physician and pharmacist, practicing physician and pharmacist named uneven distribution of medical facilities and drug-store between rural and urban, inequality of physician and pharmacist manpower and the problem of manpower demand and supply mostly, and practicing physician pointed out establishing attitude of acceptance on the part of pharmacist and practicing pharmacist favored establishing attitude of acceptance on the part of physician, which was different attitudes between physician and pharmacist. Following conclusion was reached ; 1. Current drug-store under medical insurance program yield insufficient outcome, so we should consider program conversion from drug-store under medical insurance program to functional division between physician and pharmacist. 2. There were problem of business right and conflicts between physician and pharmacist at enforcing functional division between physician and pharmacist, so the goverment should search for formulating plan to resolve the problem and have neutral willness for the protection of the national health.