• Korean Journal of Remote Sensing
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• v.38 no.6_3
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• pp.1777-1788
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• 2022

The reservoir is a major water supply source in the domestic agricultural environment, and the monitoring of water storage of reservoirs is important for the utilization and management of agricultural water resource. Remote sensing via satellite imagery can be an effective method for regular monitoring of widely distributed objects such as reservoirs, and in this study, image classification and image segmentation algorithms are applied to Sentinel-1 Synthetic Aperture Radar (SAR) imagery for water body detection in 53 reservoirs in South Korea. Six algorithms are used: Neural Network (NN), Support Vector Machine (SVM), Random Forest (RF), Otsu, Watershed (WS), and Chan-Vese (CV), and the results of water body detection are evaluated with in-situ images taken by drones. The correlations between the in-situ water surface area and detected water surface area from each algorithm are NN 0.9941, SVM 0.9942, RF 0.9940, Otsu 0.9922, WS 0.9709, and CV 0.9736, and the larger the scale of reservoir, the higher the linear correlation was. WS showed low recall due to the undetected water bodies, and NN, SVM, and RF showed low precision due to over-detection. For water body detection through SAR imagery, we found that aquatic plants and artificial structures can be the error factors causing undetection of water body.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.376-386
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• 2023

Due to climate changes, landslide hazards in the Republic of Korea (hereafter South Korea) continuously increase. To establish the effective landslide mitigation strategies, such as erosion control works, landslide hazard estimation in the long-term perspective should be proceeded considering the influence of climate changes. In this study, we examined the change in landslide-damaged areas in South Korea responding to climate change scenarios using the multivariate regression method. Data on landslide-damaged areas and rainfall from 1981-2010 were used as a training dataset. Sev en indices were deriv ed from rainfall data as the model's input data, corresponding to rainfall indices provided from two SSP scenarios for South Korea: SSP1-2.6 and SSP5-8.5. Prior to the multivariate regression analysis, we conducted the VIF test and the dimension analysis of regression model using PCA. Based on the result of PCA, we developed a regression model for landslide damaged area estimation with two principal components, which cov ered about 93% of total v ariance. With climate change scenarios, we simulated landslide-damaged areas in 2030-2100 using the regression model. As a result, the landslide-damaged area will be enlarged more than the double of current annual mean landslide damaged area of 1981-2010; It infers that landslide mitigation strategies should be reinforced considering the future climate condition.

• Korean Journal of Remote Sensing
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• v.31 no.6
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• pp.501-512
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• 2015

Landfast sea ice (LFI) in Terra Nova Bay, East Antarctica where the Jangbogo Antarctic Research Station is located, has significant influences on marine ecosystem and the sailing of an icebreaker. Therefore, it is essential to analyze the spatio-temporal variation of the LFI in Terra Nova Bay. In this study, we chose interferometric pairs with the temporal baseline from 1 to 9 days out of a total of 62 COSMO-SkyMed synthetic aperture radar (SAR) images over Terra Nova Bay obtained from December 2010 to January 2012, and then constructed the coherence image of each pair. The LFI showed coherence values higher than 0.3 even in the interferometric SAR (InSAR) pairs of up to 9-days of temporal baseline. This was because the LFI was fixed at coastline and thus showed low temporal phase decorrelation. Based on the characteristics of the coherence on LFI, We defined the areas of LFI that show spatially homogeneous coherence values higher than 0.5. Pack ice (PI) and open water showed low coherence values due to large temporal phase decorreation caused by current and wind. Distinguishing PI from open water in the coherence images was difficult due to their similarly low coherence values. PI was identified in SAR amplitude images by investigating cracks on the ice. The extents of the LFI and PI were estimated from the coherence and SAR amplitude images and their temporal variations were analyzed. The extent of the LFI increased from March to July (maximum extent of $170.7km^2$) and decreased from October. The extent of the PI increased from February to May and decreased from May to July when the LFI increases dramatically. The extent of the LFI and air temperature showed an inverse correlation with a time lag of about 2 months, i.e., the extent of the LFI decreases after 2 months of the increase in the air temperature. Meanwhile the correlation between wind speed and the extent of the LFI was very low. This represents that the extent of LFI in Terra Nova Bay are influenced more by the air temperature than wind speed.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.266-271
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• 2012

This study was carried out to evaluate the land suitability for southern-type garlic cultivation associated with both temperature and soil constraints. The suitability analysis was conducted with hourly temperature data from 2001 to 2010 at all fifty seven meteorological stations and the soil-based suitability map of garlic provided by Rural Development Administration. Firstly the temperature data were processed by the growth stages (germinating, bulbing, and winter vegetation season), and then were adopted to limit the irrelevant lands. Next, as a result of overlaying each soil and temperature suitability map, the total 274,339 ha of area was mapped as highly suitable or suitable for southern-type garlic cultivation and the top four of the largest classified si-guns were identified as Naju, Jeongeup, Gochang, and Jinju. On the other hand, the statistical records of KOSIS (KOrea Statistical Information Service) showed lower amount of cultivation area than the analyzed results in the major production sites, Goheung, Sinan, Haenam, and Muan. However, it should not be regarded as exceptional because farmer's preference might not correspond to potential land usability.

• Journal of Korea Water Resources Association
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• v.53 no.7
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• pp.545-555
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• 2020

A feasibility modeling for potential hydroelectric dam site selection was suggested using 1 sec ASTGTM (ASTER Global Digital Elevation Model) and Terra/Aqua MODIS (Moderate Resolution Imaging Spectroradiometer) derived land use (MCD12Q1) data. The modeling includes DEM pre-processing of peak, sink, and flat, river network generation, watershed delineation and segmentation, terrain analysis of stream cross section and reservoir storage, and estimation of submerged area for compensation. The modeling algorithms were developed using Python and as an open source GIS. When a user-defined stream point is selected, the model evaluates potential hydroelectric head, reservoir surface area and storage capacity curve, watershed time of concentration from DEM, and compensation area from land use data. The model was tested for 4 locations of already constructed Buhang, BohyunMountain, Sungdeok, and Yeongju dams. The modeling results obtained maximum possible heads of 37.0, 67.0, 73.0, 42.0 m, surface areas of 1.81, 2.4, 2.8, 8.8 ㎢, storages of 35.9, 68.0, 91.3, 168.3×10⁶ ㎥ respectively. BohyunMountain and Sungdeok show validity but in case of Buhang and Yeongju dams have maximum head errors. These errors came from the stream generation error due to ASTGTM. So, wrong dam watershed boundary limit the head. This study showed a possibility to estimate potential hydroelectric dam sites before field investigation especially for overseas project.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.2
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• pp.38-43
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• 2001

In this study, the technique of the performance prediction on the finocyl-type dual-thrust rocket motor is developed, and the predicted data are compared with those of the static firing tests. The prediction is carried out with the separate calculations of the grain burning area and the performance of the rocket motor. When predicting the performance of the dual-thrust rocket motor, the different correction factors should be used at the boosting and sustaining phases. Otherwise, an error of prediction will follow. Reprediction using the separate correction factors shows good agreement with the test data within 0.5% error.

• 한국공간정보시스템학회:학술대회논문집
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• 2005.05a
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• pp.249-253
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• 2005

인공위성 데이터를 이용한 원격탐사 기술과 지형공간정보시스템의 통합에 의한 도시에의 활용은 도시 계획뿐 만 아니라, 환경정비와 유지 관리 측면 등에서 중요한 역할을 하고 있다. 본 연구는 대상지역의 Landsat TM 영상자료를 이용하여 보정과정을 수행하고, GSIS 시스템의 NDVI(Normalized Difference Vegetation Index)식을 이용하여 식생지수를 추출하였다. 산출된 식생지수를 5개 등급으로 분류하여 비 식생지역과 식생이 활발한 지역을 구분하여 분석하였고, 인공위성 데이터의 밴드간 비연산 처리를 실시하여 식물의 건강상태를 나타내는 NDVI를 위성 데이터를 이용하여 추출함으로써, 시가지내의 녹지분포에 대한 시계열적 변화를 분석하였다. 이 결과 도심주변지역에 분포하는 낯은 구릉지에서 점차적으로 도시화가 이루어짐을 알 수 있었고, 전체 면적별 녹지분포가 높은 구릉지 및 산악지역의 3, 4, 5등급지역 면적 비율이 68.9%에서 37.2%로 감소한 것으로 나타났다.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2001.11a
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• pp.201-202
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• 2001

옵셋인쇄에서 종이로부터 나오는 이물질에 의한 인새 트러블은 자주발생되는 현상이다. 인쇄물 상에서 나타나는 이러한 현상은 주로 회색 반점이나 히키(Hickey, Catyes) 혹은 Blanket poling으로 나타난다. 원인에 따라 Dust, Linting, Picking, Delamination, Piling으로 나눌 수 있다. 인쇄에서 이물질의 발생에 영향을 주는 요소가 많고 일반적인 경우에는 복합적인 원인에 의한 경우가 많아 인쇄물만으로는 이물질의 종류나 발생 원인을 파악하기 어렵다. 본 연구는 자체 제작한 Test chart를 이용하여 실인쇄 실험을 함으로써 이물질의 종류와 발생 원인을 분석한 사레를 보고하고자 한다. Test chart의 구성은 동일 면적의 화선면적율 20, 50, 75, 100%를 갖도록 설계하였고, 인쇄중 잉크(1st oscillating roll). 습수통(Dampening founation solution), Blanket 표면온도를 측정하였으며, 일정 부수 인쇄 후 인쇄판, Blanket, 인쇄물을 회수하여 분석하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.737-742
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• 2005

본 연구는 GIUH(Geomorphologic Instantaneous Unit Hydrograph) 매개변수와 유역의 지 형특성 인자인 유역면적, 유로연장, 유로경사의 상관성을 분석하여 유역면적과 유로연장의 GIUH 매개변수와의 상관식을 유도하였다. 그리고 대상유역의 Fractal분석도 실시하여 지형상사를 확인하였다. 상관식의 검증을 위해 설마천 유역을 선정하여 결과를 실측치를 계산치와 수정치로 비교하고 계산치와 수정치도 비교하였다. 본 연구의 결과로 산정된 상관식을 사용하여 임의의 미계측 유역의 GIUH매개변수를 산정할 경우 기존의 복잡하고 시간이 많이 소요되는 GIS작업의 번거로움을 최소화할 수 있을 것이다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.299-301
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• 2012

제주 강정항은 우리나라 남방해역의 보호라는 안보적인 측면과 대형 크루즈선 유치를 통한 관광산업의 활성화를 위해 해군기지와 민항의 기능을 가진 민 군복항으로 건설되고 있다. 본 연구에서는 제주 강정항 계류시설의 대상선박인 15만톤급 초대형 크루즈선의 입 출항 및 통항 안전성 판별을 위해 실시하는 선박조종시뮬레이션의 일반 수행 절차와 선행 연구 등을 분석한다. 이는 선행 연구에서 제기된 주요 쟁점사항들을 명확하게 분석함으로써 객관적이고 신뢰성 높은 선박조종시뮬레이션 연구를 수행하고자 하는 것으로, 주요 검토 사항은 수역시설인 선회장과 진입항로의 교각, 크루즈선의 풍압면적과 적용 풍속 등을 면밀하게 고찰하여 시뮬레이션에 반영하고자 함이다. 또한 제주 강정한 건설은 사회적 관심이 매우 큰 국책사업임을 감안하여 선박조종시뮬레이션 분석 및 평가 등에 해상교통안전 및 선박운용 분야의 전문가그룹을 자문위원으로 구성했고, 연구 결과의 타당성 확보를 위해 해상교통안전진단제도에 명시된 선박조종시뮬레이션 표준절차와 평가 방법 등을 적용하였다.