• Journal of Korea Water Resources Association
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• v.46 no.5
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• pp.465-476
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• 2013

The outgoing longwave radiation (Rlu) for estimation of evapotranspiration is essential to understand energy balance of earth. However, the ground measurement based Rlu has a limitation that the observation can just stand for the exact site, not for an area. In this study, remote sensing technique is adopted to compensate the limitation of ground observation using the geostationary satellite. We calculated Rlu using Communication, Ocean and Meteorological Satellite (COMS). We validated Rlu from COMS with Cheongmicheon (CFK) and Sulmacheon (SMK) flux tower observations controlled by Hydrological Survey Center. The results showed that Rlu from COMS represented reasonable correlation with ground based measurement. Based on the results in this study, COMS will be able to be used for estimation of evapotranspiration.

• Journal of Korea Water Resources Association
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• v.32 no.2
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• pp.163-176
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• 1999

Hydrology-based topographical informations generated by GIS techniques could be changed according to the selection of base map, algorithm of extraction, and so on. The purpose of this paper is to investigate the variation of SCS CN extracted by GIS technique and to propose the effective strategy for applying GIS to the rainfall-runoff simulation in ungaged basin. For experimental implementation, GIS spatial data, such as reconnaissance soil map, detailed interpretative soil map, landuse planning map and remotely sensed data(Landsat TM), were collected and generated to calculate the amount of effective rainfall in Pyungchang river basin. In applying SCS Runoff Curve Number to the test basin, the hydrological attribute data were analyzed. In addition, the characteristics of runoff responses according to the selection of GIS spatial data for SCS CN were reviewed. This study shows the applicability of GIS techniques to runoff simulation in ungaged basin by comparing with the measured flood hydrograph. It has been found that the detained interpretative soil map and remote sensing data are appropriate for calculating of SCS CN.

• Journal of Korea Water Resources Association
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• v.39 no.4 s.165
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• pp.363-372
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• 2006

Many methods have been used to estimate evapotranspiration. However, there is little information about the evapotranspiration from river basins with complicated topographies and variable land use. Remote sensing technique is a probable means to estimate distribution of the evapotranspiration in connection with regional characteristics of vegetation and landuse. The evapotranspiration not only depends on meteorological circumstances but also on the condition of the vegetation. The latter effect can be expressed in terms of NDVI(Normalized Difference Vegetation Index) obtained by NOAA/AVHRR datasets. In this paper, a simple method to estimate evapotranspiration of the Keum river basin is proposed based on NDVI and temperature data.

• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.1
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• pp.1-8
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• 2004

It's a very meaningful experimental study to image restoration of ancient villages vanished at the real life spatial world. Focused on Cheung-Pyung Lake around where most part were flooded by the Chung-Ju large dam founded in early 1980s, we used remote sensing technique in this study in order to restore topographical features before the flood with 3 dimensional effects. It was gathered comparatively good satellite photos and remotely sensed digital images, then its made a new color image from these and the topographical map which had been made before filled water. This task was putting together two kinds of different timed images. And then, we generated DEM(digital elevation model) including the outskirts of that area as harmonizing current contour lines with the map. That could be a perfect 3D image of Cheung-Pyung around before when it had been flood by making perspective images from all directions, north, south, east and west, for showing there in three dimensions. Also, flying simulation we made for close visiting can bring us to experience their real space at that time.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.499-504
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• 2015

Decision making by farmers regarding irrigation is critical for crop production. Therefore, the precision irrigation technique is very important to improve crop quality and yield. Recently, much attention has been given to remote sensing of crop canopy temperature as a crop water-stress indicator, because it is a scientifically based and easily applicable method even at field scales. This study monitored a series of time-variant canopy temperature of cucumber under three different irrigation treatments: under-irrigation (control), optimal-irrigation, and over-irrigation. The difference between canopy temperature ($T_c$) and air temperature ($T_a$), $T_c-T_a$, was calculated as an indicator of cucumber water stress. Vapor pressure deficit (VPD) was evaluated to define water stress on the basis of the temperature difference between leaf and air. The values of $T_c-T_a$ was negatively related to VPD; further, cucumber growth in the under- and over-irrigated fields showed water stress, in contrast to that grown in the optimally irrigated field. Thus, thermal infrared measurements could be useful for evaluating crop water status and play an important role in irrigation scheduling of agricultural crops.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.6
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• pp.101-115
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• 2021

The purpose of this study is to evaluate the compatibility of the vegetation index between the two satellites and the applicability of agricultural monitoring by comparing and verifying NDVI (Normalized Difference Vegetation Index) based on Sentinel-2 and Terra MODIS (Moderate Resolution Imaging Spectroradiometer). Terra MODIS NDVI utilized 16-day MOD13Q1 data with 250 m spatial resolution, and Sentinel-2 NDVI utilized 10-day Level-2A BOA (Bottom Of Atmosphere) data with 10 m spatial resolution. To compare both NDVI, Sentinel-2 NDVIs were reproduced at 16-day intervals using the MVC (Maximum Value Composite) technique. As a result of time series NDVIs based on two satellites for 2019 and compare by land cover, the average R² (Coefficient of determination) and RMSE (Root Mean Square Error) of the entire land cover were 0.86 and 0.11, which indicates that Sentinel-2 NDVI and MODIS NDVI had a high correlation. MODIS NDVI is overestimated than Sentinel-2 NDVI for all land cover due to coarse spatial resolution. The high-resolution Sentinel-2 NDVI was found to reflect the characteristics of each land cover better than the MODIS NDVI because it has a higher discrimination ability for subdivided land cover and land cover with a small area range.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.4
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• pp.275-281
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• 2019

A synthetic aperture radar(SAR) satellite is more effective than an optical satellite for target analysis because an SAR satellite can provide two-dimensional electromagnetic scattering distribution of a target during all-weather and day-and-night operations. To conduct target analysis while considering the earth observation interval of an SAR satellite, observing a specific area as wide as possible would be advantageous. However, wider the observation area, worse is the resolution of the associated SAR satellite image. Although conventional methods for improving the resolution of radar images can be employed for addressing this issue, few studies have been conducted for improving the resolution of SAR satellite images and analyzing the performance. Hence, in this study, the applicability of conventional methods to SAR satellite images is investigated. SAR target detection was first applied to Korea Multipurpose Satellite-5(KOMPSAT-5) SAR images provided by Korea Aerospace Research Institute for extracting target responses. Extrapolation, RELAX, and MUSIC algorithms were subsequently applied to the target responses for improving the resolution, and the corresponding performance was thereby analyzed.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1081-1088
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• 2020

In this paper, the method of detecting sea fog through CCTV image is proposed based on convolutional neural networks. The study data randomly extracted 1,0004 images, sea-fog and not sea-fog, from a total of 11 ports or beaches (Busan Port, Busan New Port, Pyeongtaek Port, Incheon Port, Gunsan Port, Daesan Port, Mokpo Port, Yeosu Gwangyang Port, Ulsan Port, Pohang Port, and Haeundae Beach) based on 1km of visibility. 80% of the total 1,0004 datasets were extracted and used for learning the convolutional neural network model. The model has 16 convolutional layers and 3 fully connected layers, and a convolutional neural network that performs Softmax classification in the last fully connected layer is used. Model accuracy evaluation was performed using the remaining 20%, and the accuracy evaluation result showed a classification accuracy of about 96%.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.55-55
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• 2023

물 인프라 시설물은 다양한 산업 및 지역 사회에 필요한 물 공급과 이와 관련된 인프라를 제공하는 현대 사회의 중요한 구성 요소 중 하나이다. 이러한 시설이 노후화 되면서 안전과 신뢰성에 대한 우려가 커지면서 과거 건설, 개발 중심에서 유지, 관리 중심으로 패러다임이 변화하고 있다. 이에 물 인프라 시설물의 상태를 정밀하게 조사하고, 정확한 계측하는 기술에 대한 수요가 지속적으로 증가하고 있다. 최근, 드론에 초분광 센서를 탑재하여 초분광 영상을 수집할 수 있는 기술이 개발되고 있으며, 물 인프라 시설물에 대한 원격탐사 및 모니터링이 이러한 수요를 만족시킬 수 있는 유망한 해결책으로 부상하고 있다. 특히, 이러한 초분광 영상 수집 기술을 이용하면 물 인프라 시설물 주변의수심, 수질, 온도 등 환경적 요인 뿐만 아니라 재료에 따른 상태를 파악할 수 있어, 잠재적으로 구조 결함을 감지하는데 필요한 상세한 분광 정보를 수집할 수 있다. 또한, "저수지·댐의 안전관리 및 재해예방에 관한 법률"에서 정기적인 정밀안전진단을 요구하고 있으며, "중대재해처벌법"에 따라 인력중심의 조사, 계측 방식의 어려움이 있는 상황에서 드론 기반의 초분광 원격탐사 기술은 매력적인 선택지이다. 본 연구는 안전과 신뢰성에 대한 우려가 커지고 있는 물 인프라 시설물에서 드론 기반 초분광영상 기술이 제공하는 새로운 해결책에 대한 연구로, "저수지·댐 안전관리 및 재해예방에 관한 법률"에서 제시하는 물 인프라 시설의 정기적인 검사 및 유지보수에 대한 중요성을 더욱 강조하는 것으로, 물 인프라 시설물을 정확하게 모니터링하고 조사, 계측하는 능력의 중요성을 증가시킬 수 있는 기술이다. 따라서 본 연구에서는 드론 기반의 초분광 영상 수집 기술을 활용하여 물 인프라시설물의 원격탐사 및 모니터링에 대한 적용성을 검토하고자 한다. 이를 통해 드론 기반 초분광영상 기술이 물 인프라 시설물의 조사 및 계측, 유지 보수에 대한 새로운 해결책이 될 수 있는지 검토한다. 또한 이 기술의 잠재적인 이점과 한계를 탐구하고, 정확하고 신뢰성 높은 계측, 조사 기술에 대한 증가하는 수요를 충족시키기 위한 능력을 평가 하고자 한다.

• Korean Journal of Materials Research
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• v.33 no.9
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• pp.360-366
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• 2023

This study focuses on how the partial substitution of copper by nickel nanoparticles affects the electrical and structural properties of the Bi₂Ba₂Ca₂Cu_2.9Ni_0.1O_10+δ, Bi₂Ba₂Ca₂Cu_2.8Ni_0.2O_10+δ and Bi₂Ba₂Ca₂Cu_2.6Ni_0.4O_10+δ compounds. Approximate values of crystallization size and crystallization percentage for the three compounds were calculated using the Scherer, modified Scherer, and Williamson-Hall methods. A great similarity was observed in the crystal size values from the Scherer method, 243.442 nm, and the Williamson-Hall method, 243.794 nm for the second sample. At the same time this sample exhibited the highest crystal size value for the three methods. In the examination of electrical properties, the sample with 0.1 partial substitution, Bi₂Ba₂Ca₂Cu_2.9Ni_0.1O_10+δ was determined to be the best with a critical temperature of 100 K and an energy gap of 6.57639 × 10^-21 MeV. Using the SEM technique to analyze the structural morphology of the three phases, it was discovered that the size of the granular forms exceeds 25 nm. It was determined that the samples' shapes alter when nickel concentration rises. The patterns that reveal the distribution of the crystal structure also exhibit clear homogeneity.