• Korean Journal of Remote Sensing
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• v.36 no.2_2
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• pp.249-261
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• 2020

Coastal monitoring using multiple platforms/sensors is a very important tools for accurately understanding the changes in offshore marine environment and disaster with high temporal and spatial resolutions. However, integrated observation studies using multiple platforms and sensors are insufficient, and none of them have been evaluated for efficiency and limitation of convergence. In this study, we aimed to suggest an integrated observation method with multi-remote sensing platform and sensors, and to diagnose the utility and limitation. Integrated in situ surveys were conducted using Rhodamine WT fluorescent dye to simulate various marine disasters. In September 2019, the distribution and movement of RWT dye patches were detected using satellite (Kompsat-2/3/3A, Landsat-8 OLI, Sentinel-3 OLCI and GOCI), unmanned aircraft (Mavic 2 pro and Inspire 2), and manned aircraft platforms after injecting fluorescent dye into the waters of the South Sea-Yeosu Sea. The initial patch size of the RWT dye was 2,600 ㎡ and spread to 62,000 ㎡ about 138 minutes later. The RWT patches gradually moved southwestward from the point where they were first released,similar to the pattern of tidal current flowing southwest as the tides gradually decreased. Unmanned Aerial Vehicles (UAVs) image showed highest resolution in terms of spatial and time resolution, but the coverage area was the narrowest. In the case of satellite images, the coverage area was wide, but there were some limitations compared to other platforms in terms of operability due to the long cycle of revisiting. For Sentinel-3 OLCI and GOCI, the spectral resolution and signal-to-noise ratio (SNR) were the highest, but small fluorescent dye detection was limited in terms of spatial resolution. In the case of hyperspectral sensor mounted on manned aircraft, the spectral resolution was the highest, but this was also somewhat limited in terms of operability. From this simulation approach, multi-platform integrated observation was able to confirm that time,space and spectral resolution could be significantly improved. In the future, if this study results are linked to coastal numerical models, it will be possible to predict the transport and diffusion of contaminants, and it is expected that it can contribute to improving model accuracy by using them as input and verification data of the numerical models.

• Korean Journal of Remote Sensing
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• v.35 no.1
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• pp.57-81
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• 2019

Satellite images can be integrated into a crop model to strengthen the advantages of each technique for crop monitoring and to compensate for weaknesses of each other, which can be systematically applied for monitoring inaccessible croplands. The objective of this study was to outline the productivity of paddy rice based on simulation of the yield of all paddy fields in North Korea, using a grid crop model combined with optical satellite imagery. The grid GRAMI-rice model was used to simulate paddy rice yields for inaccessible North Korea based on the bidirectional reflectance distribution function-adjusted vegetation indices (VIs) and the solar insolation. VIs and solar insolation for the model simulation were obtained from the Geostationary Ocean Color Imager (GOCI) and the Meteorological Imager (MI) sensors of the Communication Ocean and Meteorological Satellite (COMS). Reanalysis data of air temperature were achieved from the Korea Local Analysis and Prediction System (KLAPS). Study results showed that the yields of paddy rice were reproduced with a statistically significant range of accuracy. The regional characteristics of crops for all of the sites in North Korea were successfully defined into four clusters through a spatial analysis using the K-means clustering approach. The current study has demonstrated the potential effectiveness of characterization of crop productivity based on incorporation of a crop model with satellite images, which is a proven consistent technique for monitoring of crop productivity in inaccessible regions.

• Korean Journal of Optics and Photonics
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• v.22 no.3
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• pp.151-158
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• 2011

This paper reports design and demonstration of optical systems for reflective-type remote optical displacement sensors. Optical systems for light illumination sources and a position sensitive detector (PSD) for the displacement sensor were developed to sense displacement of bridges and instability of skyscrapers in a distance range from 10 m to 250 m to an accuracy better than a few mm. Performance of the optical systems was verified by composing a displacement sensor and by using it in measurement of displacement of a remote target with proper reflective optics depending on distance. The displacement sensor was composed of two LED light sources, each with collimating optics, and a two-dimensional PSD with telescope-type optics. Its displacement resolutions was measured to be 0.1 mm at a distance of 10 m and less than 3 mm at a distance of 250 m.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.337-340
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• 2005

Context-awareness techniques in ubiquitous computing environment provide various services to users who need to get information via the analysis of collected information from sensors in a spatial area. Context-awareness has been increased in ubiquitous computing and is applied to many different applications such as disaster management system, intelligent robot system, transportation management system, shopping management system, and digital home service. Many researches have recently focused on services that provide the appropriate information, which are collected from Internet by different kinds of sensors, to users according to context of their surrounding environment. In this paper, we propose an abstraction model to manage the large-scale contextual information and their metadata which are collected from different kinds of in-situ sensors in a spatial area and are presented them on the web. This model is composed of the modules expressing functional elements of sensors using sensorML(Sensor Model Language) based on XML language and the modules managing contextual information, which is transmitted from the sensors.

• Journal of the Korea Society of Computer and Information
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• v.12 no.3
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• pp.155-163
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• 2007

In this paper, Though sensors of Ubiquitous Middle-ware System based on RFID/USN can usually be reacted from six mouths to two years, they can be exhausted their power of storage battery only one day by communication rates and ranges. That is, the lifetime of sensor node is depended on how much spending power under wireless communication that can communicate its sensing data to its destination. Therefore, it is necessary that each sensor should be designed the Routing path to its destination, in order to remote collecting data. But, in order to improve lifetime of sensor node and modify inner setting, it is opposite to simple searching path method of sensor node by entering external commands. accordingly, 1:n sensor arrangement of n form command and data send-receive that is possible simulation do without interference other sensors and research to different sensor data analysis and conversion ways to convert Sensing data that accept from sensors to actuality information.

• Proceedings of the KSRS Conference
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• v.2
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• pp.852-855
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• 2006

There is an increasing need to use data from different sensors in order to maximize the chances of obtaining a cloud-free image and to meet timely requirements for information. However, the use of data from multiple sensor systems is depending on comprehensive relationships between sensors of different types. Indeed, a study of inter-sensor relationships is well advanced in the effective use of remotely sensed data from multiple sensors. This paper was concerned with relationships between sensors of different types for vegetation indices (VI). The study was conducted using IKONOS and Landsat-7 ETM+ images. IKONOS and Landsat-7 ETM+ image of the same or about the same dates were acquired. The Landsat-7 ETM+ images were resampled in order to make them coincide with the pixel sizes of IKONOS. Inter-relationships of vegetation indices between images were performed using at-satellite reflectance obtained by converting image digital number (DN). All images were applied to topographic normalization method in order to reduce topographic effect in digital imagery. Also, Inter-sensor model equations between two sensors were developed and applied to other study region. In the result, the relational equations can be used to compute or interpret VI of one sensor using the VI of another sensor.

• Korean Journal of Remote Sensing
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• v.29 no.3
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• pp.275-291
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• 2013

Monitoring the global Gross Primary Pproduction (GPP) is relevant to understanding the global carbon cycle and evaluating the effects of interannual climate variation on food and fiber production. GPP, the flux of carbon into ecosystems via photosynthetic assimilation, is an important variable in the global carbon cycle and a key process in land surface-atmosphere interactions. The Moderate-resolution Imaging Spectroradiometer (MODIS) is one of the primary global monitoring sensors. MODIS GPP has some of the problems that have been proven in several studies. Therefore this study was to solve the regional mismatch that occurs when using the MODIS GPP global product over Korea. To solve this problem, we estimated each of the GPP component variables separately to improve the GPP estimates. We compared our GPP estimates with validation GPP data to assess their accuracy. For all sites, the correlation was close with high significance ($R^2=0.8164$, $RMSE=0.6126g{\cdot}C{\cdot}m^{-2}{\cdot}d^{-1}$, $bias=-0.0271g{\cdot}C{\cdot}m^{-2}{\cdot}d^{-1}$). We also compared our results to those of other models. The component variables tended to be either over- or under-estimated when compared to those in other studies over the Korean peninsula, although the estimated GPP was better. The results of this study will likely improve carbon cycle modeling by capturing finer patterns with an integrated method of remote sensing.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.3
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• pp.211-218
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• 2015

The analysis of remote sensing data depends on sensor specifications that provide accurate and consistent measurements. However, it is not easy to establish confidence and consistency in data that are analyzed by different sensors using various radiometric scales. For this reason, the cross-calibration method is used to calibrate remote sensing data with reference image data. In this study, we used an airborne hyperspectral image in order to calibrate a multispectral image. We presented an automatic cross-calibration method to calibrate a multispectral image using hyperspectral data and spectral mixture analysis. The spectral characteristics of the multispectral image were adjusted by linear regression analysis. Optimal endmember sets between two images were estimated by spectral mixture analysis for the linear regression analysis, and bands of hyperspectral image were aggregated based on the spectral response function of the two images. The results were evaluated by comparing the Root Mean Square Error (RMSE), the Spectral Angle Mapper (SAM), and average percentage differences. The results of this study showed that the proposed method corrected the spectral information in the multispectral data by using hyperspectral data, and its performance was similar to the manual cross-calibration. The proposed method demonstrated the possibility of automatic cross-calibration based on spectral mixture analysis.

• Korean Journal of Remote Sensing
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• v.33 no.4
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• pp.377-390
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• 2017

Space-based Synthetic Aperture Radar (SAR) observations have been widely and successfully applied to acquire invaluable temporal and spatial information on wetlands, which are unique environments and regarded as important ecosystems. One of the best studied wetland area is Everglades, which is located in southern Florida, USA. As a World Heritage Site, the Everglades is the largest natural and subtropical wilderness in the United States. The Everglades wetlands have been threatened by anthropogenic activities such as urban expansion and agricultural development, as well as by natural processes, as sea level changes due to climate change. In order to conserve this unique wetland environment, various restoration plans have been implemented. In this review paper, we summarize the main studies using space-based SAR observations for monitoring the Everglades. The paper is composed of the following two sections: (1) review of backscattered amplitude analysis and observations, and (2) review of interferometric SAR (InSAR) analysis and applications. This study also provides an overview of a wetland InSAR technique and space-based SAR sensors. The goal of this review paper is to provide a comprehensive summary of space-based SAR monitoring of wetlands, using the Everglades wetlands as a case study.

• Korean Journal of Remote Sensing
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• v.33 no.4
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• pp.411-422
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• 2017

This research aims to analyze spectral reflectance of intertidal zone and its changes under various environmental conditions. We sampled sand of Mongsanpo tidal flat, Korea, and measured its spectral reflectance by using a spectroradiometer under various water contents, compositions and granularity. We also simulated the reflectance of Landsat 7 ETM+ and compared it with an actual satellite data. Five locations were selected for sampling from the coastline towards the ocean. Grain size diminished stepwise from the coastline to ocean direction, while spectral reflectance differed with wavelength. Water contents lowered the overall reflectance especially at the water absorption bands. Spectral reflectance data were then converted into the simulated one by using Landsat 7 ETM+ spectral reflectance function to be compared with the actual Landsat 7 ETM+ images. It showed the decrease of the spectral reflectance due to the increase of moisture contents from seashore towards the ocean. It is shown that Landsat 7 ETM+ imagery can be efficient to extract moisture contents in the tidal flat while compositional analysis needs satellite sensors with much higher spectral resolution.