• Korean Journal of Remote Sensing
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• v.32 no.3
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• pp.235-244
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• 2016

In large-area crop classification with MODIS data, a mixed pixel problem caused by the low resolution of MODIS data has been one of main issues. To mitigate this problem, this paper proposes a hierarchical classification algorithm that selectively classifies the specific crop class of interest by using their spectral characteristics. This selective classification algorithm can reduce mixed pixel effects between crops and improve classification performance. The methodological developments are illustrated via a case study in Jilin city, China with MODIS Normalized Difference Vegetation Index (NDVI) and Near InfRared (NIR) reflectance datasets. First, paddy fields were extracted from unsupervised classification of NIR reflectance. Non-paddy areas were then classified into corn and bean using time-series NDVI datasets. In the case study result, the proposed classification algorithm showed the best classification performance by selectively classifying crops having similar spectral characteristics, compared with traditional direct supervised classification of time-series NDVI and NIR datasets. Thus, it is expected that the proposed selective hierarchical classification algorithm would be effectively used for producing reliable crop maps.

• Korean Journal of Remote Sensing
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• v.29 no.5
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• pp.443-459
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• 2013

Located on Java subduction zone, Merapi volcano is an active stratovolcano with a volcanic activity cycle of 1-5 years. Merapi's eruptions were relatively small with VEI 1-3. However, the most recent eruption occurred in 2010 was quite violent with VEI 4 and 386 people were killed. In this study, we have attempted to study the characteristics of Merapi's eruptions during 18 years using optical Landsat images. We have collected a total of 55 Landsat images acquired from July 6, 1994 to September 1, 2012 to identify pyroclastic flows and their temporal changes from false color images. To extract areal extents of pyroclastic flows, we have performed supervised classification after atmospheric correction by using COST model. As a result, the extracted dimensions of pyroclastic flows are nearly identical to the CVP monthly reports. We have converted the thermal band of Landsat TM and ETM+ to the surface temperature using NASA empirical formula and calculated time-series of the mean surface temperature in the area of peak temperature surrounding the crater. The mean surface temperature around the crater repeatedly showed the tendency to rapidly rise before eruptions and cool down after eruptions. Although Landsat satellite images had some limitations due to weather conditions, these images were useful tool to observe the precursor changes in surface temperature before eruptions and map the pyroclastic flow deposits after eruptions at Merapi volcano.

• Korean Journal of Remote Sensing
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• v.27 no.4
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• pp.435-444
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• 2011

The land cover map derived from spectral features of high resolution optical images has low spectral resolution and heterogeneity in the same land cover class. For this reason, despite the same land cover class, the land cover can be classified into various land cover classes especially in vegetation area. In order to overcome these problems, detailed vegetation classification is applied to optical satellite image and SAR(Synthetic Aperture Radar) integrated data in vegetation area which is the result of pre-classification from optical image. The pre-classification and vegetation classification were performed with MLC(Maximum Likelihood Classification) method. The hierarchical land cover classification was proposed from fusion of detailed vegetation classes and non-vegetation classes of pre-classification. We can verify the facts that the proposed method has higher accuracy than not only general SAR data and GLCM(Gray Level Co-occurrence Matrix) texture integrated methods but also hierarchical GLCM integrated method. Especially the proposed method has high accuracy with respect to both vegetation and non-vegetation classification.

• Korean Journal of Remote Sensing
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• v.32 no.5
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• pp.471-482
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• 2016

This paper presents an extraction method for water body which uses block-based image partitioning and extension of water body boundaries to improve the performance of supervised classification for water body extraction. The Mahalanobis distance image is created by computing the spectral information of Normalized Difference Water Index (NDWI) and Near Infrared (NIR) band images over a training site within the water body in order to extract an initial water body area. To reduce the effect of noise contained in the Mahalanobis distance image, we apply mean curvature diffusion to the image, which controls diffusion coefficients based on connectivity strength between adjacent pixels and then extract the initial water body area. After partitioning the extracted water body image into the non-overlapping blocks of same size, we update the water body area using the information of water body belonging to water body boundaries. The update is performed repeatedly under the condition that the statistical distance between water body area belonging to water body boundaries and the training site is not greater than a threshold value. The accuracy assessment of the proposed algorithm was tested using KOMPSAT-2 images for the various block sizes between $11{\times}11$ and $19{\times}19$. The overall accuracy and Kappa coefficient of the algorithm varied from 99.47% to 99.53% and from 95.07% to 95.80%, respectively.

• Journal of Korean Society for Geospatial Information Science
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• v.22 no.4
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• pp.53-61
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• 2014

Landsat OLI satellite imagery can be applied to various remote sensing applications, such as generation of land cover map, urban area analysis, extraction of vegetation index and change detection, because it includes various multispectral bands. In addition, land cover map is an important information to monitor and analyze land cover using GIS. In this paper, land cover map is generated by using Landsat OLI and existing land cover map. First, training dataset is obtained using correlation between existing land cover map and unsupervised classification result by K-means, automatically. And then, spectral signatures corresponding to each class are determined based on training data. Finally, abundance map and land cover map are generated by using iterative spectral mixture model. The experiment is accomplished by Landsat OLI of Cheongju area. It shows that result by our method can produce land cover map without manual training dataset, compared to existing land cover map and result by supervised classification result by SVM, quantitatively and visually.

• Radiation Oncology Journal
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• v.24 no.4
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• pp.211-216
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• 2006

$\underline{Purpose}$: An analysis of the infrastructure for radiotherapy in Korea was performed to establish a baseline plan in 2006 for future development. $\underline{Materials\;and\;Methods}$: The data were obtained from 61 radiotherapy centers. The survey covered the number of radiotherapy centers, major equipment and personnel. Centers were classified into technical level groups according to the IAEA criteria. $\underline{Results}$: 28,789 new patients were treated with radiation therapy in 2004. There were 104 megavoltage devices in 61 institutions, which included 96 linear accelerators, two Cobalt 60 units, three Tomotherapy units, two Cyberknife units and one proton accelerator in 2006. Thirty-five high dose rate remote after-loading systems and 20 CT-simulators were surveyed. Personnel included 132 radiation oncologists, 50 radiation oncology residents, 64 medical physicists, 130 nurses and 369 radiation therapy technologists. All of the facilities employed treatment-planning computers and simulators, among these thirty-two percent (20 facilities) used a CT-simulator. Sixty-six percent (40 facilities) used a PET/CT scanner, and 35% (22 facilities) had the capacity to implement intensity modulated radiation therapy. Twenty-five facilities (41%) were included in technical level 3 group (having one of intensity modulated radiotherapy, stereotactic radiotherapy or intra-operative radiotherapy system). $\underline{Conclusion}$: Radiation oncology in Korea evolved greatly in both quality and quantity recently and demand for radiotherapy in Korea is increasing steadily. The information in this analysis represents important data to develop the future planning of equipment and human resources.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.2
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• pp.98-106
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• 2016

Remote sensing is an efficient technology for observing and monitoring the land surfaces inaccessible to humans. This research proposes a methodology for improving the accuracy of the land cover classification using the Landsat-8 operational land imager(OLI) image. The proposed methodology consists of the following steps. First, the normalized difference vegetation index(NDVI) and normalized difference water index(NDWI) images are generated from the given Landsat-8 OLI image. Then, a new image is generated by adding both NDVI and NDWI images to the original Landsat-8 OLI image using the layer-stacking method. Finally, the maximum likelihood classification(MLC), and support vector machine(SVM) methods are separately applied to the original Landsat-8 OLI image and new image to identify the five classes namely water, forest, cropland, bare soil, and artificial structure. The comparison of the results shows that the utilization of the layer-stacking method improves the accuracy of the land cover classification by 8% for the MLC method and by 1.6% for the SVM method. This research proposes a methodology for improving the accuracy of the land cover classification by using the layer-stacking method.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.2
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• pp.88-100
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• 2013

Urban green space is one of most important aspects of urban infrastructure for improving the quality of life of city dwellers as it reduces the heat island effect and is used for recreation and relaxation. However, no systematic management of urban green space has been introduced in Korea as past practices focused on efficient development. A way to calculate the amount of green space needed to complement an urban area must be developed to preserve urban green space and to determine 'regulations determining the total amount of greenery'. In recent years, various studies have quantified urban green space and infrastructure using remotely sensed data. However, it is difficult to detect a myriad small green spaces in a city effectively when considering the spatial resolution of the data used in existing research. In this paper, we quantified small urban green spaces using CASI-1500 hyperspectral imagery. We calculated MCARI, a vegetation index for hyperspectral imagery, to evaluate the greenness of small green spaces. In addition, we applied image-classification methods, including the ISODATA algorithm and Spectral Angle Mapper, to detect small green spaces using supervised and unsupervised classifications. This could be used to categorize land-cover into four classes: unclassified, impervious, suspected green, and vegetation green.

• 한국사회정책
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• v.20 no.3
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• pp.141-170
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• 2013

The purpose of this study is to find out the relationship among the degree to provide emotional labor, personal relationship and the intent to stay of female care service workers. Specifically, this study focuses on the mediating effect of the personal relationship (client and agency relation). The path analysis and structural equation modeling analysis were performed on the collected data using SPSS18.0. and AMOS 8.0. And Sobel test conducted for examine the mediating effect. The results are the followings. First, the result of the analysis showed that agency relationship was an indirect factor as the partial mediating effect on relationship between the degree to provide emotional labor and the intent to stay for the care women workers. The result suggests that education utilizing various techniques and strategies to overcome the difficulty accompanied by emotional labor such as communication education and the government try to effort managing and controlling the agency which impact on the labor condition of care workers. Second, the government also tries to provide the trust and collaboration network system which construct a good relationship between the care worker and the agency.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.32 no.4
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• pp.5-24
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• 2021

The purpose of this study was to investigate and analyze the operating conditions of lecture contents in contactless online classes for University students. First, as a result of analyzing the responses of 93 respondents, 93.3% of the respondents took real-time online lectures (47.7%) or recorded video lectures (45.6%). Second, as a result of analyzing the contents used as textbooks, it was found that e-books (materials) and paper books (materials) were used together (36.6%), or e-books or electronic materials (36.6% and 37.6% respectively) were used in both liberal arts (47.3%) and major subjects (39.8%). In addition to textbooks, both major subjects and liberal arts highly used web materials (47.6% and 40.5% respectively) and YouTube materials (33.3% and 48.0% respectively) as external materials. Third, both liberal arts and major subjects used 'electronic files in the form of PPT or text organized and written by instructors' (62.9% and 58.1% respectively), 'internet materials' (16.7% and 19% respectively) and 'paper book or materials' (10.4% and 12.3% respectively) to share lecture contents. For the screen displayed lecture contents, 93.5% of the respondents satisfied in major subjects, and 90.2% of the respondents satisfied in liberal arts. These results suggest developing multimedia-based lecture contents and an evaluation solution capable of real-time exam supervision, developing a task management system capable of AI-based plagiarism search, task guidance, and task evaluation, and institutionalizing a solution to copyright problems for electronicizing lecture materials so that lectures can be given in the ubiquitous environment.