• Journal of KIISE:Databases
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• v.31 no.3
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• pp.274-286
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• 2004

In mobile client-server environments, mobile clients usually are disconnected with their server because of high cost of wireless communication and keep their own local copies to provide efficient updating the cached map. The update of the server database leads to invalidation of the cached map in the client side. To solve the issues of invalidation of the cached map, it is not efficient to resend part of the updated server database to clients whenever the updating of the server database occurs. This paper proposes a log-based update propagation method to propagate the server's update into its relevant clients by using only update logs. Too many logs increasingly accumulate as the sever database is updated several times. The sequential search of the relevant log data for a specific client is time-consuming. Sending of unnecessary logs should be avoided for reducing the overhead of communication.'re solve these problems, we first define unnecessary logs and then suggest log reduction methods to avoid or cancel creating unnecessary logs. The update log index is used for quickly retrieving relevant logs.

• Journal of Digital Convergence
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• v.17 no.1
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• pp.433-442
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• 2019

We have developed art and career convergence class for career recognition through drawing a neighborhood job map. Thus, we want to expand the students' career recognition. 3 Classes were conducted in 16 elementary school students from 5th to 6th. Through pre & post-questionnaire, and the interviews with the students' work, job recognition with job value and job prejudice, self-understanding and career attitude were analyzed. As follows. First, students' job recognition was expanded. The ability to identify the needs, values and purposes of jobs has improved. Changes in job values that all jobs are worth have occurred and job bias has changed. Second, the career attitude changed on the basis of self-understanding. Thus, in the context of deciding the job demanded by the society rather than the student's will, art and career convergence class was effective in career recognition.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.6
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• pp.785-791
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• 2021

In this paper, we propose a methodology for estimating the optimal traversable destination from the location-based information of the object recognized by the mobile robot to perform the object delivery service. The location estimation process is to apply the generalized Voronoi graph to the grid map to create an initial topology map composed of nodes and links, recognize objects and extract location data using RGB-D sensors, and collect the shape and distance information of obstacles. Then, by applying the hybrid approach that combines the center of gravity and thinning method, the optimal moving position for the service robot to perform the task of grabbing is estimated. And then, the optimal node information for the robot's work destination is updated by comparing the geometric distance between the estimated position and the existing node according to the node update rule.

• Korean Journal of Child Education & Care
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• v.17 no.4
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• pp.187-208
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• 2017

This study surveyed 60 early childhood teachers at the kindergartens and day care centers in Incheon Metropolitan City to examine the contents and extent of the teachers' knowledge on early childhood history education by using the definition map designed by Novak and Gowin(1984). To be more specific, the researcher asked the participating teachers through group meetings to draw the definition maps and analyzed them. The results were as follow. First, 11 categories for high level definition of early childhood history education used by early childhood education were identified, among which the most frequently used high level definition were 'life style' followed in order by 'culture/art' and 'great men.' Second, in terms of the average number of dependent definitions included in the given high level definitions, the largest was 'life style' which was followed in order by culture/art, activity methods. It means that the widest area of early childhood teachers' knowledge on early childhood history education was about 'life style,' while it shows that the extent of knowledge on teaching-learning methods was relatively wide. However, in the case of great men, although it was frequently recognized in the high level of definition it was not so in the dependent definitions, meaning the extent of their knowledge was rather narrow. Scholars explain that the higher the teachers' attention and knowledge about the content of curriculum the more options of teaching method they tend to employ to teach in a more extensive and diverged way. Therefore, in order to improve early childhood education, efforts should be more focused on deepening and systemizing the knowledge of early childhood teachers.

• Journal of Korea Multimedia Society
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• v.16 no.6
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• pp.764-781
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• 2013

In this paper, we propose a highly precise vehicle detection method with low false alarm using billboard sweep stereo matching and multi-stage hypothesis generation. First, we capture stereo images from cameras established in front of the vehicle and obtain the disparity map in which the regions of ground plane or background are removed using billboard sweep stereo matching algorithm. And then, we perform the vehicle detection and tracking on the labeled disparity map. The vehicle detection and tracking consists of three steps. In the learning step, the SVM(support vector machine) classifier is obtained using the features extracted from the gabor filter. The second step is the vehicle detection which performs the sobel edge detection in the image of the left camera and extracts candidates of the vehicle using edge image and billboard sweep stereo disparity map. The final step is the vehicle tracking using template matching in the next frame. Removal process of the tracking regions improves the system performance in the candidate region of the vehicle on the succeeding frames.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.6
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• pp.517-526
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• 2017

In this study, we analyzed the accuracy of elevation, slope, and area to the damage scale of the debris flow using the drones to track the details of the debris flow that method was between the digital topographical map(1/5,000) method and GPS ground survey method. The results are summarized as follows. At first, in the comparison of elevation, the value by the drones was 3.024m lower than the digital topography map, but in case of slope the average slope was $1.20^{\circ}$ and the maximum slope was $10.46^{\circ}$ which was higher by the drones image. Secondly, the difference area is $462m^2$ between on the digital topographic map and the drones image was calculated high, because it is determined by reflecting the uplift of the terrain as a point that calculated more accurate than the digital topographic map. Therefore, when compared with the existing method, the drone image method was very effective in terms of time and manpower.

• Journal of Broadcast Engineering
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• v.11 no.4 s.33
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• pp.471-482
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• 2006

In this paper, we propose a new scheme to generate multi-view images utilizing depth map decomposition and adaptive edge smoothing. After carrying out smooth filtering based on an adaptive window size to regions of edges in the depth map, we decompose the smoothed depth map into four types of images: regular mesh, object boundary, feature point, and number-of-layer images. Then, we generate 3-D scenes from the decomposed images using a 3-D mesh triangulation technique. Finally, we extract multi-view images from the reconstructed 3-D scenes by changing the position of a virtual camera in the 3-D space. Experimental results show that our scheme generates multi-view images successfully by minimizing a rubber-sheet problem using edge smoothing, and renders consecutive 3-D scenes in real time through information decomposition of depth maps. In addition, the proposed scheme can be used for 3-D applications that need the depth information, such as depth keying, since we can preserve the depth data unlike the previous unsymmetric filtering method.

• Food Science and Preservation
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• v.8 no.1
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• pp.1-8
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• 2001

Effects of storage method and duration on the post-storage quality changes of deastringencied persimmons were investigated. Astringent persimmons(Diospyros kaki T. cv. Chungdobansi) were treated for 39 hours in 70% CO$_2$+5% O$_2$ at 25 $\^{C}$ for astringency removal, and then stored in CA(5%CO$_2$+3%O$_2$, 8%CO$_2$+3%O$_2$), MAP(0.06 mm LDPE film, 5.2%CO$_2$+6.8%O$_2$) and air at 0$\^{C}$ for 15, 45, 75 arnd 105 days. Subsequent to the storage, persimmons were held in air at 10$\^{C}$ for 4 days. The difference of firmness loss in relations to storage methods at O$\^{C}$ during holding at 10$\^{C}$ observed in fruits stored above 45 days at 0$\^{C}$, CA(8%CO$_2$+3%O$_2$) storage was more retarded the firmness loss than the others. Soluble solids during holding at 10$\^{C}$ trended to decrease in fruits stored above 75 days at 0$\^{C}$, CA and MAP storage were a little effective to keeping soluble solids. Titratable acidity during holding at 10$\^{C}$, decreased in fruits stored until 75 days at 0$\^{C}$ regardless storage methods. Sensory characteristics, color, hardness and overall acceptability of fruits stored in CA were significantly higher than those of fruits stored in MAP and air during shelf-life at 10$\^{C}$ after long-term storage at 0$\^{C}$ . These results show that the storage conditions had residual effect on the quality of deastringencied persimmons during shelf-life after long-term storage.

• Journal of Broadcast Engineering
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• v.18 no.6
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• pp.859-871
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• 2013

In this paper, we propose an algorithm that generates multi-view images by grid-mesh based image domain warping using occlusion mask and various image features obtained from the stereoscopic images. In the proposed algorithm, we first extract image saliency map, line segments and disparity saliency map from stereo images and then get them through a process that improves the quality of extracted features. This process is accomplished in two steps. In the first step, reliability of disparity saliency map on object boundary regions is enhanced by using occlusion information. And in the second step, we enhance the quality of image features in terms of temporal consistency by using temporal consistency information for stereo images. With these enhanced features, multi-view images are generated by grid-mesh based image domain warping technique. Experimental results show that the proposed algorithm performs better than existing algorithms in terms of visual quality.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.3
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• pp.239-247
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• 2022

Cities are becoming more complex due to rapid industrialization and population growth in modern times. In particular, urban areas are rapidly changing due to housing site development, reconstruction, and demolition. Thus accurate road information is necessary for various purposes, such as High Definition Map for autonomous car driving. In the case of the Republic of Korea, accurate spatial information can be generated by making a map through the existing map production process. However, targeting a large area is limited due to time and money. Road, one of the map elements, is a hub and essential means of transportation that provides many different resources for human civilization. Therefore, it is essential to update road information accurately and quickly. This study uses Semantic Segmentation algorithms Such as LinkNet, D-LinkNet, and NL-LinkNet to extract roads from drone images and then apply hyperparameter optimization to models with the highest performance. As a result, the LinkNet model using pre-trained ResNet-34 as the encoder achieved 85.125 mIoU. Subsequent studies should focus on comparing the results of this study with those of studies using state-of-the-art object detection algorithms or semi-supervised learning-based Semantic Segmentation techniques. The results of this study can be applied to improve the speed of the existing map update process.