• Journal of KIISE:Computer Systems and Theory
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• v.31 no.5_6
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• pp.297-304
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• 2004

In this paper, a mesh simplification algorithm based on wavelet transform and 2D planar sampling is proposed for efficient handling of 3D objects in computer applications. Since 3D vertices are directly transformed with wavelets in conventional mesh compression and simplification algorithms, it is difficult to solve tiling optimization problems which reconnect vertices into faces in the synthesis stage highly demanding vertex connectivities. However, a 3D mesh is sampled onto 2D planes and 2D polygons on the planes are independently simplified in the proposed algorithm. Accordingly, the transform of 2D polygons is very tractable and their connection information Is replaced with a sequence of vertices. The vertex sequence of the 2D polygons on each plane is analyzed with wavelets and the transformed data are simplified by removing small wavelet coefficients which are not dominant in the subjective quality of its shape. Therefore, the proposed algorithm is able to change the mesh level-of-detail simply by controlling the distance of 2D sampling planes and the selective removal of wavelet coefficients. Experimental results show that the proposed algorithm is a simple and efficient simplification technique with less external distortion.

• Journal of KIISE:Databases
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• v.32 no.3
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• pp.276-284
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• 2005

In the mobile computing environment, caching data at the client's side is a useful technique for improving the performance. For caching to be effective, the cache contents must be consistent with those stored in the server. That is, unfortunately, difficult to enforce due to the frequent disconnection and mobility of clients. In the literature, the basic approach adopted is for the sever to periodically broadcast invalidation reports(IRs) that contain information about objects that have been updated recently. However IR-based cache maintenance scheme has a main drawback. Any client who has been disconnected longer than w seconds has to discard all cached items even some of them may still be valid. In this paper, we propose two main schemes which can adapt clients' losing IR messages by long disconnection. First, the client sends its disconnection time when connection is re-established, and the server uses this information to decide the size of broadcast window w dynamically. Second, the server maintains IR messages for a given period of time and a client who has been disconnected longer than w seconds can verify its cache consistency individually. Compared to previous IR-based schemes, our schemes can significantly reduce cache missing and uplink request and improve the throughput by reducing response time.

• Journal of Advanced Navigation Technology
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• v.9 no.1
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• pp.48-55
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• 2005

In this paper, we propose an efficient moving object tracking technique for multi-camera surveillance system. Color CCD cameras used in this system are network cameras with their own IP addresses. Input image is transmitted to the media server through wireless connection among server, bridge, and Access Point (AP). The tracking system sends the received images through the network to the tracking module, and it tracks moving objects in real-time using color matching method. We compose two sets of cameras, and when the object is out of field of view (FOV), we accomplish hand-over to be able to continue tracking the object. When hand-over is performed, we use MHI(Motion History Information) based on color information and M-bin histogram for an exact tracking. By utilizing MHI, we can calculate direction and velocity of the object, and those information helps to predict next location of the object. Therefore, we obtain a better result in speed and stability than using template matching based on only M-bin histogram, and we verified this result by an experiment.

• Journal of Intelligence and Information Systems
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• v.15 no.2
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• pp.49-59
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• 2009

Contents-based image retrieval methods are in general more objective and effective than text-based image retrieval algorithms since they use color and texture in search and avoid annotating all images for search. SIM(Self-organizing Image browsing Map) is one of contents-based image retrieval algorithms that uses only browsable mapping results obtained by SOM(Self Organizing Map). However, SOM may have an error in selecting the right BMU in learning phase if there are similar nodes with distorted color information due to the intensity of light or objects' movements in the image. Such images may be mapped into other grouping nodes thus the search rate could be decreased by this effect. In this paper, we propose an improved SIM that uses HSV color model in extracting image features with color quantization. In order to avoid unexpected learning error mentioned above, our SOM consists of two layers. In learning phase, SOM layer 1 has the color feature vectors as input. After learning SOM Layer 1, the connection weights of this layer become the input of SOM Layer 2 and re-learning occurs. With this multi-layered SOM learning, we can avoid mapping errors among similar nodes of different color information. In search, we put the query image vector into SOM layer 2 and select nodes of SOM layer 1 that connects with chosen BMU of SOM layer 2. In experiment, we verified that the proposed SIM was better than the original SIM and avoid mapping error effectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.18-25
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• 2020

With the development of water internet technology, data communication between objects is expanding. Research related to data communication technology between vehicles that incorporates related technologies into vehicles has been actively conducted. For data communication between mobile terminals, data stability, reliability, and real-time performance must be guaranteed. The 5 GHz Wi-Fi band, which is advantageous in bandwidth, communications speed, and wireless saturation of the wireless network, was selected as the data communications network between vehicles. This study analyzes how to design and implement a 5 GHz Wi-Fi network in a vehicle network. Considering the characteristics of the mobile communication terminal device, a continuous variable communications structure is proposed to enable high-speed data switching. We simplify the access point access procedure to reduce the latency between wireless terminals. By limiting the Transmission Control Protocol Internet Protocol (TCP/IP)-based Dynamic Host Configuration Protocol (DHCP) server function and implementing it in a broadcast transmission protocol method, communication delay between terminal devices is improved. Compared to the general commercial Wi-Fi communication method, the connection operation and response speed have been improved by five seconds or more. Utilizing this method can be applied to various types of event data communication between vehicles. It can also be extended to wireless data-based intelligent road networks and systems for autonomous driving.

• The KIPS Transactions:PartC
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• v.11C no.3
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• pp.379-386
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• 2004

The WAP 2.0 system is a newly proposed wireless communication system by the WAP Forum for interoperability across Internet environment and the system takes charge of communication between WAP terminals and existing origin Web servers. The purpose of this paper is 1) to construct a WAP 2.0 proxy proposed by the WAP Forum and 2) to improve the WAP Proxy in order to increase communication efficiency between wired and wireless communication objects. The Improved WAP proxy constructed in this study provides links between wired and wireless communication environments using the split-TCP concept. However, unlike the split-TCP connection, The improved WAP proxy maintains TCP's end-to-end semantics and reduces overhead by avoiding operations as much as possible on the upper protocol layer. In addition, The improved WAP proxy supports SACK(Selective Acknowledgement ) option and Timestamp option for speedy re-transmission which leads to reduction of performance degradation. After constructing the improved WAP proxy under Linux environment, experiments have been taken. The experimental results show that, compared with the experiments when a WAP proxy proposed by the WAP Forum is used, both data transmission delay time and data transmission size decrease to show that communication efficiency is increased. In particular, as packet missing ratio Increases, data transmission size decreases, which demonstrates that the improved WAP proxy is very effective for performance improvement in wireless communication environment.

• Journal of The Korean Association For Science Education
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• v.42 no.2
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• pp.239-252
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• 2022

This study aims to develop performance criteria based on characteristics observed in science inquiry tasks for elementary school students. First, the performance characteristics by observing 70 fifth-grade elementary school students' science inquiry activity report are listed. Second, the checklist-type scoring criteria in connection with the theoretical framework of scientific inquiry process and relevant competencies are developed. Third, with the developed scoring criteria, 11 raters participate in scoring 350 students' reports. The main findings are as follow: first, the scoring data are well-fitted for the many-faceted Rasch model, and 22 scoring criteria are reasonably-well differentiated for various levels of proficiency. Second, at low performance level, observable characteristics are to answer questions explicitly required by the task or to observe objects or phenomena using pre-learned scientific concepts, while at high performance level, to explore additional data other than given data or to reflect on one's experimental process. Based on the results, the usefulness of analyzing students' performance characteristics for developing the scoring criteria, and further research directions are discussed.

• The Journal of Korean society of community based occupational therapy
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• v.4 no.1
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• pp.59-73
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• 2014

Objective : The purpose of this study is to understand Lived Experience of Suffering for family of victim with Sewol-ho ferry accident and to suggest the necessity of mental health occupational therapy regarding of psychological trauma of family of victim. Methods : This study was applied with Parse's Human becoming research method to recognize experience pain for 5 objects losing family with with Sewol-ho ferry accident. According to Parse's research mothod, secondary data, documentary video about experience pain of family of victim with Sewol-ho ferry accident was selected and analyzed. Results : Three core concept for lived experience of suffering of family with victim with Sewol-ho ferry accident as below statements. 1. Despair and sadness losing family, 2. Impotent feeling and guilty conscience breaking down daily life, 3. Seeking relief from suffering for remaining family. Although there were extreme impotent feeling of losing family with Sewol-ho ferry accident, structural conversion presented as process with denial reality which do not want to accept a death in the family and standing for remaining family. The conceptual integration was expressed to powering from valuing and languaging to connection-separation, revealing-concealingl. Conclusion : Family of victim with Sewol-ho ferry accident is losing meaning of life the goal of life with impotent feeling, despair and depression. It is urgently needed for mental health occupational therapy program to restore disruptive everyday activity and participation in community by developing occupational therapy program through meaningful occupation to family of victim.

• The Journal of Fisheries Business Administration
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• v.19 no.2
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• pp.1-58
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• 1988

The purpose of this study is to investigate the relation between social education and secondary education of seaside and sea village schools for supporting the successors to fishery. Objects of the study were five groups; 321 fishermen, 107 staff members of a Fishery Guidance Center, 1, 001 students, 306 teachers of sea villages, 193 staff members of a Fishery Cooperative Association. The total number of people being object of this study was 1, 876 persons. The questionaire used for this study was made after preliminary counseling with fishermen in sea villages and teachers in seaside schools. The results of this study are as follow ; 1) About the value of Fishery and successors to Fishery There have been more positive responses than negative ones to the question on the value of fishery. The main reason for positive responses lies in the potentiality for development of fishery but the negative responses are because of the heavy work. 56.8% of the respondents expected an increasing number of successor to fishery, but 43.2% of the respondents had a negative foresight on that problem. The negative respondents stated that the fisherman that moved from the sea villages to the urban areas are responsible for the none increasing numbers of successors to fishery. Most of the respondents answered that government support is needed in order to increase the number of successors to fishery. 2) Social education for Fishermen Only 40% of fishermen know the Fishing Village Guidance Center as the main institute for social education. 94.17% of the respondents prefer plural institutes to single ones. 5.9% of the respondents answered with opposit opinions. 40.4% of the respondents answered that technical teachings has not often been practised. The reason why technical teaching does not often come into effect are as follows; lack of technical expertise, insufficient concern of staff members of the Guidance Center or the Cooperation Association. Also fishermen answered that the Fisherman Guidance Center does not often practise technical education. The Fishery Cooperation Association with its social education for fisherman takes the role of education for the economical way and carries out financial assistance. The relationship between the Fishery Cooperative Association and fishermen is presented satisfactory. However, the frequency of education is not satisfactory. Indifferences between staff members of the Fishery Cooperative Association does not carry out fishery education very often. Also loaned money matters were not satisfactory. 3) Secondary education for Fishery This study showed that it is desirable that the practical course of middle schools in islets and seaside villages take education on fishery ; however, a few schools only take the practical course fishery. Most of the fishery high schools want computer education as a new recommendable course. The students of fishery high schools want computer education as a new recommendable course. The students of fishery high schools have problems with scientific terms in the text books for the practical of fishery high schools have problems with scientific terms in the text books for the practical courses. Over 80% of the respondents agreed that the principals of schools in islets and sea side villages should be men having majored in fishery. 4) The connection between social education and secondary education for fishery a. It is desirable that the principal and vice principal of secondary schools in islets and sea side villages are men majored in fishery. b. It is recommendable that fishery courses are taken as practical courses in fishery village schools for it is helpful to relate between the vocation and the district's special character, as well as to built up relation between the middle school education and the fishery high school education. c. The teachers of fishery high schools and the officials of government offices which are related to fishery should work together to realize a program on teaching various kinds of techniques and give other useful informations to fishermen. d. During the vacations the fishery high school could be used for the social education of fishermen. Seminars on fishery technique and cultural aspects could be held. Especially a spiritual education which is needed for the improvement of the society of fishermen could be achieved by a cultural education. e. On the state level a financial support to raise the number of successors to fishery, a national policy for the betterment of the life of fishermen, as well as active publicity activities are necessary. f. A financial support of the government for raising the number of the successors to fishery is needed. For this purpose a fishery education performed on a state level would be desirable.

• Journal of Korean Elementary Science Education
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• v.43 no.1
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• pp.122-135
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• 2024

The purpose of this study was to analyze the examples presented in the "Separation of Mixtures" section of the 2015 revised science authorized textbook introduced in elementary schools in 2022 and to see how the teachers and students understand the concept. To do that, 96 keywords were extracted through three cleansing processes to separate the elements of the mixture presented in the textbook. In order to analyze the teachers' perceptions, 32 teachers at elementary schools in Gyeonggi-do received responses to a survey, and a survey of 92 fourth graders who learned the separation of the mixture with an authorized textbook in 2022 was used for the analysis. As a result, as for the solids, 54 out of 96 separations (56.3%) showed the highest ratio, and the largest number of cases were presented according to the characteristics of the development stage of students. It was followed by living things, liquids, other objects and substances, and gasses. By analyzing the mixture, the structure and the interrelationships between the 96 extracted keywords were systematized through the network analysis, and the connection between the keywords, which were a part of the mixture was analyzed. The teachers partially responded to the separation of the complex mixture presented in the textbook, but most of the students did not recognize it. Because the analysis of the teachers' and students' perceptions of the seven separate categories presented in the survey was not based on a clear conceptual perception of the separation of the mixture, but rather they tended to respond differently for each characteristic of each individual category, it was decided that it was necessary to present clearer examples of the separation of the mixture, so that the students could better understand the concept of separation of mixtures that could be somewhat abstract.