• Journal of Broadcast Engineering
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• v.16 no.1
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• pp.23-32
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• 2011

Design and Implementation of Clipcast Service via Terrestrial DMB This paper outlines the system design and the implementation process of clipcast service that can send clips of video, mp3, text, images, etc. to terrestrial DMB terminals. To provide clipcast service in terrestrial DMB, a separate data channel needs to be allocated and this requires changes in the existing bandwidth allocation. Clipcast contents can be sent after midnight at around 3 to 4 AM, when terrestrial DMB viewship is low. If the video service bit rate is lowered to 352 Kbps and the TPEG service band is fully used, then 320 Kbps bit rate can be allocated to clipcast. To enable clipcast service, the terminals' DMB program must be executed, and this can be done through SMS and EPG. Clipcast service applies MOT protocol to transmit multimedia objects, and transmits twice in carousel format for stable transmission of files. Therefore, 72Mbyte data can be transmitted in one hour, which corresponds to about 20 minutes of full motion video service at 500Kbps data rate. When running the clip transmitted through terrestrial DMB data channel, information regarding the length of each clip is received through communication with the CMS(Content Management Server), then error-free files are displayed. The clips can be provided to the users as preview contents of the complete VOD contents. In order to use the complete content, the user needs to access the URL allocated for that specific content and download the content by completing a billing process. This paper suggests the design and implementation of terrestrial DMB system to provide clipcast service, which enables file download services as provided in MediaFLO, DVB-H, and the other mobile broadcasting systems. Unlike the other mobile broadcasting systems, the proposed system applies more reliable SMS method to activate the DMB terminals for highly stable clipcast service. This allows hybrid, i.e, both SMS and EPG activations of terminals for clipcast services.

• Restorative Dentistry and Endodontics
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• v.28 no.1
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• pp.80-88
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• 2003

Object The purpose of this study were to evaluate the microtensile bond strength of resin fiber reinforced post to radicular dentin using resin cement according to various dentin surface treatment and to observe the inter face between post and root dentin under SEM Material and Method A total 16 extracted human single rooted teeth were used. A lingual access was made using a #245 carbide bur in a high-speed handpiece with copious air water spray. The post space was mechanically enlarged using H-file(up to #60) and Gates Glidden bures(#3). This was followed by refining of the canal space using the calbrating drill set provided in ER Dentinpost(GEBR, BRASSELER GmbH&Co. KG). The 16 teeth were randomly distributed into 4 group of 4 teeth. Group 1 teeth had their post space prepared using 10% phosphoric acid as root canal surface treatment agent during 20s. The canal was then rinsed with saline and dried with paper point. Group 2 teeth had their post space prepared using 3% NaOCl as root canal surface treatment agent during 30min. The canal was then rinsed with saline and dried with paper point. Group 3 teeth had their post space prepared using 17% EDTA as root canal surface treatment agent during 1min. The canal was then rinsed with saline and dried with paper point. Group 4 teeth had their post space prepared using 17% EDTA as root canal surface treatment agent during 1min. After rinsing with saline, the canal was rinced 10m1 of 3% NaOCl for 30min. After drying with paper point, the post(ER Dentinpost, GEBR, BRASSELER GmbH&Co. KG) was placed in the treated canals using resin cement. Once the canal was filled with resin cement(Super bond C&B sunmedical co. Ltd.), a lentulo was inserted to the depth of the canal to ensure proper coating of the root canal wall. After 24 hours, acrylic resin blocks($10{\cdot}10{\cdot}50mm$) were made. The resin block was serially sectioned vertically into stick of $1{\cdot}1mm$. Twenty sticks were prepared from each group. After that, tensile bond strengths for each stick was measured with Microtensile Tester. Failure pattern of the specimen at the interface between post and dentin were observed under SEM. Results 1. Tensile bond strengths(meen{\pm}SD$) ) were expressed with ascending order as follows group 4, $12.52{\pm}6.60$ ; group 1, $7.63{\pm}5.83$ ; group 2, $4.13{\pm}2.31$ ; group 3, $3.31{\pm}1.44$. 2. Tensile bond strengths of Group 4 treated with 17% EDTA +3%NaOCl were significant higher than those of group 1, 2 and 3 (p<0.05). 3. Tensile bond strengths of Group 1 treated with 10% phosphoric acid were significant higher than those of group 2 (p<0.05). Tensile bond strengths of Group 4 treated with 17% EDTA +3% NaOCl was significant higher than those of other groups.

• The Korean Journal of Archival Studies
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• no.6
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• pp.225-262
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• 2002

Chief Consultant Archives Government Archives & Records Service -table of contents- 1. Introduction 2. Relationship of Historical Studies and Archive 3. Relationship of Archives and Archives 4. Conclusion; Historians, Archives, and Archivists, and Their Roles This essay is mainly written for historians who may have "little or limited experience" in dealing with archives and archivists in their course of historical research. It may sound very ridiculous to say that "historians have little or limited experience" in using archives but it is also true that many Korean historians have depended on various compiled editions of historical materials or personally donated and/or collected materials when they do research, rather than they would visit archives and search for the materials by themselves. This is the main reason for that the public archives in Korea have not served historians well and effectively, and vice versa, that historians have not visited archives sometime with no knowledge of archives, and have not requested opening of archives for their research. It is a simple fact that historian's study depends on the records he/she uses. Without records, there should be no history. Use of archives for historical research is a common thing and a must in modern archives. Records are selected to be preserved in archives for their preservation as well as their future use. Who select the records as archives? Archivists do mostly. Then, what are the criteria for the archivists to chose records as permanent preservable archives? Answers to this fundamental question have been provided by many historians and archivists. The closest answer may be that selecting archivists would be better trained and equipped with historical research and knowledgeable of the major trends in historical research. With his/her own experience of historical research and tracing the trends of historical studies and materials used in the historiography, they could chose better and appropriate records for future use using their prudence and discretion. It also means that historians have had influence on archivists in their selecting archives by providing the theme and context of historical studies of the time. Though not necessarily becoming a historian themselves, selecting or appraising archivists should understand the process of creating the records and should know how they become archives. This is a precondition to become a good archivist. But that's not all. They must know how the archives are used and what archives are used for what purposes. Among many other roles of modern archivists, selecting and describing the archives are the foremost tasks of an archivist. Archivists therefore developed modern methods to select future archives based on functional analysis and records series concept rather than a record file or item as a unit of selection. Historians are users or consumers of the archives held in the archives building or repository. The quality of their study depends on the "quality" of the materials they use. With the help of archivists not to mention of reference service, historians owe much to archivists in having an access to the materials they need, intellectually and physically. Too many closed archives and too long closed archives in the archives repository would benefit neither historians nor archivists. However, archivists can mostly react only to archive requests and demands made by historians for more wide accessibility. Using the FOIA, as in the U.S., or the Information Opening Act, as in case of Korea, historians can promote the use of historical materials as well as promoting accountability and transparence for the benefit to society as whole. In this context, it is vary desirable to establish a close professional relationship between historians and archivists even in the age of information society. At present, historians need more understanding of operation and importance of archives while archives administration need to realize the potential archival demands from research community and civil movement for clean government.

• Journal of Intelligence and Information Systems
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• v.29 no.3
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• pp.57-78
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• 2023

COVID-19, which started in Wuhan, China in November 2019, spread beyond China in 2020 and spread worldwide in March 2020. It is important to prevent a highly contagious virus like COVID-19 in advance and to actively treat it when confirmed, but it is more important to identify the confirmed fact quickly and prevent its spread since it is a virus that spreads quickly. However, PCR test to check for infection is costly and time consuming, and self-kit test is also easy to access, but the cost of the kit is not easy to receive every time. Therefore, if it is possible to determine whether or not a person is positive for COVID-19 based on the sound of a cough so that anyone can use it easily, anyone can easily check whether or not they are confirmed at anytime, anywhere, and it can have great economic advantages. In this study, an experiment was conducted on a method to identify whether or not COVID-19 was confirmed based on a cough sound. Cough sound features were extracted through MFCC, Mel-Spectrogram, and spectral contrast. For the quality of cough sound, noisy data was deleted through SNR, and only the cough sound was extracted from the voice file through chunk. Since the objective is COVID-19 positive and negative classification, learning was performed through XGBoost, LightGBM, and FCNN algorithms, which are often used for classification, and the results were compared. Additionally, we conducted a comparative experiment on the performance of the model using multidimensional vectors obtained by converting cough sounds into both images and vectors. The experimental results showed that the LightGBM model utilizing features obtained by converting basic information about health status and cough sounds into multidimensional vectors through MFCC, Mel-Spectogram, Spectral contrast, and Spectrogram achieved the highest accuracy of 0.74.