• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.8
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• pp.3121-3135
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• 2015

Owing to the increase in consumption of multimedia content and the improvement of device capacity, user demand for high-quality content has increased. However, it is difficult to transport such large amounts of content over the existing broadcasting network with limited bandwidth. To provide high-definition broadcasting, some studies suggest methods of transporting multimedia over heterogeneous networks after encoding content hierarchically. MPEG Media Transport (MMT), standardized by Moving Picture Experts Group (MPEG), is a solution that enables large-volume media transport over heterogeneous networks such as digital broadcasting networks and packet-switched networks. In the case of delivering a scalable encoded video over different networks, synchronization of each stream is an important issue. MMT defines a synchronization scheme, but does not contain sufficient functions to implement it. In this paper, we propose a synchronization scheme for media streams that are encoded hierarchically, divided into layers, and transported over heterogeneous networks. We implement our scheme using MMT and HTTP, and experimented using three encapsulated video streams with different durations. As a result, we show that the proposed scheme can reduce the waiting time to display high-quality video, relative to Dynamic Adaptive Streaming over HTTP-Scalable Video Coding (DASH-SVC) by requesting segments of enhanced layers after calculating the transmission time. Additionally, we find out that the selection of durations have a relation to the characteristics of the video.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.397-399
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• 2017

The HDB3 code, a type of line code, is a data coding method used for digital data transmission. It is used to remove the DC wander on the transmission line which occurs when the DC component data is transmitted continuously. The military tactical communication network uses HDB3 code for data transmission and develops equipment using commercial HDB3 Codec IC. Because it is operated for more than 10 years due to the characteristics of military equipment, if a failure occurs in the equipment, the equipment can not be repaired due to the discontinuance of the part, so that the entire equipment may not be used. In this paper, we implement the HDB3 Codec as a logic to solve this problem and verify that the performance is equivalent to that of commercial parts.

• Journal of Broadcast Engineering
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• v.6 no.3
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• pp.215-224
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• 2001

In recent days, research activities on multimedia services mainly focus on the multiplexing system with timing synchromization for media components, such as video, audio and text. The MPEG-4 standard emphasizes object-based coding which includes analysis and understanding of the Image content. Since in MPEG-4 we can define objects and encode them independently, we can manipulate and display each object for different applications. This feature of MPEG-4 is also vero useful for multimedia services, such as video streaming cia different network channels, digital versatile disc, internet TV, video E-mail, and so on. In this Paper, we implement a multimedia streaming system which is compliant with the MPEG-4 system and the MP4 file format.

• The Journal of the Acoustical Society of Korea
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• v.14 no.1E
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• pp.30-38
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• 1995

In this paper, we evaluated the performance of vocoders for three-way conferencing using signal summation technique in digital mobile communication network. The signal summation technique yields natural mode of three-way conferencing, in shich the mixed voice signal from two speakers are transmitted to a third person, though there has been no useful speech coding technique for the mixed voice signal yet. We established Qualcomm code term prediction (RPE-LTP) vocoders to provide three-way conferencing using signal summation techinique. In addition, as the conventional speech quality measures are not applicable to the vocoders for mixed voice signals, we proposed two kinds of subjective quality measures. These are the sentence discrimination (SD) test and the modified degraded mean opinion score (MDMOS) test. The experimental results show that the output speech quality of the VSELP vocoder is superior to other two.

• Journal of Digital Convergence
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• v.12 no.2
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• pp.513-518
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• 2014

According to the development of IT technology, various new technologies are being produced. As the complexity of the information system like using the network and convergence devices is increasing, threat and vulnerability against various security problems are increasing even though new IT services provide the convenience of users' accessibility to services. In order to secure the safety of information system, the weakness is being removed through the information protection vulnerability analysis starting from information and communication service construction stage and the system is being prepared for pre-inspection activities about whether the information protection measures were established and applied. In this paper, introduction and current status of each country about advanced check-up systems in the information system are to be identified. Progress direction about the advanced pre-inspection system which is driven by Korea Internet Security Agency and its activation plan to secure the safety are to be suggested.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.3
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• pp.11-19
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• 2015

Due to recent development in mobile devices, the mobile device utilization and many related applications have been increasing. Most of initial applications on mobile devices just showed simple information, but now they processes huge data. However, smart devices have certain limitations in processing massive data. Especially, if the size of data increases, the speed of data processing adversely decreases, so the performance of programs also decreases. If hardware specification of the mobile devices is not enough to handle it, response time will be drastically delayed. To overcome these drawbacks, most of application running on mobile devices communicate with their servers to manage data. XML is a proper language for data communication to send and receive data between servers and mobile devices, because it defines rules of document's format and it is a textual data format and small-sized language. However, mobile devices have limitation such as memory, CPU and wireless network to process huge data and XML also takes a lot of time to communicate with servers and devices and handle data, so it could be overhead in service time. Binary XML is an alternative of performance improvement in data processing, which has XML's benefits and minimizes the XML size by binary coding. However, most of binaryXML which are used on applications don't fit on mobile applications. In this paper, we surveyed many kinds of binaryXML, compared merits and demerits to find a binaryXML for mobile applications. We propose how to use binary XML and implemented an electronic attendance system using binary XML to overcome the limitation of XML and to reduce the load of data communications between servers and devices.

• Journal of Chest Surgery
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• v.25 no.10
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• pp.989-1000
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• 1992

The concepts of modern type computer are so called "General purpose, stored program and digital computer" that is proposed by Charles Babbage. ENIAC, the initial operational electronic digital computer model, was produced in 1946. During the last 50 years, an epoch-making development of the personal computer was marked. The computerization of all levels of society is going on and also computerization of the general hospital and medical college is developing. But patient data management system for clinician is not used generally. We suggest the use of computer aided data management application programs for the clinical informations of the patients of the Department of Thoracic and Cardiovascular Surgery for better management and to make best of medical informations, to co-operate with the current of this times, and to prepare against the Hospital Information Systems[HIS], actively. Also, we suggest to standardize the format and structure of database files to store the clinical data of the patients By standardization of the database files, we can integrate and relate the data of the individual department or hospital, build up the regional or national statistics of the patients easily, and promote the generation of application programs. The medical network by the communication and computer would be utilized to collect the database files. And finally, we suggest the use of code system to input and search the informations about the diagnosis and operation such as the code system of International Classfication of Disease[WHO] and the table of the classfication of operation of the Ministry of Health and Social Affairs, Korea. In this article, we tried to show the new standards, the essential items for computerization of clinical informations of the patients of the Department of Thoracic and Cardiovascular Surgery.r Surgery.

• Journal of Digital Convergence
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• v.18 no.11
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• pp.19-29
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• 2020

The study aims to examine the effectiveness of flipped learning teaching methods by using learning analytics to enable effective programming learning for non-major students. After designing a flipped learning programming class model applied with the ADDIE model, learning-related data of the lecture support system operated by the school was processed with crawling. By providing data processed with crawling through a dashboard so that the instructor can understand it easily, the instructor can design classes more efficiently and provide individually tailored learning based on this. As a result of analysis based on the learning-related data collected through one semester class, it was found that the department, academic year, attendance, assignment submission, and preliminary/review attendance had an effect on academic achievement. As a result of survey analysis, they responded that the individualized feedback of instructors through learning analysis was very helpful in self-directed learning. It is expected that it will serve as an opportunity for instructors to provide a foundation for enhancing teaching activities. In the future, the contents of social network services related to learners' learning will be processed with crawling to analyze learners' learning situations.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.11
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• pp.19-29
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• 2001

The Pan-European Digital Audio Broadcasting(DAH) system's performance is characterized and improved with the aid of turbo codec. From the fact that the first bit among the four coded bits at the RCPC coding defined in the Eureka 147 DAD system is not. punctured and always transmitted, this paper proposes a new turbo coded DAB system model that replaces the existing RCPC codec by a turbo codec without modifying the puncturing procedure and puncturing vectors defined in the standard DAB system for compatibility. The performance of a new system is compared to that of the conventional system under the Rician fading channel and the Rayleigh fading channel in conjunction with DAD transmission mode I and III suitable for the terrestrial single frequency network and satellite broadcasting.

• The Journal of the Acoustical Society of Korea
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• v.21 no.6
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• pp.566-575
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• 2002

Low-titrate audio coding enables a number of Internet and mobile multimedia streaming service more efficiently. For the help of next-generation mobile telephone technologies and digital audio/video compression algorithm, we can enjoy the real-time multimedia contents on our mobile devices (cellular phone, PDA notebook, etc). But the limited available bandwidth of mobile communication network prohibits transmitting high-qualify AV contents. In addition, most bandwidth is assigned to transmit video contents. In this paper, we design a novel and simple method for reproducing high frequency components. The spectrum of high frequency components, which are lost by down-sampling, are modeled by the energy rate with low frequency band in Bark scale, and these values are multiplexed with conventional coded bitstream. At the decoder side, the high frequency components are reconstructed by duplicating with low frequency band spectrum at a rate of decoded energy rates. As a result of segmental SNR and MOS test, we convinced that our proposed method enhances the subjective sound quality only 10%∼20% additional bits. In addition, this proposed method can apply all kinds of frequency domain audio compression algorithms, such as MPEG-1/2, AAC, AC-3, and etc.