• Journal of Broadcast Engineering
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• v.25 no.5
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• pp.655-664
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• 2020

Free viewpoint image synthesis technology is one of the important technologies in the MPEG-I (Immersive) standard. RVS (Reference View Synthesizer) developed by MPEG-I and in use in MPEG group is a DIBR (Depth Information-Based Rendering) program that generates an image at a virtual (intermediate) viewpoint from multiple viewpoints' inputs. RVS uses the mesh surface method based on computer graphics, and outperforms the pixel-based ones by 2.5dB or more compared to the previous pixel method. Even though its OpenGL version provides 10 times speed up over the non OpenGL based one, it still shows a non-real-time processing speed, i.e., 0.75 fps on the two 2k resolution input images. In this paper, we analyze the internal of RVS implementation and modify its structure, achieving 34 times speed up, therefore, real-time performance (22-26 fps), through the 3 key improvements: 1) the reuse of OpenGL buffers and texture objects 2) the parallelization of file I/O and OpenGL execution 3) the parallelization of GPU shader program and buffer transfer.

• Journal of KIISE:Computing Practices and Letters
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• v.11 no.1
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• pp.26-35
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• 2005

Generally, we employ FSMs for the design of controllers in digital systems. FSMs are Implemented with state diagrams generated from control flow. With HDL, we design and verify FSMs based on state diagrams. As the number of states in the system increases, the verification or modification processes become complicated, error prone and time consuming. In this paper, we propose a control flow oriented hardware description language at the register transfer level called Cycle-C. Cycle-C describes FSMs with timing information and control How intensive algorithms. The Cycle-C description is automatically converted into FSMs in the form of synthesizable RTL VHDL. In experiments, we design FSMs for control intensive interface circuits. There is little area difference between Cycle-C design and manual design. In addition, Cycle-C design needs only 10~50% of the number lines of manual RTL VHDL designs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.130-140
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• 2010

SIP (Session Initiation Protocol) is a signaling protocol to provide IP-based VoIP (Voice over IP) service. However, many security vulnerabilities exist as the SIP protocol utilizes the existing IP based network. The SIP Malformed message attacks may cause malfunction on VoIP services by changing the transmitted SIP header information. Additionally, there are several threats such that an attacker can extract personal information on SIP client system by inserting malicious code into SIP header. Therefore, the alternative measures should be required. In this study, we analyzed the existing research on the SIP anomaly message detection mechanism against SIP attack. And then, we proposed a Co-occurrence based SIP packet analysis mechanism, which has been used on language processing techniques. We proposed a association rule generation and an attack detection technique by using the actual SIP session state. Experimental results showed that the average detection rate was 87% on SIP attacks in case of using the proposed technique.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6B
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• pp.483-488
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• 2012

With the fast growing data traffic, the performance of the convergent overlay network environment under the cognitive networking environment is crucial for the implementation of the efficient network structure. In order to achieve high capacity and reliable link quality in wireless communication of the overlay convergent networks with the cognitive networking based on the advanced capability of the mobile terminal, a Distributed Wireless Communication System (DWCS) can provide the capability of ambient-aware dual cell system's operation. This paper has considered virtual cell: the Dual Virtual Cell (DVC), and also proposes DVC employment strategy based on DWCS network. One is the Active Virtual Cell which exists for user's actual data traffic and the other is the Candidate Virtual Cell which contains a set of candidate antennas to protect user's link quality from performance degradation or interruption. The considered system constructs DVC by using cognitive ability of finding useful virtual signals. Also, for multi-user high-rate data transmission, the DWCS system exploits Space-Time Trellis Codes. The effects of changing environments on the system performance has been investigated thereafter.

• Journal of Internet Computing and Services
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• v.3 no.1
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• pp.61-69
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• 2002

Big-bang growth of Internet and World Wide Web is supplying much information and resources to network. However, use of internet resources is receiving many limitations by bandwidth for most users. But, through Applet way, can solve degradation problem that follow on static side and bandwidth of CGI that HTML has. Mobile Agent starts in user's computer to accomplish user's specification purpose and achieves work rooving network. Because code that can perform so is transmitted, and is achieved in network through network, important problem happens to mobile code's security naturally. In computing environment that this research uses this Mobile Agent way that can protect host and agent groping report, describe problem that happen composing Mobile Agent relationship concept and Mobile Agent, and do so that may present method that is studying to solve these problem, and use method that application is possible actually among presented method and design transfer agent's security system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.7
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• pp.98-105
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• 2005

In this paper, the decryption function of CCSDS telecommand of CTU EQM for the security of communications satellite was verified. In order to intensify the security level of DES CFB decryption algorithm applied to CTU EM, 3DES CFB decryption algorithm using three keys is implemented in the CTU EQM. As the decryption keys increased due to the 3DES algorithm, the keys and IV are stored in PROM memory, and used for the telecommand decryption by taking the keys and IVs corresponding to the selected key and IV indexes from the memory. The operation of the 3DES CFB is validated through the timing simulation of 3DES CFB algorithm, and then the 3DES CFB core implemented on the A54SX32 FPGA. The test environment for the telecommand decryption verification of the CTU EQM was built up. Through sending and decrypting the encrypted command, monitoring the opcodes, and confirming LED on/off by executing the opcodes, the 3DES CFB telecommand decryption function of the CTU EQM is verified.

• Journal of Broadcast Engineering
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• v.15 no.2
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• pp.304-312
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• 2010

This paper presents the design of alert message and message segmentation method for the Terrestrial DMB Automatic Emergency Alert Service Standard. This paper begins with the introduction of the standard and some background. The alert message contains the essential information of the alert. Structured information is represented as coded fields and the unstructured as short sentences. Design factors of each field are analyzed first. Next each field’s semantics and syntax are described. The message segmentation method is presented next. The previous study selected FIDC as the message delivery channel. However, in most cases, the size of the alert message exceeds the maximum size of FIG, which is the basic unit packet for the channel. The current T-DMB standard does not support the segmentation method for FIDC. To solve the problem, this paper proposes an elegant segmentation method that garantees reliable, flexible, and fast receiver characteristic. This paper concludes with some additional tasks that should be resolved before the full-time alert service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12B
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• pp.1728-1735
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• 2011

In this paper, satellite data link waveform is proposed which is based on the waveform of Link-16 but LDPC code is studied instead of CCSK code in order to be optimized to satellite nonlinear channel environment and transmission characteristics. And the DSM (Demux, Selective CH switch, and Mux) transponder structure is suggested which can remove all of the jamming signal out of the transmission signal band and convert uplink hopping frequency to desired ones of downlink. The results of BER and anti-jamming performance analysis shows that the required Eb/No and processing gain in the worst case partial band jammer of the proposed waveform are 2.5dB and 52dB respectively and the anti-jamming capacity improvement of DSM transponder is maximum 2dB.

• Journal of the Korea Society of Computer and Information
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• v.17 no.3
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• pp.41-50
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• 2012

In the monitoring system based on web service application, it is faced with the problems like code reproduction, difficult scalability and error recovery derived from the frequent change of data structure. So we propose a technique of monitoring system by DTD(Document Type Definition) automatic generation. This technique is to use dynamic server-side script to cope with the change of sensor data structure, generate the DTD dynamically. An it also adapt the AJAX(Asynchronous JavaScript and XML) for XML data parsing, it can support mass data transmission and exception processing for data loss and damage. This technique shows the result of recovery time is decreased about 44.8ms in case of temporary data failure by comparing to the conventional XML method.

• Journal of Digital Convergence
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• v.13 no.2
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• pp.177-183
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• 2015

Cross Site Scripting enables hackers to steal other user's information (such as cookie, session etc.) or to do abnormal functions automatically using vulnerability of web application. This attack patterns of Cross Site Scripting(XSS) can be divided into two types. One is Reflect XSS which can be executed in one request for HTTP and its reply, and the other is Stored XSS which attacks those many victim users whoever access to the page which accepted the payload transmitted. To correspond to these XSS attacks, some measures have been suggested. They are data validation for user input, output validation during HTML encoding procedures, and removal of possible risk injection point to prevent from trying to insert malicious code into web application. In this paper, the methods and procedures for these two types are explained and a penetration testing is done. With these suggestions, the attack by XSS could be understood and prepared by its countermeasures.