• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.6 s.312
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• pp.110-116
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• 2006

In this paper, we implement a speech recognition system to support ubiquitous sensor network application services such as switch control, authentication, etc. using wireless audio sensors. The proposed system is consist of the wireless audio sensor, the speech recognition algorithm using psychoacoustic model and LDPC(low density parity check) for correcting errors. The proposed speech recognition system is inserted in a HOST PC to use the sensor energy effectively mil to improve the accuracy of speech recognition, a FEC(Forward Error Correction) system is used. Also, we optimized the simulation coefficient and test environment to effectively remove the wireless channel noises and correcting wireless channel errors. As a result, when the distance between sensor and the source of voice is less then 1.0m FAR and FRR are 0.126% and 7.5% respectively.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.1
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• pp.89-100
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• 2000

Recently, studies on the mobile computing environments that enable mobile hosts to move while retaining its network connection are in progress. In these mobile computing environments, one of the necessary components is the distributed file system supporting mobile hosts, and there are several issues for the design and implementation of the shared file system. Among these issues, there are problems caused by network traffic on limited bandwidth of wireless media. Also, there are consistency maintenance issues that are caused by update-conflicts on the shared files in the distributed file system. In this paper, we propose TWB(Trickle Write-Back) scheme that utilizes weak connectivity for cache management of mobile clients. This scheme focuses on saving bandwidth, reducing waste of disk space, and reducing risks caused by disconnection. For such goals, this scheme lets mobile clients write back intermediate states periodically or on demand while delaying unnecessary write-backs. Meanwhile, this scheme is based on the existing distributed file system architecture and provides transparency.

• The KIPS Transactions:PartA
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• v.12A no.7 s.97
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• pp.583-588
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• 2005

To develop SoC program for embedded systems, a tool that can remotely debug from host system is needed. Because the existing remote debugging systems using GDB don't offer information of the SoC program execution in real-time, it is difficult to observe condition of the program execution, and also they have limited characteristics to tools and use costly adaptors. In this paper, a real-time tracking tool that can record SoC status on the nv each execution of the assigned instructions is introduced and an economical USB-JTAG adaptor is proposed. And it is shown that this tool can track the execution of a composed program in the target system based on PXA255 processor.

• The Journal of Korean Association of Computer Education
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• v.13 no.6
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• pp.91-98
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• 2010

NAC(Network Access Control) has been developed as a solution for the security of end-point user, to be a target computer of worm attack which does not use security patch of OS and install Anti-Virus, which spreads the viruses in the Intra-net. Currently the NAC products in market have a sufficient technology of pre-connect, but insufficient one of post-connect which detects the threats after the connect through regular authentication. Therefore NAC users have been suffered from Zero-day attacks and malware infection. In this paper, to solve the problems in the post-connect step we generate the normal behavior profiles using the traffic information of each host, host information through agent, information of open port and network configuration modification through network scanner addition to authentication of host and inspection of policy violation used before. Based on these we propose the system to detect the hosts infected malware.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.3
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• pp.263-274
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• 2010

Mutual exclusion that applied on existing systems was designed for static distributed systems. but now computing environments are going to mobile computing environments. Therefore a mutual exclusion algorithm in static distributed environments should be designed for new computing environments. So this paper proposes a mobile mutual exclusion algorithm to support the mutual exclusion of shared resources in mobile computer environments. Mobile computing resources as wireless hosts cause new issues because of their mobility and weakness and made mutual exclusion problem more complex than stationary distributed environments. So we proposed a new mobile token mutual exclusion algorithm with deadlock-free and starvation-free in mobile computing environments based on spanning tree topology and extend for mobile computing environments. The proposed algorithm minimizes message complexity in case of free hopping in cellular networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.10
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• pp.2373-2379
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• 2015

COMS(Communication, Ocean and Meteorological Satellite), the first Korean geostationary meteorological satellite, provides free meteorological information through HRIT/LRIT(High/Low Rate Information Transmission) service. This work presents the development of data receiver circuit that is essential to the implementation of a low-cost meteorological information receiver system. The data receiver circuit processes the data units according to the specification of physical layer and data link layer of HRIT/LRIT service. For this purpose, the circuit consists of a Viterbi decoder, a sync. word detector, a derandomizer, a Reed-Solomon decoder and so on. The circuit also supports PCI express interface to pass the information data on to the host PC. The circuit was implemented on an FPGA(field programmable gate array) and its function was verified through simulations and hardware implementation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1C
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• pp.90-95
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• 2002

Though the FTP(File Transfer Protocol) has been used widely and stable, It has the structural weakness that can't support current file transmissions so that we have to wait the completion of previous file transmission when try to transmit another file. If try to transmit multiple files concurrently using this FTP, It has to forking multiple FTP servers and clients in each user's PC and ISP's host machine it would result in the waist of memory, resource of network and the high workload of system. In order to solving previous problem, in this paper I have designed the new model of FTP which based on multi-thread and created NFTP(Next-Generation FTP)protocol so that may reduce the workload of system and support current file transmission effectively. I have implemented NFTP and also applied to real service, as a result It have provided reliable service by reducing the workload of system and saved the waiting time which would happened.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.8-14
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• 2016

When Open Source Projects are processed by multiple developers, the Version Control Systems, which control the different versions of the same file being used, is a very useful tool. On the other hand, because most of conventional VCS(SVN, Git, etc.) mainly control the history of the modifications of the source codes or documents, there is an inconvenience that each developer should modify the development environment whenever the development environment is modified. To overcome this inconvenience, this paper suggests a scheme of VC for OSP. The basic concept of the suggested scheme is that an image, including the development environment and controls, is created as a new version using the Docker, virtualization tool of the container method. To review the functional appropriateness of the suggested scheme, after establishing the Docker on the hosts that use the different OS( Ubuntu12.0.4, CentOS7), this study tested a VC that could control the different versions including the history of modifications of the development environment and evaluated them by a comparison with the conventional VCS. The results show that the suggested scheme is a convenient scheme of VC for the OSP.

• Journal of KIISE:Information Networking
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• v.29 no.6
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• pp.613-624
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• 2002

Within the past decade, TCP/IP network environment has been explosively widespread all over the world. As the internet and the WWW expand their boundaries, the network traffic caused by data transfers over the internet has also increased. In this paper, we present the design and implementation of a WebTraMAS (Web-based Traffic Monitoring and Analysis System) which can resolve the shortcomings of current management approaches, particularly on the network traffic monitoring and analysis. The WebTraMAS presented in this paper performs the network management activities based on the parameters related to the MIB-II of SNMP and the parameters related to the QoS such as network performance and fault. The proposed WebTraMAS, implemented using the WWW technology, is able for the network manager to manage the network easily and platform independently with the performance analysis of internet traffic.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6C
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• pp.651-657
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• 2006

This paper propose the technique for the execution authentication of digital signature with TTS(traceable trust server) to guarantee the safe execution of mobile agents. That is to say, it is focused on improving the processing speed of systems and the traffic of network which are problems in the existing studies. The digital signature is used to guarantee the efficient and safe execution and the integrity of mobile agents. The certificate of it is chained with synthesis function, cryptographic algorithm based on public key, and hash function. And white hosts can be protected against the threat of being used maliciously. Then, we prove the efficiency of system overhead and the traffic of network by the analysis. In case the certificate chain of a digital signature is used, the safe execution of mobile agents can be protected against attackers that wish to insert a newly created certificate after cutting off the chain after striking space key 2 times.