• Journal of Internet Computing and Services
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• v.6 no.5
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• pp.133-141
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• 2005

In this paper, we designed about OFDM/QPSK image transmission system simulator embedded watermark in wireless channel environment. Channel environment used OFDM/QPSK still image transmission system considering AWGN, Multi-path fading. And, we analyzed effect of still image and watermark information in considered channel environment. Watermark information is coded by DM-SS (Direct Matric/Spread Spectrum) image watermarking scheme, Also, we used interleaving scheme for mitigating the degradation in watermarking data under wireless channel. As a results, we could know that PSNR of watermark image improved of about 1dB by 54.2371dB then apply interleaving in same multi-path fading environment.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.2
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• pp.81-91
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• 2008

In mobile wireless communications, there is a new approach that uses the lacking spectrum efficiently. A cognitive radio is a device that can changes its transmitter parameters based on interaction with the environment in which it operates. At present, the wireless communication standard for wireless device contains power-saving modes or energy efficient mechanisms which cuts off the power of transmitter and receiver for power-saving. However, in cognitive radio environment, every device has the Quiet Period for searching channel and existing energy-saving method is not appropriate to be adjust to cognitive radio environment. In this paper, we propose an energy-efficient MAC protocol of mobile device in cognitive radio environment and prove the improvement of proposed method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5496-5505
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• 2012

As the IT industry develops, the smart-phone technology and functions which are actively being studied at the moment greatly influence the entire living environment. With the smart-phone technology and functions, people's interest for the wireless LAN which can be used to get access to the Internet anytime anywhere is gradually increasing. However, since the malicious attacker can easily carry out hacking or approach the contents due to the characteristics of the wireless radio wave, the personal information with a high level of importance for data security is easily exposed due to Spoofing, Denial of Service attack and Man in the Middle attack. Therefore, the demand for security is gradually increasing. In this paper, the safe wireless network service environment is provided by supplementing the vulnerability in regard to Spoofing, Session Hijacking and Man in the Middle attack after executing the client's authentication process, the AP authentication process and the Mobile Agency authentication process with the client's information in the USIM, the AP information and the Mobile Agency information when the client uses the wireless Internet through the Mobile Agency AP access in the smart phone environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5A
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• pp.464-472
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• 2011

As wireless sensor networks are applied to various applications such as environment monitoring and disaster sensing system, there are increased needs for wireless communication in underground environment. Since the previous wireless communication technology using electromagnetic wave is not appropriate for the underground environment, a new alternative is required. Recently a magnetic field communication technology has been proposed and standardized as a domestic KS standard. In this paper, we analyze the media access control protocol of the KS standard by an analysis and a simulation study.

• Journal of Advanced Navigation Technology
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• v.16 no.1
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• pp.54-61
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• 2012

The WAVE specification, which for the Next-Generation ITS environment is a common title: IEEE 802.11p and IEEE P1609 specifications. These days, there are many activities for researching WAVE specification by release of the IEEE 802.11p specification. The difference between high-speed vehicle environment and the indoor environment, the wireless communication channel mode is that much more severe. Thus, the wireless communication system design, temperature, noise, multipath fading and can degrade the performance of the system points should be fully considered matters of. In this paper, we showed WAVE wireless communication system which based on IEEE 802.11p PHY/MAC design process, and also showed solving process many implementation problems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.9
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• pp.4510-4526
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• 2017

Most available methods of facial gender recognition work well under a constrained situation, but the performances of these methods have decreased significantly when they are implemented under unconstrained environments. In this paper, a method via low-rank and collaborative representation is proposed for facial gender recognition in the wild. Firstly, the low-rank decomposition is applied to the face image to minimize the negative effect caused by various corruptions and dynamical illuminations in an unconstrained environment. And, we employ the collaborative representation to be as the classifier, which using the much weaker $l_2-norm$ sparsity constraint to achieve similar classification results but with significantly lower complexity. The proposed method combines the low-rank and collaborative representation to an organic whole to solve the task of facial gender recognition under unconstrained environments. Extensive experiments on three benchmarks including AR, CAS-PERL and YouTube are conducted to show the effectiveness of the proposed method. Compared with several state-of-the-art algorithms, our method has overwhelming superiority in the aspects of accuracy and robustness.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.379-383
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• 2004

Mobile Internet has different platform cause interrupt activation of mobile internet because contents providers have each different development environment. To use of WIPI(Wireless Internet Platform for Interoperability) developer by KWISF(Korea Wireless Internet Standard Forum) founded to solve this problem guarantee independence of hardware and interpretation of mobile application. In this paper, we research method to activate WIPI which is standard platform to develop applications easily and efficiently in mobile environment and we implement WIPI application to show the excellent of WIPI in mobile development environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.1
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• pp.40-45
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• 2007

In this paper, aim to suggest the medical information wireless transmission system to provide the mobility of medical service by means of wireless area network which makes it possible, home or at a long range, to check and oversee the state of patients, and to can out a simulation. The proposed method converts medical information to digital data in an emergency and sends them to mobile terminals such as PDAs to make possible swift first aid. The simulation took advantage of the OFDM transmission method based on IEEE 802.1la in order to send reliable medical information in mobile wireless channel environment, and analyzed the system performance by applying convolution encoding to transmit reliable information in AWGN and 3-ray mobile multipath fading channel environment.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.2
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• pp.46-49
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• 2010

This paper has proposedfor wireless Ad-hoc networks with robust route maintenance schemes. The device feature Bluetooth and/or IEEE 802.11 network interfaces and communicate in a decentralized manner. The nodes have the responsibility of self-organizing so that the network is robust to the variations in network topology due to node mobility as well as the fluctuations of the signal quality in the wireless environment.

• Proceedings of the Korea Contents Association Conference
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• 2004.05a
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• pp.296-300
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• 2004

In this paper, we discuss about mobile Internet security. The past few years have seen unprecedented growth in the number of wireless user, applications, and network access technologies. Wireless Internet is similar to wired internet, but it has some constrained wireless environment. So many internet technologies for wireless are developing now