• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.10
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• pp.1903-1911
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• 2016

As interest in MANET is increasing nowadays, research upon an efficient MANET routing protocol is actively under way. A LQA(Link Qualty Aware)-AODV routing protocol to deal with frequent changes of topology and wireless link variations under tactical operating conditions is proposed in this paper. The suggested LQA-AODV takes into account the channel capacity of each hop during the route request process of the traditional AODV protocol. In detail, LQA-AODV adds a channel capacity cost value to the RREQ message format that occurs during the routing process of the existing AODV Routing Protocol causing the accumulated channel capacity cost values of each sections to be compared before establishing a route. To verify the performance of LQA-AODV, NS2.35 was utilized and the Link-Quality Model was applied in order to reflect the tactical wireless environment. The simulation compares and analyzes LQA-AODV and the existing AODV, showing a large improvement over the traditional AODV in regards to the Packet Delivery Ratio, and End-to-End Delay.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.763-765
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• 2015

The study is being conducted to ensure the transparency of research and development have identified the problems of the current system and improve the way out. Such a study about the subject that do not follow either outside the institutional system has a disadvantage compared to an unfulfilled. R & D in order to prevent the misuse and fraud enforcement shall detect abnormal transactions that occur from transactions between research institutions and credit card issuers in real time. In this paper, we propose a detection method for real-time transaction over. It is able to detect and respond fraudulent transactions that may occur in a variety of environments by adding the data obtained by the business rules to derive stopped making detection system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4A
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• pp.370-377
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• 2004

In this paper, we present an adaptive modulation technique for orthogonal frequency division multiplexing (OFDM) for broadband wireless communications. Also, using improved channel prediction, we enhance the performance of adaptive OFDM in high mobility environments. Adaptive modulation technique has been shown to achieve reliable high-rate data transmission over frequency-selective fading channel when OFDM is employed. This scheme requires the accurate channel information between two stations for a better performance. In an outdoor high mobility environment, most of adaptive OFDM systems have to be given the channel information transmitted from the receiver. Even if it is possible, there is some delay. Moreover, the channel impulse response between two stations is very rapidly varied. If the channel information is obsolete at the time of transmission, then poor system performance will result. In order to solve this problem, we propose adaptive OFDM with improved channel predictor. The proposed bit allocation algorithm has a lower complexity and the proposed scheme mitigates the effect of channel delay. Robust approach is less sensitive to outdated channel information. Performance results show that the proposed scheme can achieve considerable performance enhancement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1B
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• pp.27-34
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• 2010

As VoIP systems move to wireless environments with much higher average packet loss rates than wired networks, it becomes less possible for the network to assure a reasonable QoS. So, real-time quality monitoring for mobile VoIP applications is an important issue to be explored. In this paper, we explore perceptual quality dependency on two parameters: the burst loss rate and average burst length. Also, we propose a simple 'moving average' approach with $\alpha$ aiming to measure those parameters on real-time basis. In order to find how accurately the two parameters measured estimate the real perceptual quality, we compare actual measured PESQ scores with estimated value by matching the measured quality metric to the trained MOS table. Finally, we propose the quality-based accounting system, which can set obvious continuities between quality and billing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5C
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• pp.556-564
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• 2007

This paper proposes an efficient scheme to track a time variant channel induced by multi-path Rayleigh fading in mobile MIMO-OFDM systems with null sub-carriers. The proposed adaptive channel tracking scheme removes in the frequency domain the interfering signals of the other transmit (Tx) antennas by using a predicted channel frequency response before starting the channel estimation. Time domain channel estimation is then performed to reduce the additive white Gaussian noise (AWGN). The simulation results show that the proposed method is better than the conventional channel tracking method [3] in time varying channel environments. At a Doppler frequency of 300 Hz and bit error rates (BER) of 10-3, signal-to-noise power ratio (Eb/N0) gains of about 2.5 dB are achieved relative to the conventional channel tracking method [3]. At a Doppler frequency of 600 Hz, the performance difference between the proposed method and conventional one becomes much larger.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.3
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• pp.291-297
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• 2014

Due to the rapid increase in demand for transportation of human and freight in modern railway systems, the CBTC system has been proposed, which is the solution for improvement of the line capacity that has been limited by the conventional track circuit based train control system. In the CBTC system, higher reliability of the communication system should be guaranteed for the safety of passengers and trains. However, due to the inherent characteristics of the wireless channel environment, performance degradations are inevitable. The diversity techniques can increase the reliability of data transmission using multiple antennas. In this paper, we investigate the performance of the STBC in the railway channel environment. Rician fading model is used for the viaduct scenarios which take important roles in the railway system. Also, considered is the Doppler effect which is an important factor in the mobile communication system. Simulations are performed to analyze the performance of the STBC in various channel environments. Results show that the performance degradation due to the phase error in viaduct scenarios is independent of the diversity order but is affected by the constellation of the modulation.

• Anxiety and mood
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• v.12 no.1
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• pp.13-20
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• 2016

Objective : The purpose of this study was to verify the differences of expressed character strengths graded as per the Korean Strength Scale, based on the type of work. Methods : A total of 2,444 conglomerate workers were classified into two groups: 1,356 office workers and 1,088 production workers. The subjects were examined through a web or mobile application based on the Korean Strength Scale. The Korean Strength Scale consists of a total of four top entries and 25 sub-items with appropriate validity. Results : The difference in the average score of sum of character strengths between the two groups was not significant. In the office worker group, character strengths such as love of learning, creativity, perspective, curiosity, facilitation, judgment and faith had significantly high scores. On the other hands, modesty, hope, gratitude, sincerity, magnanimity and self-regulation were high in the production worker group. The results remained unchanged in additional analysis of covariants as sex, age and education level, except for self-regulation and faith. Conclusion : Our results suggest significant differences in the character strengths between the two types of work; however, the average of sum of character strength score remains unchanged. These results may help to understand differences between work environments and thus help to establish a positive foundation.

• Journal of Digital Convergence
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• v.11 no.10
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• pp.419-429
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• 2013

The Wireless sensor network(WSN) consisting of a large number of sensors aims to gather data in a variety of environments. The sensor nodes operate on battery of limited power. so, To extend network life time is major goals of research in the WSN. In this paper, we state the key point of a energy consumption with minimum&load balancing. The proposed protocol guarantee balance of number of cluster member nodes using the node memory threshold and optimization of distribution of cluster head using the optimized clustering method. The results show that the proposed protocol could support the load balancing and high energy efficiency by distributing the clusters with a reasonable number of member nodes. The simulation results show that our schme ensure longer life time in WSN as compare with existing schemes such as LEACH and CBLM.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.6
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• pp.65-72
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• 2009

This paper presents a vision based localization method for indoor mobile robots using the types of vertices from a monocular image. In the images captured from a camera of a robot, the types of vertices are determined by searching vertical edges and their branch edges with a geometric constraints. For obtaining correspondence between the comers of a 2-D map and the vertex of images, the type of vertices and geometrical constraints induced from a geometric analysis. The vertices are matched with the comers by a heuristic method using the type and position of the vertices and the comers. With the matched pairs, nonlinear equations derived from the perspective and rigid transformations are produced. The pose of the robot is computed by solving the equations using a least-squares optimization technique. Experimental results show that the proposed localization method is effective and applicable to the localization of indoor environments.

• Journal of Digital Contents Society
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• v.15 no.1
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• pp.69-76
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• 2014

In this study, by using the control technique of the user using augmented reality technology, to provide a game system touch-based. The augmented reality technology, can be advantageously used vehicle is easily recognized as a technique for synthesizing (images, video, text) object of the virtual image of the real world. Augmented reality technology has been studied to make the application in various fields. Studies of natural marker-based marker and base are underway, but there is no sense of incongruity in reality research natural marker-based and has been studied much. By using the augmented reality technology natural marker-based In this paper, we implemented a game system. The system also has the advantage that can be absorbed in the game by using the techniques of the interaction through a user's touch. Touch interface-based, are available as well as user environments, even in mobile devices such as smart-phone and touch pad.