• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2006.05a
• /
• pp.981-985
• /
• 2006

Wibro is stand for Wireless Broadband Internet called as Portable Internet, Wireless Broadband Internet or Wireless High-Speed Internet. This provides hish-speed internet service anytime, anywhere, from anyone and device with seamless mobility and the band is located between Mobile phone and wireless LAN. Wibro service should support handover to maintain connection continuously in movement because the service is based on If system which is different from cellular system. Current Mitre Mobility system and general Mobile If system has got a problem of delayed speed and lost packets during handover. IETF protocol has been proposed for minimizing this problem and its standardization is under process, mainly focused on Mip4, Mip6 and Mipshop WG. This article studies and analyzes an effective method of minimizing handover delay to improve the problem of WiBro system and its revitalization & outlook.

• Journal of the Korean Professional Engineers Association
• /
• v.33 no.4
• /
• pp.48-53
• /
• 2000

To be survived and prosperous in this rigorous competition era for the nation with insufficient natural resources like us, we must create idea for additive products no matter small or large scale utilizing our knowledge. This is to show a small example of value creation in connection with ADSL(Asymmetric Digital Subscriber Line) POTS Splitter from developing to successful commercializing, which the ADSL system is booming up these days for high speed Internet connectivity.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.8
• /
• pp.10-17
• /
• 2015

A satellite communication system is one of viable solutions for Internet applications running in wide areas. However, the performance of TCP can be seriously degraded in the satellite networks due to long round-trip time (RTT) and high bit error rate (BER) over satellite links. Therefore, a performance enhancing proxy(PEP) based TCP splitting connection scheme is used in the satellite link to improve the TCP performance. In this paper, we implement PEP testbed and conduct experiment to evaluate the performance of TCP splitting connection by comparing with high-speed TCP solutions in various environments. In our experimental environment, we consider multiple connections, high packet loss, and limited bandwidth. The experiment results show that PEP improves the TCP throughput than high-speed TCP variants in various environments. However, there is no improvement of the TCP throughput with the limited bandwidth because there is packet loss caused by both the congestion and the channel error.

• The Journal of the Convergence on Culture Technology
• /
• v.5 no.3
• /
• pp.333-338
• /
• 2019

Cultural contents are the most important factor in high speed and high quality data communication. High-quality content includes VR and AR technology, and a variety of high-quality content can be streamed over wireless mobile phones via smartphones. In addition, network and wired/wireless communication are inevitably required in an Internet of Things (IoT) environment in which things are connected to a wireless Internet. IoT is used in various network technologies such as 4G, 5G mobile communication, WIFI wireless LAN, Bluetooth and so on. It is a technology that can use the connection between things anytime, anywhere, and can be achieved in a wireless mobile communication environment. Therefore, in this paper, we study data error compensation estimation method which can reduce data error based on mobile communication channel environment analysis so that high quality contents can be serviced even in high speed mobile environment.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.10
• /
• pp.4015-4033
• /
• 2015

The future mobile networks consist of hyper-dense heterogeneous and small cell networks of same or different radio access technologies (RAT). Integrating mobile networks of different RATs to provide seamless and smooth mobility service will be the target of future mobile converged network. Generally, handover from high-speed networks to low-speed networks faces many challenges from application perspective, such as abrupt bandwidth variation, packet loss, round trip time variation, connection disruption, and transmission blackout. Existing inter-RAT handover solutions cannot solve all the problems at the same time. Based on the high-layer convergence sublayer design, a new receiver-aided soft inter-RAT handover is proposed. This soft handover scheme takes advantage of multihoming ability of multi-mode mobile station (MS) to smooth handover procedure. In addition, handover procedure is seamless and applicable to frequent handover scenarios. The simulation results conducted in UMTS-WiMAX converged network scenario show that: in case of TCP traffics for handover from WiMAX to UMTS, not only handover latency and packet loss are eliminated completely, but also abrupt bandwidth/wireless RTT variation is smoothed. These delightful features make this soft handover scheme be a reasonable candidate of mobility management for future mobile converged networks.

• Journal of the Korea Safety Management & Science
• /
• v.6 no.3
• /
• pp.109-120
• /
• 2004

As an information-oriented era arrives, an environmental change of Internet marketing is going with high speed and such open door around the countries is providing worldwide companies with a new business opportunity. Now, Internet is a new communication tool for global network and is emerging as a new e-commerce market. Also, this trend is having an effect upon online site that sell crafts. Hence, this study aims to select artshop, which simultaneously operate off line and online while sell crafts, to research the present status, and analyze the problems to suggest the activation plans for effective Internet commerce. Accordingly, this study suggested six models for the settlement of these problem s and the activation plans as following: offer of the various works and the contents, security of price competition, reinforcement of marketing, establishment of brand recognition, management of customers and settlement of payment ways etc. The commerce of crafts in the artshop is only early stage today, but it is expected to grow into an universal connection way of information and buying which transcend space and to be briskly used for securing the competition of crafts in 21century.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.6 no.5
• /
• pp.446-452
• /
• 2005

As the name means, the WiBro is mobile service so that radio internet connection may be possible with high transmission speed using various terminal. Because WiBro is choosing suitable All-lP network architecture in internet service offer, structure of network is simple and the various supplementary service offer is available. This paper presented mobility model of terminal and proposed efficient way to improve existent way that transfer efficiency drops by data padding and analyze the performance by simulation.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.6
• /
• pp.2480-2496
• /
• 2020

Considering that high-dose X-ray radiation during CT scans may bring potential risks to patients, in the medical imaging industry there has been increasing emphasis on low-dose CT. Due to complex statistical characteristics of noise found in low-dose CT images, many traditional methods are difficult to preserve structural details effectively while suppressing noise and artifacts. Inspired by the deep learning techniques, we propose a densely connected residual network (DCRN) for low-dose CT image noise cancelation, which combines the ideas of dense connection with residual learning. On one hand, dense connection maximizes information flow between layers in the network, which is beneficial to maintain structural details when denoising images. On the other hand, residual learning paired with batch normalization would allow for decreased training speed and better noise reduction performance in images. The experiments are performed on the 100 CT images selected from a public medical dataset-TCIA(The Cancer Imaging Archive). Compared with the other three competitive denoising algorithms, both subjective visual effect and objective evaluation indexes which include PSNR, RMSE, MAE and SSIM show that the proposed network can improve LDCT images quality more effectively while maintaining a low computational cost. In the objective evaluation indexes, the highest PSNR 33.67, RMSE 5.659, MAE 1.965 and SSIM 0.9434 are achieved by the proposed method. Especially for RMSE, compare with the best performing algorithm in the comparison algorithms, the proposed network increases it by 7 percentage points.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.4
• /
• pp.753-757
• /
• 2005

Wireless LAN was developed by alternative of LAN and because establishment was easy, have used into special field and special expenditure. Recently, Standard and a technology developed by leaps and bounds. Present is used into purpose of the Building to Building or wide connection etc. and relay of the high speed Internet and usage of picture communication that require multimedia band width. Specially, campus wireless LAM is thought that must secure radius $100\;\~\;200\;m$ dimension at the minimum 10Mbps speed as Internet transit trunk. But, there is difference as degressive here. In this paper, wireless LAN measured for effectiveness proof as Internet transit trunk in actuality utilization environment. Proved that should compose IEEE802.11b as AP more than minimum 3 when compose network to base as measuring result. Hereafter, there is the purpose that achieve performance evaluation of wireless UM in marine environment.

• The Journal of Korea Robotics Society
• /
• v.1 no.2
• /
• pp.158-162
• /
• 2006

This paper presents a speaker recognition system intended for use in human-robot interaction. The proposed speaker recognition system can achieve significantly high performance in the Ubiquitous Robot Companion (URC) environment. The URC concept is a scenario in which a robot is connected to a server through a broadband connection allowing functions to be performed on the server side, thereby minimizing the stand-alone function significantly and reducing the robot client cost. Instead of giving a robot (client) on-board cognitive capabilities, the sensing and processing work are outsourced to a central computer (server) connected to the high-speed Internet, with only the moving capability provided by the robot. Our aim is to enhance human-robot interaction by increasing the performance of speaker recognition with multiple microphones on the robot side in adverse distant-talking environments. Our speaker recognizer provides the URC project with a basic interface for human-robot interaction.