• Journal of Communications and Networks
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• v.13 no.3
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• pp.277-285
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• 2011

Real-time multimedia streaming over the Internet is rapidly increasing with the popularity of user-created contents, Web 2.0 trends, and P2P (peer-to-peer) delivery support. While many homes today are broadband-enabled, the quality of experience (QoE) of a user is still limited due to frequent interruption of media playout. The vulnerability of TCP (transmission control protocol), the popular transport-layer protocol for streaming in practice, to the packet losses, retransmissions, and timeouts makes it hard to deliver a timely and persistent flow of packets for online multimedia contents. This paper presents TCP-real-time online multimedia environment (ROME), a novel transport-layer framework that allows the establishment and coordination of multiple many-to-one TCP connections. Between one client with multiple home addresses and multiple co-located or distributed servers, TCP-ROME increases the total throughput by aggregating the resources of multiple TCP connections. It also overcomes the bandwidth fluctuations of network bottlenecks by dynamically coordinating the streams of contents from multiple servers and by adapting the streaming rate of all connections to match the bandwidth requirement of the target video.

• Progress in Superconductivity
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• v.4 no.1
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• pp.53-58
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• 2002

Noise from electronic instrumentation is invariably present in biomedical signals, although the art of instrumentation design is such that this noise source may be negligible. And sometimes signals of interest are contaminated or degraded by signals of similar type from another source. Biomedical signals are omni-presently contaminated by these background noises that span nearly all frequency bandwidths. In the magneto-cardiogram (MCG), several digital filters have been designed for the elimination of the power-line interference, broadband white noise, surrounding magnetic noise, and baseline wondering. In addition to the introduced FIR filter, notch, adaptive filter using the least mean square (LMS) algorithm, and recurrent neural network (RNN) filter, a new filtering method for effective noise canceling in MCG signals is proposed in this paper, which is realized by the wavelet packets. The experimental results show that the proposed filter using wavelet packet performs efficiently with respect to noise rejection. To verify this, two characteristics were analyzed and compared with LMS adaptive filter, SNR of filtered signal and attractor pattern using the nonlinear dynamics.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.5
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• pp.691-708
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• 2010

An important issue of supporting multi-users with diverse quality-of-service (QoS) requirements over wireless networks is how to optimize the systematic scheduling by intelligently utilizing the available network resource while, at the same time, to meet each communication service QoS requirement. In this work, we study the problem of a variety of communication services over multi-media heterogeneous cognitive OFDM system. We first divide the communication services into two parts. Multimedia applications such as broadband voice transmission and real-time video streaming are very delay-sensitive (DS) and need guaranteed throughput. On the other side, services like file transmission and email service are relatively delay tolerant (DT) so varying-rate transmission is acceptable. Then, we formulate the scheduling as a convex optimization problem, and propose low complexity distributed solutions by jointly considering channel assignment, bit allocation, and power allocation. Unlike prior works that do not care computational complexity. Furthermore, we propose the FAASA (Fairness Assured Adaptive Sub-carrier Allocation) algorithm for both DS and DT users, which is a dynamic sub-carrier allocation algorithm in order to maximize throughput while taking into account fairness. We provide extensive simulation results which demonstrate the effectiveness of our proposed schemes.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.10a
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• pp.200-218
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• 2004

Online game business has emerged as the most lucrative entertainment industry, with over 10 million players in South Korea. The popularity of online games can be attributed to the availability of broadband network and the presence of numerous PC Bangs and around the country, which have pushed online games into the mainstream entertainment culture. The age distribution of online game players is expanding and a variety of new games are under development to target certain age groups. While the interactive entertainment market continues to expand, with many new online game publishers entering the market, relatively little is known about which factors influence online game players' behavioral intentions to play continuously in this area. It appears that in this extremely attractive and growing services segment, academics, as well as practitioners, would benefit from investigating the relationships among the players' loyalty, interactivity, the sense of presence and the impacts of several other key game-related constructs. Several types of interaction in on-line games and their relationship with the flow construct are investigated, and the resulting conceptual model is proposed. Based on data collected from online questionnaire survey, the validity of the simultaneous equation model has been tested and interesting conclusions have been developed concerning the relationships between the players' loyalty to the sense of presence flow, satisfaction and interactions. Other interesting results concerning game development strategy are also provided.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.29
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• pp.173-196
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• 2006

Online game business has emerged as the most lucrative entertainment industry, with over 10 million players in South Korea and over 30 million in Japan in 2005. The popularity of online games can be attributed to the availability of broadband network, pushing online games into the mainstream entertainment culture. The age distribution of online game players is expanding and a variety of new games are under development to target certain age groups. While the interactive entertainment market continues to expand, with many new online game publishers entering the Japan, relatively little is known about which factors influence online game players' behavioral intentions to play continuously in this area. This study investigates major factors which influence the acceptance of online game services based on the theoretical backgrounds of the technology acceptance model(TAM) and the flow theory. This paper extended the Davis' TAM model by including the flow concept as another major factor toward the intention to play online game. Based on data collected from online questionnaire survey, we show that the proposed model provides an adequate fit to the data, and that the flow experience is another important factor influencing the intention to play online game, as well as the perceived ease of use.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.52.1-52.1
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• 2014

Radio pulsars are highly magnetized, rapidly rotating neutron stars that emit synchrotron radiation along the magnetic axes at their spin frequencies. Traditionally, pulsar observations have been done at low frequencies (MHz up to a few GHz), since radio pulsar spectrum is known to a power-law with a steep negative spectral index. More recently, high-frequency pulsar observations (several GHz and above) have been made as a broadband spectrometer and fast computers became available. High-frequency pulsar observations will provide information on radio emission mechanism of pulsars in the vicinity of the neutron star surface. There is also huge interest from gravitational-wave and astrophysics community to find a pulsar in the center of our Galaxy. The Korean VLBI Network has three 21-m single dishes in the Korean peninsula. Using KVN's lowest observational frequency of 22-GHz, we performed test observations with the KVN targeting a few selected known, bright pulsars. In addition, we have been developing pulsar pipelines that can be utilized with a VLBI facility using Mark-V. We present a brief introduction of radio pulsars and show data obtained with the KVN.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.2
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• pp.279-287
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• 2001

In this paper, we discuss the scale of subjective speech quality measurement over VoIP(Voice over IP) network which is a component of broadband networks. Objective parameters of multimedia services like PSNR or jitter can easily measured and defined, but these factors are not easily meet the user's perceptual recognition. We suggest the speech quality measurement scale through the subjective measurement for end-to-end speech quality composed of sender-side quality, transmission quality, receiver-side quality, which provide the degree of correctness of representation of speaker, the degree of impairment caused by various factors, the degree of recognition of processed speech, respectively. Also, we examined the proposed method and verify it's availability.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.3
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• pp.327-331
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• 2010

The 21.4-22.0GHz frequency band is used to broadcast satellite services in Region 1 and Region 3 in frequency distribution area. The use of this frequency band is according to the provision of the resolution 525 of WRC-03, this frequency band broadcasting service system transmits broadband radio-frequency signals. The trend of the Satellite launching plans for an using this frequency band is growing in worldwide. This frequency band requires fairly more transmit power than the Ku-band because of the rain attenuation of this frequency band is very extreme. An appropriable sharing criteria is required for this broadcast service to be operational.

• Information and Communications Magazine
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• v.21 no.8
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• pp.88-98
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• 2004

본 고는 통신의 진화 방향인 통합(convergence)의 추세를 나타낸다. 통합은 서비스, 네트워크, 비즈니스 등의 통합으로 실현되고 있다. 통합 서비스를 위한 기본 인프라인 광대역통합망(Broadband convergence Network)의 개념, 서비스 특징 및 발전방향 등을 기술한다. 광대역 통합망은 유무선 통합, 통신/방송 융합, 음성 및 데이터의 통합을 위해 필요한 네트워크를 서비스 계층, 제어 계층, 전달망 계층, 접속 계층, 유비쿼터스 접속 및 가입자 단말 계층으로 구분한다. BcN은 사용자가 원하는 품질과 보안의 정도에 따라 차별화된 광대역 멀티미디어 서비스제공 및 관리가 가능한 네트워크이다. 이러한 BcN진화를 위한 무선 네트워크 관점의 All-IP진화 방향을 나타낸다. 먼저, 무선 네트워크에서의 광대역 멀티미디어 서비스의 특징 및 종류, 이를 위한 광대역 통합망의 특징을 살펴본다. 그리고 향후 BcN으로의 무선 네트워크의 진화 방향을 나타낸다. BcN의 무선 네트워크는 다양한 광대역 멀티미디어 서비스를 제공하기에 적합한 이동성 및 광대역 엑세스가 가능한 시스템이 추가될 전망이다. 마지막으로, 향후 통신 서비스의 진화 방향인 유비쿼터스 서비스를 위해 필요한 유비쿼터스 네트워크를 전망한다. 미래의 유비쿼터스 네트워크를 위한 지능형 플랫폼, 통합 단말 등 기술적 요구사항들과 진화방향을 나타낸다.

• The Journal of Information Technology
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• v.9 no.4
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• pp.57-63
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• 2006

The intelligent elder brother groove network robot service the new broadband presence line is conversionce application service. Robot control data transmission hazard UDP packet of the remote control data which stands duplication necessary to transmit. TCP the error ratio to be high qualitative recording transmission pattern it of the transmission unit and is irregular the distance is distant to show and also the transmission lag is visible increases. The recording packet drop whose UDP degree error ratio will be high is frequent and does not arrive packet little by little increases is a possibility of knowing in the transmission unit. The technique which it proposes with traffic pattern of the transmission unit is visible the transfer characteristic of the same shape from 1% packet error ratio degree. The effective transmission technique of the robot control data which puts a base in UDP protocols was proposed from the present paper. Following research it leads and it follows the duplication transmission number of time in error rate of radio link and it was thought all that controls petty the research of the mechanism which progresses is necessary.