• Journal of Korea Multimedia Society
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• v.8 no.5
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• pp.707-741
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• 2005

In the multimedia streaming technology, the unicast method require additional cost by an increase traffic according to increase a number of users. The multicast method can solve this problem, but it don't have connection and control information of clients. Now, the most routers support only unicast. Also it has a problem with an exchange of service in other ISP. This paper proposes traffic agent system which is applied unicast and P2P(Peer to Peer) for distance video teaming to overcome this problem. The proposed system decrease the traffic of stream server by control agent, and cut down expenses of network. This system is tested under the distance video leaning using JMF and application software.

• Journal of Korea Multimedia Society
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• v.7 no.11
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• pp.1564-1570
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• 2004

Recently, The Analog TV has been being replaced by digital TV. This dues to the advantage of digital TV that sends data as well as audio/video stream to the receiver. But there are no standards or rules for processing the data. So, most companies or developers process the data in separate methods. This absence of standards or rules for processing the data causes many confusions and waste of time, money, man power. This Thesis proposes the solution of the problem not based on standardized respect but methodological respect. This solution is using XML in producing and playing the broadcasted multimedia contents and data. We believe that this solution saves much man power, time, money and increase reusability of expensive broadcasting contents.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.6
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• pp.863-872
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• 2002

Real-time(RT) object-oriented(00) distributed computing is a form of RT distributed computing realized with a distributed computer system structured in the form of an object network. Several approached proposed in recent years for extending the conventional object structuring scheme to suit RT applications, are briefly reviewed. Then the approach named the TMO(Time-triggered Message-triggered Object) structuring scheme was formulated with the goal of instigating a quantum productivity jump in the design of distributed time triggered simulation. The TMO scheme is intended to facilitate the pursuit of a new paradigm in designing distributed time triggered simulation which is to realize real-time computing with a common and general design style that does not alienate the main-stream computing industry and yet to allow system engineers to confidently produce certifiable distributed time triggered simulation for safety-critical applications. The TMO structuring scheme is a syntactically simple but semantically powerful extension of the conventional object structuring approached and as such, its support tools can be based on various well-established 00 programming languages such as C++ and on ubiquitous commercial RT operating system kernels. The Scheme enables a great reduction of the designers efforts in guaranteeing timely service capabilities of application systems.

• The KIPS Transactions:PartB
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• v.8B no.3
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• pp.261-268
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• 2001

연속형 미디어는 대용량이고 실시간으로 전송되어야 하므로 전송에 요구되는 네트워크 자원에 부하를 준다. 일반적으로 프락시는 자주 참조되는 객체를 캐슁하여 서버로의 네트워크 전송 대역폭을 줄이기 위한 기법으로 사용되고 있으나 기존의 연구들이 이미지나 텍스트 등의 비 실 시간성 객체 지향적으로 설계되어 실 시간성 객체의 서비스에는 적합하지 않다. 그러므로 본 논문에서는 패칭기법[10]을 사용한 프락시 관리 기법을 사용하여 연속형 스트림 서비스를 하는 스트림 서비스 기법을 제안한다. 제안한 기법에서는 프락시에 캐슁된 데이터의 양에 따라 스트림 전송 방식을 달리한다. 첫째, 요청된 객체 전체가 캐슁되어 있을 경우 프락시 만으로 서비스한다. 둘째, 요청된 객체가 전혀 캐슁되어 있지 않을 경우 후행 스트림들이 서버로부터 객체를 전송할 때 발생하는 초기 지연을 상쇄할 만큼의 데이터를 선반입한다. 셋째, 일부분만이 캐슁된 경우에는 해당 객체를 요청하는 스트림 사이에 존재하는 양만큼의 데이터를 프락시에 패칭하며 이 경우에는 사용자 노드는 두 개의 채널을 열어 하나는 프락시에 패칭된 데이터를 읽는데 사용하며 또 하나의 채널로는 서버로부터 나머지 부분을 읽어오는데 사용한다.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.6
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• pp.31-48
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• 2013

South Korea had encouraged farmers to breed bear to increase farmer's income since 1981. Currently farmers breed over thousand number of bears, however but the policy measures for breeding bears is expected to conflict the main stream of bear conservation due to South Korea belong to the member of CITES, which categorizes and manages bears under Wild Fauna and Flora Protection Act. Government needs to establish a special law containg the win-win relief strategy not only for farmers of breeding bears, but international corresponding policy. So, we have reviewed the domestic status and international trends on breeding bears, and suggest the alternative strategies of the policy such as a bear park, a bear village, use of species recovery center, use of a preservation organization. This policy should be accompanied with more detailed fact analysis, management agency, well equipped welfare facility and financial preparation for proper management of breeding bears against changing international trends on wildlife conservation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10A
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• pp.1020-1030
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• 2006

As the Terrestrial DMB(T-DMB) has been launched, service providers are focusing on finding a business model as well as preparing the variety of data services. So, the need for development of the CAS(Conditional Access system) is urgently required and its domestic standardization is also in progress. This Paper proposes design and implementation methods of an Ensemble Re-multiplexer and receiver platform for its verification that can be used for the CAS system in T-DMB. And, with transmitting ensemble stream scrambled by the proposed Ensemble Re-multiplexer, we verified their performance by do-scrambling and decoding according to scramble mode at the receiver platform.

• Information and Communications Magazine
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• v.16 no.10
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• pp.112-124
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• 1999

본 논문에서는 FTTC/VDSL (Fiber-to-the-Curb/Very High-speed Digital Subscriber Line) 전송시스템의 개발동향과 ANSI, ETSI, ITU등의 표준화 위원회에서 현재 진행중인 VDSL 시스템의 표준화 작업에 대해 기술하였다. 특히, POTS (Plain Old Telephone Service), BA-ISDA(Basic Access Integrated Services Digital Network), HDSL(High-rate Digital Subscriber Line), SDSL (Single-pair HDSL), ADSL(Asymmetric Digital Subscriber Line) 등의 다양한 xDSL (Digital Subscriber Line) 서비스들에서 발생하는 NEXT (Near-end Crosstalk)/FEXT (Far-end Crosstalk)와 같은 crosstalk를 최소화하기 위해 제안된 VDSL시스템의 주파수 대역과 PSD (Power Spectral Density) mask에 관해 설명하고, 순방향(down-stream) 채널과 역방향(upstream) 채널의 데이터 전송률이 대칭적인 VDSL전송시스템과 비대칭적인 VDSL 전송시스템 간의 주파수대역의 호환성 문제, RFI(Radio Frequency Interference) ingress/egress 문제의 해결 방안에 관해 기술하였다. 또한, 현재 VDSL Coalition과 VDSL Alliance 간에 논의 중인 VDSL 전송시스템의 변복조 방식에 관한 표준화 작업과정 및 순방향과 역방향에 할당될 band 개수에 따른 시스템 성능의 장단점 등에 관해 살펴보았다. 끝으로 현재 국내에서 개발되고 있는 FTTC/VDSL 전송시스템의 전체구조를 요약하고, 네트워크에서 가입자쪽으로 순방향 데이터 전송에 사용된 51.84 Mb/s 19-CAP (Carrierless Amplitude/Phase Modulation) 전송시스템과 가입자 댁내에서 네트워크 방향으로 역방향 데이터 전송에 사용된 1.62 Mb/s QPSK (Quadrature Phase Shift Keying) burst-mode TDMA (Time Division Multiple Access) 전송시스템 등의 동작 원리 및 구조를 기술하였다.

• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.6
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• pp.3-12
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• 2008

It is important to estimate accurate effective rainfall to analyse flood flow and long-term runoff for the rational planning, design, and management of water resource. The initial abstraction is also important to estimate effective rainfall. The Soil Conservation Service (SCS) has developed a procedure and it has been most commonly applied to estimate effective rainfall. But the SCS method still has weak points, because of unnatural assumptions such as antecedent moisture conditions and initial abstraction. The coefficient of initial abstraction(K) is depending on the soil moisture condition and antecedent rainfall. The maximum storage capacity of Umax which is calibrated by stream flow data in the proposed watershed was derived from the DAWAST(DAily WAtershed STreamflow) model. The values of K obtained from 69 storm events at the five watersheds are ranging from 0.133 to 0.365 and its mean value is 0.207. Effective rainfall could be estimated more reasonably by introducing new concept of initial abstraction. The equation of $K=0.076Sa^{0.255}$ was recommended instead of 0.2 and it could be applicable to the small-medium rural watersheds.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.187-190
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• 2006

In this paper, we describe a new 1/4 rate robust modulation techniques for Enhanced-x VSB system which is fully backward compatible with ATSC 8-VSB standard. 1/4 rate mode Enhanced-xVSB system provides broadcasters with a wide choice of trade-offs of data rate vs amount of robustness of enhanced data for pedestrian/mobile services. Lab test results of proposed Enhanced-xVSB 1/4 rate mode robust stream are a significantly improved multipath as well as AWGN reception performance for Enhanced-xVSB receiver. We suggest an Enhanced-xVSB terrestrial broadcasting system for ATSC HDTV and pedestrian/portable TV simultaneous broadcasting service providing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.10A
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• pp.1494-1500
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• 1999

In order to provide high speed multimedia data rate service, Multi-Code CDMA has been proposed which converts high speed serial data stream into N parallel low speed data streams with orthogonal PN codes for spreading. However this signal has multi level and causes interferences to be increased at the neighboring cell boundary in the reverse link. Therefore in order to solve the above mentioned problem, M/B-MC/CDMA, in which multi level signal is converted to binary level signal using M/B conversion, is proposed and the performance is compared with MC-CDMA.