• Journal of Broadcast Engineering
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• v.4 no.1
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• pp.12-21
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• 1999

Without a question. the most significant new medium for transmitting information is the Internet. Unfortunately. the multimedia elements that enrich our titles are extremely bulky. While the Internet hype is available in unlimited supply. Internet bandwidth and functionality of web browser are not making the net quite hospitable to multimedia data formats. In this thesis. for smoother and better communications over the net. a study is done on still image compression techniques. based on wavelet transform which is selected on MPEG-4 as a still image compression standard and a strong candidate for the JPEG-2000 standard. For Internet service. the study of plug-in programming and ActiveX control is implemented to enrich the functionality of web browser. As a result. the proposed still image service gives better image quality than current standard JPEG and does not yield to the common blocking artifacts.

• The Journal of the Acoustical Society of Korea
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• v.32 no.5
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• pp.393-401
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• 2013

In this paper, a $48{\times}64$ channel 2D array ultrasonic transducer with piezoelectric single crystals was designed, fabricated, and evaluated. Structure of the transducer was chosen to facilitate the electric connection on the planar array, and then components were fabricated in accordance with the structure. Detailed structure of the transducer was designed through finite element analyses. In order to improve the performance of the transducer, the crosstalk between adjacent elements was reduced through the control of kerf width and material, and the target frequency bandwidth was achieved through optimal design of the thickness of the single crystal and matching layers. After fabricating a prototype of the transducer according to the design and measuring its characteristics, the results were compared with those of finite element analyses to evaluate the performance of the developed transducer.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.151-159
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• 2012

In this paper, we propose a new peer grouping scheme to consider locality among peers using TTL values in P2P-based IPTV systems. This scheme can select neighbor peers to minimize the number of intermediate routers between each pair of peers. Thus, it can save the network bandwidth as much as the amount of data that the reduced number of routers should transmit In addition, we have conducted various simulation experiments to show that our proposed TTL-based peer grouping scheme can outperform the conventional RTT-based grouping scheme. The experimental results show that our proposed scheme can reduce the jitter ratio as well as the number of data and control packets that all routers should transmit.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.900-905
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• 2009

A common drain feedback CMOS wideband LNA with current bleeding and input inductive series-peaking techniques is presented in this paper. DC coupling is adopted between cascode and feedback amplifiers, so that the gain and NF of the LNA can be dynamically controlled by adjusting the bleeding current. The fabricated LNA shows the bandwidth of 2.5 GHz. The high gain mode shows 17.5 dB gain with $1.7{\sim}2.8\;dB$ NF and consumes 27 mW power and the low gain mode has 14 dB gain with $2.7{\sim}4.0\;dB$ NF and dissipates 1.8 mW from 1.8 V supply.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.925-933
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• 2003

Network is expected to be developed into optical Internet network collected IP layer and optical layer, but GMPLS is risen at the transitional evolution stage because of the present technology level. GMPLS that MPLS is extended and generalized is able to support not only the packet switching device but also the devices which perform switching in time, wavelength, and space domain. To implement the common control plane to these various switching types, GMPLS extends the existing MPLS signaling and routing protocol. In this paper, we describe the overview of GMPLS technology, and then we will refer to the OSPF(Open Shortest Path First), which was used to exchange the status information of link, as the plan of routing extension to exchange the information of various link type, bandwidth, link protection type etc. And also, we describe the definition of new protocol, so called, LMP that is a signaling protocol for solving complex problem which manages hundreds and thousands of links between two nodes. And we will examine and analyze the plan of signaling protocol extension to apply signaling protocol RSVP-TE(Resource Reservation Protocol) for traffic engineering in MPLS to network, and the message objects and formats associated with modified RSVP.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.6
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• pp.41-46
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• 2019

In this paper, it is necessary to study the bandwidth and network system for efficient image transmission in the current era of drone imaging, and to design routing protocols to round out and cluster two or more multi-drones. First, we want to construct an ad hoc network to control the multidrone. Several studies are underway for the clustering of drones. The aircraft ad hoc network (FANET) is an important foundation for this research. A number of routing protocols have been proposed to design a FANET, and these routing protocols show different performances in various situations and environments. The routing protocol used to design the FANET is tested using the routing protocol used in the existing mobile ad hoc network (MANET). Therefore, we will use MANET to simulate the routing protocol to be used in the FANET, helping to select the optimal routing protocol for future FANET design. Finally, this paper describes the routing protocols that are mainly used in MANET and suitable for FANET, and the performance comparison of routing protocols, which are mainly used in FANET design.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.4
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• pp.828-834
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• 2009

To get a better profit, standalone mobile game market shifts network-based mobile game. Currently, most of the game platform are separated into mobile to mobile, desktop to desktop, and console to console. Multi platform network game has a diverse problems including consistency control, object management technique, and bandwidth inconsistency. n this paper, we will introduce a multi-platform arcade game "Push-Push", which is played on desktop to mobile environment. The game guarantees realtime play between heterogeneous machine users and game item sharing between two platforms. e will focus n the issues of the 3rd generation multi platform games and propose some techniques or solving these problems. Our server database is implemented on MS SQL database, also the desktop programming tool is Visual Basic, and WIPI(Wireless Internet Platform or Interoperability) as a mobile platform.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.5C
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• pp.445-453
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• 2002

We propose a cell-multiplexing scheme for the real-time communication service in ATM network and a new service discipline guarantee end-to-end delay based on pseudo-isochronous cell switching. The proposed scheme consists of two level frame hierarchy, upper and lower frame, which is used to assign the bandwidth and to guarantee the requested delay bound, respectively. Since the proposed algorithm employs two level frame hierarchy, it can overcome the coupling problem which is inherent to the framing strategy. The proposed scheme consists of two components, traffic controller and scheduller, as the imput traffic description model and regulates the input traffic specification. The function of the traffic controller is to shape real-time traffic to have the same input pattern at every switch along the path. The end-to-end delay is bounded by the scheduller which can limit the delay variation without using per-session jitter controllers, and therefore it can decrease the required buffer size. The proposed algorithm can support the QoS's of non-real time traffic as well as those of real time traffic

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.10
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• pp.2219-2235
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• 1997

The endpoints and exchanges involved in a call can establish heterogeneous connection each other according to required bandwidth and bearer availability in multimedia communication. and as participating users are increased, call setup delay must not be exceedingly increased. In this paepr, we propose DMMSP(distributed multiparty multiconnection signaling protocol) which can support heterogeneous connections and multimedia communications. DMMSP gets over a limitation of existing B-ISDN protocol and provides signaling capabilities to support various kinds of conncetions, and each endpint can setup individual connection with bearer availability. Moreover since DMMSP separatively performs call processing in distributed scheme, call setup delay can be minimized. We present call control procedures which can be applied to existing B-ISDN protocol and DMMSP respectively. We take multiparty multimedia conference call as an example thta is applied to the existing B-ISDN protocol and DMMSP, and compare and quantitatively analyze each procedures.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11A
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• pp.1173-1181
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• 2007

A number of routing algorithms have been studied for wireless mobile ad-hoc network. Among them, the AODV routing algorithm with on-demand method periodically transmits hello message and monitors link state during data transmission in order to maintain routing paths. When a path is disconnected, a node that senses it transmits a RERR packet to the transmitting node or transmits a RREQ locally so that the path could be repaired. With that, the control packet such as a RREQ is broadcast, which causes the consumption of bandwidth and incurs data latency. This paper proposes a LRRLBP algorithm that locally repairs a path by predicting link state before disconnecting the path based on the AODV routing protocol for solving such problems. Intensive simulations with the results using NS-2 simulator are shown for verifying the proposed protocol.