• Journal of KIISE:Information Networking
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• v.30 no.3
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• pp.329-342
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• 2003

Most of the existing multicast routing protocols for ad-hoc networks do not take into account the efficiency of the protocol for the cases when there are large number of sources in the multicast group, resulting in either large overhead or poor data delivery ratio when the number of sources is large. In this paper, we propose a multicast routing protocol for ad-hoc networks, which particularly considers the scalability of the protocol in terms of the number of sources in the multicast groups. The proposed protocol designates a set of sources as the core sources. Each core source is a root of each tree that reaches all the destinations of the multicast group. The union of these trees constitutes the data delivery mesh, and each of the non-core sources finds the nearest core source in order to delegate its data delivery. For the efficient operation of the proposed protocol, it is important to have an appropriate number of core sources. Having too many of the core sources incurs excessive control and data packet overhead, whereas having too little of them results in a vulnerable and overloaded data delivery mesh. The data delivery mesh is optimally reconfigured through the periodic control message flooding from the core sources, whereas the connectivity of the mesh is maintained by a persistent local mesh recovery mechanism. The simulation results show that the proposed protocol achieves an efficient multicast communication with high data delivery ratio and low communication overhead compared with the other existing multicast routing protocols when there are multiple sources in the multicast group.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.130-133
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• 2002

As a society advances, an aging phenomenon and many diseases which did not exist in old times are happening. Especially, in case of the aged patient, because we cant know the time the condition of the patients health become worse, the study of the Tele-information system has been actively carried out by the necessity of a persistent observation. A ECG signal a kind of a vital signals has been widely used to the medical information system as an usual clinical diagnosis for the patients who possess heart diseases. BlueTooth is a close range wireless communication technology which uses a wireless frequency 2.4GHz and has a high trust and self - error correction technology according to a low power consumption quality and a high-speed frequency hopping. This makes get a high trust concerning a data transmission than an existing modem. In addition, though wireless modem is restricted by a minimal of a wireless terminal, It will be possible to coincide with the function of the portable with the low power consumption quality by using Bluetooth. And as the system on a chip of module progresses, the possibility of the small size is present According to this, Bluetooth module transmits the medical information, which is input from the outside among the operations that use the Bluetooth to the Bluetooth module that is connected the host PC. And the system that the host PC transmits the medical information from the connected Bluetooth module to the Internet has once embedded. this study let the host PC embedded in advance of the existing system and transmit the medical information by the addition of the Tcp/Ip protocol stark under all embedded environments to internet.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.10
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• pp.2181-2190
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• 1997

The synchronous stream cipher has the problem of synchronization loss by cycle slip. Synchronization loss make the state which sender and receiver can't communicate and it may make the receiving system disordered. To lessen the risk, we usually use a continuous resynchronization which achieve resynchronization at fixed timesteps by inserting synchronization pattern and session key. While we can get effectively resynchronizationby continuous resynchronization, there are some problems. In this paper, we proposed an adaptive resynchronization algorithm for cipher system using LAPB protocol. It is able to solve the problem of the continunous resynchronization.The proposed adaptive algorithm make resynchronization only in the case that the resynchronization is occurred by analyzing the address field of LAPB. It measure the receiving rate of the address field in the decesion duration. If the receiving rate is smaller than threshold value, it make resynchronization or not. By using adaptively resynchronization, it solves the problems of continunous resynchronization. When the proposed adaptive algorithm is applied to the synchronous stream cipher system which is used in X.25 packet network, it reduced the time for resynchronization by ten times. It means that 11.3% of total data for transmit is compressed.

• The Journal of the Korea Contents Association
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• v.8 no.10
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• pp.45-53
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• 2008

The animatronics technique could be very important fact of technique not only to achieve full completion of visible image but also to offer lots of chances to express images by merging CG, special effects and special devices. In this thesis, we design and implement the Zigbee-based wireless transceiver and communication program to control animal animatronics such as a dog and bear. The wireless control utilizing the Zigbee protocol is that electrically consumption is more small than the Bluetooth and reliability of data transmission is better. The implemented control systems and program have the normal and replay function for control of animal models. This functions and operability are tested by a designed animatronics prototype under the wireless environment.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.5
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• pp.9-17
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• 2010

In this paper we propose an improved hierarchical routing protocol for wireless hybrid mesh network. The proposed method efficiently manages network topology and reduces overhead traffic for setting routing path by considering link stability. The simulation results show that the proposed method outperforms the HOLSR (hierarchical optimized link state routing) method in aggregate goodput, packet delivery ratio, and end-to-end delay.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.6
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• pp.71-76
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• 2012

Recently, the huge growth of mobile data traffic has driven the earlier commercialization of LTE network and the evolution of LTE-Adv has been accelerated because of this trend of mobile traffic surges. Thus it has enabled the global connectivity and roaming capability due to continual standardization activities. The 3rd generation mobile communication system has been improved through incorporating technologies of HSDPA, MBMS and HSUPA etc continuously. Also, OFDMA/SC-FDMA-based LTE standardization has been under way. In this paper, the architectures of LTE network and protocol have been introduced and their inherent operation mechanisms have also been explored in order to give some insights about the LTE/LTE-Adv networks while their architectures are considered as most prominent candidate for worldwide standard by ITU-R and mobile operators for international communication networks.

• Journal of Advanced Navigation Technology
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• v.11 no.3
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• pp.296-305
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• 2007

The HiLow, a hierarchical routing protocol for 6LoWPAN, needs smaller memory allocation and energy than other routing protocols. However, the HiLow has a weak point that does not provide the optimized routing path. In this paper, we propose the algorithm that can find the optimum next hop using neighboring nodes around the source node as well as hierarchical routing path information. We evaluate the performance of proposed algorithm using the computer simulation, and we can acquire results that decreases a number of hop count and transmitted message.

• The KIPS Transactions:PartC
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• v.17C no.4
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• pp.371-378
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• 2010

In this paper, we propose a new energy-efficient routing algorithm for sensor networks that selects a least energy consuming path among the paths formed by node with highest remaining energy and provides long network lifetime and uniform energy consumption by nodes. The pair distribution of the energy consumption over all the possible routes to the base station is one of the design objectives. Also, an alternate route search mechanism is proposed to cope with the situation in which no routing information is available due to lack of remaining energy of the neighboring nodes. Simulation results show that our algorithm extends the network lifetime and enhances the network reliability by maintaining relatively uniform remaining energy distribution among sensor nodes.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10b
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• pp.1299-1302
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• 2001

인터넷의 폭발적인 증가와 다양한 무선 서비스에 대한 수요 증가에 따라 용량이 크고, 데이터 전송 속도가 빠르며, 멀티미디어를 지원 할 수 있는 무선 인터넷 서비스가 필요하게 되었다. 또한 증가하는 사용자수를 수용하기 위해서 마이크로/피코 셀(micro/pico cell)을 도입하게 되었고, 이로 인하여 빈번한 핸드오프가 발생하게 되었다[1,2]. 이를 해결하기 위해서 MRSVP(Mobile Resource reservation protocol)와 같은 무선 자원예약 프로토콜이 제안되어지고 있다(4). 제안된 MRSVP 에서는 자원예약 지역의 불명확성과 지나친 신호부하를 초래하게 되었고, 이를 해결하기 위해서 본 논문에서는 계층적 MRSVP(H-MRSVP)를 이용한 새로운 호 제어기법과 무선 자원 예약 기법에 대해 연구하였다.

• Journal of Internet Computing and Services
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• v.5 no.5
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• pp.39-48
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• 2004

For transporting real-time multimedia traffic, RTP is considered as one of the most promising protocols operating at application layer. In order to manage and control the real-time multimedia traffic within networks, network managers need to monitor and analyze the traffic delivering through their networks. However, conventional traffic analyzing tools can not exactly classify and analyze the real-time multimedia traffic using RTP on the basis of real-time as well as non-real-time operations. In this paper, we propose an efficient online classification method of RTP packets, which can be used on high-speed network links. The accuracy and efficiency of the proposed methodhave been tested using captured data from a KIX node with 100 Mbps links, which interconnects between domestic and overseas Internet networks and is operated by NCA.