• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.42 no.12
• /
• pp.135-140
• /
• 2005

This paper proposes the technique of load balancing with traffic which is concentrated to MAP on the hierarchical mobile IPv6. This technique sends the secondary MAP address using the extension option of IPv6, so the upper level MAP will manage it. Therefore, when the overload occurs, it distributes the overload to the secondary MAP address by using redirect tunneling technique, so the efficient communication becomes possible. We validate the feasibility and result of the proposed technique by using ns-2 simulator.

• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.583-584
• /
• 2015

In this paper, the numerical results concerning different orbits of a 3D axisymmetric non-rotating galactic potential are presented. We use $Paczy{\acute{n}}ski^{\prime}s$ gravitational potential with different birth velocity distributions for the isolated old Neutron Star (NS) population. We note some smooth non-constant segments corresponding to regular orbits as well as the characterization of their chaoticity. This is strongly related to the effect of different kick velocities due to supernovae mass-loss and natal kicks to the newly-formed NS. We further confirm that the dynamical motion of the isolated old NSs in the gravitational field becomes obvious, with some significant diffraction in the symmetry of their orbital characteristics.

• Journal of the Korea Society of Computer and Information
• /
• v.10 no.3 s.35
• /
• pp.219-227
• /
• 2005

Since multicast in the mobile environments is based on packet transmission and independent addressing, this paper propose an improved scheme about how to manage the multicasting group and to set the communication path in the mobile environment by applying two-level addressing mode, which is similar to mobile IP, for location-independent address setting. And we propose the smooth handoff scheme that minimizes the handoff delay for mobile multimedia services. Performance analysis by the modified NS-2 network simulator has showed that the proposed scheme is better than other techniques in terms of handoff delay and transmitted packets' throughput.

• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 2004.11a
• /
• pp.170-170
• /
• 2004

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.11C
• /
• pp.877-884
• /
• 2010

This paper presents a fast IP mobility management scheme in vehicular networks where multiple wireless network interfaces are used to perform the fast handover without packet loss and handover latency. In order to do that, the IETF standard HMIPv6 has been extended, where multiple simultaneous tunnels between the HMIPv6 MAP and the mobile gateway are dynamically constructed. The architecture for supporting multiple tunnels has been designed and both mathematical analysis and simulation using NS-2 have been done for performance evaluation.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.1A
• /
• pp.75-82
• /
• 2007

This paper proposes the way that reduces power consumption of the IEEE 802.15.4-based sensor network. To reduce power consumption, we consider following two schemes; first scheme is the Adaptive Beacon Interval Control. The next is the Adaptive Superframe Duration Control. Our results show that these guarantee reducing power consumption in ns-2 simulator.

• Proceedings of the KIEE Conference
• /
• 2003.07c
• /
• pp.1662-1664
• /
• 2003

An electron gun system for a nanosecond pulse linac has been built and tested. The gun grid is driven with a grid pulser, which consists of an avalanche transistor pulser and parallel triode amplifier. The amplifier is installed in an end hole of the electron gun and provided for power amplification and polarity change of the output pulses of the avalanche transistor pulser. An output pulse of 200 V and 2 ns FWHM was obtained by using the grid pulser of can type transistors. Measurements with a test bench show that the electron gun can deliver 2ns pulse with with currents larger than 3A.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.6 no.1
• /
• pp.379-394
• /
• 2012

The ever-increasing demand for H.264 scalable video coding (H.264/SVC) distribution motivates researchers to devise ways to enhance the quality of video delivered on the Internet. Furthermore, researchers and practitioners in general depend on computer simulators to analyze or evaluate their designed network architecture or proposed protocols. Therefore, a complete toolset, which is called myEvalSVC, for evaluating the delivered quality of H.264/SVC transmissions in a simulated environment is proposed to help the network and video coding research communities. The toolset is based on the H.264 Scalable Video coding streaming Evaluation Framework (SVEF) and extended to connect to the NS2 simulator. With this combination, people who work on video coding can simulate the effects of a more realistic network on video sequences resulting from their coding schemes, while people who work on network technology can evaluate the impact of real video streams on the proposed network architecture or protocols. To demonstrate the usefulness of the proposed new toolset, examples of H.264/SVC transmissions over 802.11 and 802.11e are provided.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.12B
• /
• pp.1498-1505
• /
• 2009

In centralized control sensor network, tree-based multi-channel communication overcomes the recurrent channel switching and makes possible to transfer data simultaneously from different sources. In our paper, we propose a greedy algorithm named as NIT (Non-Intersecting Tree) that the trees can avoid inter-tree interference. We also propose channel switching technique by which trees can avoid link failure or area blocking due to external interference locally without rerunningthe algorithm and without interrupting the whole network. At first we applied our algorithm for a random topology and then we evaluate the performance of the network using NS-2 simulator. The results show that with the increasing of channel the throughputand delivery ratio are increased significantly. We got better performance than a using a recent proposed Tree-based Multi-Channel Protocol (TMCP).

• Current Optics and Photonics
• /
• v.5 no.2
• /
• pp.180-185
• /
• 2021

A femtosecond-laser inscribed Yb:YAG surface channel waveguide (WG) laser with single-walled carbon nanotubes deposited on the top surface of the WG was passively Q-switched by evanescent field interaction. Q-switched operation of the 14-mm-long compact Yb:YAG WG laser was achieved near 1031 nm with two different pumping schemes (single- and double-pass pumping) with an output coupling transmission of 91%. The Q-switched pulse characteristics depending on the absorbed pump power were investigated for both pumping geometries and analyzed in detail based on theoretical modeling. The best performances (energy/pulse duration) for each configuration were 204.4 nJ/75 ns at a repetition rate of 1.87 MHz, and 201.1 nJ/81 ns at 1.75 MHz for single- and double-pass pumping, respectively.