• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9B
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• pp.1551-1562
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• 2000

In the using of FBG developed in home land, we designed and manufactured three types of FBG sound transducers the first in Korea. On FBG transducers manufactured we made an demonstrated on respective frequency response peculiarties in the water and analyzed the special characters. As the experimental result on frequency response peculiarities, we made t possible underwater acoustic detection on C type to maximum 18kHz, And for the purpose of realization on multi-point signal detection on wide scope in the water, in the using of WDM(Wavelength Division Multiplexing) method and passive band-pass filter system, established arrays system and succeeded in multi-point underwater acoustic signal detection to the frequency 1.3KHz out of the two B type FBG transducers. Additionally, it would be possible directivity detection for the objects of its source as the intensity of detection signal varies with the sound source's direction and angle. From now on we prepared a new moment on the practical used study on FBG hydrophone.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9B
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• pp.793-805
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• 2003

In OBS (Optical Burst Switching) networks which decouple the burst from its header, the fault of a fiber link can lead to the failure of all the light-path that traverses the fiber. Because each light-path is expected to operate at a rate of a few Gbps by using WDM (Wavelength Division Multiplexing) technology, any failure may lead to large data loss. Therefore, an efficient recovery scheme must be provided. In this paper, we analyze network utilization and BCP (Burst Control Packet) loss rate according to each link failure by applying the conventional restoration schemes in OBS networks. And through these simulation results, an ASPR scheme is proposed improve the fault management scheme in terms of recovery time and throughput. Finally, We compare the performance of our proposed scheme with that of the conventional one with respect to burst loss rate, resource utilization and throughput by OPNET simulations.

• The Transactions of the Korea Information Processing Society
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• v.5 no.8
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• pp.2013-2026
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• 1998

In optical passive star interconnections, all packets are transmitted between nodes ina broadcast and-select manner. It is assumed that each node has a innable transmitter and a fixed-savelength receiver, ad that all packet lengths are equal so that each transmission can be done in a unit time. The tuning delay, denoted by $\delta$, means the amount of time for transmitter to change its wavelength to another one. The problec is , given ay value of the mumber of nodes N and the number of wavelengths $\kappa$ according to WDM implementations, to find transmission schedules with minimum cycle length for all-to all brondcaxt where no one sends any packet to itself. In this paper, we prove that the cycle length of optimal transcission schedules should be at least $max[[{\frac{N}{k}](N-1)}]$,$k\delta$$+N-1$. A novel algorithm for optimal transmission schedules is then presented when N-1 is divisible by $\kappa$. This algorithm also can be used for any values of N and $\kappa$ if the tuning delay $\delta$ does not affect strictly the cycle length of transmission schedules, i,e, $[\frac{N}{k}](N-1)$ > $\kappa\delta$+N-1.