• Proceedings of the KSRS Conference
• /
• 2008.10a
• /
• pp.232-235
• /
• 2008

The mission of the EO(electro-optical) based low earth orbit satellite is provision of the high-resolution images required for GIS(Geographical Information Systems) establishment and the applications for environmental, agriculture and ocean monitoring. AEISS(Advanced Earth Imaging Sensor System) which is the main payload on the satellite consists of EOS(electro-optical subsystem) and PDTS(Payload Data Transmission Sub-system). IDHU(Image Data Handling Unit) which is one of the major unit in PDTS is capable of compression, storage, encryption and encoding. In this paper, the payload system of the EO based satellite is briefly introduced and the influence of the compression on AEISS is analyzed.

• Journal of applied mathematics & informatics
• /
• v.16 no.1_2
• /
• pp.469-481
• /
• 2004

In this paper, we investigate the mean queue length and the mean packet delay of a dynamic bandwidth allocation(DBA) scheme in an Ethernet passive optical network(EPON). We focus on the interleaved polling system with a gated service discipline. We assume that input packets arrive at an optical network unit(ONU) according to Poisson process. We use a continuous time queueing model in order to find the queue length distribution of the gated interleaved polling system with the first stage input queue and the second stage transmission queue. We give some numerical results to investigate the mean queue lengths and mean packet delays for the symmetric polling system with statistically identical stations.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2005.07a
• /
• pp.439-442
• /
• 2005

In this paper, we propose a cell structure to improve transmittance and aperture ratio with FFS(Fringe Field Switching) mode. As an exemplary cell, we selected conventional FFS cell with dual domain. Optical transmittance and aperture ratio were calculated with 3DFEM numerical solver, TechWiz LCD. The simulation results revealed that transmission increases by more than 10% while aperture ratio increases by more than 4% when compared to conventional FFS mode.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.6
• /
• pp.58-64
• /
• 1997

The wavelengt lockin gsystem of the optical fabry-perot filter theoretially derived and experimentally realized by using the ithering method in order to compensate the laser wavelength drift increasing the BER of the WDM system. The deviation between the laser wavelength and the optical filter center wavelength is compensated by applying a suitable voltage to the PZT. Accordingly, the laser wavelength selected by the fabry-perot filter always maintains the condition of maximum transmission powr. A wavelength locking system has been demonstrated using a fiber fabry-perot filter with a free spectral range of 80nm and an FWH of 1nm. The voltages of the sine wave generated for dithering was 20mV and 10mV, the frequency was 2kHz and center wavelength of the tunable laser was 1550nm. In this paper, the locking system have 20ms of locking time and 2nm of locking range.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.4
• /
• pp.793-796
• /
• 2010

The equalizer compensates a signal distorted by transmission lines and amplifying stages, so the signal can have uniform characteristics over all frequency range. The equalizer in ODD(Optical Disc Drive) improves the stability of the extracted clock from a received signal and the readability of an inserted disc by suppressing noise and ISI(Inter-Symbol Inference). The length of marks-spaces and track pitch on discs becomes shorter as the recording density of an optical media is higher, which causes noise and ISI. And, the sensitivity about the fluctuation of physical systems is higher as the optical devices become more complicate. This paper proposes a method to select the coefficient of built-in equalizer of ODD in order to maintain the quality of signals against noise and ISI caused by system fluctuation.

• Proceedings of the KIEE Conference
• /
• 2004.11c
• /
• pp.663-665
• /
• 2004

Ethernet-based passive optical network(EPON) technology is being considered as a promising solution for next-generation broadband access network. It must have the property of high efficiency, low cost, and support quality of service(QoS). A major feature for this new architecture is the use of a shared transmission media between all connected optical network unit(ONU). Hence, medium access control(MAC) arbitration mechanisms are essential for the successful implementation of EPON. In this paper we propose a simple dynamic bandwidth allocation(DBA) algorithm that improves the performance of network and supports IP-based multimedia applications with the bursty data traffic. In addition, we introduce analytic models of proposed algorithms and prove the system based on our algorithm to be asymptotically stable. Simulation results show the new DBA algorithm provides high bandwidth efficiency and low queueing delay of ONU in EPON.

• IEIE Transactions on Smart Processing and Computing
• /
• v.1 no.1
• /
• pp.27-33
• /
• 2012

The Ethernet Passive Optical Network (EPON) has been considered to be one of the most promising solutions for the implementation of the Fiber To The Home (FTTH) technology designed to ameliorate the "last mile" bandwidth bottleneck. In the EPON network, an efficient and fair bandwidth allocation is a very important issue, since multiple optical network units (ONUs) share a common upstream channel for packet transmission. To increase bandwidth utilization, an EPON system must provide a way to adaptively allocate the upstream bandwidth among multiple ONUs in accordance to their bandwidth demands and requirements. We present a new hybrid method that satisfies these requirements. The advantage of our method comes from the consideration of application-specific bandwidth allocation and the minimization of the idle bandwidth. Our simulation results show that our proposed method outperforms existing dynamic bandwidth allocation methods in terms of bandwidth utilization.

• 한국정보통신설비학회:학술대회논문집
• /
• 2002.08a
• /
• pp.130-132
• /
• 2002

기존의 광선로 특성 데이터에 대한 관리는 대부분 지역별 국소별로 수작업에 의존하였기 때문에 처리 절차의 일원화 및 체계화가 제대로 정립되어 있지 않았다. 이로 인해 선로 자원의 사용이 원활하지 못하였고 최적의 망을 구축하는데 많은 시간 인력 및 비용이 소요되는 등 비효율적인 문제점들이 도출 되었다. 이러한 문제점을 해결하기 위해 본 논문에서는 수작업에 의존했던 광 전송로의 특성 정보를 데이터베이스화하여 데이터에 대한 다양한 가공 능력 및 투자에 대한 일관성 있는 의사 결정 능력을 제시하였으며, 구축된 데이터베이스를 통해 최적의 광통신망 설계를 지원할 수 있도록 광전송로 관리 및 설계 처리에 대한 의사 결정 시스템을 제안했다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.05a
• /
• pp.625-626
• /
• 2015

The optimal distribution pattern for the compensation for the distorted WDM signals due to the group velocity dispersion (GVD) and the nonlinear Kerr effects is induced in $80km{\times}50spans$ optical link with an artificial distributions of single mode fiber (SMF) lengths and residual dispersion per span (RDPS).

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.11
• /
• pp.3955-3966
• /
• 2014

With the exponentially increasing Internet traffic and emergence of more versatile and heterogeneous applications, the design of datacenter networks (DCNs) is subject to unprecedented requirements for larger capacity and more flexible switching granularities. Envisioning Optical-Orthogonal Frequency Division Multiplexing (O-OFDM) as a promising candidate for such a scenario, we motivate the use of O-OFDM as the underlying switching technology in order to provide sufficient switching capacity and elastic bandwidth allocation. For this purpose, this article reviews the recent progresses of DCN deployment and assesses the scenario where the O-OFDM transmission and switching technology is employed in the underlying transport plane. We discuss the key issues of the datacenter-oriented O-OFDM optical networks, and in particular, elaborate on a number of open issues and solutions including system interconnection architecture, routing and resource assignment, survivability, and energy-efficiency.