• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.1
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• pp.159-169
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• 1994

A multichannel optical slotted ring network is designed using a wavelength division multiplexing(WDM) technique and photonic packet switching devices. The electronics speed bottleneck is removed out of the ring, which allows utilization of the full bandwidth for the optical fiber transmission medium. The ring channel adopts a slotted ring concept with a destination cell remove strategy for the eing access mechanism. The slot size in the ring is selected as the same as that of ATM based cell in order to be used as B-ISDN Access Networks. In this paper, we devised a mathematical method to measure the average transfer delay characteristics of the network. The analytical method turned out to yield accurate results over a broad range of parameters in comparison to simulation results. From the study, we observed the average transfer delay of the network as the network parameters vary.

• Korean Journal of Optics and Photonics
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• v.12 no.2
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• pp.129-134
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• 2001

Novel supervisory system for WDM transmission link using conventional optical time domain reflectometry was presented. By modifying the structure of erbuim doped fiber amplifier to support bi-directional transmission at arDR pulse wavelength and launching the optical pulse into transmission link in the opposite direction of data signal propagation to avoid the distortion by cross-gain modulation, it is possible to monitor the WDM link in service. To prove the validity of proposed scheme, the supervision result of 2.5 Gbps $\times$ 8 channel WDM 320 km transmission system in service by arDR was presented. And power penalty due to monitoring was measured as smaller than 0.3 dB. .3 dB.

• Korean Journal of Optics and Photonics
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• v.8 no.6
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• pp.486-491
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• 1997

A division-of-amplitude type photopolarimeter has been constructed for the analysis of the dynamic optical characteristics of liquid crystal panels, one of the essential components of liquid crystal displays. In this instrument an incoming light ray, whose state of polarization is to be determined, is divided into three rays of nearly same intensities and of identical polarization state by using NPBS'(non-polarizing beam splitters). Each of the three rays is further divided into two components of orthogonal polarization states by using a PBS(polarizing cube beamsplitter) or by using a combination of a quater wave plate followed by a PBS. The intensity of each ray is measured by using a photodiode to produce a set of six photo-signals, which in turn are converted into four Stokes parameters describing the state of polarization of the incoming ray. Performance test of the insrument shows that its time resolution is 80 $mutextrm{s}$, accuracy $\pm$0.3 degrees when the state of polarization of the incoming ray is representated on the Poincare sphere.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.6
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• pp.1-11
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• 2000

In this paper, we propose a novel control signaling protocol that efficiently controls connection setup and increases the utilization of network resources. The proposed protocol, Separated Control Signaling Protocol(SCSP), separates bearer control from call control lot WDM optical networks. The main function of call control is to check the availability of network resources such as wavelengths and receivers at destination node. Bearer control is to reserve and assign wavelengths. The signaling architecture of this protocol consists of call controller and hearer controller The call controller handles call setup and release, activates the beater controller, and manages the status of call and bearer. The bearer controller reserves wavelengths, sets up bearer, tears down bearer. and notifies the status of beater to call controller. The state transition diagrams of each controller are designed. Using control messages and related primitives, the information flows for call setup and bearer setup, hearer teardown and call release, and reaction for setup failures are described to evaluate the performance. The simulation results show that the separated control signaling protocol is superior to conventional one in terms of call blocking probability and resource utilization.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3A
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• pp.443-450
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• 2000

Although designing a virtual topology for all-optical WDM wide-area networks has been extensively studied and several algorithms have been proposed, these algorithms assumed error-free communication between two nodes. However, noises from optical amplifiers and optical cross-connects can degraded the signal, resulting in a nonzero bit-error rate. In this paper, we investigate the effect of physical limitations on the virtual topology design. We show that for side-area all-optical networks where transmission distance is fairly long, virtual topology design algorithm that can determine the locations of opto-electronic(OE) and electro-optic(EO) conversions to set up a connection request with a high BER in a multihop manner.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.150-151
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• 2002

파장 분할 다중화(Wavelength division multiplexing ： WDM) 광전송 장치의 용량확대를 위한 방안으로 여러 가지 방법들이 연구 개발되고 있으며, 최근 들어 테라 급(Tb/s) 광전송 연구 결과들이 발표되고 있다. 이러한 장거리 광전송 장치의 광송신기는 LiNbO$_3$ 마하-젠더(Mach-Zehnder) 간섭계형 외부 변조기를 주로 사용하고 있다. 한편 반도체 레이저 집적된 전계 흡수형 변조기(Electro-absorption modulator integrated laser ： EML)를 이용한 외부 변조 방식 적용을 위해서 여러 연구소 및 기업체에서는 40Gb/s의 성능을 지닌 EML의 개발 결과들을 발표하고 있다. (중략)

• Electronics and Telecommunications Trends
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• v.19 no.6 s.90
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• pp.1-12
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• 2004

1960년대에 발명된 광섬유를 이용한 광통신기술은 1980년대 이래 빠르게 보급되었다. 특히 인터넷 트래픽이 폭발적으로 증가하기 시작한 1990년대 후반에 파장 분할 다중화(WDM) 기술이 상용화 되었으며 이 기술은 불과 수년 사이에 하나의 물리적인 광섬유 한 가닥을 통해 독립적인 수백 채널의 신호를 전송할 수 있는 수준에 이르렀다. 이에 더하여 ETDM 기술의 발전으로 채널 당 10Gbps 내지 40Gbps에 이르는 신호를 전송할 수 있게 되어 광섬유 선로 당 전송 용량은 테라급이 가능해졌다. 전송 용량의 빠른 확장과 과장된 수요 예측은 결국 공급 과잉을 초래하여 최근 수 년간 광전송 분야 시장이 침체된바 있다. 그러나 매년 약 두 배씩 꾸준히 증가하는 트래픽 덕에 최근에는 과잉 공급 분이 소진되어 가고 있으며 새로 시장이 활성화되고 있다. 새 시장에서는 종래의 점대점 방식을 넘어 메시형의 WDM 광 네트워크가 등장할 것이며 이에 따른 다양한 요소 기술을 요구하게 될 것이다. 본 고에서는 광전송 기술의 핵심 분야인 광 트랜스폰더 기술, 광 증폭기 기술, 그리고 광 네트워크 기술을 중심으로 현황과 발전전망을 알아본다.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.3
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• pp.553-558
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• 2012

An effort for motion control of multi-axis in robot have been continued recently. In this paper, we propose implementation method for AC servo driver that can be easily motion control of multi-axis in robot. This proposed method implement EtherCAT communication technologies of bi-directional optical communication based on single optical core method that applied WDM for communication between control stage which is upper and AC servo drive stage.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.397-399
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• 2003

파장분할다중화방식(WDM-Wavelength Division Multiplexing) 네트워크는 차세대 전송망으로서 주목받고 있다. 광경로들의 집합으로서 WDM 네트워크의 가상 토폴로지가 정의되는데, 각각의 광경로를 정의하는 광학 스위치들이 재구성 가능하기 때문에, 가상 토폴로지 또한 재구성 가능하게 된다. 이러한 WDM 네트워크의 특징은 IP, SONET, ATM과 같은 클라이언트 층이 요구하는 트래픽 패턴에 따라 가상 토폴로지를 재구성함으로서 네트워크 성능을 최적화시킬 수 있게 된다. 본 논문에서는 시간에 따라 변화하는 트래픽 패턴 하에서 가상 토폴로지를 재구성하면서, 각 광경로의 트래픽에 대한 로드벨런싱을 수행하는 기법을 제시한다. 이 기법은 기존의 기법들과 달리 미래의 트래픽 패턴을 알고 있다는 가정을 필요로 하지 않으며, 동적인 워터마즈 결정을 통해 전범위에서의 로드벨런싱을 수행하게 된다.

• 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.