• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.4
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• pp.21-29
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• 1994

Three protocols based on the slotted Aloha technique are proposed for very high-speed optical fiber local area networks using wavelength division multiplexing (WDM) passive star topology and the throughputs and delays are derived. For getting a high probability in successful transmission of control packets determining the transmission of a data packet, we adopt control mini slot groups in these protocols. The retransmission probability is also considered in analysis. Both throughput and delay of three protocols are compared and analyzed by varying the number of control solt groups, the retransmission probability the length of a data packet and the number of channels. The numerical analysis shows that the proposed protocols adopted the control slot groups give the increase of throughput and the decrease of delay.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.7
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• pp.1026-1030
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• 2015

In this paper, we propose a signal processing board of an optical delay simulator for evaluating a long-range laser range finder and a laser target designator. We improved the accuracy by applying the clock multiplication and the correction of error gradient. To evaluate the performance of the proposed method, we implemented a prototype board and performed experiments. As a result, we implemented the optical delay simulator with resolution less than 0.7m in measuring distance 60km and a standard deviation of 0.041m. The PRF code detection logic and generation logic have a stability less than 0.03% and 0.08% compared to the NATO standard, respectively.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.3
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• pp.40-49
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• 2008

In this paper, we have described a Simulated Radar Target Generation Equipment(SRTGE) for evaluating the performance of a developed radar system. In order to change a simulated target range(or time delay), the variable optical delay line structure is used in SRTGE, In addition, SRTGE is required to generate a target return signal which is composed of variable amplitude and Doppler velocity. The interference such as noise jamming and clutter is also produced from SRTGE for evaluating ECCM(Electronic-Counter-Counter Measure) capability of radar.

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

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.78-79
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• 2001

노광 후 지연(Post Exposure Delay： PED) 효과는 그림 1과 같이 노광 후 지연 시간에 따른 감광제의 Profile에 thinning, T-top, foot, undercut 를 보여주는 현상으로 화학 증폭형 감광제(Chemically Amplified Resist, CAR) 개발에 있어 PED의 안정성은 중요한 요소이다(1). 따라서 노광후 지연 효과에 대한 모델링은 연구와 개발을 위한 시뮬레이션 tool에 있어 매우 의미 있는 일이다. T-top 이나 undercut 를 형성하는 Surface inhibition layer(SIL) 은 노광 후 지연시 발생되는 environmental base contamination, acid evaporation 이 주요 원인이며 다른 원인으로는 감광제 속에서 acid migration, spin coating 동안에 photoacid generator (PAG)의 고갈, internal basic impurities 이며 그 외에 nonbsic atmospheric contamination, high power laser source의 영향 등이 있다. (중략)

• ETRI Journal
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• v.29 no.1
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• pp.116-119
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• 2007

In this letter, we design a collision resolution protocol for optical burst switching ring networks to avoid burst collision. We define the offset time condition for no burst transmission collision and manage the free time list of nodes for no burst reception collision. In order to improve the throughput, we use a fiber delay line, void-filling, and void-compression. This protocol does not require any additional procedures for bandwidth reservation such as centralized assignment of bandwidth, lightpath setup of WDM ring networks, or token capturing for the burst transmission. The simulation results show that the proposed protocol can achieve high throughput while saving 70% of wavelengths when compared to round robin with random selection, round robin with persistent, and round robin with non-persistent with only destination delay.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.438-440
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• 2005

광위상변조기를 이용하여 OCT용 초고속 광지연단을 설계하고 수치해석을 수행하였다. 수치해석은 electro-optic 위상 변조기에 1310nm, 10ps의 펄스폭을 갖는 레이저 광원을 적용하여 수행하였다. 수치해석결과로 500MHz의 변조 주파수일때 19ps의 시간 지연을 얻었으며, 이는 기존의 기계적 검출방식(수십kHz)의 OCT장치에 비해 1000배이상 빠른 검출이 가능할 것으로 예상된다.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.86-88
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• 2004

As the rapid incensement of the number of internet users has occurred recently, many multimedia application services have been emerging. To improve quality of service, traffic can be suggested to be classified with priority in EPON(Ethernet Passive Optical Network), which is supporting the multimedia application services. In this paper, multimedia application services treat bandwidth classifying device in serving both delay sensitive traffic for real-time audio, video and voice data such as VoIP(Voice over Internet Protocol), and nonreal-time traffic such as BE(Best Effort). With looking through existing mechanisms, new mechanism to improve the quality will be suggested. The delay performances and packet losses of traffic achieved by supporting bandwidth allocation of upstream traffic in suggested mechanism will be analyzed with simulation.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.5
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• pp.80-87
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• 1999

We propose a new recirculating fiber delay-line filter structure. In proposed system, we insert a fiber Bragg grating(FBG) into a recirculating fiber delay line and it operates as a partially reflection mirror. Therefore, the transfer function of the system is given by the recirculating delay output part and the multiple-reflected output part due to a FBG. By adjusting the parameters such as coupling coefficient, reflectivity of FBG, and gain, we can make the system operate in various filter.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.330-333
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• 2000

With the recent development of the ultrahigh-speed optical time division multiplexed system, high-repetition rate optical-pulse stream generation is necessary. This is different from conventional approaches, which use fiber or integrated waveguide delay line circuits. The high-repetition-rate optical-pulse multiplication phenomenon occurs when the optical pulse's spectral width is greater than the transfer bandwidth of the coupler used. From the analysis, the output repetition rate can be controlled by using fiber couplers with different equivalent transfer bandwidths. The pulse seperation spacing is controlled by number of cascaded coupler in optical loop mirror coupler scheme.