• Proceedings of the Optical Society of Korea Conference
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• 2001.08a
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• pp.154-155
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• 2001

A laser system for therapy of cancer is proposed in this paper. In order to accuracy and statistical output control we used the constant current control method and designed the power source to protect the resonator from the over -current, rush-current and electrical fault. The most important things are the radiation type for cancer therapy in laser system, we developed the radiation type of cw, pulse, and burst pulse. The experimental result show that laser beam power increase linearly from 100mW to 300mW for input current increasing and the exposure time.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.2
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• pp.409-415
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• 2012

Recently in industry communication, the efforts that use robot and automation system increased by cooperation with optical communication and industrial Ethernet. In this paper, in order to solve the problem that total network blocking when network fault happens and wiring problem of optical cable, which were big serious disadvantage in industrial optical network systems, we propose bi-directional optical EtherCAT communication technique based on single optical core, which applying WDM method. We describe the content for implementation of WDM bi-directional optical EtherCAT communication module and performance evaluation to verify the performance of related technology as a whole.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.120-120
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• 2004

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.94-105
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• 2003

OBS(Optical Burst Switching) networks which decouple the burst from its header has characteristic one-way reservation. Therefore, the fault of a fiber link may lead to the magnitude of burst loss. Since sending a header packet and using an offset time before the transmission of the corresponding burst. In this paper, we analysis a offset time based on the burst loss rate resulting from only link failure and by applying the restoration schemes in an optical burst switching networks. The simulation results in terms of the effect of a offset time is evaluated in our network model to verify that comparing the numerical analysis with simulation result. Finally, and through these results, We propose the new restoration scheme based on offset time considered Quality of Service.

• Current Optics and Photonics
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• v.7 no.1
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• pp.47-53
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• 2023

We propose a centralized passive-optical-network monitoring scheme using the resonance-spectrum properties of a Fabry-Perot cavity based on fiber Bragg gratings. Each cavity consists of two identical uniform fiber Bragg gratings and a varying cavity length or grating length, which can produce a unique single-mode resonance spectrum for the drop-fiber link. The output spectral properties of each cavity can be easily adjusted by the cavity length or the grating length. The resonance spectrum for each cavity is calculated by the transfer-matrix method. To obtain the peak wavelength of the resonance spectrum more accurately, the effective cavity length is introduced. Each drop fiber with a specific resonance spectrum distinguishes between the peak wavelength or linewidth. We also investigate parameters such as reflectivity and bandwidth, which determine the basic performance of the fiber Bragg grating used, and thus the output-spectrum properties of the Fabry-Perot cavity. The feasibility of the proposed scheme is verified using the Optisystem software for a simplified 1 × 8 passive optical network. The proposed scheme provides a simple, effective solution for passive-optical-network monitoring, especially for a high-density network with small end-user distance difference.

• Journal of the Korean Society for Railway
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• v.15 no.2
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• pp.122-128
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• 2012

Considering structure of depot, it is impossible to install the track circuit systems due to iron-beam. Because rails and earth are connected by the iron-beam, there is much leakage current. So, it is hard to apply the track circuit systems. Thus, when trains go to the depot, sign which indicates existence of trains is used manually. In case of wrong sign, accidents occur such as train crash, derailment etc. Currently, location of trains has been found by using optical sensor in the depot to prevent the accidents. However, it costs a great deal to install and maintain the optical sensor. Therefore, this method is hardly used in train operation institutes. In this paper, virtual track circuit systems are introduced by using software program in the depot. Also, algorithm of the virtual track circuit systems is proposed. In case that signal is handled to the depot which is occupied by the train, safety is ensured by indicating sign which means existence of trains and stop signal. Also, proper fault tolerance techniques are proposed to the software by analyzing reliability and availability.

• Industrial Engineering and Management Systems
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• v.14 no.4
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• pp.392-400
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• 2015

Monitoring of plasma etch processes for fault detection is one of the hallmark procedures in semiconductor manufacturing. Optical emission spectroscopy (OES) has been considered as a gold standard for modeling plasma etching processes for on-line diagnosis and monitoring. However, statistical quantitative methods for processing the OES data are still lacking. There is an urgent need for a statistical quantitative method to deal with high-dimensional OES data for improving the quality of etched wafers. Therefore, we propose a robust relevance vector machine (RRVM) for regression with statistical quantitative features for modeling etch rate and uniformity in plasma etch processes by using OES data. For effectively dealing with the OES data complexity, we identify seven statistical features for extraction from raw OES data by reducing the data dimensionality. The experimental results demonstrate that the proposed approach is more suitable for high-accuracy monitoring of plasma etch responses obtained from OES.

• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.131-135
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• 2023

Neural network-based time series models called time series neural networks (TSNNs) are trained by the error backpropagation algorithm and used to predict process shifts of parameters such as gas flow, RF power, and chamber pressure in reactive ion etching (RIE). The training data consists of process conditions, as well as principal components (PCs) of optical emission spectroscopy (OES) data collected in-situ. Data are generated during the etching of benzocyclobutene (BCB) in a SF₆/O₂ plasma. Combinations of baseline and faulty responses for each process parameter are simulated, and a moving average of TSNN predictions successfully identifies process shifts in the recipe parameters for various degrees of faults.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3B
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• pp.504-509
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• 2000

This paper presents a noble operation and maintenance system for the optical subscriber loops and its feasibility through several experiments. In this system, a broadband CW (Continuous Wave) light source I used as monitoring of testing signals. and a FGF(Fiber Grating Filter) of which reflective wavelength is independent, is inserted somewhere in each subscriber loop for the reflection of monitoring of testing signals. The propose of the system is quick decision. whether the loop is just fault or not. rather than detailed information of loop state. At present, most of operation and maintenance system for the optical subscriber loops adopts OTDR(optical time domain reflectometer) for testing function. the OTDR is useful for detailed test, but not adequate for simple test because of long testing time . And it is difficult to test PON network by using general OTDR that has a single-wavelength light source. Compared to using OTDR, the proposed system can afford to shorten testing time and to test PON network. Moreover, we can cut down the system cost by simplifying circuits of the optical light sources. Our results show that the proposed system operates well according to the purpose mentioned above.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.7
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• pp.592-602
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• 2013

The purpose of this study is to optical cable closure and fiber line monitoring system. The current optical cable closure cases have not had any systems that help the central control station recognize opening as well as closing the cases in real-time when opening B2B and B2C lines. to solve this problem, it is considered to create systems that go off alarms, real-time fault location immediately, set alarms for open and close monitoring optical cable closure, and inspect regularly whether optical cables are deficient when monitoring the optical line in real-time and cutting them, in this paper, the monitoring system whose the central control station finds an optical signal block immediately and goes off the alarms when line workers separate components like a connector or a tray from the optical cable closure through OTDR. this study can contribute to stabilize the network quality through the quick and effective operation of the cables.