• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.25-26
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• 2006

Azobenzene functionalized polymers have been extensively investigated due to the potential applications in the areas of optical switching, optical elements, optical information storage, and nonlinear optics. These applications are mainly achievable due to photoinduced properties of azobenzene groups with photoisomerization and photoinduced anisotropy. We report applications to the optoelectronic devices using inscribed one-(1D) and two-dimensional (2D) SRGs on azo polymer films. The inscribed holographic SRGs patterns were useful to control or enhance optoelectronic properties such as transparent electrode patterning, hybrid solar cell and ultraviolet GaN-based LED.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.1
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• pp.115-126
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• 1996

In the time optimal control problem, bang-bang control has been used becaese it is the theoretical time minimum solution. However, to improve tracking speed performance in the time optimal control, it is important to select a switching point accurately which makes the velocity zero near the target track. But it is not easy to select the swiching point accurately because of the damping coefficient variation and uncertainties of modeling an actual system. The Adaptive model following control(AMFC) is implemented to relieve the difficulty and inconvenience of this task. The AMFC and make the controlled plant follow as closely as possible to a desired reference model whose switching point can be calculated easily and accurately, assuring the error between the states of the reference model and those of the controlled plant appoaches zero. The hybrid control method composed of AMFC and PID is applied to a tracking actuator of the magneto optical disk drive(MODD) in random access devices to improve its slow tracking performance. According to the simulaion and experimental results, the average tracking time as small as 20ms is obtained for a 3.5 magneto-optical disk drive. The AMFC also can be applied for other random access devices to improve the average tracking performance.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.131-139
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• 2013

To overcome the limitations in performance and power consumption of traditional electrical interconnection based network-on-chips (NoCs), a hybrid optical network-on-chip (HONoC) architecture using optical interconnects is emerging. However, the HONoC architecture should use circuit-switching scheme owing to the overhead by optical devices, which worsens the latency unfairness problem caused by frequent path collisions. This resultingly exert a bad influence in overall performance of the system. In this paper, we propose a new task mapping algorithm for optimizing latency by reducing path collisions. The proposed algorithm allocates a task to a certain processing element (PE) for the purpose of minimizing path collisions and worst case latencies. Compared to the random mapping technique and the bandwidth-constrained mapping technique, simulation results show the reduction in latency by 43% and 61% in average for each $4{\times}4$ and $8{\times}8$ mesh topology, respectively.

• Journal of the Optical Society of Korea
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• v.11 no.2
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• pp.59-62
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• 2007

In this paper, we introduce a reliable, scalable, and cost-effective switchless wavelength division multiplexing (WDM) network based on a quality-of-service supporting reservation-based medium access control (MAC) protocol. The protocol not only provides both packet and circuit switching but also supports multicasting. The network efficiency is significantly increased by spatially reusing wavelengths and exploiting multiple free spectral ranges (FSRs) of arrayed waveguide grating (AWG) employed in the architecture. We have demonstrated the feasibility of this architecture by simulating in $Optsim^{TM}$.

• Korean Journal of Materials Research
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• v.19 no.10
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• pp.527-532
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• 2009

The electrochromic properties of Au nanoparticles (NPs) incorporating poly (3, 4-ethylenedioxythiphene) (PEDOT) film were investigated. Trisodium citrate was used for stabilizing Au NPs to control the size. The capping molecules of the Au nanoparticles were exchanged from citrate to 2-mercaptoethanol (2-ME). Water was removed by centrifuge and Au NPs were redispersed in methanol (MeOH). Finally, we obtained ca. 11.7 nm diameter of Au NPs. The effects of 0.15 at% of Au NPs incorporation on the optical, electrical, and eletrochromic properties of PEDOT films were investigated. The electrical property and switching speed of Au/PEDOT film was slightly improved over that of PEDOT film because Au NPs play a hopping site role and affect packing density of the PEDOT chain. Through the ultra violet-visible spectra of PEDOT and Au/PEDOT films at -0.7 V (vs Ag/AgCl), blue shift of maximum absorption peak was observed from PEDOT (585.4 nm) to Au/PEDOT (572.2 nm) due to a shortening of conjugated length of PEDOT. The Au NPs interfered with the degree of conjugation and the maximum absorption peak was shifted to shorter wavelength.

• Journal of Industrial Technology
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• v.15
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• pp.113-122
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• 1995

By integrating WDM to OPS unit which plays an important role for the reliability of CPN, we made it possible to provide CATV, VOD, and high-speed data services simultaneously and to meet the requirements for new services in the future. For the design of optimal system, the link analysis of power budget has been performed. Also, the prototyped system has been tested with STM-1 level signals to confirm functions such as transmission, distribution, and protection. The results proved that when occurred out-of-order or recovery of ONU, the system did the pertinent switching with minimum loss for high-speed data services. Also for video distribution services, the system has distributed STM-1 level signals successfully.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.11
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• pp.19-25
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• 2014

For effective updating a blind equalizer, we propose the adaptive algorithm having faster convergence speed required for initial equalization and satisfying low error level required in steady-state while having a gradual and reversible switching characteristics between initial stage and steady-state. The proposed method presents three criteria to distinguish the state of equalized signal, according to the criteria, differently updates the equalizer by using the hybrid error generation algorithm generating one of the three errors. Wherein as the criteria to determine the state of the equalized signal the confidence intervals on the signal constellation are used, an error is generated alternatively according to the confidence interval where equalizer output lies, and the equalizer is updated by, we got convergence quickly and to lower error level. In order to verify the usefulness of the proposed idea, simulation results were compared to the performance of conventional methods.