• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.5
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• pp.27-35
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• 2008

In order to determine the most appropriate recycling line to treat old corrugated container (OCC) to substitute unbleached kraft pulp (UKP) for the manufacture of kraft paper, three recycling lines were evaluated in pilot scale tests. The recycling line consisting of kneading, flotation, washing, dispersion and screening steps was able to produce pulp with acceptable appearance. Kneading was shown to be more efficient treatment to reduce specks than dispersion. In addition, 0.2 mm slot screen was very effective to remove specks. Severe damages on fiber morphology such as shortening of fiber and formation of fines were not observed during mechanical treatments such as kneading and dispersion. Most of strength properties of the kraft paper produced with the recycled pulp were found to be slightly increased after treated in the recycling lines.

• Journal of the Optical Society of Korea
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• v.13 no.1
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• pp.107-111
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• 2009

The properties of the chirped fiber Bragg grating (CFBG) as a chromatic dispersion compensator in differential phase-shift-keyed (DPSK) transmission are analyzed. Comparisons of a performance of a CFBG in between DPSK and On-Off Key (OOK) are shown by simulations using the commercial numerical modeling software, $OptSim^{TM}$. In the simulation, we compared the performance of the CFBG when they were used in the RZ-OOK 40 Gbps and the RZ-DPSK 40 Gbps transmission. The simulation results show the performance of an overall transmission with a CFBG in DPSK is inferior to the case of OOK, although DPSK generally has a 3 dB higher SNR (signal-to-noise ratio) than OOK.

• Journal of the Optical Society of Korea
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• v.17 no.1
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• pp.57-62
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• 2013

We have numerically implemented a receiver side all-optical signal processing method, i.e. optical backward propagation (OBP), by dispersion compensating fiber (DCF) and non-linear compensator (NLC) devised by effective negative Kerr non-linear coefficient using two highly non-linear fibers (HNLFs). The method is implemented for the post-processing of fiber transmission impairments, i.e. chromatic dispersion (CD) and non-linearities (NL). The OBP module is evaluated for dual-polarization (DP) m-ary (m=4,16,32,64,256) quadrature amplitude modulation (QAM) in 112 Gbit/s coherent transmission over 1200 km standard single mode fiber (SMF). We have also investigated an intensity limited optical backward propagation module (IL-OBP) by using a self-phase modulation-based optical limiter with an appropriate pre-chirping to compensate for the intensity fluctuations in the transmission link. Our results show that in highly non-linear sensitive 256QAM transmission, we have observed a 66% increase in the transmission distance by implementing IL-OBP as compared to conventional OBP.

• Advances in concrete construction
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• v.15 no.6
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• pp.405-417
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• 2023

While ultra-high performance concrete (UHPC) is commonly reinforced with micro straight steel fibers in existing applications, studies have indicated that the use of deformed steel macro-fibers leads to enhanced ductility and post-peak responses for UHPC structural elements, which is of particular importance for earthquake-resistant structures. However, there are potential concerns regarding the use of UHPC reinforced with macro-fibers due to the issues of workability and fiber distribution. The objective of this study was to address these issues by extensively investigating the restricted and non-restricted deformability, filling ability, horizontal and vertical velocities, and passing ability of UHPC containing macro hooked-end steel fibers. A new approach is suggested to examine the homogeneity of fiber distribution in UHPC. The influences of ultra-fine fillers and steel macro-fibers on the workability of fresh UHPC and the mechanics of hardened UHPC were examined. It was found that although increasing the ratio of quartz powder to cement led to an improvement in the workability and tensile strain hardening behavior of UHPC, it reduced the fiber distribution homogeneity. The addition of 1% volume fraction of macro-fibers in UHPC improved workability, but reduced its compressive strength, which is contrary to the effect of micro-fiber inclusion in UHPC.

• Journal of Advanced Navigation Technology
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• v.25 no.4
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• pp.286-292
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• 2021

Dispersion maps of antipodal symmetric type for improvement of compensation effect in dispersion managed link combined with optical phase conjugation, which can compensate for the distorted wavelength division multiplexed (WDM) signals due to chromatic dispersion and nonlinear Kerr effects of single-mode fiber, were proposed. It was confirmed that the proposed all of antipodal symmetric dispersion maps was more effective to compensate for the distorted WDM channels than the conventional link of uniform type dispersion map. Especially, dispersion maps formed like the inversion of alphabet S were more advantageous as the distorted WDM channels were compensated than dispersion maps formed like alphabet S. It was expected that the variety of optical network topology was more expanded by applying the proposed antipodal symmetric dispersion maps into transmission link.

• Journal of the Korea Institute of Building Construction
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• v.24 no.2
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• pp.203-213
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• 2024

This study delves into the mechanical properties of fiber-reinforced cement composites(FRCC) concerning the dispersion method of multi-walled carbon nanotubes(MWCNTs). MWCNTs find utility in industrial applications, particularly in magnetic sensing and crack detection, owing to their diverse properties including heat resistance and chemical stability. However, current research endeavors are increasingly directed towards leveraging the electrical properties of MWCNTs for self-sensing and smart sensor development. Notably, achieving uniform dispersion of MWCNTs poses a challenge due to variations in researchers' skills and equipment, with excessive dispersion potentially leading to deterioration in mechanical performance. To address these challenges, this study employs ultrasonic dispersion for a defined duration along with PCE surfactant, known for its efficacy in dispersion. Test specimens of FRCC are prepared and subjected to strength, drawing, and direct tensile tests to evaluate their mechanical properties. Additionally, the influence of MWCNT dispersion efficiency on the enhancement of FRCC mechanical performance is scrutinized across different dispersion methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.6
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• pp.462-469
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• 1988

Choromatic dispersion of single mode optical fibers limits the maximum bit rate in the single mode optical transmission systems. In this paper we calculate chromatic dispersion and dispersion parametes(zero dispersion wavelength, dispersion slope) for concatenated single mode optical fibers form the chromatic dispersion and dispersion parameters of individual single mode optical fibers, and compare theoretical valuse with those measrued by double demodulation method. Calculated values are coincident with measured ones reasonably. The standard deviation is 0.77-1.28nm for zero dispersion wavelength and 0.56-0.75PS/km.nm2 for dispersion slope. The standard deviation of zero dispersion wavelength is inverse proportional to the optical fiber lenght.

• Proceedings of the Optical Society of Korea Conference
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• 2004.07a
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• pp.208-209
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• 2004

We propose a dynamic controlling system of dispersion compensation by uisng electromagnetically inudced grating. This has potential applications for active control of dispersion compensation in a broad specteal range of WDM fiber-optic communication channels.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1939-1940
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• 2002

Numerical simulation for effect of chirp on PMD and PDL was accomplished. we assumed two uniform fiber concatenation with both polarization mode dispersion and polarization-dependent loss. We showed that polarization mode dispersion is increased with chirp parameter and polarization-dependent loss is decreased with chirp. And we accomplished mathematical analysis.

• Journal of the Optical Society of Korea
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• v.3 no.1
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• pp.20-22
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• 1999

We present numerically simulated results on stabilities of optical soliton transmission in highly-dispersion-perturbed optical fiber systems. We have found that the perturbation of dispersion along the transmission line does not significantly degrade stability of soliton transmission as long as the average soliton concept is obeyed.