• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.91-100
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• 1998

Color indexes and effective temperatures for 25 standard stars have been determined as a pilot project which show a relationship between color index and effective temperature in ultraviolet region. The effective temperature was determined by comparing energy distribution curves derived from the IUE low dispersion spectra with Kurucz atmosphere model. The UV color index was deduced by integrating fluxes in $300{\AA}$ interval of the IUE low disperion spectra. The relation between color index and effective temperature in ultraviolet is similar with that of optical region.

• Korean Journal of Optics and Photonics
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• v.18 no.1
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• pp.56-65
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• 2007

The effect of gain dispersion on the self-pulsation (SP) characteristics due to the mode beating of two modes emitted in a multisection DFB laser composed of two complex-coupled DFB sections and a phase control section is investigated. When the peak wavelength, ${\lambda}_{p}$, of the gain spectrum of the DFB section is positioned in the center of the lasing wavelengths or the Bragg wavelengths of the two DFB sections, the maximum SP frequencies are higher and the modulation index has better characteristics compared to those cases for ${\lambda}_{p}$ fixed at the lasing wavelength or Bragg wavelength of one DFB section, when the difference between the Bragg wavelengths of the two DFB sections, ${\Dalta}{\lambda}_{B}$, is varied. When ${\lambda}_{p}$ is positioned in the renter of the Bragg wavelengths of the two DFB sections, the maximum SP frequency is higher and of the modulation index has better characteristics compared to those of the case for ${\lambda}_{p}$ positioned in the center of the lasing wavelengths of the two DFB sections.

• Geomechanics and Engineering
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• v.12 no.3
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• pp.523-539
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• 2017

Clay soils are typical for their swelling properties upon absorption of water during rains and development of cracks during summer time owing to the profile desorption of water through the inter-connected soil pores by water vapour diffusion leading to evaporation. This type of unstable soil phenomenon by and large poses a serious threat to the strength and stability of structures when rest on such type of soils. Even as lime and cement are extensively used for stabilization of clay soils it has become imperative to find relatively cheaper alternative materials to bring out the desired properties within the clay soil domain. In the present era of catastrophic environmental degradation as a side effect to modernized manufacturing processes, industrialization and urbanization the creative idea would be treating the waste products in a beneficial way for reuse and recycling. Bottom ash and ecosand are construed as a waste product from cement industry. An optimal combination of bottom ash-eco sand can be thought of as a viable alternative to stabilize the clay soils by means of an effective dispersion dynamics associated with the inter connected network of pore spaces. A CATIA model was created and imported to ANSYS Fluent to study the dispersion dynamics. Ion migration from the bottom ash-ecosand pile was facilitated through natural formation of cracks in clay soil subjected to atmospheric conditions. Treated samples collected at different curing days from inner and outer zones at different depths were tested for, plasticity index, Unconfined Compressive Strength (UCS), free swell index, water content, Cation Exchange Capacity (CEC), pH and ion concentration to show the effectiveness of the method in improving the clay soil.

• Steel and Composite Structures
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• v.44 no.1
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• pp.17-31
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• 2022

This investigation studies the characteristics of wave dispersion in sigmoid functionally graded (SFG) curved beams lying on an elastic substrate for the first time. Homogenization process was performed with the help of sigmoid function and two power laws. Moreover, various materials such as Zirconia, Alumina, Monel and Nickel steel were explored as curved beams materials. In addition, curved beams were rested on an elastic substrate which was modelled based on Winkler-Pasternak foundation. The SFG curved beams' governing equations were derived according to Euler-Bernoulli curved beam theory which is known as classic beam theory and Hamilton's principle. The resulted governing equations were solved via an analytical method. In order to validate the utilized method, the obtained outcomes were compared with other researches. Finally, the influences of various parameters, including wave number, opening angle, gradient index, Winkler coefficient and Pasternak coefficient were evaluated and indicated in the form of diagrams.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.7
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• pp.245-252
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• 1996

$\lambda$/4 phase-shifted DFB lasers with nonideal grating structure have been studied by using an effective-index transfer matrix method where material dispersion, vwaveguide dispersion and waveguide-structuredependent loss are taken into consideration. Nonideal grating structure in the center phase-shift region does not incur serous degradation of laser characteristics. Phase-shift error from the ideal shift of $\pi$ causes a decrease in the threshold gain difference and lasing wavelength shift and should be less than $\pi$/4 when residual facet reflectivity is 0.7%. also, positional error of the phase-shift should be less than 9% of the cavity length in order for the threshold gain difference to be decreased less than 10%.

• Electrical & Electronic Materials
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• v.8 no.3
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• pp.332-339
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• 1995

In this paper, it was investigated the guided field intensity distribution of the channel in the silver & potassium ion-exchange glass-waveguide. The guided field intensity distribution analysis of ion-exchange glass-waveguide was based on the combination of the WKB dispersion relationship method with a Gaussian distribution function of refractive index profile and the Field Shadow method to the modeling of the channel waveguide. As the results of the channel waveguide modeling, it was represented 2-dimensional and 3-dimensional field distribution of ion-exchange glass waveguide.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1834-1836
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• 1998

The characteristics of dispersion compensation in uniform fiber grating is studied according to grating length, the refractive index modulation depth, and Gaussian window parameter(G). A 50cm-long uniform grating apodized by Gaussian function(G=10) with bandwidth of ${\sim}0.8nm$ and small noise is designed.

• Current Optics and Photonics
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• v.2 no.3
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• pp.226-232
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• 2018

We propose a triangular-multicore hollow optical fiber (TMC-HOF) design for uncoupled mode-division and space-division multiplexing. The TMC-HOF has three triangular cores, and each core has three modes: $LP_{01}$ and two split $LP_{11}$ modes. The asymmetric structure of the triangular core can split the $LP_{11}$ modes. Using the proposed structures, nine independent modes can propagate in a fiber. We use a fully vectorial finite-element method to estimate effective index, chromatic dispersion, differential group delay (DGD), and confinement loss by controlling the parameters of the TMC-HOF structure. We confirm that the proposed TMC-HOF shows flattened chromatic dispersion, low DGD, low confinement loss, low core-to-core crosstalk, and low crosstalk between adjacent modes. The proposed TMC-HOF can provide a common platform for MDM and SDM applications.

• Journal of Korean Society of Steel Construction
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• v.15 no.2
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• pp.147-157
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• 2003

The application in steel structures is increasing the mill sheet for the weathering steels by minimum maintenance cost in a life cycle cost. These have been collected and statistically analyzed to investigate chemical compositions, mechanical properties, weldability indices, weathering index and impact absorbed energy. From this study, although the band of dispersion in chernical compositions, mechanical properties and impact absorbed energy of the weathering steels appeared a little larger, the results revealed that these values have adequately satisfied the standard values of the Korean Standard. Furthermore, it was found that the weldability indices and the weathering index for the weathering steels have respectively satisfied the value prescribed by the Japanese Highway Specification and ASTM.

• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.315-319
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• 2014

Mean densities of two-spotted spider mite (TSM), Tetranichus urticae Koch adults from January to April in 2014 to investigate the occurrence and dispersion pattern of T. urticae on purpose of developing a monitoring method in the strawberry PVC house. Difference of density of T. urticae adult on middle and both side of leaf wasn't significantly. Density of T. urticae in investigation at different furrows and investigating points was the highest at the right and left sides of a furrow in strawberry PVC house. In results of comparing the dispersion incides of Taylor's power law (TPL) with Iwao's patchiness regression (IPR), TPL described better mean-relationship for the dispersion indieces compared to IPR. Slopes and intercepts of TPL from leaf samples did not differ among surveyed regions. Also, Distribution of T. urticae in a strawberry PVC house was the gravitation of the distribution because b and ${\beta}$ values of TPL and IPR was bigger than 1.