• Current Optics and Photonics
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• v.6 no.2
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• pp.196-201
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• 2022

Collagen fibers tens of nanometers in size, which constitute most of the corneal volume of the human eye, are layered in a uniform direction, and adjacent fiber layers are arranged at an angle of 90° to each other. According to the results of this study, the transmittance at 45° of interlayer rotation angle is highest, and higher than that of the 90° body structure. The transmittance is examined, concerning the polarization state of the incident light; circularly polarized light case shows higher transmittance than linearly polarized. Through this, a simulation to confirm the deformed structure of collagen fibers, which show higher transmittance than the anatomical structure of the cornea, is attempted.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.5 s.96
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• pp.526-533
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• 2005

In this paper, the miniaturized the linear polarization and the circular polarization microstrip antennas, which are the two ends in the resonance length direction or all the four-ends were folded are designed and fabricated at the resonant frequency of 1.575 GHz(fur GPS system). For the linear polarization microstrip antenna, the antenna was bent. downward so that the visible length(=L) was reduced by $31.7\%(\varepsilon_r=1.06)$. The folded antenna was folded toward the center of the antenna once again. In this case, the visible length reduction rate, gain, -10 dB bandwidth, E-plane and H-plane HPBW were $73.9\%$, 5.12 dBd, $64MHz(4\%),\;151^{\circ}\;and\;79.2^{\circ}$, respectively. For the circular polarization microstrip antenna, the folded structure of the linear polarization antenna was applied to all the few directions. For the most efficiency the folded bottom surfaces were designed in a triangular shape. In this case, the visible area reduction rate, gain, -10 dB bandwidth, and HPBW in horizontal polarization of the z-x plane and the z-y plane were $71.5\%,\;3.96dBd,\;84MHz(5.3\%),\;80.6^{\circ}\;and\;82.1^{\circ}$, respectively. Therefore, we have confirmed that the folded structure is suitable fer the miniaturization of the microstrip antenna.

• The Journal of Engineering Geology
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• v.5 no.1
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• pp.59-74
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• 1995

It is well known that the hypocentral parameters inside the seismic array are well determined using HYPO71PC Programs. These programs, however, do not woik well for the non-evenly distribution of the seismic stations and/or the seismic events outside the seismic array. Furthermore it is very difficult to determine the exact locations of small events in North Korea since there is no seismological data exchange between South and North Koreas. We used the polarization method of the single-station with 3-component in addition to HYPO71PC(IASPEI's Program) in order to determine the source parameters of shallow-focus earthquakes outside the seismic array. First of all, we tested the interior events of the Uisung earthquake, April 14, 1991 and the Mt. Keyryong earthquakes, Feorirary 12, 1994, and two exterior events of W. Pyoungyang earthquake, Noventer 12, 1992, and Yellow Sea earthquake, July 26, 1994 to investigate the convergence and divergence to calculate the source parameters. We have found that the source determination outside the seismic array never converges to the exact location whereas the any events inside the array quickly converge to the exact location. The seismic events outside the array such as two events Vladivostok and East Sea, and the Yellow Sea event are more accurately determined using the polarization method. Estimating the source azimuth is carried out by estimating the polarization direction of the interesting phases and the range estimate is made frum the relative timing of different phases. The polarization method is verified by fmding that the estimates of azimuths and incidence angles by the polarization method are identical with those of the synthetic seismograms of the modellings using the generator program.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.12
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• pp.1316-1324
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• 2009

In this paper, cross-aperture coupled microstrip circular polarization antenna is proposed for 5.8 GHz WLAN(Wireless Local Area Network). A single antenna consists of square patch and slots are located in series feed line with $\lambda_g$/4 phase different which make current direction maximum and minimum repeatedly to generate RHCP(Right Handed Circularly Polarization). We are proposed new structure that removed the section which intersected at a right angle and were composed to four separated slots. The proposed cross slots reduce back lobe of radiation pattern and improve antenna gain. Impedance bandwidth of the manufactured $2\times2$ array antenna is from 5.67 to 5.95 GHz and the maximum radiation gain is 10.59 dBi.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.2
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• pp.113-121
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• 2013

In this paper, quadruple polarized antenna system with a reconfigurable feeding network is presented. The proposed antenna system consists of the reconfigurable feeding network for fourth polarization such as vertical/horizontal linear polarization and right-handed/left-handed circular polarizations or 45 degree tilted vertical/horizontal linear polarization and patch antenna to receive the signals with various polarizations. In order to receive a signal in any direction, the proposed antenna is designed by electrical switches for reconfigurable polarization. The insertion loss of the designed feeding network in the proposed antenna system is approximately 1.2 dB. The measured 3 dB axial bandwidth and gain of the proposed antenna are about 2 % and 4 dBi(c).

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.65.1-65.1
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• 2016

We present results of long-term multi-wavelength polarization observations of the powerful blazar 3C 279 after its ${\gamma}$-ray flare on 2013 December 20. We followed up this flare by means of single-dish polarization observations with two 21-m telescopes of the Korean VLBI Network, carried out weekly from 2013 December 25 to January 11, and at 22, 43, and 86 GHz, simultaneously. These observations were part of the Monitoring Of GAmma-ray Bright AGNs (MOGABA) program. We Measured 3C 279 total flux densities at 22, 43, and 86 GHz, showing a mild variability of a factor of ${\leq}50%$ over the period of our observations. The spectral index ranged from -0.13 to -0.36 at between 22 and 86 GHz. The degree of linear polarization was in the range of 6 ~ 12 %, and slightly decreased with time at all frequencies. We found Faraday rotation measures (RM) of -300 to $-1200rad\;m^{-2}$ between 22 and 43 GHz, and -800 to $-5100rad\;m^{-2}$ between 43 and 86 GHz. The RM values follow a power law ${\mid}RM{\mid}{\propto}{\nu}^{\alpha}$, with a mean ${\alpha}$ of 2.2, implying that the polarized emission at these frequencies travels through a Faraday screen in or near the jet. We conclude that the regions emitting polarized radio emission may be different from the region responsible for the 2013 December ${\gamma}$-ray flare, and that these regions are maintained by the dominant magnetic field perpendicular to the direction of the radio jet at milliarcsecond scales.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.502-514
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• 1998

The purpose of this study is to observe the corrosion characteristcs of four dental amalgams(CAULK FINE CUT, CAULK SPHERICAL, DISPERSALLOY, TYTIN) and to determine a function of chloride concentration through the anodic polarization curve obtained by using a potentiostat. After each amalgam alloy and Hg being triturated, the triturated mass was inserted into the cylinderical metal mold, and condensed by hydrolic pressure. Each specimen was removed from the metal mold. 24 hours after condensation, specimens were polished with the emery paper and stored at room temperature for 6 months. The anodic polarization curves were employed to compare the corrosion behaviours of the amalgam m KCl and KCl-NaCl solution, which had chlonde concentration of 0.4 g/l, 0.8 g/l, 1.2 gil, and 1.6 gil at $37^{\circ}C$ with 3-electrode potentiostat. After the immersion of specimen in electrolyte for 1 hour, the potential scan was begun. The potential scan range was - 1500mV ~+800mV(vs. S.C.E.) in the working electrode and the scan rate was 50mV/sec. The results were as follows, 1. The corrosion potential. the potential of anodic current peak, and transpassive potential in the solution of high chloride concentration shifted to more cathodic direction than those in the solution of low concentration, and the current density in the solution of high chloride concentration was higher than that in the solution of low concentration. 2. The corrosion potential, the potential of anodic current peak, and transpassive potential for CAULK FINE CUT amalgam were the most cathodic among the others, and the current density were the highest among the others. 3. In the solution of low chloride concentration, the corrosion potential, the potential of anodic current peak, and transpassive potential for DISPERSALLOY were the most anodic among the others, however in the solution of high chloride concentration, those for TYTIN were the most anodic among the others. 4. The anodic polarization curve for CAULK SPHERICAL was similar to that for high copper amalgams.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.396-412
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• 1997

The purpose of this study is to observe the corrosion characteristics of five dental amalgams(CAULK FINE CUT, OPTALLOY II, DISPERSALLOY, TYTIN, and VALIANT) in the solutions with fluoride compound through the anodic polarization curve obtained by using a potentiostat. After each amalgam alloy and Hg being triturated, the triturated mass was inserted into the cylindrical metal mold, and condensed by hydraulic pressure(160 kg/$cm^2$). Each specimen was removed from the metal mold. Specimens were polished with the silicone carbide grinding paper 24 hours after condensation and stored at room temperature for 1 week. The anodic polarization curves were employed to compare the corrosion behaviours of the amalgams in 0.9 % saline solution and in the saline solutions with 2.2 ppm, 0.05 %, 2 % NaF, and 8 % $SnF_2$ at $37^{\circ}C$ with 3-electrode potentiostat. After the immersion of specimen in electrolyte for 30 minutes, the potential scan was begun. The potential scan range was -1500m V to + 800m V(vs. S.C.E.) in the working electrode and the scan rate was 50 mV/sec. The results were as follows, 1. The corrosion potential, the potential of anodic current peak, and transpassive potential in the saline solutions with NaF shifted to lower direction than those in normal saline solution, and the current density in the saline solutions with NaF was higher than that in normal saline solution. The differences were increased as the concentrations of NaF became higher. 2. The corrosion potential and transpassive potential in the saline solution with $SnF_2$ shifted to higher direction than those in normal saline solution, and the current density in the saline solution with $SnF_2$ was higher than that in normal saline solution after the corrosion potential. The anodic polarization curves in the saline solution with $SnF_2$ had no outstanding anodic current peak. 3. The corrosion potentials for high-copper amalgams were much higher than those for CAULK FINE CUT and OPTALLOY II in normal saline solution, but, as the concentrations of fluoride compound became higher, the differences in corrosion potentials between them were decreased. The corrosion potentials had the similarity in the saline solution with 2% NaF or 8% $SnF_2$. 4. The current density for TYTIN was the lowest among the others in normal saline solution and in the saline solution with 2.2 ppm or 0.05 % NaF. 5. There was no significant difference in current density between Pd-enriched VALIANT and other high-copper amalgams.

• Corrosion Science and Technology
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• v.13 no.1
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• pp.20-27
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• 2014

The structures of reinforced concrete has been extensively increased with rapid development of industrial society. Futhermore, these reinforced concretes are easy to expose to severe corrosive environments such as sea water, contaminated water, acid rain and seashore etc.. Thus, corrosion problem of inner steel bar embedded in concrete is very important in terms of safety and economical point of view. In this study, multiple mortar test specimen(W/C:0.4) with six types having different cover thickness each other was prepared and was immerged in seawater solution for five years to evaluate the effect of cover thickness and immersion years to corrosion property of embedded steel bar. And the polarization characteristics of these embedded steel bars was investigated using electrochemical methods such as measuring corrosion potential, cathodic polarization curve, and cyclic voltammogram. At the beginning of immersion, the corrosion potentials exhibited increasingly nobler values with increasing cover thickness. However, after immersed for 5 years, the thicker cover of thickness, the corrosion potentials shifted in the negative direction, and the relationship between corrosion potential and cover thickness was not in good agreement with each other. Therefore, it is considered that the thinner cover of thickness, corrosive products deposited on the surface of the embedded steel bar plays the role as a resistance polarization which is resulted in decreasing the corrosion rate as well as shifting the corrosion potential in the positive direction. As a result, it seemed that the evaluation which corrosion possibility of the reinforced steel would be estimated by only measuring the corrosion potential may not be a completely desirable method. Therefore, it is suggested that we should take into account various parameters, including cover thickness, passed aged years as well as corrosion potential for more accurate assessment of corrosion possibility of reinforced steel which is exposed to partially or fully in marine environment for long years.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.3 no.2
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• pp.3-9
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• 1992

The reponse of the angled two-strip transmission lines illuminated by an external electromagnetic field is estimated by using the circuit concept approach. Calculated terminal voltages reveal convergence to a fixed value as the number of discretization increases. The amplitude patterns of two terminal voltages to all the direction and polarization of the incident field are also calculated.