• Title/Summary/Keyword: angle dependence

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Saturation Characteristic of Iron Core Dependent on Fault Angle in a Flux-Lock Type SFCL (자속구속형 초전도 사고전류제한기의 사고각에 따른 철심의 포화특성)

  • Kim, Jae-Chul;Lim, Sung-Hun
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.10
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    • pp.29-34
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    • 2007
  • The fault current limiting characteristics of a flux-lock type superconducting fault current limiter(SFCL) according to fault angles were investigated. From the electrical equivalent circuit with the magnetization branch, the inner magnetic flux of this SFCL due to fault angles was induced and its effect on the limited fault current was analyzed. From the fault current limiting experiments, the exciting current, which described the saturation of the iron core, was calculated and its dependence on the fault angle was analyzed. Before the fault happened, the exciting current did not happen, that it kept zero value. However, after the fault happened, the exciting current flowed and, the exciting current in case of the additive polarity winding showed higher value than for the case of the subtractive polarity winding. The analysis results were compared with the experimental ones, and experimental results agreed with the analysis ones.

Small-Angle Neutron Scattering Study of the Structure of Micelles Formed by a Polystyrene-Poly(ethylene oxide) Diblock Copolymer in Aqueous Solution (수용액 내 폴리스티렌-폴리에틸옥사이드 이중블록공중합체 미셀 구조에 대한 소각중성자산란 연구)

  • Kang, Byoung-Yook;Choi, Mi-Ju;Hwang, Kyu-Hee;Lee, Kwang-Hee;Jin, Byoung-Suk
    • Polymer(Korea)
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    • v.33 no.5
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    • pp.485-489
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    • 2009
  • The temperature dependence of the structure of micelles formed by a deuterated polystyrene-poly(ethylene oxide) diblock copolymer (dPS-PEO) in heavy water were investigated with small-angle neutron scattering (SANS). SANS data were analyzed using the hard-sphere structure factor in combination with the form factor of a core-shell model. The micelle aggregation number and corona radius were obtained from the fits to the SANS data. The micelle aggregation numbers varied with temperature from 229 at 25C25C to 240 at 45C45C, with a corresponding increase in the core radius. However, the shell thickness of micelles decreased with increasing temperature from 6.2 to 5.8 nm. These structural changes of micelles might be ascribed to the decrease in the hydration volume per hydrophilic group in the corona because of the increase in hydrophobicity of the PEO block with increasing temperature.

Properties of indium tin oxide thin films prepared by ion assisted deposition at room temperature (상온 이온 보조 증착된 ITO 박막의 특성)

  • 이임영;최상대;이기암
    • Korean Journal of Optics and Photonics
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    • v.13 no.3
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    • pp.204-208
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    • 2002
  • We investigate the dependence of indium tin oxide (ITO) thin films on the mixing ratio of Ar:O22 produced by an ion-gun and O2O2 injected inside the divergence angle of the ion-beam to optimize their sheet resistance and transmittance. The substrate is placed outside the divergence angle, and the films are grown by ion mixing with ITO evaporated at room temperature. From the XRD measurement ITO films are found to be amorphous. ITO thin films show the highest transmittance of 85% at 3××1055 Torr of 022 and Ae:O22 ratio of 40:60, and the smallest sheet resistance of 132 ΩΩ/at 1×105 Torr of O2 and As:O2 ratio of 40:60.

Construction of a Data Bank for Acoustic Target Strength with Fish Species, Length and Acoustic Frequency for Measuring Fish Size Distribution (어류 체장의 자동 식별을 위한 어종별, 체장별 및 주파수별 음향 반사 강도의 데이터 뱅크 구축)

  • LEE Dae-Jae;SHIN Hyeong-Il
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.38 no.4
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    • pp.265-275
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    • 2005
  • A prerequisite for deriving the abundance estimates from acoustic surveys for commercially important fish species is the identification of target strength measurements for selected fish species. In relation to these needs, the goal of this study was to construct a data bank for converting the acoustic measurements of target strength to biological estimates of fish length and to simultaneously obtain the target strength-fish length relationship. Laboratory measurements of target strength on 15 commercially important fish species were carried out at five frequencies of 50, 70, 75, 120 and 200 kHz by single and split beam methods under the controlled conditions of the fresh and the sea water tanks with the 389 samples of dead and live fishes. The target strength pattern on individual fish of each species was measured as a function of tilt angle, ranging from 45 (head down aspect) to +45 (head up aspect) in 0.2 intervals, and the averaged target strength was estimated by assuming the tilt angle distribution as N (5.0,15.0). The TS to fish length relationship for each species was independently derived by a least-squares fitting procedure. Also, a linear regression analysis for all species was performed to reduce the data to a set of empirical equations showing the variation of target strength to a fish length, wavelength and fish species. For four of the frequencies (50, 75, 120 and 200 kHz), an empirical model for fish target strength (TS, dB) averaged over the dorsal sapect of 602 fishes of 10 species and which spans the fish length (L, m) to wavelength (\Lambda,\;m)$ ratio between 5 and 73 was derived: TS=19.44Log(L)+0.56Log(Λ)30.9,(r2=0.53).

Optical information storage using diffraction properties of volume hologram in Fe-LiNbO3 crystal (Fe-LiNbO3결정에서 부피형 홀로그램의 회절특성을 이용한 광정보 저장)

  • An, Jun-Won;Kim, Nam;Lee, Kwon-Yeon
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.35D no.6
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    • pp.63-71
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    • 1998
  • In this paper, we experiment the characteristics of coupling coefficient, gain, diffraction efficiency and dependence of time determined by TWM(Two-Wave Mixing), using Fe-LiNbO3 crystal(doped with 0.015Wt.%). From these results, we proposed to apply for optical memory application. The highest coupling angle of 14。 and maximum coupling coefficient of 6.9cm1 / are obtained at 514.5nm wavelength. Also, maximum diffraction efficiency is 54.13% when intensity ratio and writing beam incident angle are 0.1 and 14o, respectively. After fixing process, diffraction efficiency is 21.4%. As an example, we demonstrated the writing and reconstruct optical data using spatial light modualtor and angular multiplexing in most optimal condition.

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Spectropolarimetric Signals of Comet 2P/Encke During Its 2017 Apparition

  • Kwon, Yuna Grace;Ishiguro, Masateru;Kuroda, Daisuke;Kawabata, Koji S.;Nakaoka, Tatsuya;Kawabata, Miho;Uemura, Makoto;Shinnaka, Yoshiharu;Akitaya, Hiroshi;collaboration, OISTER
    • The Bulletin of The Korean Astronomical Society
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    • v.42 no.2
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    • pp.49.1-49.1
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    • 2017
  • Comets are one of the most primordial solar system objects that hold the information of the early days of solar system formation inside their nuclei. Orbiting the Sun, they spew such ancient materials that have been buried for many years, creating dust and gas comae. Cometary dust grains absorb and scatter sunlight radiating the continuous light, while gas molecules form the line emissions. Eachof the comets has its own light patterns, which depends on the physical and chemical properties of the dust and gas components. In this regard, spectropolarimetrycan be a powerful tool to study the properties of cometary constituents free from contamination of each other. This methodology offers a series of information on the polarization degrees of the dust and gas components as well as on wavelength dependence of the polarization degree and polarization angle of cometary dust simultaneously. Herein, we will report the results of the spectropolarimetric study of comet 2P/Encke, which is one of the well-known objects for its shortest orbital period and its prominent aging signals. We performed a spectropolarimetric observation of comet 2P/Encke in its inbound orbit using the Higashi-Hiroshima Optical and Near-Infrared Camera (HONIR) at the Higashi-Hiroshima Observatory, Japan, on UT 2017 February 21 at high phase angle of =75.7 deg. Ourstudy of this interesting comet is the first and only one done through spectropolarimetry in a referred publication. We will discuss the most recent polarimetric results of our study in terms of 2P/Encke' scurrent evolutionary status.

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Highly Efficient Trans-Reflective Color Filters Incorporating TiO2-MgF2 Multilayer Stacks

  • Shrestha, Vivek Raj;Park, Chul-Soon;Koirala, Ishwor;Lee, Sang-Shin;Choi, Duk-Yong
    • Journal of the Optical Society of Korea
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    • v.19 no.6
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    • pp.566-574
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    • 2015
  • We report for the first time highly efficient trans-reflective color filters capable of demonstrating coloration in both transmission and reflection modes by taking advantage of a multilayer stack consisting of MgF2 and TiO2 used respectively as the low and high index materials. In order to enable such trans-reflective performance, securing an optimal stop band assuming an appropriate bandwidth within the visible regime is pivotal, which was realized by tailoring the thicknesses and the numbers of TiO2-MgF2 bi-layers. Three devices were designed through rigorous simulations and developed via e-beam evaporation to demonstrate vivid blue, green, and red colors in the reflection mode, and yellow, magenta, and cyan colors in the transmission mode, featuring an enhanced efficiency exceeding 90% under normal incidence. The color performance of the filters was examined by referring to the chromaticity coordinates of the transmission and reflection spectra, alongside photographed color images. The dependence of the performance on the angle of incidence was explored with respect to incident polarization, indicating that a transmission surpassing 60% could be stably maintained up to an angle of 75°. Polarization independent transfer characteristics were especially achieved for the normal incidence. The proposed devices may be readily extended to other spectral regimes by adjusting the thicknesses of the films.

A Polarimetric Study of Long-Period Comet C/2013 US10 (Catalina) and Estimation of Its Gas Contamination in Optical and Near-Infrared Wavelengths

  • Kwon, Yuna Grace;Ishiguro, Masateru;Kuroda, Daisuke;Hanayama, Hidekazu;Kawabata, Koji S.;Akitaya, Hiroshi;Itoh, Ryosuke;Nakaoka, Tatsuya
    • The Bulletin of The Korean Astronomical Society
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    • v.41 no.1
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    • pp.48.1-48.1
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    • 2016
  • Polarimetric study of light scattering from cometary dust particles can provide us opportunity to decipher their characteristics, such as sizes, structures, compositions of dust grains, etc. Herein, we present the results of our polarimetric study of long-period comet, C/2013 US10 (Catalina), in optical and near-infrared wavelengths which appeared at large phase angle (52.7 degrees) around the mid-December, 2015. We performed polarimetric and spectroscopic observations with HONIR, attached to the 1.5-m telescope at Higashi-Hiroshima Observatory, on UT 2015 December 17-18 and also obtained optical imaging data sets by the Ishigakijima Astronomical Observatory (IAO) and Okayama Astrophysical Observatory (OAO) taken between 2014-2015. By measuring the intensities of gas emission lines with respect to dust continuum and considering transmittance of each filter, we estimated that the percentages of gas contamination are approximately 10 percents in RC-band and 3 percents in IC-band. With these results, we derive the degree of linear polarization scattered solely from dust components in the coma. At this presentation, we will compare the phase-angle dependence of the degree of linear polarization with those of previous archive data in a wide coverage of wavelengths from RC-band to KS-band. Finally, we are supposed to discuss the spatial variations in polarization within the coma.

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Research on Changes in Short Circuit Current of C-Si Solar Cell by Charge Density Waves (전하밀도파 이론으로 결정질 태양전지의 입사각에 따른 단락전류밀도 변화 연구)

  • Seo, Il Won;Koo, Je Huan;Yun, Myoung Soo;Jo, Tae Hoon;Lee, Won Young;Cho, Guang Sup;Kwon, Gi Chung
    • Journal of the Korean Vacuum Society
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    • v.22 no.4
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    • pp.218-224
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    • 2013
  • We measure solar currents transformed from quantum efficiency as a function of incident angles of solar lights. According to conventional models for solar cells, solar currents can be induced when electrons are separated into electrons and holes in the presence of incident solar lights. On the contrary, solar currents can be possible at the time when pinned charge density waves go beyond the pinning potential barrier under the influence of incident solar beams suggested by some authors. In this experiment, measured solar currents and our theory are in good correspondence to confirm the angle dependence of solar lights.

Study of the Dependence of the Electric Potential on Surface Plasmon Resonance Characteristics (금속 표면의 전위가 표면 플라즈몬 공명 특성에 미치는 영향에 대한 연구)

  • Jeong, Intae;Kwon, Jooseong;Park, Young June
    • Korean Journal of Optics and Photonics
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    • v.25 no.2
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    • pp.95-101
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    • 2014
  • When voltage is applied on the metal layer of a surface plasmon resonance (SPR) sensor, electric field excitation causes charge accumulation on the metal surface. This alters not only the optical properties of the metal but also the SPR angle. In this study we investigate this effectby performing experiments using solutions of various pH values, and we obtain the relation between total surface charge and SPR angle. The curves for the various pH conditions become coincident. We compare our results to those from an earlier space charge layer (SCL) model, and suggest a modified SCL model which explains our result well. This result will be useful in applications of SPR sensors, and in studying the optical properties of thin metal layers.