• Title/Summary/Keyword: Physical optics

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A Hybrid IPO-MoM Technique for Wave Scattering Analysis of Jet Engine (제트 엔진 산란 해석을 위한 하이브리드 IPO-MoM 기법)

  • Lim, Ho;Choi, Seung-Ho;Myung, Noh-Hoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.8
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    • pp.791-796
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    • 2009
  • A hybrid iterative physical optics-method of moments(IPO-MoM) technique is presented for the analysis of jet engine structures which are both electrically large and complex. In this technique, the IPO method is used to analyze smooth inlet region and the MoM method is used to analyze electrically complex region inclusive of blades and hub. It is efficient and accurate by virtue of combining the respective merits of both methods. Numerical results are presented and validated through comparison with Mode-FDTD and measured results.

RCS Numerical Simulation of Stealth Modified Three-Surface Aircraft

  • Cheng, Liangliang;Yue, Kuizhi;Xing, CuiFang;Yu, Dazhao
    • International Journal of Aeronautical and Space Sciences
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    • v.17 no.1
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    • pp.101-108
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    • 2016
  • The RCS characteristics of stealth modified three-surface aircraft are analyzed in this paper. Prototype A is built with CATIA software and the three-dimensional digital models of modified stealth three-surface B and C are also designed based on carrier-based aircraft Su-33; the numerical simulation of RCS characteristics of three-surface aircraft is conducted with RCSAnsys software based on physical optics method and the method of equivalent currents; The following results are obtained by comparative analysis and mathematical statistics: (1) by the use of physical optics method and equivalent electromagnetic current method, the scattering intensity for each part of the model and RCS characteristic of the aircraft can be analyzed efficiently and accurately; (2) compared with model A, the mean RCS value of model B is reduced to 14.1% in forward direction and 48.1% in lateral direction; (3) compared with model A, the mean RCS value of model C decreases to 11.4% in forward direction and 21.6% in lateral direction. The results are expected to provide theoretical basis and technical support to the conceptual design of aircraft and stealth technology research.

Development of QCM dew point sensor and its sensing characteristics study (수정미소저울 노점센서 제작 및 반응특성 연구)

  • Kwon, Su-Yong;Kim, Jong-Chul;Choi, Byung-Il
    • Journal of Sensor Science and Technology
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    • v.15 no.4
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    • pp.269-276
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    • 2006
  • This paper represents development of quartz crystal microbalance (QCM) and usage as a dew point sensor. The temperature of a quartz resonator was controlled precisely from $20^{\circ}C$ to $-30^{\circ}C$ with the ramping rate of $0.1^{\circ}C/s$ by using a custom-made crystal holder housing the quartz resonator associated with a thermoelectric cooler (Peltier cooler), which results in the working range from $15.2^{\circ}C$ to $-24.0^{\circ}C$ based on an accurate holder temperature compensation and temperature effect compensation process. The developed QCM dew point sensor and analysis techniques show very good sensing characteristics at measurement of moist air with the relative humidity from 10 %R.H. to 90 %R.H. generated by a divided-type humidity generator and the dew point temperatures were determined with an accuracy of less than ${\pm}0.18^{\circ}C$, which also showed good agreement with reference values in their error range.

RCS Analysis of Complex Structures Using Object Precision Method (Object Precision 방법을 이용한 복합 구조물의 RCS 해석)

  • Kim, Kook-Hyun;Kim, Jin-Hyeong;Cho, Dae-Seung
    • Journal of the Society of Naval Architects of Korea
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    • v.42 no.2 s.140
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    • pp.159-164
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    • 2005
  • Monostatic RCS analysis of complex structures has been done with a combined method of physical and geometric optics, commonly applied to high frequency electromagnetic backscattering problems. In the analysis, the complex structure is modeled as a number of flat surfaces and the RCS of whole structure is calculated by summing RCS of each surface, which can be obtained from an analytical solution of flat surface phase integral derived from physical optics. The reflected and hidden surfaces are searched by an object precision method based on adaptive triangular beam method, which can take account for effects of multiple reflections and polarizations of electromagnetic wave. The validity of the presented RCS analysis method has been verified by comparing with exact solutions and measured data for various structures.

Physical and Optical Properties of Hydrophilic Tinted Lens Materials with the Fluoro-substituted Aniline Group

  • Park, Se-Young;Lee, Min-Jae;Sung, A-Young
    • Journal of Integrative Natural Science
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    • v.8 no.1
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    • pp.60-66
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    • 2015
  • The physical and optical properties of polymers with 2-fluoroaniline and 4-fluoroaniline added, which can be used for hydrophilic ophthalmic lenses, were investigated in this study. The UV-blocking properties of 2- and 4-fluoroaniline were also investigated by measuring their UV transmissibility. 2- and 4-Fluoroaniline were used as additives for the basic combination of HEMA, 5% AA, and 1% MMA, and the materials were copolymerized with EGDMA as the cross-linking agent and AIBN as the initiator. The refractive index, water content, optical transmittance, tensile strength, and contact angle were measured to evaluate the physical properties of the produced hydrogel lens. The measured physical properties of the hydrogel contact lens produced with the copolymerized polymer showed a refractive index of 1.425-1.436; a water content of 36.95-44.65%; a visual light transmittance of 66.0-81.0%; a tensile strength of 0.138-0.281 kgf; and a contact angle of $55.02-57.87^{\circ}$. The UV transmissibility was significantly reduced, which indicates that 2-fluoroaniline and 4-fluoroaniline have UV-blocking properties. This study showed that 2- and 4-fluoroaniline are expected to be used as UV-blocking materials in hydrogel ophthalmic lenses whose physical properties, such as their refractive index and water content, do not change.

Polymerization of Contact Lens Materials Using Silicone (Silicone을 이용한 콘택트렌즈 재료의 중합)

  • Kim, Tae-Hun;Ye, Ki-Hun;Kwon, Young-Seok;Sung, A-Young
    • Journal of Korean Ophthalmic Optics Society
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    • v.11 no.2
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    • pp.143-149
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    • 2006
  • The purpose of this study is synthesizing silicone polymer which is used the material of contact lens and solving the problems of water content and light transmittance for gas permeable contact lens. We used NVP, MMA, HEMA monomer for polymerization and EGDMA as cross linking regent. Also, we polymerized with a several formulation arrangement for the best condition as contact lens. After that. we measured water content and light transmittance by each sample which was polymerized. We polymerized the silicone polymer which is simultaneously pursued by the transparent and water content of the material and measured their physical nature of each sample on this study.

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Ultrafast Femtosecond Lasers: Fundamentals and Applications (펨토초 레이저의 원리 및 응용)

  • Kim, Young-Jin;Kim, Yun-Seok;Kim, Seung-Man;Kim, Seung-Woo
    • Journal of the Korean Society for Precision Engineering
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    • v.27 no.6
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    • pp.7-16
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    • 2010
  • Physical fundamentals of ultrashort femtosecond lasers are addressed along with emerging applications for precision manufacturing and metrology. Femtosecond lasers emit short pulses whose temporal width is in the range of less than a picosecond to a few femtoseconds, thereby enabling extremely high peak-power machining with less thermal damages. Besides, the broad spectral bandwidth of femtosecond lasers constructed in the form of frequency comb permits absolute distance measurements leading to ultraprecision positioning control and dimensional metrology.

Influence of Wetting Agents on Physical Properties of Soft Contact Lens (친수성 소프트 콘택트렌즈의 물리적 특성에 미치는 습윤성 재료의 영향)

  • Lee, Min-Jae;Sung, A-Young;Kim, Tae-Hun
    • Journal of Korean Ophthalmic Optics Society
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    • v.19 no.1
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    • pp.43-49
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    • 2014
  • Purpose: The physical and optical characteristics of hydrophilic contact lens polymerized with addition of glycerin and PVP(polyvinylpyrrolidone) in the basic hydrogel contact lens material were evaluated. Methods: This study used glycerin and PVP(polyvinylpyrrolidone) with the cross-linker EGDMA (ethylene glycol dimethacrylate), HEMA (2-hydroxyethyl methacrylate) and the initiator AIBN (azobisisobutyronitrile) for copolymerization. Results: Measurements of the physical characteristics of the copolymerized material including PVP(polyvinylpyrrolidone) showed the refractive index of 1.4382~1.4288, tensile strength of 0.3446~2542 kgf and water content and contact angle of sample showed the increase of 13.49% and decrease of 21.44% independently. And also, the physical characteristics of the copolymerized material including glycerin showed the refractive index of 1.4330~1.4328, tensile strength of 0.2974~0.2854 kgf, water content 35.58~36.53% and contact angle of sample showed the decrease of 37.64%. Conclusions: Based on the results of this study, the produced copolymers is suitable for conventional lens with high wettability. Also, glycerin minimized the changes of water content and refractive index at the same time, increased the wettability of the hydrogel lens materials.

Development of High Spectral Resolution Lidar System for Measuring Aerosol and Cloud

  • Zhao, Ming;Xie, Chen-Bo;Zhong, Zhi-Qing;Wang, Bang-Xin;Wang, Zhen-Zhu;Dai, Pang-Da;Shang, Zhen;Tan, Min;Liu, Dong;Wang, Ying-Jian
    • Journal of the Optical Society of Korea
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    • v.19 no.6
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    • pp.695-699
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    • 2015
  • A high spectral resolution lidar (HSRL) system based on injection-seeded Nd:YAG laser and iodine absorption filter has been developed for the quantitative measurement of aerosol and cloud. The laser frequency is stabilized at 80 MHz by a frequency locking system and the absorption line of iodine cell is selected at the 1111 line with 2 GHz width. The observations show that the HSRL can provide vertical profiles of particle extinction coefficient, backscattering coefficient and lidar ratio for cloud and aerosol up to 12 km altitude, simultaneously. For the measured cases, the lidar ratios are 10~20 sr for cloud, 28~37 sr for dust, and 58~70 sr for urban pollution aerosol. It reveals the potential of HSRL to distinguish the type of aerosol and cloud. Time series measurements are given and demonstrate that the HSRL has ability to continuously observe the aerosol and cloud for day and night.