• Journal of KSNVE
• /
• v.10 no.3
• /
• pp.536-550
• /
• 2000

Inversitgated in this study are the modal characteristics of the eccentric cylindrical shells with fluid-filled annulus. Theoretical method is developed to find the natural frequencies of the shell using the finite Fourier expansion and their results are compared with those of finite element method to verify the validation of the method developed. The effect of eccentricity on the modal characteristics of the shells is investigated using a finite element modeling.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.15 no.4
• /
• pp.217-222
• /
• 2015

Longitudinal transmission-line modal theory is applied to analyze the guiding mode characteristics along 1D & 2D grating patterns of plasmonic grating-assisted directional couplers (P-GADC) based on silicon waveguide. By defining supermodes amenable to rigorous analytical solutions and interference between even and odd modes, the field distributions of TE modes for each grating patterns are evaluated. The numerical result reveals that the field distribution with maximum coupling efficiency occurs at P-GADC composed by square grating pattern. That is, it reveals at a minium gap condition of grating period $d_{min}=8.8{\mu}m$ different from conventional phase-matching condition of GADC.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.3
• /
• pp.515-522
• /
• 1994

The radiation characteristics of the conical corrugated feed horn are analyzed by the Gaussian beam mode theory. the electric field over the aperture can be expanded in terms of a set of Gaussian-Laguerre modes. It is proved that these modes are the solutions of the wave epuations for the paraxial approximation. A method, using the sum of the mode expansion coefficients instead of calculation only the fundamental mode, is presented in order to reduce the radiation pattern error. For illustrative examples, the radiation patterns of the corrugated horn antenna operting over C, Ku, and mm-wave band are calculated. Our results agree well with the results obtained by the vector potential method over each band, and also agree well with the measured value at 6.175GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.3
• /
• pp.301-310
• /
• 2004

In this paper, a compact dual-mode filter structure without coupling gaps is proposed. The novel design is achieved by embedding a pair of equal crossed slots and spur-lines. Without coupling gaps between feed lines and patch resonator, the new filter can provide low insertion loss. It is found that this design has wide coupling range for dual-mode operation. It means that these characteristics of the proposed filter can reduce uncertainty in fabrication. By using two PIN diodes mounted inside a pair of spur-lines, the proposed structure works as a switchable filter. Also, it has a size reduction of about 34.7 %, compared with conventional dual-mode filters.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.277-284
• /
• 2017

This study is the results of the analytical research for a dual-model scramjet engine flowpath which is included inlet, isolator, combustor, and nozzle. To design a dual-mode scramjet engine and to investigate its performance, the performance analysis models and tools are required to develope for aerodynamic, thermodynamic characteristics, propulsion, and total system. Therefore, analysis models for air inlet, isolator, supersonic combustor, and nozzle of a dual-mode scramjet engine were accomplished, the performance characteristics of a dual-mode scramjet engine is investigated with using the developed analysis tools.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.16 no.2
• /
• pp.165-170
• /
• 2016

Nano-scale power splitter based on curved plasmonic waveguides are designed by utilizing the multimode interference (MMI) coupler. To analyze easily the adaptive properties of plasmonic curverd multimode interference coupler(PC-MMIC), the curved form transforms equivalently into a planar form by using conformal transformation method. Also, effective dielectric method and longitudinal modal transmission-line theory are used for simulating the light propagation and optimizing the structural parameters at 3-D guiding geometry. The designed $2{\times}2$ PC-MMIC does not work well for quasi-TM mode case due to the bending structure, and it does not exist 3dB coupling property, in which the power splitting ratio is 50%:50%, for quasi-TE mode case. Further, the coupling efficiency is better when the signal is incident at channel with large curvature radius than small curvature radius.

• Composites Research
• /
• v.23 no.4
• /
• pp.21-27
• /
• 2010

In most engineering structures, fracture often takes place due to fatigue. Therefore, many studies about the effect of the various mode-mixities on fatigue characteristics have been performed. However, most of the former studies only address metal/metal interfaces or delamination of composite. In this study, the fatigue characteristics of composite/metal interfaces are investigated. The fatigue tests were performed using single leg bending(SLB)specimens that comprise composite and steel bonded to each other using co-cure bonding method. This paper focuses on fatigue characteristics depending on different mode ratios$(G_{II}/G_T$. The overall results obtained in this study show that the crack propagation rate increases with the mode II loading component.

• Korean Journal of Optics and Photonics
• /
• v.20 no.6
• /
• pp.339-345
• /
• 2009

The high power and single mode vertical cavity surface emitting laser(VCSEL)s with photonic crystal structures have been proposed and fabricated by reducing substantially the hole numbers used in the photonic crystal structures. It is found that only six holes enable VCSELs to operate a single mode and the reliability can be enhanced by filling the holes with polyimide. The single mode lasing characteristics were analyzed by varying the oxide aperture and the hole diameter in photonic crystal structures. As a result, the single mode lasing can be stably obtained in the photonic crystal vertical cavity surface emitting lasers.

• Proceedings of the Optical Society of Korea Conference
• /
• 1991.07a
• /
• pp.71-75
• /
• 1991

Ti-Sapphire 레이저는 광대역 특성 때문에 최근 색소레이저의 대체 레이저로써 활발히 연구되고 있다. 본연구에서는 고분해 분광학의 광원으로 이용하기 위해 설계 제작한 단일 종모드로 동작하는 Ti:Sapphire 레이저의 특성에 대해 논한다.

• Proceedings of the Korea Contents Association Conference
• /
• 2013.05a
• /
• pp.29-30
• /
• 2013

차세대 전자 소자용 전송 선로로 사용될 수 있는 나노 원기둥 배열의 분산 관계 특성을 모드 정합법을 사용하여 계산하였다. 서로 떨어진 나노 원기둥 배열에도 배열이 놓인 방향으로 전자파 모드가 형성되는 것을 수치 해석 결과로 제시한다. 또한 나노 원기둥 배열에 생기는 전기장의 분포 특성도 제시한다.