• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.8
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• pp.1399-1406
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• 2000

The exact electromagnetic field in cylindrical cavity with concentric dielectric rod is analyzed. Resonant frequency of dielectric loaded cavity is calculated by analyzing the characteristic equation. The characteristic equation is solved by using the ContourPlot graph of Mathematica. As the result of comparing calculation value and experimental value of resonant frequencies, we know that the field representation of traveling mode is exact.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1269-1270
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• 2015

외부에서 발생되는 전자파가 특정 구조물 내에 침투하는 경우, 특히 구조체가 도체로 이루어 졌을 때, 구조체의 크기에 따른 특정 주파수가 공진을 일으켜 내부 PCB(Printed Circuit Board), 회로 등에 악영향을 미친다. 본 논문에서는 개구면이 존재하는 공진기에 전자기파가 입사되는 상황을 모드매칭(MM: Mode Matching)을 이용해서 해석한다. 이때 외부 전자파로 인해 개구면에 생기는 새로운 소스를 표면 등가 이론(Surface equivalence theorem)을 이용하여 등가 자기전류로 모델링하여, 공진기 내 외부의 전자기장을 구한 후 개구면에서 접선성분의 경계조건을 적용시켰다. 본 논문에서 사용된 계산식의 검증을 위해 3차원 유한 요소법(FEM: Finite Element Method)기반의 프로그램인 HFSS를 이용 하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.535-540
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• 2004

In this paper, We proposed a rectangular slot antenna with CPW feeder. Slot antennas fed by CPW are attractive due to the simple fabrication simplicity and ease of integration with active devices. This antenna consists of two parts, inner patch and outer patch to realize wide-band antenna by multi-frequency. Also, We fabricated a proposed rectangular slot antenna, confirm characteristics of multi-frequency by tuning antenna parameters, inner antenna's location and size. The experimental results show that each resonant frequency of a fabricated antenna is measured at almost 1, 9GHz, 2.8GHz, 3, 5GHz, 4, 9GHz. In radiation patterns each resonant frequency, radiation pattern 4-th resonant frequency is the same ad that of TM11 in patch antenna. Therefore, the experimental and theoretical results shows that a proposal rectangular slot antenna have triple resonant frequencies.

• The Journal of the Acoustical Society of Korea
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• v.38 no.1
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• pp.67-72
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• 2019

In this study, we investigate the echo reduction performance of miniaturinzed Helmholtz resonators using smaller than wavelength acoustic metamaterial structures. The Helmholtz resonators are formed using air structures which exhibit large impedance mismatch with the surrounding underwater environment. Using the multi-physics software package, we find that significant reduction in the sonar signature is expected and frequency tailoring is possible by controlling the degree of space coiling and inner volume of the resonators. We find that for the basic Helmholtz resonators, up to 7 dB reduction in echo is expected at 10,000 Hz while when the miniaturized Helmoholtz resonators are used, up to 14 dB reduction in echo is expected at 5,000 Hz. In addition, frequency tailoring is demonstrated by varying the internal volume of the Helmholtz resonators and broadband characteristic is shown using superposition of various degree of space coiled structures. Through this study we investigate the effectiveness of the miniaturized Helmholtz resonators formed using air structures and the echo reduction results show promisses in the application of achieving underwater stealth.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.7
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• pp.753-759
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• 2014

This paper introduces the reduction design technique of the resonance phenomenon of the inner PCB based on power integrity from the analysis about the inner power supply line generating RLC resonance. With the technique, the resonant frequency resulted from the structural characteristics of the PCB can be analyzed and allows to predict and the capacitor for resonance phenomenon reduction can be decided as a decoupling capacitor. From the simulation result, it was confirmed that the PCB's resonance phenomenon reduction design technique should have the reduction effect in the inner motherboard of the industrial controller. This research will be contributed to the improvement of the safety of a PDN (Power Delivery Network) structure in the layout design technique of the PCB.

• Korean Journal of Optics and Photonics
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• v.26 no.6
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• pp.306-311
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• 2015

We report the characteristics of a single-wavelength-tunable fiber laser using a polymer waveguide Bragg grating (PWBG) wavelength filter. The output of the laser depends on environmental conditions, such as temperature and polarization states in the laser cavity. Wavelength tuning can be achieved, about 16.29 nm from 1548.24 nm to 1531.95 nm, according to the electric power applied to the PWBG wavelength filter. The achieved efficiency slope is about -0.16 nm/mW. A side-mode suppression ratio (SMSR) of more than 35 dB can be obtained by adjusting the polarization state in the laser cavity. A stable wavelength-tunable fiber laser can be achieved using the PWBG wavelength filter with a TEC module and a polarization-maintaining fiber.

• Journal of KSNVE
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• v.7 no.1
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• pp.20-29
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• 1997

내부공진은 2자유도계 이상의 다양한 비선형 시스템에 존재할 수 있으며 모드 사이의 진동에너지의 교환의 원인이 된다. 위에서 설명한 흡진기의 경우처럼 그 시스템의 동작에 필수적인 요소가 되기도 하며 직사각형 평판의 경우처럼 선형이론 으로는 예측불가능한 진폭변조된 진동을 유발하기도 한다. 이론적인 해석의 결과 다양한 분기와 여러가지 형태의 해를 가지며, 특히 주기적 정상해와 혼돈적인 해를 갖는 것이 밝혀졌다. 이러한 주기적 정상해는 구조물에 따라 여러 가지 형태로 나타 나며 평판의 경우는 진폭변조된 움직이는 파형으로, 본문에서는 언급하지 않았지만 현의 경우는 타원의 퀘적의 크기와 주축의 방향의 변화로 나타난다. 이러한 다양한 해들은 구조물의 종류와 형상에 따라 다른 형태로 나타나며 향후 연구의 대상이라 생각되어진다.

• Journal of KSNVE
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• v.8 no.6
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• pp.1144-1149
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• 1998

A two degree-of-freedom model of suspended cables is studied for forced resonant response. The method of averaging is used to obtain first-order approximations to the response of the system. A bifurcation analysis of the averaged system is performed in the case of 2-to-1 internal resonance. Nonlinear coupled-mode motions are found to bifurcate from single-mode responses and further bifurcate to limit cycle motions via Hopf bifurcations. The limit cycle solutions undergo period doubling bifurcations to chaos.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.479-480
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• 2011

본 논문은 150W HID 램프용 안정기의 공진 점등에 관한 것으로, 기존의 외부 펄스에 의한 점등 시 램프와 안정기의 거리에 따른 점등전압의 감쇠를 감소시키고자 내부 LC를 이용한 공진 점화부로 하여 기능을 향상하였으나, 벅 컨버터의 인덕터와 커패시터로 공진 기동하여 고전압 점등 파형을 만드는 과정 중 스위치 전류가 커지는 문제가 발생하여, 점등을 위한 공진용 커패시터용량을 줄여 공진 Q점을 나눈 별도의 L(T1)과 C(C2, C3)를 공진 탱크로 이용하여 점등하도록 하였으며, 공진 공진주파수로의 주파수 SWEEP 및 재 점등을 하기 위하여 마이크로프로세서를 이용하였다.

• Korean Journal of Optics and Photonics
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• v.12 no.2
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• pp.143-149
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• 2001

We performed the intracavity frequency-doubling of a tunable continuous-wave Ti:sapphire laser using a lithium triborate $(LiB_3O_5, LBO)$ crystal. For an efficient intracavity frequency-doubling, we measured the spectral and the angular bandwidth about the $\theta$-direction of LBO crystal. The measured values at a fundamental wavelength of 800 nm were 1.54 nm.cm and 3.8 mrad.cm, respectively. As a result of an intracavity frequency-doubling, we obtained the second-harmonic generation output power of 5.3 mW at 400 nm with the full width at half maximum(FWHM) of 0.089 nm from the fundamental output power of 185 mW at 800 nm. The frequency-doubled output was tuned from 397 nm to 403 nm.403 nm.