• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.4
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• pp.8-12
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• 2003

Characteristics of optical transceiver module in radio frequency(RF) band were investigated with TO-can packaged Fabry-Perot laser diode(FP-LD). R-L-C parameters for equivalent circuit model of the LD were extracted with an impedance analyzer. With this model, impedance matching to the packaged LD could be performed by eliminating inductive components of the leads in the package by using lumped chip capacitors that have opposite reactance, while it shows resonance dip in low frequency band. The resonance dip could be removed using lumped elements for impedance matching by shifting the resonance frequency to the region out of interest.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1615-1616
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• 2006

본 논문에서는 표면 플라즈몬 공명(Surface Plasmon Resonance) 센서의 여러 파라미터를 동시에 만족시키는 설계기법을 제시하였다. 설계 파라미터는 반사광 dip의 3dB bandwidth와 dip의 깊이이고 목적함수는 해석치와 목표치의 차이 벡터의 norm으로 정의하였다. 설계 변수는 박막된 각 금속 충의 두께로 하였고 SPR 센서의 스펙트럼을 해석하기 위해 광학 어드미턴스 기법을 이용하였다. 최적화 기법은 (1+1) 진화 알고리즘을 사용하였다. 설계방법을 3층 구조의 SPR 센서에 적용하여 최적 설계한 파라미터는 초기값에 비해 3dB bandwidth는 4.8nm, dip의 깊이는 1.1dB 향상되었다.

• Journal of Sensor Science and Technology
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• v.14 no.6
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• pp.402-408
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• 2005

This paper describes the optimal design of a multi-layered surface plasmon resonance sensors to meet various specifications and improve some physical parameters. Dip 3 dB bandwidth and depth were chosen as design parameters and the objective function was the norm of the difference between design parameters and target values. The design variables are thicknesses of each layer and to obtain the design parameters, the optical admittance method was employed. The (1+1) evolution strategy was employed as an optimization tool. By applying the proposed optimization procedure to a 3-layered sensor, the optimized design variables considerably improved the 3 dB bandwidth by 4.8 nm and the dip depth by 1.1 dB.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.9
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• pp.834-840
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• 2010

The Sound reduction indices(SRIs) of interior door with 13 different size apertures are measured in acoustic chamber. Also, as a theoretical approach, the SRIs are estimated using Gomperts' theory. In this study, the aperture of interior door is focused on the lower part of door leaf which is well known as a main cause to deteriorate the sound insulation performance of door. The results show that the SRI of door strongly depends on the aperture width and the dip in the measured sound reduction index curve by the resonance effect within aperture is observed at high-frequency. On the whole, the values calculated by theory are in good agreement with the measured values including the position of resonance dip. The average difference between the measured and the calculated values is 0.9 dB for 13 doors with different size aperture in terms of the weighted SRI.

• Journal of the Korean Physical Society
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• v.73 no.9
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• pp.1399-1404
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• 2018

This study used an inductively coupled plasma (ICP) dry etching process with a metal amplitude mask to fabricate a double-side notched long-period fiber grating (DNLPFG) for loading sensing. The DNLPFG exhibited increasing resonance attenuation loss for a particular wavelength when subjected to loading. When the DNLPFG was subjected to force loading, the transmission spectra were changed, showing a with wavelength shift and resonance attenuation loss. The experimental results showed that the resonant dip of the DNLPFG increased with increasing loading. The maximum resonant dip of the $40-{\mu}m$ DNLPFG sensor was -26.522 dB under 0.049-N loading, and the largest force sensitivity was -436.664 dB/N. The results demonstrate that the proposed DNLPFG has potential for force sensing applications.

• Journal of IKEEE
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• v.11 no.2
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• pp.77-82
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• 2007

This paper decribess the strain and temperature sensor using fiber optic surface plasmon resonance sensor. The sensor head is 3-layered, Cr, Ag, Au and we showed feasibility to use this sensor to measure strain and temperature.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.9
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• pp.634-640
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• 1999

Resonance radiation trapping has a great influence on the characteristics of vacuum ultraviolet(VUV) photon emissions in AC PDP cell. We calculate the spatial andspectral distributions of VUV photons, which are radiated by excited Xe in AC PDP cell by Monte Carlo method. Especially a dip in the spectrum at center frequency is discovered both in simulation and in experiment. We give a physical explanation of this phenomenon by the concept of frequency-dependent mean free path of VUV photons.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.475-480
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• 2003

Nanocomposite of Au doped ZrO$_2$ films was prepared, which could be used as non-linear optic materials, selective absorption and transmission films. After heat treatment of prepared thin film by dip-coating method, the characteristics were investigated by X-ray diffraction, UV-VIS Spectrometer, Atomic Force Microscopy (AFM) and Scanning Electron Microscope (SEM). Film thickness was about 150 nm, the Au particle size was 15~35 nm. The thin film had a smooth surface roughness about 1.06 nm. Nonlinearity optics was found that films showed absorption peak at 600~650 nm visible region by plasma resonance of Au metal particles.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.305-305
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• 2011

표면 플라즈몬 공진(SPR) 현상을 이용한 광섬유 센서는 SPR 센서의 우수한 표면 민감도, 비표지 검출능 등의 특징은 유지하면서 측정시스템이 단순해지고 저렴하게 제작이 가능하며 원거리 검출에 유리하다는 장점으로 많은 연구가 진행되고 있다. 최근 스택 제어가 용이하고 민감도 또한 우수하다는 이유로 측면 연마형 센서 구조를 적용한 연구가 많이 이루어지고 있다. 본 연구에서는 기존 Kretchman형태의 SPR 센서의 분해능 향상을 위해 사용된 광도파로 구조를 측면 연마형 광파이버에 적용시켰다. 금속 층 / 유전체 층 / 금속 층으로 구성되어 있는 광도파로 구조와 Au 단일 층을 사용한 기존 구조에 대한 이론 전사모사를 진행하고 실물 소자를 제작하여 특성을 평가하였다. WCSPR 센서에서는 두 개의 반사율 dips이 나타난다. 하나는 단파장영역에서 나타나는 폭이 작은 형태이며 또 다른 하나는 장파장영역에서 나타나는 폭이 넓은 형태이다. 단파장에서의 dip은 입사각에 크게 영향을 받지 않기 때문에 Wavelength interrogation mode을 이용하는 광섬유 SPR센서에 적용할 경우 분해능이 향상될 것 이다. WCSPR 센서는 도파로의 유전체층에서 진행되는 모드를 이용하면 Self-referencing을 할 수 있다, 또한 유전체 층의 두께를 변화 시켜 중심파장의 위치를 조절할 수 있는 특징을 갖고 있다. 결과적으로 광도파로 구조를 광파이버에 적용시켜 기존 Au 단일 층 구조의 SPR 센서에 비해 좀 더 정확하고 광범위한 감지를 할 수 있다.

• Korean Journal of Radiology
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• v.21 no.4
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• pp.462-470
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• 2020

Objective: To demonstrate that human visual illusion can contribute to sub-endocardial dark rim artifact in contrast-enhanced myocardial perfusion magnetic resonance images. Materials and Methods: Numerical phantoms were generated to simulate the first-passage of contrast agent in the heart, and rendered in conventional gray scale as well as in color scale with reduced luminance variation. Cardiac perfusion images were acquired from two healthy volunteers, and were displayed by the same gray and color scales used in the numerical study. Before and after k-space windowing, the left ventricle (LV)-myocardium boarders were analyzed visually and quantitatively through intensity profiles perpendicular the boarders. Results: k-space windowing yielded monotonically decreasing signal intensity near the LV-myocardium boarder in the phantom images, as confirmed by negative finite difference values near the board ranging -1.07 to -0.14. However, the dark band still appears, which is perceived by visual illusion. Dark rim is perceived in the in-vivo images after k-space windowing that removed the quantitative signal dip, suggesting that the perceived dark rim is a visual illusion. The perceived dark rim is stronger at peak LV enhancement than the peak myocardial enhancement, due to the larger intensity difference between LV and myocardium. In both numerical phantom and in-vivo images, the illusory dark band is not visible in the color map due to reduced luminance variation. Conclusion: Visual illusion is another potential cause of dark rim artifact in contrast-enhanced myocardial perfusion MRI as demonstrated by illusory rim perceived in the absence of quantitative intensity undershoot.