• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.425-426
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• 2008

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.83-83
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• 2018

최근 의료, 보건, 헬스케어 분야에 대한 관심이 증가함에 따라 질병의 조기 진단 연구가 각광 받고 있다. 특히 표면증강 라만 산란 (Surface Enhancement Raman scattering)은 고분자 검출을 위해 가장 유용한 물리 화학적 기법으로 SERS를 활용한 특정물질 검출 기술 개발에 대한 연구가 많이 이루어지고 있다. 나노구조의 국부적 표면 플라즈몬의 공명조건 (Surface Plasmon Resonance, SPR)으로 유도된 전자기장은 우수한 SERS 신호를 나타낸다. 따라서 표면 플라즈몬 공명 효과는 귀금속 나노입자의 종류, 크기 및 형태, 기판의 형상 및 구조 등에 의해서 달라지게 되므로 이들을 조절하여 보다 민감한 SERS 신호를 얻을 수 있다. 본 연구에서는 고감도 SERS-Active 기판을 제작하기 위해 SERS 기판 표면의 나노구조를 최적화 하였다. SERS 기판 표면을 제어하기 위해 공정파워, 공정압력, 기판의 온도 등의 증착공정 변수에 변화를 주어 표면의 나노구조를 형성하였다. 이를 분석하기 위해 SEM 분석을 통해 피라미드형 실리콘 기판 표면의 Au 나노구조 금속 박막을 확인하였고, XRD를 이용하여 결정성 및 결정크기를 확인하였다. Rhodamine 6G를 이용한 라만 분석을 통해 SERS 신호의 강도를 알 수 있었다. 금속 나노구조의 형태, 온도 제어를 통해 SERS 신호강도가 우수한 나노구조 기판을 제조 할 수 있었다.

• Nuclear Engineering and Technology
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• v.24 no.1
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• pp.63-74
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• 1992

The resonant formation rates of muonic molecular ion dtr in the muon-catalyzed fusion are calculated in various fuel temperatures and densities. The elastic scattering cross sections between t$\mu$ and deuterons are obtained by making use of the partial wave method. The transition property of the excited compound molecule [(dt$\mu$)dee]＊ derived by the impulse approximation in the form of a bound-state form factor. The radiative, Auger, and collisional deexcitations are considered as the deexcitation mechanisms of the excited dt$\mu$, and each deexcitation width is calculated as well as back decay width. The resultant reaction widths are used to calculate the formation cross sections of resonant dt$\mu$. The resonant formation rates for dt$\mu$-d and dt$\mu$-t collisions are computed as functions of fuel temperature and density. The calculations show that the resonant formation rates increase with fuel densities and have the maximum values at the particular temperatures where the relative collision energies are equal to the resonant ones.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1697-1704
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• 1994

Elastic wave propagation in discrete random medium studies to predict dynamic effective properties of composite materials containing spherical inclusions. A self-consistent method is proposed which is analogous to the well-known coherent potential approximation. Three conditions that must be satisfied by two effective elastic moduli and effective density are derived for the time without limit of frequency. The derived self-consistency conditions have the physical meaning that the scattering of coherent wave by the constituents in effective medium is vanished on the average. The frequency-dependent complex effective wave speed and coherent attenuation can be obtained by solving the derived self-consistency conditions numerically. The wave speed and attenuation obtained from present theory are shown to be in the better agreements with previous experimental observations than the previous theory.

• Journal of the Korean Magnetics Society
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• v.24 no.2
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• pp.60-65
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• 2014

We obtained resonance field ($H_{res}$) and linewidth (${\Delta}H_{PP}$) from measured ferromagnetic resonance signal in the functions of polar angle (${\Theta}_H$) in Ni thin film of 240 nm thickness fabricated by electrodeposition method. The angular dependence of $H_{res}$ was well fitted with the calculated ones. We confirmed that the g-factor and effective demagnetization field were 2.18 and 445 emu/cc by the theoretical analysis of the resonance field, respectively. The angular dependence of ${\Delta}H_{PP}$ showed very large values at in-plane direction (${\Theta}_H=90^{\circ}$), which could not explained by the homogenous linewidth due to the Gilbert damping and inhomogeneous linewidth due to the angular variations and magnetization variations by the surface layer. Therefore, we considered the spin wave scattering (two magnon scattering) process in order to analyze the measured inhomogeneous linewidth, which was appeared in thicker film than the critical thickness of 50 nm. The defect medicated spin wave scattering played a key role in the electrodoposited Ni thin film of 240 nm thickness.

• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.335-340
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• 2011

The solution properties of sodium n-dodecyl sulfate, as an anionic surfactant in the presence of a cationic watersoluble 5, 10, 15, 20-tetrakis (N-methylpyridinium-4-yl) porphyrin (TMPyP) has been comprehensively studied by means of conductometry, UV-vis and resonance light scattering (RLS) spectroscopies. The results represent the decreasing of critical micelle concentration of SDS solution due to increasing of TMPyP concentration. The stabilization of SDS micelle is due to neutralization of negative charge at the micelle surface. The presence of three different species of TMPyP in SDS solution has been unequivocally demonstrated: free porphyrin monomers, porphyrin monomers or aggregates bound to the micelles, and nonmicellar porphyrin/surfactant aggregates. Our results show SDS induced an aggregation in TMPyP. In fact two kinds of J-aggregations were observed: one of them for porphyrin monomers or aggregates bound to the micelles and the other for nonmicellar porphyrin/surfactant aggregates. However, the results represent the electrostatic interaction of TMPyP with SDS anion below the cmc.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.504-509
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• 1998

A new method is proposed for the isolation of resonances from scattered waves for acoustic wave resonance scattering problems. The resonance scattering function consisting purely of resonance information is defined. Acoustic wave scattering from a variety of submerged bodies is numerically analyzed. The classical resonance scattering theory (RST) and the new method compute identical magnitude of the resonance from each scattered partial wave, however, the phases are significantly different. The exact .pi.-radians phase shifts through the resonance and anti-resonance show that the proposed method properly extracts the vibrational resonance information of the scatterer. Due to the difference in the phase of each, partial wave, the new method and RST generate different total resonance spectra.

• The Journal of the Acoustical Society of Korea
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• v.17 no.6
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• pp.54-61
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• 1998

중주파수대역은 내부 음향 모드의 공명 및 모드간 상호 간섭 특성을 완전히 무시할 수는 없으나 모드 밀도가 비교적 높기 때문에, 기존의 저주파수용 모드기법이나 고주파수에 대한 통계적 및 기하학적 해석방법과는 다른 기법이 필요한 구간이다. 본 논문에서는 위상 을 포함한 기하음향모델을 이용하여 중주파수 특성을 고려하는 개념을 이용하여 해석기법을 확립하였으며, 삼각형빔법을 기초로 한 모델링을 하였다. 세 개의 서로 다른 특성을 지닌 대 상 공간에 대해 음향 경계요소법 및 실험에 의한 음향 주파수응답함수와 본 연구 결과를 비 교함으로써 유효성과 오차특성을 검토하였다. 이로부터 위상으로 고려한 중주파수 대역에 잘 적용될 수 있음을 확인하였고, Schroeder의 차단주파수 이하의 저주파수에서는 내부구조 에 의한 회절이, 차단주파수의 네 배 이상인 고주파수에서는 벽면에서의 산란이 간섭현상과 함께 고려되어야 함을 보였다. 이러한 해석기법은 중주파수대역에 있어서 청감특성을 고려 한 내부공간의 음향설계에 매우 유용할 것으로 사료된다.

• Korean Journal of Optics and Photonics
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• v.28 no.3
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• pp.97-102
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• 2017

In this paper, we investigate the optical properties of $Ag@Fe_3O_4$ nanoparticles (NPs) composed of a plasmonic core and a magnetic shell. As the $Fe_3O_4$ shell with high refractive index (~2.42) is formed on the surface of the silver NPs having diameter of 60 nm, the wavelength of the localized surface-plasmon resonance (LSPR) is shifted from 420 nm to 650 nm, a so-called "redshift". Furthermore, through the use of three simulation models ($Ag@Fe_3O_4$ NP, $Fe_3O_4$ shell NP, and silver NP), the peak at 410 nm is seen to be the result of scattering by the $Fe_3O_4$ shell with 60 nm thickness, which would be useful in comprehending the complex optics in various nanoscale assemblies using similar NPs.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.3
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• pp.209-214
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• 2017

A plane-wave incident upon asymmetric multi-layered dielectric grating as well as symmetric grating structure generates space harmonics. Selected space harmonics among those harmonics can undergo strong resonance scattering variations known as GMR(guided-mode resonance). In this paper, to clarify these effects, the field propagation and dispersion curve inside the grating region are analyzed by using a rigorous equivalent transmission-line theory(RETT) based on eigenvalue problem. The results show that, at the peak of a scattering resonance, the reflected mode is almost identical to a leaky wave that can be supported by the grating structure. Thus, it confirms to be occurred GMR effect associated with the free-resonant character of leaky waves at asymmetric multi-layered dielectric gratings. Quantitative simulation results illustrating the behavior of typical gratings are given, and the special case of normal incidence is discussed for TE and TM modes.