• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.993-997
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• 2004

파장다중분할 방식의 광통신소자는 단일파장 뿐만 아니라 이웃하는 여러 파장대에서도 동작 할 수 있는 유연성을 갖는 소자가 요구된다. 이를 해결하는 하나의 방법이 파장제어(다중채널)광자결정(Photonic crystal)소자이다. 본 연구에서는 결함층으로 광자결정체 배열구조를 가지는 다중주기 일차원광자결정을 이용하므로 투과광 파장제어가 가능한 가변형 다중채널 투과필터를 얻을 수 있는 이론적 모델과 그에 따라 제작된 $Si/SI_)2$의 광자결정체를 제작하고 그 특성을 고찰하였다. 반사밴드 갭내에 생성된 다중투과-dip의 파장 위치는 이론값과 정착하게 일치하였다. 특히, 결함층 수(N)에 따라 광자 에너지갭내에 2N개의 투과-dip 모드를 생성할 수 있으며, 이들은 주파수범위에 대해 대칭 분포됨을 알 수 있다. 여기에 제안하는 다중채널 투과필터는 외부 전원 없이 입사각도를 미세 조절하므로 파장을 tuning할 수 있다.

• The Journal of the Acoustical Society of Korea
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• v.34 no.3
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• pp.219-226
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• 2015

In this paper, derivation of the STL (Sound Transmission Loss) of a square plate installed in an impedance tube is discussed using an analytic method. Coupled motion of the plate vibration and acoustic field is considered. Vibration of the plate and pressure field inside the tube are expressed in terms of the infinite series of modal functions. Under the plane wave assumption, it is shown that consideration of the first few modes yields sufficiently accurate results. When the boundary of the plate is clamped, vibration mode is assumed as a multiplication of the beam modes corresponding to the crosswise directions. The natural frequencies of the clamped plate are calculated using the Rayleigh-Ritz method. It is found that the STL shows a dip at the lowest natural frequency of the plate, and increases as the frequency decreases below the natural frequency. Comparison of the result in this paper with the STL obtained by measurements and FE computations in the reference shows an excellent agreement.

• The Journal of the Acoustical Society of Korea
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• v.35 no.4
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• pp.253-260
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• 2016

In this paper, derivation of the STL (Sound Transmission Loss) of the double plates installed in an impedance tube is discussed using an analytic method, where an air cavity exists between the plates. Vibration of the plates and sound pressure field inside the tube are expressed in terms of infinite series of modal functions. Under the plane wave assumption, it is shown that consideration of the first few modes yields sufficiently accurate results, and locations of peaks and dips are investigated. It is determined that the peak frequencies of the double plates coincide with those of each single plate. When the two plates are identical, the STL of the double plates as well as that of the single plate become zero at the natural frequencies of the single plate. The location and amplitude of the dips are investigated using an approximation solution when the cavity depth is very small.