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상분리법을 통하여 제조된 새로운 개념의 지지형 액막의 기체투과특성
최평호,김범식,이정민,김철웅,구기갑,이상학 한국공업화학회 2004 공업화학 Vol.15 No.1
새로운 지지형 액막(SLM)을 용매 증발에 따른 1차, 2차 상분리법으로 3성분 고분자 용액으로부터 제조하였다. 액막재로 이온액인 BMIBF_(4) (BMI+ =1-(1-butyl)-3-methylimidazolium, BF_(4)=tetra-fluoro boratr)와 매트릭스 고분자로 polyvinylidenefluoride(PVDF)가 사용되었다. 이 고정화 액막의 O_(2), N_(2) 그리고 CO_(2) 기체 투과특성을 여러 조작 조건에서 조사하였다. SLM은 가혹한 조건에서 조작하였음에도 불구하고 오랜 시간동안 높은 CO_(2) 투과도 및 선택성을 유지하였다. 투과거동을 나타내는 인자인 투과도, 확산도, 그리고 용해도를 연속 측정 장치를 통하여 구함으로써 특성을 관찰하였다. SLM은 다른 기체에 비하여 CO_(2)에 대해서 높은 투과도와 선택도를 갖고 있었다. 특히, 막내 CO_(2)의 용해도는 다른 기체들에 비하여 매우 높은 반면 확산도는 큰 차이를 보이지 않았다. 또한 막내 이온액의 조성은 CO_(2) 용해도에 영향을 관찰할 수 있었다. 막내 이온액의 조성이 증가함에 따라서 CO_(2) 의 투과도 및 선택도가 극격히 증가하였다. 이는 SLM를 통한 기체 투과에 있어서 용해도가 주인자로 큰 영향을 끼침으로써 막내 이온액 조성 증가 SLM의 투과에 큰 영향을 미침을 확인하였다. The new supported liquid membranes (SLMs) were fabricated from ternary polymer solution contained ionic liquid in which primary and secondary phase separations were induced by the solvent by the solvent evaporaton. The used ionic liquid and polymer matrix were BMBF_(4) (BMI+=-(1-butyl)-3-methylimidazolium, BF_(4)-tetra-fluoro boratel and polyvinylidene fluoride (PVDF). Gas permeation properties of the SLM to O_(2), N_(2) and CO_(2) were studied at various operating conditions. Although the SLM were operated under severe operating condition, it maintained high CO_(2) permeability and selectivity for quite long time. The solubility coefficient of CO_(2) in the membrace was very high in comparison with those of other gases; whereas there was no big difference in the diffusivity between CO and other gases. Moreover, in the permeation of pure gases, it is observed that the ionic liquid content in the membrane affected the solubility of CO_(2) in the memhranc. With increasing ionic liquid content in the membrane, the permeability and selectivity of CO_(2) increase significantly. There fore, in the permeation of gases through SLM, the overall permeation performances weir affected mainly by solubility coefficient. This observation can be discussed in terms of the influence of solubility coefficient with ionic liquid content in the membrane.
Characteristics of Sŏlc Filters in X<sup>(2)</sup> Nonlinear Photonic Crystal
Kee, Chul-Sik,Lee, Jong-Min,Lee, Yeung-Lak Optical Society of Korea 2007 Current Optics and Photonics Vol.11 No.3
The characteristics of $S\breve{o}lc$ filters in $X^{(2)}$ nonlinear photonic crystals, periodically poled lithium niobate ($LiNbO_3$), were investigated by the Jones matrix method. The transmittance increases and the full width half maximum of the filter becomes narrow as the duty ratio increases. However, the filtering wavelength does not change. The transmittance at the filtering wavelength is over 95% when the duty ratio is larger than 0.35.
Photonic band gaps of two-dimensional ZnO nanorod photonic crystals
Kee, Chul-Sik,Ko, Do-Kyeong,Lee, Jongmin Institute of Physics [etc.] 2005 Journal of physics. D, applied physics Vol.38 No.21
<P>We have calculated the photonic band structures of two-dimensional periodic arrays of well aligned ZnO nanorods with a frequency dependent dielectric constant. The ZnO nanorod photonic crystal can exhibit a photonic band gap in the visible range. The dependence of the band gap on the period and radii of the nanorods was shown. From the finite difference time domain simulations, we also showed that the luminescence of a ZnO nanorod could be altered by the photonic band gap effect. Controlling the luminescence of ZnO nanorods can be useful in the implementation of efficient light emitting devices.</P>
Optimal Transparent One-Dimensional Metallo-Dielectric Photonic Crystal Structures
Chul-SiK Kee,Hanjo Lim,Kihong Kim 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.47 No.1
We theoretically investigated the optical transmission of ¯nite one-dimensional metallo-dielectric photonic crystals composed of Ag and ZnS layers. The transmission spectra strongly depend on the positions of the metal layers in the unit cell. The intensity and the bandwidth of the transmission increase when the Ag layer is closer to the center of the unit cell. The phenomena are due to the anti- re°ection coating eect caused by the outer dielectric layers. Optimal transparent metallo-dielectric photonic crystal structures can be useful in improving the performance of thin-¯lm devices, such as transparent heat mirrors and transparent electrodes.
Chul-SIk Kee 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.I
We study the effects of a negative index of left-handed material on the resonant transmission through Fabry-Perot (FP) resonators. Due to the negative optical length of a left-handed material layer, the resonant frequency of the metallic FP resonator with a left-handed material layer of $-\epsilon$, $-\mu$, and thickness $d$ is higher than that of the resonator with a right-handed material layer of $\epsilon$, $\mu$, and thickness $d$. The resonant transmission through a metallic FP resonator with a pair of the right- and left-handed material layers can be forbidden when the right- and the left-handed material layers are optically annihilated. We also discuss the effects of the negative index of a left-handed material on resonant transmission through a dielectric FP resonator.
Photonic crystal multi-channel drop filters based on microstrip lines
Kee, Chul-Sik,Park, Ikmo,Lim, Hanjo Institute of Physics [etc.] 2006 Journal of Physics. D, Applied Physics Vol.39 No.14
<P>We propose photonic crystal (PC) multi-channel drop filters implemented using microstrip lines. Their performance is based on coupling between the cavity modes of microstrip PC cavities and the guiding modes of microstrip waveguides. The dropping frequency can be controlled by correct design of the cavity. The proposed multi-channel drop filter can be useful for implementing new types of functional microwave filters.</P>
기철식(Chul-Sik Kee),최춘기(Choon-Gi Choi),윤근병(Keun Byoung Yoon),한상필(Sang-Pi Han),정명영(Myung Yung Jeong) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
We present that two-dimensional periodic nano-patterns can be embossed on a polymer thin film using the nano-imprint process. The silicon masters with triangular arrays of rods such as square, hexagon, dodecagon and circle were successfully fabricated using the e-beam lithography and inductively coupled plasma etching. We also show that the polymer thin films with two-dimensional periodic patterns, polymer photonic crystals, can exhibit electromagnetic stop bands and the line defects introduced in the periodic patterns can serve as low loss waveguides from the photonic band calculations and the finite difference time domain simulations.
Spectral Properties of THz-Periodic Metallic Structures
Chul Kang,Chul-Sik Kee,Ik-Bu Sohn Sohn,Jongmin Lee 한국광학회 2008 Current Optics and Photonics Vol.12 No.3
We have investigated spectral properties of the periodic arrays of aluminum rods and holes on papers using the terahertz time-domain spectroscopy. The size of a rod (hole) is 600 μm × 100 μm and the spacing is 300 μm. The samples were fabricated by a femtosecond laser micromachining system. The periodic arrays of aluminum rods exhibit high reflection around 0.25 THz when the polarization of the THz pulse is parallel to the long axis of the rod, whereas the periodic arrays of holes exhibit high transmission around 0.25 THz when the polarization of the THz pulse is perpendicular to the long axis of the hole.