• 한국세라믹학회지
• /
• 제49권3호
• /
• pp.205-215
• /
• 2012

It has been studied the crystal and block structures of the hexagonal ferrites with M, W, Y and Z types prepared by various coprecipitation-oxidation method. The structures have been refined with a Rietveld analysis of the powder X-ray diffraction pattern with high precision ($R_{WP}$ <0.09, $R_I$ <0.03). The density difference between the S-blocks was proportioned to the cobalt contents in hexagonal ferrites, but that between the R or T-blocks was relatively small. Compared with the blocks and cation-oxygen polyhedra in BaM ($BaFe_{12}O_{19}$), those were bulky to the normal direction for the c-axis in $Co_2W$ ($BaCo_2Fe_{16}O_{27}$) and to the parallel direction for the c-axis in $Co_2Y$ ($Ba_2Co_2Fe_{12}O_{22}$) and $Co_2Z$ ($Ba_3Co_2Fe_{24}O_{41}$). The S-blocks of $Co_2W$, $Co_2Y$, and $Co_2Z$ were unstable and distorted. Because the T-block of $Co_2Z$ was unstable, the T-block was decomposed into the Ba-rich phase and $Co_2W$ at high temperatures above $1200^{\circ}C$. A standard powder X-ray diffraction pattern for $Co_2Z$ was proposed as well.

• Bulletin of the Korean Chemical Society
• /
• 제35권5호
• /
• pp.1317-1322
• /
• 2014

Membrane disruption by an antimicrobial peptide (AMP) was investigated by measuring the $^2H$ solid-state nuclear magnetic resonance spectra of 1-palmitoyl-$d_{31}$-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC_$d_{31}$) in mixtures of POPC_$d_{31}$/cholesterol and either magainin 2 or aurein 3.3 deposited on thin cover-glass plates. The line shapes of the experimental $^2H$ solid-state nuclear magnetic resonance (SSNMR) spectra were best simulated by assuming the coexistence of a mosaic spread of bilayers containing pore structures and a fasttumbling isotropic phase or a hexagonal phase. Within a few days of incubation in a hydration chamber, an isotropic phase and a pore structure were induced by magainin 2, while in case of aurein 3.3 only an isotopic phase was induced in the presence of a bilayer phase. After an incubation period of over 100 days, alignment of the bilayers increased and the amount of the pore structure decreased in case of magainin 2. In contrast with magainin 2, aurein 3.3 induced a hexagonal phase at the peptide-to-lipid ratio of 1/20 and, interestingly, cholesterol was not found in the hexagonal phase induced by aurein 3.3. The experimental results indicate that magainin 2 is more effective in disrupting lipid bilayers containing cholesterol than aurein 3.3.

• 한국의학물리학회:학술대회논문집
• /
• 한국의학물리학회 2002년도 Proceedings
• /
• pp.222-224
• /
• 2002

In proton and heavy ion radiotherapy, compensators are required to modify the energy of heavy ion, to compensate the local difference of tumor depth. Conventional compensators have to be created, exchanged, and stored for each patient and for each irradiation directions. A Cylinder Type Liquid Variable Compensator is and is under development. Hexagonal cylinders will be arranged in honeycomb structure. In which air and fluid are divided by hexagonal pistons. The position of each piston will be changed in each cylinder for adjusting the thickness of fluid for variable compensator. The location of each hexagonal piston is determined by each controlling cylinder connected to the hexagonal cylinder by inlet pipes of fluid. Each controlling cylinder includes controlling a piston, which is moved mechanically. Each controlling cylinder is to be moved by a motor driven by a computer.

• 대한화학회지
• /
• 제38권11호
• /
• pp.785-791
• /
• 1994

$Sr_1-_xY_xMnO_3$ (x = 0.0∼1.0)을 citrate법으로 합성하고 조성에 따른 구조적 전기적 성질의 변화를 알아보았다. X-ray diffraction method에 의해 각 산화물의 구조를 결정한 결과, $Sr_1-_xY_xMnO_3$ (x = 0.0∼1.0) system은 조성에 따라 4L-hexagonal perovskite(x = 0.0∼0.3) 구조, rhombohedral perovskite(x = 0.3∼0.7)구조를 거쳐 hexagonal nonperovskite(x=0.7∼1.0) 구조까지 3가지의 다른 결정구조를 갖는 것으로 관찰되었다. 이러한 $Sr_1-_xY_xMnO_3$ system의 구조 변화는 yttrium 양이 증가함에 따라 cell parameter가 증가하는 경향을 보였으며, 이는 $Mn^{4+}$ 대신 $Mn^{3+}$가 증가함에 따른 것으로 믿어진다. $SrMnO_3$의 $Sr^{2+}$ 자리에 $Y^{3+}$를 치환할수록 conductivity가 크게 증가하는 것이 관찰되었다. 4L-hexagonal구조를 갖는 $Sr_{0.9}Y_{0.1}MnO_3$와 pseudocubic perovskite 구조를 갖는 $Sr_{0.5}Y_{0.5}MnO_3$의 온도에 따른 전기저항 측정결과, $Sr_{0.9}Y_{0.1}MnO_3$에서 더 큰 energy gap을 갖는 것으로 관찰되었으며, 이 결과는 4L-hexagonal구조가 metal-metal 결합에 의해 안정화되어 있기 때문인 것으로 설명된다.

• 한국기계연구소 소보
• /
• 통권16호
• /
• pp.127-136
• /
• 1986

Recently deck crane of multi purpose cargo vessel (MPCV) is designed to posi¬tion in side instead of in the center line of the upper deck with a view to reduce the transportation cost and shipbuilding cost by shortening the length of ship. In this paper, the crane post was at first designed according to the crane maker’s specification and parent ship and the structure is analysed with Finite Ele¬ment Method. Through the careful reviews on the result of analysis, the final design of crane post was modified. The crane post is designed as a cylindrical in upper part and hexagonal in lower part instead of cylindrical on the whole as before. The connecting part of crane post is designed with the form of mixture of the cylinderical and hexagonal. Since the center of cylindrical and hexagonal section are not on the same line, it is expected to have the stress concentration. So, in order to attenuate the concentrated stress on the connecting part, the upper and lower parts was stiffened by inserting plate to enlarge the area of welding. The structure of deck part includes the tank side floor which is depend on the lower structure of the crane post that would support the force of the crane post by placing with 1.5 frame interval of the vertical plate.

• Steel and Composite Structures
• /
• 제45권5호
• /
• pp.683-695
• /
• 2022

Conventional braces are often used to provide stiffness to structures; however due to buckling they cannot be used as seismic energy dissipating elements. In this study, a seismic energy dissipation device is proposed which is comprised of a bracing member and a steel hysteretic damper made of steel hexagonal plates. The hexagonal shaped designated fuse causes formation of plastic hinges under axial deformation of the brace. The main advantages of this damper compared to conventional metallic dampers and buckling-restrained braces are the stable and controlled energy dissipation capability with ease of manufacture. The mechanical behavior of the damper is formulated first and a design procedure is provided. Next, the theoretical formulation and the efficiency of the damper are verified using finite element (FE) analyses. An analytical model of the damper is established and its efficiency is further investigated by applying it to seismic retrofit of a case study structure. The seismic performance of the structure is evaluated before and after retrofit in terms of maximum interstory drift ratio, top story displacement, residual displacement, and energy dissipation of dampers. Overall, the median of maximum interstory drift ratios is reduced from 3.8% to 1.6% and the residual displacement decreased in the x-direction which corresponds to the predominant mode shape of the structure. The analysis results show that the developed damper can provide cost-effective seismic protection of structures.

• E2M - 전기 전자와 첨단 소재
• /
• 제7권1호
• /
• pp.49-56
• /
• 1994

Polycrystalline CdS thin films were deposited by using EBE method and its crystal structure, surface morphology, electrical and optical properties as a function of annealing temperature were investigated. It was found that optimum growth conditions were substrate temperature annealing temperature 300[.deg. C]. The films were hexagonal structure preferred(002) plane and maximum grain size was 421[.angs.]. As the results, resistivity and optical transmittance of CdS thin films were $8.3{\times}{10^3}$[.ohm.cm] and 89[%] respectively.

• Applied Science and Convergence Technology
• /
• 제24권6호
• /
• pp.228-231
• /
• 2015

We investigated the adsorption structures and the initial growth mode of ultra-thin Al films on a W(110) surface at a high temperature. When Al atoms were adsorbed on the W(110) at the substrate temperature of 1100 K and with coverage of 0.5ML, Al atoms formed a p($2{\times}1$) double-domain structure. When the coverage was 1.0 ML, the double domain of a hexagonal structure (fcc(111) face) rotated ${\pm}5^{\circ}$ from the [100] direction of the W(110) surface and another distorted hexagonal structure were found. Low-energy electron diffraction results along with ion scattering spectroscopy results showed that the Al atoms followed the Volmer-Weber growth mode at a high temperature.

• 한국전자파학회논문지
• /
• 제18권2호
• /
• pp.199-205
• /
• 2007

본 논문에서는 초고속 디지털 PCB 회로에서 발생하는 GBN(Ground Bounce Noise)을 억제하기 위한 새로운 EBG(Electromagnetic Bandgap) 구조의 전원면을 제안하였다. 제안된 구조는 육각형 모양의 단위 셀과 각 셀을 연결하는 선로로 구성되어 있다. 육각형 모양의 단위 셀은 등방성을 띄어 인접 셀의 각 포트 사이의 전달 특성을 동일하게 한다. 제안된 구조는 실제 제작, 측정되었고 330 MHz부터 5.6 GHz까지 넓은 주파수 대역에서 -30 dB 이하로 GBN을 억제하는 특성을 나타낸다. Electromagnetic Interference(EMI) 방사 측정 시에도 일반 전원면/접지면에 비해 낮은 EMI 특성을 나타낸다. 본 논문에서 제안한 육각형 EBG 구조의 전원면은 실제 EBG 전원면의 적용에 효율적으로 작용하여 초고속 디지털 회로의 EMI 문제를 해결하는 데 기여할 것으로 기대된다.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
• /
• pp.1568-1571
• /
• 2005

We have evaluated thermal stability of a $BaAl_2Si_2O_8:Eu^{2+}$ $(BAS:Eu^{2+})$, which have polymorph property such as hexagonal, monoclinic structure depending upon firing temperature. When both polymorph $BAS:Eu^{2+}$ were baked in air at 500 $^{\circ}C$ for 30 min, the photoluminescence (PL) intensity of $monoclinic-BAS:Eu^{2+}$ was maintained of the initial intensity. However, the PL intensity of $hexagonal-BAS:Eu^{2+}$ decreased significantly, corresponding to about 34 %. From analyses of Rietveld refinement, the difference of thermal stability of both $BAS:Eu^{2+}$ can be ascribed to both crystal structure of host materials and the average interatomic distances between $Eu^{2+}$ ion and oxygen their crystal structure which plays a key role of shield for Eu2+ ions against oxidation atmosphere.