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Modern helicopter rotor blades with non-homogeneous cross section which are made from anisotropic material require highly sophisticated structural analysis. Variation in cross section geometry make this task of analysis more complicated. The dynamic and static behavior of rotor blades is mainly influenced by the cross sectional properties, which depend upon the coordinates of the shear center and elastic center as well as bending and shear stiffness. The material can be homogeneous or non-homogeneous, isotopic or anisotropic. By comparing the results of this numerical approximation for cross sections with known exact solutions, it can be seen that a simple method to determine the cross sectional properties of composite helicopter blades is presented based on the elementary beam theory.
The synthetic process and characteristics of organic /inorganic composite 2nd-order NLO materials with modified polyimides was studied in this study with accumulated experiences in the developments of organic/inorganic hybrides NLO materials via Sol-Gel process and in the fabrication of PI. In a detail contents, alkoxy silane dye was made using disperse red1(DR1) with high optical nonlinearity and PI with good thermal stability. The alkoxy silane DR1 will be treated into film form through Sol-Gel process with silane coupling agent. The film form of alkoxy silane DR1-PAA was heat-treatmented after go through the corona poling technique process. So, the of organic/inorganic composite NLO materials of chemical cross-linking structure as highly electro-optic coefficient which results from the formation of imide combination because of excellent thermal stability of imide combination and Si-O combination and stabilization of dye orientation through heat treatment and corona poling technique process.
열방향성 poly(ester amide) (상품명 Vectra)와 열가소성 polycarbonate(상품명 Lexan)로부터 장섬유 복합재료를 제조하였다. 액정고분자인 Vectra는 낮은 용융점도로 인해 가공조제인 동시 복합재료의 분산상으로 사용되었으며, 장섬유를 형성할 경우 높은 탄성률로 인해 보강재의 역할을 할 수 있을 것으로 기대되었다. Vectra가 장섬유를 형성할 수 있는 재료 및 압출성형의 인자들을 체계적으로 조사하였으며, 그 결과로부터 섬유상의 형성과정을 유추, 제안하였다.
In this study the lysis reaction of lysozyme to Micrococcus lysodeikticus cell(ML cell) was investigated to develop the quick and accurate assay technique for lysozyme concentration. For the investigation of the lysis reaction of lysozyme the Michaelis-Menton(M-M) reaction mechanism was applied and Lineweaver-Burk plot was used to calculate the reaction rates. The concentration of lysozyme and ML cell were changed from 2.0 to 10.0mg/l and from 10 to 50mg%, respectively. In these range of concentrations of the lysozyme and ML cell the lysis reaction was good agreement with M-M reaction mechanism and then the maximum reaction constant and Michaelis-Menton constant were measured as 1.40×10^(-2) and 11.08, respectively. These information on the lysis reaction contributes to the better analysis of lysozyme concentration in comparison with conventional procedure.
The purpose of this investigation was to prepare far-infrared radiant by ceramics made from using a domestic basalt as starting material mixed with a high alumina cement as ceramic binder. The characteristics of far-infrared radiation on the several kinds of the mixed materials, without heatreted and the treated compounds, were studied. These results revealed that the basalt mixed with CaO-Al₂O₃ cement increase in the emissive intensity were detected in the sample dried at 110℃ than the samples sintered at 1,100℃. And the radiants consists of the basalt with CaO-Al₂O₃ cement increased in wavenumbers 1000-1200cm^(-1). The effect of the emissive intensity suggest that the sample shifted to lower wavenumber with the increase in content of alumina contained in the compound.
포장 재료의 특성시험으로 가장 합리적인 시험법인 회복탄성계수 (Mg) 시험에 의한 아스팔트 포장 재료의 특성을 조사하였다. 이 회복탄성계수 시험법은 하중을 반복적으로 재하제재하하므로써 실제 도로가 받는 하중상태를 재현한 시험법이다. 입상재료에 대해서는 반복재하 삼축압축시험을 AASHTO T274 시험법에 따라 실시하였고, 아스팔트 재료에 대해서는 ASTM D4123 시험법에 따라 반복재하 간접인장 시험을 통하여 실시하였다. 실내시험 결과 입상재료의 비선형 회복탄성거동이 관찰되었으며, 체적응력과 축차응력이 회복탄성계수의 변화에 가장 주요한 변수임을 알 수 있다. 아스팔트 재료에 대하여는 회복탄성계수는 온도의 변화에 매우 민감하여 log M_(R) 이 온도에 선형 반비례함을 알 수 있다. 또한 본 연구에서 제안된 구성모델에 의해 예측된 회복탄성계수값이 실내시험 결과와 잘 일치함을 알 수 있다.
In helicopter blade design, it is essential to get the accurate dynamic characteristics of the composite helicopter rotor blades including natural frequencies and mode shapes, which determine the susceptibility of the rotor system to aeroelastic instability and large vibratory response. In this study, the dynamic characteristics of helicopter rotor blades are investigated with various composite material twisted cross sections, ply angles, and rotation speed.
The purpose of this study is to develop the radiators using construction materials in the long wavelenghs such as the far IR at low temperatures. In order to extend to emissivity range of the far IR of the materials and also improve the radiation properties of ceramic substances. The radiants for far IR radiation which are on use in the domestic buildings are investig-ated, and these characteristic values are compared with each other. The conditions for the proper mixed ratio of inorganic cements and ceramic materials of silicate system were added as the binding agents such as portland cements and alumina gel. The results obtained are summarized as follows; Emission properties of the sintered clay specimen by penetrating of carbon black and transitional metals at 900℃ for 2 hours was obtained higher than using cements, basalt and silicon carbide main materials and addition of powdered glass, CuO and MnO_(2) ingredients as active materials.
First, four different substrates, Si, SiO_(2), WN, and TiN, were used to examine the Cu deposition mechanism at the substrate surface. The initial stages of nucleation, density and grain size of the Cu thin film were investigated by performing the deposition at substrate temperatures ranging from 150 to 220℃ with a deposition time of 1 min. The results showed an increase in the Cu nuclei size with increasing deposition temperature for all four substrates. More specifically, WN and TiN substrates showed particle sizes at low temperature (150℃) which were significantly larger than for Si and SiO_(2) substrates nuclei sizes. Selective Cu deposition was achieved by depositing a TiN layer on a SiO_(2) substrate followed by patterning, thus creating two separate SiO_(2) and TiN surfaces. In order to study selective factors of Cu thin films, after SC1 cleaning, HF treatment and passivation treatment of the substrate, we have investigated deposition properties of selective Cu thin films. According to the pretreatment methods of the substrate surface, it showed very sensitive selective deposition properties from the experiment's result. Thus, from the above result, though Cu dry echting technique at room temperature is not yet developed, we could get some possibility to use Cu as semiconductor metallization.
Modern helicopter rotor blades with non-homogeneous cross section which are made from non-isotropic material require highly sophisticated structural analysis. Variation in cross section geometry make this task of analysis more complicated. The dynamic and static behavior of rotor blades is mainly influenced by the cross sectional properties, which depend upon the coordinates of the shear center and elastic center as well as the bending and shear rigidity. In this study, a simple method to determine the cross sectional properties of composite helicopter blades is presented based on the elementary beam theory.