• 한국농공학회지
• /
• 제35권1호
• /
• pp.59-66
• /
• 1993

Ring Sector Plate Supported by Elastic Beam Although all the reinforced concrete circular ring sector plates are elastically supported, it is conventional to simplify their supporting conditions as fixed or simply-supported ones assuming that their supporting beam has infinite stiffness. However, in order to obtain a precise solution, it should be required to consider the stiffness of their supporting beam. As a methodological improvement to the precise analysis, "Reinforced Concrete Model" previously developed by the author was applied to the structural analysis of the reinforced concrete circular ring sector plates with elastically supported beam. The results of analysis in the cases under various conditions of open angle, steel ratio, relative stiffness(EI/DL) between plate and supporting beam were summarized as follows ; 1.Although the effect of relative stiffness between plate and supporting beam varies depending on the magnitude of open angle, in general, it shows the largest when not more than 5.0 and negligible when not less than 10.0. Therefore, it would be considered as fixed supporting condition :in the case of its open angle of 0$^{\circ}$rectangular plates), its stiffness ratio being not less than 10.0 and in the other case of its open angle of 30$^{\circ}$, its stiffness ratio being not less than 5.0. 2.In the rectangular plates, the effect of steel ratio is considerable in no supporting condition, but neglible in the supporting condition. So, the effect of steel ratio should be negligible in the case of the elastically supported circular ring sector plates. 3.However, the effect of steel ratio is much more considerable in the case of the fixed supported circular plates, especially, when steel ratio being not more than 1.0% and stiffness ratio being smaller. So, the effect of steel ratio should be considered in the analysis of reinforced concreate circular ring sector plates with fixed conditions. 4.The effect of open angle is greater in the case of without-supporting beam conditions. However, in the other case of with-supporting beam conditions, the effect is a little bit when open angle of not more than 300 and negligible when open angle of not more than 30$^{\circ}$.

• 한국광학회지
• /
• 제12권6호
• /
• pp.446-451
• /
• 2001

레이저 유도 격자 분광장치를 제작하여, $C_3$ $H_{8}$ 층류 확산화염에서 생성된 열 격자 신호를 측정하였다. 열 격자를 생성시키기 위한 여기광은 파장이 532nm인 Nd:YAG 레이저를 사용하였고, 검침광은 488nm의 CW A $r^{+}$레이저를 이용하였다. 검침 광의 세기를 변화시켜 장치의 회절효율과 신호 특성을 측정하였다. 측정된 열 격자 신호의 세기를 분석하여 화염내의 매연의 농도 분포를 정성적으로 측정하였고, 신호의 주파수 변화를 측정하여 온도 분포를 구하였다.

• 한국정밀공학회지
• /
• 제14권5호
• /
• pp.34-41
• /
• 1997

The dimension measurement problem of products has been a major concern in the quality control in the industrial fields. A non-contacting measurement system using the vision sensor is proposed in this paper. The system consists of a CCD camera for the image capture, a frame grabber for the acquired image processing, a laser unit for the illumination, scanning unit for the measurement, and a personal computer for the geometry computation. The slit beam which is generated by passing the laser beam through a cylin- drical lens is fired to the axial-symmetric object on the rotating plate. The image of objects reflected by the laser slit beam, acquired by the CCD camera, becomes much brighter than the other parts of objects. After the histogram of brightness for the captured image is calculated, low intensity pixels are filtered out by threshold method. The performance of proposed measurement system is obtained for several different axial symmetric objects. The proposed system is verified as a good tool for measuring axial-symmetric parts in a limited condition with a minor investment cost.

• Structural Engineering and Mechanics
• /
• 제26권5호
• /
• pp.569-589
• /
• 2007

This paper presents an analytical model for RC beam-column connections that takes into account bond deterioration between reinforcing steel and concrete. The model is based on the Lumped Damage Mechanics (LDM) theory which allows for the characterization of cracking, degradation and yielding, and is extended in this paper by the inclusion of the slip effect as observed in those connections. Slip is assumed to be lumped at inelastic hinges. Thus, the concept of "slip hinge", based on the Coulomb friction plasticity theory, is formulated. The influence of cracking on the slip behavior is taken into account by using two concepts of LDM: the effective moment on an inelastic hinge and the strain equivalence hypothesis. The model is particularly suitable for wide beam-column connections for which bond deterioration dominates the hysteretic response. The model was evaluated by the numerical simulation of five tests reported in the literature. It is found that the model reproduces closely the observed behavior.

• Progress in Superconductivity
• /
• 제8권2호
• /
• pp.175-180
• /
• 2007

High temperature superconductor $YBa_2Cu_3O_{7-x}$ (YBCO) films have been grown by in-situ electron beam evaporation on artificial metal tapes such as ion-beam assisted deposition (IBAD) and rolling assisted biaxially textured substrates (RABiTS). Deposition rate of the YBCO films is $10{\sim}100{\AA}/sec$. X-ray diffraction shows that the films are grown epitaxially but have inter-diffusion phases, like as $BaZrO_3\;or\;BaCeO_3$, at their interfaces between YBCO and yttrium-stabilized zirconia (YSZ) or $CeO_2$, respectively. Secondary ion mass spectroscopy depth profile of the films confirms diffused region between YBCO and the buffer layers, indicating that the growth temperature ($850{\sim}900^{\circ}C$) is high enough to cause diffusion of Zr and Ba. The films on both the substrates show four-fold symmetry of in-plane alignment but their width in the -scan is around $12{\sim}15^{\circ}$. Transmission electron microscopy shows an interesting interface layer of epitaxial CuO between YBCO and YSZ, of which growth origin may be related to liquid flukes of Ba-Cu-O. Resistivity vs temperature curves of the films on both substrates were measured. Resistivity at room temperature is between 300 and 500 cm, the extrapolated value of resistivity at 0 K is nearly zero, and superconducting transition temperature is $85{\sim}90K$. However, critical current density of the films is very low, ${\sim}10^3A/cm^2$. Cracking of the grains and high-growth-temperature induced reaction between YBCO and buffer layers are possible reasons for this low critical current density.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
• /
• pp.481-486
• /
• 1998

In this paper, elastic and inelastic behavior of exterior joint of moment-resisting R.C frame with non-seismic detail subjected to reversed cyclic lateral load such as earthquake excitations was investigated. 1/2-scals subassemblage exterior beam-column joint including slab was manufactured based on similitude law. Then, pseudo static test under the displacement control was performed. The results of 1)crack pattern and failure mode, 2)degradation stiffness and strength, energy dissipation capacity from load-displacement hysteresis curve, 3)strain of steel were analysed.

• 한국해양공학회지
• /
• 제13권3B호
• /
• pp.56-64
• /
• 1999

An experimental study was carried out to examine the structural behavior of reinforced concrete deep beams strengthened with aramid fiber sheets, carbon fiber sheets and plates, and to propose the reasonable strengthening method for the deteriorated R.C. deep beams. Results show that the most significant differences in behavior of reinforced concrete deep beams strengthened with fiber sheet and plate were mainly due to various fiber orientations and anchorage. Deep beams diagonally strengthened with carbon fibers show better performance compared with those of vertically, horizontally strengthened specimens and produce the increase in the shear resistance through the redistribution of internal forces after the initial cracks occur. However, strengthened deep beams without anchorages might show unreasonable, brittle peeling-off failure of fiber reinforcements.

• 한국구조물진단유지관리공학회 논문집
• /
• 제3권1호
• /
• pp.121-128
• /
• 1999

In this study, the behavior of R/C beams strengthened with carbon fiber laminate (CFL) is analyzed from the test results. CFL is attractive for this application due to its good tensile strength and low weight. Test parameters are the width and the thickness of CFL and repair of damaged specimen. The failure mode and ultimate load are analyzed from these measured data. Test results show that the peak load of specimens strengthened with CFL is increased to 1.27~2.04 times that of non-rehabilitation specimen. The wider lap width, larger amount of CFL, the larger strength is obtained. But the ductile behavior of the rehabilitated specimens is inversely proportional to the CFL thickness.

• Applied Science and Convergence Technology
• /
• 제23권6호
• /
• pp.309-316
• /
• 2014

A large particle accelerator requires an ultrahigh vacuum (UHV) system of average pressure under $1{\times}10^{-7}$ Pa for mitigating the impact of beam scattering from the residual gas molecules. The surface inside the beam ducts should be controlled with an extremely low thermal outgassing rate under $1{\times}10^{-9}Pa{\cdot}m^3/(s{\cdot}m^2)$ for the sake of the insufficient pumping speed. To fulfil the requirements, the aluminum alloys were adopted as the materials of the beam ducts for large accelerator that thanks to the good features of higher thermal conductivity, non-radioactivity, non-magnetism, precise machining capability, et al. To put the aluminum into the large accelerator vacuum systems, several key technologies have been developed will be introduced. The concepts contain the precise computer numerical control (CNC) machining process for the large aluminum ducts and parts in pure alcohol and in an oil-free environment, surface cleaning with ozonized water, stringent welding process control manually or automatically to form a large sector of aluminum ducts, ex-situ baking process to reach UHV and sealed for transportation and installation, UHV pumping with the sputtering ion pumps and the non-evaporable getters (NEG), et al. The developed UHV technologies have been applied to the 3 GeV Taiwan Photon Source (TPS) and revealed good results as the expectation. The problems of leakage encountered during the assembling were most associated with the vacuum baking which result in the consequent trouble shootings and more times of baking. Then the installation of the well-sealed UHV systems is recommended.

• 한국응용과학기술학회지
• /
• 제36권2호
• /
• pp.434-447
• /
• 2019

폴리에틸렌글라이콜(PEG)은 계면활성제, 세정제, 유화제 등으로 화장품에 많이 사용된다. 이들은 제조 과정 중, ethylene oxide의 이량체화에 의해 인간에 몸에 유해한 1,4-dioxane이 부산물로 생성될 수 있다. 화장품 성분에 대한 소비자들의 관심이 증가함에 따라, 퍼스널케어 시장에서 PEG 성분이 없는 보다 안전한 에멀젼 연구의 필요성이 증대되고 있다. PEG-free 계면활성제로 사용되는 polyglycerol ester (PGE)는 비이온성 계면활성제로서 식품, 화장품 등의 분야에서 많이 사용되며 글리세롤과 지방산을 에스테르화 하여 생산된다. 본 연구에서는 PEG 성분을 함유하지 않은 나노에멀젼 제형의 개발 및 안정화를 목표로 하였다. 최적화된 나노에멀젼 제형 개발을 위해 RSM (Response Surface Methodology)를 사용하였다. 독립변수 및 변수의 범위 결정을 위한 예비 실험의 결과로 계면활성제 함량(2~4%), 오일 함량(4~8%), 폴리올 함량(12~24%)을 독립변수로 설정하였다. 반응변수로는 제형의 입자 크기(particle size), 제타 전위(zeta potential), 현탁도(turbidity), 다분산지수(polydispersity index)를 측정하였다. 제조한 나노에멀젼을 FIB (Focused ion beam)로 측정한 결과, 구형의 입자들이 100~200 nm의 크기를 가지고 분포되어 있는 것을 확인하였다. 제조된 제형에 대해 30일 간 각 온도별($4^{\circ}C$, $25^{\circ}C$, $45^{\circ}C$) 안정성 평가를 진행하였고, 최적의 입자 크기, 현탁도, 다분산지수, 제타 전위를 고려한 최적의 처방은 계면활성제(2%), 오일(8%), 폴리올(24%)로 확인되었다.