3,371 research outputs found
Transonic Flutter Suppression of the 2-D Flap Wing with External Store Using CFD-based Aeroservoelasticity
No full textAn analysis procedure for the combined problem of control algorithm and aeroelastic system which is based on the computational fluid dynamics(CFD) technique has been developed. The aerodynamic forces in the transonic region are calculated from the transonic small disturbance(TSD) theory. An linear quadratic regulator(LQR) controller is designed to suppress the transonic flutter. The optimal control gain is estimated by solving the discrete-time Riccati equation. The system identification technique rebuilds the CFD-based aeroelstic system in order to form an adequate system matrix which involved in the discrete-time Riccati equation. Finally the controller, that is constructed on the basis of system identification technique, is used to suppress the flutter phenomenon of the airfoil with attached store. This approach, that is, the CFD-based aeroservoelasticity design, can be utilized for the development of effective flutter controller design in the transonic region.This rewearch is supported by FVRC(flight vehicle research center) by the Agency for Defence Development, Korea. Authors are grateful for their supports
A Study on the Parametric Rules for Automatic Description System of Han-ok Library based on Open BIM
No full textIn open BIM study for 3D information exchange of Han-ok, a Han-ok library using IFC-XML have been developed. It provides environment that enables data exchange between different BIM tools by containing geometry data and XML link data in IFC and parametric data in XML, to supports Han-ok design. However, to produce Han-ok members with XML, a specialist must perform coding, and it takes a long time for coding one member of Han-ok because of the hard coding method. To improve this issue, a IFC-XML HADS(Han-ok Automatic Description System) is under development for non-experts, and this study concerns parametric rules of the joint connection model which is to be applied to HADS. This study will help define parametric data of Han-ok's joint connection as IFC-XML base��� ��������� ��������������� ��������������������������� ��������� ��������� ������ ��������� ���������. ������������:10������������ B0
Influence of Zn and Mg Alloying on the Corrosion Resistance Properties of Al Coating Applied by Arc Thermal Spray Process in Simulated Weather Solution
No full textIn this study, Al–Zn and Al–Mg coatings were deposited on steel substrates by an arc thermal spray process. X-ray diffraction and scanning electron microscopy were used to characterize the deposited coatings and corrosion products. Open circuit potential (OCP), electrochemical impedance spectroscopy, and potentiodynamic studies were used to assess the corrosion characteristics of these coatings after exposure according to the Society of Automotive Engineers (SAE) J2334 solution of varying durations. This solution simulates an industrial environment and contains chloride and carbonate ions that induce corrosion of the deposited coatings. However, the Al–Mg alloy coating maintained an OCP of approximately − 0.911 V versus Ag/AgCl in the SAE J2334 solution even after 792 h of exposure. This indicates that it protects the steel sacrificially, whereas the Al–Zn coating provides only barrier-type protection through the deposition of corrosion products. The Al–Mg coating acts as a self-healing coating and provides protection by forming Mg6Al2(OH)16CO3 (Al–Mg layered double hydroxides). Mg6Al2(OH)16CO3 has interlocking characteristics with a morphology of plate-like nanostructures and an ion-exchange ability that can improve the corrosion resistance properties of the coating. The presence of Zn in the corrosion products of the Al–Zn coating allows dissolution, but, at the same time, Zn5(OH)6(CO3)2 and Zn6Al2(OH)16CO3 are formed and act to reduce the corrosion rate.This work was supported by the research fund of Hanyang University (No. HY-2014-P)
플렉서블 표시패널
No full textA flexible display panel includes a bending area and a surrounding area adjacent to the bending area. The barrier layer includes first silicon nitride layers and first silicon oxide layers which are overlapped with the bending area. The first silicon nitride layers and the first silicon oxide layers are stacked alternately. Each of the first silicon nitride layers may have a thickness less than or equal to about 400 Å, and each of the first silicon oxide layers may have a thickness less than or equal to about 650 Å
Time and cold joint effect on chloride diffusion in concrete containing GGBFS under various loading conditions
No full textThe stress due to volume change causes cracking in concrete, so that construction joint is intentionally prepared for an efficient construction and crack controlling in mass concrete structure. Cold joint means a weak joint area which may occur due to imperfect treatment of pre-placed concrete surface and delayed concrete delivery. Many researches have been performed for a quantitative evaluation of chloride ingress in cold joint concrete, which puts an emphasis on the more rapid penetration of chloride ions. The applied loading condition is one of the major reasons for concrete cracking and it also has a great effect on chloride penetration before the stage of cracking. Steel corrosion in concrete is accelerated when concrete cover has unsound area such as crack and cold joint. Chloride diffusion behavior varies with reduction of porosity and enhancement of hydrates, so called time effect on chloride diffusion. The effect of time and of cold joint on chloride diffusion is an important parameter for quantitative durability design for RC (Reinforced Concrete) structures exposed to various loading conditions. This paper investigates changes in chloride diffusion coefficient in cold joint concrete considering time effect and various loading conditions. Concrete samples with 0.6 of w/b (water to binder) and 40% replacement ratio of GGBFS (Ground Granulated Blast Furnace Slag) were prepared, and the chloride diffusion coefficients were measured for 1 year-cured concrete considering tensile and compressive loading conditions. The results were analyzed with the previous results in 91 days-cured concrete for evaluation of time effect. In the work, the time dependent chloride diffusion behaviors were quantitatively evaluated and discussed considering various effects of GGBFS, tensile and compressive stress levels, and cold joint
miRNA regulation of cytotoxic effects in mouse Sertoli cells exposed to nonylphenol
No full textBackground: It is known that some environmental chemicals affect the human endocrine system. The harmful effects of endocrine disrupting chemical (EDC) nonylphenol (NP) have been studied since the 1980s. It is known that NP adversely affects physiological functions by mimicking the natural hormone 17 beta-estradiol. In the present study, we analyzed the expression of miRNAs and their target genes in mouse Sertoli TM4 cells to better understand the regulatory roles of miRNAs on Sertoli cells after NP exposure. Methods: Mouse TM4 Sertoli cells were treated with NP for 3 or 24 h, and global gene and miRNA expression were analyzed using Agilent mouse whole genome and mouse miRNA v13 arrays. Results: We identified genes that were > 2-fold differentially expressed in NP-treated cells and control cells (P < 0.05) and analyzed their functions through Gene Ontology analysis. We also identified miRNAs that were differentially expressed in NP-treated and control cells. Of the 186 miRNAs the expression of which differed between NP-treated and control cells, 59 and 147 miRNAs exhibited 1.3-fold increased or decreased expression at 3 and 24 h, respectively. Network analysis of deregulated miRNAs suggested that Ppara may regulate the expression of certain miRNAs, including miR-378, miR-125a-3p miR-20a, miR-203, and miR-101a, after exposure to NP. Additionally, comprehensive analysis of predicted target genes for miRNAs showed that the expression of genes with roles in cell proliferation, the cell cycle, and cell death were regulated by miRNA in NP-treated TM4 cells. Levels of expression of the miRNAs miR-135a* and miR-199a-5p were validated by qRT-PCR. Finally, miR-135a* target gene analysis suggests that the generation of reactive oxygen species (ROS) following exposure to NP exposure may be mediated by miR-135a* through regulation of the Wnt/beta-catenin signaling pathway. Conclusions: Collectively, these data help to determine NP's actions on mouse TM4 Sertoli cells and increase our understanding of the molecular mechanisms underlying the adverse effects of xenoestrogens on the reproductive system.This work was supported an Eco-Technopia 21 project grant from the Ministry of Environment (Development of Decision Method of Chromosomal Abnormality in Reproductive System by Toxic Substances at the Korea Institute of Toxicology)
Accuracy and Reliability of Length Measurements on Three-Dimensional Computed Tomography Using Open-Source OsiriX Software
No full textThere is a growing interest in three-dimensional computed tomography (3D-CT) as a research tool for the study of bone, joint anatomy, and kinematics. However, when CT data are processed and handled manually using image processing programs to yield 3D image and coordinate value, systematic and random errors should be validated. We evaluated the accuracy and reliability of length measurement on CT with OsiriX software. 3D-CT scans were made of 14 frozen pig knees with five transosseous holes in the metaphyseal portion of femur. The lengths between tunnel orifices were measured using Mitutoyo Digimatic digital calipers to establish the gold standard, and with the OsiriX program in 3D multi-planar reformatting mode for comparison. All measurements were recorded by a principal (replicate 1, trial 1) and a secondary observer (replicate 2, trial 1) and were repeated once by each observer (trial 2). The mean differences between OsiriX and real measurements were less than 0.1 mm in both replicates, and maximum differences were less than 0.3 mm. There were no significant differences between the replicates and real measurements (p = 0.544 and 0.622 for replicates 1 and 2, respectively). The intraclass correlation coefficients (ICC) were very high between trials and between replicates (ICC = 0.998 and 0.999, respectively). For kinematic analysis of the knees, length measurements on 3D-CT using OsiriX program can be used as alternatives to real measurements with less than 0.3-mm accuracy and very high reliability.
온도 적응형 커패시터 블록 및 이를 이용한 온도 보상 수정발진기
No full textA temperature-adaptive capacitor array used in a TCXO so that the TCXO effectively conducts temperature-compensating in the resonant frequency without the non-monotonicity while a smaller silicon area is used in producing the capacitor array. A number of capacitor arrays allocated in two capacitor banks. Each of the capacitor arrays comprises two or more unit cells, and in turn each unit cell consists of a unit capacitor and a switching element, respectively. All of unit capacitors included in the capacitor arrays are connected each other through a decoder assembly to provide a crystal oscillator with a load capacitance. The unit capacitors belonging to one of the capacitor arrays have the same capacitance with each other. Two unit capacitors belonging to different capacitor arrays, however, have different capacitances from each other. The capacitance of the unit capacitors belonging to each capacitor array is set in consideration of control preciseness required in compensating a frequency deviation in the resonant frequency of the crystal oscillator as the temperature varies in at least a portion of a practical temperature range, within which the crystal oscillator operates
Test based reliability quantification method for a safety critical software using finite test sets
No full textSoftware is currently used within nuclear power plants (NPPs) to digitalize many instrumentation and control (I&C) systems. To guarantee the safety of the NPP, the reliability of the software must be properly quantified. In this study, we propose a novel method for software reliability quantification. The method identifies and arranges possible internal states of the software that can occur in actual use. Based on a specific internal state, possible input sets (combination of single values of each input variable) are applied sequentially. In this process, the assigned range of each variable, correlation between variables, characteristics of analog-to-digital converter (ADC), and plant dynamics are considered to identify the possible states of each variable. The effectiveness of the proposed method is demonstrated via a case study for a trip logic in a reactor protection system (RPS). Compared with existing test-based methods, the proposed method can shorten test execution time and eliminate uncertainties derived from random sampling of input values from the operation profile. Moreover, this method can provide a number of test sets required for an exhaustive testing
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