• Wind and Structures
• /
• v.10 no.1
• /
• pp.61-82
• /
• 2007

This paper presents a novel finite element (FE) model for analyzing coupled flutter of long-span bridges using the commercial FE package ANSYS. This model utilizes a specific user-defined element Matrix27 in ANSYS to model the aeroelastic forces acting on the bridge, wherein the stiffness and damping matrices are expressed in terms of the reduced wind velocity and flutter derivatives. Making use of this FE model, damped complex eigenvalue analysis is carried out to determine the complex eigenvalues, of which the real part is the logarithm decay rate and the imaginary part is the damped vibration frequency. The condition for onset of flutter instability becomes that, at a certain wind velocity, the structural system incorporating fictitious Matrix27 elements has a complex eigenvalue with zero or near-zero real part, with the imaginary part of this eigenvalue being the flutter frequency. Case studies are provided to validate the developed procedure as well as to demonstrate the flutter analysis of cable-supported bridges using ANSYS. The proposed method enables the bridge designers and engineering practitioners to analyze flutter instability by using the commercial FE package ANSYS.

• Journal of Electrochemical Science and Technology
• /
• v.5 no.2
• /
• pp.58-64
• /
• 2014

The surface of an ordered mesoporous silica (OMS) was functionalized using 1H,1H,2H,2H-perfluorooctyltrimethoxysilane at $20^{\circ}C$ and $60^{\circ}C$. It was shown that only elevated temperature allows lyophobic properties on the walls of OMS, eventually preventing pore flooding with nonaqueous electrolytes. The functionalized OMSs (OMS-F) were characterized with various techniques: wettability test, $N_2$ sorption measurement, high-resolution transmission electron microscopy (HR-TEM). Cathodes of $10mg/cm^2$ loading were prepared with a commercial Pt/C catalyst and polyvinylidene fluoride (PVDF, 2.5 wt.%) binder using a typical doctor blade method on a commercial gas diffusion layer (GDL) in the presence or in the absence of OMS-F additives. Subsequent discharge-charge curves were taken in a 1M LiTFSI-TEGDME electrolyte at 60oC in pure oxygen atmosphere. It was found that the discharge capacity was significantly affected by OMS-F: 5 wt.% of additive extended discharge capacity by a factor 1.5. On the other hand, a similar OMS material but synthesized at $20^{\circ}C$ did not show lyophobic properties and deteriorated cathode capacity.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.19 no.37
• /
• pp.127-136
• /
• 1996

Due to the development of technology, urbanization, industrialization, etd. at modern times, even the individual view of value has changed in variety. That means the change of each consumcer's life-style and even that of propensity to consume. In that regard, the modern, commercial space became to be increasingly included to specialization and complication. Such specialization and complication of the commercial space can be thought to be a positive response of enterprises to satisfy the needs or desire of consumers who become diversified. In this study, some new models in the method of the planning and designing of the S.I.P(Shop Identity Program). intended to research into as follows ; - As the background of the advent of the multi-used shopping complex, changes in consumer life-style and propensity to consume according to social and economical changes were intended to be studied through various statistical data literature. - For the study of the characteristics, constituent conditions, and planning operation of the future multi used shopping complex in the marketing aspect of enterprises, it was intended to study centered on the theory of consumer behavior and that of retail marketing. - In the process of the spatial design of the multi-used shopping complex, it was tried that a designing process to materialize a target of the discrimination and orderly arrangement of stores be progressed. In the process of materializing a target based on both corporate image and 'brand' image in designing.

• Journal of the Korean Professional Engineers Association
• /
• v.36 no.4
• /
• pp.54-57
• /
• 2003

• Korean Architects
• /
• s.654
• /
• pp.107-109
• /
• 2023

• Journal of Ocean Engineering and Technology
• /
• v.16 no.1
• /
• pp.36-40
• /
• 2002

Despite the frequent use of ring-stiffened cylinders as a submarine pressure hull or members of various types of offshore structure, their ultimate strength analysis methods have not been well established because of their complex structural characteristics. This paper has established the method how to use commercial softwares based on the finite element method to implement the ultimate strength analysis of ring-stiffened cylinders covering both types of initial imperfection, i.e. initial deformation and initial stress by combining two separately offered functions of common commercial finite element softwares, linear elastic buckling analysis and nonlinear stress analysis. Developed method was applied to one of the world-widely used commercial softwares. ABAQUS for the analysis of ring stiffened cylinders. This paper ends with some useful information about the imperfection sensitivity of ultimate strength ring stiffened cylinders.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2001.05a
• /
• pp.114-118
• /
• 2001

Despite the frequent use of ring-stiffened cylinders as a submarine pressure hull or members of various types of offshore sutructures, their ultimate strength analysis methods have not been well established because of their complex structural characteristics. This paper has established the method how to use commercial softwares based on the finite element method to implement the ultimate strength analysis of ring-stiffened cylinders covering both types of initial imperfections, I. e. initial deformation and initial stress by combining two separately offered functions of common commercial finite element softwares, linear elastic buckling analysis and nonlinear stress analysis. Developed method was applied to one of the world-widely used commercial softwares, ABAQUS for the analysis of ring-stiffened cylinders. This paper ends with some useful information about the imperfection sensitivity of ultimate strength of ring-stiffened cylinders.

• Journal of Ocean Engineering and Technology
• /
• v.15 no.2
• /
• pp.120-123
• /
• 2001

Despite the increasing necessity of accurate estimation of ring-stiffened cylinders'ultimate strength, the complex structural behavior of cylinders has made their design mainly depend on empirical formulas mostly based on limited test data rather than theoretical background. This paper has developed the imperfection method which enables the ultimate strength analysis of buckling-sensitive structures by combining two separate functions covered by common commercial finite element softwares, which are linear elastic buckling analysis and nonlinear stress analysis. Developed method was applied to two of the world most renowned softwares, MSC/NASTRAN and ABAQUS, for the analysis of ring-stiffened cylinders and unexpectedly big difference in their analysis results was found. This tells that many widely used commercial softwares have their different strong points and weak points and the choice of commercial software should be cautiously made after thorough inspection. This paper ends with some useful information about which of the two aforementioned softwares is more respectively for the linear elastic buckling analysis and the ultimate strength analysis of ring-stiffened cylinders.

• Journal of Korea Technology Innovation Society
• /
• v.2 no.2
• /
• pp.275-289
• /
• 1999

This study aims at investigating the stylized facts of the complex system products innovation in Korea. It reviewed the preceeding studies on the innovation patterns of complex system products and selected the issues to be examined in investigating Korean case. In addition, the stylized facts of innovation patterns of Korean complex system products were suggested. The peculiar characteristics of Korean cases are as follows: Korea has succeeded in integrating foreign technologies and components into commercial complex system products and in substituting the foreign system products in the domestic market. However, it faces a great difficulty in upgrading the products to the next generation. It lacks capabilities which facilitate the evolution of system products competing in the world market.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.11
• /
• pp.87-93
• /
• 2020

A key component of aviation safety is to eliminate the errors in commercial aircraft air data systems to ensure stable aviation operation. Although the technical aspects such as the maintenance and inspection play a pertinent role, human errors are expected to have a similar or even larger influence on the aviation safety. Aviation maintenance and inspection tasks are often performed by a complex organization, in which individuals perform a variety of tasks in an environment involving time pressure, sparse feedback, and complex conditions. These situational characteristics, combined with the general tendency of human error, may lead to various types of errors, which may have critical consequences such as accidents and loss of life. For instance, if an amber message "IAS DISAGREE" is displayed on the primary flight display while the aircraft is rolling on the runway to takeoff, the crew immediately performs a rejected takeoff operation and troubleshoots the air data system. This paper proposes alternative approaches to address the occurrence of defects due to the human factors involved in the practical processes of the air data system of commercial aircraft.