• Structural Engineering and Mechanics
• /
• v.53 no.1
• /
• pp.147-158
• /
• 2015

Elements used in steel structures may be considered as an assembly of number of thin flat walls. Local buckling of these members can limit the buckling capacity of axial load resistance or flexural strength. We can avoid a premature failure, caused by effects of local buckling, by limiting the value of the wall slenderness which depend on its critical buckling stress. According to Eurocode 3, the buckling stress is calculated for an internal wall assuming that the latter is a simply supported plate on its contour. This assumption considers, without further requirement, that the two orthogonal walls to this wall are sufficiently rigid to constitute fixed supports to it. In this paper, we focus on webs of steel profiles that are internal walls delimited by flanges profiles. The objective is to determine, for a given web, flanges dimensions from which the latter can be considered as simple support for this web.

• Proceedings of the Korea Technology Innovation Society Conference
• /
• 1999.11c
• /
• pp.557-575
• /
• 1999

The task evaluating science and technology is becoming more important in every country trying to develop and improve overall national R&D capability in an effort to sustain national prosperity and public welfare. However, the way in which evaluation organisation is approached in each country may differ from nation to nation reflecting national R&D systems and S&T policies as well as the specific roles of scientists and policy- makers at various levels. Over the past two decades or so, Korean evaluation system has been transplanted form the West and they modified, In addition, Korea borrowed elements from the Japanese. Whether such systems have been well rooted in our specific circumstances is a critical question. In this context, it would be meaningful to diagnoses the current Korean evaluation system and also makes some suggestions for improving this system. For this purpose, this paper also attempts to approach to the theoretical aspects of evaluation as a starting-point.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.8
• /
• pp.2758-2765
• /
• 2010

A technology transfer from public research centers or national universities to a company is an increasing phenomenon. The purpose of this study is thus to identify the major evaluation criteria of technology transfer from a company viewpoint and establish the importance weights of criteria through 2 level AHP analysis. First, 12 critical elements are extracted from previous studies and professional interview and these elements are tied into 4 factors; technological factor, organizational factor, environmental factor, and strategic factor. The results of AHP analysis show that strategic factor is more important and 'the growth of the technology' in the strategic factor is the most important element. This study will be used usefully when researchers in public research centers or national universities try to develop a technology considering a technology transfer to the other company.

• Molecules and Cells
• /
• v.44 no.11
• /
• pp.805-829
• /
• 2021

CCCTC-binding factor (CTCF) critically contributes to 3D chromatin organization by determining topologically associated domain (TAD) borders. Although CTCF primarily binds at TAD borders, there also exist putative CTCF-binding sites within TADs, which are spread throughout the genome by retrotransposition. However, the detailed mechanism responsible for masking the putative CTCF-binding sites remains largely elusive. Here, we show that the ATP-dependent chromatin remodeler, chromodomain helicase DNA-binding 4 (CHD4), regulates chromatin accessibility to conceal aberrant CTCF-binding sites embedded in H3K9me3-enriched heterochromatic B2 short interspersed nuclear elements (SINEs) in mouse embryonic stem cells (mESCs). Upon CHD4 depletion, these aberrant CTCF-binding sites become accessible and aberrant CTCF recruitment occurs within TADs, resulting in disorganization of local TADs. RNA-binding intrinsically disordered domains (IDRs) of CHD4 are required to prevent this aberrant CTCF binding, and CHD4 is critical for the repression of B2 SINE transcripts. These results collectively reveal that a CHD4-mediated mechanism ensures appropriate CTCF binding and associated TAD organization in mESCs.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.10
• /
• pp.179-186
• /
• 2019

Based on the characteristics of the weapon system, a government-funded research institute or a defense industry company is selected as the R&D supervision institution. On the other hand, research for the selection of a R&D supervision institution has not been conducted actively. This paper proposes a methodology for selecting R&D supervision institutions, such as procedure and indices. First, candidates of the index were obtained using data investigation and consulting, and five indices were deduced using Delphi. The weight of the indices was set using AHP. The high element consisted of 'Technical elements' and 'Business element'. The low element of 'Technical elements' consisted of 'Possession and readiness of critical technology' and 'Experience of similar R&D'. The low element of 'Business element' consisted of 'Base circumstance of the project', 'Risk management', and 'Will for the project'. The total weights of the indices were 'Possession and readiness of critical technology' 0.405, 'Experience of similar R&D' 0.297, 'Base circumstance of the project' 0.124, 'Risk management' 0.127, and 'Will for the project' 0.047. The indices were applied to the 00 weapon system and the result was deduced.

• Computers and Concrete
• /
• v.14 no.6
• /
• pp.635-656
• /
• 2014

A rational estimation of moisture distribution in structural concrete is vital for predicting the possible extent and rate of progression of impending degradation processes. The paper proposes a numerical scheme for analysing the evolution of moisture distribution in concrete subjected to wetting-drying exposure caused by intermittent periods of rainfall. The proposed paradigm is based on the stage wise implementation of non-linear finite element (FE) analysis, with each stage representing a distinct phase of a typical wet-dry cycle. The associated boundary conditions have been constituted to realize the influence of various meteorological elements such as rain, wind, relative humidity and temperature on the exposed concrete surface. The reliability of the developed scheme has been demonstrated through its application for the simulation of experimentally recorded moisture profiles reported in published literature. A sensitivity analysis has also been carried out to study the influence of critical material properties on simulated results. The proposed scheme is vital to the service life modelling of concrete structures in tropical climates which largely remain exposed to the action of alternating rains.

• Corrosion Science and Technology
• /
• v.3 no.5
• /
• pp.179-186
• /
• 2004

Recently the alloy development of duplex stainless steel has been done. On this study we studied the effect of the corrosion resistance according to the composition variety of C, Cr, N in the alloy elements of duplex stainless steel. materials which have below 0.1[mm/year] corrosion rate enable to use for corrosion-resisting materials, generally. On this experiment we inspected the effect of the composition variety of C, Cr, N in duplex stainless steel and the heat treatment, which the condition was the water quenching after the heat treatment for 1hr. The experiment was done on the basis of the ASTM G48A test, Critical pitting temperature(CPT), and ASTM G-61(Electrochemical tests for cyclic polarization).

• Structural Engineering and Mechanics
• /
• v.35 no.5
• /
• pp.617-630
• /
• 2010

Different types of moment resisting connections are commonly used to transfer the induced seismic moments between frame elements in an earthquake resisting structure. The local connection behavior may drastically affect the global seismic response of the structure. In this study, the finite element and experimental seismic investigations are implemented on two frequently used connection type to evaluate the local behavior and to reveal the failure modes. An alternative connection type is then proposed to eliminate the unfavorable brittle fracture modes resulted from probable poor welding quality. This will develop a reliable predefined ductile plastic mechanism forming away from the critical locations. Employing this technique, the structural reliability of the moment resisting connections shall be improved by achieving a controllable energy dissipation source in form of yielding of the cover plates.

• Wind and Structures
• /
• v.16 no.5
• /
• pp.457-476
• /
• 2013

This paper presents theoretical background for a semi-empirical, mathematical model of critical vortex excitation of slender structures of compact cross-sections. The model can be applied to slender tower-like structures (chimneys, towers), and to slender elements of structures (masts, pylons, cables). Many empirical formulas describing across-wind load at vortex excitation depending on several flow parameters, Reynolds number range, structure geometry and lock-in phenomenon can be found in literature. The aim of this paper is to demonstrate mathematical background of the vortex excitation model for a theoretical case of the structure section. Extrapolation of the mathematical model for the application to real structures is also presented. Considerations are devoted to various cases of wind flow (steady and unsteady), ranges of Reynolds number and lateral vibrations of structures or their absence. Numerical implementation of the model with application to real structures is also proposed.

• Journal of the Korean Society of Mechanical Technology
• /
• v.13 no.3
• /
• pp.25-30
• /
• 2011

Flow control of flow field is essential to design efficient elements relating to fluid machineries. In this study, flow characteristics of rectangular prism with center gap through-flow at different aspect ratio was investigated to flow control. It was used a FLUENT 6.3 version to study flow field. It was found that the through-flow disturbs the development of vertical velocity component and decreased the vortex size and critical value of a rapid change in pressure coefficient distribution.