• Magazine of the Korea Concrete Institute
• /
• v.17 no.5 s.88
• /
• pp.51-57
• /
• 2005

• Journal of the Korea Concrete Institute
• /
• v.21 no.3
• /
• pp.327-335
• /
• 2009

In the seismic region, non-ductile structures often form soft story and exhibit brittle collapse. However, structure demolition and new structure construction strategies have serious problems, as construction waste, environmental pollution and popular complain. And these methods can be uneconomical. Therefore, to satisfy seismic performance, so many seismic retrofit methods have been investigated. There are some retrofit methods as infill walls, steel brace, continuous walls, buttress, wing walls, jacketing of column or beam. Among them, the infilled frames exhibit complex behavior as follows: flexible frames experiment large deflection and rotations at the joints, and infilled shear walls fail mainly in shear at relatively small displacements. Therefore, the combined action of the composite system differs significantly from that of the frame or wall alone. Purpose of research is evaluation on the seismic performance of infill walls, and improvement concept of this paper is use of SHCCs (strain-hardening cementitious composites) to absorb damage energy effectively. The experimental investigation consisted of cyclic loading tests on 1/3-scale models of infill walls. The experimental results, as expected, show that the multiple crack pattern, strength, and energy dissipation capacity are superior for SHCC infill wall due to bridging of fibers and stress redistribution in cement matrix.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.2
• /
• pp.11-16
• /
• 2006

An experimental study of the transonic flows over NACA and double wedge airfoils was conducted with a shock tube. The configuration of test section with a slotted wall and chamber was designed and tested to minimize wall and reflected shock wave effects and use the shock tube as simple and less costly wind tunnel generating the relatively high Reynolds numbers transonic flow. Transonic airfoil flows at hot gas Mach numbers of 0.80~0.84, Reynolds number of about $1.2{\times}10^6$ on airfoil chord length and angles of attack of $0^{\circ}$ and $2^{\circ}$ were visualized with the shadowgraph method. The shock wave profiles on the airfoils were compared with the corresponding results from the conventional transonic wind tunnel tests. The experimental results showed that present shock tube exhibited the proper performance characteristics as transonic wind tunnel for tested Mach number range and airfoils.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.3
• /
• pp.203-210
• /
• 2014

In this study, the hydrodynamic characteristics of Weis-Fogh type water turbine were calculated by the advanced vortex method. The wing (NACA0010 airfoil) and both channel walls were approximated by source and vortex panels, and free vortices are introduced away from the body surfaces. The distance from the trailing edge of the wing to the wing axis, the width of the water channel and the maximum opening angle were selected as the calculation parameters, the important design factors. The maximum efficiency and the power coefficient for one wing of this water turbine were 26% and 0.4 at velocity ratio U/V=2.0 respectively. The flow field of this water turbine is very complex because the wing moves unsteadily in the channel. However, using the advanced vortex method, it could be calculated accurately.

• Korean Journal of Plant Taxonomy
• /
• v.32 no.3
• /
• pp.257-292
• /
• 2002

Morphological characters of sections Foetidae(one taxon), Arenariae(one taxon) and Multiflorae(six taxa) of genus Carex(Cyperaceae) were reexamined. The epidermal patterns of perigynium, achene and leaf were investigated using by a scanning electron microscope(SEM) and a light microscope(LM). Morphological characters, such as length and width of stem, leaf, leaf sheath, bract, spike, scale, perigynium and beak of perigynium, length of spike peduncle, size and frequency of stomatal complex of leaf, number of bract, shape of stem transection, scale and apex of scale, beak and base of perigynuim, achene, epidermal cell and cell wall of perigynium, achene, leaf epidermal patterns(fundamental epidermal cell and cell wall, silica body, subsidiary cell), hair, papillae present/absent of perigynium, and leaf were useful for the identification of observed eight taxa. According to the current study, examined eight taxa of sections Foetidae, Arenariae and Multiflorae were distinct from each other with respect to length and width of stem, leaf, bract, perigynium, perigynium beak, length of spike peduncle, shape of bract, scale and apex of scale, perigynium, perigynium beak, hair presence/absence of perigynium and leaf. A key based on data was presented here.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.41 no.11
• /
• pp.709-717
• /
• 2017

In this study, a model of two-stage Weis-Fogh type water turbine model is proposed, the hydrodynamic characteristics of this water turbine model are calculated by the advanced vortex method. The basic conditions and the motion of each wing are the same as that of the single-stage model previously proposed by the same author. The two wings (NACA0010 airfoils) and both channel walls are approximated by source and vortex panels, and free vortices are introduced from the body surfaces. The distance between the front wing axis and the rear wing axis, and the phase difference between the motion of the two wings, which is in phase and out of phase are set as the calculation parameters. For each case, the unsteady flow fields, pressure fields, force coefficients, and efficiency of the two wings are calculated, and the hydrodynamic characteristics of the proposed water turbine model are discussed.

• Journal of Aerospace System Engineering
• /
• v.3 no.2
• /
• pp.1-11
• /
• 2009

A structural modelling for study on dynamic characteristics of tapered composite aircraft wings in the form of thin-walled beam is presented. The proposed structural model includes effects of transverse shear flexibility exhibited by the advanced composite materials and warping restraint characterizing elastic anisotropy and induced structural couplings. The complex effects of these factors could have a role in more efficient analysis on those structural models.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.09a
• /
• pp.1164-1169
• /
• 2009

Piled raft foundation is commonly used for structure on deep soft soil deposit rather than end bearing piles to control differential settlement. However, it is still expensive for light weight structures. Wing-wall type foundation has been successfully applied to reduce average settlement for light weight structure. This study will further investigate this type of foundation using bench scale experiments on clay and sand. Numerical analysis and approach method are used to verify load settlement curve of wing-wall foundation on experimentally study. Furthermore, normalized settlement curves are applied to define prediction of settlement on wing-wall foundation. In the result settlement on wing-wall foundation can be effectively done by increasing the length of wall instead of number of walls and equation for calculating average settlement can be derived using normalized load settlement curve.

• The Korean Journal of Mycology
• /
• v.47 no.4
• /
• pp.417-425
• /
• 2019

Biocontrol agents (BCAs) are widely used to protect plants from diverse biotic and abiotic stresses in agricultural and ecological fields. Among the various microbes, many subspecies of the gram-positive genus, Bacillus, have been successfully industrialized as eco-friendly biological pesticides and fertilizers. In the current study, we demonstrated that Bacillus thuringiensis C25 exhibited antagonistic effects on the mycelial growth of Rosellinia necatrix, a fungal phytopathogen. Scanning electron microscopy analysis revealed that B. thuringiensis C25 degraded the cell wall structures of R. necatrix mycelia. In the functional genomic analysis of B. thuringiensis C25, we annotated 5,683 genes and selected the gene sets that potentially encoded fungal cell wall degrading enzymes (CWDEs). The growth inhibition effects on R. necatrix were highly correlated with the transcriptional activity of the mycelial cell wall degrading genes of B. thuringiensis C25. The transcript levels of CWDEs, including CshiA, B, and Glycos_transf_2 genes in B. thuringiensis C25, were enhanced following co-cultivation with R. necatrix. In conclusion, our study suggested that B. thuringiensis C25 could serve as a suitable candidate for controlling R. necatrix and could facilitate elucidating the mechanisms underlying the antifungal activities of BCAs against phytopathogens.

• Korean Journal of Construction Engineering and Management
• /
• v.9 no.3
• /
• pp.118-125
• /
• 2008

In Korea, five days per week system, duration reduction bidding system, and post sale system have recently stimulated an interest in productivity improvement in construction project. However, analysis result of productivity in Korean construction industry found that the productivity is too low. APC (Architectural PC) is alternative of reveal wall and parapet in apartment housing prcjects and is used abroad broadly because of duration reduction for productivity improving. APC is used as external curtain wall in Dubai, North America, and Southeast Asia. Therefore, it is proposed that necessary to Introduce APC in Korea. The objective of this study is to draw up introduction of APC in apartment housing projects. We analysed the feasibility of the use of APC. The survey results reported that APC would be able to improve the productivity in the eight productivity factors.