• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.81-88
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• 2018

The present study evaluated the effective arrangement approach of transverse reinforcement in the jacket section for seismic strengthening of reinforced concrete columns. To simulate the full-scale columns, the section dimensions were determined as $450{\times}450mm$ for non-seismic existing columns and $750{\times}750mm$ for section enlargement strengthening columns. Over-lapped channel-shape bars and prefabricated bar units were proposed for closed-hoops in the jacket section, and conventional cross-ties anchored into existing columns and V-ties were considered for the supplementary ties. Test results showed that the axial capacity of the existing column and section enlargement columns with over-lapped channel-shape hoops was similar to the nominal strength calculated using ACI 318-14 procedure whereas the section enlargement column with prefabricated bar units possessed 1.25 times higher axial capacity than the nominal prediction. Furthermore, the axial ductility ratio of the section enlargement column with prefabricated bar unit was 139% higher than that of the existing column despite the potential size effect on ductility of concrete. Thus, it can be concluded that the developed prefabricated bar unit technique is practically useful for preventing the premature buckling of longitudinal reinforcement and confining core concrete in the section enlargement strengthening columns.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.2
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• pp.331-337
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• 1994

The scatting problem by E-polarized plane wave with obique incidence on a tapered resistive strip grating with zero resistivity(perfectly conducting) at strip-edges is analyzed by the method of moments in the spectral domain. Then the induced surface current density on the strip is expanded in a series of Chebyshev polynomials of the second kind. The expasion coefficients are calculated numerically in the spectral domain, the numerical results of the geometric-optical reflection coefficient for the tapered resistivity in this paper are compared with those for the existing uniform resistivity. And the position of sharp variation points in the magnitude of the geometric-optical reflection coefficient can be moved by varying the incident angle and the strip spacing, It is found out that these sparp variation points are due to the transition of higher mode between the propagation mode and the evanescent mode.

• Korean journal of applied entomology
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• v.34 no.4
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• pp.344-349
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• 1995

To isolate naturally occurring novel Bacillus thuringiensis strains for useful pest con시 agents, A total of 64 isolates of B. thuringiensis producing spore and crystal were obtained from 583 soil samples in Korea. Toxicity of isolates was assayed against Lepidoptera (Bombyx ori), Diptera (Culex pipens) and Coleoptera (Sitophilus oryzae), respectively. The results showed that B. thuringiensis isolates toxic Lepidoptera are 42.2% , both Lepidoptera and Diptera are 31.3% and Diptera are 20.3%, demonstrating that spectrum of insecticidal activity of B. thuringiensis isolates is various. But no B. thuringiensis isolates have toxicity against Coleoptera.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.6
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• pp.81-90
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• 2011

The purpose of this study was to investigate the seismic performance of reinforced concrete bridge columns with interlocking circular hoops. Three interlocking columns were tested under a constant axial load and a quasistatic, cyclically reversed horizontal load. A computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) was used for the analysis of reinforced concrete structures. The used numerical method gives a realistic prediction of performance throughout the loading cycles for several test specimens investigated. Based on the experimental and analytical results, design recommendations are presented to improve the existing practice in the design and construction of reinforced concrete bridge columns with interlocking circular hoops.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.3
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• pp.77-82
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• 2023

In this paper, TM(tranverse magnetic) electromagnetic scattering problems for resitive strip grating between grounded double dielectric layers are analyzed by using the FGMM(fourier galerkin moment method) and PMM(point matching method) known as a numerical method of electromagnetic field. The boundary conditions are applied to obtain the unknown field coefficients, the resistive boundary condition is applied to analysis of resistive strip. Overall, when the unoform resistivity decreased, the magnitude of the current density induced in the resistive strip increased, and the reflected power also increased. Also, as the thickness and relative permittivity of the double dielectric layers increased, the overall reflected power increased. The numerical results obtained by using the numerical methods of FGMM and PMM to the structure proposed in this paper agree very well.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.6
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• pp.512-519
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• 2013

It is important to understand the vibrating behavior of plate structures for its many engineering applications. In this study, the vibration characteristics of strip plates that have finite width and infinite length are investigated theoretically and numerically. The waveguide finite element(WFE) approach, which is an effective tool for studying waveguide structures, is used in this study. The WFE method requires only a cross-sectional finite element model, and uses theoretical harmonic solutions to assess wave propagation along the longitudinal direction. First, WFE results for a simple strip plate are compared with the theoretical results(i.e., dispersion diagrams and point mobilities) to validate the numerical model. Then, in the numerical analysis, different numbers of longitudinal stiffeners are included in the plate model to investigate the effects of stiffeners in terms of the dispersion curves and mobilities. Finally, the dispersion curves of a stiffened double plate are obtained to examine the characteristics of its wave propagation.

• Journal of Advanced Navigation Technology
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• v.15 no.3
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• pp.349-354
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• 2011

In this paper, H-polarized scattering problems by a resistive strip grating with zero resistivity at strip-edges over a grounded dielectric plane according to the strip width and grating period, the relative permittivity and thickness of a dielectric layer, and incident angles of a transverse electric (TE) plane wave are analyzed by applying the Fourier-Galerkin Moment Method (FGMM). The tapered resistivity of resistive strips has zero resistivity at strip edges, then the induced surface current density on the resistive strip is expanded in a series of Chebyshev polynomials of the second kind as a orthogonal ploynomials. The sharp variations of the reflected power are due to resonance effects were previously called wood's anomallies, the numerical results for the reflected power are compared with those of uniform resistivity in the existing papers.

• Applied Chemistry for Engineering
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• v.3 no.2
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• pp.240-246
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• 1992

The electronic structure of oxygen atom of cation-exchanged zeolite was investigated by utilizing X-ray photoelectron spectroscopy(XPS). The obtained $O_{1S}$ spectra of $Na^+-$, $Fe^{2+}-$ and $Fe^{3+}-$ exchanged zeolite X and Y were deconvoluted to demonstrate electronic binding energy of framework oxygens. There were 2-3 bands in each spectrum. The characteristics of separated band have been studied in terms of binding energy and relative area of $O_{1S}$ electron with respect to the exchanged cation. Those bands were assigned to the bridged oxygen in framework (band 1), cation bonded oxygen in cationic site (band 2) and oxygen in water coordinated to the cation (band 3) each other. The band 1 occupying the majority area of $O_{1S}$ spectrum was shifted to higher region on binding energy according to the decrease of Al content in zeolite.

• Journal of the Korean Chemical Society
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• v.29 no.6
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• pp.599-607
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• 1985

Near-ir spectra have been obtained for the $ν_3$+ Amide II combination thioacetamide(TA) band in CC$l_4$ and TA-DMP in CC$l_4$ in the range of 5 to 55${\circ}C$. Absorbance of the weak bands of the DMP and solvent has been compensated. The spectra are analyzed by the computer resolution into two Lorentzian-Gaussian product bands which have been identified with monomeric TA and 1 : 1 TA-DMP complex. Equilibrium constants and thermodynamic parameters for the hydrogen bonding between TA and DMP have been evaluated by the analysis of the concentration and temperature dependent spectra for the very dilute CC$l_4$ solutions. The $ΔH{\circ} and ΔS{\circ}$ of TA and DMT have been found to be -14.6 kJmo$l^{-1}$ and -16.2 Jmo$l^{-1}$ de$g^{-1}$.

• Journal of the Korean Chemical Society
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• v.39 no.11
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• pp.837-841
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• 1995

Thermodynamic parameters for the hydrogen bonding between thiopropionamide(TPA) and proton donors such as triethylphosphine oxide(TEPO), triphenylphosphine oxide(TPPO), trimethylphosphate(TMP), and tributyl phosphate(TBP) in dilute carbon tetrachloride solution have been measured by near-IR spectroscopy. The νa + amide Ⅱ combination band of TPA has been resolved into two Lorentzian-Gaussian product components which have been identified with monomeric TPA and 1 : 1 hydrogen bonded complex. The equilibrium constants and thermodynamic parameters for the formation of 1 : 1 hydrogen bonded complex have been obtained by the analysis of concentration and temperature dependent spectra. The standard enthalpies for the 1 : 1 hydrogen bonded complex formation of TPA with TEPO, TPPO, TMP, and TBP in CCl4 have been found to be - 21.4, - 16.8, - 12.8, and - 12.9 kJ/mol, respectively. The results are explained by the inductive and steric effects of substituents.