• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.895-896
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• 2010

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.253-259
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• 2003

This paper presents the basic characteristics of a 5 element dipole array antenna which has a four parastic element and one driving element at the center of the circular array. The coupled integral equations for the unknown current distributions on dipole elements are derived and solved by applying Galerkin's method of moments. The numerical results show that the highest power gain of 7.8 dBi is obtained at radius of d = 0.3lλ when two short circuited parastic element neighbors. In order to verify the theoretical analysis, the radiation pattern is compared with Preston's results.

• Journal of The Korean Association For Science Education
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• v.27 no.5
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• pp.447-455
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• 2007

The Research works published in the field of Korean science education in relation to the theories of 'J. Piaget', 'D. P. Bruner' or 'J. S. Ausubel' have been analyzed and their general pattern of study were determined. Specifically, based on science education related articles published in several Korean journals, the pattern of research about the three scholars' theory is identified with the classification of the specific kind of journal, year of publication, key word, field of study, field of research, and grade of school. The journals subjected to the present study include 'Journal of the Korean Physical Society', 'Journal of the Korean Chemical Society', 'Journal of the Korean Biology Society', 'Journal of the Korean Earth Science Society', 'Journal of the Korean Association for Research in Science Education', and 'Journal of the Korean Society of Elementary Science Education'. It is determined from the present study as follows: First, the total number of related articles published in said journals is 97, and 'Journal of the Korean Association for Research in Science Education' ranks first in numbers. In terms of time period, it is found that most of the researches has been carried out during the mid 90s, and is still popular today. In addition, our key word search revealed that the 'cognitive development' by Piaget is most widely studied in the articles and biology is the area that has been most frequently studied. As to the field of research, teaching study was the one that has been most widely studied. Further, many articles have focused their studies on middle school. In conclusion, it is found that the Korean research works so far made for the theory of 'J. Piaget', 'D. P. Bruner' or 'J. S. Ausubel' are rather limited to a certain area and field, etc.

• Journal of the Korea Society of Computer and Information
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• v.5 no.2
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• pp.115-120
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• 2000

This papers describes two low-noise amplifiers that use the Hewlett-Packard ATF-10236 low noise GaAs FET device, The actual measured performance of the amplifiers compares favorably to that predicted by the computer simulation(ADS) the noise figure of the 1575MHz amplifier was measured at 1.78dB which is lower that 2dB as specified. Measurement gam measured 33.0075dB which is within 35dB$\pm$0.5㏈ of the GPS specification. Network Analyzer(HP8510) is used to measure all the s-parameters and Noise Figure meter(HP8970B) is used to measure noise figure. As the result of experiment, gain, input VSWR, output VSWR is within the GPS specification sufficiently.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.325-326
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• 2007

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.1
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• pp.44-52
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• 2016

Kelvin's (1887) theory that predicts position of ship wave crest can be applied only in deep water. Havelock's (1907) theory that predicts cusp locus angle can be applied in whole water depths but cannot predict the position of ship wave crest. In this study, using the linear dispersion fully, we develop the equations to predict ship wave crest in whole water depths and, using the developed equations, we predict cusp locus angle. We simulate ship wave propagation using FLOW-3D in the condition of Johnson's (1985) hydraulic experiment and find that the cusp locus angles predicted by the present theory are close to numerical results of FLOW-3D and hydraulic experimental data. We also simulate for various conditions and compare numerical results of distances between adjacent wave crests and values predicted by the present theory. For Froude number less than unity, the numerical results are close to the values predicted by the theory. For Froude number greater than unity, the constant value of $C_1$ which determines the distance between the ship and the first ship wave crest is almost equal to zero and the numerical results of distances between adjacent ship waves excluding the first ship are close to the values predicted by the theory.

• The Journal of the Acoustical Society of Korea
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• v.31 no.1
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• pp.11-18
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• 2012

In this paper, the occurrence of a stopband phenomenon when an acoustic wave propagates through periodically corrugated ducts is discussed using theoretical and BEM analyses. A 2-D duct with sinusoidally corrugated upper and lower walls is considered. When the magnitude of the sinusoidal corrugation is sufficiently small compared to the duct's height, the wave equation is solved with the multiple scaling perturbation method. Then stopbands for Bragg and non-Bragg resonances are computed from the condition where frequency becomes a complex number. A 2-D BEM analysis is performed to compute insertion loss of the duct, and stopbands are confirmed as predicted by analytical analysis.

• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.787-801
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• 2006

Focused in the characteristic of R&D on Geoscience and Mineral Resources as basic research area, we survey on methods of public works' economic impact analysis including cost-benefit analysis and resent technology evaluation methods and suggest apply-methods to conduct economic impact analysis on R&D of geoscience and mineral resources. To conduct economic impact analysis on the basic research area, it need to identification research's out-come not just output. In this perspective, we propose a method, Input-Output-Outcome Roadmapping to identify the outcome of R&D and show the relation of input, output, and outcome of R&D. Furthermore, noticing the different effects of R&D from public works, we directly evaluate the use-value of the academic theory or geological maps through Contingent Valuation Method(CVM) and others developed as evaluation methods on environmental goods. In indirect application methods, it can evaluate the partial of the pubic works' benefit with assuming R&D factors if R&D is a part of public works. If not, we evaluate the R&D's value as reductions of costs or additions of benefit with finding related public works.

• Nuclear Engineering and Technology
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• v.3 no.1
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• pp.21-31
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• 1971

The part of the work of plastic deformation of metal goes into the changes in the total surface free energy. This contribution is dependent on the specific surface free energy, which is affected by the environment. Based on thermodynamical approach, volume constancy requirement and adsorption induced two distinct dislocation interaction mechanisms for strengthening or weakening of metals at surface, theoretical derivation has been made to show that the environmental contribution on the strain hardening, the stress and the energy required for plastic deformation can be expressed in terms of solid surface tension in vacuum (${\gamma}$$_{s}$), interfacial tension (${\gamma}$$_{se}$ ), surface dislocation density ($\rho$$_{s}$), internal dislocation density ($\rho$$_{i}$) and fraction of surface site uncoverage (f). On the basis of theoretical derivation, the various mechanical behaviours under different environments are predicted.d.d.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1447-1454
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• 2013

In this study, we developed the equation of ship wave crests in intermediate as well as deep waters by extending Kelvin's (1887) theory using the recursive relation for the dispersion relation. The present equation can be applied for varying water depth as well as constant water depth. Using FLOW-3D we conducted numerical experiments to verify analytical prediction. The ship wave crest patterns became asymmetric on a plane slope when the ship propagates alongshore direction. That is, in shallower side, wave crests tend to be parallel to the coastline due to refraction and, in deeper side, wave crests tend to be orthogonal due to reverse refraction.