• Structural Engineering and Mechanics
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• 제90권4호
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• pp.391-401
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• 2024

The present study focuses on the effect of extension-bending coupling on the elastic stability (buckling) of laminated composite plates. These plates will be loaded under uni-axial or bi-axial in-plane mechanical loads, especially in the orthotropic or anti-symmetric cross-angle cases. The main objective is to find a limit where we can approximate the elastic stability behavior of angularly crossed anti-symmetric plates by the simple behavior of specially orthotropic plates. The contribution of my present study is to predict the explicit effect of extension-flexion coupling on the elastic stability of this type of panel. Critically, a parametric study is carried out, involving the search for the critical buckling load as a function of deformation mode, aspect ratio, plate anisotropy ratio and finally the study of the effect of lamination angle and number of layers on the contribution of extension-flexure coupling in terms of plate buckling stability. We use first-order shear deformation theory (FSDT) with a correction factor of 5/6. Simply supported conditions along the four boundaries are adopted where we can develop closed-form analytical solutions obtained by a Navier development.

• 한국과학교육학회지
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• 제2권1호
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• pp.16-30
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• 1980

In is a recent trend of the world to study the integrated science curriculum development. This study aims at pursuing how to integrate physics and earthscience in high school course and forming a tentative plan as to an integrated process between both the subjects. The one was compared with the other accor ding to the basic concepts and theteaching objecties. The contents of these two subjects were analysed, the overlapping parts being chosen, and so in the hierachy of the curriculum, some mistakes were found in eaching these two two subjects. It proved valid to in tegrate these two subject. A concrete scheme was offered to in tegrate these two subjects-physics and earthscience, when a tentative plan concerning, the integra ted process was made. This new plan can make the time required for teaching decrease by 5% The better study on the basic structure of the integrated concepts between these two subjects will go on further in this respect. It is necessary to train again the teachres concerned with this new subject and to put an emphasis on the elective course between physics and earthscience in the teacher's college curriculum.

• 천문학회지
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• 제39권2호
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• pp.51-56
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• 2006

We report the development of a semi-VLBI observation system operating at 21 cm and present the measurement of visibility function toward the sun using this system. The system consists of two 2.3 meter antennas with a maximum separation of 35 meter, a conventional high speed data acquisition system, and a set of programs for software correlation. Since two local oscillators of receiver modules are independent, data had to be fringe-fitted to yield the visibility amplitude. It is found that the visibility amplitude decreases and then bounces back as baseline increases. We confirm that solar disk with brighter limb best explains the measured visibility amplitude.

• Nuclear Engineering and Technology
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• 제56권7호
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• pp.2557-2562
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• 2024

A type of integrated multiple-single-channel analyzer (IMSCA) is described. The IMSCA works with an input pulse of 2-20 pC, and it can be directly connected to a scintillation detector, which eliminates the need for a linear amplifier. It consists of 64 input ports, so 1-64 detectors can be set by users according to different requirements. Two energy regions for each input channel can be simultaneously analyzed. Another advantage of the IMSCA is that it integrates with a high-speed pulse signal acquisition card and transmits data to the computer through the network. The maximum pulse through-rate is 1.4 MHz, and linearity can reach 0.1%. This IMSCA has been successfully used in enrichment detecting of nuclear fuel rod.

• Current Applied Physics
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• 제18권12호
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• pp.1473-1479
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• 2018

Recently multiferroic materials have attract great interest for the applications on memorial, spintronic and magneto-electric sensor devices for their spontaneous magneto-electric coupling properties. Research and development of the various kinds of multiferroics are indispensable factor for a new generation multifunctional materials. In this research, mechanical, electronic, magnetic and nonlinear optical properties of La modified $BiLaFe_2O_6$ (BLFO) and Mn modified $Bi_2FeMnO_6$ (BFMO) were studied as new members of multiferroic $BiFeO_3$ (BFO) series by first-principles calculations, and compared with the pure BFO to discover the optimized properties. Our results show that BLFO and BFMO have good mechanical stability as revealed by elastic constants that satisfy the stability criteria. All these compounds exhibit anisotropic and ductile nature. The enhanced properties by La and Mn substitution, such as increased hardness, improved magnetism, decreased band gap and comparable second harmonic generation responses reveal that the new multiferroic members of BLFO and BFMO would get wider application than their BFO counterpart. Our study is expected to providing an appropriate mechanical reference data as guidance for engineering of high efficiency multifunctional devices with the BFO series.

• Journal of the Optical Society of Korea
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• 제18권6호
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• pp.809-817
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• 2014

The loss in contrast-discrimination ability of the human visual system under high ambient illumination level can cause image quality degradation in mobile phones. In this paper, we propose a perceived contrast compensation method by processing the original displayed image. With consideration that the perceived contrast significantly varies across the image, this method extracts the local band contrast from the original image; it then compensates these contrast components to counteract the perceived contrast degradation. Experimental results demonstrate that this method can maintain most contrast details even in high ambient illumination levels.

• Journal of the Optical Society of Korea
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• 제14권4호
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• pp.420-423
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• 2010

We fabricated 1 mm-thick periodically-poled lithium niobate (PPLN) crystals by using a high-voltage amplifier for standard electric field poling combined with a voltage multiplier. Furthermore, two 1 mm-thick PPLNs were directly bonded to make a 2 mm-thick PPLN. The large aperture allowed broad angular tuning, and a broad spectral range of quasi-phase matched second-harmonic generation can be achieved in a single channel. High-power applications are also expected.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.249.1-249.1
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• 2008

• 영재교육연구
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• 제3_4권1호
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• pp.139-147
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• 1994

The "First Step to Nobel Prize in Physics" is an annual competition in research projects in physics for secondary (high) school pupils organized by the Institute od Physics, Polish Academy of Sciences. This year the second competition of that type has been completed. Pupils from 36 countries took part in the first two competitions, what certainly should be treated as a great success. We have organized the above competition for the following reasons. During our contacts with secondary school pupils we discovered that some of them try to perform different physical investigations by themselves: at schools, in some laboratories and even at home. Then we decided to organize the National Competition in Pupils' Research Projects in Physics and next - after gaining some experience in the national scale - the international competition "First Step to Nobel Prize in Physics". Our aim was to recognize the effort of the pupils, give them a chance to compare their own achievements with the achievements of their colleagues and organize their work. One should underline that the "First Step" refers to quite different features (long term research work) of the pupils than the International Physics Olympiad (solving well formulated physics problems). The prizes in our competition are not typical. Instead of buying some items for our winners we decided to invite them to our Institute for a research stay. In our opinion in case of people whose hobby is physics such a form of prize is more valuable and more instructive than anything else. The aim of this article is to discuss a genesis of the competition, to present conditions of participation and to discuss the results.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 1999년도 Japanese Journal of Medical Physics
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• pp.320-322
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• 1999