• Magazine of the Korea Concrete Institute
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• v.5 no.1
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• pp.115-127
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• 1993

본 연구의 목적은 프리캐스트 콘크리트(P.C) 대형판 아파트 구조물에 대한 우리나라 내진설계기준안 및 지침을 수립하기 위해 필요로 하는 정보를 취득하는데 있다. 이것은 실제 지진과 유사한 진동을 발생시키는 진동대를 사용하여 P.C대형판 구조물의 거동을 분석관찰함으로써 달성되었다. 여기에 사용된 시험체중의 하나는 습식접합 1/3 축소 3층 입체 P.C모델이었다. 지진파를 일으키기 위해 4mx4m 크기의 진동대가 사용되었다. 또한 선택한 입력지진가속도파는 Taft N21E 성분기록지진파로서 최대지진가속도(PGA)는 원하는 지진세기수준에 따라 조정되었고 시간축으로는 동적상사성법칙에 따라 축소되었다. 이 P.C모델의 진동대 실험을 통해 얻은 결과를 근거로 하여, 근거로 하여 다음과 같은 결론을 도출하였다. (1)이 시험체에 관한한, 지진안전계수는 7-8정도로 나타났으며, (2)이 P.C모델이 감쇠계수는 대체로, 철근콘크리트구조물 감쇠계수의 두배에 해당하는 값인 8%정도이며, (3) 이 모델은 접합부의 벌어짐과 미끄러짐에 의한 에너지소산을 통해서 2-3정도의 전체적인 변위연성비를 보여주었다.

• Journal of Korea Society of Industrial Information Systems
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• v.4 no.2
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• pp.32-38
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• 1999

In this study, an objection is to develop a electronic circuit of a gauage using radioisotope for compaction control to be needed at public works The developed gauage makes use of radioisotope with the activity exempted from domestic atomic law and consists of measuring circuits for gamma-rays and thermal neutrons, a high voltage supply unit and a microprocessor. To obtain meaningful numbers of pulse counts, parallel five and tow circuits are provided for gamma-rays and thermal neutrons, respectively. Also, to minimize effects of natural environmental radiation and electrical noise, circuits are electrostatically shielded and pulses made by ripples are eliminated by taking frequency of high voltage supplied to the circuit and pulse height of ripples into consideration One-chip microprocessor is applied to process various counts, results are stored, Enough and meaningful numbers of pulses are counted with the prototype gauage for compaction control.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.5
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• pp.1-11
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• 2006

The effects of continuous blowing on flow control and stall suppression for flows over a NACA 0015 airfoil at low Reynolds numbers were numerically investigated through its parameter variation on unstructured meshes. The aerodynamic force and moment variations due to flow control were examined, along with the stall angle-of-attack change for stall suppression. The results showed that blowing with relatively strong jet increases lift at the cost of drag increment below stall angle. Continuous blowing delays flow stall when it is implemented near the leading edge. When the blowing jet was aligned along the flow direction on the airfoil, the favorable flow control effect was most significant below the stall angle of attack.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.1
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• pp.101-109
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• 1999

The objective of this research is to study effects of the residual stresses on the crack growth and the life of the structure, caused by cold working around the hole of the aircraft structure which will be jointed by rivets and bolts, etc. The compensated Morrow's equation, by experimental data from the materials AL7075-T6 and AL2024-T3, is suggested to calculate the values of the fatigue life prediction of the structure. Also, the compensated Forman's equation, by experimental data from a material AL7075-T6, is suggested to calculate the values of the crack growth prediction of the structure. It is founded that the calculated values from the suggested equations are almost close to the known values of the fatigue life prediction and the crack growth prediction. It is shown that this paper, associated with an initial research on the effects of residual stresses around hole, gives a direction to study the problem at the aircraft maintenance field.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.6
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• pp.63-71
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• 1998

In this paper, we experiment the characteristics of coupling coefficient, gain, diffraction efficiency and dependence of time determined by TWM(Two-Wave Mixing), using Fe-LiNbO$_3$ crystal(doped with 0.015Wt.%). From these results, we proposed to apply for optical memory application. The highest coupling angle of 14。 and maximum coupling coefficient of 6.9$cm^{-1}$ / are obtained at 514.5nm wavelength. Also, maximum diffraction efficiency is 54.13% when intensity ratio and writing beam incident angle are 0.1 and 14o, respectively. After fixing process, diffraction efficiency is 21.4%. As an example, we demonstrated the writing and reconstruct optical data using spatial light modualtor and angular multiplexing in most optimal condition.

• Journal of the Korean Chemical Society
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• v.37 no.10
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• pp.861-866
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• 1993

In general, the concentration of constituents can be more accurately measured in x-ray fluorescence analysis of Fe-Ni-Cr alloy by reducing and correcting the matrix effect with standard ingot samples. Because of the difficult the treatment at a high temperature in preparing the ingot samples of various concentrations, several standard specimens were prepared by mixing the powders of the metallic oxides in certain proportions and pressing them with a costant pressure. With the metallic oxide specimens thus obtained, different matrix coefficients were calculate from the intensities of the strength of the x-ray fluorescence and the concentration of the substances. It is found that effects of Fe and Cr on Ni are absorption rich and effects of Fe and Ni on Cr are enhancement rich, whereas Ni enhances Fe Fluorescence but Cr absorves Fe K${\alpha}$ line. And the x-ray fluorescence intensities were compared and analyzed between the metallic oxides and the ingot samples.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.7
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• pp.1160-1164
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• 2008

This paper presents an wideband stripline balun. And, the proposed balun is composed of one power divider and two phase converters on stripline substrate. The target characteristics of the proposed balun is the combination loss of below -0.05 dB, an amplitude imbalance of ${\pm}0.5\;dB$ and a phase imbalance of $180{\pm}10$ degrees, with the reflection coefficient(S11) of below -10 dB over frequencies ranging from 500 to 1500 MHz. The fabricated balun occupies the area of $12(W){\times}220(L){\times}2.3(T)\;mm3$. Experimental measurement shows that the fabricated balun has an amplitude imbalance of ${\pm}0.7\;dB$, a phase imbalance of $180{\pm}8$ degrees and an insertion loss of about -2 dB with the reflection coefficient(S11) of below -10 dB over frequencies ranging from 500 to 1,500 MHz.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.21 no.1
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• pp.28-34
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• 1985

This paper describes that the characteristic of movement and the performance of the directional system of the liquid magnetic compass analyze and investigate in the kinds of compass and the coefficient of viscosity of the liquid of compass, which the horizontal magnetic field of the geo-magnetic is varied from the equator to the polar region (0.39 gauss-0.03 gauss) by use of apparatus generating artificial magnetic fields. The results are as follows; 1. It is confirmed that the measured values and the calculated values on the characteristic of damping curve by the type of compass and coefficient of viscosity has almost agree with one another. 2. As the horizontal magnetic force geo-magnetic field approaches around the equator (0.39 gauss), the horizontal magnetic field get near the polar region (0.03 gauss), its period is to be longer and the compass card prove not to be more stabilized. 3. The coefficient of viscosity of the liquid in the A, B, C, D and E compasses used in the experiment is estimated 0.03 poises, 0.02 poises, 0.02 poises, 0.015 poises and 0.048 poises respectively by computer simulation.

• Journal of the Korea Society of Computer and Information
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• v.15 no.10
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• pp.99-104
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• 2010

In this paper, the internal antenna for mobile communication handset which is able to control both coupling coefficient and resonant frequency without any major modification of radiator and ground plane of PIFA(Planner Inverted F Antenna). The resonant frequency as well as amount of coupling between feeding point and shorting post can be adjusted by changing inductance. Because the inductor is connected on shorting post where the strength of electric field is weak, the performance reduction of the proposed antenna is very small enough to neglect. For the variation of the inductance value within 3.3nH, the resonant frequency of antenna can have operating range of 1650MHz ~ 1830MHz. And as be increased the inductance, the coupling coefficient of antenna is over coupled. This means that it can be electrically controlled the resonant frequency and input impedance of antenna by inductance and minimized the mismatch loss. Size reduction of 10% for PIFA is obtained without any major modifications of antenna elements. For the frequency range from 1650 to 1830MHz, reduction of the measured antenna gain is within 0.93dB as varying the value of inductance from 0 to 3.3nH.

• Journal for History of Mathematics
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• v.26 no.2_3
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• pp.163-176
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• 2013

This study concerns Stanojevic's academic works on the $\mathfrak{L}^1$-convergence of Fourier series from 1973 to 2002. We review his academic works. Also, we briefly investigate a simple academic lineage for the researchers of $\mathfrak{L}^1$-convergence of Fourier series until 2012. First, we introduce the classical lineage of the researchers for $\mathfrak{L}^1$-convergence Fourier series in section 2. Second, we investigate the backgrounds of Stanojevic's study at Belgrade University and University of Missouri-Rolla respectively. Finally, we compare and consider the $\mathfrak{L}^1$-convergence theorems of Stanojevic's results from 1973 to 2002 successively. In addition, we compose a the simple lineage of $\mathfrak{L}^1$-convergence of Fourier series from 1973 to 2012.