• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.85-98
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• 1993

A method of analysis for the material and geometric nonlinear analysis of planar prestressed concrete cable-stayed bridges including the time-dependent effects due to load history, creep, shrinkage, aging of concrete and relaxation of prestress is described. The analysis procedure, based on the finite element method, is capable of predicting the response of these structures through elastic, cracking, inelastic and ultimate ranges. The nonlinear formulation for the description of motion is based on the updated Lagrangian approach. To account for the material nonlinearity, nonlinear stress-strain relationship and cracking of concrete, nonlinear stress-strain relationships of reinforcing steel, prestressing steel, and cable, including load reversal are given. Results from a numerical examples on ultimate analyses of cable-stayed bridges are presented to illustrate the analysis method.

• Korean Journal of Materials Research
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• v.8 no.6
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• pp.477-483
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• 1998

$SiC_{4}$$C_{3}$$H_{ 8}$$H_{2}$와 $C_{3}$$H_{8}$ $H_{2}$, $CH_{3}$$SiCI_{3}$$CH_{4}$$H_{2}$계를 사용하여 흑연기판 위에 SiC와 SiC/C FGM을 CVD법에 의해 코팅하였다. $SiCI_{4}$$C_{3}$$H_{8}$ $H_{2}$ 계에서 SiC 증착 시 바람직한 수소의 비는 10-30사이였고 결정 배향성은 입력가스의 탄소비에 따라 여러번의 대 반전이 일어났다. 성장조건을 {111} 배향성을 갖도록 조절하는 것이 FGM층간 접착상태를 증진시킬 수 있는 방법으로 판단되었다. $CH_{3}$$SiCI_{3}$C$_{3}$$H_{8}$ $H_{2}$ 계에서는 SiC와 C의 비율을 조절하기가 $SiCI_{4}$$C_{3}$$H_{8} $H_{2}$계를 사용했을 때 보다 용이하였고, FGM 단면 관찰에서 층간의 뚜렷한 경계를 발견할 수 없을 정도로 우수한 층간 접착상태를 보였다.

• Korean Journal of Optics and Photonics
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• v.14 no.5
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• pp.483-490
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• 2003

We have analyzed theoretically optical pulse propagation in a coherent atomic medium for amplification without inversion (AWI), which is achieved by adding incoherent optical pumping to a typical EIT system. In order to explain experimental results [Kim et al., J. Phys. B, 36, 2671(2003)] to control the group velocity of the optical pulse by changing pumping power, we established a 5-level atomic system and applied density matrix equations. This AWI model system is different from previous AWI systems from the viewpoint of using two levels for incoherent optical pumping isolated optically from the EIT (electromagentically induced transparency) system so that more atoms can participate in pulse speed control. We have found that population transfer by collisions between ground states plays a decisive role for efficient AWI, and more atoms are effective for slowing the pulse. Our numerical results are in good agreement qualitatively with experimental results.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.9 s.339
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• pp.9-18
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• 2005

To make high-performance, low-power transistors beyond the technology node of 60 nm complementary metal-oxide-semiconductor field-effect transistors(C-MOSFETs) possible, the effect of electron mobility of the thickness of strained Si grown on a relaxed SiGe/SiO2/Si was investigated from the viewpoint of mobility enhancement via two approaches. First the parameters for the inter-valley phonon scattering model were optimized. Second, theoretical calculation of the electronic states of the two-fold and four-fold valleys in the strained Si inversion layer were performed, including such characteristics as the energy band diagrams, electron populations, electron concentrations, phonon scattering rate, and phonon-limited electron mobility. The electron mobility in an silicon germanium on insulator(SGOI) n-MOSFET was observed to be about 1.5 to 1.7 times higher than that of a conventional silicon on insulator(SOI) n-MOSFET over the whole range of Si thickness in the SOI structure. This trend was good consistent with our experimental results. In Particular, it was observed that when the strained Si thickness was decreased below 10 nm, the phonon-limited electron mobility in an SGOI n-MOSFT with a Si channel thickness of less than 6 nm differed significantly from that of the conventional SOI n-MOSFET. It can be attributed this difference that some electrons in the strained SGOI n-MOSFET inversion layer tunnelled into the SiGe layer, whereas carrier confinement occurred in the conventional SOI n-MOSFET. In addition, we confirmed that in the Si thickness range of from 10 nm to 3 nm the Phonon-limited electron mobility in an SGOI n-MOSFET was governed by the inter-valley Phonon scattering rate. This result indicates that a fully depleted C-MOSFET with a channel length of less than 15 m should be fabricated on an strained Si SGOI structure in order to obtain a higher drain current.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.155-162
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• 2012

When RC (Reinforced Concrete) structures are exposed to sea water, steel corrosion can occur and this leads a degradation of structural performance. Referring the electro-deposition system with sea water from the 1st step research, durability and structural performance are evaluated in coated steel and RC members containing it in the 2nd research. In the durability performance test, Half Cell Potential test is performed and the coated steel is evaluated to have the high resistance to corrosion, which shows only 35% of corrosion velocity in normal (bare) steel. In the structural performance test, tensile strength, adhesive strength, and flexural/shear in RC member are performed. For the electro-deposit coated steel, increasing ratios of 3.2% and 8.8% are evaluated in the test of tensile strength and adhesive strength, respectively. For the structural test in RC member, there is no big difference between RC members with coated and non-coated steel in ultimate load and failure pattern It is evaluated that the chemical compound with $CaCO_3$ and $Mg(OH)_2$ from electro-deposition causes slightly increased structural performance. The electro-deposit coated steel can be more widely applied after performance verification from several tests like fatigue, resistance to impact, and long term-submerging test.

• The Journal of the Korea Contents Association
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• v.19 no.8
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• pp.359-369
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• 2019

This research suggests video solutions and efficient implementations for low-budget performances. This study adopts Millumin as a mapping server, which reflects the character of small theatres with a lower budget that doesn't use more than four projectors in a show. By comparing pros and cons of media servers, the study discovers how to employ an appropriate server as well as to participate in a pre-video production stage, which increases the artistry of directing and reduces unnecessary graphics. Meanwhile, with the participation of an interpretive programmer, this study suggests a way to manage the rehearsal time and to increase the artistry of directing. In addition, this study analyses the relationship between the video's visual motive source in the story's development, crisis, climax, twist and the provided narrative based on "Trace U the musical (2018)", by this analyzation, the relationship between storytelling and the video is fully shown. A visual motive is related to the action of actors, the movement of dancers, the music, the lyrics and the lines. Furthermore, the provided narrative confirms that the existence of an actual relationship with the turning point of the plots, characters' emotion, suggestions of sub-plot and the twists of own story. In conclusion, it implies a video of small theatres can not be separated from the probability of the narrative.sh an efficient ad execution strategy that reflected the characteristics of mobile devices.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.9
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• pp.785-795
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• 1990

For the far field radiation pattern of a microstrip array antenna which is conformed to a cylindrical surface and forms an arc array, an approximate analysis method using FOURIER TRANSFORM is presented. In this method, the conformal array antenna is projected on the effective aperture plane and assumed to be an aperiodic array with nonlinear phase tilt. The effective aperture plane includes four end-points of each arc on the cylindrical surface. When the effective aperture ratio which is normalized to the planar type is from 1.0 to 0.9, it is confirmed that this approximate method is valid. To the array on the effective aperture plane, it is assumed that the phase tilt is due to the distance between aperture plne and curvature surface. Specially, when the radius of arc is more than 5 times to its length, the FOURIER TRANSFORM METHOD could be used with only varying scale factors. The results of calculating by approximate method are good agreement with the results of COORDINATE TRANSFORM METHOD and experimentally measured value in the range of -40dB. And, the difference of half power angle is less than 5 degrees when the effective aperture ratio moer than 0.9.

• Journal of Korea Society of Industrial Information Systems
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• v.21 no.5
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• pp.73-83
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• 2016

NAVER provides search frequency data of search terms via its DataLab service (http://datalab.naver.com/). Using this data, this paper examines the relation between the search frequency of firm's name and its future stock returns. Our results show that the search frequency of firm's name is a new investor attention measure, which is different from previously explored attention measures such as extreme returns, turnover, etc. Firms that go through higher search frequency this week tend to have higher returns in the next week. We do not find return reversal in the long run for the firms with higher search frequency. Furthermore, the extent to which search frequency affects stock returns becomes more pronounced following market-wide attention grabbing events. Our results indicate that search frequency incorporates information for future stock returns.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.923-927
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• 2008

본 연구에서는 여주 등 6개 지점에서 유사의 이동이 활발한 시기인 $6{\sim}9$월에 부유사를 측정하여 하천의 유사량 특성을 파악하였다. 측선 배치는 유사채취의 난이도와 채취시간, 하도의 규모 등을 고려하여 등간격의 5개측선수를 적용하였다. 시료분석은 여과법, BW관법, 체분석법으로 수행하여 유사량 산정을 위한 기초자료로 이용하였고, 또한 부유사와 하상토 입경분포 분석 결과로 $Od{\acute{e}}n$ 곡선와 입경가적곡선을 작성하여 대상 지점의 유사특성을 파악하였다. 유량에 따른 총유사량의 관계를 도출하기 위해서 실측된 부유사와 수리량 자료를 이용하였으며, 유사의 거동을 이론적으로 모형화한 간접법으로 총유사량을 추정하였다. 국내 하천의 특성에 적합한 총유사량 추정방법이 아직까지 개발되지 않고 이에 따른 연구 또한 미진한 관계로 기존의 총유사량 산정공식들 중 국내에서 비교적 널리 적용되고 있는 Modified Einstein 공식을 선정하여 대상 지점에 적용하였다. 본 연구에서 선정한 Modified Einstein 공식으로 추정된 총유사량의 적정성을 검토하기 위한 부가적인 수단으로 Engelund&Hansen(1967년), Yang(1973년, 1979년), Ackers&White(1973년) 공식들을 선정하여 Modified Einstein 공식의 추정치와 그 특성을 비교 분석하였다. 그 결과, 일반적으로 모든 지점에서 Modified Einstein 방법으로 추정된 총유사량이 유량에 따라 변동이 크고 상관성이 낮게 분석되었으며, 그 외 3가지 방법으로 추정된 결과는 다소의 변동폭을 가졌으나 대체로 유량의 증가에 따라 유사량도 증가하는 일정한 경향을 나타내었다. 본 연구에서는 각 지점별 유사 유출량과 비유사량을 산정하기 위해서 유량-부유사량관계곡선식과 유량 수문곡선을 이용하였다. 그 결과, 임진강 수계에 위치한 적성 지점에서 가장 크게 산정되었으며, 구례2 지점에서 가장 적은 값을 가졌다. 6개 지점 중 서로 상 하류 관계를 가지는 낙동과 왜관 지점에서 유사량의 특성 변화를 검토한 결과, 상 하류 간의 반전은 저수위 구간을 제외하고는 발생하지 않았으며, 왜관이 낙동 지점보다 큰 값의 유사 유출량을 나타내었다.

• Journal of the Korean Magnetics Society
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• v.11 no.2
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• pp.63-71
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• 2001

The effects of an Ag seed layer on the magnetic properties and the microstructural evolution of SmCo/Cr thin films deposited on glass substrates were investigated. Coercivity of the films is 2.0 kOe when the thickness of Ag seed layer was 1nm thick, but it increased to 2.7 kOe when the Ag seed layer thickness is 3 nm. The increase of coercivity for film with 3 nm-thick Ag is due to roughness of Cr and grain size of Cr by the Ag microbumps. Ar partial pressure influenced on the formation of Ag microbumps, for example, they were formed at 5 mTorr when Ag thickness was 1 nm. The mechanism of magnetization reversal of the SmCo films changed from domain wall motion to domain rotation as the Ag inserted. This was thought to be due to inhibition of domain wall motion by the reduction of Cr grain size and the increase of roughness.