• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.600-606
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• 2007

3D finite element analyses of a corrugated steel web girder and a steel truss web girder are conducted to investigate the static and dynamic behaviour of the hybrid girders. And the analyses results are compared with those by the equivalent beam theory. The equivalent theory is a theory that all section properties of a truss structure are replaced by section properties of a beam including a shear coefficient. When applying the equivalent beam theory, the shear coefficient of the corrugated steel web girder is estimated as the area ratio of flange section to web section and that of the steel truss web girder is calculated by the equation proposed by Abdel. Static deflections and natural frequencies by 3D finite element analyses and those by the equivalent beam theory are in good agreement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.567-574
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• 2003

It is important to design and evaluate the chip waveform with the minimum MAI under the bandwidth constraint in the interference-limited DS-CDMA system. In this paper, by approximation we present the analytical chip waveforms that are proposed and optimized in the reference. Their performances are compared with performances of three conventional chip waveforms: rectangular, half-sine and raised-cosine. Waveform 1 of the proposed chip waveform outperforms the conventional ones. BER and throughput performance are evaluated in the Rayleigh and Nakagami-m fading channels when DPSK modulation is used. When the required BER is 10$\^$-3/ in two fading channels, the capacity of the waveform 1 is improved about 20 % rather than raised-cosine one. When the offered traffic is 30 and the number of packet per bit(N$\sub$d/) is 14, maximum throughput of the waveform 1 is better than raised-cosine chip waveform about 18 % in two fading channels.

• 전기의세계
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• v.18 no.4
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• pp.16-21
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• 1969

3상유도전동기에 정현파형의 불평형 3상전압 혹은 고주파성분을 포함한 동일파형의 3상전압을 인가했을때의 전동기의 특성에 대ㅏㄴ 것은 발표되어 있지만, 고주파성분을 포함하고, 동시에 동일파형이 아닌 3상전압을 인가했을때의 특성에 대한것은 별로없는 것 같다. 수전단에서는 이러한 전압이 실제 인가되므로, 본논문은 고주파성분을 포함한 동일파형이 아닌 3상전압을 중성점이 접지되어 있지않은 3상유도전동기에 인가할때의 전동기의 특성을 몇가지 가정하에 작성한 등가회로에 의하여 수식적으로 해석하고 이를 실험에 의하여 확인하였다.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.811-812
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• 2006

본 논문은 부하상태에 따른 매입형 영구자석 전동기에서의 역기전력 파형을 제시하였다. 유한요소해석에 기초한 고정투자율법을 사용하여 무부하 상태뿐만 아니라 부하상태에 따른 역기전력 파형을 해석하였고, 매입형 영구자석 전동기의 설계변수가 역기전력 파형의 고조파 성분에 미치는 영향을 조사하였다.

• Tribology and Lubricants
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• v.6 no.1
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• pp.89-98
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• 1990

시일의 접촉면이 경사지고, 정현파형이 존재하며 코닝이 있는 경우에 대한 해석을 하였다. 또한 시일링 간극에 존재하는 유체는 비압축성 점성유체이다. 이러한 요소들을 고려한 레이놀즈 방정식의 일반해를 구하기 위하여 멱급수 근사이론을 이용하여 압력분포를 구하였고, 이 결과를 이용하여 시일의 누설 유동량 및 마찰 토오크를 해석하였다. 계산 결과에 의하면 시일 접촉면의 표면파형이나 코닝에 비하여 경사정도가 시일의 성능에 커다란 영향을 주고 있음을 보여주고 있다.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.83-83
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• 2022

여러 분야의 연구자들이 지진해일의 위험에 대한 경각심을 가지고, 지진해일의 발생, 전파 그리고 수리현상을 해석하기 위해 많은 노력을 기울이고 있다. 해안지역에서 직접적인 피해를 입히는 지진해일의 충격파, 처오름, 월파, 침수 등에 관한 연구에 유사한 파형 특성을 가진 고립파를 많이 사용한다. 고립파는 비선형성과 분산이 균형을 이루는 가정에서 Korteweg-de Vries(KdV) 방정식을 만족하는 안정적인 이론파이다. 고립파의 파형분포는 수심에 의해 결정되고, 일정 수심 이상에서는 지진해일을 대신해 사용할 수 있다. 그러나 수심이 낮은 천해에서는 주기와 파장이 비현실적으로 짧아짐으로 지진해일을 대신하기에는 무리가 있다. 본 연구에서는 지진해일의 처오름 특성을 분석하기 위한 1:20 불투과성 경사면이 포함된 수치파동수조를 구성한다. 먼저, 일본 NOWPHAS(Nationwide Ocean Wave information network for Ports and HArbourS)의 관측자료를 이용하여 2011 동일본 지진해일과 고립파의 파형분포를 비교한다. 그리고 다양한 파형의 지진해일 생성할 수 있게 개발된 조파방법을 수치파동수조에 도입하여 수치해석을 수행한다. 수치해석결과, 지진해일의 처오름 높이가 고립파에 비해 최대 1.8배, 최소 1.13배, 평균 1.56배 증가한다.

• Journal of Korean Society of Steel Construction
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• v.19 no.5
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• pp.463-472
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• 2007

This paper presents theoretical and finite element analysis results for the lateral-torsional buckling of I-girders with corrugated web under uniform bending. Lateral-torsional buckling is a major design aspect for flexural members composed of thin-walled I-section. However, torsional rigidities such as the warping constants of the I-girders with corrugated web are not fully understood yet. In this paper, bending and pure torsional rigidities of I-girders with corrugated web are first described using the results of previous researchers. Then, the location of the shear center and the warping constants are derived. Using the derived section properties of I-girders with corrugated web, the lateral-torsional buckling strength is determined. Finite element analyses are conducted and the proposed lateral-torsional buckling strength of I-girders with corrugated web is successfully verified. Finally, the effects of corrugation profiles of the web on the lateral-torsional buckling load of I-girders with corrugated web are discussed.

• Journal of Korean Society of Steel Construction
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• v.27 no.5
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• pp.455-470
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• 2015

This research suggest method to calculate more accurate shearing and bending force on corrugated steel plate that it is produced domestically. This research analyze limitation of former formula on domestic design standard and existing research. In addition The strength calculation formula on corrugated steel plate was proposed according to result of the experiment and FEM analysis. In this study, the result that compare experiment with analysis using the proposed shear buckling coefficient and limit width to thickness ratio indicate similar behavior. As the result of the research, It is judged that the structural member design and performance evaluation of the corrugated steel plate was conveniently applied.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6A
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• pp.347-354
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• 2012

In this study, the equations of torsional and warping constants of a I-shaped plate girder with sine corrugated web are suggested. Because of geometric characteristics of the section, a I-shaped plate girder with corrugated web shows high out-of-plane stiffness, shear strength, and torsional stiffness. Torsional constant and warping constant definitely affect lateral-torsional buckling loads. Therefore, exact estimation of the sectional properties is quite important. But, it is difficult to estimate these properties by former methods. So, this study was focused on suggestion of the rational equations to calculate torsional and warping constants. In order to investigate the effects of geometric characteristics of sine-corrugated webs on torsional stiffness and warping torsional constant, finite element analyses for pure torsional behavior and warping torsional behavior of I-shaped plate girders were performed. By regression analyses of the analytical results, rational equations of the torsional constant and warping constant were suggested. Suggested equations for the properties were validated based on the analytical results of lateral-torsional buckling of simply supported I-shaped plate girder. By suggested equations, torsional and warping constants of I-shaped plate girders with a sine-corrugated web can be rationally estimated and more exact lateral-torsional buckling load can be simply calculated.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.213-216
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• 2008

Sled test id widely used to evaluate the performance of occupant's safety system in frontal crash environment without having to conduct a full-scale crash test. Steel bar breaking system is used to generate deceleration profile which is experienced by passengers in frontal crash. In this study, deformation analyses of steel bars were conducted using a commercial FE code. Several guidelines were proposed to improve the accuracy of simulation.