• Structural Engineering and Mechanics
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• 제14권6호
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• pp.733-738
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• 2002

A simplified rational method is developed to evaluate transverse earthquake-induced forces in continuous bridges. This method models the bridge as a beam on elastic foundation, and assumes a sinusoidal curve for both vibration mode shape and deflected shape in the transverse direction. The principle of minimum total potential is used to calculate the displacements and the earthquake-induced forces in the transverse direction. This method is concise and easy to apply, and hence, offers an attractive alternative to a lengthy and time consuming three dimensional modeling of the bridge as given by AASHTO under its Single Mode Spectral Analysis Method.

• 한국소음진동공학회논문집
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• 제14권12호
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• pp.1314-1321
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• 2004

The non-linear responses of a slender rectangular cantilever beam subjected to lateral harmonic base-excitation are investigated by the 2-channel FFT analyzer. Both linear and nonlinear behaviors of the cantilever beam are compared with each other. Bending mode, torsional mode, and transverse mode are coupled in such a way that the energy transfer between them are observed. Especially, superharmonic, subharmonic, and chaotic motions which result from the unstable inertia terms in the transverse mode are analyzed by the FFT analyzer The aim is to give the explanations of the route to chaos, i.e., harmonic motion \longrightarrow superharmonic motion \longrightarrow subharmonic motion \longrightarrow chaos.

• 대한전자공학회논문지SD
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• 제42권12호
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• pp.19-26
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• 2005

모드별 광출력-전류-전압 특성, RIN (relative intensity noise) 스펙트럼, 계단 전류입력에 대한 과도응답의 측정을 통하여 다중 횡모드 VCSEL의 모드 거동과 동특성 사이의 관계에 대하여 살펴보았다. RIN 스펙트럼의 공진 주파수는 모드별 광출력 특성 곡선으로 잘 설명할 수 있었다. 그리고, 활성영역이 넓은 VCSEL은 각각의 횡모드가 문턱전류가 서로 다른 독립적인 레이저로 동작하여 turn-on 지연시간이 달라 다단계 turn-on 특성을 보인다. 고차 모드가 발진하면서 이렇게 펄스의 파형이 찌그러지고 상승시간이 급격히 증가하기 때문에 단일 모드로 동작하도록 전류입력을 조절하지 않으면 고속 광통신용 광원으로서는 적합하지 않게 된다.

• ETRI Journal
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• 제32권2호
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• pp.339-341
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• 2010

The fundamental transverse mode lasing of a hybrid laser diode is a prerequisite for efficient coupling to a single-mode silicon waveguide, which is necessary for a wavelength-division multiplexing silicon interconnection. We investigate the lasing mode profile for a hybrid laser diode consisting of silicon slab and InP/InGaAsP deep ridge waveguides. When the thickness of the top silicon is 220 nm, the fundamental transverse mode is lasing in spite of the wide waveguide width of $3.7{\mu}m$. The threshold current is 40 mA, and the maximum output power is 5 mW under CW current operation. In the case of a thick top silicon layer (1 ${\mu}m$), the higher modes are lasing. There is no significant difference in the thermal resistance of the two devices.

• International Journal of Railway
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• 제5권2호
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• pp.71-76
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• 2012

Recently, axle load, operating speed and traffic density on railroads have had a tendency to increase and thereby cause additional pressure applied on used track. These operating conditions frequently result in service failure due to wear caused by wheel-rail contact and fatigue damage under cyclic loading. Among rail defects, the transverse crack, which has been the most dangerous type of fatigue damages, is developed from the subsurface crack near the rail running face and grows perpendicular to the rail surface. Therefore, it is necessary to investigate systematically the growth behavior of transverse crack for rail steel under mixed mode. In this study, the fatigue crack growth behavior of the transverse crack in rail steel was experimentally investigated under mixed-mode variable amplitude loadings.

• 동력기계공학회지
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• 제4권4호
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• pp.70-77
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• 2000

On the dynamic behavior of a simple beam the influences of the velocities and distance of two moving masses have been studied by numerical method. The instant amplitude of a simple beam is calculated and analyzed for each position of the moving masses represented by the time functions. As increasing the velocties of two moving masses on the simple beam, the amplitude of the transverse vibration of the simple beam is decreased and the frequency of the transverse vibration of the simple beam is increased. As the distance between two moving masses increase, the transverse displacement of the simple beam is decrease. The simple beam is very stable in second mode at $\bar{a}=0.5$ and in third mode at $\bar{a}=0.3$.

• 비파괴검사학회지
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• 제16권4호
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• pp.234-240
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• 1997

기존의 Scanning Laser Acoustic Microscope (SLAM)에 횡파를 사용함으로써 분해능을 개선시키는 방법을 연구하였다. 액체-고체 경계에서는 모드 변환이 발생하여 액체에서 입사되는 종파 에너지의 일부분은 고체 시험편 내에서 횡파 에너지로 변환된다. SLAM의 분해능은 수신측의 레이저 빔 폭과 입사되는 초음파의 파장에 의하여 결정되고, 고체에서 횡파의 파장은 같은 주파수의 종파의 파장보다 짧기 때문에 횡파를 사용한다면 높은 분해능을 얻을 수 있다. 종파와 횡파를 사용하였을 때에 얻어지는 SLAM 영상을 시뮬레이션을 통하여 비교하여 횡파를 이용하면 분해능이 향상됨을 입증하였다. SLAM을 횡파 모드에서 동작시키기 위하여 입사각을 조절할 수 있는 ??지를 제작하였고, 알루미늄 시험편에 대하여 실험한 결과로부터 종파 모드 SLAM에 의한 영상보다는 횡파 모드 SLAM의 영상의 콘트라스트가 양호함을 확인하였다.

• 한국연소학회지
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• 제23권1호
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• pp.13-20
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• 2018

Transverse acoustic mode in annular combustion chambers affects air-fuel mixing characteristics in the nozzle and can result in heat release fluctuations in the combustor. In addition, the acoustic mode coupling between the nozzle and the combustion chamber is one of the key parameters determining combustion instability phenomenon in the annular combustor. In this study, acoustic coupling between the nozzle and annular combustor was numerically analyzed using 3D-based in house FEM code. As a result, it was found that the acoustic mode inside the combustion chamber at anti-node locations of the transverse mode was strongly influenced by the nozzle inlet boundary conditions.

• Journal of the Optical Society of Korea
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• 제13권4호
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• pp.484-488
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• 2009

We investigate the characteristics of the surface mode formed at the single interface between dual singly negative medium layers. It is shown that the interface can support a mode which has polarization degeneracy and a vanishing propagation constant. That is, this surface mode is a polarization-independent one that does not propagate at all through the interface. The corresponding electric and magnetic field distributions become static along the longitudinal (guiding) direction (but not along the transverse direction) resulting in the formation of transverse-electric/longitudinalmagnetic or transverse-magnetic/longitudinal-electric modes.

• Computers and Concrete
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• 제13권4호
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• pp.569-585
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• 2014

In this paper, a four-layer road structure consisting of an edge transverse crack is simulated using three-dimensional finite element method in order to capture the influence of a single-axle wheel load on the crack propagation through the asphalt concrete layer. Different positions of the vehicular load relative to the cracked area are considered in the analyses. Linear elastic fracture mechanics (LEFM) is used for investigating the effect of the traffic load on the behavior of a crack propagating within the asphalt concrete. The results obtained show that the crack front experiences all three modes of deformation i.e., mode I, mode II and mode III, and the corresponding stress intensity factors are highly affected by the crack geometry and the vehicle position. The results also show that for many loading situations, the contribution of shear deformation (due to mode II and mode III loading) is considerable.