• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.102-107
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• 2013

It is important to understand the vibrating behavior of plate structures for many engineering applications. In this study, vibration characteristics of strip plates which have finite width and infinite length are investigated theoretically and numerically. The waveguide finite element approach is used in this study which is known as an effect tool for waveguide structures. WFE method requires only cross-sectional FE model and uses theoretical harmonic solutions for the wave propagation along the longitudinal direction. First of all for a simple strip plate, WFE results are compared with theoretical ones such as the dispersion diagrams, point mobilities, etc. to validate the numerical model. Then in the numerical analysis, the several different types of longitudinal stiffeners are included to the plate model to investigate the effects of the stiffeners in terms of the dispersion curves and mobilities.

• 한국철도학회논문집
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• 제7권3호
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• pp.200-207
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• 2004

Theoretical study has been conducted to clarify pressure characteristics of KTX (Korea Train eXpress) in tunnel. The severe pressure change in tunnel may give rise to the ear-discomfort for passenger and fatigue for car body. Critical tunnel lengths which are induced by x-t diagram analysis can be applied to the experimental results measured by using the running test with atmospheric pressure sensors and portable data acquisition system in previous study. In this study, the tunnels from 200m to 4000m in length have been chosen for the investigation of tunnel length effects. We found that there are similar patterns of external pressure change for each critical tunnel length. The critical tunnel lengths are governed by train speed, train length and sonic velocity. And, the patterns of pressure wave in tunnel are classified into eight groups.

• 한국항만학회지
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• 제8권2호
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• pp.57-65
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• 1994

A theoretical formulation is performed to investigate the wave reflection and transmission ratios by a submerged multi-layered rubble-mound breakwater. This theory, which is based on the linear boundary integral method, can be extended to the multi-layered breakwater with arbitrary cross section. In the theoretical analysis evanescent mode wave is not considered, since fictitious open boundaries are put on the places far from the structure. Therefore the mathematical presentation may be simpler, and computational time shorter. The validity of obtained numerical results is demonstrated by comparing with ones of impermeable and permeable breakwaters. Comparison shows resonable agreement. On the basis of these verifications this theory is applied to the one and two-layered submerged rubble-mound breakwater with trapezoidal type.

• 대한전자공학회논문지
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• 제7권2호
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• pp.13-20
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• 1970

진행파형 메이저에 사용할 수 있는 테이프 메안더라인의 지연방정식을 전자계의 쌍대성에 의하여 유도하였다. 프린트동판을 포토칭하여 메안더라인을 제작하였으며, 메안더라인의 공극폭, 테이프폭, 회로폭의 변화에 따른 지연곡선의 변화를 상위브릿지 방법으로 측정하여 이론곡선과 비교고찰하였다.

• Journal of the Korean Physical Society
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• 제73권9호
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• pp.1247-1254
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• 2018

We study the uncertainty stemming from different theoretical models in the spectroscopic factors extracted from experiments. We use three theoretical approaches, the distorted wave Born approximation (DWBA), the adiabatic distorted wave approximation (ADWA) and the continuum discretized coupled-channels method (CDCC), and analyze the $^{12}C(d,p)^{13}C$, $^{14}C(d,p)^{15}C$ reactions. We find that the uncertainty associated with the adopted theoretical models is less than 20%. We also investigate the contribution from the remnant term and observe that it gives less than 10% uncertainty. We finally make an attempt to explain the discrepancy in the spectroscopic factors of $^{17}C(\frac{3}{2}^+)$ between the ones extracted from experiments and from shell model calculations by analyzing the $^{16}C(d,p)^{17}C$ reaction.

• 한국해양공학회지
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• 제23권1호
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• pp.43-47
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• 2009

This paper compares theoretical wave profile and particle kinematics with experimental results generated by a 2 D wave tank. Particle velocity fields of compound waves were acquired using a PIV technique. Synchronization was applied to acquire images of the wave fields, and the time gap between these images was controlled by the user. This technique was applied to investigate the wave breaking mechanism, and the wave profile and velocity distribution in a wave breaking field was obtained.

• 한국기계연구소 소보
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• 통권9호
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• pp.153-167
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• 1982

From first-order thin-ship theory, we can obtain the" wave resistance, wave amplitude functions, wave elevation along the hull, sinkage and trim of a ship moving with constant speed into calm water. Generally, these calculations of ship is called with Michell’s Theory, and there is all the difference between calculated wave resistance and residual resistance from conventional wave resis¬tance test. But, these calculated results are important reference materials for initial hull form design procedure. Various calculated results for Shearer’ s Model, Wigley’s Model and Series 60 4210W Model have been calculated using this theory. The results are compared with the corresponding experimental values, and the agreement between theoretical and experimental values is considered satisfactory.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.851-856
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• 2003

This paper proposes a single-mode Lamb-wave generation and detection system using a pulsed laser as a generator and an air-coupled transducer combined with the wavelet transform analysis, as the detector. The laser source with arrayed linear slits was used to generate Lamb-wave which is able to control the wavelength of Lamb-wave to be generated by changing the slits separation. An ari-coupled transducer was used to receive Lamb-wave, which can selectably receive a single mode of leaky Lamb wave by changing the oblique angle of transducer, since the leaky Lamb-wave has unique leaky-angle according to the mode. Also, the received signal was processed by wavelet transform for the analysis in domain of time-frequency. The theoretical dipersion curve and the experimetal result was compared to show good agreement.

• 한국해양공학회지
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• 제23권4호
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• pp.6-11
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• 2009

In this study, the internal waves in two-density layered fluids were analyzed using the Numerical Wave Tank (NWT) technique in the frequency domain. The NWT is based on a two-domain Boundary Element Method with the potential fluids using the whole-domain matrix scheme. From the mathematical solution of the two-domain boundary integral equation, two different wave modes could be classified: a surface wave mode and an internal wave mode, and each mode were shown to have a wave number determined by a respective dispersion relation. The magnitudes of the internal waves against surface waves were investigated for various fluid densities and water depths. The calculated results are compared with available theoretical data.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.147-150
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• 2002

In general, a single gas flow through a converging nozzle is choked when the pressure communications between the downstream and upstream flowfields are broken by the sonic condition of Mach number, M=1. A similar phenomenon may occur In two streams of different stagnation properties flowing side by side in a converging nozzle. In this case, the limiting condition of M=1 for flow choking is no longer applied to such a compound compressible flow. The compound choking phenomenon can be explained by means of a compound sound wave at the nozzle exit. In order to detail the flow characteristics involved in such a compound choking of the two streams, the two-dimensional, compressible, Wavier-Stokes equations have been solved using a fully implicit finite volume method and compared with the results of the one-dimensional theoretical analysis. The computational and theoretical results show that the compound sound wave can reasonably explain the compound choking phenomenon of the two streams in the convergent flow channel.