• 한국항공운항학회지
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• 제15권2호
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• pp.1-8
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• 2007

In this research, algorithm and software for the medium frequency signal analysis of DGPS(Differential Global Positioning System) station were developed. Based on new MF(Medium Frequency) algorithm, the software of NDGPS(National DGPS) signal analysis was developed for coverage analysis. Predicted MF propagation data from this software was compared to the measurement data for the verification of a developed MF algorithm. GIS(Geographic Information System) techniques including digital map with elevation data were used because MF propagation is closely related to ground conductivity, mountains, building intensity.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 1982년도 제24회 수공학 연구발표회 논문초록집
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• pp.3-24
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• 1982

The relations between tidal fluctuation and freshwater discharge are stuied dy use of observed data in the estuarine region of the Nagdong Rivre. Damping modulus which represents the resistance to propagation of tidal wave is estimated, and it is verified that when the fresh water discharge is lower than 300 m/sec., the elevation of mean-water-level at Gupo is the same as mean sea-water-level.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1992년도 가을학술발표회 논문집
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• pp.75-86
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• 1992

The elevation of reclamation work in the coastal area for the industrial complex is determined through the investigation and review of marine conditions, drainage plan and fill materials. The embankment to be constructed with crushed stone on the soft soil should be safe against the wave force, immediate and long term consolidation settlement, overturning and sliding due to self-weight and other forces. Because of lack of fill material from the borrow pit, the soft marine clay to be dredged shall be used as the reclamation material. And Paper Drain Board is used as the improvement method for the deep soft clay strata.

• 해양환경안전학회지
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• 제2권1호
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• pp.83-87
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• 1996

This study aims to investigate theoretically and experimentally second-order water level variation. The simple method obtaining second-order water surface elevation and mean water level applicable to both progressive and diffraction wave, mean water level set-down, as well as set-up occurs and it is shown to be in good agreement with the experimental results.

• 한국해양공학회지
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• 제15권1호
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• pp.12-18
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• 2001

This study concentrates on the second-order diffraction problem around circular cylinders in multi-frequency waves. The method of solution is a time-domain Rankine panel method which adopts a higher-order approximation for the velocity potential and wave elevation. In the present study, the multiple second-order quadratic transfer functions are extracted from the second-order time signal generated in random waves, and the comparison with other bench-mark test results shows a good agreement. This approach is directly applicable to prediction of nonlinear forces on offshore structures in random ocean.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1992년도 정기학술강연회 발표논문 초록집
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• pp.69-71
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• 1992

The local horizintal flux of tidal energy is characterized by the surface density $\omega$ = $\rho$ g h ζ u ($\rho$ - sea water density, g - gravitation, h - depth, ζ - tidal surface elevation, u - vertically averaged tidal current velocity vector). In general the flux vector $\omega$ comprises active and reactive components whose relation determines the local structure of a tidal wave.(omitted)

• 한국전자파학회논문지
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• 제7권2호
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• pp.95-104
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• 1996

임의의 평면파가 각진 두 도선에 입사시 관계변수들이 양단부하에 유기되는 전압에 미치는 영향을 조사하였다. 전송선 양단의 임피던스가 정합되고 입사파의 방향이 방위각과 고도각이 같을 때 유기전압이 최소가 됨을 알 수 있었다. 또한, 도선의 반경이나 도선간의 경사각이 변할 때 도표상에서 유기전압을 계산할 수 있는 방안도 제시하였다.

• 대한토목학회논문집
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• 제6권4호
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• pp.69-78
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• 1986

본 연구에서는 earth dam의 파괴로부터 야기되는 유출수문곡선을 유도하고, 홍수파가 자연하도를 통하여 하류로 전파되어 나가는 과정을 추적하기 위하여 dynamic wave equation을 구성하고, 이 식을 Preissmann scheme과 double sweep법을 이용하여 해석하는 DBF(Dam Break Floodwave) 요형을 개발하였다. 본 모형을 Teton dam에 적용하여 댐 파괴로 인한 홍수파의 첨두수위, 청두유량, 도달시간 및 범람 범위 등을 계산하였고, 실측자료와의 비교검토를 통하여 본 모형의 적용성을 입증하였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권4호
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• pp.670-690
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• 2015

In this paper, numerical investigations for tank sloshing, based on commercial CFD package FLUENT, are performed to study effects of boundary layer grid, liquid viscosity and compressible air on sloshing pressure, wave height and rising time of impact pressure. Also, sloshing experiments for liquids of different viscosity are carried out to validate the numerical results. Through comparison of numerical and experimental results, a computational model including boundary layer grid can predict the sloshing pressure more accurately. Energy dissipation due to viscous friction leads to reduction of sloshing pressure and wave elevation. Sloshing pressure is also reduced because of cushion effect of compressible air. Due to high viscosity damping effect and compressible air effect, the rising time of impact pressure becomes longer. It is also found that liquid viscosity and compressible air influence distribution of dynamic pressure along the vertical tank wall.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.597-605
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• 2019

This paper proposes a novel method for efficient prediction of joint distributions of heights and periods of nonlinear ocean waves. The proposed novel method utilizes a transformed linear simulation which is based on a Hermite transformation model where the transformation is chosen to be a monotonic cubic polynomial, calibrated such that the first four moments of the transformed model match the moments of the true process. This proposed novel method is utilized to predict the joint distributions of wave heights and periods of a sea state with the surface elevation data measured at the Gulfaks C platform in the North Sea, and the novel method's accuracy and efficiency are favorably validated by using comparisons with the results from an empirical joint distribution model, from a linear simulation model and from a second-order nonlinear simulation model.