• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.434-445
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• 2020

In this study, the minimization of harbor oscillation using permeable breakwater was applied to the actual harbor and investigated an effect of minimization by computer simulation in order to take into account the water quality problems and measures of harbor oscillation by infragravity waves at the same time. The study site is Mukho harbor located at East coast of Korea that harbor oscillation has been occurred frequently. The infragravity waves obtained by analyzing the observed field data for five years focused on the distribution between wave periods of 40 s and 70 s and wave heights in less than 0.1 m was 94% of analyzing data. The target wave periods was 68.0 s. The most effective method of minimization of harbor oscillation by infragravity waves was to install a detached permeable breakwater with transmission coefficient of 0.3 on the outside harbor and replace some area of the vertical wall in the harbor with wave energy dissipating structure to achieve a reflectivity of 0.9 or less. The amplitude reduction rate of this method shown in 27.4%. And the effect of the difference in transmission coefficient of permeable breakwater on the reduction rate of the amplitude was not significant.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.2
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• pp.193-203
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• 1996

Long period waves were measured at two stations outside and inside Chukpyon Harbor using two pressure-type wave gauges for one week that covers storm sea period. Based on the collected data the characteristics of long-period resonant oscillations were analysed: the resonant period corresponding to the peak spectral density are slightly different from one to the component wave period with the largest amplification ratio, and the latter period is suggested as that of the first resonant mode. From the analysed field data and numerical modeling, the first resonant mode of Chukpyon Harbor region appeared to be around 12 minutes with amplification ratio of 7, whose amplitude varies 10-20 cm inside of the harbour, and also the second mode appeared to be around 6 minutes. The waves of 2-3 minute periods were resonated apparently in the harbour, which is considered to be generated from group-bounded irregular waves and non-linear wave-wave interaction etc. The linearly decreasing reflection coefficients used in the numerical modeling appeared to be an alternative in calculating reflected waves in harbor.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.1
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• pp.46-56
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• 1995

Three Pressure type wave gauges were installed for about 10 days for the analysis of long wave agitations in Mukho Harbor. Helmholtz and second resonant periods of seiche in Mukho Harbor are shown to be approximately 10.0-14.3 and 3.3 minutes from the spectral analysis of measured wave data. Amplification ratio at Helmholtz period reaches about 6.8 and the wave amplitudes in the harbor were in the range of 5-10 cm during the measurement period. Helmholtz and second resonant periods of seiche in Mukho Harbor agree very well with those computed using Jeong dt al. (1993b)'s model. The model gives rise to the first and third resonant peaks at 7.5 and 1.9 minutes, respectively.