• Journal of the Society of Naval Architects of Korea
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• v.55 no.1
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• pp.83-91
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• 2018

In this paper, usefulness of marine radar for water waves measurement in coastal waters is presented. We installed a marine radar to acquire radar images of water wave around light beacon at Jujeon in Ulsan. Also, a series of analysis procedures for obtaining the wave information from the acquired image is described with a schematic diagram. We compared analysis results of radar images with measurement values using wave height gauge at light beacon. In order to improve accuracy of analysis results, detailed water depth information is essential. In conclusion, in case of the use of radar for water waves measurement, it is shown that it is very necessary to increase the accuracy of measurement by consideration of the water depth in the dispersion relation of water waves.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.4
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• pp.295-302
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• 2007

Abnormally high waves occurring at the east coast of korea were observed at five field measurement stations and their characteristics were analyzed with the use of wind data provided by the Korean Meteorological Administration. The high waves occurred because strong Donghae twister that was developed by extratropical cyclone blew while high swell arrived at the east coast of Korea. At Sokcho, the most northern site among the five measurement stations, maximum gust speed was 63.7 m/s and significant wave height reached at its maximum of 9.69 m with the corresponding peak wave period of 12.8 s. The reason for appearance of the abnormally high waves is that high swell continued while the twister blew strongly. Moreover, the wind direction was the same as the direction of swell propagation, which maximizes the increase of wave height due to superposition of swell and wind-generated waves. On the east coast of Korea, outbreak of this type of storm waves is very probable in winter season so that it is requested to establish a countermeasure of minimizing possible damage caused by the storm waves.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.2
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• pp.132-137
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• 2003

Observations of internal waves in the southwest coastal waters of Korea have been made using a mooring measurement and satellite SAR together. From May 28 to May 30 in 2002, thermistor chains with RCM and ADCP mooring measurements were carried out at 10 kin west of Ocheong-Do, together with a CTD field sur-vey on the surrounding waters. Also, a SAR image was acquired on May 29 at 06:53. The data from the in-situ measurement show several internal wave packets passing through the mooring point and the SAR image reveals numbers of internal wave packets distributed around the point. Temporal and spatial characteristics of internal waves in the southwest coastal waters were analyzed using the data from mooring measurement, SAR image, and the K-dv equation. The internal waves are important phenomena in terms of physical oceanography and military as well as marine biology. They should be considered as one of important features in the southwest coastal waters in summer.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.12 no.1
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• pp.11-18
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• 2000

On the 25th of November in 1997 winter season, unprecedented high waves were recorded at the southern part of Korea Peninsular. The significant wave heights over 4 m were recorded at Marado, Pusan and Ulrungdo successively with time lags. Seoguipo breakwaters which were under construction were damaged by the unexpected high waves. These unprecedented southerly high waves in winter seem to be caused by unusual development and traveling of low pressure. Weather charts and wave fields calculated by a numerical model were analyzed to examine the unusual development of these waves. Protection against the southerly high waves in winter must be considered in coastal constructions and structures.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.2
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• pp.146-150
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• 1996

The waves are most important dynamical factors for the analyses of structural stability and topographical changes on coastal engineering field. However, wind-generated waves are very irregular in shape and transformed through refraction, diffraction and shoaling when they propagate into shallow water where bottom topography and water depth vary significantly. Recently, Vincent and Briggs (1989) reported hydraulic model experiments for the transformation of monochromatic and directionally-spread irregular waves passing over a submerged elliptical mound. They concluded that for the case of combined refraction-diffraction of waves by a shoal, the propagation characteristics of the irregular and equivalent regular wave conditions can be vastly different. On the irregular wave transformation have been made theoretical and numerical studies for several years. Although theoretical and laboratory studies on wave transformation have progressed considerably, field measurement and comparison of numerical results with related theories are still necessary for the prediction of the phenomena in reality. In this study, field measurement of both incident and transformed waves in Youngil Bay were made using various kinds of equipments, and numerical computations were made on the transformed frequency spectra of large waves propagating over the shoal using Chae and Jeong's (1992) elliptic model. It is shown that this model results agree very well with field data, and thus the applicability of the model is now validated.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.3
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• pp.212-220
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• 1993

A numerical model for the transformation of irregular waves in a coastal area is developed, which takes account of shoaling, refraction, diffraction, bottom friction and wave breaking. The governing equations are the usual energy conservation equation and kinematic conservation equations, but to consider the diffraction effects additional terms are included in the usual kinematic conservation or wave number equations. A linear superposition technique is used to represent the spectral formation. and an explicit formula is developed for the estimation of friction factor of irregular waves. A breaking criterion of component waves, which is the modified form of the Kitaigorodskii saturation relation, is employed to restrict the growth of shoaling waves in very shallow waters. The model was applied to a laboratory test and satisfactory agreement was obtained between the computation and measurement.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.3
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• pp.161-169
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• 2020

Physical experiments have been performed in a wave basin to investigate change of the wave loading on the crown wall under obliquely incident wave conditions. The measurement was carried out with wave incidence angle of 0, 15, 30 and 45°. The pressure transducers were placed on the front and bottom face of the crown wall to obtain horizontal and uplift force as well. It was found that both the horizontal and vertical force decreases with the incidence angle. Based on the analysis of the experimental data, a formula was suggested to estimate the reduction rate of horizontal and vertical forces under obliquely incident waves.

• International journal of advanced smart convergence
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• v.12 no.2
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• pp.182-186
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• 2023

In this study, we measured the power and temperature of the floating horizontal solar cell in a coastal lagoon and compared with those of ground solar cell and water platform solar cell. Because the bottom surface of the floating horizontal solar cell was contacting the water, cooling effect was expected stronger than other cells. As a result of the measurement, the power of floating horizontal cell was 11.7% higher than that of the ground cell and 15% higher than that of the water platform cell. During the measurement, it was observed that water waves were continuously flowed on the top surface of floating horizontal cell by the wind, and it could be assumed that the cooling effect occurred not only on the bottom surface of the cell but also on the top surface. In order to analyze the cooling effect and power increasing of the horizontal cell in the wave situation, we measured power and temperature of the cell while generating artificial waves in a laboratory equipped with Zenon lamp as a solar simulator. At the height of thewater surface, the power of the cell with waves was 3.7% higherthan without waves and temperature was 4.6℃ lower. At 1 cm and 2 cm below the watersurface, power of the cell with waves was decreased by 14% and 11% than without waves while temperature was same . At 3 cm below the water surface, there was no effect of waves.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.3
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• pp.117-123
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• 2016

One of the major characteristics of the swell-like high waves, which occur in the East Sea mostly in winter with large height and long period, is its suddenness associated with the rapid development of high waves from a calm state of sea. To represent such suddenness, in this study, the term sudden high waves is introduced. To propose the criterion of sudden high waves, comparisons were made between the wave measurement data at Gangneung and Wangdolcho for eight years from 2005 and the record of marine accidents and property damage on the coast of Gangwon-do Province and Gyeongsangbuk-do Province during the same period. It was found that most of the accidents occurred when ${\Delta}(H^2L)/{\Delta}t$ was approximately greater than the top 20% or $88.6m^3/hr$, which is therefore proposed as the criterion of sudden high waves. The used variable represents the rate of increase of the wave energy in one wavelength, including not only height and period but also suddenness of high waves.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.411-419
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• 2020

The experiment of unsteady rip current generated at the successive ends of breaking wave crests of honeycomb pattern waves was conducted in a laboratory wave basin, and its time-varying evolution was observed by using ortho-rectified images. The present experiment utilized the generation of a quasi nodal line of the honeycomb-pattern waves formed by out-of-phase motion of two piston-type wavemakers arranged in the transverse direction, instead of the original honeycomb pattern waves which are generated when two wave trains propagate with slightly different wave directions. The velocities of rip current were measured by using the LSPIV (Large-Scale Particle Image Velocimetry) technique. As a result, the unsteady rip current was generated between successive ends of wave crests, and evolved with its shear fluctuations in this experiment. Also, the time series of LSPIV velocity of the unsteady rip current showd its short component due to waves and its long component due to wave-induced currents.