• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.3
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• pp.216-222
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• 2010

The structural methods used to protect coastal erosion are usually very expensive in construction as well as in spending on maintaining the structures from damage. Those structures like embankments, breakwaters, jetties etc. are commonly constructed with concretes (rigid methods) to protect coastal erosion. But those rigid methods are not effective always, because the wave energy and impact force on the structures could not be effectively reduced by those methods. For avoiding sediment erosion on coastal areas by the way of reducing wave energy, a flexible breakwater is introduced which will reduce energy and protect coastline economically and environmentally. The flexible device is a combination of flexible wire nets and stack of rings made of used vehicle tires and soft blades on surfaces. This flexible wire net is placed in between two stacks of rings. The stack of rings is mainly used to hold the flexible wire nets and the flexible wire net is mainly used to reduce wave energy and helps to deposit sediments in coastal area. For a field experiment study, the above-mentioned flexible breakwater of coastal protection has been set up at the Shuang-Chun coastal area in Tainan County since June 10, 2009. The length of the flexible device is 50.0 meters and the height is 2.0 meters. The function of the device has been examined by Typhoon Linfa during June 19~22, 2009 and by Typhoon Morakot during August 6~10, 2009. The result shows that the flexible breakwater has effectively trapped sediments and let them deposit on coastal. The depth of sediment deposition around the device was about 0.5 to 0.8 meters.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.117-124
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• 2005

Recently the first stage of construction for Busan new port emerged over the sea surface at the north container terminal site. With this, there are lot of discussions and debates on increasing the water depth at the approaching channel and mooring basin from the existing 15m to 18m by dredging work in order to be able to serve 12,000TEU containership, and at the same time, correction to the reclamation plan of hinterland at the part of Undong Bay of the new port site. Since the attack of typhoon 'Maemi' in 2003, it is expected that the design wave parameters for coastal and harbor structures in this area would be somewhat changed and so the extreme wave condition at each terminal and tranquility of berthing area does, and therefore, it is necessary to analyze the tranquility at each berth. Hence in this study, we constructed a wave model for these conditions and performed simulation together with the circulation model simulation, compared with the field data collected. The result showed the increase of the harbor response throughout the basin but not severe condition. However, a certain location needs to be prepared for the rough sea condition when a severe typhoon hit the site.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.5
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• pp.571-576
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• 2015

This paper presents a comparative study of wave height estimation method that was used for signal to noise ratio and shadowing ratio based on X-band marine radar. If the signal to noise ratio, and is widely used as a method for estimating an wave height, a new method is presented for shadowing ratio. In the case of radar images used in this study it is measuring the data from the coast of Ulsan Jujeon, compared with marine meteorological information from the Meteorological Agency measured a light beacon. We compared the measured data for about 34 days, the typhoon was measured, incluidng a period in the East Sea, and verify the results for various distribution of wave height. For estimate wave height using a shadowing ratio analysis, it does not require calibration and real-time advantages of this part, coming confirmed the possibility of the measurement, the cause detection error for radar image was caused due to determine.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.329-329
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• 2017

In this study attempted to evaluate the stability of the protection methods by examining hydraulic characteristics of the area around the point in which marine cable protector is installed such as surf zone occurrence point of shore-end submarine cables suitable for coastal marine environmental conditions, flow rate t the tope of the protector and maximum wave height, and to provide basic data for the selection of the optimal protection method. In performing hydraulic model experiments, the topography of submarine cable installation location was reproduced in 2-D sectional channel, and models appropriate for experimental scale and similitude law were produced and installed for each condition of submarine cables and protectors. Since the topography and submarine cable protectors were reproduced and installed in 2-D sectional channel, the exact reproduction of surf and transformation in shallow water zone was possible, and thus the physical properties could be clearly analyzed. For stability review, an experiment to examine the stability was conducted using a wave maker with 50-year frequency design waves as target, and wave height and cycles were applied based on the approximate lowest low water level(Approx. L.L.W), which is the most dangerous in submarine cable protection methods. As for experimental time, typhoon passing time in summer (about 3 hours) was applied, and wave patterns and deviation ratio of the submarine cable protector were investigated after making irregular waves corresponding to design waves. In addition, current meter and wave height meter were installed at the installation location of the submarine cable protector, and the flow rates and wave height at the top of the protector were measured and analyzed to review hydraulic properties.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.5
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• pp.599-607
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• 2015

The purpose of this study is to reproduce long-term wave fields in coastal waters of Korea based on wave hind-casting modelling and discuss its applications. To validate wind data(NCEP, ECMWF, JMA-MSM), comparison of wind data was done with wave buoy data. JMA-MSM predicted wind data with high accuracy. But due to relatively longer period of ECMWF wind data as compared to that of JMA-MSM, wind data set of ECMWF(2001~2014) was used to perform wave hind-casting modelling. Results from numerical modelling were verified with the observed data of wave buoys installed by Korea Meteorological Administration(KMA) and Korea Hydrographic and Oceanographic Agency(KHOA) on offshore waters. The results agree well with observations at buoy stations, especially during the event periods such as a typhoon. Consequently, the wave data reproduced by wave hind-casting modelling was used to obtain missing data in wave observation buoys. The obtained missing data indicated underestimation of maximum wave height during the event period at some points of buoys. Reasons for such underestimation may be due to larger time interval and resolution of the input wind data, water depth and grid size etc. The methodology used in present study can be used to analyze coastal erosion data in conjunction with a wave characteristic of the event period in coastal areas. Additionally, the method can be used in the coastal disaster vulnerability assessment to generate wave points of interest.

• Journal of Navigation and Port Research
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• v.48 no.3
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• pp.192-199
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• 2024

Wave overtopping is a significant natural hazard that occurs in coastal areas, primarily driven by high waves, particularly those generated during typhoons, which can cause coastal flooding. The development of residential and commercial areas along the coast, driven by increasing social and economic demands, has led to a concentration of people and assets in these vulnerable areas. This, coupled with long-term sea level rise and an increase in typhoon frequency, has heightened the risk of coastal hazards. Traditionally, the evaluation of wave overtopping volumes has relied on directly measuring the collected volume of water that exceeds the crest height of structures through hydraulic model experiments. These experiments are averaged over a specific measurement period. However, in this study, we propose a new method for estimating individual wave overtopping volumes. We utilize the temporal variation of wave overtopping heights to develop an observation system that can quantitatively assess wave overtopping volumes in actual coastal areas. To test our method, we conducted hydraulic model experiments on rubble mound breakwaters, which are commonly installed along the Korean coast. We introduce wave overtopping discharge coefficients, assuming that the inundation velocity from the structure's crest is the long-wave velocity. We then predict overtopping volumes based on wave overtopping heights and compare and review the results with experimental data. The findings of our study confirm the feasibility of estimating wave overtopping volumes by applying the overtopping discharge coefficients derived in this study to wave overtopping heights.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.6
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• pp.286-297
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• 2018

In the present study, wave measurements at KOGA-W01 were analyzed and then the numerical wind waves simulations have been conducted to investigate the characteristics of wind waves in the Yellow sea. According to the present analysis, even though the location of the wave stations are close to the coastal region, the deep water waves are prevailed due to the short fetch length. Chun and Ahn's (2017a, b) numerical model has been extended to the Yellow Sea in this study. The effects of tide and tidal currents should be included in the model to accommodate the distinctive effect of large tidal range and tidal current in the Yellow Sea. The wave hindcasting results were compared with the wave measurements collected KOGA-W01 and Kyeockpo. The comparison shows the reasonable agreements between wave hindcastings and measured data, however the model significantly underestimate the wave period of swell waves from the south due to the narrow computational domain. Despite the poorly prediction in the significant wave period of swell waves which usually have small wave heights, the estimation of the extreme wave height and corresponding wave period shows good agreement with the measurement data.

• Journal of Korea Multimedia Society
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• v.15 no.2
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• pp.258-265
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• 2012

Our country is suffering from many human victims and property damages caused to occur great and small tidal waves in southern areas every year. Even though there were progressing many researches for storm surges, it was required more researches for detection of tidal wave and prevention system of its which can be applied in practical living fields. In this paper, we propose the disaster prevention system that can approximately detect a dangerousness of coast flooding and number of overtopping per time based on images of CCTV considering actual field application. And if it is detected a hazard of flooding of coast, the proposed detection system for tidal wave based GIS is quickly informed the areas of flooding to manager. The analyzing results of CCTV image of this proposed are derived from difference images between photos of fine day and photos or videos which are taken for the typhoon which is called "DIANMU" at our laboratory.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.4
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• pp.1-7
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• 2007

Using field observations, this study estimated the total weight and types of marine debris along the coast of Jinu Island in the Nakdong River Estuary after typhoons Usagi and Nari had passed. A numerical wave model was used to calculate the spatial wave height distribution at the time of the typhoons' passage. This study found that the total accumulation rate of marine debris deposited on the coast after the two typhoons had passed was about $5,769.86\;kg/km^2/day$ at this site, which was 14.42 times as high as that in normal weather. The wave height distribution in the sea off Jinu Island, based on numerical modeling, was $4.1{\sim}3.5\;m$, which was 1.0-2.5 times greater than for the case of other islands. Therefore, it is likely that the concentration of wave energy led to the deposition of marine debris.

• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.15-21
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• 2007

Using field observations, this study estimated the total weight and types of marine debris along the coast of Jinu Island in the Nakdong River Estuary after typhoons Usagi and Nari had passed. A numerical wave m며el was used to calculate the spatial wave height distribution at the time of the typhoons' passage. This study found that the total accumulation of marine debris deposited on the coast after the two typhoons had passed was about $5,769.86kg/day/km^2$ at this sitε which was 14.42 times more than during normal weather. The wave height distribution in the sea off Jinu Island, based on numerical modeling， was $4.1^{\sim}3.5$ m, which was 1.0-2.5 times greater than for the case of other islands. Therefore, it is likely that the concentration of wave energy led to the deposition of marine debris.