• 한국전산유체공학회지
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• 제20권2호
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• pp.52-60
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• 2015

The objective of this research lies in the effect of installation parameters influencing on the wind proof performance of the coastal forest for damage prevention. The dissipation ratio of incident wind power is developed as an assessment index to make a lumped parameter study possible. From the real field data of East, West, and South Sea bounded on the Korean peninsula, single and double storied forests were modeled in three-dimensional shape with computer aided design, and so was done the artificial structures such as wind break, sand accumulating fence, and sand dune, etc With a commercial code ANSYS-CFX, the computational result from the comparison of dissipation ratio between single and double storied forest shows the effect of composition, and also the installation effect is investigated for artificial structures with optimal dimension of distance.

• Ocean and Polar Research
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• 제37권1호
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• pp.11-22
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• 2015

In-situ measurements are labor-intensive, time-consuming, and limited in their ability to observe currents with spatial variations in the surf zone. This paper proposes an optical image-based method of measurement of currents in the surf zone. This method measures nearshore currents by tracking in time wave breaking-induced foam patches from sequential images. Foam patches in images tend to be arrayed with irregular pixel intensity values, which are likely to remain consistent for a short period of time. This irregular intensity feature of a foam patch is characterized and represented as a keypoint using an image-based object recognition method, i.e., Scale Invariant Feature Transform (SIFT). The keypoints identified by the SIFT method are traced from time sequential images to produce instantaneous velocity fields. In order to remove erroneous velocities, the instantaneous velocity fields are filtered by binding them within upper and lower limits, and averaging the velocity data in time and space with a certain interval. The measurements that are obtained by this method are comparable to the results estimated by an existing image-based method of observing currents, named the Optical Current Meter (OCM).

• 한국항해항만학회지
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• 제28권7호
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• pp.619-627
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• 2004

Introduction of wave model, considered the effect of shoaling, refraction, diffraction, partial reflection, bottom friction, breaking at the coastal waters of complex bathymetry, is a very important factor for most coastal engineering design and disaster prevention problems. As waves move from deeper waters to shallow coastal waters, the fundamental wave parameters will change and the wave energy is redistributed along wave crests due to the depth variation, the presence of islands, coastal protection structures, irregularities of the enclosing shore boundaries, and other geological features. Moreover, waves undergo severe change inside the surf zone where wave breaking occurs and in the regions where reflected waves from coastline and structural boundaries interact with the incident waves. Therefore, the application of mild-slope equation model in this field would help for understanding of wave transformation mechanism where many other models could not deal with up to now. The purpose of this study is to form a extended mild-slope equation wave model and make comparison and analysis on variation of harbor responses in the vicinities of Ulsan Harbor and Ulsan New Port, etc. due to construction of New Port in Ulsan Bay. We also considered the increase of water depth at the entrance channel by dredging work up to 15 meters depth in order to see the dredging effect. Among several model analyses, the nonlinear and breaking wave conditions are showed the most applicable results. This type of trial might be a milestone for port development in macro scale, where the induced impact analysis in the existing port due to the development could be easily neglected.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 Asia Navigation Conference
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• pp.217-225
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• 2004

Introduction of wave model, considered the effect of shoaling, refraction, diffraction, partial reflection, bottom friction, breaking at the coastal waters of complex bathymetry, is a very important factor for most coastal engineering design and disaster prevention problems. As waves move from deeper waters to shallow coastal waters, the fundamental wave parameters will change and the wave energy is redistributed along wave crests due to the depth variation, the presence of islands, coastal protection structures, irregularities of the enclosing shore boundaries, and other geological features. Moreover, waves undergo severe change inside the surf zone where wave breaking occurs and in the regions where reflected waves from coastline and structural boundaries interact with the incident waves. Therefore, the application of mild-slope equation model in this field would help for understanding of wave transformation mechanism where many other models could not deal with up to now. The purpose of this study is to form a extended mild-slope equation wave model and make comparison and analysis on variation of harbor responses in the vicinities of Ulsan Harbor and Ulsan New Port, etc. due to construction of New Port in Ulsan Bay. This type of trial might be a milestone for port development in macro scale, where the induced impact analysis in the existing port due to the development could be easily neglected.

• 한국연안방재학회지
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• 제4권3호
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• pp.119-131
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• 2017

Global warming under the influence of climate change and its direct impact on glacial and sea level are known issue. However, there is a lack of research on an indirect impact of climate change such as coastal structure design which is mainly based on a frequency analysis of water level under the stationary assumption, meaning that maximum sea level will not vary significantly over time. In general, stationary assumption does not hold and may not be valid under a changing climate. Therefore, this study aims to develop a novel approach to explore possible distributional changes in annual maximum sea levels (AMSLs) and provide the estimate of design water level for coastal structures using a multiple non-crossing quantile regression based nonstationary frequency analysis within a Bayesian framework. In this study, 20 tide gauge stations, where more than 30 years of hourly records are available, are considered. First, the possible distributional changes in the AMSLs are explored, focusing on the change in the scale and location parameter of the probability distributions. The most of the AMSLs are found to be upward-convergent/divergent pattern in the distribution, and the significance test on distributional changes is then performed. In this study, we confirm that a stationary assumption under the current climate characteristic may lead to underestimation of the design sea level, which results in increase in the failure risk in coastal structures. A detailed discussion on the role of the distribution changes for design water level is provided.

• 한국연안방재학회지
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• 제4권3호
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• pp.111-118
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• 2017

In this study, pull box members were designed by finite element analysis of a steel plate covering a pull box to secure its safety on the landing pier dedicated to the large research survey ship. It was assumed that the maximum load is due to the 250 tonf class crane used for unloading work when the working environment in the upper part of the landing pier was considered. The safety of the pull box was evaluated by the comparison between the yield strength of the steel plate and the result of stress analysis on the steel plate due to the crane load. It was found that the stress at the plate from the crane load exceeded the yield strength of the steel(205MPa) when the upper part of the pull box was protected by a $1950{\times}1950mm$ steel plate cover. In order to compensate for this, a concrete filled steel tube(CFT) column with a diameter of 150 mm and a steel thickness of 10 mm was reinforced at the center of the plate, and the finite element analysis was carried out. However, the maximum stress at the steel plate was higher than the yield strength of the steel in some load cases so that it was tried to find appropriate thickness of the steel plate and diameter of the CFT columns. Finally, the analysis results showed that the safety of the pull box was secured when the thickness of the steel plate and the diameter of the CFT column were increased to 30mm and 180mm, respectively.

• 한국해안·해양공학회논문집
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• 제22권1호
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• pp.58-66
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• 2010

본 논문에서는 지상 LiDAR 및 MBES(다중빔 음향측심기)를 이용하여 정밀 지형 및 수심측량을 실시하였고, 조간대 영역의 육도-해도 접합을 통하여 대조차 해안인 만리포에 대한 정밀 지형도를 작성하였다. 제한된 시간내에 조간대 영역의 충분한 지형정보 획득을 위하여 간조시 지상 LiDAR 및 DGPS를 차량지붕에 탑재하여 이동 정지 스캐닝의 해변 전체의 지형정보를 획득하였고, 이와 동시에 만조시 MBES를 통하여 수심측량을 실시하였으며 조위계 설치와 목측을 통한 조위관측의 병행을 통하여 수심보정자료 및 만리포의 평균해면 추산자료로 사용하였다. 조간대 정합을 위해 지형 및 수심자료의 수직좌표계 기준면은 인천 평균해면으로 단일화하였으며, 조간대 평균 중첩오차는 약 2~6 cm 이내로 나타났다. 또한 지상 LiDAR 자료의 정확도 검증을 위해 RTK-DGPS 측량을 동시에 실시하여 수직좌표값을 비교한 결과 평균 제곱근 오차가 약 4~7 cm 이내로 나타났다. 정밀지형도 작성은 GIS 기반 자료처리를 통하여 50 cm 해상도를 갖는 수치표고자료로 생산하였으며, 이는 현재 연안지역 침수범람 예측을 위한 폭풍해일 침수범람 예측모델의 정밀 입력자료로 사용되고 있다. 또한 장기간에 걸친 주기적 측량 자료와 측량시의 인위적 해변 변화량 및 해양환경정보를 함께 고려하여 3차원 공간분석을 실시한다면 침 퇴적양의 정확한 산출을 통하여 연안 모니터링에도 효과적으로 활용될 수 있을 것이다.

• 한국지반신소재학회논문집
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• 제15권3호
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• pp.39-47
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• 2016

해상 폐기물매립지에서 내부 침출수의 외부 유출을 방지하기 위하여 차수공이 필수적으로 요구된다. 이를 위해 경사식 호안의 경우에는 사면부에 차수시트가 설치된다. 사면부에 설치된 차수시트의 하부 지반에서의 연장설치범위에 따른 침투차단효과를 평가하기 위하여 SEEP/W를 이용하여 침투해석을 실시하였다. 해석결과, 해저지반에 저투수성 지층이 분포되어 있으면 차수시트를 호안 사면끝단으로부터 점토층 상부면으로 1m 이상 연장하여 설치하여야 침투방지에 효과가 있는 것으로 나타났다. 하부지반에 투수성이 큰 사질토층이 존재하는 경우에는 폭 1m 이상을 저투수성으로 개량하고 차수시트를 1m 이상 연장하여 설치하는 것이 효과적인 것으로 나타났다.

• Ocean and Polar Research
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• 제33권3호
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• pp.291-301
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• 2011

To investigate major factors controlling variations in water quality, principal component analysis and cluster analysis were used to analyze data sets of 12 parameters measured at 23 sampling stations of Jinhae Bay during winter and spring. Principal component analysis extracted three major factors controlling variations of water quality during winter and spring. In winter, major factors included freshwater input, polluted material input, and biological activity. Whereas in spring they were polluted material input, freshwater input, and suspended material input. The most distinct difference in the controlling factors between winter and spring was that the freshwater input was more important than the polluted material input in winter, but the polluted material input was more important than the freshwater input in spring. Cluster analysis grouped 23 sampling stations into four clusters in winter and five clusters in spring respectively. In winter, the four clusters were A (station 5), B (stations 1, 2), C (station 4), and D (the remaining stations). In spring, the five clusters included A (station 5), B (station 1), C (station 3), D (station 6), and E (the remaining stations). Intensive management of the water quality of Masan and Hangam bays could improve the water quality of Jinhae Bay since the polluted materials were mainly introduced into Jinhae Bay through Masan and Hangam bays.

• Ocean and Polar Research
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• 제33권spc3호
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• pp.385-395
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• 2011

Time-series sediment traps were deployed at 1,000 m water depth of the northwestern subtropical Pacific from July 2009 to June 2010, with the aim of understanding temporal and spatial variations of sinking-particle fluxes. The opening and closing of the traps was synchronized at 18-day periods for 20 events. Total mass fluxes showed distinct seasonal variations with high values for the summer-fall seasons and relatively low values for winter-spring. This seasonal variation at two stations was characterized by a distinct difference in $CaCO_3$ fluxes between the two seasons. The enhanced $CaCO_3$ flux in the summer - fall seasons might be attributed to an increased planktonic foraminiferal flux. Total mass flux at FM10 station was nearly 50% higher than that at FM1 station. The difference in $CaCO_3$ fluxes between two stations contributed nearly 70% of the difference of total mass fluxes. The $CaCO_3$ flux was a major component controlling temporal and spatial variation of sinking - particle fluxes in the western subtropical Pacific Ocean.