• Title/Summary/Keyword: Shallow water effect

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Water Wave Propagation Caused by Underwater Blasting in a 3D Numerical Wave Tank (3차원 수치파동수조에서 수중발파에 의한 수면파의 전파해석)

  • Lee, Woo-Dong;Jeong, Yeon-Myeong;Choi, Kyu-Nam;Hur, Dong-Soo
    • Journal of Ocean Engineering and Technology
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    • v.33 no.4
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    • pp.364-376
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    • 2019
  • When underwater blasting is conducted, both shock waves and water waves have an effect on adjacent coastal areas. In this study, an empirical formula for estimating the details of water waves caused by underwater blasting was applied to a non-reflected wave generation system, and a 3D numerical wave tank (NWT) was improved to reproduce the generation and propagation of such water waves. The maximum elevations of the propagated water waves were comparatively analyzed to determine the validity and effectiveness of the NWT. Good agreement was demonstrated between the empirical and simulation results. The generation and propagation of water waves were also simulated under each underwater blasting scenario for the removal of the Todo islet at the Busan Newport International Terminal (PNIT). It was determined that the water waves generated by the underwater blasting scenario examined in this study did not have a significant impact on the PNIT. In addition, multiple-charge blasting caused higher wave heights than single-charge blasting. As the amount of firing charge increased, the wave height also increased. Finally, larger water waves were generated during the later blasting conducted at a deeper depth as compared with an earlier blasting conducted at a relatively shallow depth.

Applicability Analysis of an Improved Multistep Steel Pipe Grouting Method in Shallow Depth Railway Tunnels in Considering Safety and Constructability (저토피 철도터널구간의 안전 및 시공성을 고려한 개선된 강관다단 그라우팅 공법 적용성 분석)

  • Kim, Nakseok;Choi, Gisung;Kim, Seokhyun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.40 no.1
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    • pp.97-103
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    • 2020
  • The newly improved multistep steel pipe grouting method was applied to an existing steel pipe-reinforced grouting method. It was applied in order to prevent a damage caused by ground failure from excessive grouting pressure in a tunnel construction. The tunnel goes under a highway and a ramp connected to a rest area on OO highway with 11.3~12.1 m depth cover and is a part of roadbed facility construction section ordered by OO public corporation. The improved grouting method provides pre-construction work condition assessment technique through new water injection limit test and grouting effect assessment technique by grouting type assessment. It also includes assessments on interval of joints, appropriate grouting pressure, and optimal operation time to be applied to current operations. Application of the grouting method allowed the smooth road management in shallow-depth grouting construction area located upper part of tunnel excavation. Moreover, the possibility of the application of the method not only to shallow-depth grouting construction but also to various steel pipe-reinforced grouting constructions was confirmed.

Measuring Water Depth by Using a Combination of GPS/Echosounder (음향측심기와 위성항법을 이용한 하천의 수심 측량)

  • 정영동;강상구
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.20 no.4
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    • pp.375-381
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    • 2002
  • Depth of water information is obtained mainly from echo-sounding instrument which observes the round-trip time of signal from water surface to the bottom. Photogrammetry, underwater survey and laser survey etc. are also used as another method of bathymetric surveying. These methods are used specially for making track chart in a shallow water area. On the other hand, aircraft or satellite imagery ara also used in the sea area where the effect of suspended material is low and water quality is good. Presently, general bathymetric surveying has been performed in our country, but the spatial density of surveyed point are relatively low. Therefore, in this study we built a grid water depth chart which measured combing echosounder with GPS-RTK method and the depth accuracy was analyzed by using the data of direct survey water depth. As a results, the bathymatric mapping which use echosounder is more economical method compared to the existing methods.

Statistical Analysis on Water Quality Characteristics of Large Lakes in Korea (우리나라 주요 호소의 수질특성에 대한 통계적 분석)

  • Kong, Dongsoo
    • Journal of Korean Society on Water Environment
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    • v.35 no.2
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    • pp.165-180
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    • 2019
  • Water quality data of 81 lakes in Korea, 2013 ~ 2017 were analyzed. Most water quality parameters showed left-skewed distribution, while dissolved oxygen showed normal distribution. pH and dissolved oxygen showed a positive correlation with organic matter and nutrients, which appeared to be a nonsense correlation mediated by the algae. The ratio of $BOD_5$ and $COD_{Mn}$ to CBOD was 21 % and 52 % in the freshwater lakes, respectively. TOC concentration appeared to be underestimated by the UV digestion method, when salinity exceeds $700{\mu}S\;cm^{-1}$. In terms of nitrogen/phosphorus ratio, the limiting factor for algal growth seemed to be phosphorus in most of the lakes. Chlorophyll ${\alpha}$ increased acutely with decrease of N/P ratio. However, it seemed to be a nonsense correlation mediated by phosphorus concentration, since the N/P ratio depended on phosphorus. The N/P ratio of brackish lakes was lower than that of the freshwater, at the same concentration of phosphorus. It is worth examining denitrification that occurs, in bottom layer and sediment, during saline stratification. $Chl.{\alpha}$ concentration decreased in the form of a power function with increase of mean depth. The primary reason is that deep lakes are mainly at the less-disturbed upstream. However, it is necessary to investigate the effect of sediment, on water quality in shallow lakes. Light attenuation in the upper layer, was dominated by tripton (non-algal suspended solids) absorption/scattering (average relative contribution of 39 %), followed by CDOM (colored dissolved organic matter) (average 37 %) and $Chl.{\alpha}$ (average 21 %).

Analyses on the Behaviour of Ocean Structure Due to Ship Collision (선박의 충돌로 인한 해양구조물의 거동 해석)

  • 이호영;박종환;곽영기
    • Journal of Ocean Engineering and Technology
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    • v.15 no.4
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    • pp.115-119
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    • 2001
  • The simulation of motion responses of a dolphin-moored ocean structure in shallow water when it cllides with a ship, has been carried out. The equation of motion in the time domain according to Cummin's theory is employed, and solved by making use of the Newmark-${\beta}$ method. The added mass and damping coefficients involved in the equations are abtained from a three-dimensional panel method in the frequency domain. The impact forces due to ship collision are calculated using both the elastic and non-elastic modelings. The mooring forces for dolphin systems of ocean structure are regarded as linear spring forces.

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On the Study of Nonlinear Wave Diffraction by the Breakwaters (방파제 주위에서의 비선형 회절 현상에 대한 고색)

  • 조일형;김장환
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.5 no.4
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    • pp.350-356
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    • 1993
  • We carry out a numerical calculation to understand the nonlinear wave deformation around breakwaters using the Boussinesq equation, which is weakly nonlinear and weakly dispersive shallow water equation. A numerical method based on a finite element scheme and fourth order Runge-Kutta algorithm is employed to investigate the diffraction of incident waves by the breakwater. As a computational model, two-dimensional wave flume is treated. The breakwaters is perpendicular to the side wall of a channel. From the numerical results, the wave deformations according to the change of the length and the thickness of breakwaters are investigated. We also investigate the effect of the nonlinearity by comparing the results with the linear solutions.

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A Numerical Analysis of an Unsteady Flow in a Cavity Using an Ekman Pumping Model (에크만 분출 모델을 이용한 캐버티 내의 비정상 유동특성에 관한 수치해석)

  • 서용권;박춘근;최윤환;문종춘
    • Journal of Ocean Engineering and Technology
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    • v.11 no.4
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    • pp.102-110
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    • 1997
  • A two dimensional shallow-water flow around a cavity driven by a sinusoidally oscillating external flow was studied numerically with an Ekman pumping model. A container model of "T" shape was constructed in the numerical computation for comparison with the experimental observation. The material transport in the external region is in good agreement with the experimentally recorded particle trajectories. It turns out that two large coherent vortices situated in the exterior region of the cavity are responsible for clockwise and counterclockwise drift motions, in large scale, of particles. The Ekman pumping model suggested in this study was found to be satisfactory.isfactory.

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Decomposition of Reflecting Waves by Hyperbolic Model (쌍곡선형 모델에 의한 반사파 성분 분해)

    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.10 no.4
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    • pp.197-203
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    • 1998
  • An approach of decomposing the reflecting components is proposed by using the mild-slope equation of hyperbolic type which has the similar form to the shallow water equations. The approach is verified on Booij's problem and sinusoidally varying ripples. Inclusion of higher-order bottom effect given by chamberlain and Porter(1995) yields even more satisfactory results than the Berkhoff's mild-slope equation when compared with finite element solution or experiments.

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Redistribution of Passive Impurity by Long Waves in Coastal Zone (연안역에서의 장파에 의한 오염원 확산)

  • Ivanov, Vitaly;Pelinovsky, Efim;Talipova, Tatjana
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.5 no.3
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    • pp.232-239
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    • 1993
  • In this paper the effect of wave motion acting on the natural folds of dispersed material in the coastal zone is studied. After integrating the usual diffusion equation with respect to the depth using shallow-water approximation simpler equation for integrated concentration was obtained. which holds for long waves of arbitrary amplitude and far any arbitrary barotropic flows. Different situations of long wave action on impurity concentration in the frame of this equation are considered.

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Behaviour Analyses of Ocean Structure Due to Ship Collision (선박의 충돌로 인한 해양구조물의 거동 해석)

  • 이호영
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2001.05a
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    • pp.103-107
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    • 2001
  • When ship claps against the ocean structure sited at shallow water, the time simulation of motion responses of dolphin-moored ocean structure is presented. The equatien of motion based on Cummin's theory of impulse responses are employed, and solved in time domain by using the Newmark $\beta$ method. The added mass and damping coefficients involved in the equations are obtained from a three-dimensional panel method in the frequency domain. The impact forces due to ship collision are modeled as two method, and those are elastic and non-elastic collisions. The mooring forces for dolphin systems of scean structure are considered as linear spring system.

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