• Title/Summary/Keyword: Bottom friction

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Axial Load Transfer Behavior of a Large Diameter Drilled Shaft by Osterberg Type Load Test (오스트버그식 재하시험을 이용한 대구경 현장타설말뚝의 축하중전이거동)

  • 임태경;정창규;정성민;최용규
    • Proceedings of the Korean Geotechical Society Conference
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    • 2003.03a
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    • pp.447-454
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    • 2003
  • In this test, two separated oil jacks were placed at bottom of drilled shaft(D = 1,500mm, L = 33m), and maximum upward and downward load of 1,250 tonf was applied. Also, the deformable rod sensors were placed on each level, and axial strains at each level were measured. Because the side skin friction and the end bearing could be measured separately in the Osterberg type pile load test, this test might be more economical and more applicable than a conventional static pile load test. Thus, if this Osterberg type pile load test could be established during design stage, construction cost might be reduced and its application for large diameter pile could be enhance greatly.

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Seam Puckering Behavior of Breathable Waterproof Fabrics with Various Finishing Methods (가공방법에 따른 투습방수직물의 심 퍼커링 거동)

  • Jeong, Won-Young;Han, Won-Hee;An, Seung-Kook
    • Proceedings of the Korean Fiber Society Conference
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    • 2003.04a
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    • pp.402-403
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    • 2003
  • Garment manufacture represents the final stage of processing a finished fabric. The main task of the garment manufacturer is to produce shell structures out of flat fabrics to match the shape of the human body, and the most acceptable means of joining textile materials for apparel use is by sewing. On the sewing process, the bottom layer is pushed forward by the feed-dog, but the presser foot tends to retard the passage of the top layer. Since the friction between the layers is low, is possible that the components will move out of phase and pucker. (omitted)

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ADI Finite Difference Method of Linear Shallow Water Wave Equation (선형 천수방탁식의 ADI 유한차분법)

  • 이종찬;서승남
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.4 no.2
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    • pp.108-120
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    • 1992
  • An ADI model for linearized shallow water equation is modified using the method of factorization. In order to show its validity. the computational results are compared both with the analytical solution and with those from existing models, for a rectangualr domain with constant and varying amplitudes at the open boundary. It is shown the accuracy of numerical solutions depends on the size of time step. depth and bottom friction. The modified ADI model is shown to be superior to the existing models such as Leendertse (1971). Butler (1980) and Sheng (1983).

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Runup and Reflection of Waves on Impermeable Slopes of Coastal Structures (불투수성 경사면에서 파의 처오름과 반사)

  • Lee, Cheol-Eung
    • Journal of Industrial Technology
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    • v.21 no.B
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    • pp.175-185
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    • 2001
  • A numerical model is represented to calculate the reflected waves, the runup of waves and the wave induced velocities on impermeable slopes for the normally incident wave trains of nonlinear monochromatic wave and solitary wave. The finite amplitude shallow water equations with the effects of bottom friction are solved numerically in time domain using an explicit dissipative Lax-Wendroff finite difference method. The numerical model is verified by comparisons with the other numerical results, the measured data and asymptotic results. It is found that the uprushing and downrushing of incident waves may be accurately predicted by the present numerical model. Therefore, the present numerical model can be applicable to swells as well as long waves.

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A Study on the Prediction of Wave Deformation Model (파랑변형 모형의 예측에 관한 연구)

  • Ok, Chi-Yul;Min, Ill-Kyu
    • Journal of Ocean Engineering and Technology
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    • v.9 no.2
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    • pp.41-52
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    • 1995
  • the necessity of development of the Nearshore zone greatly emphasis in recent years. In the wave deformation model, we can get the wave height and wave direction using the hyperbolic mild slope equation considered the reflection wave. Radiation Stress the driving force of flow was calculated by the Watanabe and Maruyama who proposed on the partial standing wave. In the surf zone, applying the Izumiya and Horikawa's turbulent model considered the bottom friction and energy dissipation, we compared and examined with the Numerical model and Hydraulic test result of Watanabe and Maruyama. This model results obtained for Jin-ha Beach agreed well with the Numerical results. This model is expected so helpful to solve the prediction of the wave deformation problems in the development of the Nearshore zone in the future.

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Geostrophic Flows in a Container with a Vertical Plate (수직격판이 있는 용기 내의 지균류)

  • Choi, Yoon-Hwan;Suh, Yong-Kweon
    • Journal of Ocean Engineering and Technology
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    • v.13 no.4 s.35
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    • pp.124-131
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    • 1999
  • In this paper, we show the numerical and experimental results of two-dimensional fluid motions inside a rectangular container with a vertical plate subjected to a background rotation added by a rotational oscillation. In the PIV experiment we apply a new algorithm, NTSS, to the velocity calculation. In the numerical computation, the linear Ekman-pumping model was used to take the bottom friction effect into account. It was found that it showed good agreement with the experimental results at low ${\epsilon}$ number.

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A Study on Numerical Analysis for 2 Dimensional Circulation Model with Effect of Nonlinear Term (비선형항의 효과를 고려한 2차원 유동모형에 대한 수치해석연구)

  • 김희종;김진후;이상화
    • Journal of Ocean Engineering and Technology
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    • v.4 no.1
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    • pp.49-54
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    • 1990
  • This study describes the application of a two dimensional depth integrated numerical model. The explict scheme of finite difference method had been applied to the model of circulation. The nonlinear terms showed a slight difference for the variations of water elevation when calculated grid was small. They were also found to be minor when calculated grid size was increased. For verification of the numerical model, numerical results were compared with predicted values and field data. In the model, the effect of nonlinear advective terms proved not to be significant.

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Functional Requirements for VTS Decision Support System (VTS 의사결정지원 시스템 기능 요구 사항)

  • Lee, Sang-Woo;Lee, Byung-Gil
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2015.07a
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    • pp.338-339
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    • 2015
  • VTS Decision Support System can be defined a tool which assists VTS operator for decision-making at operational, planning and management level especially for the safety and efficiency of vessel traffic. This paper presents classification of VTS Decision Support System, detailed definition of alerts, and operational and functional requirements of VTS Decision Support System.

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Heat Transfer and Pressure Drop Characteristics of Triangular Ducts with One Side Rib-Roughened (한 측에서만 거칠기가 설치된 삼각덕트의 마찰계수와 열전달)

  • 안수환;이영석
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.2
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    • pp.17-23
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    • 2000
  • Experimental investigations were conducted to study the forced convection of fully-developed turbulent flow in horizontal equilateral duct fabricated with the same length and equivalent diameter, but different surface roughness pitch ratio(P/e) of 4, 8 and 16 on the one side wall only. The experiments were performed with the hydraulic diameter based Reynolds number ranged from 70,000 to 10,000. The entire bottom wall of the duct was heated uniformly and the other surfaces were thermally insulated. To understand the mechanisms of the heat transfer enhancement, measurements of the heat transfer were done to investigate the contributive factor of heat transfer promotion, namely, the fin effect. And the results were compared with those of previous investigations for similarly configured channels, at which they were roughened by regularly spaced transverse ribs in the rectangular and circular channels.

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A Study on the Numerical Models of Wave induced Currents (파랑에 의한 연안류의 수치모델에 관한 연구)

  • Lee, Jung-Maan;Kim, Jae-Joong;Park, Jung-Chul
    • Journal of Ocean Engineering and Technology
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    • v.12 no.3 s.29
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    • pp.75-85
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    • 1998
  • A finite difference model for predicting time-dependent, wave-induced nearshore current is studied. The model includes wave refraction, wave-current interaction, bottom friction and wind effect. This model iteratively solved the linear the linear set of conservation of both mass and momentum, which were time averaged (over one wave period) and depth integrated, for mean velocities and free surface displacement. Numerical simulations of nearshore current under oblique wave attack, and for wave and wind induced current on a longshore periodic beach are carried out. Longshore velocities tend to zero in some distances outside the breaker line. And the peak velocity is shifted shoreward at the breaker line. The results represent the general characteristics of the nearshore current induced by wave.

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