• Journal of Korean Society of Water and Wastewater
• /
• v.23 no.5
• /
• pp.517-526
• /
• 2009

This research has been conducted to investigate the characteristics of hydraulic behavior within the PAC contactor, the rectangular shape sedimentation basin without inclined tube and the other one with inclined tube those are parts of demonstration plants(capacity : $2,000m^3/d$) in Korea Institute of Water and Environment. As results of tracer tests, the flow within PAC contactor was evaluated to divided into plug flow and dead space distinctly, and characteristics of dead space was close to that of CSTR(Complete/continuous Stirred Tank Reactor). Also, considering Reynolds number, Froude number, Morill, Modal, NCSTR Inex and plug flow/mixed flow fraction, in the case of the rectangular shape sedimentation basin without inclined tube, the characteristics of flow pattern was close to CSTR. On the other hand, in the case of the basin with inclined tube, the region of CSTR decreased precisely compared with the case of no-tube. Until now we have recognized that the inclined hydraulic structure just reduces the surface loading rate within a sedimentation basin. Actually besides, the inclined structure have an important effect on the hydraulic behavior within the basin.

• Journal of Korean Society on Water Environment
• /
• v.21 no.1
• /
• pp.40-45
• /
• 2005

Sedimentation is one of the most common and important units in conventional water treatment plant. Structure such as various baffle walls and inclined plate settler may be obstacles to the horizontal flow when it is poorly designed. Therefore, the effects of these structures on characteristics of hydraulic flow must be evaluated to improve the settling efficiency of the floc. The hydraulic characteristic of the two sedimentations at Y water treatment plant (YWTP), which have different deflector baffles inside the settling basin, were investigated by tracer (fluoride) test. The inclined plate settler installed inside settling basin caused an undesirable impact on horizontal flow and produced dead zone. Solid baffle wall under the plate settler could help to minimize the formation of density currents and flow short circuiting. NaF used as a tracer was recovered more than 90% at investigated all basins. Morill index ($t_{90}/t_{10}$), Modal index ($t_p/T-HRT$) and short-circuiting index ($[M-HRT-t_p]/M-HRT$) were determined from tracer test results performed at YWTP. Those indices ranged 2.95~3.02, 0.40~0.53 and 0.32~0.46, respectively.

• Journal of Korean Society of Water and Wastewater
• /
• v.18 no.4
• /
• pp.427-436
• /
• 2004

Sedimentation is one of the most common and important units in conventional water treatment plants. Structure such as various baffle walls and inclined plate settler may be obstacles to the horizontal flow when it is poorly designed. Therefore, the effects of these structures on characteristics of hydraulic flow must be evaluated to improve the settling efficiency of the floc. The hydraulic characteristic of the four sedimentations at the three real WTPs (water treatment plants), which have different structural properties respectively inside the settling basin, were investigated by tracer (fluoride) test. The inclined plate settler installed inside settling basin caused a undesirable impact on horizontal flow and produced dead zone. Intermediate baffle and solid baffle wall under the inclined plate settler at GE plant help to minimize the formation of density currents and flow short circuiting. However, installing perforated baffle under the inclined plate settler at other plants could not induce even distribution of flow. NaF used as a tracer was recovered more than 90% at investigated all basin. Morill index ($t_{90}/t_{10}$), Modal index ($t_p/T-HRT$) and short-circuiting index ($[M-HRT-t_p/M-HRT$) were determined from tracer test results performed at three WTPs. Those indices ranged 2.99~3.45, 0.44~0.72 and 0.23~0.47, respectively.

• Journal of Navigation and Port Research
• /
• v.30 no.8 s.114
• /
• pp.649-655
• /
• 2006

Waves progressing into the coastal area can be amplified, swashed and overtopped by a wave overtopping control structure, and it converts the kinetic energy of the waves to the potential energy with a hydraulic head above the mean sea level by conserving the overflow in a reservoir. Then the potential energy in the form of hydraulic head can be converted to electric power utilizing extremely low-head hydraulic turbine. This study aims to find the most optimal shape of wave overtopping structure which maximizes overtopping volume rate of sea water. Laboratory experiments for the performance evaluation of wave overtopping control structures were carried out in three dimensional wave tank, and the three dimensional structure models with planar wave concentration shapes(B/b) were manufactured into five classes, which were optimized by cross sectional parameters of the structure, ie, length of ramp(l), gradient of inclined ramp($cot{\phi}$) and freeboard height of the wave overtopping structure($h_e$) proposed by Shin and Hong(2005). The wave overtopping discharges were investigated with 20 incident wave conditions and wave directions of $0^{\circ},\;15^{\circ},\;30^{\circ}$.

• Wind and Structures
• /
• v.31 no.6
• /
• pp.533-548
• /
• 2020

Despite the current technologic developments, failures in existent tensile fabric structures (TFS) subjected to wind do happen. However, design pressure coefficients are only obtained for large projects. Moreover, studies on TFSs with realistic supporting frames, comparing static and dynamic analyses and discussing the design implications, are lacking. In this study, fluid-Structure analyses of a TFS supported by masts and inclined cables, by subjecting it to different wind speeds, are carried out, to gain more understanding in the above-referred aspects. Wind-induced stresses in the fabric and axial forces in masts and cables are assessed for a hypar by using computational fluid dynamics. Comparisons are carried out versus an equivalent static analysis and also versus loadings deemed representative for design. The procedure includes the so-called form-finding, a finite element formulation for the TFS and the fluid formulation. The selected structure is deemed realistic, since the supporting frame is included and the shape and geometry of the TFS are not uncommon. It is found that by carrying out an equivalent static analysis with the determined pressure coefficients, differences of up to 24% for stresses in the fabric, 5.4% for the compressive force in the masts and 21% for the tensile force in the cables are found with respect to results of the dynamic analysis. If wind loads commonly considered for design are used, significant differences are also found, specially for the reactions at the supporting frame. The results in this study can be used as an aid by designers and researchers.

• Journal of Navigation and Port Research
• /
• v.41 no.5
• /
• pp.345-352
• /
• 2017

Recently, a new port reserves deep water depth for safe navigation and mooring, following the trend of larger ship building. Larger port facilities include long and huge breakwaters, and mainly adopt vertical type considering low construction cost. A vertical breakwater creates stem waves combining inclined incident waves and reflected waves, and this causes maneuvering difficulty to the passing vessels, and erosion of shoreline with additional damages to berthing facilities. Thus, in this study, the researchers have investigated the response of stem waves at the vertical breakwater near the entrance channel and applied numerical models, which are commonly used for the analysis of wave response at the harbor design. The basic equation composing models here adopted both the linear parabolic approximation adding the nonlinear dispersion relationship and nonlinear parabolic approximation adding a linear dispersion relationship. To analyze the applicability of both models, the research compared the numerical results with the existing hydraulic model results. The gap of serial breakwaters and aligned angles caused more complicated stem wave generation and secondary stem wave was found through the breakwater gap. Those analyzed results should be applied to ship handling simulation studies at the approaching channels, along with the mooring test.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.26 no.1
• /
• pp.1-7
• /
• 2013

Structural design and analysis of a coiling arm unloading machine for submarine cable have been originally conducted in this study. Three-dimensional CAD modeling process is practically applied for the structural design in detail. Finite element method(FEM) and multi-body dynamics(MBD) analyses are also used to verify the safety and required motions of the designed coiling arm structure. The effective moving functions of the designed coiling arm with respect to rotational and radial motions are achieved by adopting bearing-roller mechanical parts and hydraulic system. Critical design loading conditions due to its self weight, carrying cables, offshore wind, and hydraulic system over operation conditions are considered for the present structural analyses. In addition, possible inclined ground conditions for the installation of the designed coiling arm are also considered to verify overturn stability. The present hydraulic type coiling arm system is originally designed and developed in this study. The developed coiling arm has been installed at a harbor, successfully tested its operational functions, and finished practical unloading mission of the submarine cable.