• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.45-46
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• 2006

Experimental and numerical analysis on the heat transfer behaviors and the associated frictional loss in a rectangular channel with two inclined perforated baffles($\;5^{\circ}$) mounted on the bottom plate has been systematically performed. The parametric effects of perforated baffles (3, 6, 9 holes) and flow Reynolds number on heat transfer characteristics of the heated target surface are explored. A combination of two baffles of same overall size was considered and the flow Reynolds number for this study is varied between 28,900 and 61,800. Comparisons of the experimental data with the numerical results by commercial code CFX 5.7 are made. As for the investigation of heat transfer behaviors on local Nusselt number with the two baffles installed at $x/D_h=0.8\;and\;x/D_h=8.0$, it is evident that there exist an optimum perforation density to maximize heat transfer coefficients; i.e., the maximum Nusselt number decreases with increasing number of holes.

• Journal of Hydrogen and New Energy
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• v.22 no.6
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• pp.878-883
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• 2011

Effect of flow uniformity on the reaction characteristics of a catalytic combustor for high temperature fuel cell system has been experimentally investigated in the present study. One of the most important factor in designing catalytic combustion is to avoid hot spot in catalysts. In this regard, it is very important to secure flow uniformity of combustor inlet. A couple of perforated plates were applied at the front of catalyst region as flow uniformity device with minimal pressure drop. Results show that the velocity and temperature profile became more uniform when applying the flow uniformity device. CO and $CH_4$ emissions at the combustor exit were decreased and the average exit temperature was slightly increased with the flow uniformity device.

• Structural Engineering and Mechanics
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• v.61 no.2
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• pp.255-266
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• 2017

In this study, self-supporting roofing elements especially convenient for large-span structures such as stadium, airport terminal, mall, coliseum, etc. were examined with respect to critical buckling load. These elements were assumed as laminated composite plates and, variation of free-edge forms, cutout types and lamination configurations were used as design parameters. Based on the architectural feature and structural requirements, the effects of curvilinear free-edge form on critical buckling load were focused on in this research. Within this scope, 14 types of lamination configuration were specified according to various orientation angle, number and thickness of plies with a constant value of total plate thickness. Besides that, 6 different types of cutout and 3 different free-edge forms were determined. By combining all these parameters 294 different critical buckling load analyses were performed by using ANSYS Mechanical software based on finite element method. Effects of those parameters on critical buckling load were evaluated referring to the obtained results. According to the results presented here, it may be concluded that lamination conditions have more significant influence on the critical buckling load values than the other parameters. On the other hand, it is perceived that curvilinear free-edge forms explicitly undergo changings depending on lamination conditions. For future work, existence of delamination might be considered and progression of the defect could be investigated by using non-linear analysis.

• Environmental Engineering Research
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• v.19 no.2
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• pp.151-155
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• 2014

This study compares the effects of flow on oil and suspended solids removal efficiencies in circular enhanced gravity plate separator equipped with coalescence medium. Coalescence medium acts to capture rising oil droplets and settling solid particles and assist in the coalescence of oil and coagulation of solid. The circular separator uses an upflow center-feed perforated-pipe distributor as the inlet. The co-current flow is achieved using 4 increasing sizes of frustum, whereas cross flow uses inclined coalescence plates running along the radius of the separator. The different arrangement gave the cross flow separator a higher coalescence plan area per operational volume, minimal and constant travelling distance for the oil droplets and particles, lower retention time, and higher operational flowrate. The cross flow separator exhibited 6.04% and 13.16% higher oil and total suspended solids removal efficiencies as compared to co-current flow.

• Computers and Concrete
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• v.7 no.2
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• pp.103-118
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• 2010

Penetration of a fragment-like projectile into Fiber Reinforced Concrete (FRC) was simulated using finite element (FE) and particle formulations. Extreme deformations and failure of the material during the penetration event were modeled with multiple approaches to evaluate how well each represented the actual physics of the penetration process and compared to experimental data. A Fragment Simulating Projectile(FSP) normally impacting a flat, square plate of FRC was modeled using two target thicknesses to examine the different levels of damage. The thinner plate was perforated by the FSP, while the thicker plate captured the FSP and only allowed penetration part way through the thickness. Full three dimensional simulations were performed, so the capability was present for non-symmetric FRC behavior and possible projectile rotation in all directions. These calculations assessed the ability of the finite element and particle formulations to calculate penetration response while assessing criteria necessary to perform the computations. The numerical code EPIC contains the element and particle formulations, as well as the explicit methodology and constitutive models, needed to perform these simulations.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.4
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• pp.427-436
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• 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 the Korean Society of Manufacturing Process Engineers
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• v.20 no.1
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• pp.80-87
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• 2021

Most container ships are currently being constructed as Ultra-Large Container Ships. Hence, the equipment of the ships is also becoming relatively large. In particular, propellers, rudders, and rudder stocks are large in the stern structure, and in relation, efficient design of the hull structures to safely secure these parts is important. The bottom shell plate surface of a stern skeg is a perforated plate from which the rudder stock penetrates, so it is an important component for the stern structure. In this paper, to determine the critical buckling of the shell plate, an interaction curve equation for the two-axis compression of the shell plate was derived using the maximum value of the static structural stress multiplier in a load multiplier mode. This equation predicts the timing of the buckling occurrence. By analyzing this interaction curve equation, the buckling behavior of the plates subjected to a combination load was determined and the usefulness of applying it to ship building was investigated.

• The Journal of the Acoustical Society of Korea
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• v.40 no.1
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• pp.55-63
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• 2021

In this study, a numerical methodology is proposed for evaluating valve flow noise in a pipe conveying high pressure gas, and the effects of perforated plates on reduction of such valve flow noise are quantitatively analyzed. First, high-accurate unsteady compressible Large Eddy Simulation techniques are utilized to predict flow and flow noise by a valve in a high-pressure pipe. The validity of the numerical result is confirmed by comparing the predicted wall pressure spectrum with the measured one. Next, the acoustic power of downstream-propagating acoustic waves due to the valve flow is analyzed using an acoustic power formula for acoustic waves propagating on mean flow in a pipe. Based on the analysis results, perforated plates are designed and installed downstream of the valve to suppress the valve flow noise and the acoustic power of downstream-going acoustic waves is predicted by using the same numerical procedure. The reduction by 9.5 dB is confirmed by comparing the predicted result with that of the existing system. Based on these results, the current numerical methodology is expected to be used to reduce valve flow noise in an existing system as well as in a design stage.

• Earthquakes and Structures
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• v.22 no.6
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• pp.539-548
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• 2022

Steel plate shear walls (SPSWs) are one of the most important and widely used lateral load-bearing systems. The reason for this is easier execution than reinforced concrete (RC) shear walls, faster construction time, and lower final weight of the structure. However, the main drawback of SPSWs is premature buckling in low drift ratios, which affects the energy absorption capacity and global performance of the system. To address this problem, two groups of SPSWs under cyclic loading were investigated using the finite element method (FEM). In the first group, several series of circular rings have been used and in the second group, a new type of SPSW with concentric circular rings (CCRs) has been introduced. Numerous parameters include in yield stress of steel plate wall materials, steel panel thickness, and ring width were considered in nonlinear static analysis. At first, a three-dimensional (3D) numerical model was validated using three sets of laboratory SPSWs and the difference in results between numerical models and experimental specimens was less than 5% in all cases. The results of numerical models revealed that the full SPSW undergoes shear buckling at a drift ratio of 0.2% and its hysteresis behavior has a pinching in the middle part of load-drift ratio curve. Whereas, in the two categories of proposed SPSWs, the hysteresis behavior is complete and stable, and in most cases no capacity degradation of up to 6% drift ratio has been observed. Also, in most numerical models, the tangential stiffness remains almost constant in each cycle. Finally, for the innovative SPSW, a relationship was suggested to determine the shear capacity of the proposed steel wall relative to the wall slenderness coefficient.

• Steel and Composite Structures
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• v.49 no.2
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• pp.215-230
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• 2023

Cable-girder anchorage joint is the critical part of cable-supported bridges. Tensile-plate anchorage (TPA) is one of the most commonly used types of cable-girder anchorage joints in steel girder cable-supported bridges. In recent years, it has been proposed by bridge designers to apply TPA to concrete girder cable-supported bridges to form composite cable-girder anchorage joint (CCGAJ). In this paper, the mechanical performance of CCGAJ under tensile force is studied through experimental and numerical analyses. Firstly, the effects of the external prestressing (EP) and the bearing plate (BP) on the mechanical performance of CCGAJ were investigated through three tests. Then, finite element model was established for parametrical study, and was verified by the experimental results. Then, the effects of shear connector forms, EP, BP, vertical rebar rate, and perforated rebar rate on the tensile capacity of CCGAJ were investigated through numerical analyses. The results show that the tensile capacity of CCGAJ depends on the first row of PR. The failure mode of CCGAJ using headed stud connectors is to form a shear failure surface at the end of the studs while the failure mode using PBLs is similar to the bending of a deep girder. Finally, based on the strut-and-tie model (STM), a calculation method for CCGAJ tensile capacity was proposed, which has a high accuracy and can be used to calculate the tensile capacity of CCGAJ.