• 한국물환경학회지
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• 제31권4호
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• pp.428-435
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• 2015

This study was carried out to evaluate the performance of a inflow controller for the control of combined sewer overflows (CSOs). Because of the inflow controller could be adjusted manually by predicting the maximum amount of peak flow, the mechanical adjustment of this controller was higher than the existing fixed-type controller in field application. Standardizing the relationship between the flow and the clearance and angle of an inlet cover plate on the inflow conditions can selected to the optimum conditions for the on-site. It was concluded that BOD pollutant loading at the region in which inflow controller was installed had shown the removal efficiency rate of 42%.

• Environmental Engineering Research
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• 제10권2호
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• pp.62-70
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• 2005

Pollution loading of Combined Sewer Overflows (CSOs) is frequently over the capacity of a wastewater treatment plant (WWTP) receiving the water. The objectives of this study are to investigate water quality of CSOs in Anmyun-ueup, Tean province and to apply Storm Water Management Model to predict flow rate and water quality of the CSOs. The capacity of a local WWTP was also estimated according to rainfall duration and intensity. Eleven water quality parameters were analyzed to characterize overflows. SWMM model was applied to predict the flow rate and pollutant load of CSOs during rain event. Overall, profile of the flow and pollutant load predicted by the model well followed the observed data. Based on model prediction and observed data, CSOs frequently occurs in the study area, even with light precipitation or short rainfall duration. Model analysis also indicated that the local WWTP’s capacity was short to cover the CSOs.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.163-171
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• 2003

Most of existing beam-to-column connections are reinforced symmetrically because of reverse action cause by earthquake but in the weak-earthquake region like Korea connections reinforced asymmetrically can be used. Specially, the connections between CFT(Concrete Filled Tube) column and H-shape beam can be applied by simplified lower diaphragm. The tensile capacity of Combined Cross Diaphragm for upper reinforcing was tested by simple tension test and four types for lower reinforcing; Combined Cross, None, Horizontal T-bar and Vertical Plate were tested by ANSI/AISC SSPEC 2002 loading program. Horizontal T-bar and stud bolts in vertical flat bar transmit tensile stress from bottom flange of beam to filled concrete. All test specimens were satisfied 0.01 radian of inelastic rotational requirement in ordinary moment frame of AISC seismic provision. As the results of parametric studies, simplified lower diaphragms demonstrated an outstanding strength, stiffness and plastic deformation capacity to use sufficient seismic performance in the field.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권1호
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• pp.39-59
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• 2014

Nowadays aluminum stiffened plates are one of the major constituents of the marine structures, especially high-speed vessels. On one hand, these structures are subject to various forms of loading in the harsh sea environment, like hydrostatic lateral pressures and in-plane compression. On the other hand, fusion welding is often used to assemble those panels. The common marine aluminum alloys in the both 5,000 and 6,000 series, however, lose a remarkable portion of their load carrying capacity due to welding. This paper presents the results of sophisticated finite-element investigations considering both geometrical and mechanical imperfections. The tested models were those proposed by the ultimate strength committee of $15^{th}$ ISSC. The presented data illuminates the effects of welding on the strength of aluminum plates under above-mentioned load conditions.

• Steel and Composite Structures
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• 제32권3호
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• pp.313-323
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• 2019

Ratcheting boundary is firstly determined by experiment, elastic-plastic finite element analysis combined with C-TDF and linear matching method, which is compared with ASME/KTA and RCC-MR. Moreover, based on elastic modulus adjustment procedure, a novel method is proposed to predict the ratcheting boundary for a pressurized pipe subjected to constant internal pressure and cyclic bending loading. Comparison of ratcheting boundary of elbow pipe determined by the proposed method, elastic-plastic finite element analysis combined with C-TDF and linear matching method, which indicates that the predicted results of the proposed method are in well agreement with those of linear matching method.

• Steel and Composite Structures
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• 제33권2호
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• pp.245-259
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• 2019

The present study aims to investigate the ultimate strength and geometric nonlinear behavior of composite plates containing initial imperfection subjected to combined end-shortening strain and lateral pressure loading by using a semi-analytical method. In this study, the first order shear deformation plate theory is considered with the assumption of large deflections. Regarding in-plane boundary conditions, two adjacent edges of the laminates are completely held while the two others can move straightly. The formulations are based on the concept of the principle of minimum potential energy and Newton-Raphson technique is employed to solve the nonlinear set of algebraic equations. In addition, Hashin failure criteria are selected to predict the failures. Further, two distinct models are assumed to reduce the mechanical properties of the failure location, complete ply degradation model, and ply region degradation model. Degrading the material properties is assumed to be instantaneous. Finally, laminates having a wide range of thicknesses and initial geometric imperfections with different intensities of pressure load are analyzed and discuss how the ultimate strength of the plates changes.

• 대한기계학회논문집A
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• 제27권7호
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• pp.1170-1178
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• 2003

This paper provides approximate J estimates for off-centred, circumferential through-wall cracks in cylinders under bending and under combined tension and bending. The proposed method is based on the reference stress approach, where the dependence of elastic and plastic influence functions of J on the cylinder/crack geometry, the off-centred angle and strain hardening is minimised through the use of a proper normalising load. Based on published limited FE results for off-centred, circumferential through-wall cracks under bending, such normalising load is found, based on which the reference stress based J estimates are proposed for more general cases, such as for a different cylinder geometry and for combined loading. Comparison of the estimated J with extensive FE J results shows overall good agreements for different crack/cylinder geometries and for combined tension and bending, which provides sufficient confidence in the use of the proposed method to fracture mechanics analyses of off-centred circumferential cracks. Furthermore, the proposed method is simple to use, giving significant merits in practice.

• 한국전산구조공학회논문집
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• 제24권1호
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• pp.17-22
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• 2011

본 논문에서는 Tsai-Hill기준을 변형하여 조합하중을 받는 이방성재료의 강도를 정확히 예측할 수 있는 새로운 파손기준을 제안하였다. 이 기준의 유효성은 조합하중을 받고 있는 Kraft 판지에 대한 실험결과와 비교하여 나타내었다. 재료축 방향의 전단응력이 주어진 경우, Tsai-Hill기준은 매우 보수적인 결과를 보여주고 있으나, 본 해석에서 제안한 기준은 실험 결과와 잘 일치하고 있다. 또한 Tan-Cheng기준과 비교하여 강도를 더욱 단순하게 해석할 수 있는 능력을 갖고 있다.

• Geomechanics and Engineering
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• 제7권3호
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• pp.317-333
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• 2014

The study of the mechanical behavior of rockfill materials under three-dimensional loading conditions is a current research focus area. This paper presents a microscale numerical study of rockfill deformation and strength characteristics using the Combined Finite-Discrete Element Method (FDEM). Two features unique to this study are the consideration of irregular particle shapes and particle crushability. A polydisperse assembly of irregular polyhedra was prepared to reproduce the mechanical behavior of rockfill materials subjected to axial compression at a constant mean stress for a range of intermediate principal stress ratios in the interval [0, 1]. The simulation results, including the stress-strain characteristics, relationship between principal strains, and principal deviator strains are discussed. The stress-dilatancy behavior is described using a linear dilatancy equation with its material constants varying with the intermediate principal stress ratio. The failure surface in the principal stress space and its traces in the deviatoric and meridian plane are also presented. The modified Lade-Duncan criterion most closely describes the stress points at failure.

• Steel and Composite Structures
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• 제26권4호
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• pp.407-420
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• 2018

Experiments were performed to explore the hysteretic performance of steel reinforced concrete (SRC) cross-shaped columns. Nine specimens were designed and tested under the combined action of compression, flexure, shear and torsion. Torsion-bending ratio (i.e., 0, 0.14, 0.21) and steel forms (i.e., Solid - web steel, T - shaped steel, Channel steel) were considered in the test. Both failure processes and modes were obtained during the whole loading procedure. Based on experimental data, seismic indexes, such as bearing capacity, ductility and energy dissipation were investigated in detail. Experimental results suggest that depending on the torsion-bending ratio, failure modes of SRC cross-shaped columns are bending failure, flexure-torsion failure and torsion-shear failure. Shear - displacement hysteretic loops are fuller than torque - twist angle hysteretic curves. SRC cross-shaped columns exhibit good ductility and deformation capacity. In the range of test parameters, the existence of torque does not reduce the shear force but it reduces the displacement and bending energy dissipation capacity. What is more, the bending energy dissipation capacity increases with the rising of displacement level, while the torsion energy dissipation capacity decreases.