• Title/Summary/Keyword: Mass Loading

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Design of Residual Treatment Process with Filter Backwash Recycle System (역세척수 회수시스템이 포함된 배출수처리공정의 설계)

  • Bae, Byung-Uk;Choi, Kyung-Hwan
    • Journal of Korean Society on Water Environment
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    • v.28 no.1
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    • pp.109-114
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    • 2012
  • In this study, both sedimentation and thickening experiments were conducted for residuals produced from an advanced water treatment plant for more accurate and practical design of residual treatment train. In order to design a backwashed residual sedimentation basin (SRSB) in the filter backwash water recycle system, two kinds of backwash waters, one from sand filter (SFBW) and the other from GAC adsorption bed (GACBW), were separately collected and their surface loading rate measured. In addition, in order to design a gravity thickener, batch thickening tests were conducted for concentrated residuals taken from sedimentation basin and their limiting solid flux ($SF_{L}$) measured. From the experimental results and consideration of the seasonal characteristics of the residual, surface loading rate of $70m^{3}/m^{2}{\cdot}d$ was proposed as a design parameter for SRSB and solid loading rate of 20 kg $TS/m^{2}{\cdot}d$ was proposed as a design parameter for gravity thickeners. Finally, the material mass-balance was made for the design of each unit process in the residual treatment train.

Fiber reinforced concrete L-beams under combined loading

  • Ibraheem, Omer Farouk;Abu Bakar, B.H.;Johari, I.
    • Computers and Concrete
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    • v.14 no.1
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    • pp.1-18
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    • 2014
  • The addition of steel fibers in concrete mixture is recognized as a non-conventional mass reinforcement scheme that improves the torsional, flexural, and shear behavior of structural members. However, the analysis of fiber reinforced concrete beams under combined torsion, bending, and shear is limited because of the complicated nature of the problem. Therefore, nonlinear 3D finite element analysis was conducted using the "ANSYS CivilFEM" program to investigate the behavior of fiber reinforced concrete L-beams. These beams were tested at different reinforcement schemes and loading conditions. The reinforcement case parameters were set as follows: reinforced with longitudinal reinforcement only and reinforced with steel bars and stirrups. All beams were tested under two different combined loading conditions, namely, torsion-to-shear ratio (T/V) = 545 mm (high eccentricity) and T/V = 145 mm (low eccentricity). Eight intermediate L-beams were constructed and tested in a laboratory under combined torsion, bending, and shear to validate the finite element model. Comparisons with the experimental data reveal that the program can accurately predict the behavior of L-beams under different reinforcement cases and combined loading ratios. The ANSYS model accurately predicted the loads and deformations for various types of reinforcements in L-beams and captured the concrete strains of these beams.

Experimental Study on Active Control of Building Structures by Feedback Variables (피드백 변화에 따른 건물의 능동제어 실험)

  • 민경원
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 1998.10a
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    • pp.286-294
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    • 1998
  • This paper presents an experimental study on the performance of the active damper device by feedback variables. The damper is a mass-typed active device, which exerts the inertia control force on the building by AC servo motor. The control performance is experimentally analyzed considering the building response and the control force. It is found that the building response is greatly reduced by mass-typed device under the resonant and earthquake loading. Also, the experimental results show that the velocity feedback reduces the building responses with the smallest amount of control force than any other feedback variables.

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Performance validation and application of a mixed force-displacement loading strategy for bi-directional hybrid simulation

  • Wang, Zhen;Tan, Qiyang;Shi, Pengfei;Yang, Ge;Zhu, Siyu;Xu, Guoshan;Wu, Bin;Sun, Jianyun
    • Smart Structures and Systems
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    • v.26 no.3
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    • pp.373-390
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    • 2020
  • Hybrid simulation (HS) is a versatile tool for structural performance evaluation under dynamic loads. Although real structural responses are often multiple-directional owing to an eccentric mass/stiffness of the structure and/or excitations not along structural major axes, few HS in this field takes into account structural responses in multiple directions. Multi-directional loading is more challenging than uni-directional loading as there is a nonlinear transformation between actuator and specimen coordinate systems, increasing the difficulty of suppressing loading error. Moreover, redundant actuators may exist in multi-directional hybrid simulations of large-scale structures, which requires the loading strategy to contain ineffective loading of multiple actuators. To address these issues, lately a new strategy was conceived for accurate reproduction of desired displacements in bi-directional hybrid simulations (BHS), which is characterized in two features, i.e., iterative displacement command updating based on the Jacobian matrix considering nonlinear geometric relationships, and force-based control for compensating ineffective forces of redundant actuators. This paper performs performance validation and application of this new mixed loading strategy. In particular, virtual BHS considering linear and nonlinear specimen models, and the diversity of actuator properties were carried out. A validation test was implemented with a steel frame specimen. A real application of this strategy to BHS on a full-scale 2-story frame specimen was performed. Studies showed that this strategy exhibited excellent tracking performance for the measured displacements of the control point and remarkable compensation for ineffective forces of the redundant actuator. This strategy was demonstrated to be capable of accurately and effectively reproducing the desired displacements in large-scale BHS.

Variations of Estimated Pollutant Loading from Rural Streams with Sampling Intervals (채수빈도를 고려한 소하천의 수질오염부하량 특성 연구)

  • 강문성;박승우;윤광식
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 1998.10a
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    • pp.552-557
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    • 1998
  • Sampling schemes are intended for use in situations where stream-flow data are collected regularly, but concentration data are collected during only a limited number of time periods. Estimating water pollutant loading considering sampling intervals is presented, and for illustrative purposes the criterion is applied to the sampling station HS#3 of the Balan-reservoir watershed which is located at the southwest of Suwon. The stratification is employed uniformly for all sampling strategies in that the strata boundaries are defined using the actual distribution of flow values and the selected nonexceedence probabilities to minimize inaccuracy. Ratio estimator for SS, T-N, and T-P were used in order to calculate the water pollutant loading. A sampling scheme incorporating stratified sampling with real-time of the sampling characteristics is found to give the appropriate estimate of the mass load.

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Development of Falling Weight Deflectometer for Evaluation of Layer Properties of Flexible Pavement (도로포장 구조체의 물성 추정을 위한 FWD의 설계 및 제작)

  • 황성호;손웅희;최경락
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.3
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    • pp.124-130
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    • 2003
  • Many structural evaluation procedures of road and airfield pavements use the Falling Weight Deflectometer (FWD) as a critical element of non-destructive deflection testing. FWD is a trailer mounted device that provides accurate data on pavement response to dynamic wheel loads. A dynamic load is generated by dropping a mass from a variable height onto a loading plate. The magnitude of the load and the pavement deflection are measured by a load celt and geophones. And database concerning pavement damage should be enhanced to analyze loss of thickness asphalt layer caused from the plastic deformation of pavement structure, such as cracking or rutting. The prototype FWD is developed, which consists of chassis system, hydraulic loading system, data acquisition and analysis system. This system subsequently merged to from automation management system and is then validated and updated to produce a working FWD which can actually be used in the field.

Numerical Analysis on the Die Pad/Epoxy Molding Compound(EMC) Interface Delamination in Plastic Packages under Thermal and Vapor Pressure Loadings

  • Jin Yu
    • Journal of the Microelectronics and Packaging Society
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    • v.5 no.2
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    • pp.37-48
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    • 1998
  • The popcorn cracking phenomena in plastic IC packages during reflow soldering are investigated by considering the heat transfer and moisture diffusion through the epoxy molding compound(EMC) along with the mechanics of interface delamination. Heat transfer and moisture diffusion through EMC under die pad are analyzed by finite difference method (FDM)during the pre-conditioning and subsequent reflow soldiering pro-cess and the amounts of moisture mass and vapor pressure at delaminated die pad/ EMC interface are calculated as a function of the reflow soldering time. The energy release rate stress intensity factor and phase angle were obtained under various loading conditions which are thermal crack face vapor pressure and mixed loadings. It was shown that thermal loading was the main driving force for the crack propagation for small crack lengths but vapor pressure loading played more significant role as crack grew.

Stress state around cylindrical cavities in transversally isotropic rock mass

  • Lukic, Dragan C.;Prokic, Aleksandar D.;Brcic, Stanko V.
    • Geomechanics and Engineering
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    • v.6 no.3
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    • pp.213-233
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    • 2014
  • The present paper is dealing with the investigation of the stress field around the infinitely long cylindrical cavity, of a circular cross section, contained in the transversally isotropic elastic continuum. Investigation is based upon the determination of the stress function that satisfies the biharmonic equation, for the given boundary conditions and for rotationaly symmetric loading. The solution of the partial differential equation of the problem is given in the form of infinite series of Bessel's functions. Determination of the stress-strain field around cavities is a common requirement for estimation of safety of underground rock excavations.

A Study on the Characteristics of Bearing Capacity for SIP Piles constructed on Rock Mass (암반에 근입된 SIP 말뚝의 지지력 특성에 관한 연구)

  • Kim, Tae-Hwoon;Park, Jun-Hong;Lee, Song
    • Proceedings of the KSR Conference
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    • 2002.05a
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    • pp.295-300
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    • 2002
  • In this research problems of recent design methods and their improvement for SIP in domestic areas were studied by using the characteristics of load-settlement curves and bearing capacity from field loading tests. Elastic and plastic settlement for total settlement in each loading step conducted domestic areas had a tendency. From these tendency and bearing capacity determined by loading tests we can ascertain that empirical chart can be assistant tool in SIP design. It showes that SIP design using N-value in domestic area with soil condition of grarute type results in very conservative bearing capacity, to be opposed in soil with unprofitable geological condition the design can be insecure. Also, we can ascertain that Meyerhof's bearing capacity used modified N-value on tip part of pile is more applicable than recent design method where tip bearing capacity is 20NAp N-value limited to 50. These results show that modified design method can he more economic than before because of using pile's bearing capacity to tolerable load of pile material.

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The dynamic response of the FGM coated half-plane with hysteretic damping under time harmonic loading

  • Xiao-Min Wang;Liao-Liang Ke;Yue-Sheng Wang
    • Structural Engineering and Mechanics
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    • v.87 no.1
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    • pp.95-106
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    • 2023
  • This paper investigates the dynamic response of a functionally graded material (FGM) coated half-plane excited by distributed time harmonic loading. Three types of typical distributed surface loads, including uniform load, Hertz load, and square-root singular load, are considered. The mass density and elastic modulus of the FGM coating are supposed to be described by the exponential function. The material damping is modelled by a linearly hysteretic damping which is expressed by a complex modulus in the time harmonic motion. Using Fourier integral transform technique and numerical integral method, the effects of the excitation frequency, gradient index, damping, and load type on the dynamic stresses and displacements are discussed.