• Geomechanics and Engineering
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• v.19 no.3
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• pp.255-268
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• 2019

Taking top-coal caving mining face (TCCMF) as research object, this paper considers the combination of top-coal and immediate roof as cushion layer to build the solution model of support resistance based on the theory of elastic foundation beam. Meanwhile, the physical and mechanical properties of coal-rock combination influencing on strata behaviors is explored. The results illustrate that the subsidence of main roof in coal wall increases and the first weighting interval decreases with the increase of top-coal and immediate roof thicknesses as well as the decrease of top-coal and immediate roof elastic modulus. Moreover, the overlying strata reflecting on support has negative and positive relationship with top-coal thickness and immediate roof thickness, respectively. However, elastic modulus has limit influence on the dead weight of top-coal and immediate roof. As a result, it has similar roles on the increase of total support resistance and overlying strata reflecting on support in the limit range of roof control distance. In view of sensitive analysis causing the change of total support resistance, it can be regards as the rank of three components as immediate roof weight > overlying strata reflecting on support > top coal weight. Finally, combined with the monitoring data of support resistance in Qingdong 828, the validity of support resistance determined based on elastic foundation beam is demonstrated, and this method can be recommended to adopt for support type selecting in TCCMF.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.3
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• pp.89-97
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• 2002

In this study, the effect of $\alpha$-phase morphology on the dynamic deformation behavior at ultra high strain rate was investigated by EBW(Explosive Bridge Wire) test. All of tests and analyses were conducted on three typical microstructures of Ti-6Al-4V alloy, i.e. equiaxed, widmanstatten and bimodal microstructures. The spall strength and HEL(Hugoniot Elastic Limit) of the specimens that have the thickness of 2mm and 4mm were highest with the bimodal microstructure. These results were similar with previous study which was performed by dynamic torsion test(Kolsky torsion test).

• International Journal of High-Rise Buildings
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• v.1 no.1
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• pp.1-13
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• 2012

The importance of appropriate use of damping evaluation techniques and points to note for accurate evaluation of damping are first discussed. Then, the variation of damping ratio with amplitude is discussed, especially in the amplitude range relevant to wind-resistant design of buildings, i.e. within the elastic limit. The general belief is that damping increases with amplitude, but it is emphasized that there is no evidence of increasing damping ratio in the very high amplitude range within the elastic limit of main frames, unless there is damage to secondary members or architectural finishings. The damping ratio rather decreases with amplitude from a certain tip drift ratio defined as "critical tip drift ratio," after all friction surfaces between primary/structural and secondary/non-structural members have been mobilized.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.773-776
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• 1997

This paper presents an investigation of the energy absorption of composite laminates during ballistic impact. Three components are responsible for the absorption of energy-the tensile failure of fiber, the elastic deformation of the composite, the delamination of composite laminates. The ballistic limit, V/sub 0/, of the laminates is determined using a previous model implemented to determine the energy absorption of the three components listed above. The size of the deformed zone during impact was estimated by an approximate solution for impacts on plates. The carbon/epoxy plates were examined for this research.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.17 no.32
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• pp.73-79
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• 1994

본 연구는 관리한계설정을 위한 새로운 방법을 제시한다. 일반적 관리한계는 중심선(Central Line)과 표준편차(Standard Deviation)에 기인한다. 그러나 본 연구에서는 제품수명주기(PLC)의 각 단계상 발생되는 손익분기점(Break-even Point)과 한계이익곡선 특성을 통하여 탄력적 관리한계(Elastic Control Limit : ECL)를 구축하고자 하였다. 탄력적 관리한계와 한계이익곡선의 관계에서 중심선은 최대이익, $3{sigma}$한계는 최대이익점과 가장 근접해 있는 (상위/하위)손익분기점까지의 거리로 파악할 수 있다. 그리고 총 변동은 ｛상위손익분기점(UBEP) - 하위손익분기점(LBEP)｝으로 고려할 수 있다. 전개 과정으로서는 1. 각 제품별 수명주기(PLC)를 각 단계별로 구분한다. 2. 각 단계별 총이익곡선(TRC)과 총비용곡선(TCC)을 구한다. 3. 한계이익곡선상의 최대이익지점을 구한다. 이러한 연구는 제품성장단계별 평균과 분산의 변동을 동시에 고려하여 탄력적 관리가 가능하다는 장점이 있다. 나아가 마케팅과 소비자 행동의 분석으로 확대될 수 있다.

• Composites Research
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• v.13 no.5
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• pp.37-43
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• 2000

In this paper an analytical investigation pertaining to the elastic shear buckling behavior of transversely stiffened orthotropic plate under in-plane shear forces is presented. All edges of plate are assumed to be simply supported and the evenly placed stiffener is considered as a beam element neglecting its torsional rigidity. For the solution of the problem Rayleigh-Ritz method is employed. Using the derived equation, the limit of buckling stress of transversely stiffened plate is suggested as a graphical form. Based on the limit of buckling stress of stiffened plate, graphical form of results for finding the required stiffener rigidity is presented when one and two stiffeners are located, respectively.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.435-442
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• 2002

Fluid Confirmation Tests(FCT) on 1500 ground Anchors install in weathered rock were carried out to investigate upper and lower limit of elastic elongation, frictional resistant of fixed anchor body, mobilized angle between anchor body and soil. All the measured data were analysed and compared with theoretical equations. The frictional angles of diaphragm wall and anchorage system in weathered rock showed nonlinear curve between upper and lower limit of standard elongation. The FCT results indicated that the frictional resistant angles increased with higher values of surcharge load. The quality assurance on the fixed anchor location was investigated by means of measuring elastic elongation during the FCT, and comparing these with theoretical design length, the quality of anchors in this particular site found to be above average standard. The results of this research works with provide valuable guide line on quality assurance of anchors system as well as resonable prediction of friction resistance between the fixed anchor body and the weathered rock.

• Journal of the Korean Society of Safety
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• v.8 no.1
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• pp.47-53
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• 1993

Residual Deformation Analysis(RDA) is a new method for ratings of the continuous bridges. The RDA makes it possible to expand the inelastic steel girder bridge design method set forth in the American Association of State Highway Officals'(AASHTO) Guide Specifications for Alternate Load Factor Design Procedures for Steel Beam Bridges Using Braced Compact Sections(1986) into an inelastic rating method. It is a method to assess the residual moments and deformations that are set up in a beam that has been loaded into the post-elastic range This method combines classical elastic conjugate beam theory with linear moment-rotation relationships for midspan inelastic positive moment. The limit state is inelastic serviceability limit. which is defined as the ratio of the span to midspan inelastic deflection(C=L/D).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.5 s.248
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• pp.568-575
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• 2006

The present paper provides plastic limit load solutions of axial and circumferential through-wall cracked pipes based on detailed three-dimensional (3-D) finite element (FE) limit analysis using elastic-perfectly-plastic behavior. As a loading condition, axial tension, global bending moment, internal pressure, combined tension and bending and combined internal pressure and bending are considered for circumferential through-wall cracked pipes, while only internal pressure is considered for axial through-wall cracked pipes. Especially, more emphasis is given for through-wall cracked pipes subject to combined loading. Comparisons with existing solutions show a large discrepancy in short through-wall crack (both axial and circumferential) for internal pressure. In the case of combined loading, the FE limit analyses results show thickness effect on limit load solutions. Furthermore, the plastic limit load solution for circumferential through-wall cracked pipes under bending is applied to derive plastic $\eta\;and\;{\gamma}$-factor of testing circumferential through-wall cracked pipes to estimate fracture toughness. Being based on detailed 3-D FE limit analysis, the present solutions are believed to be meaningful fur structural integrity assessment of through-wall cracked pipes.

• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.535-541
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• 2020

A conventional elastic material replacement and performance evaluation are very complicated and time-consuming, and it is difficult to know when to replace the elastic material in advance. By comparing with the product limit and the functional limit, the necessity of elastic material replacement and the improvement of track support stiffness according to replacement can be immediately demonstrated based on experimental data. Using an evaluation system of track support stiffness, the performance evaluation data for elastic materials obtained through field tests using software for track support stiffness is integrated and managed on the administrator's computer. Therefore, the replacement plan is established and maintenance history is managed by identifying the replacement time and location of elastic materials. It is possible to evaluate the performance and condition of the elastic material at the various points during the working time of the track inspection and the track performance (track support stiffness) and durability of the elastic material (aging level, spring stiffness variation rate, etc.) at the operation condition. The elastic material could be replaced timely, and the deterioration of the elastic material can be continuously monitored.