• 비파괴검사학회지
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• 제14권1호
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• pp.16-22
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• 1994

일반적으로 구름 베어링 시스템에 비해 발전용 터어빈이나 내연기관 엔진과 같은 저어널 베어링을 가진 시스템은 상대적으로 대형 설비이거나 더 가혹한 운전조건에서 가동되는 경우가 많다. 이런 회전기계류에서의 베어링의 파손은 설비의 운전 중단 및 관련 설비의 파손까지도 초래할 수 있게 된다. 따라서 이로 인한 보수에 소비되는 시간 및 경제적인 손실등을 피하기 위해서는 저어널 베어링의 조기파손 감지의,역할은 매우 중요하게 된다. 본 연구에서는 음향방출 기술을 이용하여 베어링에서 발생할 수 있는 파손의 조기검출을 위해 실험실용으로 직접 제작한 저어널 베어링 시스템을 이용하여 여러 형태의 비정상 조건을 만들어 가며 실험을 행하였다. 베어링 손상 및 피로의 주 요인으로서는 윤활유 부족, 윤활층에의 이물질의 혼입, 조립 불량 등이 대표적인 원인으로서 알려져 있으며 이에 근거하여 실험 조건을 윤활유에의 이물질 혼입, 윤활유 부족, 그리고 축과 베어링간의 금속간 접촉등의 인위적인 형태로 구성하여 실험하였다. 그 결과로서 음향방출 기술이 저어널 베어링의 조기파손 감지에 매우 효과적인 도구라는 것을 입증하였다.

• 한국지진공학회논문집
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• 제14권6호
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• pp.45-53
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• 2010

지진 시 낙교는 교량의 기능을 상실하는 가장 심각한 피해의 하나로서 반드시 피해야 한다. 교량 받침의 파괴로 인한 낙교를 방지하기 위한 방법의 하나로서 국내에서는 받침보호장치가 많이 사용되고 있다. 교량 받침부의 옆의 빈 공간에 설치되어 상부구조로부터 전달되는 지진하중을 부담하여 받침의 파괴를 방지한다. 이러한 받침보호장치가 충분한 내진성능을 발휘하기 위해서는 받침보호장치 본체뿐만 아니라 이를 교량에 고정시키는 앵커부의 강도도 함께 확보되어야 한다. 국내에서는 이들 앵커부의 설계 방법이 확립되지 않아서 받침보호장치의 공급업체가 제공하는 설계도에 따라 시공되어 왔다. 이에 본 연구에서는 베드블록의 높이가 다른 받침보호장치를 대상으로 하여 앵커부의 성능을 실험을 통하여 확인하였고 내진성능을 확보하기 적절한 설계법을 제시하였다.

• Tribology and Lubricants
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• 제25권5호
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• pp.324-329
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• 2009

In this study a complex design fitness analysis of journal bearings is carried out for the LPLi rotary-vane fuel pump application, as an external and horizontal installation, in LPG vehicles. Bearings considered in the analyses are plain and 3-axial groove journal bearings. Upon reflecting the fact that the primary failure mode of bearings in the application is a premature friction and wear failure of bearing metal due to a very low viscosity of liquid fuel LPG as a bearing lubricant, the performance factors of bearings used in an evaluation process of design fitness are a load carrying capacity and vibration suppression ability relative to a rated speed. At this time the design variables of bearings are a radial clearance and length. Results show that, in terms of both of the load carrying capacity and vibration suppression ability, the plain journal bearings are superior to the 3-axial groove journal bearings and among the plain bearings the smaller the bearing clearance (5>10>$15\;{\mu}m$) is and the longer the bearing length (6<8<10<12<14 mm) is, the better the bearing performance is.

• Steel and Composite Structures
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• 제22권2호
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• pp.217-234
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• 2016

In order to investigate mechanical properties and load-bearing capacity of T-shaped Concrete-Filled Square Steel Tubular (TCFST) composite columns under eccentric axial load, three T-shaped composite columns were tested under eccentric compression. Experimental results show that failure mode of the columns under eccentric compression was bending buckling of the whole specimen, and mono column performs flexural buckling. Specimens behaved good ductility and load-bearing capacity. Nonlinear finite element analysis was also employed in this investigation. The failure mode, the load-displacement curve and the ultimate bearing capacity of the finite element analysis are in good agreement with the experimental ones. Based on eccentric compression test and parametric finite element analysis, the calculation formula for the equivalent slenderness ratio was proposed and the bearing capacity of TCFST composite columns under eccentric compression was calculated. Results of theoretical calculation, parametric finite element analysis and eccentric compression experiment accord well with each other, which indicates that the theoretical calculation method of the bearing capacity is advisable.

• KSTLE International Journal
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• 제4권2호
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• pp.37-42
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• 2003

One of the obstacles for a magnetic bearing to be used in the wide range of industrial applications is the failure modes associated with magnetic bearings, which we don't expect for conventional passive bearings. These failure modes include electric power outage, power amplifier faults, position sensor faults, and the malfunction of controllers. Fault-tolerant magnetic bearing systems have been proposed so that the system can operate in spite of some faults in the system. In this paper, we designed a fault-tolerant magnetic bearing system for a turbo-molecular vacuum pump. The system can cope with the actuator/amplifier faults which are the most common faults in a magnetic bearing system. We implemented the existing fault-tolerant algorithms to experimentally prove the adequacy of the algorithms for industrial applications. As it turns out, the system can operate even with three simultaneously failing poles out of eight actuator poles.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.401-414
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• 2010

Top Base Foundation(TBF) is a stabilization method for light weight structures particularly in the soft ground. It is widely used for the increment of bearing capacity and restraining settlement of foundations when the bearing capacity of ground is not enough. However, when the design values from exiting Japanese standard are compared with the observation values from the field measurement, the bearing capacity of exiting standard estimated smaller For this reason, it is necessary to establish more reasonable prediction technique considering to understand the behavior of TBF in soft ground. In this study, 1/5 scale model tests were performed in the laboratory. Also, full scale tests were carried out in order to investigate the behavior of TBF with various shapes. In addition, about 100 sites measurement data were evaluated to investigate the behavior of TBF in various ground conditions. Based on the results of the model tests and field measurement data, it was possible to establish more reasonable the bearing capacity equation of TBF considering various N-value of soil, the effect of underground water and failure shapes.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.544-551
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• 2004

Piles are structural elements made of steel, concrete or timber, and utilize as pile foundation which is one of deep foundations. Driven pile among them, which drives pile into the ground, is fast-constructable, less expensive and it supplies much bearing capacity. For these reasons, its demand is steady. In this study, by selecting the cases which reached ultimate failure during in-situ static loading tests, bearing capacities acquired from these tests were compared with those computed by existing theories and formula. As the results of the analysis, ultimate bearing capacity computed by theoretic formula were less or similar to those of test results in most cases, but lower ground water level and more dense layer where end of piles were reached remarkably high bearing capacity in theoretical methods. ${\beta}-method$ and Korean structure foundation design standard were sensitive to ground physical properties. Meyerhof metbod and API code were relatively independent from site condition.

• Steel and Composite Structures
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• 제20권3호
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• pp.487-500
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• 2016

In order to investigate the flexural bearing capacity of panel zone of diaphragm-through joint between concrete filled square steel tubular column and steel beam, four specimens were tested under static tension loads to study the mechanical properties and bearing capacity of diaphragm-through joints with a failure mode of panel zone. Finite element models of these specimens were developed to simulate the test and compare the predicted failure modes, load-displacement curves and bearing capacities with the experimentally observed. It was found that the tensile load from the steel beam flange is mainly shared by the square steel tube and the diaphragm. The diaphragm plastic zone appears along the cross-section lines enclosed by the square steel tube and the influence of steel beam web on the plastic zone of the steel tube is significant and cannot be neglected. Computational models of yield lines on square steel tube and diaphragm are established based on the distribution pattern of the plastic zone, and an analytical method for the evaluation of the bearing capacity of the joint is proposed. The theoretical results and the experimental data are compared and found in good agreement.

• 한국지반공학회논문집
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• 제26권7호
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• pp.135-145
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• 2010

최근까지 국내에서는 팽이기초에 관한 연구가 미흡하였고, 지반조건에 맞는 설계기준이 마련되어 있지 못하여 일본의 설계기준을 그대로 사용하고 있는 실정이다. 이로 인해 기존 팽이기초의 지지력식은 과소하게 예측되는 문제점이 있다. 따라서 본 연구에서는 실제크기의 1/5 스케일로 축소한 모형실험을 수행하였으며, 국내에서 이루어 진 100여개 현장의 재하실험 결과를 근거로 강도특성(N값), 지하수영향, 팽이기초의 파괴형상을 고려하여 보다 합리적으로 팽이기초의 지지력을 예측할 수 있는 식을 제안하였다.

• Computers and Concrete
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• 제31권5호
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• pp.443-455
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• 2023

This is a research analyses on the bearing capacity at a pile tip embedded in rock. The aim is to propose a shape coefficient for an analytical solution and to investigate the influence of the plastic flow law on the problem. For this purpose, the finite difference method is used to analyze the bearing capacity of various types and states of rock masses, assuming the Hoek & Brown failure criterion, by considering both plane strain and an axisymmetric model. Different geometrical configurations were adopted for this analysis. First, the axisymmetric numerical results were compared with those obtained from the plane strain analytical solution. Then the pile shape influence on the bearing capacity was studied. A shape factor is now proposed. Furthermore, an evaluation was done on the influence of the plastic flow law on the pile tip bearing capacity. Associative flow and non-associative flow with null dilatancy were considered, resulting in a proposed correlation. A total of 324 cases were simulated, performing a sensitivity analysis on the results and using the graphic output of vertical displacement and maximum principal stress to understand how the failure mechanism occurs in the numerical model.