• Structural Engineering and Mechanics
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• 제82권6호
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• pp.691-699
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• 2022

This paper is devoted to the presentation of a numerical study on vibration behavior of composite panels reinforced by glass fibres and carbon nanotubes (CNTs) subjected to thermal environments. The effect of temperature variation has been included as thermal load acting on in-plane direction of the panel. To model the composite material, a micromechanical model which contains random dispersion of nanotubes and single-direction fibers has been selected. The geometry of the panel has been considered to have a single curveture along its width. Based on the above assumptions, the governing equations have been derived by using thin shell theory capturing the panel curveture and also nonlinear deflections. Finally, the panel dependence on various factors such as the curveture, nanotube amount, fiber volume, fiber direction and temperature variation has been researched.

• 대한토목학회논문집
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• 제26권6A호
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• pp.955-963
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• 2006

곡선교의 기하학적 특징으로 인하여 곡선교의 지진응답은 직선교와는 다른 응답특성을 나타내게 될 것으로 예상된다. 본 논문에서는 곡선교의 모형화 방법 및 다양한 영향인자들의 적용에 따른 지진응답특성을 분석하고자한다. 곡선교의 지진응답 특성을 분석하기 위하여 일반적으로 사용되는 곡선교의 수치해석모형을 지점부가 보강된 모형으로 개선하였으며, 정밀모형과의 비교를 통하여 개선된 모형의 적합성을 검증하였다. 본 논문에서는 곡선교의 지진응답에 영향을 미칠 수 있는 곡선반경이나 받침배치 조건에 따른 곡선교의 지점부 및 교각에서의 변위와 수평력을 중심으로 분석하였다. 지진하중은 직교되는 2방향으로 작용하는 것으로 가정하여, 지진하중의 작용방향을 변화시키면서 지진응답을 분석하였으며, 대상교량으로는 곡선교의 대표적인 형식인 단경간 곡선교와 3경간 연속 곡선교를 선택하였다. 분석결과, 단경간 곡선교는 고정하중 및 지진하중의 작용으로 인한 지점부의 정반력 및 부반력이 크게 발생할 수 있는 것으로 나타났으며, 연속 곡선교의 경우 대상교량의 곡선 반경에 따라 지진하중의 작용방향에 영향을 받는 것으로 나타났다. 또한, 곡선반경 변화에 따라 접선방향 받침배치와 현방향 받침배치의 지진응답 특성에 차이가 있는 것으로 나타났다.

• 구강회복응용과학지
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• 제21권2호
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• pp.153-167
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• 2005

The purpose of this study was to compare the v-shape thread with the square shape thread of fixture in the view of stress distribution pattern using finite element stress analysis. The finite element model was designed with the parallel placement of two standard fixtures(4.0 mm diameter ${\times}$ 11.5 mm length) on the region of mandibular 1st and 2nd molars. Three dimensional finite element model was created with the components of the implant and surrounding bone. This study simulated loads of 200 N at the central fossa in a axial direction (load A), 200 N at the buccal offset load that is 2 mm apart from central fossa in a axial direction (load B), 200 N at the buccal offset load that was 4 mm apart from central fossa in a axial direction (load C). These forces of load A',B',C' were applied to a $15^{\circ}$ inward oblique direction at that same site with 200 N. Von Mises stress values were recorded and compared in the supporting bone, fixture, and abutment screw. The following results have been made based on this study : 1. The highest stress concentration occurred at the cervical region of the implant fixture. 2. Von Mises stress value of off-site region was higher than that of central fossa region. 3. Square shape thread type showed more even stress distribution in the vertical and oblique force than V-shape thread type. 4. Stress distribution was the most effective in the case of buccal offset load (2, 4 mm distance from central fossa) in the square shape thread type. 5. V-shape thread type revealed higher von Mises stress value than square shape thread type in all environmental condition. The results from numerical analyses concluded that square shape thread type had the lower destructive stress and more stress distribution between the fixture and bone interface than V-shape thread type. Therefore, square shape thread type was regarded as optimal thread configuration in biomechanical concepts.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 D
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• pp.2738-2740
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• 2005

From composition transmitter is detached in indicator to individual load direction of 4 channels and adding up display by load cell indicator indication method of Bluetooth way is identifying marks.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기설비전문위원
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• pp.107-109
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• 2007

From composition transmitter is detached in indicator to individual load direction of 2 channels and adding up display by digital load cell indicator indication method of Bluetooth method is identifying marks.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권6호
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• pp.286-290
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• 2003

The high temperature superconducting bulk can be used as the bearing of induction motors. This paper presents the fabrication and test results of an induction motor with superconducting bearings using HTS bulks. The bearing had eight hexahedron type YBCO bulks. Height, width and thickness of the HTS bulk were 30mm, 30mm and 10mm, respectively. Single phase induction motor was used to drive the shaft made of aluminum and the rotor of a conventional induction motor. To estimate the performance of the HTS bulk magnetic bearing, no load test, load test and Impact test were carried out. Load tests were performed by using air resistance caused by the shaft-mounted thin cylinder with buckets. Impact tests by axial direction and vertical direction impact showed that the vibration of the shaft gradually decayed. The induction motor with HTS bulk magnetic bearing rotated silently and smoothly throughout the tests. According to the test results, conventional bearings can be replaced with superconducting magnetic bearings made of HTS bulks.

• 동력기계공학회지
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• 제16권6호
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• pp.92-97
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• 2012

In this study, ER fluids were working fluid and yield shear stress of attained dispersive ER fluids made by analyzed to adapt effectively at the practical equipment like three port ER valve. In addition, movement of ER particle was observed by using a microscope the same as the strength of electric field with Bingham characteristic. Basis material was presented to develop 3 port ER-Valve by quantitatively comparing and analyzing entrance, load and outlet flow's differences of 3 port rectangular tubes. This study, after designing and producing the 3port ER-Valve, considered the characteristic of pressure drop, outlet and load flow rate by changing the strength of electric field on ER fluids flowing between electrodes.

• Geomechanics and Engineering
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• 제15권3호
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• pp.911-917
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• 2018

This paper concerns a numerical investigation on the effect of construction sequence on three-arch (3-Arch) tunnel behavior. A three-arch tunnel section adopted in a railway tunnel construction site was considered in this study. A calibrated 3D finite element model was used to conduct a parametric study on a variety of construction scenarios. The results of analyses were examined in terms of tunnel and ground surface settlements, shotcrete lining stresses, loads and stresses developed in center column in relation to the tunnel construction sequence. In particular, the effect of the side tunnel construction sequence on the structural performance of the center structure was fully examined. The results indicated that the load, thus stress, in the center structure can be smaller when excavating two side tunnels from opposite direction than excavating in the same direction. Also revealed was that no face lagging distance between the two side tunnels impose less ground load to the center structure. Fundamental governing mechanism of three-arch tunnel behavior is also discussed based on the results.

• 한국철도학회논문집
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• 제9권3호
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• pp.251-256
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• 2006

This paper explains manufacturing process, analysis and experimental studies on a hybrid composite carbody of Korean tilting train. The composite carbody with length of 23m was manufactured as a sandwich structure composed of a aluminium honeycomb core and woven fabric carbon/epoxy faces. In order to evaluate deformational behavior of the composite carbody, the static load test under vertical load has been conducted. From the test, the vertical deflection an겨 cross sectional deformation of the carbody were analysed and measured. The maximum deflection along the side sill was 9.25mm in the experiment and 8.28mm in the analysis. The maximum cross sectional deformation was measured 5.42mm at carbody center in lateral direction and 4.06mm at roof center in vertical direction.

• 대한전기학회논문지:전력기술부문A
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• 제48권8호
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• pp.958-964
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• 1999

The distance in load parameter space to the closest saddle node bifurcation (CSNB) point provides the worst case power margin to voltage instability and the left eigenvector at CSNB identifies the most effective direction to steer the system to maximize voltage stability under contingency. This paper presents an improved direct method for computing CSNB: the order of nonlinear systems equations is reduced to about twice of the size of load flow equations in contrast to about three-times in Dobson's direct method; the initial guess for the direct method is computed efficiently and robustly by combined use of continuation power flow, a pair of multiple load flow solution with Lagrange interpolation. It is also shown that voltage stability may be enhanced significantly with shift of generations in the direction of the left eigenvector at CSNB.