• 한국지반공학회논문집
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• 제32권12호
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• pp.5-13
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• 2016

본 연구에서는 대변형 해석기법 중 하나인 Coupled Eulerian-Lagrangian 해석기법을 적용하여 TBM 굴진으로 발생하는 굴착손상영역을 분석하였다. 실제 TBM 굴진과정을 모사하기 위해 quasi-static 조건을 고려하여 동적해석을 수행하였으며, 해석시간의 효율성과 정확도를 만족시키는 최적의 조건을 찾기 위해 mesh 및 TBM 굴진속도를 변수로 하여 case study를 수행하였다. 또한 암반 종류 및 터널 직경이 굴착손상영역에 미치는 영향을 확인하기 위해서 매개변수연구를 수행하였다. 수치해석 결과, TBM 굴착으로 인한 굴착손상영역은 대부분의 경우 0.4D 이내로 나타났으며, 터널직경이 커짐에 따라 굴착손상영역도 증가하는 것으로 나타났다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.244-249
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• 2002

Rubber seat is extensively used to reduce the vibration of machine or structure. Over the years an enormous effort has been put into developing procedures to provide properties of rubber material for design function. However, there are still a lot of difficulties to analyze static characteristics of rubber components with hyper elasticity and nonlinear large deformation. In this paper material property is obtained by strain-stress curve using a tension test. Mooney-Rivlin Coefficients are gotten by fitting strain-stress curve. The visco-elastic characteristics of refrigerator rubber mount is determined by using ANSYS. And to minimize the rubber stiffness, the rubber seat shape optimization is performed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.330.1-330
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• 2002

Elastomer is extensively used to reduce of vibration machine or structure. Over the years an enormous effort has been put into developing procedures to provide properties of rubber material fur design function. However, there are still a lot of difficulties to analyze static characteristic of rubber components with hyper elasticity and nonlinear large deformation. In this paper material property is obtained by strain-stress curve using a tension test. (omitted)

• 한국공간구조학회논문집
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• 제1권2호
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• pp.85-92
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• 2001

The structural behaviors of anisotropic laminated shells are quite different from that of isotropic shells, Also, the classical theory of shells based on neglecting transverse shear deformation is invalid for laminated shells. Thus, to obtain the more exact behavior of laminated shells, effects of shear deformation should be considered in the analysis. As the length of x-axis or y-axis is increase, the effects of transverse shear deformation are decrease because the stiffness for the axis according to the increasing of length is large gradually. In this paper, the governing equations for anisotropic laminated shallow shell including the effects of shear deformation are derived. And then, by using Navier's solutions for shallow shells having simple supported boundary, extensive numerical studies for anisotropic laminated shallow shells were made to investigate the effects of shear deformation for 3 typical shells. Also, static analysis is carried out for cross-ply laminated shells considering the effects of various geometrical parameters, e,g., the shallowness ratio, the thickness ratio and the ratio of a(length of x-axis)-to-b(length of y-axis). The results are compared with existed one and show good agreement.

• 한국철도학회논문집
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• 제13권1호
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• pp.84-91
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• 2010

본 연구에서는 철도, 도로 등 대형 성토지반구조물의 주요 지반재료인 입경이 큰 조립재료에 대해 전단강도, 변형계수, 응력-변형 거동과 같은 지반공학적 설계정수를 평가 산정할 수 있는 대형삼축압축시험장비를 구축하고, 이를 활용한 도상자갈재료에 대한 정적삼축압축시험 결과를 통해 그 의미와 적용 가능성을 제시하였다. 도상자갈과 같이 지표면에 설치되어 포화 가능성이 낮고, 구속압이 작은 경우에는 진공압(vacuum)으로 구속압을 제어하는 방식이 효과적임을 확인할 수 있었다. 도상자갈 재료의 삼축압축시험 결과로부터 구속압별 전단강도, 변형계수, 입자파쇄 영향 등의 합리적인 결과와 경향을 확인하였으며, 모암의 입자강도, 구속압 등의 영향을 고려하여 전단강도 포락선을 예측할 수 있는 비선형식에 적합한 재료 상수를 산정, 적용하여 실험 결과를 근접하게 재현해낼 수 있었다.

• Smart Structures and Systems
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• 제20권2호
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• pp.151-162
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• 2017

In practical engineering, the friction damper is a widely used energy dissipation device because of its large deformation capacity, stable energy dissipation capability, and cost effectiveness. While based on conventional friction dampers, the double-sliding friction damper (DSFD) being proposed is different in that it features two sliding friction forces, i.e., small and large sliding friction forces, rather than a single-sliding friction force of ordinary friction dampers. The DSFD starts to deform when the force sustained exceeds the small-sliding friction force, and stops deforming when the deformation reaches a certain value. If the force sustained exceeds the large sliding friction force, it continues to deform. Such a double-sliding behavior is expected to endow structures equipped with the DSFD better performance in both small and large earthquakes. The configuration and working mechanism of the DSFD is described and analyzed. Quasi-static loading tests and finite element analyses were conducted to investigate its hysteretic behavior. Finally, time history analysis of the single-degree-of-freedom (SDOF) and multi-degree-of-freedom (MDOF) systems were performed to investigate the seismic performance of DSFD-equipped structures. For the purpose of comparison, tests on systems equipped with conventional friction dampers were also performed. The proposed DSFD can be realized perfectly, and the DSFD-equipped structures provide better performances than those equipped with conventional friction dampers in terms of interstory drift and floor acceleration. In particular, for the MDOF system, the DSFD helps the structural system to have a uniform distributed interstory drift.

• 대한의용생체공학회:의공학회지
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• 제24권3호
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• pp.233-239
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• 2003

측방 낙상에 관계된 상해는 노인들에 있어서 가장 치명적이고 빈번한 의료 문제를 야기한다. 측방 낙상에 의해 발생하는 심각한 결과 중 하나인, 고관절 골절은 넘어진 사람 중 약 1%에서만 발생하지만 고관절 골절은 신체장애, 사망 및 이에 관련된 의료비용의 상승 등을 초래한다. 본 연구에서는 측방 낙상시 고관절 골절에 큰 영향을 미치는 충돌 단계에서의 위험요소를 하중각도로 가정하여 이 요소에 대한 영향과 직립시와 비교하여 상대적인 위험도를 비교하고자 하였다. 실험 조건은 이전 연구자의 자료를 토대로 모사골반을 구성하였고, 이렇게 구성된 모사골반을 진자형 충격 시험기에 고정시키고 충격각도(0$^{\circ}$, 15$^{\circ}$, 30$^{\circ}$)를 변화시켜가며 대퇴골의 동적 거동을 조사하였다. 본 실험을 통하여 하중각도의 변화가 대퇴골 근위부에서의 변형에 영향을 주며, 다른 부위에 비해 대퇴골 경부에 상대적으로 큰 변형이 생겨 골절 가능성이 높다는 것을 확인하였다. 또한 낮은 충격속도에서도 직립 상태에 비해 큰 변형을 보였으며, 변형 분포의 차이도 나타내었다. 따라서 변형 크기의 차이뿐만 아니라 이러한 변형 분포의 차이도 고관절 골절 기전에 영향을 줄 것으로 사료된다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1335-1340
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• 2007

The media transport systems, such as printers, copy machines, facsimiles, ATMs, cameras, etc. have been widely used and being developed rapidly. In the development of those sheet-handling machineries, it is important to predict the static and dynamic behavior of the sheet with a high degree of reliability because the sheets are fed and stacked at such a high speed. Flexible media are very thin, light and flexible, so they behave in geometric nonlinearity with large displacement and large rotation but small strain. In the flexible media analysis, aerodynamic effect from the surrounding air must be included because any small force can make large deformation. In this paper, surrounding air was modeled by incompressible Navier-Stokes flow and an arbitrary Lagranigan-Eulerian(ALE) finite element method with automatic mesh-updating technique was formulated for large domain changes. In the numerical simulations, the results with consideration of the air fast decayed and converged into static results while the results without considering air oscillated continuously.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.115-122
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• 2005

This study analyzed the characteristics of four kinds of bridge rubber pads and suggested how to determine the stiffness the pads. The stiffness of rubber pads can be estimated by a direct static test. In the procedure to estimate the stiffness of a pad, the dead load(preload) of a bridge and live load of a vehicle are considered. The polyurethane rubber pads have larger hardness than natural and chloroprene rubber pads and thus carry larger load bearing capacity. In addition, they showed higher stiffness with the same shape factor than the others and thus are more avaliable as for bridge bearings. Although natural and chloroprene rubber pads are elongated to large deformation in horizontal direction due to vertical loads, polyurethane rubber pads almost do not generate horizontal deformation due to vertical loads regardless to the thickness and hardness of the pads. Therefore, they do not need reinforced plate to restrict horizontal deformation.

• 대한기계학회논문집A
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• 제33권8호
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• pp.760-766
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• 2009

In the manufacturing process of HDD, ball swaging method is commonly used to joint the Head Gimbal Assembly(HGA) with the arm of the actuator. The hub on the HGA is placed into the hole of the actuator arm, and the hub and arm is bonded by the pressure of steel ball. The pressure for plastic deformation on the baseplate causes the undesirable deformation on HGA, such as tilting, flying height change of head. After obtaining the key parameters that have large sensitivity on the swaging process, the optimal shape of baseplate is proposed to increase the static performance during swaging process. Contribution of the proposed design for the swaging performance is verified by contact simulation with elasto-plastic deformation.