• Korea-Australia Rheology Journal
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• 제18권3호
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• pp.121-126
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• 2006

A carbonyl iron-based magneto-rheological suspension was compressed in the direction of the applied magnetic field and the change in rheological properties was measured. It was found that the compression did not have a large effect on the magneto-rheological response, which is in contrast to recent reports in the literature describing an almost order of magnitude increase in the shear yield stress. The difference can be attributed to the latter test's use of a sliding wedge apparatus which imparts considerable shearing to the sample during the compression.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.546-551
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• 1997

New typology of failure mechanisms for uniform compression fields are presented based on the classical theory of plasticity, in particular th normality rule, and the limit theorem. The concrete is assumed as a rigid-perfectly plastic material obeying the modified Coulomb failure criteria with zero tension cut-off. The failure mechanisms are capable of explaining flexural types of crushing failure in uniaxial uniform compression stress fields which are called struts in truss models. The failure mechanisms consist of sliding failure along straight failure lines or hyperbolic failure curves and rigid body rotation. The failure mechanisms involving straight failure lines are explained by constant strain expansion in the first principal direction and rigid body rotation motion. The failure mechanisms presented are applied to the explanation of bond failure of bar combined with concrete crushing failure and flexural crushing failure of concrete.

• 제어로봇시스템학회논문지
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• 제17권12호
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• pp.1266-1272
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• 2011

For way-point tracking of an autonomous underwater vehicle, a state feedback controller was designed by using pole placement scheme in discrete time domain. In the controller, 4 state variables were used for regulating the depth of the vehicle in z direction, and 3 state variables, for steering the vehicle in xy plane. Assuming constant speed of AUV, we simplified the design of the way-point tracking system. The proposed controller was simulated by MATLAB/Simulink using 6 degree-of-freedom nonlinear model and its performance of way point tracking was shown to be fulfilled within 1 m, nevertheless the proposed controller is quite simple and easy to implement compared to sliding mode controller.

• Geomechanics and Engineering
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• 제15권1호
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• pp.669-676
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• 2018

The "pseudo-wedge" failure is a name for a complex instability occurring at the Sarcheshmeh open-pit mine (Iran). The pseudo-wedge failure contains both the rock bridge failure and sliding along pre-existing discontinuities. In this paper, a cross section of the failure area was first modeled using a bonded-particle method. The results indicated development of tensile cracks at the slope toe which explains the freedom of pseudo-wedge blocks to slide. Then, a three-dimensional discrete element method was used to perform a block analysis of the instability. The technique of shear strength reduction was used to calculate the factor of safety. Finally, the influence of geometrical characteristics of the mine wall on the pseudo-wedge failure was investigated. The safety factor significantly increases as the dip and dip direction of the wall decrease, and reaches an acceptable value with a 10-degree decrease of them.

• 대한기계학회논문집
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• 제16권8호
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• pp.1513-1518
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• 1992

본 연구에서는 참고문헌 8의 해법을 응용하여 다발 보의 마찰 접촉 문제를 푸는 방법에 대하여 설명한다. 각 보 요소의 변형은 미소변형 및 Bernoulli-Euler이 론을 이용하여 계산하며, 마찰력 계산을 위하여는 Coulomb 마찰 법칙을 이용한다. 보의 종류와 형상 및 보를 묶는 클램프(clamp)의 종류에 따라서 수 많은 종류의 스프 링이 얻어 질 수 있다. 여기에서는 편의상 보 다발이 클램프에 의하여 강하게 묶여 있으며, 그 묶인 점에서는 각 보의 법선 방향(normal direction) 상대 운동은 없는 것 으로 간주한다.

• 대한기계학회논문집A
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• 제31권3호
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• pp.338-343
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• 2007

Thermal deformation of cast iron exhaust manifold for turbo diesel engine is investigated by finite element analysis (FEA). The FE model included the temperature dependent material properties as well as the interactions between exhaust manifold, cylinder head and fasteners. It also considers the sliding behavior of the flanges of exhaust manifold on cylinder head when either expansion or contraction of the exhaust manifold exceeds the fastener pretension. The result of analysis revealed that remarkable thermal deformation along the longitudinal direction. Compressive plastic deformation at high temperature remained tensile stress in manifold and resulted in longitudinal contraction at ambient temperature. The amount of contraction at each fastener position was predicted and compared with experimental results. Analysis results revealed that the model predicted deformation qualitatively, but more elaborated cyclic hardening behavior would be necessary to predict the deformation quantitatively.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.751-756
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• 2008

This paper presents the fluid characteristics of the spool actuator used for construction vehicles. A spool actuator is used for directional control of pressurized fluid and has a roll to lock the fluid flow. It is important to design the spool actuator optimally because this actuator is actuated in the sleeve by sliding motion and has some critical design parameters such as stick-slip, leakage and shock pressure. The parameters like stick-slip and leakage can be solved by precision manufacturing but the shock pressure which is taken place when the fluid direction is changed needs the parameter analysis procedure throughly. In this study, mathematical modeling and 2 & 3 phase flow dynamics analysis of the spool actuator were achieved. Using suggested model, all possible operating conditions were analyzed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.841-844
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• 2003

In the semiconductor and the optical industry a new transport system which can replace the conventional sliding system is required. These systems are driven by magnetic field and conveyer belt. The magnetic field damages semiconductor and contact force scratches the optical lens. The ultrasonic wave driven system can solve these problem. In this paper, the vibration behavior of flexural beam in the ultrasonic transport system is verified using Laser Scanning Vibrometer. The experiments for verifying vibration are performed in three conditions such as in the maximum transport speed, in the zero speed, and in the change of transport direction.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2004년도 정기학술대회
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• pp.335-342
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• 2004

The failures such as flaking, wear, crack and seizing caused by the high contact pressure accompanied with sliding motion between inner or outer ring and ball are potential failures of ball bearing. In this research, we have qualitatively selected the efficient test items through the analysis of the life and potential failures of ball bearing. The bearing's failures are related closely to the whole system in using the bearing. So, the bearing itself requires an estimation of life in order to opreate the system safely. We have tested ten ball bearings. Our research has applied both radial and axial direction force of maximum torque conditions simultaneously for the accelerated life testing. The result is established by employing the weibull plot and compared the predicted life of ball bearing to the experimental result.

• Smart Structures and Systems
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• 제25권6호
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• pp.643-655
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• 2020

Active control of nonlinear vibration of stiffened functionally graded (SFG) cylindrical shell is studied in this paper. The system is subjected to axial and transverse periodic loads in the presence of thermal uncertainty. The material composition is considered to be continuously graded in the thickness direction, also these properties depend on temperature. The relations of strain-displacement are derived based on the classical shell theory and the von Kármán equations. For modeling the stiffeners on the cylindrical shell surface, the smeared stiffener technique is used. The Galerkin method is used to discretize the partial differential equations of motion. Some comparisons are made to validate the SFG model. For suppression of the nonlinear vibration, the linear and nonlinear control strategies are applied. For control objectives, the piezoelectric actuator is attached to the external surface of the shell and the thin ring piezoelectric sensor is attached to the middle internal surface of shell. The effect of PID, feedback linearization and sliding mode control on the suppression of vibration for SFG cylindrical shell is presented.