• 한국생산제조학회지
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• 제26권1호
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• pp.1-5
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• 2017

This study investigated the mechanical tearing of a cell membrane using a nanostructured alumina filter for easy and quick mechanical cell disruption. Nanostructured alumina filters were prepared by a multi-step aluminum anodizing process and nanopore etching process. Six different types of nanostructures were formed on the surface of the nanoporous alumina filters to compare the mechanical cell disruption characteristics according to the shape of the nanostructure. The prepared alumina filter was assembled in a commercial filter holder, and then, NIH3T3 fibroblast cells in a buffer solution were passed through the nanostructured alumina filter at a constant pressure. By measuring the concentration of proteins and DNA, the characteristics of mechanical cell disruption of the nanostructured alumina filter were investigated.

• Journal of Magnetics
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• 제19권2호
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• pp.130-139
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• 2014

This paper focuses on the modeling and analysis a novel two-axis rotary normal-stress electromagnetic actuator with compact structure for fast steering mirror (FSM). The actuator has high force density similar to a solenoid, but its torque output is nearly a linear function of both its driving current and rotation angle, showing that the actuator is ideal for FSM. In addition, the actuator is designed with a new cross topology armature and no additional axial force is generated when the actuator works. With flux leakage being involved in the actuator modeling properly, an accurate analytical model of the actuator, which shows the actuator's linear characteristics, is obtained via the commonly used equivalent magnetic circuit method. Finally, numerical simulation is presented to validate the analytical actuator model. It is shown that the analytical results are in a good agreement with the simulation results.

• Journal of Mechanical Science and Technology
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• 제16권11호
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• pp.1497-1510
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• 2002

The onset of cavitation causes head and efficiency of a main pump to be reduced significantly and generates vibration and noise. In order to avoid these phenomena, the inlet of the pump is fitted with a special rotor called an inducer, which can operate satisfactorily with extensive cavitation. The motivation of this study is to find out cavitation modes from the inducer inlet pressure signals and event characteristics from outlet ones at various operating conditions. The cavitation modes are analyzed by using a cross-spectral density of fluctuating pressures at the inducer inlet. The time-frequency characteristics of wall pressures downstream of the inducer are presented in terms of event frequency, its duration time, and number of events by using the Choi-Williams distribution.

• Journal of Mechanical Science and Technology
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• 제16권12호
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• pp.1664-1672
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• 2002

Gantry mechanisms have been widely used for precision manufacturing and material handling in electronics, nuclear, and automotive industries. Dual-drive servo mechanism is a way to increase control bandwidth, in which two primary axes aligned in parallel are synchronously driven by identical servo motors. With this mechanism, a flexible coupling (compliance mechanism) is often introduced in order to avoid the damage by the servo mismatch between the primary drives located at each side of gantry. This paper describes the design guidelines of the dual-drive servo mechanism with focus on its dynamic characteristics and control ramifications. That is, the effect on the system bandwidth which is critical on the system performance, the errors and torques exerted on guide ways in case of servo mismatch, the vibration characteristics concerned with dynamic error and settling time, and the driving force required at each axis for control are thoroughly investigated.

• 열처리공학회지
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• 제8권3호
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• pp.222-228
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• 1995

Mechanical alloying behaviour was investigated after adding 6, 8, 12wt% Fe powder into A1 matrix, respectively, in order to develop Al alloy. And the mechanical characteristics of the alloy which was produced by the above method were studied. The hardness and ultimata tensile strength of the material with different compositions were found to be increased with annealing temperatures and holding times. Intermetallic compound of $Al_3Fe$ and carbide of $Al_4C_3$ phases, which were generated from the different compositions during annealing, were found. It was suggested that enhancement of mechanical properties of Al-Fe alloy system was due to the presence of these preapitates that constrained grain growth and blocked dislocation movement in the alloy system.

• Journal of Mechanical Science and Technology
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• 제17권7호
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• pp.1016-1025
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• 2003

The rupture of blood vessels in the human brain results in serious pathological and medical problems. In particular, brain hemorrhage and hematomas resulting from impact to the head are a major cause of death. As such, investigating the tensile behavior and rupture of blood vessels in the brain is very important from a medical point of view. In the present study, the tensile characteristics of the blood vessels in the human brain were analyzed using a quasi-static uniaxial tensile test, and the properties of the arteries and veins compared. In addition, to compare the tensile behavior and demonstrate the validity of the experimental results, blood vessels from the legs of pigs were also tested and analyzed. The overall results were in accordance with the histological structures and previous medical reports.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.158-163
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• 1992

This paper describes the estimation of the solid friction in mechanical systems by using the extended Kalman filtering techniques. We proposed two stochastic model for the estimation. The one is the 'parametric model' which represents the friction characteristics by an exponential function with unknown parameters. The other is the 'blind model' which does not assume an explicit model but regard the effect of the friction as an unknown input to a known dynamic system. For both models, we give estimation algorithms to generate the filtered estimate and the smoothed estimate with a fixed lag. The filtered estimate can be generated on-line for compensating the solid friction in mechanical systems. Although on-line applications are impossible, the smoothed estimate is more accurate and can be used to grasp precise friction characteristics. Simulation and experimental results arc presented to show the effectiveness of the proposed techniques.

• Journal of Mechanical Science and Technology
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• 제16권4호
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• pp.436-447
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• 2002

In this study, the dynamic response of a catenary system that supplies electrical power to high-speed trains is investigated. One of the important problems which is accompanied by increasing the speed of a high-speed rail, is the performance of stable current collection. Another problem which has been encountered, is maintaining continuous contact force between the catenary and the pantograph without loss of panhead. The dynamic analyses of the catenary based on the Finite Element Method (FEM) are performed to develop a pantograph suitable for high speed operation. The static deflection of the catenary, the stiffness variation in contact lines, the dynamic response of the catenary undergoing the force of a constantly moving load and the contact force were calculated. It was confirmed that a catenary model is necessary to study the dynamic characteristics of the pantograph system.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.309-314
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• 2008

increased heat dissipation and higher heat density of electronic equipment and/or parts released. A loop heat pipe(LHP) has been payed closer attention to the potential candidate of an electronic cooling. As of the LHP with a circular plate type evaporator developed, this study focused on its operating characteristics on the steady state in accordance with charging different working fluid. The relationship between working fluid and operating characteristics is discussed.

• 대한기계학회논문집A
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• 제40권2호
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• pp.139-145
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• 2016

본 연구에서는 나노클레이 함량에 따른 나노클레이-에폭시 나노복합재료의 흡습 특성 및 기계적 특성을 실험을 통해 분석하였다. 나노복합재료의 흡습 시험, 인장시험 및 접착조인트를 나노클레이 함량에 따라 구성하였으며 이를 통해 수분 포화도, 수분 확산 계수, 인장 강도 및 접착 강도와 같은 특성을 파악 할 수 있었다. 또한 나노클레이 및 에폭시 재료를 분자단위로 모델링하여 재료의 흡습 특성변화의 매커니즘을 분석할 수 있는 분자동역학 시뮬레이션을 수행하였으며 그 결과를 실험결과와 비교하여 고찰하였다. 본 연구에서 제안된 분자동역학 시뮬레이션 기법은 흡습특성의 변화를 성공적으로 예측할 수 있었으며, 추후 다른 나노-복합재료의 연구에도 널리 활용될 것이라 기대된다.