• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.520-525
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• 2011

As worldwide concern stands on global warming and greenhouse gases from internal combustion engine, the interests in technologies for a highly efficient powertrain has been increased. Concurrently the investigation to improve the deteriorated NVH, a by-product of energy efficient powertrain, is conducted seriously. The NVH performance of a new type of active engine mount that offers increased advantages over a passive hydraulic mount is examined using a newly developed 6-DOF simulator. The simulator is in the shape of Hexapod Stewart Platform adopting LEMA, a new type of actuator which is patented and commercialized by ACT Inc,, the world wide leader in the design, development, and manufacture of high performance linear electro-magnetic actuators for active vibration control. The target vibration signals of an aimed vehicle at four engine mounts are measured and simulated by 6-DOF simulator at the laboratory. The resulting NVH performances of the new active mounting system at a vehicle and on a simulator are examined and compared. Even though the active mount performance of lab test demonstrates less effective than the result of a real vehicle test, vibration reduction is identified through the simulator.

• 한국자동차공학회논문집
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• 제9권3호
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• pp.60-67
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• 2001

As a method of variable valve train(VVT), Electro-Mechanical Valve(EMV) has been studied. Compared with conventional VVT system, the EMV system has a relatively simple structure. The system has two electromagnets, springs and an armature. The system can be operated by reciprocal action between armature and two electromagnets. And, the operating event can be controlled by electrical signal from controller. Therefore, reduction of emission and fuel consumption can be achieved through valve event control at each engine operating condition. In this study, characteristics of EMV system were investigated by simulations and experiments. The results of simulation and experiment show that the core shape and material characteristics are dominant parameters on magnetic force and delay time. In order to apply the system to commercial engine, it has a compact size and high stiffness springs(50N/mm) to increase the valve speed. Because of high valve seating velocity, loud noise and high impact force generated, which can lead to reduction of actuator durability. Therefore, further research is required to reduce valve seating velocity.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.780-785
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• 2003

Recently the trends in information storage devices need small size, mobility, high capacity, and low power consumption etc. To satisfy those, the development of high performance actuator is an important issue. Compared with general linear actuator for optical disk drive, swingarm type rotary actuator is suitable to design in small form factor and has fast access time for random access. Swingarm actuator is designed considering the structural problem and the actuating force of VCM(Voice Coil Motor). The increase of mass caused by optical components makes vibration problems of swing-arm, therefore resonance frequency should be increased and inertia has to be reduced. ANSYS FEM tool is employed in optimizing swingarm. The VCM is designed using 3-D electro-magnetic analysis, and parameters of magnetic circuit are determined to matte large flux density. The large flux density enables to achieve low power consumption. VCM holder is designed to get the mass balance of total actuator and this balance reduces the magnitude of critical mode relative to pivot bearing, It is expected that swingarm type rotary actuator designed by this method is available to variable type of micro optical disk drives.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1144-1149
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• 2001

In this paper, a sliding mode controller of a fluid engine mount using MR (Magneto-Rheological) fluid was discussed When the MR fluid is applied to a fluid mount, resistance of MR fluid can be controlled by electro-magnetic valve installed in the inertia track. Since the rheological property of the MR fluid shows a function of shear rate, the damping characteristics of the mount will be change according to the frequency. Changing an applied magnetic field to the valve changes the property of the mount, such as the resistance of the MR fluid, the notch and the resonant frequencies due to the fluid passing, quantity of the fluid passing, the effective piston area of the volumetric damping and stiffness. Therefore, the fluid mount using MR fluid can be regarded as a variable structure system The sliding mode control known well as a particular type of variable structure control was introduced in this study. The sliding mode control, which has inherent robustness, is also expected to improve the control performance in the engine mount The sliding mode controller for the mount formatted by taking into account the response property with a time constant to MR fluid and the variable mount property. The motion equations of the fluid mount are derived from Newton's law of motion and used in numerical simulation. Numerical simulations illustrate the effectiveness of the sliding mode controller.

• 소음진동
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• 제11권1호
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• pp.141-146
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• 2001

This paper deals with an application of Magneto-Rheological (MR) fluid to a small size mount for precision equipment of automobiles. MR fluid is known as a class of functional fluids with controllable apparent viscosity of fluid by the applied magnetic field strength. A typical MR fluid is a suspension where pure iron particles of 1-20 (m in diameter are dispersed in a liquid such as mineral oil or silicone oil, at the concentration of 20 - 40 vol%. Electro magnetic coil is installed at the bottom of a variable-damping mount filled with MR fluid, and performance of the mount was investigated experimentally. Furthermore, the Properties of the MR Mount on experimental study were explained analytically by mechanical model of the MR mount.

• 대한금속재료학회지
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• 제46권8호
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• pp.506-515
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• 2008

Recently, it is exceedingly required to produce metal powders with tailored shape and phase altogether in order to fabricate high performance functional parts such as magnetic core or electro-magnetic noise suppressor for high frequency usage. Therefore, the collision phenomena of in-flight droplets against chamber wall or neighboring in-flight droplets each other is investigated by a computational method in order to get useful information about how to design the atomizing system and how to tailor process parameters not to make irregular-shaped powders during gas atomization process. As a results, smaller powders, lower melt temperature are known to be favorable for droplets not to collide against chamber wall. In additions, powders of narrower size distribution range, lower droplet generation rate, lower melt temperature, lower gas velocity are desirable to prevent droplet-collisions against neighboring in-flight droplets.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.525-528
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• 2008

The dynamic range of MR damper is the most important characteristics for the usage of semi-active control system. The damping force can be increased by simply decresing the orifice gap in the traditional oil damper, but it deteriorate the dynamic range in MR damper. In this paper, the multi-stage electro-magnetic core is suggested to maintain the performance of MR damper with a large damping force. The MR damper with 3 stage core is designed and manufactured for testing and analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1995년도 춘계학술대회논문집; 전남대학교, 19 May 1995
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• pp.45-50
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• 1995

본 연구에서는 기존에 널리 사용되고 있는 스카이훅 제어 알고리즘(skyhook control algorithm)[3]을 바탕으로 확장 개발된 모드 스카이훅 제어(mode skyhook control) 개념 및 주파수 감응식 제어(frequency dependent control)개념[4][5]을 실용화하기 위하여 응답속도가 20msec이하의 비교적 빠른 응답 속도를 갖는 전자기식 작동기 (electro-magnetic actuator)에 의해 가변되는 4단 반능동형 가변 댐퍼 시스템을 개발한 후, 다음과 같은 성능의 향상을 시험결과를 통하여 보이고자 한다. -저속에서의 승차감 향상과 고속에서의 주행 안정성 향상 -커브 주행 또는 급격한 핸들 작동시의 롤안정성 (rolling stability) 향상 -제동 및 급발진시의 차체 피칭 운동 방지 (anti-dive, anti-squat)

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.342-345
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• 2004

We design a new actuator in order to achieve 3-axes motion for high performance optical device. The actuator makes it possible to control the tilting motion by using moving magnet and PCB-coil, which have benefits in terms of prices and manufacturing. To predict the features of actuator, especially the effect of moving magnet, finite element method and electro-magnetic analysis are used From comparing simulated data with experimental results, we verified the accuracy of the simulation and the superiority of the present actuator.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.675-680
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• 2004

In this study, a turbine simuiator is designed and manufactured to investigate the transient response of an actual turbine. The rotor mass and bearing stiffness is reduced to 1/140 of its actual turbine. The dynamic characteristics of turbine simulator are similar to those of the actual turbine. The turbine simulator is excited by an electro-magnetic type exciter in the form of half sine wave. Duration time is con☞oiled by Sms, 10ms, and Isms, and maximum acceleration is applied by 3g. Foundation excitation test is performed in stationary condition and rotating condition(6000rpm). The test results can be used to verify the validif of the theoretical afproach for transient analysis of actual turbine.