• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.1289-1290
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• 2011

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1828-1831
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• 2005

Time Delay Control (TDC) method was proposed as a promising technique in the robust control area, where the plants have unknown dynamics with parameter variations and substantial disturbances are present. In this paper we concerns vibration control of rotor system using TDC. Based on the rotor system model, the TDC is designed, and the PD-controller is also designed for comparison. The simulation results show that the TDC is much robust than the PD-controller to the unknown dynamics with parameter variations and disturbances.

• 한국정밀공학회지
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• 제32권8호
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• pp.713-718
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• 2015

This article describes the calculation procedure for the dynamic characteristics of a high-pressure labyrinth seal wherein the friction force and rotor whirling force are considered; SFCP, the commercial code developed by Lee and two colleagues, is used in the procedure. The simulation results were reviewed in comparison to those of the experiments provided by Benckert; additionally, the SFCP simulation results were verified using the CFD analysis presented by Toshio Hirano. This calculation procedure may therefore be applied to the dynamic characteristics of the labyrinth seals of high-pressure turbo machinery.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.769-772
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• 1995

Most turbo machines, which operate at high speeds, such as gas turbines, jet engines, pumps, and compressors are prone to perrturbing vibrations. The best vibration control method for rotors is to eliminate destabilizing factors. Careful balancing application of "more stable" oil-lubricated bearing, such as tilting pad bearings or use of anti-swirl devices in seals, are examplse of passive vibration control methods. the use of magnetic bearing is an active control method. An obvious advantage of active control is that it provides damping (or modifies system stiffness or other parameters) only when there is a need for that, i.e., in emergency states, while not affecting the rotor normal operational conditions. Moreover, active control methods provide exact position control through on-line control. In this study, a magnetic actuator, digital contrliier using DSP, and bipolar operational power supply/amplifiers were developed to show the effectiveness of reducing robot vibration. Also the curve fitting procedure to obtain the transfer function of frequency dependent component was developed. Results presented in this dissertation will provide a well-defined technical parameters in designing magnetic damper system.er system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.843-847
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• 2007

The unbalanced mass of a high precision rotor deteriorates mechanical performance of the rotor. The geometrical center of a rotor generally corresponds to the rotational axis of the rotor. However, this alignment carried out with a stationary rotor does not guarantee the dynamic rotor balance. There have been a number of schemes for the correction of the imbalance published for decades especially in the hard drive industry where the issues are directly affecting manufacturing costs and product performances. Realizing the significance of the problem, the present work tries to refine one of the methods that works by applying external impact during a rotor spins. A systematic way to apply the external impact to a rotating rotor has been introduced to minimize imbalance correction process time.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.389-392
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• 1997

This paper presents the dynamic analysis and experiment for rotor systems supported by angular contact ball bearings subjected to axial displacement preload. A dynamic software, which has been developed by the authors for the analysis of rotor systems supported by angular contact ball bearings, is used to simulate a uniform shaft system supported by two angular contact ball bearings with the axial displacement preload varied. Experiments are also performed to validate the simulation. An experimental system is constructed which consists of a uniform shaft, two bearings and a device for adjusting the axial displacement preload. Through a series of simulation and experiment, the dynamic characteristics of rotor systems with angular contact ball bearings subject to axial displacement preload are investigated.

• 한국소음진동공학회논문집
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• 제17권8호
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• pp.720-725
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• 2007

The unbalanced mass of a high precision rotor deteriorates mechanical performance of the rotor. The geometrical center of a rotor generally corresponds to the rotational axis of the rotor. However, this alignment carried out with a stationary rotor does not guarantee the dynamic rotor balance. There have been a number of schemes for the correction of the unbalance published for decades especially in the hard drive industry where the issues are directly affecting manufacturing costs and product performances. Realizing the significance of the problem, the present work tries to refine one of the methods that works by applying external impact during a rotor spins. A systematic way to apply the external impact to a rotating rotor has been introduced to minimize unbalance correction process time.

• 한국정밀공학회지
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• 제19권4호
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• pp.140-146
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• 2002

High speed rotating machines can be very sensitive to rotating mass unbalance that is a major source of harmful vibration for many types of rotating machinery. So, the balancing procedure is needed for all high-speed rotating system. To save the time and cost of off-line balancing, many researchers have developed the on-line balancing devices and methods. In this paper, an active balancing device, which is an electro-magnetic type, is developed and the active balancing algorithm using influence coefficient method is also proposed. The active balancing experiment for flexible rotors during operation is performed by an active balancing device. As a result, controlled unbalance responses are below the vibration limit at all rotating speed ranges with critical speed.

• 한국정밀공학회지
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• 제19권10호
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• pp.37-44
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• 2002

The dynamic behavior of rotor-bearing system has been investigated using finite element method. A procedure is presented for dynamic modeling of rotor-bearing system which consists of shaft elements, rigid disk, flexible bearing and support structure. A finite element model including the effects of rotary inertia, shear deformation, gyroscopic moments is developed. Linear stiffness and damping coefficients are calculated for 2 lobe sleeve bearing. The whirl frequency, mode shape, stability and unbalance response of rotor system including effects of bearing coefficient and support structures are calculated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.1164-1166
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• 1999

본 연구에서는 3차원 회전체 구조물을 제조하기 위해 회전노광장치를 설계하여 제작하고 마이크로렌즈 제작용 X-선 마스크와 PMMA 기판을 정밀하게 회전시켜 노광함으로써 3차원의 마이크로렌즈를 제작하였다. 제작된 마이크로렌즈의 크기는 직경이 $50{\sim}700{\mu}m$이었고, 또한 이러한 방법으로 원통형 렌즈, 계란형 렌즈 등을 제작함으로써 X-선 사진식각공정으로 정밀도가 높은 다양한 3차원의 회전체 구조물을 제조하는 방법을 제시하였다.