• 한국정밀공학회지
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• 제20권11호
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• pp.171-179
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• 2003

This paper presents a rehabilitation exercise system which utilizes a 6 DOF robot as a motion generator. This system was proposed for a stroke patient or a patient who has hemiplegia. A master-slave system was designed to exercise either paralysis or abnormal limb by using normal limb motion. The study on the human body was applied to calculate the motion range of elbows and shoulders. In addition, a force-torque sensor was applied to the slave robot to estimate the rehabilitation extent of the patient. Therefore, the stability of the rehabilitation robot could be improved. By using the rehabilitation robot. the patients could exercise by themselves without assistance. In conclusion, the proposed system was verified by computer simulations and system experiment.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.504-507
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• 2009

The purpose of this work is to predict the low frequency aero-acoustic noise generated from the horizontal axis wind turbine, NREL Phase VI using large eddy simulation and Ffowcs-Williams and Hawkings model provided in the commercial code, FLUENT. Calculated aerodynamic performances such as shaft torque and power are compared with experimentally measured value. Performance results show a good agreement with experimental data within about 0.8%. If the distance by two times is changed from 32D to 64D toward the downstream region, sound pressure level is reduced by about 6.4dB.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.44-50
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• 2002

Theoretical analysis on the transient torsional vibration was started from early 1960's for high power synchronous motor application. As for marine engineering, simulation and measuring techniques of transient torsional vibration have been steadily studied by manufacturer of flexible coupling and designer of four stroke marine diesel engine. In this paper, the simulation method of transient torsional vibration for four stroke marine diesel engine application using Newmark method is introduced.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.319-322
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• 2005

This paper describes practical tuning methods and testing of a digital PSS, which uses both frequency and power, with the 220MVA Chungpyung P/P #1 in the KEPCO system to enhance the damping of local modes. In the first step, the objective phase of PSS is computed through a phase leading function to provide compensation between the exciter reference point and the generator air-gap torque before tuning the PSS's time constants. In addition, eigenvalue analysis was used to determine a range of PSS's gain, whichis the more useful for field testing rather than a single gain value. The Real-Time Digital Simulator was used to verify safe operations of the PSS in the presence of disturbances, such as AVR step and three phase fault.

• International Journal of Control, Automation, and Systems
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• 제3권spc2호
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• pp.262-269
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• 2005

In this paper, a nonlinear robust control approach is applied to design a controller for the Static Synchronous Compensator (STATCOM). A robust control dynamic model of STATCOM in a one-machine, infinite-bus system is established with consideration of the torque disturbance acting on the rotating shaft of the generator set and the disturbance to the output voltage of STATCOM. A novel recursive approach is utilized to construct the energy storage function of the system such that the solution to the disturbance attenuation control problem is acquired, which avoids the difficulty involved in solving the Hamilton-Jacobi-Issacs (HJI) inequality. Sequentially, the nonlinear disturbance attenuation control strategy of STATCOM is obtained. Simulation results demonstrate that STATCOM with the proposed controller can more effectively improve the voltage stability, damp the oscillation, and enhance the transient stability of power systems compared to the conventional PI+PSS controller.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.800-804
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• 2005

Load flow and short circuit fault transients of a power distribution system with wind turbines as dispersed generation units is presented. Usage of renewable energies such as wind is already a small part of total installed power system in medium and low voltage networks. In this paper, a radial power distribution system with wind turbines is simulated using DIgSILENT PowerFactory software for their influence on load flow and short circuit fault transients. Short fault occurring in dispersed generation systems causes some problems for the system and costumers such as fault level increase or the problems of sudden fluctuations in the current, voltage, power and torque of the double fed induction machine utilized in the wind turbines which have been studied and investigated.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2003년도 제21회 추계학술대회 논문집
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• pp.257-260
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• 2003

스마트 무인기용 터보제트 엔진의 동적 성능모사 프로그램을 개발하였다. 천이 성능 프로그램에는 일정공기유량(Constant Mass Plow) 방법을 적용되었으며 잉여토크의 적분에는 오일러 적분법을 이용하였다. 천이성능해석은 가스발생기의 아이들로부터 최대 회전수까지 증가하는 것을 수행하였다. 엔진의 동적거동을 살펴보기 연료유량을 step과 ramp 증가로 주었다. 연료가 step으로 증가되었을 때 터빈 입구온도에서 오버슈트가 발생하였으며 연료유량을 0.6sec 이상으로 증가시켰을 때 오버슈트가 제거됨을 확인할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.321-321
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• 2010

In this paper, we propose a novel type shaft-less ring type ultrasonic motor. A traveling wave rotary type ultrasonic motor is selected as a base model. The newly designed stator has two piezoelectric ceramic rings which are bonded in sandwich shape as traveling wave generator. So, we can expect to produce higher torque. The proposed model has the rotor structure that coupled with the stator provokes the pressure, this model do not install the separate plate any spring device. We used the finite element method to verify the operation principle and to compute the vibration mode of proposed model.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.287-290
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• 2006

Orbiter mechanism has been applied to vacuum pump design for small oxygen generator where low vacuum of about 200mmHg is required. Performance of the designed vacuum pump has been numerically investigated: calculated volumetric and adiabatic efficiencies were 69.7% and 83.9%, respectively for leakage clearance of $10{\mu}m$. Total efficiency of the orbiter vacuum pump was 77.5%. At the shaft speed of 1700 rpm suction displacement volume of 6.3cc provided discharge flow at the rate of 2.3 liter/min with power consumption of 10.1Watt. Torque variation of the orbiter pump was only about 20% of that of diaphragm pump.

• 대한기계학회논문집A
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• 제33권1호
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• pp.42-48
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• 2009

A design methodology for control strategy and control structure gives a direct impact on wind turbine's performance and life cycle. A baseline control law which is a variable rotor speed and variable pitch control strategy is introduced, and a mathematic performance model of a wind turbine dynamics is derived. By using a numeric optimization algorithm, the steady state operating conditions of wind turbines are identified. Because aerodynamic interaction of winds with rotor blades is basically nonlinear, a linearization procedure is applied to analyze wind turbine dynamic variations for whole operating conditions. It turns out the wind turbine dynamics vary much depending on its operating condition.