• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.86-88
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• 1995

Outer-rotor type brushless motor is designed to run at more constant speed because of large inertia comparing with inner-rotor type. The constant speed is acquired by increasing inertia. Also, the generating torque is proportional to the rotor volume, i. e. rotor diameter. The main idea in this study is to design and analyze the outer-rotor type brushless motor by permeance method with given outer dimension.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.2
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• pp.184-193
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• 2002

This study aims at the optimal design of the screw rotor and its performance analysis. The optimal design of the screw rotor's shape has been performed theoretically. Also, the performance analysis technique of an oil-injected screw air compressor is developed. The effect of internal leakage, heat exchange between air and oil, and flow resistance at suction and discharge ports are included in the performance analysis. Some numerical examples of the volumetric efficiency and adiabatic efficiency for sample rotors are demonstrated for various lobe combination, rotor wrap angles and L/D ratios.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.2
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• pp.26-32
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• 2013

The rotorcraft makes lift and control forces by the rotor thrust. At the development phase of the rotorcraft, the operational limitations have to be established. And it shall be demonstrated to operate the rotorcraft safely within the limitations. This paper introduces establishment and evaluation results of operational rotor speed limitations for the medium class utility rotorcraft. And it shows the follow-up activities after design changes of rotor speed indicators and aural warning systems for implementing the rotor speed limitations.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.153-162
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• 2005

Through a preliminary design process, four design candidates for a 1.4MW class partial admission turbine have been chosen and the numerical analyses using a frozen rotor method are applied to estimate their performance. Each flow analysis result was compared with others and the optimum design was selected. Flow characteristics in the passages and some types of losses induced by shocks and wakes were found from calculation results. A new rotor blade was redesigned based on these calculations and this result is compared with previous one through flow analysis.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.101-102
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• 2002

Indicial response characteristics of a rotor supported by a gas-lubricated, spiral-grooved proceeding bearing are studied theoretically to develop a fundamental investigation for the bearing design with considering NRRO characteristics. The trajectory of rotor movement is calculated by applying the non-linear orbit scheme against a prescribed impulse load, then two characteristic quantities are introduced to evaluate the indicial response performance of the bearing, i.e., 'maximum deviation of rotor center' and 'integrated rotor center deviation'. The effects of some design parameters of spiral grooves to these representative quantities are studied so that 'robust' design against impulse load is discussed.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.485-491
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• 2001

This paper describes the development of simulation program which is able to design cutter profiles and 3-dimensional geometry for rotors in screw compressor. Based on the symmetric rotor profiles developed previously, cutters are designed and 3-dimensional geometries of rotors are generated used by simulation program. Symmetric rotors are manufactured by a universal milling machine, and surface geometries of them are measured by a 3-dimension scanner. It is shown that simulation program developed is useful to design cutter for rotor manufacturing and to generate the 3-dimensional helicoid geometry of rotor in screw compressor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.1034-1037
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• 2002

This paper presents an optimum design of rotor-bearing system using a hybrid method to compute the solutions of optimization problem. The present hybrid algorithm namely Enhanced Artificial Life Algorithm(EALA), is a synthesis of an artificial life algorithm(ALA) and the random tabu search(R-tabu) method. We applied EALA to the optimum design of rotor-shaft system supported by the floating ring journal bearings. we will propose the optimum shape of rotor, position and shape of bearings. Through this study, we investigate the reliability and usefulness of EALA.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.768-769
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• 2008

This paper examines an design of double-barrier rotor structure for improving the efficiency performance in a single-phase line-start permanent magnet(LSPM) motor. By utilizing the advantages of double-barrier rotor design that by increasing reluctance torque generation to compensate magnet torque production, the copper loss reduction is achieved. The optimal approach of response surface methodogy(RSM) is performed for determining a optimum double-barrier rotor structure. The improving of efficiency performance is confirmed by finite element method(FEM) and test.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.669-670
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• 2015

In this paper, rotor design modification of a novel proposed machine termed the Axial Flux Doubly Fed Reluctance Machine (AF-BDFRM) is studied. The main potential advantage of AF-BDFRM is that it has larger torque and power density compared to radial flux-BDFRM. However, with the general rotor pole shape, this machine output back EMF has high THD % and high cogging torque. This paper studies the rotor design modification in the proposed AF-BDFRM to reduce the THD % in inducedd back EMF and cogging torque. Also the transient 3D finite element analysis (FEA) optimization of initial design is presented.

• Journal of Wind Energy
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• v.5 no.1
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• pp.43-49
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• 2014

Primarily, tower loads of a wind turbine arise from aerodynamic effect and a top head mass. But sometime asymmetric loads of rotor also affect on the tower loads. Especially ice formation on two blades out of three causes the asymmetric loads, because the ice formation on blades lead to large rotating mass imbalance. This rotating mass imbalance of rotor affects tower fatigue loads. So design load cases of ice formation on blade should be considered in the fatigue design loads of the tower according to GL guideline 2010. This paper describes the change of tower fatigue loads following increase of tower height in the condition of ice formation. Finally, the optimal operation strategy is examined in order to reduce tower fatigue design loads.