• Tribology and Lubricants
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• v.40 no.1
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• pp.8-16
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• 2024

This study conducts numerical modeling and eigen-analysis of a rod-fastened rotor, which is mainly used in aircraft gas turbine engines in which multiple disks are in contact through curvic coupling. Nayak's theory is adopted to calculate surface parameters measured from the tooth profile of the curvic coupling gear. Surface parameters are important design parameters for predicting the stiffness between contact surfaces. Based on the calculated surface parameters, elastoplastic contact analysis is performed according to the interference between two surfaces based on the Greenwood-Williamson model. The equivalent bending stiffness is predicted based on the shape and elastoplastic contact stiffness of the curvic coupling. An equation of motion of the rod-fastened rotor, including the bending stiffness of the curvic coupling, is developed. Methods for applying the bending stiffness of a curvic coupling to the equation of motion and for modeling the equation of motion of a rotor that includes both inner and outer rotors are introduced. Rotordynamic analysis is performed through one-dimensional finite element analysis, and each element is modeled based on Timoshenko beam theory. Changes in bending stiffness and the resultant critical speed change in accordance with the rod fastening force are predicted, and the corresponding mode shapes are analyzed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.1038-1043
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• 2002

The floating ring journal bearing is attraction for high-speed turbo machinery applications, including turbochargers and aircraft accessory equipment, because it is not only simple and easy to make and to replace in the field but also it seems to have adequate high speed stability characteristics. Therefore, an analysis method of dynamic properties of floating ring journal bearing is presented. The static equilibrium locus of inner film and outer film are calculated by using the impedance description. The equivalent stiffness and damping coefficients of floating ring journal bearing are composed by using the equilibrium of torque between inner film and outer film. Then, a stability analysis of turbocharger shaft system supported with floating ring journal bearing has been performed.

• Tribology and Lubricants
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• v.21 no.2
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• pp.53-62
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• 2005

In this study a general Galerkin FE lubrication analysis method was utilized to analyze the complex lubrication performance of a spiral groove seal having an additional inner circular groove, which was designed for a chemical process mixer operating at a low speed of the maximum 500 rpm. Equilibrium seal clearance analyses under varying outer pressure revealed that the seal maintains a certain levitation seal clearance under the outer pressure of more than about 1.5 bar, regardless of a rotating speed. Also, under the normal outer pressure of 11 bar, the axial stiffness of the seal was predicted to have a high value of more than 7.0 e + 07 N/m, regardless of a rotating speed and thereby, the seal is expected to maintain a stable thickness of lubrication film under a certain external excitation acting. A seal levitation test rig was designed and constructed. Experimental results at 500 rpm agreed well with analytical predictions and the applied lubrication analysis method was verified.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1353-1354
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• 2013

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.963-964
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• 2011

본 논문에서는 세탁기용 DD모터로 사용되고 있는 BLDC를 대신하여 외전형 Switched Reluctance Motor (SRM) 타입으로 세탁기의 부하에 따라 저속/고토크인 세탁모드, 고속/저토크인 탈수모드의 특징에 만족시키는 전동기를 설계한다. 이와 같은 특징을 고려하여 외전형 SRM의 극 조합을 12/8, 18/12, 30/20, 36/24에 대해 설계하고 FEM을 통해서 특성을 해석한다. 이 중 세탁기용 전동기에 알맞은 구조를 선정하고자한다.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.510-511
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• 2011

This paper has represented about the activated scheme the Honam regional wind power industry favorable products. The favorable products are the MW offshore wind system with Outer-rotor type PMSG-6 products, the 3MW offshore wind system with adatation type of west-south sea, and the hybrid generator system with wind turbine technology basis-2 products.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.400.2-400
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• 2002

Recently rotating machines have became high speed and high Power and light weight. Bearings are one of the main components which influence power loss and stability of rotating machines. Appropriate bearing should be selected with considering characteristics of rotating machine. Floating ring journal bearing(FIB) consists of an inner film and outer film, and possess high damping and stability. FJB has been for adopted into turbocharger for the high stability at high operating speed. (omitted)

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.11
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• pp.1383-1389
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• 2011

Gerotor-type volumetric displacement pumps are suitable for oil or water hydraulics. For this reason, many researchers have studied this topic. Gerotor pumps have been widely used in various fields. In this study, we designed a rotor profile based on an envelope of a family of curves. An analytic method for determining the volumetric displacement of the gerotor pump is verified by comparing a result obtained using CAD technology and an experimental result. Throughout the experiment, the flow rate performance was verified. In addition, we describe the design and volumetric displacement characteristics of the gerotor pump.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.2
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• pp.181-186
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• 2009

The objective of this study is ensuring safety of cabin when the blade impacts into a obstacle by verifying safety of the rotor mast and the transmission using impact loads calculated from the simulation. The rotor mast shall not fail and the transmission shall not be displaced into occupiable space when the main rotor composite blade impact into a 8 inch rigid cylinder in diameter on the outer 10% of the blade at operational rotor speed. To calculate the reaction loads at the spherical bearing and lead-lag damper, blade impact analysis was performed with FE model consist of composite blade, tree(or rigid cylinder) using elastic-plastic with damage material and several contact surfaces which were created to describe a progress of actual failure. Also, the reaction loads were investigated in change of blade rotation speed and pitch angle.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.101-103
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• 2006

외전형 유도전동기 모터는 내전형에 비해 소형화 및 경량화 시킬 수 있는 장점이 있다. 하지만 회전자와 고정자간의 공극사이에 이심률이 있을 때, 불균형 모멘트로 인한 토크 리플이 내 전형보다 더 크게 일어나는 단점이 있다. 이러한 토크리플은 모터의 정속적인 운전을 방해시킬 뿐만 아니라 불규칙한 출력토크로 인한 작동상의 오류를 초래한다. 본 논문에서는 의전형 모터에서 이심률에 따른 불균형력이 최소화 될 수 있는 슬롯 형태에 대해서 연구하기 위해, 전폐형, 반폐형, 개구형태의 3가지 슬롯 형태에 대한 특성을 비교 하였다. 개구형의 경우 슬롯 누설 리액턴스가 낮아져 토크 형성율이 매우 높아 높은 토크를 발생시킬 것을 예상 하였지만, 토크 리플에 따른 출력 감소로 오히려 출력토크가 감소할 뿐만 아니라 이심률 증가에 따른 불균형력 또한 매우 컸다. 이에 비해 전폐형태의 슬롯은 누설리엑턴스의 영향으로 토크 형성 자체는 10% 정도 저감 되었으나, 이심률 증가에 따른 분균형력이 가장 적어 의전형 모터에 가장 적함한 형태임을 알 수 있었다.