• Journal of Power System Engineering
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• v.15 no.4
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• pp.65-74
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• 2011

이 논문은 비선형 시스템에 대해 bilinear 강인제어기를 설계하는 새로운 방법을 제시한다. 이 설계방법은 골칫거리인 비선형 영향을 나타내는 무거운 질량을 가지고 진동하는 시스템을 제어하기 위한 새로운 대안이고 진전된 방법이다. 이 설계 과정에, hydrostatic 구동기로 구동되는 킬(용골)이 주어진다. 첫 단계로 킬은 물리적으로 여러 한정된 질량으로 모델화된다. 물리적 모델에 근거한 수학적인 모델을 유도하는 방법은 해밀턴 원리를 적용한 유한요소법을 사용하였다. 즉, 수학적 모델은 여러 서브시스템으로 구성된다. 이것은 주어진 물리적인 시스템에 대해 기준이 되는 시스템이다. 회전하는 구동기에 대한 물리적 모델에 근거하여, 과도 거동은 구동기의 베어링에서 측정되는 운동 현상으로부터 유도된다. 물리적인 시스템은 bilinear 시스템으로 구성하였다. 이 시스템에 근거하여, 요트 킬의 거동을 제어하도록 bilinear 관측기를 설계한다. 구동기의 속도, 토크, 밸브에서의 유량 등이 관측기를 구성하는데 필요한 데이터들이다. 시뮬레이션 결과에 의하면 비선형성에 대한 추정과 보상을 통하여 무거운 질량을 갖는 회전축에 대한 위치와 힘을 제어하는 설계에 유용한 접근법임이 증명되었다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.973_974
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• 2009

본 연구는 영구자석 AC 동기전동기의 초기 기동제어에 대하여 연구하였다. 회전자 위치 검출용 센서는 홀센서를 사용하였고 전동기 운전을 벡터제어를 사용하기 위해 전동기가 정지된 상태에서 홀센서 신호에 따른 회전자 위치를 계산하였다. 견인전동기가 주행저항 보다 큰 견인력을 내기 위해 전동기를 BLDC로 기동한 후 안정적 운전을 위해서 벡터제어로 전환하였다.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.586-589
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• 2001

In Case of High speed PM machines with surface-mounted magnet. A rare-earth PM with high remanence flux density is used on the rotor. Therefore, It is very difficult to adhesion and assemble PM on the surface of rotor, because of very repulsive force between magnets. So, for solving this problem, rotor with surface-mounted magnet is wholly magnetized after mounting magnetic-material on the surface. In this paper, In order to Magnetize rotor with surface-mounted PM, magnetizing machine is designed, analyzed and simulated for large PM machines using the 1dimensional analytical method and 2dimensional finite element method. (20-FEM).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.215-218
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• 2003

In this study, a performance model of the Smart UAV propulsion system with ducts, tip jets and variable main nozzle, which has flight capability of the rotary wing mode for the take-off/landing and low speed forward flight as well as the fixed wing mode for high speed forward flight, has been newly developed. With the proposed model, steady-state performance analysis was performed at various flight modes and conditions, such as rotary wing mode, fixed wing mode, compound wing, mode altitude and flight speed.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.145-146
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• 2010

A moment redistribution method was developed for earthquake design of reinforced concrete moment-resisting frames. For a frame designed with strong column-weak beam, the moment redistribution mechanism was investigated. Based on the result, the relationship between redistributed moment and plastic rotation in plastic hinges was established. By using the relationship, we developed a method for the evaluation of plastic rotations during the moment redistribution, addressing the effects of various design parameters including member stiffness, load condition, and plastic mechanism of structure.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.36-44
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• 2000

The flow at the impeller exit is important to validate engineering design and numerical analysis of pumps. We installed axisymmetric collector instead of the volute casing, so there is no interaction between the impeller and casing. A hot-film probe and a high response pressure transducer are used to investigate the flow at impeller exit and vaneless diffuser region for design and off design flow rate. For a single suction centrifugal pump of low specific speed, the flow field such as velocity, flow angle, and total pressure are measured by traversing the probe across the vaneless diffuser. These data can be used for performance prediction, design, and numerical analysis of pumps.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.5
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• pp.118-123
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• 2004

The compressor has one of important roles in refrigeration cycle and it determines refrigeration efficiency and quality This paper aims to monitor rotary compressors for room air conditioners by using Acoustic Emission(AE) technique. The reliability of rotary compressors has been evaluated through visual inspection on them after long term test. This paper describes methods for acquisition and processing AE raw signal to monitor the state of rotary compressor. A detecting method of abnormal compressor in real time is suggested and special-purpose monitoring system which can be applied to automatic manufacturing line is developed using one-chip microprocessor at low cost.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.250-251
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• 2000

모드록킹된 광섬유 레이저 자이로스코프(ML-FLaG)$^{(1)}$ 는 일반 거울과 Sagnac 루프 거울로 이루어진 공진기 안에 이득 매질이 포함된 광섬유 레이저의 형태를 가진다. Sagnac 루프 거울을 서로 반대 방향으로 진행하는 두 빛 사이의 위상차를 변조시키면 루프 거울의 반사율이 변조되는데, 여기서 위상 변조 주파수를 공진기의 종모드 간격과 일치시키면 공진기 왕복 주기에 두 개의 펄스가 들어가는 모드록킹된 펄스열을 얻을 수 있다. 이 두 펄스 사이의 시간 간격은 회전율에 따라서 변하기 때문에, 두 펄스 사이의 시간 간격 변화를 측정하면 회전 각속도를 알아낼 수 있다. (중략)

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.7
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• pp.1709-1719
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• 1995

The primary objective of the paper is to obtain the basic information of the natural convection of a stratified with various parametric conditions related to rotating speed, temperature and concentration gradient. For the purpose of it, experiments are performed in a stably stratified salt-water solution with lateral heating in a stationary or rotating annulus. The experiment covers the ranges of Ar=2, Le=100, R $a_{\ta}$=2 10$^{5}$ and Ta=0, 10$^{5}$ - 2.5*10$^{8}$ . Many interesting flow phenomena are observed and rotation effects are examined. Particularly as Taylor number increases (rotation increases) at a given R $a_{\ta}$, the generation of rolls at hot wall is inhibited and the formation and merging process of layers are delayed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.328-332
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• 1996

The compressor is one of important elements in refrigerator cycle and play an important role of refrigeration efficiency and quality. Therefore it is very important to monitor state of normal and abnormal compressor. In this research, technic of AE is used for monitoring abnormal rotary compressor and an AE parameter which is a most proper parameter to monitor the abnormal state of compressor is determined by signal processing, Finally, the monitoring result of rotary compressor is agreement with the result of life test.