• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.698_699
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• 2009

본 논문은 정적 편심과 회전자 도체 봉 파손에 대해서 각각 특성 해석을 한 후, 두 고장이 복합된 상태를 특성 해석하였다. 해석 대상 전동기는 coupled magnetic circuits 방법으로 모델링 하고, 시뮬레이션하였다. 특성 해석에 필요한 중요 파라미터인 인덕턴스는 winding function 이론으로 계산하였다. 시뮬레이션 결과 중에서 고정자 전류를 전류 신호 분석 기술로 특성 해석을 하였다. 특성 해석 결과에서 고장 상태가 변하면 특정 주파수의 크기가 변하는 것을 알 수 있었다. 복합 고장에서는 정적 편심은 아래쪽 측 대역 성분의 크기를 증가시키고, 회전자 도체 봉 파손은 기본 특이 주파수 주변에 기생 성분을 만드는 것을 알 수 있었다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.837-842
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• 2007

Information storage devices using disks have a disk vibration at the frequency which is equivalent to the disk rotational speed. They also have a track vibration due to the disk eccentricity at the same frequency. In near field recording systems, the former affects the air-gap servo and the latter affects the tracking servo. In this paper, we introduce a novel control algorithm based on the internal model principle to both servos. A controller block designed by the principle is connected to the base lead-lag type compensator in parallel in order to cancel the repeatable run-out due to the disk vibration or eccentricity. Simulation and practical application of the algorithm on a near field recording system show good servo performance.

• Journal of Korean Society of Steel Construction
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• v.11 no.1 s.38
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• pp.89-98
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• 1999

The objective of this paper is to investigate the structural behavior of concrete filled steel tubular columns subjected to eccentric load. With experiment and analytical study, the buckling behavior of columns is investigated and compared with each other to the view of main parameters. Appling foreign standards in the experimental results, we suggested new strength formula of concrete-filled steel tubular columns. The parameters are slenderness, eccentric ratio, and concrete filled or not. The experiment are carried out by simple loading.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2613-2615
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• 2004

본 논문에서는 광학 디스크 기기의 주기적인 외란인 편심 보상을 위해 웨이블릿 신경 회로망 기반 외란 모델로 구성된 순방향 오차 제거(feedforward error rejection) 방법을 제안한다. 신호 모델링 방법으로 사용되어진 신경 회로망 모델의 단점인 실시간 처리 능력 및 국부 최소치로의 가능성 등을 극복하며 주파수와 시간 영역에서의 우수한 신호 해석 능력을 가진 웨이블릿 변환의 장점을 가진 웨이블릿 신경 회로망을 이용하여 디스크의 외란을 모델링 한다. 웨이블릿 신경회로망은 경사 강하법 (gradient descent method)을 이용하여 학습하며, 본 논문에서 제안한 방법의 효율성을 검증하기 위해 실제 광학 디스크 기기의 외란 데이터를 이용한 컴퓨터 모의 실험을 수행한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2475-2482
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• 2002

The measurement of residual stresses by the hole-drilling method has been commonly used to evaluate residual stresses in structural members. In this method, eccentricity can usually occur between the hole center and rosette gage center. In this study, the error due to the hole eccentricity is compensated using the neural network. The neural network has trained training examples of normalized eccentricity, eccentric direction and direction of maximum stress at eccentric case using backpropagation learning process. The trained neural network could compensated the error of measured residual stress in experiments with hole eccentricity. The proposed neural network is very useful for compensation of the error due to hole eccentricity in hole-drilling method.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.412-418
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• 2001

The measurement of residual stresses by the hole-drilling method has been commonly used to evaluate residual stresses in structural members. In this method, eccentricity can usually occur between the hole center and rosette gage center. In this study, the error due to the hole eccentricity is corrected using the neural network. The neural network has trained training examples of normalized eccentricity, eccentric direction and direction of maximum stress at eccentric case using backpropagation learning process. The trained neural network could corrected the error of measured residual stress in experiments with hole eccentricity. The proposed neural network is very useful for correction of the error due to hole eccentricity in hole-drilling method.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.1
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• pp.50-55
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• 1986

Characteristics of the flow and heat transfer in a channel of 37 rods are investigated numerically. The flow is taken to be a fully developed incompressible laminar flow and it has an uniform temperature profile at the inlet and flows down through the channel of constant wall temperature. A boundary-fitted coordinate system is used for the complex geometry. Calculation is initiated by calculating the developed flow profile and then proceeds to temperature development. Through the calculation the details of the flow and temperature distribution characteristics are found, and discussion is made on the mechanism of the transport phenomena in the complex geometry in terms of wall shear stress distribution, non-dimensionalized velocity, friction factor, Nusselt number distribution, Reynolds number, and porosity. Also the effects of the eccentricity in rod configuration are analyzed and its importance is emphasized.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.707-708
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• 2002

Catheters are used to measure translesional pressure gradients in the stenosed coronary arteries. Catheter insertions during coronary angioplasty cause flow obstructions. A narrowed flow cross section with catheter present effectively introduced a tighter stenosis than the enlarged residual stenoses after balloon angiplasty. In general, the form of stenoses are no uniform. Sometimes, these are occurred the irregularly eccentricity If the analyses are conducted for uniform stenosed artery, the results will be underestimated. Thus, in this study, three dimensional computer simulations are conducted to investigate the flow blockage effects due to the catheter insertion during the coronary angioplasty. The results for the eccentric stenosed artery are compared with those of the concentric stenosed artery.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.8 s.179
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• pp.2059-2064
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• 2000

The measurement of residual stresses by the hole-drilling method has been commonly used to evaluate residual stresses in structural members. In this method, one of the source of error is due to the misalignment between the drilling hole and strain gage center. This paper presents a finite element analysis of the influence of such misalignment for the uniaxial residual stress field. The stress error increases proportionally to hole eccentricity. The correction equations which easily obtain the residual stress taking account of the hole eccentricity are derived. The stress error due to the hole eccentricity decreases by approximately one percent using this equations.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.1
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• pp.18-23
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• 1985

In the fracture mechanics, the determination of the stress intensity factor value is vital for the prediction of a material fracture behavior. So many data concerning to the S.I.F. have been presented by many investigations to meet endless requrement. In this paper, the stress intensity factors of a sheet with an eccentrically inclined crack subjected to the pure bending moment were investigated theoretically by using of the complex mapping function to determine the Muskelishvili's comlex stress functions. Moreover, the theoretical value was compared with the result obtained from photoelastic esperiment. As a result, it was confirmed that both values coincided with satisfactorily within the margin of 2-3% devition; The results theoretically derived are right.