• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.111-111
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• 2004

회전축계는 발전기의 터빈이나 가스터빈 그리고 항공기의 회전익, 선박, 자동차등 산업전반에 널리 사용되어지고 있다. 이러한 회전축계의 안정성 확보와 성능향상을 위해서는 정확한 동적 모델링이 필요하며 지금까지 많은 연구가 되어 왔다. 일반적으로 회전축계의 동특성 이론 모델은 회전관성, 자이로모멘트, 전단변형을 포함하는 티모센코 축 요소를 널리 사용하고 있으며, 많은 연구를 통해 그 유용성이 입증되어 왔다.(중략)

• The korean journal of orthodontics
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• v.28 no.1 s.66
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• pp.61-74
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• 1998

The Purpose of this study was to investigate the stress distribution and tooth displacement at the initial phase produced by 5 types of molar uprighting springs using finite element method. The three dimensional finite element model of lower dentition, bone and springs was composed of 5083 elements and 2071 nodes. The results were as follows: 1. In case of helical spring and root spring, intrusion of lower canine and first premolar were observed md distal tipping, translation and extrusion of lower second molar were observed. 2. In case of T-loop, modified T-loop and box loop, intrusion and distal translation of lower second premolar were observed, and the largest crown distal tipping and translation of lower second molar were observed in T-loop and the smallest were observed in box loop. 3. In case of T-loop with cinch-bact crown distal tipping and translation of lower second molar were decreased, but extrusion was also decreased. 4. With increase of activation in T-loop, mesial translation and won distal tipping of lower second molar were increased and edentulous space was closing, but distal translation of second premolar was also increased. 5. With increase of tip-back bend in T--loop, distal tipping and translation of lower second molar were increased, but extrusion was also increased more largely.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.407-410
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• 2011

본 연구에서는 탑승객의 안전과 국내 환경에 적합한 제동거리 확보를 위해 새로운 개념의 스프링을 사용한 제동장치를 설계하고자 한다. 새로운 제동장치에 사용되는 스프링은 변위에 따라 감쇠 성능 특성을변화시키는 Multi-Rate 변위 감응형 스프링을 최적화하여 적용하였다. 이를 위한 최적화 기법으로는 비선형 최적화 기법인 순차적 2차계획법(Sequential Quadratic Programming, SQP)을 사용하였으며 먼저 Ziprider의 운동을 제동거리와 제동시 발생하는 회전각의 관계로 표현 가능한 수치모델을 개발하였다. 또한 개발된 수치모델은 Matlab을 이용하여 코드화하고 그 결과를 RecurDyn과 비교 분석하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.832-835
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• 2005

The free vibration of tapered piles embedded in soil is investigated. The pile model is based on the Bernoulli-Euler beam theory and the soil is idealized as a Winkler model for mathematical simplicity. The governing differential equations for the free vibrations of such members are solved numerically. The square tapered piles with one free and the other hinged end with rotational spring are applied in numerical examples. The lowest two natural frequencies are obtained over a range of non-dimensional system parameters: the rotational spring parameter, the embedded ratio, the foundation parameter, the width ratio of the contact area and the section ratio.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.80-80
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• 2004

베어링리스 모터는 기존의 전동기와 자기베어링을 결합한 기술로 축 길이가 줄어들어 회전 속도를 높일 수 있으며 소형화가 가능하다는 장점이 있다(Fig. 1). 베어링리스 모터를 설계하기 위한 첫 번째 단계는 베어링리스 모터의 수학적 모델을 도출하는 것인데, 기존의 연구에서 부상용 전류와 부상력의 관계는 잘 정립되어 있다. 그러나, 회전자의 변위에 따른 부상력의 변화는 명확히 정의되어 있지 안다. 본 논문에서는 분산 자기 회로 이론을 이용하여 회전자의 움직임에 따른 부상력의 변화를 스프링계수의 형태로 모델링하였다.(중략)

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.528-531
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• 2009

본 연구에서는 두 스프링으로 지지된 강체가 회전하는 Timoshenko 축을 따라 이동할 때, 그 계의 동적응답 특성을 해석하였다. 운동방정식은 Hamilton의 원리에 따라 유도되었다. 유도된 운동방정식을 이용하여 주요 설계 파라미터 변화에 따른 응답특성을 해석하였다. 해석시 설계파라미터를 무차원 변수화 하여 속도비, 질량비, 회전수비 등 그 변화에 따른 응답특성을 비교 분석하였다.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.89-96
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• 1999

This paper presents the optimization design technique on the joint stiffness and section characteristic factors of chassis frame, by using beam and spring elements in a given design package. Two correction methods are used for the optimization design of chassis frame. First is the equivalent inertia of moment method in relation to the section characteristic factors of joint zones, which are thickness , width and height of frame channel section. Second is the rotational spring element with joint stiffness of joint zones. The CAE example shows that the relationship of section characteristic factors and joint stiffness can effectively be used in designing chassis frame. In this point, if static and dynamic targets are given, the joint-zone and section characteristic factors of chassis frame intended may be designed and defined by using beam and rotational spring elements.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.815-818
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• 2006

This paper deals with the free, in-plane vibrations of curved members with the translational(radial and tangential directions) and rotational springs at the ends. The governing differential equations for the circular curved member are solved numerically using the corresponding boundary conditions. The lowest three natural frequencies and the corresponding mode shapes are obtained over a range of non-dimensional system parameters: the subtended angle, the slenderness ratio, the translational spring stiffness, and the rotational spring stiffness.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.802-807
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• 2003

The purpose of this paper is to investigate the free vibration characteristics of tapered beams with translational and rotational springs and tip masses at the ends. The beam model is based on the classical Bernoulli-Euler beam theory. The governing differential equation for the free vibrations of linearly tapered beams is solved numerically using the corresponding boundary conditions. Numerical results are compared with existing solutions by other methods for cases in which they are available. The lowest three natural frequencies are calculated over a wide range of non-dimensional system parameters: the translational spring parameter, the rotational spring parameter, the mass ratio and the dimensionless mass moment of inertia.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.864-869
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• 2003

The purpose of this paper is to investigate the free vibration characteristics of tapered beams with translational and rotational springs and point masses at the ends. The beam model is based on the classical Bernoulli-Euler beam theory which neglects the effects of rotatory inertia and shear deformation. The governing differential equation for the free vibrations of linearly tapered beams is solved numerically using the corresponding boundary conditions. Numerical results are compared with existing solutions by other methods for cases in which they are available. The lowest four natural frequencies are calculated over a range of non-dimensional system parameters.