• 대한기계학회논문집
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• 제5권4호
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• pp.293-302
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• 1981

In this paper, the stability of a flexible missle, idealized as a free-free beam, is evaluated by using the finite element method. For the study, heavy machinery part is modeled as a concentrated mass and the thrust, which is controlled by a feedback sensor located at a predetermined position, is considered as a constant follower force. The aerodynamic forces, the structural damping, the cross sectional variation servo lag effect are neglected in this study. With unconstrained variational principle, the finite element method is applied to the nondimensionalized beam eqution. The matrix eigenvalue equation is obtained and the eigenvalues are calculated by a computer for the stability analysis. The stability is evaluated by the inspection of the eigenvalues are calculated by a computer for the stabilith analysis. The stabilith is evaluated by the inspection of the eigenvalues of the problem. For the study, the behaviors of the eigenvalues at various thrusts and the effects of the magnitudes and positions of the concentrated mass and directional control constant are analyzed.

• 한국소음진동공학회논문집
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• 제11권9호
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• pp.398-405
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• 2001

The maximum and mean indicated pressure of two stroke low speed diesel engine has been continuously increased with a view of increasing engine power and also reducing fuel consumption. As a result, axial excitation has been increased comparing to that of the previous one. So the axial vibration damper in standard one is applied to all two stroke low speed diesel engine at the free end of crankshaft. Though many studies were carried out for marine use, few has been made for diesel power plant because there was little demand for power plant. Nowadays, diesel engine is much to be used for many benefits. In this paper, the optimum design of axial vibration on the 65 kW diesel power plant with tow 9K80MC-S engines of 9 cylinders was carried out. And the axial-torsional coupled vibration of this shafting system is identified by theoretical analysis and vibration measurement.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.2011-2014
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• 2008

A linear induction motor for urban railway transit is accompanied with the end-effect and large air-gap comparing with a rotary induction motor. These cause amount of difference between simulation results and experiments. In order to figure out the difference, experiments based on a real-scale test bed are indispensable, however building a test-line and a test vehicle is so difficult that authors are going to make a small-scale model and simulate it for comparison. In this paper, A rotary-type small-scale model of a linear induction motor is designed. Thrust and normal force of the model have been analyzed with the variation of frequency and speed by using a Finite Element Method(FEM).

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.271-276
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• 2001

Conventional clonoscope is semiflexible tube that should be manipulated by operator for inspection and treatment. Therefore, it sometimes causes pain for the patient and even perforation to the wall of colon if a surgeon is not well trained. For safe colonoscopy, self-propelling robots with inchworm locomotion are studied. But, inchworm locomotion has some problems in adaptiveness to the variation of colon diameter. In this paper, we propose novel locomotive mechanism which can move in the colon without any external assistance. It has several cams that have constant phase difference each other and located along the centerline of the mechanism. This mechanism could realize the robotic endoscope which has continuous and smooth thrust force.

• 한국항공우주학회지
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• 제41권1호
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• pp.31-39
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• 2013

본 논문에서는 고정익항공기와 회전익 항공기의 장점을 결합시킨 신개념 복합형 무인항공기인 QTW(Quad Tilt Wing)의 종축 동특성을 연구한 결과를 기술하였다. 설계된 QTW 무인항공기는 Tandem Wing 형상을 가지며 각 주익의 끝단에는 프로펠러를 구동하는 모터를 장착하였다. 비행역학적 분석을 위해 모멘텀 이론을 이용해 추력을 계산하였으며, 틸트 각도에 따른 프로펠러의 Slip stream에 의한 양력과 항력을 고려한 비선형 모델링을 구축하였다. 또한 트림분석을 통해 설계된 비행체가 적절한 비행속도 대비 틸팅각을 가짐을 보여주었으며, 각 트림 점에서의 성분별 힘을 분석하였다. 각 비행 모드의 선형모델 고유치 분석하여 동적 특성을 분석하였으며 고정익모드로 전환됨에 따라 안정한 부분으로 극점이 이동함을 확인하였다.