• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.804-810
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• 2004

Tilting train can pass curve at higher speed without affecting passenger comfort by tilting Carbody. But the centrifugal force proportional to square of velocity increases the track lateral force. This is the one of the problems to be solved when applying tilting train. The one countermeasure we selected the light weight design by applying distributed traction EMU system and light weight materials such as FRP. The other countermeasure was to adopt steering bogie concept in order to reduce the guiding force on Curve track. This paper describes the design study of self steering mechanism applied to the Bogie for 180 km/h Korean Tilting Train(TTX), which was done as a part of the Korean National R&D project.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.120-123
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• 2000

It is well known, for many years, that deep drawability can be improved by applying variable blank holding force. To apply variable blank holding force during cup during, we set up pressure controlling system on experimental hydraulic press, and the pressure control system is often called NC(Numerically Controlled) cushion system Using the NC cushion system we compared the drawability of square steel cups with NC cushion and that with conventional cushion. The results show drawability is greatly improved when the pressure control curve is designed in a S-shaped curve. This paper includes design details of the NC cushion system and experimental analysis of drawability with experimental NC cushion system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.18-20
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• 2002

In this paper, various forces generated in the Gas Circuit Breaker(GCB) such as operating force, repulsive force, spring force, and dashpot force are analyzed with the fluid properties and the mechanical structure. The operation of GCB can be understood. A stroke curve from the result of simulation is compared with experimental one.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.725-726
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• 2012

• 한국운동역학회지
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• 제27권2호
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• pp.141-147
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• 2017

Objective: We obtained force-displacement curves for countermovement jumps of multiple heights and examined the effect of an arm swing on changes in vertical jumping strategy. Countermovement jumps with hands on hips (Condition 1) and with an arm swing (Condition 2) were evaluated to investigate the mechanical effect of the arm movement on standing vertical jumps. We hypothesized that the ground reaction force (GRF) and/or center of mass (CoM) motion resulting from the countermovement action would significantly change depending on the use of an arm swing. Method: Eight healthy young subjects jumped straight up to five different levels ranging from approximately 10% (~25 cm) to 35% (~55 cm) of their body heights. Each subject performed five sets of jumps to five randomly ordered vertical elevations in each condition. For comparison of the two jumping strategies, the characteristics of the boundary point on the force-displacement curve, corresponding to the vertical GRF and the CoM displacement at the end of the countermovement action, were investigated to understand the role of arm movement. Results: Based on the comparison between the two conditions (with and without an arm swing), the subjects were grouped into type A and type B depending on the change observed in the boundary point across the five different jump heights. For both types (type A and type B) of vertical jumps, the initial vertical force at the start of push-off significantly changed when the subjects employed arm movement. Conclusion: The findings may imply that the jumping strategy does change with the inclusion of an arm swing, predominantly to modulate the vertical force advantage (i.e., the difference between the vertical force at the start of push-off and the body weight).

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.597-599
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• 1995

We have analyzed the dielectrophoretic(DEP) force on a cell in a micro planar electrode structure. We fabricate a micro planar electrode structure using micro machining technology and measure the motion of a cell that is accelerated by DEP force. DEP force on a cell is calculated by curve fitting the motion of a cell. Radish and yeast are used for the experiment. In case of radish, DEP force is increased as the voltage and the frequency is increased, and in case of yeast, DEP force is increased only as the voltage is increased DEP force on a yeast does not vary when the frequency varies from 1 MHz to 3 MHz. The result will be helpful to the manipulation of cells using DEP force.

• Journal of Mechanical Science and Technology
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• 제18권10호
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• pp.1700-1711
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• 2004

Piston friction is one of the important but complicated sources of energy loss of a hydraulic axial piston machine. In this paper, two formulas are derived for estimating instantaneous piston friction force and average piston friction moment loss. The derived formula can be applicable for piston guides with or without bushing as well as for axial piston machines of motoring and pumping operations. Through the formula derivation, a typical curve shape of friction force found from several experimental measurements during one revolution of a machine is clearly explained in this paper that it is mainly due to the equivalent friction coefficient dependent on its angular position. Stribeck curve effect can easily be incorporated into the formula by replacing outer and inner friction coefficients at both edges of a piston with the coefficient given by Manring (1999) considering mixed/boundary lubrication effects. Novel feature of the derived formula is that it is represented only by physical dimensions of a machine, hence it allows to estimate the piston friction force and loss moment of a machine without hardworking experimental test.

• Nuclear Engineering and Technology
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• 제54권9호
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• pp.3205-3214
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• 2022

The aim of this study is to provide a clear and accessible method to obtain accurate true-stress strain data, and to extend the limited material data beyond the ultimate tensile strength (UTS) for AISI 304L. AISI 304L is used for the outer construction for some types of nuclear transport packages, due to its post-yield ductility and high failure strain. Material data for AISI 304L beyond UTS is limited throughout literature. 3D digital image correlation (DIC) was used during a series of uniaxial tensile experiments. Direct method extracted data such as true strain and instantaneous cross-sectional area throughout testing such that the true stress-strain response of the material up to failure could be created. Post processing of the DIC data has a considerable effect on the accuracy of the true stress-strain data produced. Influence of subset size and smoothing of data was investigated by using finite element analysis to inverse model the force displacement response in order to determine the true stress strain curve. The FE force displacement response was iteratively adapted, using subset size and smoothing of the DIC data. Results were validated by matching the force displacement response for the FE model and the experimental force displacement curve.

• 대한기계학회논문집A
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• 제38권3호
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• pp.329-335
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• 2014

U 자형 전자석 하나로 부상력과 안내력을 동시에 얻는 중 저속 자기부상열차는 안내제어기 없이 곡선을 주행한다. 때문에 곡선, 특히 곡률반경이 매우 작은 곡선 주행 시에 차량이 레일과 물리적 접촉을 방지하기 위해서는 곡선형상의 결정이 세심하게 이루어져야 한다. 특히 완화곡선의 형상이 중요하다. 본 논문에서는 완화곡선 선로를 구성하는 형상 매개변수들의 차량 안내 성능에의 영향도를 분석하는데 목적이 있다. 이를 위하여 차량, 전자석, 부상제어기, 곡선가이드웨이가 통합된 3 차원 자기부상열차 다물체 동역학 모델을 개발하였고, 개발된 모델을 이용하여 곡선형상을 구성하는 매개변수 연구를 수행하였다. 연구 결과는 곡선형상의 결정이나 차량의 대차구조를 설계하는데 이용이 가능하다고 할 수 있다.

• 한국지반공학회논문집
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• 제34권7호
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• pp.51-58
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• 2018

본 연구에서는 하중 조건에 따른 지반-말뚝 상호작용 시스템의 거동 차이를 분석하기 위해 일련의 원심모형 실험을 수행하였다. 정적 하중 조건의 경우, 말뚝 직경의 50% 수준까지 변위제어를 통해 하중을 재하하였으며, 지진 하중 조건의 경우 0.1g~0.4g 수준으로 1Hz 정현파를 가진하였다. 실험 결과로부터 얻은 정적 및 동적 p-y 곡선을 API p-y 곡선과 비교한 결과, API p-y 곡선과 정적 하중조건에서의 실험 p-y 곡선은 최대 지반반력 값이 20% 이내의 오차를 보인 반면, 동적 하중 조건에서의 실험 p-y 곡선과는 최대 지반반력 값이 5배 이상 차이가 발생하였다. 이는 등가정적 해석에서 기존 API p-y 곡선을 적용할 경우 비선형 영역에서 지반 반력을 크게 과소평가하며 보수적 설계를 야기할 수 있음을 의미한다.