• Journal of the Korean Society for Precision Engineering
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• v.15 no.9
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• pp.175-181
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• 1998

The coil spring is used in the suspension of automotive vehicles and small omnibus. Recently, it can be adopted hardening type spring which spring constant is accompanied by increasing displacement to increase passenger comfortability. One of methods which assert this characteristic is cylindrical-taper section coil spring. In this paper we calculate ideal spring characteristic curve from the given vehicle conditions, and show the design method of the cylindrical-taper section coil spring.

• Restorative Dentistry and Endodontics
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• v.33 no.4
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• pp.323-331
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• 2008

Flexibility and fracture properties determine the performance of NiTi rotary instruments. The purpose of this study was to evaluate how geometrical differences between three NiTi instruments affect the deformation and stress distributions under bending and torsional conditions using finite element analysis. Three NiTi files (ProFile .06 / #30, F3 of ProTaper and ProTaper Universal) were scanned using a Micro-CT. The obtained structural geometries were meshed with linear, eight-noded hexahedral elements. The mechanical behavior (deformation and von Mises equivalent stress) of the three endodontic instruments were analyzed under four bending and rotational conditions using ABAQUS finite element analysis software. The nonlinear mechanical behavior of the NiTi was taken into account. The U-shaped cross sectional geometry of ProFile showed the highest flexibility of the three file models. The ProTaper, which has a convex triangular cross-section, was the most stiff file model. For the same deflection, the ProTaper required more force to reach the same deflection as the other models, and needed more torque than other models for the same amount of rotation. The highest von Mises stress value was found at the groove area in the cross-section of the ProTaper Universal. Under torsion, all files showed highest stresses at their groove area. The ProFile showed highest von Mises stress value under the same torsional moment while the ProTaper Universal showed the highest value under same rotational angle.

• Journal of Korean Association for Spatial Structures
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• v.7 no.5
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• pp.83-87
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• 2007

Elastic critical loads of sinusoidally tapered bars with simply supported ends are determined by finite element method. The parameters considered in the analysis are taper parameter (=a) and section property parameter (=m). The analysis result for the special case of porismatic bar (a=0) shows good agreement with the existing value. The changes of the critical load coefficients are expressed by an algebraic equation. The coefficients appearing in the equations are determined by regression technique. The critical loads coefficients estimated by the proposed equations reveal little errors when they are compared with those determined by finite element method.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.4
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• pp.338-346
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• 2013

Equations of motion of a rotating blade considering pre-twist angle, cross section taper and a concentrated mass are derived using the hybrid deformation variable modeling method. For the modeling of a concentrated mass which is located at an arbitrary position of the blade, a Dirac delta function is employed for the mass density function. The final equations for the vibration analysis are transformed into a dimensionless form using several dimensionless parameters. The effects of the dimensionless parameters on the vibration characteristics of the rotating blade are investigated through numerical analysis.

• Journal of the korean Society of Automotive Engineers
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• v.3 no.1
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• pp.38-45
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• 1981

In this paper, the natural frequencies of curved taper leaf springs using on vehicle suspension systems are studied. By applying the Castigliano's definition, Rayleigh's principle and Dunkerley's equation, new formulas defining the natural frequency of such shaped spring are derived. Numerical calculations are in very good agreement with experimental results on actual models. We found that the natural frequencies of curved taper spring are increased by 21-28% compared with the spring having same weight, span and curve but uniform section.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.2
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• pp.125-131
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• 2014

Winding is an integral operation in almost every roll-to-roll continuous process and center-winding is suitable and general scheme in the winding system. However, the internal stresses within center-wound rolls can cause damage such as buckling, spoking, cinching, etc. It is therefore necessary to analyze the relationship between taper tension in winding section and internal stress distribution within center-wound roll to prevent the winding failure. In this study, an optimal taper tension control method with parabolic taper tension profile for producing high quality wound roll was developed. The new logic was designed from analyzing the winding mechanism by using the stress model in center-wound rolls. The performance of the proposed taper tension profile was verified experimentally.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.877-881
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• 1996

승용차나 소형승합차에는 현가장치의 스프링으로 코일스프링을 많이 사용하고 있으며 최근 들어 승차감의 상을 위해 변위의 증가와 함께 스프링 정수가 증가하는 경화 특성 스프링(hardening type spring)을 많이 채택하고 있는데, 이 특성을 나타낼 수 있는 방법 중 하나가 등반경-테이퍼 소재의 코일스프링이다. 이 논문에서는 주어진 차량조건으로부터 이상적인 스프링 특성곡선을 계산하고 이 곡선을 분할하여 직선의 연결로 근사시켜 분할한 수만큼의 직선적 특성의 스프링으로 직렬 연결되어 있다고 가정하여 이 곡선에 근접된 특성을 가지는 등반경-테이퍼 소재 코일 스프링의 설계방법을 제시하고자 한다.

• Korean Journal of Computational Design and Engineering
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• v.6 no.3
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• pp.206-214
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• 2001

This paper describes the wire EDM (Electric Discharge Machining) CAM system considering a variable taper wire-cut and an unmanned wire EDM during the night. Wire EDM is applicable to all materials that are fairly good electrical conductors, including metals, alloys and most carbide. Thus it provides a relatively simple method for making holes of any desired cross section in materials that are too hard or brittle to be machined by most other methods. In this paper we classify variable taper wire-cut machining patterns and variable taper wire-cut geometries. Also we determine unmanned wire EDM patterns fur the productivity of wire EDM industry. Developed system consists of two modules: 1) Variable taper wire EDM module guarantees the length ratio machining function, the parametric ratio machining function and the marking function. 2) Unmanned wire EDM module guarantees the automatic wire EDM during the night. The proposed system has been tested in the fields and found to be a useful system.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.185-189
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• 2003

The purpose of this study is to obtain the optimal operating condition of conduction cooled taper shape high-temperature superconductor (HTS) current lead operated in current sharing mode. In our previous study, we discovered that the optimal operating condition of constant cross-section area HTS current lead is in the current sharing state, and in optimal condition, the temperature gradient at warm end is not zero. The analysis result of taper HTS current lead is quiet similar to the constant area HTS current lead. The minimum dissipation of taper HTS current lead is not influenced by taper angle, however the optimal operation condition is varied with taper angle.

• Journal of Aerospace System Engineering
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• v.12 no.6
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• pp.41-49
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• 2018

In this study, the theoretical dynamic characteristics of a thin-walled composite beam with a single-cell of chordwise asymmetric cross-section was studied. Mathematical modeling was done by considering the transverse shear effects, the warping restraint effects, the constant taper ratio in the longitudinal direction of the beam, and the geometrical cross-section ratio. The mass coefficients, stiffness coefficients, and Eigen frequencies of the selected section were investigated. In particular, the effects of the taper ratio and cross-section ratio of the model on the Eigen frequencies were analyzed and compared when the asymmetry of the section was considered and the warping function was not corrected.