• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.968-973
• /
• 2003

Dynamic L/UL system has many merits, but it can develop an undesirable collision during dynamic loading process. In this paper, the dynamics of negative pressure pico slider during the loading process was investigated by numerical simulation. A simplified L/UL model for the suspension system was presented, and a simulation code was built to analyze the motion of the slider. A slider deigns have been simulated at various disk rotating speeds, skew angles of slider. By selection an optimal RPM and pre-skew angle, we can decrease the amount of collision and smoothen the loading process for a given slider-suspension design.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 1998.10a
• /
• pp.113-119
• /
• 1998

This study is focused on evaluation of the structural behavior of skewed bridge during earthquake. The variation of natural frequencies and the lateral forces at pier shoes by the skewness and the rotational effect about vertical axis of skewed bridge due to seismic activity are analytically evaluated and identified through case studies. For this purpose, the composite steel girder highway bridges are selected as case study models. The seismic analyses by response spectrum method and time history method are performed for the selected models. It has been recognized that the frequency of longitudinal model increased as the skew angle decreased, while the lateral mode frequency showed the opposite trends. When the skew angle decreased, longitudina seismic forces of the bridge at the pier were increased but decreased in transverse direction. And it also has been found that the skewed bridges of the case study models showed the rotational behavior about vertical axis due to motion of San Fernando earthquake at Pacoima Dam.

• Transactions of the Society of Information Storage Systems
• /
• v.2 no.2
• /
• pp.144-149
• /
• 2006

Dynamic L/UL(Load/Unload) system has many merits. but it may happen an undesirable collision during the dynamic loading process. In this paper, the dynamics of negative pressure pico-slider was investigated through numerical simulation during the loading process. A simplified L/UL model for the suspension system has been presented and a simulation code has been developed to analyze the motion of the slider. A slider design has been simulated at various disk rotating speeds, skew angles of slider. We can decrease the possibility of collision and smoothen the loading process for a given slider-suspension design by selection an optimal rpm and pre-skew angle.

• Steel and Composite Structures
• /
• v.28 no.4
• /
• pp.509-516
• /
• 2018

The differential quadrature (DQ) and teaching-learning based optimization (TLBO) methods are coupled to introduce a hybrid numerical method for maximizing fundamental natural frequency of laminated composite skew plates. The fiber(s) orientations are selected as design variable(s). The first-order shear deformation theory (FSDT) is used to obtain the governing equations of the plate. The equations of motion and the related boundary conditions are discretized in space domain by employing the DQ method. The discretized equations are transferred from the time domain into the frequency domain to obtain the fundamental natural frequency. Then, the DQ solution is coupled with the TLBO method to find the maximum frequency of the plate and its related optimum stacking sequences of the laminate. Convergence and applicability of the proposed method are shown and the optimum fundamental frequency parameter of the plates with different skew angle, boundary conditions, number of layers and aspect ratio are obtained. The obtained results can be used as a benchmark for further studies.

• Bulletin of the Korean Mathematical Society
• /
• v.53 no.5
• /
• pp.1411-1425
• /
• 2016

We provide a partial differential equation for European options on a stock whose price process follows a general geometric Riemannian Brownian motion. The existence and the uniqueness of solutions to the partial differential equation are investigated, and then an expression of the value for European options is obtained using the fundamental solution technique. Proper Riemannian metrics on the real number field can make the distribution of return rates of the stock induced by our model have the character of leptokurtosis and fat-tail; in addition, they can also explain option pricing bias and implied volatility smile (skew).

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.12
• /
• pp.1185-1191
• /
• 2011

The kinematic characteristics of cutting device significantly affects cutting performance in 2-dimensional elliptical vibration cutting(EVC) where the cutting tool cuts workpiece, traversing a micro-scale elliptical trajectory in a trochoidal motion. In this study, kinematical characteristics of EVC device constructed with two parallel stacked piezoelectric actuators were analytically modeled and compared with the experimental results. The EVC device was subjected to step and low-frequency(0.1 Hz) sinusoidal inputs to reveal only its kinematical displacement characteristics. Hysteresis in the motion of the device was observed in the thrust direction and distinctive skew of the major axis of the elliptical trajectory of the cutting tool was also noticed. Discrepancy in the voltage-to-displacement characteristics of the piezoelectric actuators was found to largely contribute to the skew of the major axis of the elliptical trajectory of the cutting tool. Analytical kinematical model predicted the cutting direction displacement within 10 % error in magnitude with no phase error, but in estimating the thrust direction displacement, it showed a $27^{\circ}$ of phase-lag compared with the measured displacement with no magnitude error.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.848-849
• /
• 2011

Rotating machines are using gears to change the rotary motion into the linear motion, on the other hand, linear motors have a accurate position control and excellent dynamic characteristics because of generating a thrust force directly. But the important problem, one of the linear motor is a high thrust force ripple. Thrust force ripple has a bad effect on the position accuracy and the dynamic characteristics, so it is necessary to reduce the thrust force ripple. Cogging is one of the cause that affect thrust force ripple. Cogging has some connection with the GCD between pole pitch and teeth pitch It is proposed method to reduce a thrust ripple of the linear motor that chamfering, skew, and so on. In this paper, the module phase set shift(MPSS) is used to reduce a thrust force ripple that has a similar effect to skew. And propose a method that reduce a thrust force ripple more by use of chamfering.

• Journal of Power System Engineering
• /
• v.14 no.4
• /
• pp.76-81
• /
• 2010

본 논문에서는 카메라를 이용하여 크레인 스프레더의 스큐모션을 계측하는 계측기법에 대해 고찰하고 있다. 계측장치는 트롤리에 설치한 카메라와 스프레더에 설치한 두 개의 랜드마크로 구성된다. 랜드마크를 이용하여 크레인 스프레더 흔들림과 상하위치를 검출하는 기법은 저자들이 이미 제안한 기술이며 실험을 통해 그 유용성을 검증하였다. 크레인 스프레더의 스큐모션 계측기법 또한 제안된 계측기법에 기초한 것으로 두 개의 랜드마크를 검출하여 템플릿 매칭기법으로 스큐모션을 계측할 수 있다. 스큐모션은 스프레더의 회전각도를 검출하여 계측해야 하는데 계측정도와 신뢰도는 정확한 템플릿매칭의 가능여부에 의존하게 된다. 즉, 랜드마크의 회전으로 매칭이 실패할 경우에는 정확한 회전각도를 검출할 수 없는 경우가 발생할 수 있게 된다. 따라서 본 논문에서는 랜드마크 회전에 따라 템플릿을 회전시키는 방법을 도입하여 템플릿매칭의 신뢰성과 계측정도를 개선하는 방법에 대해 연구하였다. 제안된 방법을 이용할 경우 템플릿매칭이 실패하는 경우가 없음을 실험을 통해 확인하였으며, 측정범위는 ${\pm}12^{\circ}$ 이고 이것은 크레인 스프레더의 스큐모션을 파악하고 제어하는데 충분한 정도의 범위이다.

• Structural Engineering and Mechanics
• /
• v.39 no.6
• /
• pp.861-875
• /
• 2011

The aim of the present article is to study the micropolar thermoelastic interactions in an infinite Kelvin-Voigt type viscoelastic thermally conducting plate. The coupled dynamic thermoelasticity and generalized theories of thermoelasticity, namely, Lord and Shulman's and Green and Lindsay's are employed by assuming the mechanical behaviour as dynamic to study the problem. The model has been simplified by using Helmholtz decomposition technique and the resulting equations have been solved by using variable separable method to obtain the secular equations in isolated mathematical conditions for homogeneous isotropic micropolar thermo-viscoelastic plate for symmetric and skew-symmetric wave modes. The dispersion curves, attenuation coefficients, amplitudes of stresses and temperature distribution for symmetric and skew-symmetric modes are computed numerically and presented graphically for a magnesium crystal.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.863-866
• /
• 2008

For the cost reduction in the fabrication of display panels, a reverse moving system was equipped to a compacted in-line wet etch/cleaning system. For the effect of the alternating movement of substrate on the wet etch process, ITO layers were etched in various moving modes of substrates and the results were compared and analyzed.