• International Journal of Precision Engineering and Manufacturing
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• v.7 no.2
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• pp.56-59
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• 2006

A vibrational model of powder transfer equipment based on the lumped parameter method was developed, in which the operating motion consists of surging, bouncing, and pitching. After decoupling the equation of motion, the vibrational excitation source of the pitching motion was removed. So the designers are able to plan the optimum design to adjust the motion trajectory of the powder transfer equipment. That is, a procedure to adjust the motion trajectory of powder transfer equipment by changing design specifications such as the installation position, the direction of the motor, the driving speed, the mass unbalance, the stiffness coefficient, and the installation position of the support spring, is presented in this paper. The powder transfer equipment manufactured according to the results of this study did not suffer fatigue destruction, since the maximum stress on the basket structure was sufficiently small.

• Journal of Ocean Engineering and Technology
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• v.19 no.2 s.63
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• pp.60-66
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• 2005

This paper investigates the relationship between the fleet-angle of the hoisting rope and the swaying and pitching angles of a cargo in container cranes. It is found that for a given disturbance, when the fleet-angle is large, the sway Angle becomes smaller, but the pitching angle becomes larger. Therefore, for a quick suppression of a sway motion, it is desirable to have a large fleet-angle. The compatibility and bifurcation conditions, regarding instability, are characterized.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.10
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• pp.2664-2674
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• 1994

Drag, lift, and pitching moment measurements have been made on a range of slanted-base ogive cylinders, using the KANOMAX wind tunnel and balance system. Test Reynolds numbers(based on model maximum diameter) varied from $0.54{\times}10^{5}{\;}to{\;}1.56{\times}10^{5}$. Crossflow velocity maesurement was conducted by 5-hole pitot tube at $Re_{D}=1.46{\times}10^{5}$. For two base angle $({\theta}=30$ and 45 deg.), aerodynamic forces and moment were measured with increasing angle of attack(0~30 deg.). Two types of wake flow were observed, a quasisymetric turbulent closure or a longitudinal vortex flow. Aerodynamic characteristics differ dramatically between the two wake types. It was found that the drag, lift and pitching moment coefficients increased with increasing angle of attack.

• Korean Journal of Applied Biomechanics
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• v.17 no.4
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• pp.127-139
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• 2007

The purpose of this study was to examine the pitching ability of baseball player by analysing the effect of elastic resistance exercise and pilates exercise on EMG. Five out of currently active highschool baseball player performed 5 times a week of elastic resistance exercise and pilates for 8 weeks, each for 100 minutes. They demonstrated significant increase in EMG after 8 weeks of exercise. Especially, in extensor carpi radialis brevis and flexor carpi radialis of fore arm, they demonstrated significant increase of inning figure after exercise. These results suggested that elastic resistance exercise and pilates exercise can improve pitching ability of baseball player according to inning.

• International Journal of Aeronautical and Space Sciences
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• v.2 no.2
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• pp.28-38
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• 2001

A numerical method for the assessment and correction of tunnel wall interference effects on forced-oscillation testing is presented. The method is based on the wall pressure signature method using computed wall pressure distributions. The wall pressure field is computed using unsteady three-dimensional full Navier-Stokes solver for a 70-degree pitching delta wing in a wind tunnel. Approximately-factorized alternate direction implicit (AF-ADI) scheme is advanced in time by solving block tri-diagonal matrices. The algebraic Baldwin-Lomax turbulence, model is included to simulate the turbulent flow effect. Also, dual time sub-iteration with, local, time stepping is implemented to improve the convergence. The computed wall pressure field is then imposed as boundary conditions for Euler re-simulation to obtain the interference flow field. The static computation shows good agreement with experiments. The dynamic computation demonstrates reasonable physical phenomena with a good convergence history. The effects of the tunnel wall in upwash and blockage are analyzed using the computed interference flow field for several reduced frequencies and amplitudes. The corrected results by pressure signature method agree well with the results of free air conditions.

• Design & Manufacturing
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• v.2 no.4
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• pp.11-15
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• 2008

In the sheet metal forming using a high speed press machine, driving device, such as crank, link, and knuckle mechanism, has to be designed in consideration of impact at a moment when press die contact with material, because the impact affects a dimensional accuracy of products and a life span of press die. In this study, dynamic analysis was performed using numerical simulation in order to verify the impact reduction effect for proposed double knuckle mechanism by estimating rolling and pitching moment of slide.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.569-574
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• 2015

지난 수십 년간 유체역학적인 관점에서 곤충이나 새의 움직임을 모방하기 위해 진동하는 익형(pitching airfoil)과 동적 실속에 관한 많은 연구가 진행되어 왔다. 그러나 유동박리가 일어나지 않는 범위 내에서 진동하는 익형의 특성에 대한 연구는 보기 드물다. 또한 기존의 유동박리가 일어나지 않는 영역에서 익형의 진동 현상에 대해 수행된 연구는 수중과 같이 낮은 레이놀즈수에서 수렴되었기 때문에, 공기 중과 같이 높은 레이놀즈수에서 유동현상과 다른 특성을 보여주고 있을 수 있다. 따라서 본 연구는 높은 레이놀즈수에서의 다양한 환산 진동수, 받음각진폭, 익형에 따른 공력특성을 분석하였다. 그 결과, 익형의 진동으로 인한 양력계수의 차이는 작음을 알 수 있었다. 그러나 높은 환산 진동수에서 익형의 항력계수가 감소하는 경향이 나타나며, 이로 인해 높은 환산 진동수에서 수치적으로 추력이 발생할 수 있음을 확인하였다.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.650-653
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• 1998

In this paper, when we control Elevation Angle and Azimuth Angle of Antenna, intend to implement sensor system for stabilization control of antenna pedestral system because of wind in land, wave and external disturbances such as rolling, pitching, and yawing. Therefore, this sensor system is consist of Tilt Sensor for measuring absolute angle of roll ing and pitching, Level Rate Sensor, Cross Level Rate Sensor, Azimuth Rate Sensor for controlling short_term azimuth angle and Flux Gate Sensor for measuring long_term azimuth angle.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.6
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• pp.1043-1050
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• 2010

This paper examined the probabilistic load analysis for the tailplane during pitching maneuvering in the conceptual aircraft design phase. The flight load analysis based on the probabilistic distribution of design variables are compared with the results of the deterministic analysis. Two forms of variable distribution are used in this paper. One is standard normal distribution, the other distribution is calculated from the results of short-period longitudinal equation of aircraft motion. The influence of the distribution parameter on the probabilistic load analysis was investigated and the significant design variables that have an impact on the mean and variance of probabilistic load were identified. The comparison indicates that probabilistic load analysis provides more reliable probabilistic load distribution for the structural design than the traditional deterministic analysis.

• Interaction and multiscale mechanics
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• v.1 no.3
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• pp.381-396
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• 2008

The aerostatic instability of cable-supported bridges is studied, with emphasis placed on modeling of the geometric nonlinear effects of various components of cable-supported bridges. Two-node catenary cable elements, which are more rational than truss elements, are adopted for simulating cables with large or small sags. Aerostatic loads are expressed in terms of the mean drag, lift and pitching moment coefficients. The geometric nonlinear analysis is performed with the dead loads and wind loads applied in two stages. The critical wind velocity for aerostatic instability is obtained as the condition when the pitching angle of the bridge deck becomes unbounded. Unlike those existing in the literature, each intermediate step of the incremental-iterative procedure is clearly given and interpreted. As such, the solutions obtained for the bridges are believed to be more rational than existing ones. Comparisons and discussions are given for the examples studied.