• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.13 no.2
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• pp.209-218
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• 1995

It is important role that railway speed up plays in realizing an affluent society in future. Curved lines zone have crucial effects on the speed of train travel, at the curved lines zone, it requires to set cant and slack for safety running of train and comfortable ride of passengers, a compromise is therefore to accept a certain degree of cantdeflciencyforthevarioustrain. In this study, it was presented that effective maintenance method according to the investigation of cant value in radius of curvature and analysis safety running of train, calculation of lateral acceleration as cant deficiency, and we obtain the effect of speed up appling route alignment improvement parameter in curved lines zone.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.6
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• pp.53-60
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• 2011

The effect of exhaust heat recovery system can be evaluated by two well known method. First method is to measure the time duration from engine start under cold coolant temperature till coolant get warmed. By this methodology coolant warming duration can be index of warm-up effect. Second method is to analyze heat balance of the engine during warm-up phase under steady engine operation so that wasted energy by losses such as cooling and exhaust can be index of warm-up effect. This study focused on evaluation of warming-up effect by both methodology above mentioned using 2L SI engine under from idle to 2000rpm steady condition. Results, idle operation showed low heat recovery efficiency but under higher engine speed condition, remarkable heat recovery efficiency improvement was observed. In 2000rpm steady condition, warm-up duration of engine is decreased by exhaust heat recovery system.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.9
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• pp.813-821
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• 2000

In this paper, we developed modeling of tension and speed dynamics for a two-drum winder in a three span continuous web transport system which had not been previously. Dynamic modeling of the time-varying nonlinear system was derived by considering the effect of the radii and mass moment of inertia in the unwinder and the two-drum winder through winding up the web. After linearizing it, we designed with a variable-gain a PID controller for tension control and a PI controller for speed. Simulation is carried out with the variation of radii and moment of inertia at high speed for the proposed tension control system with the two-drum winder and the variavle-gain a PID controller. Results show good performance of tension control during the speed change speed at a start-up and stop.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.456-460
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• 2007

The original conventional railway was designed to be stand against 150km/h and it is still being operated at the present. However, if the speed of train is improved up to 200km/h in the near future in order to get competitiveness, we examined how the speed effect on the rail and we analyzed the effect of vibration, the stress and the displacement of the rail material by the change of the speed and the change of the property of matter through the hydrostatical and the dynamic analysis about the absence of the rail. As the result of the analysis by the above method, we got the prove that the best synthetic hardness of the rail is $75{\pm}10KN/mm$. Therefore, it is proved that rail pad has to be improved.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.382-385
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• 2001

The effect of agitation speed on the production of mycelial growth and exo-biopolymer in bioreaetor culture was investigated. The maximum production of mycelia and exo-biopolymer was obtained at 350 rpm, where the maximum concentrations of mycelial growth and exo-biopolymer were 62 g/L and 23 g/L, respectively. The effect of agitation speed on the hyphal length and the number of tips was examined. The hyphal length and the number of tips of Cordyceps sinensis 16 in bioreaetor culture at 350 rpm were increased up to 660 ${\mu}m$ and 14/ml, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.4
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• pp.65-72
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• 1990

After observing grinding characteristics according to variable grinding condition in order to raise the grinding effect without making worse the grinding quality by using general grinding machine, main conclusions of this study are as follows; 1) When grinding quality is constant, grinding effect is changed according to the speed of the workpiece. But the rapidly increasing critical speed of table is($V_w{\leq}4m/min$). 2) As grinding effect is equal, the lower the speed of the workpiece becomes, the lower the grinding force and surface roughness obtains good results. 3) In terms of grinding method, the down cut grinding method produces good grinding surface royghness in case of little grinding depth;otherwise, the up cut method in case of more grinding depth.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.278-281
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• 2008

This study demonstrates the advantages of a shear-free structure designed to modify vertical profiles of wind speed in the atmospheric surface layer. Computational fluid dynamics(CFD) software, FLUENT is used to interpret the velocity field modification around the structure and wind turbine. The shapes of shear-free structure, installed at upstream toward prevailing wind direction, would be fences, buildings and trees, etc. According to the simulation results, it is obvious that wind shear between heights of wind turbine's blades is decreased together with a speed-up advantage. This would lead decrease of periodic wind loading caused by wind shear and power-out increase by flow uniformity and wind speed-up.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.297-304
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• 2003

As the high speed rail to be opened at 2004, the. railroad will dominate over the transportation market in the Seoul-Busan corridor compared to road transport. But, it is obvious that the LOS(level of service) of railroad at 2004 will be worse in the areas that are not served KTX. For the speed-up of conventional line, it is a worldwide trend that tilting trains are served on the conventional railway line. That is the reason serving tilting trains is very efficient to use existing facilities and improve cruise time when capacity is available. In this paper, we suggest 10 routes are replaced with present operating trains(saemaeul, mugunghwa) by the tilting train.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1231-1237
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• 2000

Dynamics of a rotating cantilever beam near its critical angular speed is investigated in this paper. The external, force is idealized as a periodic function which has the same period as the rotati ng frequency of the beam. The equations of motion are derived and transformed into a dimensionless form. A prescribed spin-up motion is employed for the rotating motion. Numerical study shows that the steady state and the transient responses of the beam are affected by the spin-up time constant and there exists a time constant at which the maximum transient response becomes minimum.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.3
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• pp.62-67
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• 2003

The grinding force generated during the grinding process causes an elastic deformation of the workpiece, grinding wheel, and machine system. Thus, the true depth of cut is always smaller than the apparent depth of cut. This is known as machining elasticity phenomenon. The machining elasticity parameter is defined as a ratio between the true depth of cut and the apparent depth of cut. It is an important factor to understand the material removal mechanism of the grinding process. To increase productivity, the value of this machining elasticity parameter must be large. Therefore, it is essential to know the characteristics of this parameter. The objective of this research is to study the effect of the major grinding conditions, such as table speed, depth of cut, on this parameter experimentally, Through this research, it is found that this parameter value is increasing when the table speed is decreasing or the depth of cut is increasing. Also, this parameter value depends on the grinding mode (up grinding, down grinding).