• KCID journal
• /
• v.2 no.2
• /
• pp.37-45
• /
• 1995

In this study, formulae related tidal current-stone diameter and weight have been analyzed based on the real sea dike construction situation. Three formulae which denoted Shields, Isbash and Netherlands's simple method have been compared by the various ti

• Research in Mathematical Education
• /
• v.1 no.1
• /
• pp.61-74
• /
• 1997

Currently, school computer education has turned to multimedia education, and the related policies are run by each regional authority of education. School principals and parents show strong interest on computer education and the movement into multimedia education as well. In current school education it also seems that computer use is being integrated into all subjects.

• Journal of Navigation and Port Research
• /
• v.41 no.2
• /
• pp.55-62
• /
• 2017

A nearshore current or a wave-induced current is an important phenomenon in a nearshore zone, which is composed of longshore, cross-shore, and rip currents. The nearshore current is closely related to the occurrence of coastal accidents by beachgoers. A considerable number of coastal accidents by beachgoers involving the rip current have been reported at Jungmun Beach. However, in studies and observations of the nearshore current of Jungmun Beach, understanding of the rip current pattern remains unclear. In this study, a scientific approach is taken to understand the nearshore current and the rip current patterns at Jungmun Beach by numerical computation for year of 2015. From results of numerical computation, the occurrence and spatial characteristics of the rip current, and the similarities between the rip current and incident wave conditions are analyzed. The primary results of this study reveal that the rip currents are frequently generated at Jungmun Beach, especially in the western parts of the beach, and that the rip currents often occur with a wave breaking height of around 0.5 ~ 0.7 m, a wave period of around 6 ~ 8 seconds, and a breaking angle of around 0 ~ 15 degrees.

• Journal of Power Electronics
• /
• v.11 no.1
• /
• pp.64-73
• /
• 2011

The stability of PWM rectifiers with a deadbeat current controller is seriously influenced by computation time delays and low-pass filters inserted into the current-sampling circuit. Predictive current control is often adopted to solve this problem. However, grid current predictive precision is affected by many factors such as grid voltage estimated errors, plant model mismatches, dead time and so on. In addition, the predictive current error aggravates the grid current distortion. To improve the grid current predictive precision, an improved deadbeat current controller with a repetitive-control-based observer to predict the grid current is proposed in this paper. The design principle of the proposed observer is given and its stability is discussed. The predictive performance of the observer is also analyzed in the frequency domain. It is shown that the grid predictive error can be decreased with the proposed method in the related bode diagrams. Experimental results show that the proposed method can minimize the current predictive error, improve the current loop robustness and reduce the grid current THD of PWM rectifiers.

• Proceedings of the KIEE Conference
• /
• 1997.07f
• /
• pp.2028-2032
• /
• 1997

When a high performance current control is desired, a computation time delay of a digital control system may deteriorate the control performance of a current controller. Such a non-negligible effect can be considerable in transient state. This paper deals with the modified predictive current control that compensates the time delay effects of a conventional predictive current control. The method is closely related to a local average current control and a symmetrical PWM pattern generation. Also some theoretical approaches are presented to describe the voltage saturation boundary of the power converter. For validation, the proposed method is applied to an active power filter system. The experimental results show considerable improvement in current tracking capability.

• Transactions of Materials Processing
• /
• v.13 no.3
• /
• pp.279-284
• /
• 2004

Electroforming is the highly specialized use of electrodeposition for the manufacture of metal parts and basically a specialized form of electroplating. So, we can apply electrochemical system analysis for electroforming process. Electrochemical systems are concerned with the interplay between electricity and chemistry, namely the measurements of electrical quantities, such as current density, potential, and charge, and their relationship to chemical parameters. This paper based on the basic equations of electrics and electrochemical kinetics, was employed for a theoretical explanation of the current density distribution on electroforming process. We calculated current density distribution and potential distribution on cathode. Also, calculated current density distribution of vertical direction. It was shown that current density is related with distance of between anode and cathode and mass transfer process.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.10 s.241
• /
• pp.1336-1343
• /
• 2005

The detection mechanism of the flaw for the nondestructive testing using eddy current is related to the interaction of the induced eddy currents in the test specimen with flaws and the coupling of these interaction effects with the moving test probe. In this study, the two-dimensional electromagnetic finite element analysis(FEM) fur the eddy current signals of the aluminum plate with different depth of surface cracks is described and the comparison is also made between experimental and predicted signals analyzed by FEM. In addition, the characteristics of attenuation of the eddy current density due to the variation of the depth of a conductor are evaluated. The effective parameters for the application of eddy current technique to evaluate surface cracks are discussed by analyzing the characteristics of the eddy current signals due to the variation of crack depths.

• Transactions on Electrical and Electronic Materials
• /
• v.3 no.1
• /
• pp.38-41
• /
• 2002

We have investigated current-voltage-luminance characteristics of organic light-emitting diodes based on TPD/Alq$_3$organics depending on the application of forward-backward bias voltage. Luminance-voltage characteristics and luminous efficiency were measured at the same time when the current-voltage characteristics were measured. We have observed that the current-voltage characteristics shows a reversible current maxima at low voltage, which is possibly not related to the emission from Alq$_3$. Current-voltage-luminance characteristics imply that the conduction luminance mechanism at low voltage is different from that of high voltage one.

• Journal of the Korean institute of surface engineering
• /
• v.27 no.5
• /
• pp.285-291
• /
• 1994

The effects of pulse current parameters on the composition and the microstructure of Pd-Ni alloy electrodeposits were studied. The cathode current efficiency of p.c. electrolysis conditions decreased with increasing both mean and peak current density and was lower than those under D.C. electrolysis condition. Palladium content of Pd-Ni alloy increased with increasing both peak current density and on-time, while it decreased with increasing mean current density and duty cycle. The preferred orientation of Pd-Ni alloys changed with increasing mean current density in the sequence of (111)+(110).(100) or (110)longrightarrow(111)longrightarrow(100) or random distribution of crystal structure. The surface morphology of Pd-Ni alloy changed mainly according to the mean current density and was related to the preferred orientation.

• Cartoon and Animation Studies
• /
• s.17
• /
• pp.69-81
• /
• 2009

Recently, the animation industry in China is rapidly developing drawing the government and the whole society's attention. To cope with a large-scale animation market by each region, they busily seek revitalization program of animation industry and are producing lots of animations that maximized their creative ability with its own competence and breaking the existing OEM production method. Up to now, when the scale of sales related with animation in China exceeds 10 times than that in Korea, the concrete studies on current state of animation education AS the basis of development of animation industry of China and the way of academic-industrial cooperation through that education are proved to be insufficient. Therefore, this study has surveyed and analyzed the current state of animation education by directly visiting 6 local universities related with animation. Equivocally, it has also examined current state of academic-industrial cooperation in industrial field related with animation in China by directly visiting around 10 main companies related with animation in China. Through this study, it has been possible to grasp the current state and problems of academic-industrial cooperation in China and various programs of academic-industrial cooperation system that can be implemented in universities and businesses which are intended to be suggested to them as based on this analysis. The touchstone of intensive studies on academic-industrial cooperation system in China could be suggested through this study, which has been previously unsatisfactory and it is considered to be worthy of application as many preceding studies that engraft on reality of education in the country today.