• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1210-1214
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• 2008

Electro-pneumatic servo valve is an electro-mechanical device which converts electric signal into pneumatic flow rate or pressure. In order to improve the overall performance of pneumatic servo systems, electro-pneumatic servo valves are required, which have fast dynamic characteristic, no air leakage at null, and can be fabricated at a low-cost. The first objective of this research is to design and fabricate a new electro-pneumatic servo valve which satisfies the above-mentioned requirements. In this paper, we has been modeled as a system consisting of coupled electro-mechanic and mechanical subsystems. The appropriateness of the model has been verified by simulation. The simulation model resolves the valve body motion and the solenoid current at high accuracy. Also, we are calculate the displacement of spool and computed results show winding currents, magnetic actuator force, flux density line, displacement, velocity, back EMF, eddy current etc.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.589-590
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• 2006

Recently, research for the micro printing technology has begun to get into the spotlight. It is due to the superior price competitiveness to existent semi-conductor process for manufacturing some parts of display unit, electronic paper, RF-ID information device, and so on. This paper present screen printing process not for paper publication but for parts of electronics such as PDP wall, LCD CF, and so on. There are two major issues. The first one is how to get a fine and even line pattern. The other one is how to get the same patterns in large area. In this research, we present the design, equipment, and process control of screen printing in order to overcome these issues.

• 전기의세계
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• v.20 no.4
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• pp.31-36
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• 1971

This is intending to introducdine the pipe type 161KV underground cable system in Capital City of Seoul which will be constructed in 1972 or 1973 by Korea Electric Co using the AID loan and Won currency. In order to make readers to have an easy understanding and a clear view of underground cable transmission line, the first part will be for the introduction of the description on future underground cable system by Mr. E.H.F inch appeared on 1969 Sept. Consulatant Engineer. the second part will introduce our 161KV underground cable system in Seoul and it's feasibility study, and the third part will mention calculation methods of electrical properties of pipe type cable and the results of calculation of our own system.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.1
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• pp.15-22
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• 2001

In this paper, a VSC(Voltage Sag Corrector) is discussed for the purpose of power quality enhancement. A fast detecting technique of voltage sag is accomplished through the detection of instantaneous value on synchronous reference frame. A robust characteristic against the noise is available by inserting the first order low pass filter in the detection circuit. The formula and the filter design process is described properly with the mathematical equations. Because the VSC system supply the active power to load, it is required to design the proper size of the energy storage system, In this paper, the capacitor bank is used as an energy storage system, and the size of the capacitor is designed from the point of view of input/output energy as the output power rating and the amplitude and duration time of the voltage sag. The simulation is accomplished by PSCAD/EMTDC.

• Journal of Information Processing Systems
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• v.15 no.6
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• pp.1392-1405
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• 2019

The cathode voltage of aluminum electrolytic cell is relatively stable under normal conditions and fluctuates greatly when it has an anomaly. In order to detect the abnormal range of cathode voltage, an anomaly detection algorithm based on sliding window was proposed. The algorithm combines the time series segmentation linear representation method and the k-nearest neighbor local anomaly detection algorithm, which is more efficient than the direct detection of the original sequence. The algorithm first segments the cathode voltage time series, then calculates the length, the slope, and the mean of each line segment pattern, and maps them into a set of spatial objects. And then the local anomaly detection algorithm is used to detect abnormal patterns according to the local anomaly factor and the pattern length. The experimental results showed that the algorithm can effectively detect the abnormal range of cathode voltage.

• Kyungpook Mathematical Journal
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• v.60 no.3
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• pp.629-645
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• 2020

A uniformly convergent numerical method is developed for solving singularly perturbed 1-D parabolic convection-diffusion problems. The developed method applies a non-standard finite difference method for the spatial derivative discretization and uses the implicit Runge-Kutta method for the semi-discrete scheme. The convergence of the method is analyzed, and it is shown to be first order convergent. To validate the applicability of the proposed method two model examples are considered and solved for different perturbation parameters and mesh sizes. The numerical and experimental results agree well with the theoretical findings.

• Journal of the Korean Institute of Navigation
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• v.10 no.2
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• pp.57-81
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• 1986

The conventional school affairs management, with an example of Korea Martitime University (KMU), is studied through the university codes and its internal regulations and the inevitable problems of the conventional school affairs are analyzed. From the view points of complexity of the educational structure and increase in educational population, the computerized school affairs management is increasingly requested. Therefore, in order to design and implement a computerized school affairs management system, a code-system suitable for the KMU is, first of all, constructed and then a data base which copes with various reforms or changes is developed by using the code system and the IMAGE/DMBS of a HP-9040AM computer. A FORTRAN example program shows that the designed data base can be easily transformed into on-line system and made good use of managing school affairs. Furthermore, it is recommended that the university authority organize a research team for designing the total system in future university administration and solving difficult problems occurring through the computerization.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1405-1407
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• 2000

This paper is on optimal design for DC substation capacity for Mass Transit System. Three factors are considered for the design i.e. substation arrangements, line configuration and substation power capacity. In this study, we discussed substation power capacity only. At first, DC-fed-traction system is introduced on an outline, a characteristics of train and fed network. Optimal design procedures is described, and modelling for DC-fed-traction system are presented. The circuit-solution method is presented by matrix formula. In order to simulate DC substation power capacity more closely to actual situations, we proposed the program.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.152-157
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• 2005

Recently, higher speeds have been promoted in old overhead-lines. For high-speed operation in electric railways, increasing contact loss of the pantograph is one of the most important subjects. The contact loss causes power interruption and increases wear of contact strips and contact wires. In order to investigate the causes of contact loss and to work out effective improvement methods, theoretical analyses, experiments have been carried out. First of all, the wave propagating velocity (phase velocity) and characteristics of contact wire are one of the important indices for the current collecting performance. In this paper, mathematical formula arc derived for the prediction of the traveling wave velocity. The measured values in the experiment agree well with the theoretical predictions.

• Journal of the Ergonomics Society of Korea
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• v.9 no.1
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• pp.21-27
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• 1990

Teaching Expert System/World Coordinate System(TES/WDS) was proposed to improve robot motion control. First, precise coordinate reading for getting the inherent data about position and posture of task objects was performed throgh the integrated image and fuzzy processing. Second, singularity and parameter limitation problems in getting the motion data about position and posture of robot in macro motion were solved by proposed geometric algorithm. Third, the unnecessary robot motion was also removed by the Robot Time and Motion (RTM) method and the Multi-Geometric Straight-Line Motion (MGSLM) method in micro motion. This results demonstrated reduction of the average teaching task time according to task order.