• Journal of Korean Society for Quality Management
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• v.34 no.4
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• pp.125-132
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• 2006

An adjusted control limit of the $\overline{X}$ chart is proposed for monitoring the continually improving processes. The continual improvement of the process implies the decrease of the process variance, which is represented by a logistic curve. The process standard deviation is estimated by the exponentially weighted moving average of the sample standard deviations from the past to the current times. The control limits are adjusted by the estimated standard deviation at every sampling time. The performance of the adjusted control limit is compared with that of the standard control limits for various cases of the decreasing speed and size of the variance. The results show that the $\overline{X}$ chart with the adjusted control limits provides better performances for monitoring the small and moderate shifts in continually improving processes.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.278-282
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• 2003

This paper presents TPS(Train Performance Simulation) which identified the condition of train operationing in short time. Using the program, the location of train, maximum current, metering power and regenerating of train, could be identified. This is an important part for Power Simulation. It is supposed that the grade, the curve, the limit speed and the current speed be constant within the time step in the conventional papers. In addition, the errors of the grade and the curve in each station interval are neglected. This paper will introduce improvement method the problem of TPS.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.778_779
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• 2009

The maximum output torque developed by the machine is dependent on the allowable current rating and maximum voltage that the inverter can supply to the machine. Therefore, to use the inverter capacity fully, it is desirable to use the control scheme considering the voltage and current limit condition, which can yield the maximum torque per ampere over the entire speed range. The paper is proposed maximum torque control of induction motor drive using adaptive learning neuro fuzzy controller and artificial neural network(ANN). The control method is applicable over the entire speed range and considered the limits of the inverter's current and voltage rated value. For each control mode, a condition that determines the optimal d, q axis current $_i_{ds}$, $i_{qs}$ for maximum torque operation is derived. The proposed control algorithm is applied to induction motor drive system controlled adaptive learning neuro fuzzy controller and ANN controller, the operating characteristics controlled by maximum torque control are examined in detail. Also, this paper is proposed the analysis results to verify the effectiveness of the adaptive learning neuro fuzzy controller and ANN controller.

• Journal of the Korean Society for Railway
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• v.11 no.5
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• pp.489-498
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• 2008

In general, deflection limit criteria of bridge design specifications have been considered based on static serviceability and structural stability. Dynamic serviceability induced from bridge vibration actually has not been included in the criteria. Thus, it is necessary for deflection limit to be considered in order to check dynamic service- ability on bridge vibration. In this study, The allowable displacement of Korea Railway Bridge Design Specifications is compared to the frequency domain comfort limit and analyzed france code and japanese code. Korea Railway Bridge Design Specifications is regulated based on the train speed. Such is because the vibration time duration is partly considered. but this criteria is not satisfied with comfort limit. and, it is estimated to be capable to provide deflection limit considering dynamic serviceability. In order to evaluate the dynamic serviceability of various types of railway bridges in current public were selected and their dynamic signals were measured. and the result of the bridge-train interaction analysis according to the changes in bridge stiffness was compared to the comfort limit to suggest the stiff-ness limit to the dynamic serviceability, which should conveniently be applied at the field.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.832-837
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• 2006

ATC facility manipulates ground-on-board information, which transmits speed limit, varying as wayside environments - safety facility, track gradient, inclination, bridge and tunnel and other factors, installed for safe operation of trains on wayside. Efficientiation and automatification of operation and maintenance is being realized, by measuring if there are any erroneous information, using a measuring car. In this paper, we study in priority the methods for measuring accurately distinctive properties of internal malfunctions of track circuits, the performance decrease of condensers, and the unbalance of return cables, which are actually required for functionality improvement of high-speed line signal measure facilities, by measuring the unbalance of return current given because of damaged factors of external track circuits.

• Journal of Magnetics
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• v.16 no.1
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• pp.71-73
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• 2011

Hybrid electric vehicles have attracted much attention of late, emphasizing the necessity of developing traction motors with a high input current and a wide speed range. Among such traction motors, various researches have been conducted on interior permanent-magnet synchronous motors (IPMSMs) with high power density and mechanical solidity. Due to the complexity of its parameters, however, with nonlinear motor characteristics and current vector control, it is actually difficult to accurately estimate the base speed within an actual operating speed range or a voltage limit. Moreover, it is impossible to construct an efficiency map as the efficiency differs according to the control mode. In this study, a simulation method for operation performance considering the nonlinearity of IPMSM was proposed. For this, datasets of various nonlinear parameters were made via the finite-element method and interpolation. Maximum torque-per-ampere and flux-weakening control were accurately simulated using the datasets, and an IPMSM efficiency map was accurately constructed based on the simulation. Lastly, the validity of the simulation was verified through tests.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.5
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• pp.86-95
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• 2003

It had been strictly prohibited to plant in waterway according to Korea laws and regulations. It was then made possible to plant by the modification law and regulation of 10/30/1997. In 2000, the Seoul metropolis government planted in the Yeoyido flood plain park in Han river by way of showing the model case. This planting design is for the Yeoyido flood plain park along the Han river, in Seoul. The design requirements were to create a pleasant rest area, to improve the surrounding landscape, and to create diverse ecological habitats by planting within the stability of flood flow. This design emphasizes the following design requirements that has positive effect on stabilizing flood flow. First, planting suitable in a area was determined by the speed of a current of less than 0.7m/sec under various numerical value simulations. Second, plants were selected in existing trees of the present and the past Han river, as well as the questionnaire results from landscape professional engineers and professors. Shade plants were planted in the large visiting areas so as to offer pleasant shade in the summer, the ecological planting pattern was applied in the area with low speed of flood flow, so as to aid the restoration of the natural ecological environment. It was found that the foresaid planting design verified the stability of flood flow and wind by overturn limit moment calculation. It is expected that this plan would serve environmentally friendly planting plans in flood plain park.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1045-1047
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• 2003

The development of linear Eddy-Current brake systems has gradually gone beyond the adhesion limit in high-speed vehicles. In particular, the practicality of using permanent magnet in Eddy-Current brake systems is obviously recent, due to the manifold improvement in magnet materials and technology. On the basis of analytical two-dimensional field solution, this paper deals with flux density and force calculation about the linear Eddy-Current brake systems: DC excited electromagnet, Halbach magnetized and vertical magnetized permanent magnet.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1069-1070
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• 2008

At the coupling area linking high speed line and conventional line, according to distance between trains due to speed limit of conventional line, the power load of substation supplying to this conventional line increase. At the coupling area between Kimcheon SS and Kyoungsan SS, train operation have problems caused by instantaneous voltage drop. So, this paper propose evaluation method of maximum load capacity at current normal feeding condition.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.33 no.8
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• pp.316-324
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• 1984

In the wound rotor induction motor, the external resistor is usually added to the rotor circuit in order to limit the starting current. In this scheme, whilst the starting current is limited, the available torque is remarkably reduced. In this paper, to improve the starting characteristics the stator current can be maintained constant by adjusting the external resistor. To change the external resistor, teh chopper and the resistor is connected in parallel, and the chopper duty cycle is adjusted by microprocessor. The duty cycle is calculated according to the actual speed of motor by microprocessor look-up table map. In this suggested scheme, the starting characteristics are remarkably improved without over-current. The starting time of this system is reduced by 20-48 Percent compared with fixed extemal resistance system in the same load.