• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1659-1665
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• 2015

In general, AT(Auto-transformer) is used to improve voltage sag and inductive interference in power lines and communication lines in AC electrical railway feeding system. Especially, Korean AT feeding system has different composition compared to other countries like Japan or France, so that it has some special characteristics. However, relays imported from other countries have been used in Korea, and settings of these relays should be modified and reflect distinct characteristics of Korean AT feeding system. Therefore, study about fault analysis based on modeled AT feeding system is important. In this paper, we modeled a single track AT feeding system by using PSCAD and analyzed fault current flow in case of trolley-rail short circuit fault. Finally, we presented current magnitude of each branch expressed by boosting current of AT.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.344-351
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• 1999

The safe operation of electro railways is greatly dependant on its protective systems. The system so-called Fault Protection Wire(FW) is now widely adapted to protect in AT feeding systems. It is connected between the feeder and trolley circuit to return the fault current to autotransfonmers at substation. This paper computed the distribution of fault currents at FW in the system and also evaluated the safety from electric shock when ground fault or flashover occur in the feeding system. The results show FW is useful to protect power supply network from fault in electric railways

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1248-1250
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• 2002

AC AT feeding system is possible to do the long distance feeding due to compensate the voltage drop. Nowaday this is a typical and efficient type all over the world in high speed train and heavy transport capacity. Normally a Auto-transformer is installed at regular internal (5 to 10km) between Substation and Sectioning post, this study is reviewed the voltage drop according to train movement and the optimal location of auto transformer, and provided the efficient feeding configuration.

• Agribusiness and Information Management
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• v.4 no.2
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• pp.42-49
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• 2012

This study introduces cases of individual feeding systems for sow and the sow sorters which are the subparts of an eco-friendly feeding and management system based on a u-IT program using the hog feeding and management information system. The purpose of this study is to conduct an analysis of economic feasibility on cases of the improvement of the system using the u-IT and to provide information on the positive effects of an introduction of an eco-friendly pigsty and hog feeding and management system to hog raisers and government officials. The literature review and background section examine the effects of the introduction of u-IT technology into the field of livestock raising, hog feeding and management information system, and the eco-friendly feeding and management system based on the u-IT. This paper will present the results of the analysis on the effects and the economic feasibility of the individual feeding system for sow and the sow sorter utilizing the u-IT technology and information systems. The results of this study will contribute to the sustainable development of the hog raising industry by showing that the new feeding and management system utilizing the u-IT can not only increase the efficiency and productivity of farm management but also contribute to efficient, eco-friendly hog feeding and management.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1370-1376
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• 2015

Generally, an autotransformer(AT) feeding system consists of double tracks, up and down, with the trolley wire and feeder wire of the up and down tracks connected in the sectioning post(SP). Consequently, load current or fault current flows on two tracks based on catenary impedance characteristics, making it difficult to estimate catenary impedance accurately. This paper presents a technique for the estimation of catenary impedance using boosting current compensation based on the current division characteristics of an AT feeding system to improve the operation performance of impedance relay. To verify the technique, we model an AT feeding system through a power analysis program (PSCAD/EMTDC) and simulate various operation and fault conditions. Through the simulation, we confirmed that the proposed technique has estimated catenary impedance with a similar degree of accuracy to the actual catenary impedance

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.7
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• pp.1121-1127
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• 2016

In this paper, modeling of overcurrent relay(OCR) to protect domestic AC electric railway Auto Transformer(AT) feeding system and operation characteristic analysis on overload condition are described. The target system of this paper is actual site where overload trip of circuit breaker occurs frequently. Because this AT feeding system is made of parallel single track which had a load(electric train) respectively, and is connected with only T phase of Scott Transformer. In addition, this system has been feeding 66kV voltage by KEPCO, not 154kV. We focus on protective coordination of Scott Transformer primary side and secondary side OCR for Korea single track AC electrical railway system in operation currently. We modeled single track AT feeding system and OCR. Also we performed faults and overload analysis for verification of OCR's setting values and system modeling. To analyze above mentioned research, we used PSCAD/EMTDC software tool.

• Journal of Biosystems Engineering
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• v.26 no.3
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• pp.271-278
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• 2001

Many workers in the garlic peeling factory are separating the sound peeled garlics from the unpeeled and defective ones in a manual way. In order to reduce the seasonal labor requirement and operating cost, the mechanized garlic sorting system such as the vision-based garlic sorter should be developed. This study was conducted as one of basic studies on developing quality evaluation technique for peeled garlics, especially to developed the system for acquiring the whole surface images of garlics with a CCD camera. The following results were obtained from this study. 1. The belt-type garlic rotation system was devised to apply for the vision-based garlic sorter and was tested to decide the criteria of design and optimum conveying speed. 2. To evaluate the performance of the developed garlic rotation system, feeding rate and rotating rate were measured under the conditions of four experimental factors such as the inclined angle of rotating belt, the inclined angle of feeding belt, the height of plate arrays on feeding belt and the conveying speed of belts. And the capacity of the system according to mixture ratios of peeled garlics and unpeeled garlics was analyzed as a feasibility test. 3. For the inclined angle of rotating belt 20°and height of plate array on feeding belt 22㎜, the maximum rotating rate for garlic samples including unpeeled ones was 81.1% at the conveying speed of 4.2 garlic/sec. And under these condition, the maximum feeding rate was 85% at the inclined angle of feeding belt 6.5°. 4. The capacity of the developed garlic rotation system was almost constant regardless of mixture ratio of peeled garlics and unpeeled garlics and its range was 2.95∼3.92 garlic/sec. At the conveying speed of 4.2 garlic/sec, the capacity of the garlic rotation system was calculated ad 58∼64 kg/hr. 5. To improve performance of the garlic rotation system, it is recommended to develop a device to slide garlics into feeding belt.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.9
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• pp.1708-1714
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• 2011

AT feeding system of the electric railway system is installed every about 10km at between the feeder and catenary in parallel and the mid-point of the transformer is connected to the rail The supply voltage of this system is doubled than rolling stock voltage. So the voltage drop is smaller than usual. And the other merit of this system is the decreasing inductive disturbance to the communication line because of the reduced current in rail which runs reversed in a point of view of rolling stock. Also, ATP(Auto Transformer Post) is installed to reduce the voltage drop and to mitigate the inductive disturbance, but still now the proper distance between the ATP and AT feeding system is not established which ranges from 2 to 10[km]. The stable result of simulation(which is set that the end of the line AT is installed) to the voltage drop and inductive disturbance can not analyzes the effect to the supply system due to the ATP. This paper analyzes the effect to the system depending on the location of ATP by forecasting the voltage drop and inductive disturbance.

• Journal of Welding and Joining
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• v.31 no.3
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• pp.39-43
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• 2013

It is difficult to feed welding wire stably, when the distance between welding wire feeder and welding torch is far enough. In order to solve this problem, arranging a extension wire feeder between them could be one of useful methods. However, the welding wire could be twisted up in the extension cable between extension and terminal wire feeders in the case that RPM of extension wire feeding motor is higher than that of terminal motor. In this study, feeding problem of normal push-pull wire feeding system occurred at low welding current range less than 250A. In order to solve the problem, two new wire feeding systems of push-pull type were introduced. Welding wire feeding tests were preformed in the range of 150A to 400A with the developed push-pull feeding system. In addition, weldability test was performed at the welding current of 200A, 300A, and 400A. The welding wire twisting problem that was observed in the normal feeding system did not occur in the new push-pull wire feeding system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.79-82
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• 2004

Propellant feeding system is the system to satisfy propellant feeding requirements(mass flow rate, pressure, temperature) at engine inlet of launch vehicle. Propellant feeding test facility is being constructed for the development scheme of pressurization system, processing in tank, propellant piping system, and flow control system that are main technologies in order to develope propellant feeding system. This paper introduces the propellant feeding test facility being constructed in KARI.