• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.3
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• pp.83-90
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• 2001

This paper resents an algorithm for the optimal parameter selection of a power system stabilizer in a single machine-infinite bus system through the external equivalent transmission line. This method is one of the classical techniques by changing the PSS gain to allocate properly pole-zero positions. All the PSS parameters are obtained by solving a set of algebraic equations for the system constants depend on a variety of machine loadings and system external impedances, the natural oscillation modes, and the damping characteristics. And this algorithm was written in a simple software program using MATLAB.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.4
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• pp.700-704
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• 2011

This paper proposes a coordinative protection study results of 22.9kV HTS(High-Temperature Superconducting) cable implemented distribution system. HTS cable can provide about 5 times larger transfer capacability compare to conventional XLPE cable, however, it has different heat characteristic so called quench. This paper presents the simulation results on Ichun substation HTS cable which connects main transformer and 22.9kV bus. Various expected fault cases are considered and discussed to examine whether conventional protection scheme is effective to protect both of existing facilities and HTS cable. With the results of simulation, conventional protection scheme can be used if instantaneous element and time inverse elements could be adjusted with proper time coordination. Internal temperatures of HTS cable conductor in safe region with proper protection without quench. This results are to be demonstrated by the field test and will be implemented in Ichon substation HTS cable protection and control system.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.519-523
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• 2003

This paper describes the communication system of sequencing sorter. Generally sequencing sorter is a machine that sorts mails by delivery order. And designed sequencing sorter is composed of 5 physical modules. So, it is necessary to communicate with each module and to control this communication. A computer called Machine Management Computer, controls this. This paper is about the communication system with MMC and module controllers. This is PC-based, asynchronous full-duplex 4-wire serial systems. 3 protocol layers are presented and stop-and-wait flow control is adopted. Because designed sequencing sorter has to be operated high speed about 27,000 letters per hour, we analyzed the network traffic in the worst case. So, we could find that the communication system has to use above 115,200bps speed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.942-945
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• 2005

This paper tried to analyze the collection and management method of shop-floor information for development of digital framework in u-manufacturing. In detail, the shop-floor information collection method through the direct communication with manufacturing devices using network Including RS-232C/422, field bus and ethernet is analyzed and proposed. In case the direct communication is impossible, the information collection method through additional sensors or data acquisition units is analyzed and proposed. Moreover, the collection method through bar code reader or touch screen of operators is analyzed and proposed to act up to machine to man/mobile/machine.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.11a
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• pp.143-148
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• 1999

A distributed real-time system that is being wed now is usually divided into three level : higher level, middle level, and lower level. The higher level network is usually called an information network, the middle level is called a control network, and the lower level is called a field network or a divice network. This dissertation suggests and implements a middle level network which is called PICNET-NP (Plant Implementation and Control Network for Nuclear Power Plant). PICNET-NP is based partly on IEEE 802.4 token-passing bus access method and partly on IEEE 802.3 physical layer. For this purpose a new interface, a physical layer service translator, is introduced. A control network using this method is implemented and applied to a distributed real-time system.

• Journal of Auto-vehicle Safety Association
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• v.13 no.2
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• pp.42-49
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• 2021

In this paper, we proposes a study on the derivation of inspection factors for the periodic inspection of large buses equipped with AEBS and LDWS. we investigate the safety evaluation (NCAP) of domestic and foreign vehicles and safety standards for the two functions currently in operation and analyze the evaluation factors, measurement methods and evaluation scenarios and so on. In addition, the test scenario was derived by analyzing the vehicle safety evaluation data already held, Therefore, we use an real large bus and the inspection elements for the periodic inspection were derived.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.370-375
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• 2008

When customer makes a phone call to get the necessary information, ARS (Automatic Response System) will provide them without the limitation of time and place. Therefore, the application field of ARS (Automatic Response System) has been expanded and also occupancy rates arepretty high. However, compared with the importance of ARS, there is little study regarding the closest information structure of the actual users. Therefore, this research is about the ARS information structure of Gimhea BIS (Bus Information System), and the point of this research is to analyze the problem of the ARS information structure so we can suggest an idea to improve it. As the methods of study, drawing the workflow of ARS, conducting user observation, comparing with cases another region and analysis them. As a result, by and large there was error in the structure of information so, system reformation was required. Now that, we suggested two ideas for the improvement and we conducted usability test under that problem. Usability test was conducted by Lab test with interview. As a result, we could understand merits and demerits of two ideas for improvement, and we completed final improvement to highlight only merits of two ideas for improvement. This study will be utilized as the base material to improve ARS of Gimhea BIS.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.6
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• pp.677-685
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• 2011

In order to enhance public transportation and to maintain information credibility, improvement of accuracy regarding route and positional information of public transport is very significant. There have been a variety of methods using GPS to measure accuracy of location-based services. However, the researches of evaluation regarding kinematic position of linear objects measured by vehicle/kinematic GPS are still insufficient. That's why our paper aims to suggest method of evaluation accuracy on a real-time bus route surveyed by GPS by SBM(Single Buffering Method). To make it come true, we compared the findings on the static and dynamic positioning by using PP(Point Positioning), DGPS and GPS/INS integrated systems and analyzed the accuracy and error effects among them, focusing on Anyang city. Consequently, we can find out that in case of P.P. comparing positioning accuracy between RTK DGPS and GPS/INS, both of them have survey result within a margin of error of 5m. More importantly, we can evaluate positional accuracy of each GPS system based on the work provision of a public survey such as error for P.P.(14.5m, 18.1m), DGPS(16.9m, 18.5m), and GPS/INS(18.4m, 18.5m). We are expecting that proposed method in our paper can be utilized in a wide range of categories such as feasibility testing of GPS field survey and high accuracy of positioning for Bus Information System.

• Journal of vocational education research
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• v.35 no.6
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• pp.21-38
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• 2016

The purpose of this study is to analyze an experience of field practice perceived by vocational teachers. Data for analysis were collected from 689 vocational teachers who participated in the training at the Center for in-service teacher education in the School of Agriculture and Life Sciences, Seoul National University and at the Center for in-service teacher education of Chungnam National University. After screening, 685 responses were used in the analysis. As a result, it turned out that only 112 vocational teachers(16.5%) participated in the field practice for more than 4 weeks when they were in pre-service education. However, vocational teachers seemed to perceive that experience of field practice was generally required in pre-service education(average 4.07). In-depth questionnaire was conducted on 143 respondents who replied that they participated in field practice program for more than 4 weeks and those who participated in the program for less than 4 weeks but completed the paperwork. Most of vocational teachers who participated in field practice were placed in small and medium sized enterprises, stayed at home or relatives' home and commuted by the bus or subway. In this research, 34.8% of the vocational teachers who participated in field practice received financial compensation and 80.3% of the teachers got credit recognition. The perception of satisfaction on field practice program was found to be moderate(average 3.51).

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.653-658
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• 2023

In systems like the combat management system of a naval ship or smart city of civilians, where many sensors and actuators are connected, the middle-ware DDS (Data Distribution Service) is mainly used to transmit large amounts of data. It is scalable and can effectively respond to the increase in sensors or equipment connected to the system in the future. The engineering control system (ECS), which plays an important role similar to the combat management system of a naval ship, still uses Server-Client model with industrial protocols such as Modbus and CAN (Controller Area Network) bus, to transmit data, which is unfavorable in terms of scalability. However, as automation and unmanned systems advance, more sensors and actuators are expected to be added, necessitating substantial program modification. DDS can effectively address such situations. The purpose of this study is to confirm the development possibility of an integrated monitoring and control system of a ship by using OpenDDS, which follows the OMG (Object Management Group) standard among the middle-ware DDS used in the combat management system. To achieve this goal, field equipment simulators and an ECS server were configured to perform field equipment data input/output and simulation using DDS was performed. The ECS prototype successfully handled data transmission, confirming that DDS is capable of serving as the middle-ware for the ECS of a ship.