• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.10
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• pp.1774-1779
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• 2016

This paper proposes a portable cable fault detection system with automatic fault distinction and distance measurement using time-frequency correlation and reference signal elimination method and automatic fault classification algorithm in order to have more accurate fault determination and location detection than conventional time domain refelectometry (TDR) system despite increased signal attenuation due to the long distance to cable fault location. The performance of the developed system method was validated via an experiment in the test field constructed for the standardized performance test of power cable fault location equipments. The performance evaluation showed that accuracy of the developed system is less than 1.34%. Also, an error of automatic fault type and location by detection of phase and peak value through elimination of the reference signal and normalization of correlation coefficient and automatic fault classification algorithm not occurred.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.11
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• pp.1820-1826
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• 2016

This paper deals with dynamic characteristics of the experimental magnetic levitation vehicle employing LSM(Linear Synchronous Motor) for propulsion. To predict the dynamic characteristics of the system, the dynamic model which is composed of the electrical elements such as electromagnets and LSM and mechanical components and is developed based on multibody dynamics is developed. The resulting system equations of motion for the model are a coupled one representing all the mechanical and electrical parts. To verify the dynamic model of the system, air gaps are measured in both running tests and simulation, and the frequency characteristics of air gaps are analyzed. From the results, it can be seen that the frequency responses are almost the same. Finally, to evaluate the levitation stability and the designed controller, numerical simulations are carried out.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.4
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• pp.242-249
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• 2016

The railway system is being converted to the computer system from the existing mechanical device, and the dependency on software is being increased rapidly. Though the size and degree of complexity of software for railway system are slower than the development speed of hardware, it is expected that the size will be grown bigger gradually and the degree of complexity will be increased also. Accordingly, the validation of reliability and safety of embedded software for railway system was started to become influential as the important issue. Accordingly, various software test and validation activities are highly recommended in the international standards related railway software. In this paper, we presented a software coding analysis tool using symbolic execution for railway system, and presented its result of implementation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.1
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• pp.7-12
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• 2016

With due to the recent development of USN (Ubiquitous Sensor Network) technology, a monitoring system has been developing for assuring the structural integrity of infrastructure through normal or long term measurements during their lifetime. An accident such as a collapse of infrastructure may cause not only loss of life but also damage to the economy of the nation. In order to enhance the availability of infrastructure and to be able to maintain their lifetime, it is necessary to monitor and to evaluate continuously the structural integrity throughout their entire lifetime. The purpose of this paper is to develop a monitoring system integrated with evaluation function based on the ubiquitous technology. The most essential part of this study is focusing more on developing a specific module convertible to A/D, which is to enhance the applicability of sensors that had not been applied to existing monitoring systems. Conclusively it has been successfully enhanced to make more diverse the number of sensors and measuring techniques for the monitoring system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.1
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• pp.108-111
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• 2016

We propose the method for measuring sensitivity of optical receiver of a long-range laser range finder in real-time. The sensitivity of the detector can be calculated using the detected voltage of the reference sensor, the area of the reference sensor and the transmittance ratio of neutral density filters. To evaluate the performance of the proposed method, we implemented a system and performed experiments. As a result, this system can be measured from 2nW to $113{\mu}W$. With this system, we measured the sensitivity of 37nW and 7nW with PIN PD and APD sample, respectively. This system has the advantage for the performance test of an optical sensor module in the long-range laser range finder.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.5
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• pp.59-64
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• 1998

In this study, a motor-integrated high-speed spindle system with $\psi$65mm $\times$ 25,000rpm is developed by introducing the oil-jet lubrication method, ceramic angular contact ball bearings, a built-in motor and so on. And oil-jet lubrication experiments fur evaluating the system performance are performed under various operation conditions. Especially, in order to establish the oillet lubrication conditions related to the development of a high-speed spindle system, the effects of oil supply rate and rotational spindle speed are investigated on the temperature rise, temperature distribution, motor current and so on.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.1095-1102
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• 2016

A TCS(Train Control System) is the core facility to ensure the safety and efficiency of train operations, it is difficult to have interoperability between the TCS suppliers. To ensure the interoperability between TCSs, there is a need for definition, validation and standardization on the system configuration, the functions of subsystems, the interface between subsystems an the system protocol. In this paper, we analyzed the completeness of the KRTCS(Korean Radio based Train Control System) specification, derived supplements what you need to apply the KRTCS specification to new urban lines.

• Journal of the Korean Operations Research and Management Science Society
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• v.17 no.1
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• pp.65-65
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• 1992

Recently many organizations have attempted to build hypermedia systems to expand their working areas to internet-based virtual work places. It is thus important to manage corporate hypermedia documents effectively. Metadata play a critical role for managing these documents. This paper identifies metadata roles and components to build its schema. Furthermore a meta-information system HyDoMiS(Hyperdocument Meta-information System) is proposed by the use of this metadata schema. HyDoMiS performs three functions metadata management search and reporting The metadata management function is concerned with workflow document and database. The system is more likely to help implement and maintsain hypermedia information system effectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.804-810
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• 2016

Photovoltaic system construction of the module capacity in domestic is specified criteria to less than 105% of the inverter capacity. However, the modules are installed in the outdoor actual output is reduced due to factors such as the irradiation intensity, module surface temperature. Thus, it needs the capacity of the inverter to be designed according to the actual module output. In this paper, the first approach to find the actual module output is to analyze the actual PV system monitoring data. Next, four sites where the loss analysis, system utilization, inverter utilization, and the ratio of the inverter overload are performed using PVSYST software. By changing the ratio of the module capacity, the inverter capacity of the site B is confirmed 20% less than the module capacity. Site A, C, D are identified as the ratio of the inverter capacity is 10% less than the module capacity.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.8
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• pp.1457-1465
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• 2016

A RCM approach to maintenance of the catenary system of electric railway is proposed. The proposed RCM approach provides a maintenance-oriented FMECA procedure to derive critical failure modes by analyzing failure effects and a RCM decision logic tree to suggest optimal maintenance works for the derived failure modes. By applying the proposed RCM procedures to the catenary system of high speed railway, it is suggested that strand breaks of dropper and voltage equalizing wire, and trolly wire wear-out are the critical failure modes for whom maintenance works based on condition monitoring should be applied instead of conventional time-based preventive maintenance. It is also proposed by reliability analysis that replacement time of dropper can be reduced from 18 years to 10 years. These results show that the proposed RCM approach can optimize the maintenance procedures of catenary system.