• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1191-1192
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• 2011

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.2
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• pp.55-60
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• 2014

In general, A synchronous generator is higher than the voltage stability of the induction generator. However, induction generator has many advantages rather than a synchronous generator in terms of price and maintenance. So, coverage rate of the induction generator is gradually increasing in small hydroelectric power station rather than 1000kW recently. In order to increase the penetration of induction generator, pre-analysis of the operation of the generator is needed. In this study, we analyzed for the problems that occur when synchronous generator and induction generator of 1500kW is connected to the distribution system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1226-1231
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• 2012

The demand for electrical power has been significantly increased to satisfy the customers. As a result, a power distribution system have been advanced by power system's interconnection, installation of distributed generator(DG) and so on. The improvable power distribution system included the problem of increasable fault current. Superconducting fault current limiter (SFCL) is one of the solutions to limit a fault current. Therefore, to solve the problem of fault current by SFCL, simulation was progressed and the simulation used a PSCAD/EMTDC.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.129-132
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• 2008

Combustion characteristics of a gas generator for a 30 ton-class liquid rocket engine were studied. At the early stage of development, the combustion tests of the gas generator were performed by only using the nozzle which substitute for a turbine manifold exit. Then, the extension tube was applied between the gas generator and the nozzle for imitating the resonant mode of gas generator and turbine manifold. Finally, the hot-firing tests were performed on the condition of connecting the gas generator with the turbine manifold. In the paper, the step-by-step results such as temperature distribution and pressure fluctuations were analyzed.

• Biomedical Engineering Letters
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• v.8 no.4
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• pp.383-392
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• 2018

For prompt gamma ray imaging for biomedical applications and environmental radiation monitoring, we propose herein a multiple-scattering Compton camera (MSCC). MSCC consists of three or more semiconductor layers with good energy resolution, and has potential for simultaneous detection and differentiation of multiple radio-isotopes based on the measured energies, as well as three-dimensional (3D) imaging of the radio-isotope distribution. In this study, we developed an analytic simulator and a 3D image generator for a MSCC, including the physical models of the radiation source emission and detection processes that can be utilized for geometry and performance prediction prior to the construction of a real system. The analytic simulator for a MSCC records coincidence detections of successive interactions in multiple detector layers. In the successive interaction processes, the emission direction of the incident gamma ray, the scattering angle, and the changed traveling path after the Compton scattering interaction in each detector, were determined by a conical surface uniform random number generator (RNG), and by a Klein-Nishina RNG. The 3D image generator has two functions: the recovery of the initial source energy spectrum and the 3D spatial distribution of the source. We evaluated the analytic simulator and image generator with two different energetic point radiation sources (Cs-137 and Co-60) and with an MSCC comprising three detector layers. The recovered initial energies of the incident radiations were well differentiated from the generated MSCC events. Correspondingly, we could obtain a multi-tracer image that combined the two differentiated images. The developed analytic simulator in this study emulated the randomness of the detection process of a multiple-scattering Compton camera, including the inherent degradation factors of the detectors, such as the limited spatial and energy resolutions. The Doppler-broadening effect owing to the momentum distribution of electrons in Compton scattering was not considered in the detection process because most interested isotopes for biomedical and environmental applications have high energies that are less sensitive to Doppler broadening. The analytic simulator and image generator for MSCC can be utilized to determine the optimal geometrical parameters, such as the distances between detectors and detector size, thus affecting the imaging performance of the Compton camera prior to the development of a real system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.3
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• pp.151-157
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• 2003

Wind farm interconnected with grid can supply the power into a power network not only the normal conditions, but also the fault conditions of distribution network. If the fault happened in the distribution power line with wind fm, the fault current level measured in a relaying point might be lower than that of distribution network without wind turbine generator due to the contribution of wind farm. Consequently, it may be difficult to detect the fault happened in the distribution network connected with wind generator This paper describes the effect of the interconnected wind turbine generators on protective relaying of distribution power lines and detection of the fault occurred in a power line network. Simulation results shows that the current level of fault happened in the power line with wind farm depends on the fault impedance, the fault location. the output of wind farm. and the load condition of distribution network.

• Journal of Energy Engineering
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• v.8 no.1
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• pp.76-84
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• 1999

The demand of Small Self-generating System (SSS) including Small Cogeneration System (SCS) is constantly increasing with the need of electricity and/or thermal in office, hospital, hotel, and small factory, etc. It is especially recommended to operate SCS in the heat-following mode to maximize the efficiency of generator. In case of the heat-following mode SCS has got to be connected to distribution system so as to send surplus power to the utility or receive the short power from utility. But the interconnection of SSS with distribution system causes a few problems such as the bad power quality, and low security. If SSS is not promptly disconnected after faults occur (Islanding of SSS), it can not only damage equipment of utility and adjacent customers but also endanger life of human due to overvoltage or overcurrent. In this paper it has been deeply discussed if interconnection of engine self-generator/control system satisfies the protective requirement for SSS or not. 500 kW engine generator running in the Jodo island has been used to perform the analysis of interconnection.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.216-220
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• 2000

AC Superconducting Generators (ACSG) are featured by 3D magnetic flux distribution, which decreases in the direction of axis. For this reason, when ACSG is optimal designed, 3D magnetic field analysis is required. This paper proposes 2D Finite Element Analysis (FEA) results normalized by 3D FEA according to the position of armature coil and the ratio of field coil width to axial length in order to reduce the analysis time. By using the proposed data, the reasonable 3D FEA results of ACSG can be only predicted by 2D FEA results. The validity of the 3D FEA results is verified by comparison with the experimental results of 30kVA superconducting synchronous generator.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.1965-1970
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• 2016

This paper studies generator rescheduling technique for congestion management in power system with wind farms. The proposed technique is formulated to minimize the rescheduling cost of conventional and wind generators to alleviate congestion subject to operational line overloading. The generator rescheduling method has been used with incorporation of wind farms in the power system. The locations of wind farms are selected based upon power transfer distribution factor (PTDF). Because all generators in the system do not need to participate in congestion management, the rescheduling has been done by generator selection based on the proposed generator sensitivity factor (GSF). The selected generators have been rescheduled using linear programming(LP) optimization techniques to alleviate transmission congestion. The effectiveness of the proposed methodology has been analyzed on IEEE 14-bus systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.4
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• pp.1307-1329
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• 2022

This paper proposes an improved Pseudorandom Sequence Generator (PRSG) based on the concept of modular arithmetic systems with non-integral numbers. The generated random sequence use in various cryptographic applications due to its unpredictability. Here the mathematical model is designed to solve the problem of the non-uniform distribution of the sequences. In addition, PRSG has passed the standard statistical and empirical tests, which shows that the proposed generator has good statistical characteristics. Finally, image encryption has been performed based on the sort-index method and diffusion processing to obtain the encrypted image. After a thorough evaluation of encryption performance, there has been no direct association between the original and encrypted images. The results show that the proposed PRSG has good statistical characteristics and security performance in cryptographic applications.