• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.622-626
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• 2002

Combined generation system of photovoltaic and wind power is required backup system that such as a storage battery to supply energy, when not enough photovoltaic and wind power source for power supply equally and continually, because the energy source is changeable and stable through change of weather as irradiation, temperature, wind speed, wind speed, wind direction, seasons, etc..

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.121-124
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• 1990

Distance relaying is one of the most commonly used protection schemes in the high voltage transmission systems. In this scheme, coordination between the primary and backup relays is very critical for the power system security. This paper reports an rule-based methodology for checking and correction of miscoordination problems in the distance relaying. Diagnosis rules achieving an accurate but simple checking have been developed through the geometric analysis of the impedance characteristics of the distance relays. Heuristic rules having the pratical power for miscoordination correction are suggested. The proposed method has proved very effective through the several case studies on the actual systems.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.2
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• pp.33-39
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• 2013

Multilateration(MLAT) may complement secondary surveillance radar and also act as a real-time backup for the ADS-B system. This System is using time difference of arrival (TDOA) and based on triangulation principle. Each TDOA measurement defines a hyperbola describing possible aircraft locations. The accuracy in MLAT system depends on the positional relationship of the receiver and aircraft. There are various algorithms to localize aircraft based on TOA estimation. In this paper, we use least square method and extended Kalman filter and compare their results. Study results show that the extend Kalman filter provides a better performance than the least square method.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1106-1110
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• 1998

Voltage Sags, different from electric outages, are important to industrial reliability because modern process controls are often sensitive to voltage sag, the designer and operator should recognize sag characteristics of the electric system not only to protect malfunction of equipment but also to make best choices between reliability and equipment cost. The voltage sags and compensation countermeasures of large md industrial distribution systems have been simulated using EMTDC. The causes of voltage sags occurred in the system are discussed in detail and several countermeasures including the transfer of large induction motor from normal power source to backup source are recommended in order to enhance the ride-through characteristics of equipments.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1698-1699
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• 2007

This paper deals with the surge measurement system for low voltage power line of industrial plants. It consists of a capacitive divider, A/D conversion part, signal processing and control part. A FPGA and a DSP board were designed to fast signal processing and control. Also, in order to measure lightning surge and switching surge for a long time, data backup device was applied by using SD memory. A performance of the measurement system was verified through evaluation test using impulse calibration generator.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.6
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• pp.491-496
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• 2005

In this paper, test on characteristics of 3-phase line-interactive UPS system, known as delta conversion UPS system, is studied. Delta conversion UPS system is new line-interactive UPS system using two series-parallel PWM converters instead of using series inductor in conventional single conversion line-interactive UPS system. It is known that the characteristics of input and output in delta conversion UPS system is much improved by controlling source current of AC lines directly. Here the results on load test, normal/backup mode test, and normal/bypass mode test, which are very important in the test on characteristics of UPS system, is presented. And finally overall evaluation on delta conversion UPS system is given.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.5
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• pp.554-561
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• 2014

Hybrid wind Diesel stand-alone power systems are considered economically viable and effective to create balance between production and load demand in remote areas where the wind speed is considerable for electric generation, and also, electric energy is not easily available from the grid. In Wind diesel hybrid system, the wind energy system is the main constitute and diesel system forms the back up. This type of hybrid power system saves fuel cost, improves power capacity to meet the increasing demand and maintains the continuity of supply in the system. Problem we face in this system is that even after producing enough power through wind turbine system, considerable portion of this power needs to be dumped due to short term oversupply of power and to maintain the frequency within close tolerances. As a result remaining portion of total energy supplied comes from the diesel generator to overcome the temporal energy shortage. This scenario decreases the overall efficiency of hybrid power system. In this study, efficient Simulink modeling for wind-diesel hybrid system is proposed and some simulations study is carried out to verify the feasibility of the proposed scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.10
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• pp.2323-2330
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• 2014

Most organizations are more depending on information system in advanced information society. According to this current, unrapid reaction to system failure can cause a fatal effect to a credibility of the organization. An excessively high level of dependence on information system at work makes itself as a primary target of cyber terror. The stability of university's information system is especially weaker than the enterprise's but policy support for securing availability is inadequate. In this paper, we consider the recovery system toward to disorder of university's school affairs information system theoretically and suggest high availability PC based academic administration system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.6
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• pp.23-30
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• 2003

This paper analyzes the characteristic of utility connection type solar power generation system which it is available to connect the utility. And the operation characteristic of this system is compared and analyzed when it is operated in the real system. The constructional and operational problem were obtained by that result. Overcoming that defect is that finding the proper place to be well operated and to find the best place for getting the sunshine data. This method could increase the efficiency of the generation system. And more, current OS in operating system and monitoring management couldn't solve the problem so that improving OS and constructing data backup system should be implemented, This paper proposes the plan to solve that defect in the real system.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.7
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• pp.935-941
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• 2012

This paper describes a study of conventional electrical rig and simulated application of Flywheel Energy Storage system on the power system of the offshore plants with dynamic positioning system with the following aims: improve fuel consumption on engines, prevent blackout and mitigate voltage sags due to pulsed load and fault. Fuel consumption has been analyzed for the generators of the typical drilling rigs compared with the power plant with Flywheel Storage Unit which has an important aid in avoiding power interruption during DP (Dynamic Positioning) operation. The FES (Fly wheel Energy storage System) releases energy very quickly and efficiently to ensure continuity of the power supply to essential consumers such as auxiliary machinery and thrusters upon main power failure. It will run until the standby diesel generator can start and supply the electric power to the facilities to keep the vessel in correct position under DP operation. The proposed backup method to utilize the quick and large energy storage Flywheel system can be optimized in any power system design on offshore plant.