• Proceedings of the KIPE Conference
• /
• 2019.11a
• /
• pp.106-107
• /
• 2019

This paper propose a new 3D SVM method for three-phase four wire inverter for fault isolation at a single line ground fault. The available switching combination for isolation of a single line ground fault was analyzed. Using this method, voltage vector diagrams according to each switching combination were classified according to various ground fault situations, and 3D SVM method was performed by generating command for fault isolation. The proposed methods are mathematically analyzed and verified by PSIM simulation.

• Proceedings of the KIEE Conference
• /
• 2006.10a
• /
• pp.196-197
• /
• 2006

An effective method is described for monitoring the ground impedance of intelligent building and power system. Most of grounding system of buildings are interconnected to extensive grounding network of power line, signal and control line, telecommunication line, and etc. Therefore, the residual voltages of power frequency and its harmonics may have an significant influence on the accurate measurement of ground impedance. For eliminating the influence of residual voltage, we developed a test power source for generating the 110[Hz] square wave and used digital filtering method in this research.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.24 no.1
• /
• pp.74-81
• /
• 2016

The aim of this study was to find the initial design value of turbine blade for electrical type turbocompound system generating 10 kW. Turbocompound is one of the waste heat recovery system applying to internal combustion engine to recover exhaust gas energy that was about 30 % of total input energy. To design the turbine blade, 1-D mean line flow model was used. Exhaust gas temperature, pressure, flow rate and turbine rotating speed was fixed as primary boundary conditions. The velocity triangles was defined and used to determine the rotor inlet radius and width, the rotor outlet radius at shroud and radius at hub, the rotor flow angles and the number of blades.

• Journal of Electrical Engineering and Technology
• /
• v.4 no.3
• /
• pp.346-352
• /
• 2009

The eventual goal of this paper is to help the generating companies and load-serving entities to choose appropriate relative levels of interconnected system versus bilateral trades while considering risk, and economic performance. In competitive power markets, electricity prices are determined by balance between demand and supply in electric power exchanges or bilateral contracts. The problem formulation is bilateral contract incorporated into Multi-area unit commitment with import/export and tie-line constraints. This proposed method considers maximizing own profit or minimize the operating cost among the generating companies in multi-area system. The feasibility of the proposed algorithm has been demonstrated using IEEE system with four areas and experimental results shows that proposed method is reliable, fast and computationally efficient

• Proceedings of the Korea Water Resources Association Conference
• /
• 2005.05b
• /
• pp.532-537
• /
• 2005

The techniques of internally generating waves on a curve in a rectangular grid system are developed using the line source method. Numerical experiments are conducted using the extended mild-slope equations of Suh et al. (1997). For five different types of wave generation layout, numerical experiments are conducted in the cases of the propagation of waves on a flat bottom, and the refraction and shoaling of waves on a plane slope. The fifth type of wave generation, which consists of two parallel lines connected to a semicircle, shows the best solutions especially when the grid size is small enough.

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

• Proceedings of the KIEE Conference
• /
• 1992.07b
• /
• pp.1035-1037
• /
• 1992

Generally, fuel cell has characteristics of low voltage, large current and voltage variation under load change. Therefore, DC output voltage of fuel cell is too low to convert into AC with high efficiency and good performance. For this reason, fuel cell generating system is composed of DC-DC converter and inverter in cascade. This paper used 2-phase boost DC-DC converter to obtain low distortion waveform and reduce input-output current ripple, and discussed inverter which can be operated in independent drive mode and utility line interface drive mode. Then, the change of modes can be achived smoothly.

• Proceedings of the KIEE Conference
• /
• 2006.07a
• /
• pp.268-269
• /
• 2006

Auto-synchonizer is important device to match the voltage, frequency, phase of the generating system to those factors of the transmission line, when the synchronous generator is operated. There were few or no incidents by Synchronization failure at Hapcheon hydraulic power plant, since it was built in 1989. but incidents by Synchronization failure have often happend lately. From now, let's improve the efficiency on the maintenance of generating equipment by studying about the cause and the method for this problem by comparing with the set point of each device of synchronizing system.

• Agricultural and Biosystems Engineering
• /
• v.2 no.1
• /
• pp.15-23
• /
• 2001

On the assumption that the voices of the cows are produced by the linear prediction filter, we characterized the cows’voices. The order of this filter was determined by examining the voice characteristics both in time and frequency domains. The proposed order of the linear prediction filter is 15 for modeling voice production of the cow. The characteristics of the amplitude envelope of the voice signal was investigated by analyzing the sequence of the short time variance both in time and frequency domains, and the new parameters were defined. One of the coefficients o the linear prediction filter generating the voice signal, the fundamental frequency, the slope of the straight line regressed from the log-log spectra of the short time variance and the coefficients of the linear prediction filter generating the sequence of the short time variance of the voice signal can differentiate the two cows.

• Proceedings of the KIEE Conference
• /
• 2004.11b
• /
• pp.275-277
• /
• 2004

Although Jeju island Is connected with main network system by HVDC cable line, it's network assumes the form of independent system in an operating point of view. Therefore Jeju needs it's own independent capacity expansion planning. Continuos growth of demand and increase of antiquated plants in Jeju requires additional generating capacity. This paper analyzes characteristics of two alternatives which include it's own expansion of facilities and capacity expansion of network system for Jeju island. Furthermore this paper evaluates economic efficiency of those alternatives and analyzes long-term program of demand-supply of electricity.