• 전기의세계
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• v.18 no.3
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• pp.7-14
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• 1969

According to the construction of Seoul Thermal #5 (250MW) unit, there will be prospected several new problems on the power system operation. This paper describes the characteristic of system frequency decay during severe emergencies which result in sudden outage of such large generator unit. It also studies the factors involved in applying under frequency relays to maintan an allowable frequency level and to prevent total area collapse by automatic load shedding program.

• Journal of Electrical Engineering and Technology
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• v.2 no.1
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• pp.29-34
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• 2007

The input and output impedances in a low voltage distribution system is one of the most important matters for power line communication because from the viewpoint of communication, the attenuation characteristic of the high frequency signals is greatly caused by impedance mismatch during sending and receiving. The frequency range is from 1MHz to 30MHz. Therefore, this paper investigates the input and output impedances in order to understand the characteristic of high frequency signals in the low voltage distribution system between a pole transformer and an end user. For power line communication, the model of Korea's low voltage distribution system is proposed in a residential area and then the low voltage distribution system is set up in a laboratory. In the low voltage distribution system, S parameters are measured by using a network analyzer. Finally, input and output impedances are calculated using S parameters.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.943-946
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• 1988

A simple method is proposed for determining the frequency response function G(j.omega.) of a system using a pair of characteristic M-sequences (maximum length linear feed back shift register sequence). When a characteristic M-sequence is sampled with q$_{1}$ and q$_{2}$ both of which are coprime with N, where N is the period of the M-sequence, the obtained pair of sequences have conjugate complex frequency spectrum. Making use of this fact, two charcteristic M-sequences having conjugate complex frequency spectrum are applied to a system to be measured. Since the magnitude of spectrium of M-sequence is known, the gain of G(j.omega.) is directly obtained from the Fourier transform of the system output. The phase of G(j.omega.) is obtained simply by taking the average of the two phases of output spectrum.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.11
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• pp.910-914
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• 1991

This paper describes the improvement of frequency characteristic of crystal oscillator I.C using Ti-Salicide. The characteristics of transistor(drive current) using Ti-Salicide process are better than Poly-Si process, because the mobility. To know frequency characteristic of oscillator I.C, the simulation is performed using inverter buffer chain of Fan-out 10 TTL. Its result shows at once the generation of normal clock pulse in input signal and the improvement of rising and falling time.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.4
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• pp.179-187
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• 2001

In recent years, the switching source devices have the advantage of small, light and high reliability with the high-frequency. But, high-frequency switching has disclosed disadvantage of result from stress and turn-on and turn-off peak losses at the switching instant. Accordingly, in this paper propose ZVS-HB type high-frequency resonant DC/DC converter using soft switching technique (Zero-Voltage-Switching, Zero-Current-Switching) with safety operating of circuit at diving on inductive zone, through the circuit design example using the capacitor $C_3,\;C_4$ with soft switching function and division characteristic of resonant Capacitor C, $C_1,\;C_2$, and, the characteristic analysis of circuit is generally described using normalized parameters. Also, this paper certified a rightfulness of characteristic analysis in comparison with a theoretical values and a experimental values obtain from experiment using MOSFET.

• Journal of the Korean Society of Safety
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• v.29 no.2
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• pp.76-81
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• 2014

Railroad traffic accident consists of train accident, level-crossing accident, traffic death and injury accident caused by train or vehicle, and it is showing a continuous downward trend over a long period of time. As a result of the frequency comparison of train accidents and level-crossing accidents using the railway accident statistics data of Railway Industry Information Center, the share of train accident is over 90% in the 1990s and 80% in the 2000s more than the one of level-crossing accidents. In this study, we investigated time series characteristic and short-term prediction of railroad crossing, as well as seasonal characteristic. The analysis data has been accumulated over the past 20 years by using the frequency data of level-crossing accident, and was used as a frequency data per month and year. As a result of the analysis, the frequency of accident has the characteristics of the seasonal occurrence, and it doesn't show the significant decreasing trend in a short-term.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.411-414
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• 2007

In this paper, we studied on characteristic improvement of Balun-BPF using dual-mode ring resonators. The simulated Balun-BPF shows bandwidth of 150MHz at center frequency of 2.45GHz, 4-pole characteristic, return loss of 15dB and symmetrical out-put characteristic.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.42-45
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• 2002

A novel characteristic value extraction method based on morphological spatial frequency is proposed. Morphological spatial frequency defined by morphological pattern distribution function is introduced. Superiority of the method was proved for various images by experiment. Furthermore the fact that the proposed method does not need threshold to obtain binary image provides its applicability to content-based image retrieval.

• Proceedings of the KIEE Conference
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• summer
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• pp.360-362
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• 2004

In this paper, as the preceding research for development of intelligent electronic device for digital based substation automation system, we tried to select the most suitable digital filter by comparison of frequency response characteristic, performance of wanted frequency component extraction.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.113-116
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• 1988

In this paper, We Proposed a new Thyristor-FET hybrid type high-Frequency inverter circuit topology. Concerning the proposed high-frequency inverter. We applied the normalized parameters to the characteristic analysis of steady-state at the resistive load.