• Proceedings of the KIEE Conference
• /
• 2003.07a
• /
• pp.323-325
• /
• 2003

A current differential relay may maloperate for external faults with CT saturation and requires an additional method to cope with the problem. This paper proposes a current differential relaying algorithm for transmission line protection using an advanced compensation algorithm of the secondary current of CTs. The compensation algorithm is unaffected by a remanent flux. The proposed algorithm does not need an additional method for CT saturation and thus can achieve high stability for an external fault.

• Proceedings of the KIEE Conference
• /
• 2003.07a
• /
• pp.338-341
• /
• 2003

This paper proposes the adaptive relaying algorithm of protective devices applied in the neighboring distribution feeders for reliable and efficient operations of a wind farm interconnected with distribution networks by dedicated lines. Generally, it would be highly possible that the wind turbine generators are influenced by abnormal grid conditions such as disturbances occurring in the neighboring distribution feeders as well as the dedicated power line. The delayed operation time of protective devices for satisfying the coordination might overly expose the interconnected wind turbine generators to the fault and cause damage to them. In order to reduce the damages on the interconnected wind farm about the faults happening in distribution networks, this paper describes the proper delayed operation time of protective relay.

• Journal of the Semiconductor & Display Technology
• /
• v.10 no.1
• /
• pp.101-105
• /
• 2011

In case of high-tech process industries such as semiconductor and TFT-LCD manufactures, fault of a virtually finished product that is value-added one, since it has gone throughout the most of processes, may give rise to quality cost nearly amount to its selling price and can be a main cause that decreases the efficiency of manufacturing process. This paper proposes a real-time dispatching algorithm for semiconductor manufacturing process with rework. In order to evaluate the proposed algorithm, this paper examines the performance of the proposed method by comparing it with that of the existing dispatching algorithms, based on various experimental data.

• Proceedings of the KIEE Conference
• /
• 1996.07b
• /
• pp.677-679
• /
• 1996

This paper describes a method to improve the speed of a distance relay based on a differential equation of transmission lines using feedforward artificial neural networks (ANN) on an EHV system. For the impedance calculation an integration approximation to the differential equation is used and then an ANN is trained with the impedance convergence characteristic. The ANN predicts the fault distance with some calculated resistances and reactances before they reach trip zone. Thus, the proposed method can improve the speed of distance relays, significantly if a high sampling rate such as 48 samples per cycle is employed.

• Proceedings of the KIEE Conference
• /
• 1993.07a
• /
• pp.180-182
• /
• 1993

A distance protection algorithm for detecting faults at power transmission lines is presented in this paper. The algorithm is based on the differential equation related to the voltage and the current at an equivalent circuit of a transmission line which is composed of the lumped resistance and inductance. The presented integration method has high performance at though the fault voltage and the current are heavily distorted with the DC offset and harmonics which occurred at transient states after faults.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.7
• /
• pp.937-943
• /
• 2012

Most of faults occurred in transmission lines are single-phase to ground faults and transient faults. Single-phase auto reclosing is an appropriate scheme to maintain the system stability and restore the system effectively when those faults are occurred. In single-phase auto reclosing scheme, the secondary arc is generated after faulted phase is tripped to eliminate the fault and it is sustained by the capacitive and inductive coupling to the healthy phases. It is important to reclose the faulted phase after fully extinction of secondary arc because of the damage applied to system. Therefore, it is necessary to research on the detection of secondary arc extinction to ensure high success rate of reclosing. In this step, firstly, the accurate modelling of secondary arc should be performed. In this paper, the modelling of secondary arc is performed by using EMTP-RV and the simulation results show that the implemented model is correct and effective.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.1453-1454
• /
• 2007

A street light is an electrical equipment to improve the traffic safety and the security for people in night. However, many accidents due to electric shock have happened in recent, people were interested in the safety of electrical facilities. And people want to know the danger by touch and step voltages. When the electric power lines fall down on the ground, the fault current flows to ground rod and the potential near the ground rod is increased to induce the high touch and step voltages. In this paper, we installed different ground rods with a street light and investigated the electrical potential according to ground methods and the types of ground rod. Finally, we examined the electrical facilities with the experimental result and present the improved technical data for the safety from electric shock

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.397-399
• /
• 2004

A small-sized isolated 154kV transmission system could be brought out by a separation from whole network due to faults at transmission lines. For such system, where a fault occurs following a reclosing action, we Provided the basis for study to provide an effective load shedding scheme needed to the case of failure of reclosing action as well as the characteristic of reclosing action whether it succeeds or fails.

• Proceedings of the KIPE Conference
• /
• 2018.11a
• /
• pp.9-11
• /
• 2018

This paper studies on the development of an electric fire prevention system with the detection and alarm in case of parallel arc fault occurrence in low voltage distribution lines. The proposed detector has the characteristics of high speed operation responsibility and superior system reliability from composition using a large number of semiconductor devices. The line voltage is always feedback, and when an arc or a spark occurs, these are detected by the microcomputer. In addition, we design and develop algorithms using high speed and high precision microcomputer. A new conceptual control technique is adopted that RCD cuts-off by forming a forced short circuit between the phase voltage and ground in the event of an electrical accident. Some experimental tests of the proposed system also confirm practicality and the validity of the analytical results.

• Journal of the Korean Geophysical Society
• /
• v.3 no.4
• /
• pp.215-226
• /
• 2000

In order to map the acoustic basement and to locate fracture zones in the Galgok fault, seismic refraction data were acquired near the Chonbuk ranch in Gyeongju. Along three profiles of 72m(Line 1), 72m(Line 2), and 36m(Line 3) long, seismic signals were generated by a 5kg hammer. The refraction data were collected by employing twelve 8 Hz geophones at an interval of 3m and recording time of 192ms at a sampling rate of 0.2ms. The data are interpreted using GRM method. The top layer (Layer 1) is characterized as the velocity of approximately250 m/s and thickness of approximately 2.1m. This layer is regarded as a soil layer. Underneath Layer 1 lies unconsolidated layer (Layer 2) whose refraction velocity is determined to be $1,030{\sim}1,400m/s$. Layer 2 is approximately 4.6m thick and is regarded as a Quaternary gravel layer. The third layer (Layer 3) has the mean refraction velocity of $2,100{\sim}2,200m/s$ and is interpreted to be the acoustic basement. In some parts of Lines 1 and 3, the difference in depth to the top of Layer 2 is greater than 20 cm indicating the possibility of existence of Quaternary faults. Along Line 3 and the eastern part of Line 1, refracted energy from the acoustic basement was not recorded. This may highly indicate that a relatively large scale fault exists under the western part of Line 1.