• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.3008-3020
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• 1994

Condensation heat transfer on a single horizontal tube with electric fields (Electro-Hydro-Dynamics, (EHD)) has been studied experimentally. Results are presented for EHD enhanced condensation of R-113 on a single horizontal tube using several electrode geometries. Especially, its attention was focused on the effects of electrode geometry, electric field strength and the gap of the electrode. In this study, single wire, helical, ring and mesh electrode were used. The range of the imposed voltage was 0~20 kV. As the voltage was increased the surface of liquid became an unstable wave, stream jet, liquid column and then liquid extraction in sequence. Among the various kinds of electrodes, the single wire electrode is suitable for practical application.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.233-236
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• 2000

A portable equipment that measures a current and voltage waveform of power transmission lines is pro-posed. In the equipment, the current and voltage, respectively, are detected by a loop coil and a capacitor clamped around the power lines. The detected data is transmitted by an FM wave to the receiver on the ground station. Since the receiver is isolated from the power lines, we do not require high potential insulators for the measurement of current and voltage. The proposed equipment is therefore, small-sized, light, and low in the cost of production. Experimental results presented here show that the equipment can monitor the current flowing in single wire over a ground plane and the potential of the wire.

• Journal of the Semiconductor & Display Technology
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• v.19 no.2
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• pp.110-114
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• 2020

In this paper, a heat pump using a Peltier device was developed for heat dissipation in a sealed electric box. The heat pump was designed with a cooling fin attached to both sides of the Peltier device, and a fan was mounted on the cooling fin on the hot side to increase the efficiency. The heat dissipation efficiency could be improved by directly connecting the electronic component having high heat to the cooling fin using a heat conducting wire. The fabricated heat pump was designed to operate only in the temperature range set by the temperature control system to improve the problem of high power consumption of the Peltier element.

• Journal of Power Electronics
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• v.14 no.4
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• pp.764-777
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• 2014

This study analyzes the mathematical relationship between DC-link voltage and system parameters for shunt active power filters (APFs). Analysis and mathematical deduction are used to determine the required minimum DC-link voltage for APF. A novel adaptive DC-link voltage controller for the three-phase four-wire shunt APF is then proposed. In this controller, the DC-link voltage reference value will be maintained at the required minimum voltage level. Therefore, power consumption and switching loss will effectively decrease. The DC-link voltage can also adaptively yield different DC-link voltage levels based on different harmonic currents and grid voltage levels and thus avoid the effects of harmonic current and grid voltage fluctuation on compensation performance. Finally, representative simulation and experimental results in a three-phase four-wire center-split shunt APF are presented to verify the validity and effectiveness of the minimum DC-link voltage design and the proposed adaptive DC-link voltage controller.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.376-378
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• 2003

Since the first underground transmission line of Korea was installed between Danginri and Yongsan substations in 1974, the two types of underground transmission power cables, oil-filled and XLPE, have been applied for underground transmission lines. As the manufacturing technologies of XLPE cable have been improved and the simplicity of installation and maintenance has been focused on, the installations of XLPE cables have been largely increased since the mid 1990's. For the first time, in Korea, the 345kV XLPE cable was installed between Youngseo and Youngdeungpo substations in 2003, June. So, this paper introduces the project profile, the design of cable and its accessory, the cable system design, installation and site test.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.615-618
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• 2003

To investigate the electrical fire identification due to conductor structure analysis of an electrical wire, we are studied by temperature heating test, over current test, short test and electric molten marks. And metal structure analysis of wire by short, we are found out increase in crystal grain with heating temperature. Structure of specimen at over current 300[%] occurred hardly structure formation and boundary of grain.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.6
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• pp.512-515
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• 2019

Overhead contact systems (OCS) consist of contact and messenger wires, in which the contact wire supplies electric energy to the railway vehicle by contacting a pantograph. However, this mechanical contact is interrupted during frosts or temperatures below $0^{\circ}C$ in the winter. In these conditions, railway vehicle accidents can occur during operation because of the low energy efficiency that results from the increase in the arcing between the contact wire and pantograph. Therefore, the detection of frost or freezing temperatures is necessary to maintain the stable operation of these trains. In this study, we proposed the development of a frost or freezing condition monitoring system on the OCSs that utilizes wireless communication.

• Composites Research
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• v.13 no.6
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• pp.39-46
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• 2000

Electrical discharge machining (EDM) cuts metal by discharging electric current across a thin gap between tool and workpiece. Electrical discharge wire cutting, a special form of EDM, uses a continuously moving conductive wire as an electrode, and is widely used for the manufacture of punches, dies and stripper plates. In the wire cutting process, the moving wire is usually supported by cantilever arm and wire guides. As the wire traveling speed has been increased in recent years to improve productivity, the vibration of the cantilever arm occurs, which reduces the positional accuracy of the machine. Therefore, the design and manufacture of the cantilever arm with high dynamic characteristics have become important as the machining speed increases. In this paper, the cantilever arm for guiding the moving wire was designed and manufactured using carbon fiber epoxy composite in order to improve the static and dynamic characteristics. Specimens for the composite cantilever arm were manufactured and tested to investigate the effect of the number of reinforcing plies and length fitted to steel flange on the load capacity. Also, the finite element analysis using layer and contact elements was performed to compare the calculated results with the experimental ones. From the results, the prototype of the composite cantilever arm for the electrical discharge wire cutting machine was manufactured and the static and dynamic characteristics were compared with those of the conventional steel cantilever arm.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.4
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• pp.543-548
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• 2016

Live-line maintenance for electric power lines is very dangerous because of their ultra-high voltage environments and the risks of falling from heights. Recently, drone technology has been spotlighted due to its maneuverability and stable controllability, and has been being applied to maintenance works in the electric power industry. This paper presents a new type of drone that can be transformable by introducing biomimetics to its mechanism and can run on an overhead ground wire as well as it can fly. Its technical feasibility was confirmed through experiments.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2002.05a
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• pp.127-132
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• 2002