• Journal of the Korean Society for Precision Engineering
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• v.15 no.7
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• pp.78-84
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• 1998

The problem of autobody corrosion has been addressed over the past decade by the increasing use of zinc and zinc alloy coated steels in automotive application. This paper describes the evaluation of formability, weldability and painted corrosion performance of galvalume steel sheet. This paper presents an overview of the program and some initial test results on the weldability, lifetime of the electrode tip shape of the spot welding and corrosion protection. Galvalume steel sheet improved corrosion performance and spot weldability of galvalume steel sheet was not changed under the influence of the variation of welding current. And tip shape has influenced on the lifetime of tip for galvalume steel sheet.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.346-349
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• 1997

It is well known that water treeing is one of the main cause of breakdown in underground power cables, but water tree is not easy to observe. This aging phenomenon was resulted in effect of water and electric field and so on. In this paper, Distilled water was used as water electrode to observe the water treeing in XLPE(cross-linked polyethylene). To observe easily, sample was made of pallet types so water tree was able to show by microscope. As a result, electrical tree appears at niddle electrode tip which was concentrated electric field, but water tree was shown up different types that were appealed in total area of water electrode as well as water electrode tip.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.310-315
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• 1997

An extensive corrosion study was initiated by galvalume steel sheet manufacturing company to clarify the corrosion behavior of zinc and zinc and zinc-alloy coated automotive sheet steel in out panel and electrical application. Since the early 1980's the use of zinc and aluminum alloy coated steel for vehicular corrosion protection has increased drastically. This paper describes the evaluation of formability, weldability and painted corrosion performance of galvalume steel sheet. This paper presents an overview of the program and some initial test results on the weldability, lifetime of the electrode tip shape of the spot welding and corrosion protection. Galvalume steel sheet improved corrosion performance and spot weldability of galvalume steel has no problem for the variation of welding current. And tip lifetime was changed according to the influence of shape.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.642-945
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• 1995

The problem of autobody corrosion has been addressed over the past decade by the increasing use of zinc and zinc alloy costed steels in automotive application. this paper describes the evaluation of formability, weldability and painted corrosion performance of galvalume steel sheet. This paper presents an overview of the program and some initial test results on the weldability, lifetime of the electrode tip shpae of the spot welding and corrosion protection. Galvalume steel sheet improved corrosion performance and spot weldability of galvalume steel has no problem for the variation of welding current. And tip lifetime was changed according to the influence of shape.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.8
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• pp.650-657
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• 1989

The conversion efficiency of an ozone generator can be significantly improved by modifying the discharge electrode of a helical strip line rod-to-cylinder type ozone generator to a pyramid-project-embossed rod, and by using a pulse corona discharge. Parametric studies have been carried out to obtain optimum values of peak pulse voltage, pulse forming capacitance, feeder cable and ozone generator capacitance, interelectrode spacing and corona tip density of ozone generator, and feed air flow rate and temperature. The generated ozone concentration was very dependent upon the value of pulse forming capacitance, feeder cable and ozone generator capacitance, and corona tip density. Maximum conversion efficiency was obtained with a pulse forming capacitance of about 500pF, 75pF matched feeder cable and ozone generator, and a corona tip density of 16mm. When operated at optimum values, ozone yield of 79, 99, 80 g/KWh for the different interelectrode type ozone generators tested were obtained, which are approximately 30% higher than that of an industrial ozone generator.

• Geomechanics and Engineering
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• v.30 no.4
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• pp.337-343
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• 2022

The electrical resistivity method is a well-known geophysical method for observing underground conditions, (such as anomalies) and the properties of soil and rock (such as porosity, saturation, and pore fluid characteristics). The shape of electrodes used in an electrical resistivity survey depends on the purpose of the survey and installation conditions. Most electrodes for field applications are cylindrical for sufficient contact with the ground, while some are conically sharpened at their tips for convenient penetration. Previous study only derived theoretical equations for rod-shaped electrodes with spherical tips. In this study, the theoretical resistance for two cylindrical electrodes with conical tips is derived and verified experimentally. The influence of the penetration depth and tip on the measurement is also discussed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.11
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• pp.74-81
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• 2015

In the measurement of atmospheric static electric field, it is important to know characteristics of corona discharges caused at the tip of test electrode. This paper presents the fundamental data of DC corona discharges that occurred at the tip of a needle-shaped electrode placed in the homogeneous background electric field which simulates the atmospheric static field under thundercloud. The major characteristics of interest for this purpose are the polarity effect of corona discharges and the magnitudes and time intervals of corona current pulses. The experimental set-up consists of the plate-to-plate configuration with a needle-shaped protrusion, DC power supply, and voltage and current measuring devices. As a result of experiments, the polarity dependence of corona pulses is significantly pronounced. The time intervals between successive corona pulses in the negative polarity is much longer than those in the positive polarity. The time intervals for both polarities is drastically decreased as the applied electric field is increased. Also the magnitudes of the positive corona pulses are slightly changed with an increase in applied electric field, but those of the negative corona pulses are linearly increased with increasing the applied electric fields.

• Journal of the Korean Chemical Society
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• v.11 no.3
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• pp.81-84
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• 1967

A simple rotating micro mercury electrode is constructed in such a way that the mercury surface can be renewed quite easily with reasonable reproducibility. It consists of a glass capillary of about 1mm diameter connected to a mercury filled tube by means of a ground joint that allows mercury flow at a particular relative position only, and the electrical connection between the two parts is made by a platinum wire fused in the bottom of the latter. Thus the mercury surface exposed at the tip of the capillary replaces the platinum tip of the usual platinum micro electrode; however, the capillary has to be bent so that the tip directs upwards. It has been found to be a convenient electrode in the amperometric titration in strongly acidic media. Furthermore, it has been advantageously used in the alternating-current polarography because of its smaller electrical resistance than the ordinary dropping mercury electrodes. It also can be used as a stationary mercury electrode in fast scanning polarography.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.508-512
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• 2004

An ultra-sharp tungsten electrode for field emission was manufactured by using an electrochemical etching method, and its beam characteristics were investigated. KOH and NaOH were the electrolytes used in this research, and the taper length of the tip varied form 150 $\mu\textrm{m}$ to 250 $\mu\textrm{m}$ according to the applied voltage and the concentration of the electrolyte. The electron-beam stability was measured to be within 5% for a total emission current of 5 ${\mu}\textrm{A}$ during 4 hours of operation, and the Ignition voltages were found to be ∼300 V. The tip radius was experimentally found to be 250${\AA}$ from a linear fitting of Fowler-Nordheim plots, which was in remarkably good agreement with that of the image size from scanning ion-microscopy.

• Journal of Welding and Joining
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• v.5 no.3
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• pp.11-18
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• 1987

Effects of electrode tips shapes of spot welding on the galvannealed steel have been studied, and the results obtained from this studies are as follows. 1) Expulsion had no effect on the shear strength of the specimen but been observed on the tensile strength of the specimen. 2) Effect of holding time after welding was neglegible when the spot welding supplies enough heat input. 3) Depending on the sopt welding tip shape it has different weldbility. It has better weldability in the order of pointed shape, truncated shape and dome shape. But the effect of coolind was just the opposite of the above order.