• The Korean Journal of Ceramics
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• v.5 no.4
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• pp.386-389
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• 1999

Effect of high voltage screening was examined on mechanical strength of titania ceramics with two different surface roughness. Roughly finished sample showed degraded mechanical strength meaning that the introduced flaw played the role of starting point of mechanical fracture. On such sample, electrically weak parts were eliminated by applying a screening field. Mechanical strength measurement on survived parts revealed that after screening the Weibull plots bended to become a convex curve while plots at high strength region were almost the same. This result means that relatively low mechanical strength parts were eliminated by the electrical method. As a result the Weibull modulus calculated from all the data increased, demonstrating the effect of high voltage screening on titania ceramics containing fracture controlling surface flaws. Roles of the surface flaw such as a common weak spot for both failures are disscussed in relation to the electric field concentration similar to that of mechanical stress.

• Journal of computational fluids engineering
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• v.15 no.3
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• pp.9-15
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• 2010

In this study, we calculated arc discharges and flow characteristics driven by arcs in a thermal puffer chamber, which is one of most outstanding high-voltage interrupters, for understanding the complex physics and the probability of thermal breakdown. The four main parts of arc model for this virtual-reality are radiation, PTFE ablation, Cu evaporation, and turbulence. Among these important parts the turbulence model can be critical to the reliability of computation results during the whole arcing history because the plasma flow is affected by high heat energy and mass momentum. Two turbulence models, the Prandtl's mixing length model and the standard $k-\varepsilon$ model, are applied for these calculations and are compared with pressure-rise inside chamber and arc voltage between the contacts as well as flow characteristics near current zero.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.201-207
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• 2010

In this study, we calculated arc discharges happened in high-voltage circuit breakers for understanding the complex physics and the probability of thermal breakdown. The four main parts of arc model for this virtual-reality are radiation, PTFE abaltion, Cu evaporation and turbulence. Among these important parts the turbulence model can be critical to the reliability of computation results during high-current period because the plasma flow is affected by high eat energy and mass momentum. Two kinds of turbulence model, zero-equation model and two-equation model, are applied for these calculations and are compared with the measured pressure data inside a chamber.

• Journal of Powder Materials
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• v.10 no.3
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• pp.151-156
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• 2003

In the present work some properties of nanopowders and possible areas of their applications are discussed. Main attention is paid to the use of nanodispersed powders (NDP) in new materials production technologies.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.6
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• pp.1591-1601
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• 2016

In recent years most of large-sized merchant ships have been equipped with a high-voltage system. The ships demanding a lot of electric power adopt the high voltage such as 3.3kV, 6.6kV, 11kV. Gradually as the high voltage system is increased in the ships, engineering officers are more opportunities to operate the high voltage system. So the high voltage training for engineering officers was established in the STCW 1978 as amended by the Manila Amendments in 2010. According to this convention when the engineering officers want to board the high voltage ships on and after January 1 in 2017, they must take the high voltage training. This paper, firstly, analyzes the content of high voltage training in STCW convention and IMO model course. In addition, it reviews the parts need to be considered in the content of the high voltage training. Finally this paper proposes the contents of training model divided into theory and practice.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.405-408
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• 1989

A 1800KV testing chamber for gas insulation has been developed. To develop the chamber, all parts consisting of the chamber, namely, bushing, main chamber, shield, conductor bus, inspection window, feedthrough, and spacer have been designed based on numerical electric field analysis. This paper presents the detailed design philosophy and methods of the chamber.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.577-580
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• 2000

The aim of this paper is to develop a high stable measuring device for radioactive pulses. The device consists of a high voltage supply unit using a fly-back converter principle, and a pulse detection unit for gamma-rays and neutrons. The high voltage supply unit designed can generate DC voltage up to 1,500v at 5V-input, and have a series voltage regulator to maintain the output voltage constantly, resulting in less than 1.63% of voltage regulation. The pulse detection parts consists of an active integrator, a pole-zero circuit, and a 3-stage amplifier of 60 dB, and its frequency bandwidth is from 37 Hz to 300 kHz. From the experimental results, it is confirmed that the measuring device can count at least 10,000 pulses in a second.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.459-460
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• 2006

Electron beam manufacturing system can be used to make patterns that are smaller than can a photolithography. In this system, High voltage generator is a fundamental element for stable beam. We used high voltage with transformer. However, this instrument has several problems (for examples, dimensions, buying parts, simplicity of control circuit). For solving these problems, a commercial product is considered. This is developed for SEM(Scanning Electron Microscope). In this paper, we designed a control circuit for a commercial product and analyzed performance.

• Corrosion Science and Technology
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• v.18 no.4
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• pp.117-120
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• 2019

Considering the tendency of development of electrification vehicles, development and verification of new evaluation technology is needed because of new technology applications. Recently, as the battery package is set outdoors of an electric vehicle, such vehicles are exposed to corrosive environments. Among major components connected to the battery package, rust prevention of high-voltage cables and connectors is considered the most important issue. For example, if corrosion of high voltage cable connectors occurs, the corrosion durability assessment of using an electric vehicle will be different from general environmental corrosion phenomena. The purpose of this study is to investigate the corrosion mechanism of high voltage cable connectors of an electric vehicle under various driving environments (road surface vibration, corrosion environment, current conduction by stray current, etc.) and develop an optimal rust prevention solution. To improve our parts test method, we have proposed a realistic test method to reproduce actual electric vehicle corrosion issues based on the principle test.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.2
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• pp.238-244
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• 2010

In this paper, we studied electrical characteristics of internal converter type of LED lamps for road and street lighting. We surveyed electro-technical regulations and KS(Korean industrial standards) about LED luminairs. Waveforms of voltage and current, thermal distributions, insulation resistances between live parts and exposed conductive parts, and flame test of cover of LED lamps were experimented and analyzed. In regulations, insulation resistance between live conductors and exposed conductive parts should be greater than $0.2M{\Omega}$ in case nominal voltage of wiring is 220V. In KS codes, the value of insulation resistance should be greater than $2M{\Omega}$ while applying DC 500V or DC 100V. In the result of this study, waveforms of primary voltage and current were distorted. There was difference in waveforms of secondary voltage and current according to composition of converter. Mostly, insulation resistances were measured high more than regulation and code value but some measured points were measured badly($0.0M{\Omega}$). Cover of LED lamps was ignited easily. We expect that the results of this study would be helpful for revision of regulations and national codes for the electrical safety of LED road and street lighting.