• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.447-450
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• 2002

Recently polymeric insulators and arresters are being used for outdoor high voltage applications. Polymeric insulators for transmission line have significant advantages over porcelain and glass insulators, especially for ultra-high voltage(UHV) transmission lines. Their advantages are light weight, vandalism resistance and hydrophobicity. Polymeric insulator kind are a relatively new technology, but their expected life is still unknown. In this paper, the material property for polymeric insulating material such as silicone rubber and EPBM is investigated by cross-link time and the relation between tracking resistance and W resistance is analyzed by IEC 60587 and W aging experiment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.10
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• pp.1114-1119
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• 2004

The photodepositioned tungsten film by laser CVD has been carried out the taping test with scotch tape over 10 times. As a result, it exhibited strong adhesion to the under-film such as ITO and SiNx patterned on the LCD substrate. However, it was seriously attacked by alkaline solution used for removing polyimide. And a thickness of laser CVD tungsten film had a close relation to a speed of laser scanning. Also we have improved the success rate of a laser CVD repair with making two pairs of contact hole structure and decreasing laser scanning speed.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.469-470
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• 2007

In this paper, we propose a simple and relative electrode contact monitoring method. By exploiting the power line interference, which is regarded as one of the worst noise sources for bio-potential measurement, the relative difference in electrode impedance can be measured without a current or voltage source. Substantial benefits, including no extra circuit components, no degradation of the body potential driving circuit, and no electrical safety problem, can be achieved using this method. Furthermore, this method can be applied to multi-channel isolated bio-potential measurement systems and home health care devices under a steady measuring environment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.524-527
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• 2000

In this paper, we have studied minimization of the burr which occurred after $\mu$-BGA(ball grid array) singulation process, singulation of the multilayer with a pulsed Nd:YAG(266, 532 nm) laser is used to cut the metal layer which doesn't well absorb laser beam. Especially, the photoresist and $N_2$blowing is effective to minimize of the surface demage and burr. In this experiment, the $N_2$ blowing reduces a laser energy loss by debris and suppress a surface oxidation. The SEM(scanning electron microscopes) and non-contact 3D inspector are used to measure cutting line-width and surface demage. The $\mu$-BGA singulation threshold energy is 75.0 J/cm$^2$at 30 ${\mu}{\textrm}{m}$/s scan speed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.640-643
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• 1999

This paper presents the results of multi-stress chamber experiments done to examine the tracking and erosion performance of polymer insulator. Multi-stress testing is able to demonstrate deficiencies of polymer insulator materials and designs, including the nature of interfaces in insulation design. Therefore, multi-stress testing is believed to a suitable test for evaluating the aging performance of polymer insulator designs. We have nvestigated IEC 61109 Annex C for estimating long time performance of polymer insulator.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.12
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• pp.1711-1716
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• 2018

Unlike conventional transmission and distribution lines, catenary system for operating electric railway vehicles are composed of multi-conductor groups (feeder line, contact wire, messenger wire, protection wire) and are used for railway employees, public or passengers in the station yards. Electric shock hazards are exposed and electric shocks such as death or serious injury are occurring in electric railway vehicles, railway high-voltage distribution lines, and catenary system. In order to analyze the types of electric shock accidents on railway by systematic approach method, we modeled 'unsafe behavior classification' method using swiss cheese model. Based on this method, we derived the type of electric shock accidents about railway accidents during the last 5 years by analyzing the frequency of occurrence of human errors and unsafe acts, laws and regulations related to violations, and so on.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.674-679
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• 2011

In this paper, we experimented and analyzed about electric fire risk assessment methods of LED lightings for outdoor. LED lighting is composed of AC power lines, AC/DC converter, DC power lines and LED lamps. There are some risk factors of electric fire in LED lighting such as short circuit between power lines or power line and ground, dielectric breakdown, leakage current, abnormal voltage inflow, poor contacts(connections), etc. As a result of this study, insulation coverings of wire was ignited due to dielectric breakdown between power lines and molten marks were formed in copper conductor. LED lighting was blown out while short circuit, beside that, electrical disorder did not occur. When abnormal voltage was inflowed, electronic components such as varistor, condenser were damaged. Partial heating was produced and insulation was melted and carbonized by arc and heating while poor contacts were happened. We expect that the results of this study would be helpful for electrical safety of LED lightings for outdoor.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.152-154
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• 2001

Recently the extensive use of composite insulators for transmission lines can ultimately be justified only on long-term qualification tests. Especially, it is possible for the Polymer insulator to be aged in according to the environment in which it is used this may bring about the decrease of the duration of voltage application. So, this paper deals with aging property of the polymer insulator installed at real transmission line in the industry area. The contact angle, arc test, tracking test were measured for acquiring the degradation characteristics of silicone rubber and the SEM, XRF, FT-IR tests were measured for analyzing the crack and components. Also the surface leakage current of the polymer insulator was compared with that of the porcelain insulator. Finally, we knew that the aging property was not appeared during seven months at real transmission line in the industry area.

• Journal of Adhesion and Interface
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• v.18 no.1
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• pp.1-7
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• 2017

This study is about basic sensor experiment using PDPS by common pencil. 20 mm length, 3 mm thickness of line using 4B pencil is optimum condition. In order to be stable at point of contact between pencil line and copper wire, silver paste is needed. At using the PDPS, thermal detecting is able and thermal properties is inversely proportional to electrical resistance in the based on empirical formula. The sensor can be also used in the composites mold via the empirical formula by the relationship between thermal impact and electrical resistance. The change of electrical resistance relates the interfacial property of composites. It leads to expectation of properties.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.9
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• pp.8-13
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• 2014

Currently it is major problem of electric railway with increasing drive speed such as the arc generated by the pantograph detachment and the distortion current in the motor-block high speed switching. When physical contact between the pantograph and the catenary line is separated, the pantograph detachment arcing occurs and it makes up the conductive noise to the return feeder. We made the EMTP modeling of the railway traction system and the pantograph arc by circuit elements and switches. The influence of pantograph detachment frequency is investigated by changing some frequencies. The over-current occurs in each detachment and it oscillates some time at beginning and stabilizes gradually. The magnitude of over-current is decided by instantaneous value of existing traction return current. If the detachment occurs at a point of peak value or distortion current, the over-current will be more harmful to the power systems connected with the return feeder and will become to arise with increasing detachment frequency.