• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.57-60
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• 2001

This paper presents a new method for removing reaching phase in variable structure control systems using Bell type switching function. By proposed method, during the entire control process reaching phase is removed. For effective speed control of trapezoidal type brushless DC motor, a time varying switching function based speed controller is developed as illustration.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.9 s.174
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• pp.7-13
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• 2005

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.93-93
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• 2006

• Proceedings of the Korean Nuclear Society Conference
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• 1998.10a
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• pp.210-210
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• 1998

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.345-346
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• 2002

The electrical and rheological properties of a chitosan malonate suspension in silicone oil was investigated by varying the electric fields, volume fractions of particles, and shear rates, respectively. The chitosan malonate susepnsion showed a typical electrorheological (ER) response caused by the polarizability of an amide polar group and shear yield stress due to the formation of multiple chains upon application of an electric field. The shear stress for the suspension exhibited a linear dependence on the volume fraction and an electric field power of 1.88. On the basis of the results, the newly synthesized chitosan malonate suspension was found to be an anhydrous ER fluid.

• Progress in Superconductivity
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• v.11 no.1
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• pp.19-24
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• 2009

Among the various types of fault current limiters, superconducting fault current limiters could be the most preferable choice for high voltage electric power systems owing to the remarkable current limiting characteristics of superconductors. But, there have been no commercial superconducting fault current limiters which were installed into actual electric power systems until these days due to some remained technical and economical problems. Thus, in order to promote the development and application of the superconducting fault current limiters into real field, it is essential to understand the power utilities’ requirements for their networks and also suitable test method and some specifications should be prepared. This paper focuses on the matters of test requirements and standardization issues that should be prepared for commercialization of superconducting fault current limiters. The unique current limiting characteristics of superconducting fault current limiters were investigated and related other standards including circuit breakers, transformers, reactors, power fuse, and fused circuit breakers were compared to setup the basis of novel specification of superconducting fault current limiters. Furthermore, required essential test procedures for superconducting fault current limiters were suggested.

• KSTLE International Journal
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• v.2 no.1
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• pp.71-74
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• 2001

The electrorheological(ER) performance of a chitosan sebaciate suspension in silicone oil was investigated by varying the electric fields, volume fractions of particles, and shear rates, respectively. The chitosan sebacicate susepnsion showed a typical ER response caused by the polarizability of an amide polar group and shear yield stress due to the formation of multiple chains upon application of an electric field. The shear stress for the suspension exhibited a linear dependence on the volume fraction of particles and an electric field power of 1.88. On the basis of the results, the newly synthesized chitosan sebacicate suspension was found to be an anhydrous ER fluid.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1425-1427
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• 1998

The thermal history of XLPE insulated cable during heating cycle voltage test specified by IEC 840 was examined by DSC(differential scanning calorimetry) method, of which the principal is on the basis of the phenomenon that the crystals in polyethylene are rearranged as it is annealed near/below the melting temperature. From the result, it can be estimated that XLPE insulation near the conductor was exposed at the temperature of about $100^{\circ}C$ with the electrical stress through the test.

• KSTLE International Journal
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• v.3 no.1
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• pp.23-25
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• 2002

The electrorheological (ER) behavior of amino coated chitosan phosphate suspension in silicone oil is investigated. Amino coated chitosan phosphate suspension shows a typical ER response (Bingham flow behavior) upon application of an electric field due to the polarizability of phosphoryl polar group. The shear stress for the suspension exhibits a linear dependence on an electric field power of 1.94. The values of structure factors $A_s$obtains 2 far mine coated chitosan phosphate suspension and it may be due to the formation of multiple chains upon application of the electric field. Throughtout the experimental results, amino coated chitosan phosphate suspension shows good dispersion stability and found to be an anhydrous ER fluid.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1907-1909
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• 1996

In this paper, ultrsonic detection properties at a premolde joint utilized in a 23kV cables are studied. In a experiment a artificial defect within a joint and a measuring system are builded for generating discharges, gathering data about a detection properties, respectively. The experiment results show that one point detection is not allowed for monitoring a global status of a joint discharges and a detection sensitivity is less than 100pC. And also the attenuation and wave speed at the material of joint insulator are obtained.