• The Transactions of the Korean Institute of Electrical Engineers P
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• 제58권4호
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• pp.511-515
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• 2009

For detecting of the faulty insulator, Correlation Propagation Neural Networks(CPNN) has been proposed. Faulty insulator is reduced the rate of insulation extremely, and taken the results dirty and injured. It is necessary to detect the faulty insulator and exchange the new one. And thus, we have designed the CPNN to be detected that insulators by the real time computation method through the inter-node diffusion. In the network, a node corresponds to a state in the quantized input space. Each node is composed of a processing unit and fixed weights from its neighbor nodes as well as its input terminal. Information propagates among neighbor nodes laterally and inter-node interpolation is achieved. 1-D CPNN hardware has been implemented with general purpose. Experiments with static and dynamic signals have been done upon the CPNN hardware. Through the results of simulation experiments, we define the ability of real-time detecting the faulty insulators.

• Proceedings of the Polymer Society of Korea Conference
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.373-373
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• 2006

Rigid polyurethane foams(PUFs) are widely used in most areas of insulations such as storage tank and pipe line for transporting liquefied gas. Glass fiber and nanoclay are used for improvement in mechanical property and thermal insulation of rigid PUF at very low temperature(<$-150^{\circ}C$). These rigid PUFs have been characterized in terms of thermal, mechanical, dynamic mechanical properties and cell morphology. It was found that mechanical properties, thermal conductivity and dimensional stability of rigid PU foams were improved by glass fiber and nanoclay.

• Proceedings of the KIEE Conference
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1670-1672
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• 1996

Silicone rubber composite is very suitable for insulation materials because of it's hydrophobicity, mass productivity, and design flexibility. A study of the diffusion of silicone fluid from the bulk to the surface of the silicone rubber composite using dynamic contact angle meter and scanning electron microscopy(SEM) is reported. A study of the mechanical strength of the silicone rubber composite having various silicone fluids and fluid contents is also reported. It has been found that the kind of silicone fluid affects the diffusion rate of the silicone fluid from the bulk to the surface of the silicone rubber composite after artificial pollution.

• KIEE International Transactions on Electrophysics and Applications
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• 제5C권1호
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• pp.1-7
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• 2005

This paper describes the lightning surge analysis model of extra high voltage GIS using EMTP. Various lightning current parameters were investigated in order to confirm the impact on the lightning surge analysis such as lightning current amplitude, waveform, size of GIS, tower footing resistance and surge arresters. The multi-story tower model and EMTP/TACS model were introduced for the simulation of dynamic arc characteristics. The margin between the maximum overvoltage and BIL of the GIS was about 10 percent and the margin between the maximum overvoltage and BIL of the transformer was 21 percent.

• Proceedings of the KIEE Conference
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1376-1378
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• 1997

Mechanical and electrical properties of mica/epoxy composite materials were investigated by dynamic mechanical analyzer(DMA) and dielectric analysis (DMA). Both modulus and permittivity of sound specimens were higher than those of aged specimens. Two results show that $tan{\delta}$ of sound specimens is lower than that of aged specimens. DMA results showed that glass transition temperatures of sound and aged specimens are observed to be $87.16^{\circ}C$ and $88.38^{\circ}C$, which increases with the increase of aging time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.544-547
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• 1999

To develop the better insulants. the zeolite particle, which is aluminosilicate mineral, was filled In the DGEBA/MDA/SN epoxy resin system. Dynamic DSC curves of cured specimens with various contents of zeolite were observed and the glass transition temperature(T$_{g}$) was obtained. According to this result, we could carry out the experiment concerned with the dielectric breakdown strength around T$_{g}$ and find the limit temperature for the application of the DDEBA/MDA/SN system filled with natural zeolite. T$_{g}$ increased with the content of zeolite. As the temperature increased, the dielectric breakdown strength decreased rapidly, in the region of T$_{g}$. At the high temperature, the deterioration by electrical stress was activated. The diameter of puncture at the high temperature was larger 7han that at the room temperature.erature.

• Transactions on Electrical and Electronic Materials
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• 제16권3호
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• pp.107-111
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• 2015

Our work is based on the development of a numerical model to develop a methodology for predicting the aging and breakdown in insulation due to the dynamics of space charge packets. The model of bipolar charge transports is proposed to simulate space charge dynamic for high DC voltage in law-density polyethylene (LDPE), taking into account the trapping and detrapping of recombination phenomena, this model has been developed and experimentally validation. Theoretical formulation of the physical problem is based on the Poisson, the continuity and the transport equations as well as on the appropriate models for injection. Numerical results provide temporal and local distributions of the electric field, the space charge density for the different kinds of charges, conduction and displacement current densities, and the external current.

• The Transactions of the Korean Institute of Electrical Engineers C
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• 제52권1호
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• pp.25-34
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• 2003

Gas insulated switchgear(GIS) is an important equipment in a substation. It is highly desirable to measure a partial discharge(PD) in GIS which is a symptom before insulation breakdown occurs. The issue is that the PD signal is weak and sensitive to external noise. In this paper, the algorithm for detection of PD in GIS using wavelet transform is proposed. The wavelet transform provides a direct quantitative measure of spectral content, "dynamic spectrum", in the time-frequency domain. The recommended mother wavelet is 'Daubechies' wavelet. 'db4', the most commonly applied mother wavelet in the power quality analysis, can be used most properly in disturbance phenomena which occurs rapidly for a short time. Through the procedure of wavelet transform, noise extraction and reconstruction, the signal is Analyzed to determine the magnitude of PD in GIS. In experimental results, we can know that partial discharge is exactly detected in combination of Dl and D2 using wavelet transform.transform.

• Proceedings of the KIEE Conference
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.156-158
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• 1994

In recent days, the various adjustable speed drives are widely employed at the industrial applications for the purpose of energy saving and speed control. In particular, for the machine control applications. the switching frequency is required to be increased for better dynamic performance of the drive. Moreover, this also leads to the reduction of the switching loss of the device. For IGBT (Insulated Gate Bipolar Transistor), the most widely used switching device in the inverters below the 100[kW] range, the falling and falling time is of the order about $200{\sim}300[ns]$. Therefore unexpected phenomena occurs such as voltage spikes due to high gradient of current at the switching instant, the weakening of motor insulation due to high gradient of voltage. In this paper, a new voltage gradient suppression technique is presented in both theoretically and experimentally.

• Journal of the Earthquake Engineering Society of Korea
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• 제10권5호
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• pp.49-61
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• 2006

The floor impact sound insulations are installed frequently for reducing the floor impact sound into the floor slab of the residential buildings in recent years. Therefore the analytical FE model considering the insulation is needed for the sound and vibration analysis of the floor and it is necessary to use a refined finite element model fer considering the large number of modes involved dynamic responses. So it is very difficult to use FE model because of the tiresome task for constructing the FE model, taking a lot of times for analysis and the impossibility of using the proportional damping. The efficient analysis and modeling method are proposed to the dynamic analysis for the floor with damping layer in this study. The floor slabs and finished layers are modeled individually and the spring elements that mean damping layers used to connect two parts. The dynamic analysis by the $Newmark-{\beta}$ method is performed to solve the non-proportional damping problem due to the damping coefficient of insulations.