• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.68 no.1
• /
• pp.61-68
• /
• 2019

Only the power is converted from AC to DC, in accordance with IEC 60587 based test method, in order to develop the LSR(Liquid Silicone Rubber) insulator material for HVDC, the experiment of Inclined Plate Tracking and Erosion Resistance was conducted. A contaminant (2.5 mS/cm: ammonium chloride) was applied at a rate of 0.3 ml/min and a voltage of ${\pm}3.5kV$, and was evaluated on the basis of 60 mA/2s. The samples were prepared by dispersing LSR/Nano silica_25wt% Composites in LSR. The erosion phenomena of surface discharge and tracking due to DC polarity and negative polarity were measured by image, leakage current maximum and thermal camera. The thermal imaging camera measured the surface temperature generated by the joule heat of the leakage current due to the drying discharge and the conductive current. After the measurement, the tracking and erosion mechanisms were evaluated for erosion weight, erosion depth and erosion length. Positive and negative polarity of LSR/Nano Silica_25wt% composite Tracking and erosion results show that positive polarity is more severe than negative polarity.

• Journal of applied mathematics & informatics
• /
• v.31 no.1_2
• /
• pp.111-118
• /
• 2013

External excitations are employed to investigate properties of optical media, with measurement data often analyzed via linear response theory. In this respect, external forcing is modeled here by well-known Poisson and negative-binomial distributions. Ensuing dynamics is examined with a special attention to the relative decay rates of damped harmonic oscillators to such external forcing, along with its relationship to other physical phenomena.

• Proceedings of the Korean Society of Computational and Applied Mathematics Conference
• /
• 2003.09a
• /
• pp.13.1-13
• /
• 2003

The Markovian arrival process with marked transitions (MMAP) is useful in modeling input processes of stochastic system with several types. Especially, the MMAP can be used to model the phenomena where the correlation of different types is considered. In this talk we discuss modeling issues for the queue with three types of customers; ordinary customers, negative customers and disasters which are correlated by using MMAP. We also present the recent results and further studies.

• Proceedings of the KIEE Conference
• /
• 1998.07d
• /
• pp.1436-1437
• /
• 1998

In this paper, the result of experimental investigation into the streaming electrification phenomena of insulating oil under an external dc field effect is described. Energization by positive dc voltage enhanced the streaming electrification. but when the applied voltage was negative, the polarity of streaming current was field strength dependent.

• Proceedings of the IEEK Conference
• /
• 2000.06e
• /
• pp.73-76
• /
• 2000

We study the Chua oscillator circuit by considering a negative resistor as a characteristic parameter which controlled by the CdS(Cadmium Sulphide) cell. This is a new way to observe several chaotic phenomena with the same initial condition continuously. Since we can control the internal resistance of the CdS cell by an additional circuit, our autonomous chaotic oscillator circuit makes it possible to measure the voltage value continuously and automatically.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.34 no.9
• /
• pp.349-354
• /
• 1985

The conducting currents of polypropylene film was measured a function with electric fields at temperature of 25,35,45( C). It appears that there are four regions of conducting currents, depending upon the strength of the applied electric field` ohmic region based on ionic conduction, Poole-Frenkel region, Schottky region and negative resistance region. Several information of dielectric constant and potential barrier height were obtained.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.5 no.2
• /
• pp.35-44
• /
• 1999

High negative pressure coefficient is formed in the corner of the bluff body structures. For many curtain wall designers this phenomena is of interest because this high negative pressure coefficient is adopted in structural calculation. The present study is aimed to investigate shedding vortex characteristics of two-dimensional rectangular prism flow. Unsteady calculation by finite difference method based upon SOLA is carried out for three aspect ratios(1:1, 1:2, 1:3) of Re=10$^4$ in viscous incompressible flow within infinite domain. Fluctuation of velocity components at various pick-up points and time variation of drag and lift coefficients are analysed by FFT method to reveal shedding vortex frequency patterns. At aspect ratio 1:1, one primary Strouhal number appears for about all pick-up points. At aspect ratio 1:2, two representative Strouhal numbers are classified by pick-up positions and their flows show two different reattachment patterns. For aspect ratio 1:3, frequency spectrum maintains multiple peaks.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2007.05a
• /
• pp.271-273
• /
• 2007

This paper presents the experimental results of underwater discharges in 25 mm point-plane gap caused by impulse voltage. Discharge phenomena were observed by digital cameras and recorded by oscilloscope. As a result, discharge patterns in positive and negative polarity have different shapes according to applied voltage amplitudes. The positive discharge is like root but the negative discharge is similar to bush. As the voltage is increased, the discharge routs are thick and have more branches. Also the time to breakdown is inversely proportional to voltage.

• Journal of the Korean Ceramic Society
• /
• v.27 no.3
• /
• pp.337-344
• /
• 1990

As a function of sintering temperature and time, the electrical properties of ruthenium based thick film resistors were investigated with microstructure. The variatio of resistivity and TCR(temperature coefficient of resistance)trends of sintered speciman at various sintering temperature were different low resistivity paste(Du Pont 1721) from high one(Du Pont 1741). These phenomena are deeply relative to microstructure of sintered film. With increasing the sintering temperature for 1721 system, the electrical sheet resistivity decreased, but again gradually increased above 80$0^{\circ}C$. And TCR trends in 1721 system are all positive. On the other hand the electrical sheet resistivity of 1741 resistor system decreased with sintering temperature. And TCR trends variable according to sintering temperature. TCR of speciman sintered at $700^{\circ}C$ was negative value, and TCR of 80$0^{\circ}C$ sintered speciman coexisted negative and positive value. But in case of speciman sintered at 90$0^{\circ}C$, TCR was positive value. As results of this fact, it was well known that the charge carrier contributied to electrical conduction in 1741 resistor system varied with sintering temperature.

• Journal of Korean Academy of Nursing
• /
• v.23 no.2
• /
• pp.224-244
• /
• 1993

This study was designed to develop and test a model of the theoretical structure of factors influencing womens’ attitudes toward menstruation, specifically, premenstrual discomfort or pain, negative affect, disability and role acceptance. The conceptual framework was built through a review of the literature. For the purpose of testing the model, data were collected from April to June, 1992 with the use of Menstrual Distress Questionnaire, Menstrual Attitude Questionnaire, Sex Role Acceptance Scale. Data analysis was done with the SPSS PC/sup +/ for descriptive statistics and PC-LXSREL 7.13 for covariance structure. The study subjects consisted of 320 women college students in 2 three-year nursing junior colleges and 1 department of nursing of a college of medicine. The mean age of the subjects was 19, the mean age at monarch was 13.7, the mean menstrual cycle was 29.7 days and the mean menstrual duration was 5.3 days. The amount of menstrual discharge was moderate and the menstrual cycle variability was within 3 days. The score for pain, negative affect and disability were higher during the perimenstrual period than intermenstrual period. The fit of the hypothetical model with the six paths and the empirical data was high [X²(df=4)=. 57 (P=.966), GFI =.999, AGFI =.997, RMR=.008]. The hypotheses were supported on acceptable level of significance. 1) The higher the pain and negative affect, the stronger the disability. 2) The higher the pain, negative affect and disability, the more negative the attitudes toward menstruation. 3) The lower the women's role acceptance, the more negative the attitudes toward menstruation. The model was supported by the empirical data, and thus these results may help nurses and nursing scientists to understand and support these phenomena of womens’ health experience.