• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.12
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• pp.1128-1133
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• 2006

The most important thing to secure safety and reliability of railway vehicles is to verify performance characteristics of equipments, and related companies or research institutes had many efforts to verify performances and functions of equipments synthetically and efficiently. KHST(Korean High Speed Train) has been developed by KRRI (Korea Railroad Research Institute). An electric railway system is composed of high-tech subsystems, among which main electric equipment such as transformers and converter are critical components determining the performance of rolling stock. We developed a measurement system for on-line test and evaluation of performances of KHST. The measurement system is composed of software part and hardware part. Perfect interface between multi-users is possible. A new method to measure temperature was applied to the ]measurement system. By using the system, fault diagnosis and performance evaluation of electric equipment in Korean High Speed Train was conducted during test running.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.1990-1992
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• 1998

A vector control scheme is widely used in AC drive system in these days. In this country for commercializing the system, it has lots of dependency on advanced foreign technology. Therefore we have developed high-performance vector controlled inverter sytems ourselves for two years whose capacitives are 15kW, 30kW and 45kW. For computation of data in high speed DSP is empolyed and by using a IGBT with high switching the current ripple is reduced. Consequently, developed drive systems have high performance and accurary on speed control. There are proved in experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.1-7
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• 2004

It is necessary for starting voltage to him on high pressure discharge lamp. This starting voltage supply to high pressure sodium vapor lamp as electric discharge lamp, Electric field is producted in Electric discharge tube, So accelerative electron collide against vapour atom and second electron is generated, And rapidly the current flow to Electric discharge tube. This paper showed that the life cycle and exchanges time for all electric discharge lamp was different according to each manufactures, This paper is proposed the evaluating algorithm of exchanges time for high pressure sodium vapor lamp, used LabVIEW software package.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.137-143
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• 2006

The effect of electric fields on flame speed has been investigated experimentally by observing propagating premixed flames in a tube for methane/air mixtures. The flame speeds were measured in both the normal and micro gravity conditions to substantiate the measurements. The results show that the flame speeds were enhanced by both the AC and DC electric fields, as the flame approached to the high voltage electrode located on the one end of the tube. The enhancement of flame speed was proportional to the square root of the electric field intensity, defined as the voltage applied divided by the distance of flame from the high voltage electrode, when the electric field intensity is sufficiently large. When the electric field intensity was low, there existed critical intensities, below which the electric fields did not influence the flame speed. This critical electric field intensity correlated well with the flame speed.

• Journal of Aerospace System Engineering
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• v.15 no.4
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• pp.21-29
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• 2021

As global environmental regulations have been strengthened, the eco-friendly market has grown rapidly. In the field of aircraft, research on electric vertical take-off and landing aircraft that can enter city centers and perform personal air transportation using electric propulsion is ongoing. For aircraft using electric propulsion methods to operate reliably, electric power thrust systems are a key factor. Electric aircraft require a high power density for propulsion systems with strict limits on volume and weight. The efficient control of inverter systems is essential for achieving high power density. Therefore, in this paper, the characteristics of inverters and motors were analyzed through simulations based on the space vector pulse width modulation (PWM) and discontinuous PWM methods for controlling inverter systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.234-234
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• 2009

This paper illustrates the use of electric field computation to optimize the design of high voltage composite bushing. In the bushing, a high electric stress occurred between field shaper and central conductor by the closely space. Also coaxial cylindrical shield has a great height along the axis to control an electric field. Consequently, all the potentials are raised axially along the field shaper and electric stress is concentrated on a part of the surface of the FRP tube near the upper end of the field shaper. Maxwell 2D simulator based on the boundary element method was also introduced in order to verify the reliability of the polymer bushing. The optimized design uses internal elements for electric stress grading at critical parts of the bushing.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.9-11
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• 2003

Image sticking, the phenomenon that the previously displayed pattern still remains after the image is changed into different image, is one of the most serious problem in realizing high picture quality. There are various methods decreasing the image sticking phenomenon. In this paper, we have tried to decrease boundary image sticking by reducing the discharge concentration phenomenon in the boundary of pattern using the new driving method that is applied to bias in the address electrode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.35-35
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• 2010

This paper illustrates the use of electric field computation to optimize the design of high voltage composite bushing. In the bushing, a high electric stress occurred between field shaper and central conductor by the closely space. Also coaxial cylindrical shield has a great height along the axis to control an electric field. Consequently, all the potentials are raised axially along the field shaper and electric stress is concentrated on a part of the surface of the FRP tube near the upper end of the field shaper. Maxwell 2D simulator based on the boundary element method was also introduced in order to verify the reliability of the polymer bushing. The optimized design uses internal elements for electric stress grading at critical parts of the bushing.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1284-1285
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• 2006

We reported a P/M soft magnetic material with core loss value of $W_{10/1k}=68W/kg$, which is lower than that of 0.35mm-thick laminated material, by using high purity gas-atomized iron powder. Lack of mechanical strength and high cost of powder production are significant issues for industrial use. In order to achieve both low core loss and high strength by using inexpencive powder, the improvement of powder shape and surface morphology and binder strength was conducted. As the result, the material based on water-atomized powder with 80 MPa of TRS and 108 W/kg of core loss (W10/1k) was achieved.

• Journal of the Korean Professional Engineers Association
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• v.26 no.4
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• pp.65-72
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• 1993