• Journal of the Semiconductor & Display Technology
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• v.9 no.1
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• pp.67-71
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• 2010

Head up display’s cooling system is auto-diagnosed resulting from the external environment. The quantity of heat depending on this Head up display’s cooling system layout determines the speed of FAN for system cooling. In other words, a system’s heat quantity is planned through the air density depending on altitude, the amount of wind in air depending on FAN control condition, and the algorithm that is proportional to delta temperature. To detect the altitude, we use the criteria of delta T, which is determined by the subtracted value of LED junction temperature, and atmospheric temperature that is recorded on the Head up display system. Depending on the classification of delta T value, the altitude section is determined. While we can use GPS as the tool to detect the altitude, we should predict the change of the air density as the altitude alters, and should not just measure the altitude. And the value of delta T is used as the criterion of detecting the altitude for increasing the cooling efficiency of the car’s inner Head up display system with reflecting the speed of the FAN dependent upon the air density. In our theory, altitude is depending on the value of delta T and stabilizing or maintaining the system’s temperature by changing FAN’s rpm depending on determined value of altitude.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.6
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• pp.284-292
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• 2005

Because all of the short-circuit testing laboratories have the limitation of test facilities, the synthetic making test methods have been used to estimate the short-circuit making performance of the ultra high-voltage circuit breaker as the alternative to direct test methods. So, KERI(Korea Eelctrotechnology Research institute) has completed the construction of the synthetic making test facilities using the low capacity step-up transformer method which fulfill the requirements specified in newly revised IEC 62271-100 Edition 1.1(2003) and have the testing capability up to 550kV, 63kA full-pole circuit breaker. The test facilities using the low capacity step-up transformer method presented in this paper are made up of the unit equipments such as HCS(High-speed Closing Switch), ITMC(Initial Transient Making Current) circuit and UP TR(low capacity step-up transformer) and have the operating range of 17.6$^{\circ}$ $\~$ 145.1$^{\circ}$ for testing the circuit breaker rated on up to 50kA and 43.1$^{\circ}$ $\~$ 119.6$^{\circ}$ for more than 50kA.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1249-1253
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• 2009

Enhancements of transport capacity in Gyeongbu line are continuous with the operating cost reduction and Korean economic development. Besides, requirements of a people about speed-up and customer service after the opening of high-speed railway(KTX) are being increased nowadays. Therefore, development and effort for speed increase of high-speed railway(KTX) have to be encouraged and supported by the government. In this study, market and technology trends for speed increase of high-speed train in Korea and abroad were investigated. As a result, we suggested to improve the railway infra for speed increase of high-speed train in Gyeongbu line.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.565-568
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• 2005

This paper presents dynamic characteristics of super high speed SRM and it's drive. The nonlinear model of super high speed SRM is implement by Matlab/simulink and the simulation results show that the prototypeSRM can operate up 20,000[rpm]with stable performance.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1138-1140
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• 2005

This paper presents dynamic characteristics of super high speed SRM and it's drive. The nonlinear model of super high speed SRM is implement by Matlab/simulink and the simulation results show that the prototypeSRM can operate up 20,000[rpm]with stable performance.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.232-239
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• 2013

This paper proposes an improved stator flux estimator through ensuring conventional PLPF to act as a pure integrator for sensorless control of induction motors. Conventional PLPF uses the estimated synchronous speed as a cut-off frequency and has the gain and phase compensators. The gain and phase compensators are determined on the assumption that the estimated synchronous angular speed is coincident with the real speed. Therefore, if the synchronous angular speed is not same as the real speed, the gain and phase compensation will not be appropriate. To overcome the problem of conventional PLPF, this paper analyzes the relationship between the synchronous speed error and the phase lag error of the stator flux. Based on the analysis, this paper proposes the synchronous speed error compensation scheme. To achieve a start-up without speed sensor, the current model is used as the stator flux estimator at the standstill. When the motor starts up, the current model should be switched into the voltage model. So a stable transition between the voltage model and the current model is required. This paper proposes the simple transition method which determines the initial values of the voltage model and the current model at the transition moment. The validity of the proposed schemes is proved through the simulation results and the experimental results.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1540-1551
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• 2015

The detection of position and speed in BLDC motors without using position sensors has meant many efforts for the last decades. The aim of this paper is to develop a sensorless technique for detecting the position and speed of BLDC motors, and to overcome the drawbacks of position sensor-based methods by improving the performance of traditional approaches oriented to motor phase voltage sensing. The position and speed information is obtained by computing the derivative of the terminal phase voltages regarding to a virtual neutral point. For starting-up the motor and implementing the algorithms of the detection technique, a FPGA board with a real-time processor is used. Also, a versatile hardware has been developed for driving BLDC motors through pulse width modulation (PWM) signals. Delta and wye winding motors have been considered for evaluating the performance of the designed hardware and software, and tests with and without load are performed. Experimental results for validating the detection technique were attained in the range 5-1500 rpm and 5-150 rpm under no-load and full-load conditions, respectively. Specifically, speed and position square errors lower than 3 rpm and between 10º-30º were obtained without load. In addition, the speed and position errors after full-load tests were around 1 rpm and between 10º-15º, respectively. These results provide the evidence that the developed technique allows to detect the position and speed of BLDC motors with low accuracy errors at starting-up and over a wide speed range, and reduce the influence of noise in position sensing, which suggest that it can be satisfactorily used as a reliable alternative to position sensors in precision applications.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.3
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• pp.467-473
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• 2018

R-Bar(Overhead Rigid Conductor system) is being developed for the high-speed in Europe because it has an advantage of cross section area reduction of tunnel compared with OCS (Overhead Catenary Line). Because there are lots of underground sections and mountains in korea, it is necessary to develop the R-Bar for a high-speed line. In this study, a method on speed-up of transition section between OCS and R-Bar is proposed. The commercial program, DAFUL, is used to predict a dynamic characteristics between Overhead Line and pantograph. The program is evaluated according to EN 50318 which is the European Norm for evaluation of the program. Using the evaluated modeling and method, a method for the max. speed of 250 km/h of transition section is proposed.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.89-94
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• 2006

The tire delivering power generated from engine to the ground pulls a vehicle to move. Radius of tires is changeable due to elasticity that depends on the speed of vehicle and traction force. The main objectives on this study are real time measurement of dynamic radius and slip ratio according to the speed and traction force. The dynamic radius is proportional to speed and traction force. According to measurement, the dynamic radius is increased about 3mm under 100km/h compared to stop. It is also increased about 1.5mm when a traction force is supplied as much as 4kN compared to no load state at low speed. There is no strong relationship between slip ratio and vehicle speed. The slip ratio is measured up to 4% under WOT at first stage gear. Through this research, the method of measuring dynamic radius and slip ratio is set up and is expected to be applied to the measurement of traction force in chassis dynamometer or accelerating and climbing ability.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.747-750
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• 2006

A turnout which permits trains to pass from one track to another has a disconnecting rail component, namely a crossing, so that noise and vibration arc occurred abruptly when train is passing through it. In Korea, it is planned to adopt the high speed tilting train, which operates at the speed of 180 km/h, at the conventional line. However, for application of the tilting train, it is prerequisite to establish the stable turnout system allowing the tilting train to pass through it without reducing speed. This study was performed to evaluate noise and vibration emitted from the prototype turnout which is developed for speed-up of the conventional line. For the purpose, noise and vibration were measured at near the conventional turnout and the improved one, which is constructed at Waegwan station and Kumi station of Gyeongbu line, respectively.