• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.173-178
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• 2001

The classical queuing analysis has been tremendously useful in doing capacity planning and performance prediction. However, in many real-world cases. it has found that the predicted results form a queuing analysis differ substantially from the actual observed performance. Specially, in recent years, a number of studies have demonstrated that for some environments, the traffic pattern is self-similar rather than Poisson. In this paper, we study these self-similar traffic characteristics and the definition of self-similar stochastic processes. Then, we consider the examples of self-similar data traffic, which is reported from recent measurement studies. Finally, we wish you that it makes out about the characteristics of actual data traffic more easily.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.123-126
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• 2003

This paper proposes a speed-sensorless induction motor control system using the rotor flux error. The rotor flux observer uses the reduced- dimensional state estimator technique instead of directly measuring the rotor flux. The estimated rotor speed is obtained directly from the electrical frequency, the slip frequency, and the rotor speed compensation with the estimated q-axis rotor flux. To precisely estimate the rotor flux, the actual value of the stator resistance, whose actual variation is reflected, is derived. For fast calculation and improved performance of the proposed algorithm, all control functions are implemented in software using a digital signal processor (DSP) with its environmental circuits. Also, it is shown through experimental results that the proposed system gives good performance for the speed-sensorless induction motor control.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.173-174
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• 2006

High power amplifier (HPA), which is used in transmitter of wireless communication systems, usually works in near saturation point in order to achieve maximum efficiency. In this region, HPA can introduce undesirable nonlinear effects. In this paper, we present a polynomial modeling method for efficient techniques to compensate for nonlinear distortion introduced by nonlinear HPA. Proposed polynomial predistorter inverses actual amplifier. Namely, we derive polynomials of amplifiers from analytical method and the electrical parameters in the data sheet of an actual amplifier and then can derive polynomial predistorter by inversing them. It is an effective and a simple method to compensate nonlinear distortion. SSPA(Solid-state power amplifier) is considered. We also analyze the effects of predistortion on the SER performance of communication system with 16-QAM modulation format. The results have shown the efficiency of this model.

• Journal of Ocean Engineering and Technology
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• v.22 no.3
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• pp.58-63
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• 2008

A 32-ft class leisure boat was newly developed using statistical analysis of actual ships. Resistance performances were investigated by testing models in a high-speed circulating water channel, and with the CFD method. The effects of a trim tab and of a fin attached at the hull side were studied together. Wave patterns were observed to clarify the relationship between resistance performance and wave characteristics. It was found that a trim tab and a side fin play a role in increasing resistance performance within a certain velocity range.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.454-459
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• 2001

The classical queuing analysis has been tremendously useful in doing capacity planning and performance prediction. However, in many real-world cases. it has found that the predicted results form a queuing analysis differ substantially from the actual observed performance. Specially, in recent years, a number of studies have demonstrated that for some environments, the traffic pattern is self-similar rather than Poisson. In this paper, we study these self-similar traffic characteristics and the definition of self-similar stochastic processes. Then, we consider the examples of self-similar data traffic, which is reported from recent measurement studies. Finally, we wish you that it makes out about the characteristics of actual data traffic more easily.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.468-471
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• 2001

The classical queuing analysis has been tremendously useful in doing capacity planning and performance prediction. However, in many real-world cases. it has found that the predicted results form a queuing analysis differ substantially from the actual observed performance. Specially, in recent years, a number of studies have demonstrated that for some environments, the traffic pattern is self-similar rather than Poisson. In this paper, we study these self-similar traffic characteristics and the definition of self-similar stochastic processes. Then, we consider the examples of self-similar data traffic, which is reported from recent measurement studies. Finally, we wish you that it makes out about the characteristics of actual data traffic more easily.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.3
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• pp.223-230
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• 2017

A low-cost BLDC motor with hall sensor is used to drive the position control of a facility security monitoring system in this paper. Low measurable frequency of the hall sensor signal in low-speed regions results in difficulty in obtaining accurate speed detection and position control. To improve system control performance, we propose a variable gain of position controller and stop mode control scheme according to the motor speed and error position with pre-set deceleration time. The proposed stop mode control scheme is activated around the stop position to forcibly move the BLDC motor to the stop position in low speed. In the proposed stop mode, the motor current is controlled by the actual speed with the reference rotating angle. The control performance of the proposed position control is verified through experiments at the actual rail guided facility security monitoring system.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.30 no.2
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• pp.7-13
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• 2022

As the demand for simulated flight training and interest in new technology training increase, this study analyzed the performance of flight simulator training and actual flight training subjects to confirm efficient flight simulator training curriculum. Summarizing the results of the study, found that flight simulator training had a significant positive effect on the actual flight training performance and in particular had a relatively large effect on the air maneuver, traffic pattern, cross country flight subjects. As a result of analyzing theoretical major classes that affect flight simulator training to verify the correlation, found that principle of air navigation, air traffic service, and helicopter flight theory were affected in order. The significance of this study was to identify the curriculum and ground lesson that should be focused on effectively performing flight simulator training in the helicopter private pilot course.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.115-116
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• 2020

Due to the nature of modern society, buildings are becoming larger and more complex. As a result, the design conditions of the building are changing. However, despite the complexities of buildings, the fire resistance performance is still equalized to one hour without considering fire engineering analysis in Korea, so there is a risk according to actual fire design conditions. Therefore, the purpose of this study is to calculate the required fire resistance time for actual fire through fire mechanics analysis and case study.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1341-1346
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• 2008

This paper presents the heating performance of a water-to-refrigerant type ground source heat pump system (GSHP) installed in a school building. The evaluation of the heating performance has been conducted under the actual operating conditions of GSHP system in the winter. Ten units with the capacity of 10 HP each were installed in the building. Also, a closed vertical typed-ground heat exchanger with 24 boreholes of 175 m in depth was constructed for the GSHP system. For analyzing the heating performance of the GSHP system, we monitored various operating conditions, including the outdoor temperature, the ground temperature, and the water temperature of inlet and outlet of the ground heat exchanger. Simultaneously, the heating capacity and the input power were evaluated for determining the heating performance of the GSHP system. The average heating coefficient of performance (COP) of the heat pump was found to be 5.1 at partial load of 46.9%, while the overall system COP was found to be 4.2.