• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.11
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• pp.625-631
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• 2003

The purpose of this paper is to assess experimentally system stability of the 154 ㎸ transmission system due to the current of the forthcoming AC High-Speed Railway (HSR) era. It introduces a simple method to evaluate the system stability The proposed method also shows the relationship between stability and power losses, and the stability indices made by the numerical process proposed in this paper will be used to assess whether a system can be stabilized or not. This paper also presents the improvement of the stability via loss reduction using STATCOM. Reactive power compensation is often the most effective way to improve both power transfer capability and system stability. The suitable modeling of the electric railway system should be applicable to the PSS/E. In the case study the proposed method is tested on a practical system of the Korea Electric Power Corporation (KEPCO) which will be expected to accommodate the heavy HSR load. Furthermore, it prove that the compensation of voltage drop and its by-product, loss reduction is closely related to improvement of system stability.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.87-92
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• 2000

In order to improve the instability of Plane journal bearing, it is introduced the leaf spring damper(LSD). The effects of dynamic characteristics of LSD on the stability of a plane journal bearing were investigated theoretically. The improvements on the stability of a plane journal bearing with LSD. are compared with the results of a floating ring journal bearing and of journal bearing without LSD. It found that a plane journal bearing with LSD will be an effective way in the improvement on the stability of rotor system.

• Tribology and Lubricants
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• v.17 no.3
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• pp.179-184
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• 2001

In order to improve the instability of plane journal bearing, it is introduced the leaf spring damper(LSD). The effects of dynamic characteristics of LSD on the stability of a plane Journal bearing were investigated theoretically. The improvements on the stability of a plane journal bearing with LSD are compared with the results of a floating ring journal bearing and of journal bearing without LSD. It found that a plane journal bearing with LSD will be an effective way in the improvement on the stability of rotor system.

• The Journal of the Acoustical Society of Korea
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• v.4 no.1
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• pp.16-21
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• 1985

Both shifiting the input signal's frequencies by a fixed frequency and compressing the input signal's bandwidth have been known to be effective in improving the stability margin of public adress systems operating in reverberant spaces. This paper describes the effect of an alternative approach of improving the acoustic-feedback stability and yet maintaining speech inteligibility by bandwidth compression and expansion. Conditions are derived for this technizue to be realized and an experimental system has been made - up. A series of experiments has been performed in small spaces and the results have shown that more than 5dB improvement can be obtained in the stability margin.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.166-173
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• 2005

A vehicle stability control logic for 4WD hybrid electric vehicle is proposed using the regenerative braking of the rear motor and electronic brake force distribution module. Performance of the stability control logic is evaluated for J-turn and single lane change. It is found from the simulation results that the regenerative braking at rear motor is able to provide improved stability compared with the vehicle performance without my stability control. Additional improvement can be achieved by applying the regenerative braking plus electronic brake farce distribution control. It is expected that the regenerative braking offers additional improvement of the fuel economy as well as the vehicle stability control.

• Tribology and Lubricants
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• v.11 no.2
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• pp.56-62
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• 1995

The anisotropic pressure distribution of the hydrodynamic bearing may generate the unstable vibration phenomenon over a certain speed. These vibrations, known as whirl, whip or rotor instability, cannot be sustained over a wide range of rotational spees. Besides these vibrations not only perturb the normal operation of a rotating machine, but may also cause serious damage to the machinery system. And, it is really impossible to change one parameter without changing others, or difficult to fabricate the modified non-circular type bearing, with all the other cures used just now, In this study, hybrid bearing with magnetic exciter is designed for stability improvement of hydrodynamic bearing rotor system without changing mechanical parameters. For stability study, eigenvalue study of the bearing-rotor system is executed by finite element method and results of analyses and experiments show the possibilities of the stability improvement of the hydrodynamic bearing system by using the electricmagnetic force.

• Journal of the Korean Wood Science and Technology
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• v.27 no.4
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• pp.30-37
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• 1999

The effects of heat treatment on the dimensional stability and bending properties of radiata pine sapwood were investigated. The dimensional stability was almost achieved by heat treatment though the loss of strength was accompanied as a negative effect. The improvement in dimensional stability of wood and the resultant reduction in bending properties were closely related to treatment temperature and duration. The optimum treatment conditions, which could be used to achieve a desired improvement in dimensional stability with resultant losses in modulus of rupture were proposed based on the results obtained in this study.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.207-210
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• 1995

In this paper, two representative schemes for vector control of induction motor without speed sensor are studied. First, the two sensorless systems which are implemented by voltage and current source are presented with new ideas and interpretations. Then a linear model around an operating point is proposed. Finally, the stability improvement of these systems are studied and evaluated by computing the trajectories of poles and zeros.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.170-180
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• 2008

Successful design, construction and maintenance of NATM tunnel demands prediction, control, stability guidelines, the estimation pre-improvement support system and monitoring of surface settlement, gradient and ground displacement with high accuracy. Moreover, urban NATM tunnel under difficult geotechnical conditions is important the estimation and necessary of pre-improvement support system. Various strategies have been proposed for the quantitative estimation of pre-improvement support system. This paper was investigated and analysed an assessment technique for the quantitative estimation of pre-improvement support system on underground space, as mountain and urban tunnel, in detail. The analysis performed on design and construction stage with field database using the proposed stability estimation index by many researcher including the critical strain and the apparent Young's modulus concept.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.11
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• pp.1149-1155
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• 2004

In this paper, novel methods for improvement of thermal stability of Ni-germano Silicide were proposed for nano CMOS applications. It was shown that there happened agglomeration and abnormal oxidation in case of Ni-germano Silicide using Ni only structure. Therefore, 4 kinds of tri-layer structure, such as, Ti/Ni/TiN, Ni/Ti/TiN, Co/Ni/TiN and Ni/Co/TiN were proposed utilizing Co and Ti interlayer to improve thermal stability of Ni-germano Silicide. Ti/Ni/TiN structure showed the best improvement of thermal stability and suppression of abnormal oxidation although all kinds of structures showed improvement of sheet resistance. That is, Ti/Ni/TiN structure showed only 11 ohm/sq. in spite of 600 $^{\circ}C$, 30 min post silicidation annealing while Ni-only structure show 42 ohm/sq. Therefore, Ti/Ni/TiN structure is highly promising for nano-scale CMOS technology.