• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.175-180
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• 1998

This paper describes evaluation of oxidation stability for diesel engine oils by Hot-tube oxidation tester at high temperature. Evaluation was rated by visual inspection of lacquer in capillary glass tube and TAN determination of used oil. Air, NO$_2$-air and SO$_2$-air mixed gases were used as oxidizing gas. One oil which has low oxidation stability is selected and reformulated by addition of some additives such as antioxidant, detergent and disperant to improve oxidation stability. As a results of reformulation, antioxidant and detergent was effective for improvement of high temperture oxidation stability on diesel engine oil.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.28B no.5
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• pp.421-430
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• 1991

This paper investigated the errect of the right-half-plane zero on stability in the buck-boost DC-DC converter which is one type of the switching regulator and the stability region for the variation of the output current is obtained by evaluating the feedback gain. And it is clarified that the damping ratio decreases gradually by increase of the feedback loop gain and the regulation system of the converter becomes unstable, and from the transient response analysis we obtainedthe stability region about this converter. From above result it is known that the stability decreases by the existence of the right-half-plane zero. For the improvement of stability, we carried out one pole compensation in feedback circuit and obtained the avaliable stability region in relation to the gain bandwidth product from the stability and transient response analysis. These results were established experiment.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.392-398
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• 2000

When soft ground improvement is proceeded in costal area using compulsory replacement method, it is very important that the method of stability of embankment above replacement layer can be obtained if non-replaced soft layer is remained, and there are a lot of influence factors which affect the stability of embankment, such as replacement depth, the water content of dredged soil and the width of replacement layer, etc. If soft layer was replaced completely by good quality materials, there would be no problems about stability of embankment, but practically non-replaced layer would be remained as the strength of soft layer will be increased. So another consideration is required to get the stability of embankment. In this study, stability of embankment among these factors was compared, and from that results, the better way that could obtain the stability was presented.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.208-211
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• 2001

This paper proposes a novel flyback topology and its control scheme, where some disadvantages of the conventional one are eliminated while the circuit simplicity is maintained, and furthermore confirms the improvement of its dynamic response and stability analytically and experimentally.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.463-467
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• 1991

A continuous variable structure system control as a DC servomotor trackhig controller is proposed for the improvement of the chattering problems. The stability property of the proposed algorithms is analyzed. The prescribed trackfiig error is gauranteed in the existence of load variations based on the stability analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.537-538
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• 2010

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.3
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• pp.241-247
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• 2011

Marine casualties of vessel are said to be in most case caused by human error, but it would be valid for the assumption that the ship is built with high quality and then should be acceptable to the safety standards. It means that the inherent characteristics of a ship should be the first consideration on the safety of ship. Therefore it is basically necessary for navigator to grasp the inherent stability of his ship and ensure that the ship complies with the minimum statutory standards of stability. This study is to realize the stability of the Korean offshore large purseiner varying with loading conditions by the inclining data and some calculations. The author compared the stability of the ship with IMO criteria and domestic rule, and proposed some improvement for the safety of the ship. The results are summarized as follows ; The values of GM of the ship according to the loading condition in navigation satisfy both of the IMO criteria and the domestic rule, but in case of the area under the GZ curves between the heel angles of $30^{\circ}$ and $40^{\circ}$, and the heel angle occuring the maximum righting lever not satisfy the IMO rule at the fishing ground departure and arrival conditions in the haul in net situation. The initial metacentric height of the ship is very large, but the range of stability and the occurring angle of the maximum GZ are very small, so even small inclining can bring about the beam end. The best method of improvement for that is to increase the freeboard of the model among the variables.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.9
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• pp.843-850
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• 2007

This paper proposes a somatosensory stimulation system for the improvement of postural stability using vibration as somatosensory stimulation. This system consists of vibratory stimulation and postural response measurement. To evaluate this system, the center of pressure(COP) was closely observed in turn with simultaneous or separate mechanical vibratory stimulations to flexor ankle muscles (tibialis anterior, triceps surae) and two plantar zones on both feet while standing on a stable and an unstable support. The simultaneous vibratory stimulations cleared influenced postural stability and the effects of vibrations were higher with the unstable support. In separate vibratory stimulations, the extent of the COP sway reduced when the direction of the vibratory stimulations and that of the inclination of body coincided for flexor ankle muscle stimulations. In the contrary, the extent of the COP sway increased when the direction of the stimulations and that of body inclination coincided for plantar zone stimulations. These results can be useful for the development of rehabilitation systems that utilizes somatosensory inputs for postural balance.

• Journal of Powder Materials
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• v.24 no.5
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• pp.395-399
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• 2017

Solder paste is widely used as a conductive adhesive in the electronics industry. In this paper, nano and microsized mixed lead-free solder powder (Sn-Ag-Cu) is used to manufacture solder paste. The purpose of this paper is to improve the storage stability using different types of solvents that are used in fabricating the solder paste. If a solvent of sole acetate is used, the nano sized solder powder and organic acid react and form a Sn-Ag-Cu malonate. These formed malonates create fatty acid soaps. The fatty acid soaps absorb the solvents and while the viscosity of the solder paste rises, the storage stability and reliability decrease. When ethylene glycol, a dihydric alcohol, is used the fatty acid soaps and ethylene glycol react, preventing the further creation of the fatty acid soaps. The prevention of gelation results in an improvement in the solder paste storage ability.

• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.34-39
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• 2017

Semiconductor is one of the most internationally competitive areas among domestic industries, the major concern of which is the stability of the wafer manufacturing processes. The first process for the manufacturing of the semiconductor wafers is the ingot growing. The vibrations are supposed to be the most important factors for the ingot quality. In order to maintain the ingot quality, the growers have the automatic shut-down equipments which are activated by vibrations, and are sensitive enough to react to the earthquakes generated in Japan. In this study, the structure of an ingot grower was analyzed through experiments and computer simulations, and further the effects of design alterations to suppress the vibrations have been investigated. The final result shows that the vibrations can be reduced substantially to improve the stability of the structure.