• Journal of the Korean Institute of Telematics and Electronics
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• 제25권3호
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• pp.262-268
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• 1988

In this paper conditions are derived, which ensure the existence of a quasi-sliding mode on the control switching hyperplane in discrete variable structure control systems and also remove the reaching phase problem observed in continuous-time variable structure systems. In addition, a discrete variable structure tracking controller which has adaptive properties is devised based on these results. This controller has useful properties, such as small sensitivity to the variation of plant parameters and to disturbances and its performing speed is fast compared to that of other adaptive controller.

• Proceedings of the Botanical Society of Korea Conference
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• 한국식물학회 2001년도 춘계학술발표대회:발표눈문요지록
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• pp.18-18
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• 2001

• Proceedings of the Korean Magnestics Society Conference
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• 한국자기학회 2003년도 하계학술연구발표회 및 한.일 공동심포지엄
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• pp.128-129
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• 2003

• Proceedings of the Korean Society of Potoscience Conference
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• 한국광과학회 1996년도 학술대회지
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• pp.39-39
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• 1996

• Proceedings of the Zoological Society Korea Conference
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• 한국동물학회 1994년도 한국생물과학협회 학술발표대회
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• pp.238.2-238
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• 1994

No Abstract, See Full Text

• The Journal of the Acoustical Society of Korea
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• 제21권3호
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• pp.213-220
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• 2002

The sound wave in the sea propagates under the effect of water depth, sound velocity structure, sea surface and bottom roughness, and bottom sediment distribution. In particular the sound velocity structure in shallow water varies with time and space, an? the sediment distributes very variedly with place. In order to investigate the seasonal variation of low-frequency sound propagation in the Yellow Sea, the propagation experiments were conducted along the same track in the middle part of the Yellow Sea at various seasons of spring. summer, and autumn. In this paper we consider the measurement results on the propagation loss with the sound velocity structure, and investigate the seasonal variation of the propagation loss. As a result, the propagation losses measured in summer were larger than the losses in spring and autumn. And the propagation losses measured in autumn were smaller than the losses in spring. The seasonal change of the propagation loss increased with the rise of sound frequency and the propagation range.

• Journal of the Korean Society for Precision Engineering
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• 제24권9호
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• pp.110-118
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• 2007

ISB (Inner structured and bonded) panel with a pyramidal inner structure is actively developing to reduce the weight and to improve the crashworthiness of the material. The objective of this paper is to investigate into the variation of impact characteristics of ISB panels with a pyramidal inner structure according to joining types between skin sheets and inner structures. Several drop impact tests have been performed. In order to examine the impact characteristics at a drawing condition, drawing type of experimental set-up has been proposed. From the results of the experiments, the influence of joining types between skin sheets and the inner structures on the characteristics of the deformation, the energy absorption and the failure has been quantitatively examined. In addition, it has been shown that maximum load decreased and the maximum displacement increases as the joining type changes from the bonding to the welding. The results of the observation of the specimen have been shown that major wrinkles form in the minor crimping direction irrespective of the joining types. Through the comparison of the experimental results for bonding and welding specimens, it has been shown that the absorption energy of the bonded specimen is nearly 1.3-1.5 times of the welded specimen at the same displacement.

• Journal of Ocean Engineering and Technology
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• 제17권5호
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• pp.39-47
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• 2003

A study of the structural strength evaluation on the doubler plate, considering various load cases that were subjected to in-plane and out of plane combined load, has been performed through the systematic evaluation process. In order to estimate the proper static strength of doubler plate for various load cases, elasto-plastic large deflection analysis is introduced, including the contact effect between main plate and doubler. The characteristics of stiffness and strength variation are discussed, based on the results. In order to compare the doubler structure with the original strength of main plate, without doubler, simple formulas for the evaluation of the equivalent flat plate thickness are derived for each load case, respectively, based on the additional series of analysis of flat plate structure. Using these derived equations, the thickness change of an equivalent flat plate is analyzed according to the variation of various design parameters of doubler platesome design guides are suggested in order to maintain the original strength of main plate without doubler reinforcement. Finally, correlation between derived equivalent flat plate formula and the developed buckling strength formulas are discovered, and these relations are formulated for the future development of simple strength evaluation formula of general doubler plate structure.

• Proceedings of the KIEE Conference
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.1225-1227
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• 1992

This paper presents a study on the variable structure PI(proportional and integrate) control which is insensible to the variation of parameters or external disturbance for driving DC motor. In the presented variable structure PI control (VSPIC), the sliding mode control was used at the below of 4000 rpm and PI control also used at the above of 4000 rpm with no load. In other way, the PI control was used at the below of 4000 rpm and the sliding mode control at the above of 4000 rpm with some loading, and then the output waveform following the variation of load was measured. intel 8031 microcomputer unit and IBM PC was combined to form the full system and the speed control was performed with it. The experimental result of the fast response to speed was more improve than it was open loop state. For load varing, the sliding mode insensible to external disturbance was applied and the improved response was obtained.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• 제15권1호
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• pp.91-96
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• 1997

In order to ensure the safety of a structure, it is essential to put in practice all sorts of measurement from the plan and execution to the management by stages. These measurements make it possible to verify a propriety of a plan and forecast an accident or a collapse caused by long lapse of time, making use of accumulated data. Close-Range Photogrammetry is a method to meet improvement and development of surveting technique. which offered data for maintenance and management of a structure. Dus to applying this way. reliance on measuring a variation of structure. Besides, data of variation will be utilized for maintenance and management of a structure.