• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.124-132
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• 2004

A hydraulic system is difficult to keep the performance due to non-linearity, load pressure which changes according to working condition and system parameter variation, the requirement of control algorithm has been risen in order to satisfy them. An adaptive control is a control method which is suggested to achieve a control object though plant characteristics change. In spite of the case that plant characteristics and the degree of variation are difficult to grasp, adaptive control can keep the characteristics of closed-loop system regularly. In this study GMVAC(generalized minimum variance adaptive control) combined with output error feedback is proposed in order to solve problems of non-minimum phase, vibration and overshoot in initial response of the plant. The control performance according to the variation of characteristics of the plant is evaluated by changing the supply pressure only.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.422-425
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• 1997

We consider the robust control problem for nonminimum phase(NMP) systems with parametric uncertainty which appear often in aircraft and missile control. First, a new method that makes such an uncertain NMP system to be factored as a interval minimum phase(MP) transfer function and a time delay term in the Pade approximation form has been presented. The controller to be proposed consists of a compensator $C_{Q}$(s) with Smith predictor in the internal model control(IMC) structure, so that it can have good robustness and performance against the structured uncertainty and the time delay behaviour due to NMP plant the $C_{Q}$(s) is designed on the MP model by using QFT. The stability and performance of overall system has been evaluated by the generalized Kharitonov theorem.rem.

• Journal of Chest Surgery
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• v.31 no.12
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• pp.1212-1216
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• 1998

Background: Recently thoracoscopic surgery is widely applied in thoracic surgical field and hyperhidrosis is one of the most frequently operated diseases. Material and Method: From June 1997 to February 1998, 30 patients with hyperhidrosis underwent bilateral thoracic sympathectomy under thoracoscopy at Inje University Sanggye Paik Hospital. There were 10 males and 20 females whose mean age was 22.42±6.84 years ranging from 17 to 51. All patients underwent bilateral thoracic sympathectomy under semi-sitting position and two 5 mm sized trocars were inserted. Result: Mean operation time was 52.32±11.72 minutes and the mean elevation of palmar temperature after sympathectomy was 2.17±0.47℃. Eighteen patients(60%) complained compensatory hyperhidrosis. All patients except one were able to discharge at the operation day or postoperative one day. There were no recurrence during follow up from 2 to 8 months(mean 5.30±2.17 months). Conclusion: Thoracoscopic sympathectomy is simple and effective technique in hyperhidrosis and widely applied indication will be necessary. We conclude that further discussion should be made about the resection area and method to get maximal effect and minimal side effect.