• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.12
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• pp.884-893
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• 1988

Adaptive controllers for linear unknown coefficient system, that is corrupted by disturbance, are designed by parameter adaptation model reference adaptive control(MRAC). This design is stemmed from the Lyapunov direct method. To reduce the model following error and to improve the convergence rate of the design, an indirect-suboptimal control law is derived. Proper compensation for the effects of time-varying coefficients and plant disturbance are suggested. In the design procedure no complete identification of unknown coefficients are required.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.13-13
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• 2000

This paper considers delay-dependent guaranteed cost control for uncertain time-delay systems with norm-bounded parametric uncertainties. A new delay-dependent condition for the existence of the guaranteed cost control law is presented in terms of linear matrix inequalities (LMI). An algorithm involving convex optimization is proposed to design a controller which guarantees the suboptimal minimum of the guaranteed cost of the closed-loop system for all admissible uncertainties.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.81-84
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• 1990

This paper presents a method of sub-optimal control for nonlinear systems via block pulse transformation. The adaptive optimal control scheme proposed by J.P. Matuszewski is introduced to minimize the performance index. The proposed method is simple and computationally advantageous. Viablity of the this method is established with simulation results for the van der Pole equation for comparision with other methods.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.509-512
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• 2000

In this paper, the RBF-based multiuser detector (MUD) is proposed for a multirate DS/CDMA system. The performance of RBF-based MUD is compared with that of many suboptimal multiuser detectors in terms of bit error probability. From the simulation results, it is confirmed that the RBF-based multiuser detector outperforms decorrelating detector, and achieves near-optimum performance in several situations. The results in this paper can be applied to design of MUD fur a multirate DS/CDMA system.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.10
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• pp.733-739
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• 1988

Adaptive controllers for linear system whose nominal values of coefficients only are known, that is corrupted by disturbance, are designed by signal synthesis model reference adaptive control (MRAC). This design is stemmed from the Lyapunov direct method. To reduce the model following error and to improve the conrergence rate of the design, an indirect suboptimal control law is de rived using the Hamilton Jacobi Beellman equation. Proper compensaton for the effects of time varying coefficients and plant disturbance are suggested. In the design procedure no complete identification of unknown coefficients are required.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.454-456
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• 1998

Traditional adaptive control algorithms are not robust to dynamic uncertainties. The adaptive control algorithms developed previously to deal with dynamic uncertainties do not facilitate quantitative design. We proposed a new robust adaptive control algorithms consists of an $H^{\infty}$ suboptimal control law and a robust parameter estimator. Numerical examples showing the effectiveness of the $H^{\infty}$ adaptive scheme are provided.

• Korean Journal of Bronchoesophagology
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• v.16 no.2
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• pp.105-108
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• 2010

The prevalence of gastroesophageal reflux disease(GERD) has been increased recently in Korea. Most patients who have GERD are well treated by medication. But patients who have suboptimal disease control under medical therapy are needed further treatment. Nowadays minimally invasive surgery using laparoscopy and thoracoscopy has become popular in the operation of GERD although antireflux surgery is vary. Antireflux surgery is a well-documented, effective therapeutic alternative to control GERD.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.12
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• pp.1273-1279
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• 1991

In this paper new adaptive approach method for sub optimal control of nonlinear systems is presented. This paper used the method proposed by J.P.Matuszewski for adaptive optimal control scheme and used block pulse transformations for solving the Riccati differential equation which is usually quite this method is estabilished with simulation results and comparisons to existing approaches.

• Journal of Korean Neurosurgical Society
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• v.57 no.4
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• pp.250-257
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• 2015

Objective : Endovascular treatment of wide-necked intracranial aneurysms is a challenge and the durability and the safety of these treated aneurysms remain unknown. The aim of this study was to evaluate the clinical and long-term angiographic results of wide-necked intracranial aneurysms treated with coil embolization. Methods : Between January 2002 and December 2012, 53 wide-necked aneurysms treated with coil embolization were selected. Forty were female, and 13 were male. Twenty eight (52.8%) were ruptured aneurysms, and 25 (47.2%) were unruptured aneurysms. The patents' medical and radiological records were reviewed retrospectively. Results : Of the 53 aneurysms, coiling alone was employed in 45 (84.9%) and stent-assisted coiling was done in 8 (15.1%). The initial angiographic results revealed Raymond class 1 (complete occlusion) in 30 (56.6%) cases, Raymond class 2 (residual neck) in 18 (34.0%) cases, and Raymond class 3 (residual sac) in 5 (9.4%) cases. The mean angiographic follow-up period was 37.9 months (12-120 months). At the last angiographies, Raymond class 1 was seen in 26 (49.1%) cases, Raymond class 2 in 16 (30.2%), and Raymond class 3 in 11 (20.8%). Angiographic recurrence occurred in 22 (41.5%) patients, with minor recurrence in 7 (13.2%) cases and major recurrence in 15 (28.3%). Retreatment was performed in 8 cases (15.1%). A suboptimal result on the initial angiography was a significant predictor of recurrence in this study (p=0.03). Conclusion : The predictor of recurrence in wide-necked aneurysms is a suboptimal result on the initial angiography. Long-term angiographic follow-up is recommended in wide-necked aneurysms.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.5
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• pp.351-358
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• 2013

A suitable supply of mineral elements into shoot via a root system from growth media makes plants favorable growth and yield. The shortage or surplus of minerals directly affects overall physiological reactions to plants and, especially, strongly influences carbohydrate metabolism as a primary response. We have studied mineral uptake and synthesis and translocation of soluble carbohydrates in N, P or K-deficient tomato plants, and examined the interaction between soluble carbohydrates and mineral elements. Four-weeks-old tomato plants were grown in a hydroponic growth container adjusted with suboptimal N ($0.5mmol\;L^{-1}\;Ca(NO_3)2{\cdot}4H_2O$ and $0.5mmol\;L^{-1}\;KNO_3$), P ($0.05mmol\;L^{-1}\;KH_2PO_4$), and K ($0.5mmol\;L^{-1}\;KNO_3$) for 30 days. The deficiency of specific mineral element led to a significant decrease in its concentration and affected the concentration of other elements with increasing treatment period. The appearance of the reduction, however, differed slightly between elements. The ratios of N uptake of each treatment to that in NPK sufficient tomato shoots were 4 (N deficient), 50 (P deficient), and 50% (K deficient). The P uptake ratios were 21 (N deficient), 19 (P deficient), and 28% (K deficient) and K uptake ratios were 11 (N deficient), 46 (P deficient), and 7% (K deficient). The deficiency of mineral elements also influenced on carbohydrate metabolism; soluble sugar and starch was substantially enhanced, especially in N or K deficiency. In conclusion, mineral deficiency leads to an adverse carbohydrate metabolism such as immoderate accumulation and restricted translocation as well as reduced mineral uptake and thus results in the reduced plant growth.