• Polymer(Korea)
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• v.36 no.5
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• pp.593-598
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• 2012

Solution polymerization behaviors of L-lactide using single and mixed aluminium catalyst systems were studied. Triisobutylaluminium (TIBA) was a reference catalyst for mixing. For the $Al(O-i-Pr)_3$/TIBA catalytic systems, the molecular weight of the resulting polylactide (PLA) decreased as the composition of $Al(O-i-Pr)_3$ increased. The higher molecular weight shoulder was revealed in their GPC curve. At TIBA of 80 mol% a bimodal GPC curve was shown. The conversion in the trimethylaluminium (TMA)/TIBA catalysts system decreased as the composition of TMA in the mixed catalyst increased. The conversion in the trioctylaluminium (TOA)/TIBA catalysts system decreased as the composition of TOA in the mixed catalyst increased. The unimodal molecular weight distribution was observed with the TOA/TIBA catalyst systems. The Al compounds-mixed catalyst could produce a higher molecular weight shoulder in the GPC curve.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1113-1118
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• 2004

This paper presents the dynamic analysis method for an electromechanical system. The engineer has at his disposal a variety of software simulation tools. However, difficulties arise when the study of the behavior of complex electromechanical systems in combination with coupling element is required. Typical examples of such systems are machines for factory automation, home automation, and office automation. Dynamic systems analysis packages or electronic systems analysis packages offer the restrictive to simulate these mixed systems such electromechanical product. Electronic circuit analysis algorithm is easily incorporated into a multi-body dynamics analysis algorithm. The governing equation of electronic circuit is formulated as a differential algebraic equation form including both electrical and mechanical variables and is simultaneously solved in every time step. This analysis method clearly demonstrates the application potential for mixed electromechanical simulation.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.5
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• pp.733-745
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• 2001

This review paper discusses the relevance and potential importance of food-feed systems in Asian agricultural systems, and in particular the role and contribution of legumes to these systems. A food-feed system is one that maintains, if not increases, the yield of food crops, sustains soil fertility, and provides dietary nutrients for animals. It involves a cropping pattern within which the feed crop has many beneficial effects without competing for land, soil nutrients and water with the food crops. The agricultural environment is described with reference to the priority agro-ecological zones and prevailing mixed farming systems in Asia. Within these systems, animal production is severely hampered by critical feed shortages which can however, be alleviated by the integration of suitable leguminous forages into the cropping systems. The review also focuses on the role and potential importance of leguminous forages in terms of biodiversity, their uses in farming systems, beneficial effects on animal performance, and draws attention to six case studies in different countries that clearly demonstrate many benefits of developing such food-feed systems. Considerable opportunities exist for widening the use of forage legumes in the development of systems with several complementary advantages (e.g. fenceline, cover crops, fodder banks, forage source and erosion control) to improve the development of sustainable crop-animal systems in Asia.

• Journal of applied mathematics & informatics
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• v.30 no.5_6
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• pp.699-717
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• 2012

In this paper, we deal with the robust mixed $H_2/H_{\infty}$ guaranteed-cost control problem involving uncertain neutral stochastic distributed delay systems. More precisely, the aim of this problem is to design a robust mixed $H_2/H_{\infty}$ guaranteed-cost controller such that the close-loop system is stochastic mean-square exponentially stable, and an $H_2$ performance measure upper bound is guaranteed, for a prescribed $H_{\infty}$ attenuation level ${\gamma}$. Therefore, the fast convergence can be fulfilled and the proposed controller is more appealing in engineering practice. Based on the Lyapunov-Krasovskii functional theory, new delay-dependent sufficient criteria are proposed to guarantee the existence of a desired robust mixed $H_2/H_{\infty}$ guaranteed cost controller, which are derived in terms of linear matrix inequalities(LMIs). Furthermore, the design problem of the optimal robust mixed $H_2/H_{\infty}$ guaranteed cost controller, which minimized an $H_2$ performance measure upper bound, is transformed into a convex optimization problem with LMIs constraints. Finally, two simulation examples illustrate the design procedure and verify the expected control performance.

• Environmental Engineering Research
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• v.24 no.2
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• pp.309-317
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• 2019

This study evaluated the kinetics of acrylamide (AM) biodegradation by mixed culture bacteria and Enterobacter aerogenes (E. aerogenes) in sequencing batch reactor (SBR) systems with AQUASIM and linear regression. The zero-order, first-order, and Monod kinetic models were used to evaluate the kinetic parameters of both autotrophic and heterotrophic nitrifications and both AM and chemical oxygen demand (COD) removals at different AM concentrations of 100, 200, 300, and 400 mg AM/L. The results revealed that both autotrophic and heterotrophic nitrifications and both AM and COD removals followed the Monod kinetics. High AM loadings resulted in the transformation of Monod kinetics to the first-order reaction for AM and COD removals as the results of the compositions of mixed substrates and the inhibition of the free ammonia nitrogen (FAN). The kinetic parameters indicated that E. aerogenes degraded AM and COD at higher rates than mixed culture bacteria. The FAN from the AM biodegradation increased both heterotrophic and autotrophic nitrification rates at the AM concentrations of 100-300 mg AM/L. At higher AM concentrations, the FAN accumulated in the SBR system inhibited the autotrophic nitrification of mixed culture bacteria. The accumulation of intracellular polyphosphate caused the heterotrophic nitrification of E. aerogenes to follow the first-order approximation.

• Transactions on Control, Automation and Systems Engineering
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• v.3 no.3
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• pp.139-145
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• 2001

In this paper, we consider the H$_2$(or guaranteed cost control) and H$_{\infty}$ controller design methods for singular(or descriptor) systems with input time delay. Also, a mixed H$_2$and H$_{\infty}$ controller design algorithm is treated by combination of the proposed H$_2$and H$_{\infty}$ controller design method. The sufficient conditions for the existence of controllers and controller design methods are introduced at each Lemma and Theorem. Furthermore, we present optimization problems to get the upper bound of performance measures. The proposed methods are checked by examples.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.5
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• pp.10-16
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• 1996

In this paper, we consider a generalized mixed H_2/H_{\infty}$ output feedback problem. It is finding an internally stabilizing controller that minimizes a mixed $H_{2}$/ $H_{performance}$ measure. We show that a generalized mixed H_2/H_{\infty}$ system with two exogenous inputs and two controlled signals is transformed into auxiliary system with two exogenous inputs and one controlled signal. The two systems have equivalent performance. Therefore, a complete solution of generalized mixed H_2/H_{\infty}$ output feedback problem is achieved by existing results of mixed H_2/H_{\infty}$ control theory.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.48
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• pp.299-310
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• 1998

Actually mixed assembly line is mixed with open and close type workstation. This workstation is called hybridworkstation. The propose of this paper is to determine the sequencing of model that minimize line length for actual(hybridworkstation) mixed model assembly line. we developed three mathematical formulation of the problem to minimize the overall length of a line with hybrid station. Mathematical formulation classified model by operato schedule. Mixed model assembly line is combination program and NP-hard program. Thus computation time is often a critical factor in choosing a method of determining the sequence. This study suggests a tabu search technique which can provide a near optimal solution in real time and use the hill climbing heuristic method for selecting initial solution. Modified tabu search method is compared with MIP(Mixed Integer Program). Numerical results are reported to demonstrate the efficiency of the method.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.6
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• pp.602-608
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• 2014

Mixed-model production lines are often used in manufacturing systems. In production lines, different product types are simultaneously manufactured by processing small batches. This paper describes a new welding assembly technology involving the development of experimental models for a mixed-model production line in an automobile company. Due to the extensive number of models, the design of a welding assembly system is complicated. Performance evaluation is an important phase in the design of welding assembly lines in a mixed-model production environment. In this study, a new welding assembly technology for a mixed-model production method was used to weld the package tray and dash panel of a vehicle.

• Food Science and Biotechnology
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• v.16 no.6
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• pp.1069-1071
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• 2007

The frequency independent critical concentration (Cc) of xanthan and carob (X/C) mixed gel was determined based on the Winter-Chambon's theory. X/C mixed (X/C=1:1 ratio) gels were prepared from 0.1 to 1% of concentration. The linear viscoelastic properties, i.e., storage and loss modulus, of X/C mixed gel at $20^{\circ}C$ were measured by frequency sweep tests. The frequency independence of tangent function of phase angle (tan ${\delta}$) of X/C mixed gels was graphically determined from the intersection of the plot of phase angle against concentration at varied frequencies. The intersection (C=0.43%) was considered to be Cc of X/C mixed gel.