• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.3
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• pp.272-275
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• 2014

An improved fuzzy Kalman filtering speed estimation scheme was proposed by means of measuring stator side voltage and current value based on vector control state equation of induction motor. The designed fuzzy adaptive controller conducted recursive online correction of measurement noise covariance matrix by monitoring the ratio of theory residuals and actual residuals to make it approach real noise level gradually, allowing the filter to perform optimal estimation to improve estimation accuracy of EKF. Meanwhile, co-simulation scheme based on MATLAB and Ansoft was proposed in order to improve simulation accuracy. Field-circuit coupling problems of induction motor under the action of vector control were solved and the parameter optimization accuracy was improved dramatically. The simulation and experimental results show that this algorithm has a strong ability to inhibit the random measurement noise. It is able to estimate motor speed accurately, and has superior static and dynamic characteristics.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.4
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• pp.381-388
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• 1997

This paper proposes a heuristic algorithm to efficiently perform line balancing in the PCB assembly line including multiple surface mounters efficiently. Generally, the problems in line balancing are classified into two kinds. Firstly, is the determining of the minimum number of machines required for achieving the desired production rate. Secondly, is the assign of jobs to multiple machines in order to minimize the cycle time which is defined as a maximum among the working times of machines when the number of machines is fixed. In this paper, we deal with the latter. We consider a PCB assembly line, including the multiple surface mounters arranged serially as a target system. Also, the conveyor is assumed to move at a constant speed and have no buffer. Considering that the minimum number of machines required for the desired production rate is a discrete nonincreasing function which is inversely proportional to the cycle time, we propose an optimization algorithm for line balancing by using the binary search method. The algorithm is validated through computer simulation, the results of which show that their shapes coincide nearly with those of optimal line balancing efficiency graphs regardless of the number of components, the performance of surface mounters, and the structure of assembly line.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.3
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• pp.60-73
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• 1997

By introducing a compressive-strained quanternary InGaAsP quantum-wells instead of a conventional ternary InGaAs quantum-wells in 1.55.mu.m DFB-LD, the lasing performances canb e improved and the problems caused by the thickness non-uniformity and the compositional abruptness among the hetero-interpaces canb e relaxed. In this paper, we investigated an iptimum InGaAsP/InGaAsP multiple-quantum-well(MQW) structure as an active layer in a direct-modulated 1.55.mu. DFB-LD from the view point of threshold current, chirping charcteristics, and resonance frequency. The optimum compressive-strained MQW structure was revealed as InGaAsP/InGaAsP structure with strain amount of about 1.2%, number of wells $N_{w}$ of 7, well width $L_{w}$ of 58.agns.. The threshold current density J of 500A/c $m^{2}$, the linewidth enhancement factor a of 1.8, and differential resonance frequency of d $f_{r}$/d(I-I)$^{1}$2/=2GHz/(mA)$^{1}$2/(atI=2 $I_{th}$) were expected in 1.55.mu.m .gamma./4-shifted DFB-LD with the cavity length of 400.mu.m long and kL value of 1.25. These values are considerably improved ones compared to those of 1.55um DFB-LD with InGaAs/InGaAsP MQW which have enhancement factor and the resonance frequence frequency by the detuning of lasing wavelength and gain-peak wavelength. It was found that the linewidth enhancement factor of 20% and differential resonance frequency of 35% without the degradation of the threshold current density could be enhanced in the range of -15nm~-20nm detuning which can be realized by controlling the thickness and Incomposition of InGaAsP well. well.and Incomposition of InGaAsP well. well.

• Convergence Security Journal
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• v.13 no.3
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• pp.85-90
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• 2013

To provide high-quality services, national public institutions and companies have provided information and materials over the internet network. However, a risk of malware infection between transmission and reception of data leads to exposure to various security threats. For this reason, national institutions have proceeded with projects for network separation since 2008, and data linkage has been made using network connection storage through network separation technologies, along with physical network separation. However, the network connection storage has caused waste of resources and problems with data management due to the presence of the same data in internal network storage and external network storage. In this regard, this study proposes a method to connect internal and external network data using NAS storage as a way to overcome the limitations of physical network separation, and attempts to verify the priority of items for the optimization of network separation by means of AHP techniques.

• KSBB Journal
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• v.15 no.2
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• pp.181-187
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• 2000

The production of heterologous protein using GAL promoter in conventional S. cerevisiae has several problems to s이ve for c commercialization. In this research, S. cerevisiae mutant(reg1-501, gaI1), which cannot use galactose and has alleviated g glucose repression level, is used as host for optimizing induction of GAL promoter. In this experiment, the effects of specific g growth rate on specific recombinant protein expression rate were tested in both cases and optimum fed batch fermentation m method was obtained in both cases. Through these experiments, optimum condition of recombinant protein production by G GAL promoter using S. cerevisiae mutant (reg1-501, gal1) were found.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.3
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• pp.27-42
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• 1984

The complexity and expensiveness of water resources projects have made optimum operation and design by computer-based techniques of increasing interest in recent years. Water resources problems in real world need many decisions under numerous constraints. In addition there are nonlinearities in the state and return function. This mathematical and technical troublesome must be overcome so that the optimum operation polices are determined. Then traditional dynamic optimization method encountered two major-cruxes: variable discretization and appearance of constraints. Even several recent methods which based on the Differential Dynamic Programming(DDP) have some difficulties in handling of constraints. This paper has presented New DDP which is applicable to multi-reservoir control. It is intended that the method suggested here is superior to abailable alternatives. This belief is supported by analysis and experiments(New DDT does not suffer course of dimensionality and requires no discretization and is able to handle easily all constraints nonlinearity).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.8
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• pp.873-879
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• 2012

Metamodels have been developed with a variety of design optimization techniques in the field of structural engineering over the last decade because they are efficient, show excellent prediction performance, and provide easy interconnections into design frameworks. To construct a metamodel, a sequential procedure involving steps such as the design of experiments, metamodeling techniques, and validation techniques is performed. Because validation techniques can measure the accuracy of the metamodel, the number of presampled points for an accurate kriging metamodel is decided by the validation technique in the sequential kriging metamodel. Because the interpolation model such as the kriging metamodel based on computer experiments passes through responses at presampled points, additional analyses or reconstructions of the metamodels are required to measure the accuracy of the metamodel if existing validation techniques are applied. In this study, we suggest a sensitivity validation that does not require additional analyses or reconstructions of the metamodels. Fourteen two-dimensional mathematical problems and an engineering problem are illustrated to show the feasibility of the suggested method.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.7
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• pp.669-674
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• 2013

A three-dimensional hydrogel scaffold has been proposed for the effective production of biomimetic intestinal villi to reduce ethical and cost problems caused by animal testing in pharmaceutical development. This study explores an experimental approach to develop a new technique based on laser machining and microdrilling processes to produce a plastic mold for the fabrication of a three-dimensional hydrogel scaffold. For process optimization, both the laser machining and the microdrilling experiments are conducted by varying the experimental conditions, and structural characterization of the mold and intestinal villi were performed using SEM (scanning electron microscope) and OM (optical microscope) images. Polycarbonate (PC) was used as a candidate material. The experimental results show that intestinal villi can be fabricated by both laser and microdrilling machining processes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.81-87
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• 2017

This paper describes the dynamic behavior and enhancement of Korean high-speed trains. The tail vibration reduction method of the yaw damper installation method change, which was derived from previous research, was applied to the running test of high-speed train. In addition, the vibration reduction method for the entire vehicle was derived by a numerical method and its effect was confirmed by a running test. The improved design was applied to the double-deck high-speed train coaches and the commissioning proceeded without problems in dynamic behavior. Sensitivity analysis of the suspension parameters affecting the critical speed of Korean next-generation high-speed trains was performed and four design variables that greatly affected the critical speed were derived. These were in the order of the primary elastic joint x-directional stiffness, the secondary yaw damper series stiffness, the secondary lateral damper damping coefficient, and the carbody damper damping coefficient. By optimizing the design variables, the suspension parameter that improves the critical speed by 23.3% can be used in the commercial designs of Korean next-generation high-speed trains.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.3
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• pp.564-570
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• 2006

This paper presents a new real-time system design methodology for embedded system as well as event-driven real time application. It is required to implement a deadline handling mechanism in order to satisfy a large-scale distributed real time application. When we design real time system, it has handled a deadline and is important to measure / control a timing issue. These timing constraints usually associated with an interface between model and system. There are many case tools that supporting a real time application, for example, UML, graphic language for designing real time system, but they cannot provide efficient way to handle deadline miss. Therefore, users have to design deadline handler manually when they need to use it. This paper contributes solving the problems of user-level deadline handling for an embedded system. Also, it also discusses an efficient deadline handler design mechanism using on RoseRT, which is a graphical CASE tool supporting from UML.