• Wind and Structures
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• 제5권2_3_4호
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• pp.369-378
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• 2002

The application of Large Eddy Simulation (LES) in a curvilinear coordinate system to the flow around a square cylinder is presented. In order to obtain sufficient resolution near the side of the cylinder, we use an O-type grid. Even with a curvilinear coordinate system, it is difficult to avoid the numerical oscillation arising in high-Reynolds-number flows past a bluff body, without using an extremely fine grid used. An upwind scheme has the effect of removing the numerical oscillations, but, it is accompanied by numerical dissipation that is a kind of an additional sub-grid scale effect. Firstly, we investigate the effect of numerical dissipation on the computational results in a case where turbulent dissipation is removed in order to clarify the differences between the effect of numerical dissipation. Next, the applicability and the limitations of the present method, which combine the dynamic SGS model with acceptable numerical dissipation, are discussed.

• 한국경영과학회지
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• 제36권4호
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• pp.81-89
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• 2011

In recent business environments, the competition among firms is shifting from the competition based on individual firm only to the competition based on alliance of firms. This is because it is not easy for a firm to perform all functions which consumers want. Thus, it is more effective to combine core competencies of different firms based on a strategic partnership. It is essential to establish a strategic partnership and this strategic partnership is a key success factor in PSS(Product-Service System) which combines products and services. In this paper, we propose a profit sharing model for PSS partnership. We first analyze customer's utility using Cobb-Douglas utility function and then propose the PSS profit sharing ratio considering functionalities and cost structures based on the combination ratio of PSS. This paper helps firms to develop partnership strategies for PSS.

• Korean Journal of Mathematics
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• 제6권1호
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• pp.27-46
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• 1998

We are concerned with an optimal control problem governed by a Poisson equation in which body force acts like a control parameter. The cost functional to be optimized is taken to represent the error from the desired observation and the cost due to the control. We recast the problem into the mixed formulation to take advantage of the minimax principle for the duality method. The existence of a saddle point for the Lagrangian shall be shown and the optimality system will be derived therein. Finally, to attain an optimal control, we combine the optimality system with an operational technique. By achieving the gradient of the cost functional, a convergent algorithm based on the projected gradient method is established.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.970-972
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• 1998

In practice, there may be various defects in an insulating system, so that the PD signals can be produces from these defect simultaneously. Regarding these situations, we have to discriminate the type of defect as well as to determine whether the PD occurs or not. In our research. some analysis results of the PD signals from multi-defects insulating system will be presented. We measure the PD signals using three kind of electrode system: IEC(b). Needle-Plane and mixed electrodes. To simulate multi-defect systems, we combine two electrode systems and apply test voltage simultaneously. Neural network, statistical analysis methods will be tested, and the possibilities and limitations of each method will be clarified.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 추계학술대회 논문집
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• pp.147-148
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• 2012

Recently, hybrid generation systems combine multiple energy sources or storage components to optimize the characteristics of the individual energy sources. In this paper, a battery integrated PV power optimizer for PV-battery hybrid power generation system is proposed. PV system using proposed topology can easily increase battery capacity and remove high power bidirectional converter to control bulky battery bank.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1990년도 제11회 학술강연회초록집
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• pp.7-31
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• 1990

Tribologicsl diagnostics as the ensemble of means and methods of continuous monitoring of the state of friction characteristics of moving junctions is playing an ever important part in the development of friction, lubrication, and wear theory end practice. The scheme presenting the main areas of tribological diagnostics is given in Fig. I. This growing part of TD is determined by the general tendency of modern technology, expressed in an attempt to organically combine the functions of measuring, evaluating,and predicting the parameters and characteristics of the processee taking place in the operating device. The logical result of this integration in future is the closed system correcting its operation in accordance with sn established program. Unfortunately, tribotechnicsl devices are still very far from such an ideal system at the present time. While in the friction assemblies with hydrodynamic lubrication it is possible in the first approximation to realize feed-backs in the lubricant circulation system with the aid of monitoring of the pressure, temperature and filtration, in the systems operating without lubrication and with boundary lubricetion even the process of selection of the diagnostic parameters has not been completed.

• 한국해양공학회지
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• 제12권3호통권29호
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• pp.103-111
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• 1998

This paper describes the initial hull form design process which generate a hull form using a neurofuzzy modeling. Neurofuzzy system is to combine the merits of fuzzy inference system and neural networks. Therefore it has structured knowledge representations as well as adaptive capacities. Initial hull form design stage is the process which generate an adoptable hull form from the limited design information and multi-decidions condidering correlations with design factors. It can be assidted efficiently by neurofuzzy system. This paper suggests two methods of an initial hull form generation using the neurofuzzy modeling and B-spline theory. and examines the usefulness of suggested method through its application examples.

• International Journal of Ocean System Engineering
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• 제2권1호
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• pp.16-23
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• 2012

In this paper we discussed a new methodology for Urdu Character Recognition system using Dempster-Shafer theory which can powerfully estimate the similarity ratings between a recognized character and sampling characters in the character database. Recognition of character is done by five probability calculation methods such as (similarity, hamming, linear correlation, cross-correlation, nearest neighbor) with Dempster-Shafer theory of belief functions. The main objective of this paper is to Recognition of Urdu letters and numerals through five similarity and dissimilarity algorithms to find the similarity between the given image and the standard template in the character recognition system. In this paper we develop a method to combine the results of the different distance measurement methods using the Dempster-Shafer theory. This idea enables us to obtain a single precision result. It was observed that the combination of these results ultimately enhanced the success rate.

• ETRI Journal
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• 제39권3호
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• pp.364-372
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• 2017

For the reliability of controllers in a software defined network (SDN), a dynamic and self-learning schedule method (DSL) is proposed. This method is original and easy to deploy, and optimizes the combination of multiple controllers. First, we summarize multiple controllers' combinations and schedule problems in an SDN and analyze its reliability. Then, we introduce the architecture of the schedule method and evaluate multi-controller reliability, the DSL method, and its optimized solution. By continually and statistically learning the information about controller reliability, this method treats it as a metric to schedule controllers. Finally, we compare and test the method using a given testing scenario based on an SDN network simulator. The experiment results show that the DSL method can significantly improve the total reliability of an SDN compared with a random schedule, and the proposed optimization algorithm has higher efficiency than an exhaustive search.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.212-217
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• 2004

In general, the braking system of high speed train has an important role for the safety of the train. To stop safely train at its pre-decided position, it is necessary to combine properly the various brakes. The prototype of Korean high speed train (KHST) has been designed, fabricated and tested by the domestic researchers. It has adopted a combined electrical brakes, such as rheostatic brake, regenerative brake and eddy current brake, and mechanical brakes composed of disc brake, wheel disc brake and tread brake. In this paper, the performances and control algorithms of braking system have been reviewed by the experimental method.