• Journal of the Korean Operations Research and Management Science Society
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• v.39 no.1
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• pp.13-27
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• 2014

In this paper, we deal with a Steiner Ring Star (SRS) problem arising from the design of survivable telecommunication networks. We develop two mixed integer programming formulations for the SRS problem by implementing Miller-Tucker-Zemlin (MTZ) and Sarin-Sherali-Bhootra (SSB) subtour elimination constraints, and then apply the reformulation-linearization technique (RLT) to enhance the lower bound obtained by the LP relaxation. By exploiting the ring-star structure of underlying network, we devise some valid inequalities that tighten the LP relaxation. Computational results demonstrate the effectiveness of the proposed solution procedure.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.8
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• pp.98-104
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• 2013

AC machines are in wide use in industry and d-q transformation from 3 phase of a, b, c is commonly used to analyze these kinds of machines. The equivalent circuits of d and q axis are, however, generally cross coupled and difficult to analyze. In this study, a modeling technique of AC machine including induction and PM synchronous motors using matrix vector is proposed. With that model, it can not only explain the AC machines physically but also make it simple to analyze them. The separating process of d and q components is not needed in this model and this model can be applied to analyze asymmetric motors like IPMSM machine. With this technique, the model becomes simple, easy to understand physically, and yields results that are the same as those from other models. These simulation results of the proposed model for induction motor are compared with those of other models to verify the method proposed.

• Journal of Power Electronics
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• v.14 no.6
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• pp.1130-1138
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• 2014

This study analyzes a ladder multilevel converter (double ladder topology) with the use of a new averaging modeling technique. This technique introduces an analytical method to compute for the switching losses and is used to conduct an in-depth analysis of the influence of the switching frequency and parasitic resistance of components on converter efficiency. The obtained results enable the selection of switches and switching frequency to minimize losses. Moreover, simulation results and experimental measurements validate the analytical calculations.

• The Journal of the Acoustical Society of Korea
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• v.11 no.1E
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• pp.56-63
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• 1992

The poblem of active oise control has been analysed using a adaptive signal processing technique. In this methods, the adaptive signal processor or model predicts the primary sound wave travelling along the acoustic plant and generates the secondary source 180° out of phase which attempts to attempts to attenuate the undesired noise by destructive interference. In the solutions presented here, acoustic propagation delay is considered as a part of the model which used the FIR filter. The effects of error path and auxiliary path transfer functioin are anayzed and a new on=-line technique for error path modeling, adaptive delayed inverse modeling is presented. In this study, using these new concepts, our system can more reduce the noise level in duct to 5dB-15dB than only using LMS algorithm system.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.624-627
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• 1992

Mathematical modeling is majorly divided into three parts: the derivation of models, the fitting of models to data, and the simulation of data from models. This paper focuses on the parameter optimization which is necessary for the fitting of models to data. The method of simulated annealing(SA) is a technique that has recently attracted significant attention as suitable for optimization problem of very large scale. If the temperature is too high, then some of the structure created by the heuristic will be destroyed and unnecessary extra work will be done. If it is too low then solution is lost, similar to the case of a quenching cooling schedule in the SA phase. In this study, therfore, we propose a technique of determination of the starting temperature and cooling schedule for SA phase.

• Journal of the Korean Society for Railway
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• v.5 no.4
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• pp.231-236
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• 2002

Todays, crash safety requirements of the railway vehicle structures become important design criterion according to the increased driving speed and the lightweight construction. Although the crash analysis using computer simulation can be effectively applied to predict the crash performance of the railway vehicles in the early design stage, the optimized design w.r.t the crash safety could be realized by the crash tests with actual prototype vehicles. However, it is very expensive and time-consuming task to perform the crash test of the railway vehicles. As a measure to cope with the problem, in this paper, the scale modeling technique is suggested and experimentally verified to predict the impact energy absorption characteristics of full scale model of aluminum extrusions sub-structures and the high-speed railway vehicle structure.

• Journal of KSNVE
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• v.9 no.1
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• pp.103-112
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• 1999

A new modeling and analysis technique for one-dimensional distributed parameter systems is presented. First. discretized equations of motion in Laplace domain are derived by applying discretization methods for partial differential equations of a one-dimensional structure with respect to spatial coordinate. Secondly. the z and inverse z transformations are applied to the discretized equations of motion for obtaining a dynamic matrix for a uniform element. Four different discretization methods are tested with an example. Finally, taking infinite on the number of step for a uniform element leads to an exact dynamic matrix for the uniform element. A generalized modal analysis procedure for eigenvalue analysis and modal expansion is also presented. The resulting element dynamic matrix is tested with a numerical example. Another application example is provided to demonstrate the applicability of the proposed method.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2004.10a
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• pp.310-315
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• 2004

The objective of this study was to provide the optimum thawing condition under different level of high pressure(50, 100, 150 and 200 MPa) using high pressure assisted technique which can improve the quality of frozen and thawed pork. The calculated thawing rate from the results depending on the high pressure showed the strong trend of increased thawing rate under pressurized condition(P<0.05). And then, the numerical modeling was executed to predict the thawing rate influenced by the pressure level using exponential regression, LnY=0.70623 + 0.00433 ${\cdot}$ P ($R^2=0.9985$), and it was fairly fit for the functional relation between the thawing rate(Y) and pressure(P) with comparatively high coefficient, $R^2$ of determination.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.171-174
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• 2003

Shortest path problems are among the most studied network flow optimization problems, with interesting applications in various fields. One such field is the route determination service, where various kinds of shortest path problems need to be solved in location-based service. Our research aim is to propose a route technique in real-time location-based service (LBS) environments according to user's route preferences such as shortest, fastest, easiest and so on. Turn costs modeling and computation are important procedures in route planning. We propose a new rest modeling method for turn costs which are traditionally attached to edges in a graph. Our proposed route determination technique also has an advantage that can provide service interoperability by implementing XML web service for the OpenLS route determination service specification.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.187-192
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• 2009

This paper presents a method for designing a robust controller that alleviates disturbance effects and compensates performance degradation owing to the time-delay. Disturbance observer(DOB) approach as a tool of robust control has been widely employed in industry. However, since the Pade approximation of time-delay makes the plant non-minimum phase, the classical DOB cannot be applied directly to the system with time-delay. By using a new DOB structure for non-minimum phase systems together with the Smith Predictor, we propose a new controller for reducing the both effects of disturbance and time-delay. Moreover, the closed-loop system can be made robust against uncertain time-delay with the help of a Pill controller tuning method that is based on a second-order plus dead time modeling technique.