• Journal of information and communication convergence engineering
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• v.6 no.2
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• pp.222-227
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• 2008

The important problem in designing a Fuzzy Logic Controller(FLC) is generation of fuzzy control rules and it is usually the case that they are given by human experts of the problem domain. However, it is difficult to find an well-trained expert to any given problem. In this paper, I describes an application of genetic algorithm, a well-known global search algorithm to automatic generation of fuzzy control rules for FLC design. Fuzzy rules are automatically generated by evolving initially given fuzzy rules and membership functions associated fuzzy linguistic terms. Using genetic algorithm efficient fuzzy rules can be generated without any prior knowledge about the domain problem. In addition expert knowledge can be easily incorporated into rule generation for performance enhancement. We experimented genetic algorithm with a non-trivial vehicle controling problem. Our experimental results showed that genetic algorithm is efficient for designing any complex control system and the resulting system is robust.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.483-487
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• 1994

In this paper, we analize the effect of a steering water used in a unified phase I-phase II semi-infinite constrained optimization algorithm and present a new algorithm based on the facts that when the point x is far away from the feasible region where all the constraints are satisfied, reaching to the feasible region is more important than minimizing the cost function and that when the point x is near the region, it is more efficient to try to reach the feasible region and to minimize the cost function concurrently. Also, the angle between the search direction vector and the gradient of the cost function is considered when the steering parameter value is computed. Even though changing the steering parameter does not change the rate of convergence of the algorithm, we show through some examples that the proposed algorithm performs better than the other algorithms.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.2
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• pp.1-6
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• 1982

This paper reviews and describes some applications of perturbation theory in the practical analysis of linear systems which involve random parameters. Statistical measures of the system outputs are derived in terms of statistical measures of the system parameters and inputs (i.e., in the way of perturbed linear operator equations). Perturbed state transition matrix is also derived. With simple first-order and second-order linear system models, we compare the accuracy of perturbation results with the exact ones. And the convergence of perturbation series is also investigated.

• Journal of information and communication convergence engineering
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• v.2 no.4
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• pp.209-213
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• 2004

With the commercialization of CDMA 2000-1x late in 2000, a high-speed wireless Internet, based on a mobile communication networks, appeared in Korea. This will develop into the next-generation of mobile communications(4G) in the future and the new cell layout will be required the cellular configuration of 4G. We would need the legislation with respect to base-stations and to building the mobile communication networks, as well as the optimization of mobile communication systems. In this study, in order to provide 4G, I examined and analyzed that the current laws & regulations related to licensing and operating a mobile communication base-stations in KOREA.

• Journal of information and communication convergence engineering
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• v.2 no.4
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• pp.214-218
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• 2004

In this paper, we have analyzed TCP performance over wireless correlated fading links with and without Snoop protocol. For a given value of the packet error rate, TCP performance without Snoop protocol is degraded as the fading is getting fast (i.e. the user moves fast). When Snoop protocol is introduced in the base station, TCP performance is enhanced in most wireless environments. Especially the performance enhancement derived from using Snoop protocol is large in fast fading channel. This is because packet errors become random and sporadic in fast fading channel and these random packet errors (mostly single packet errors) can be compensated efficiently by Snoop protocol's local packet retransmissions. But Snoop protocol can't give a large performance improvement in slow fading environments where long bursts of packet errors occur. Concerning to packet error rate, Snoop protocol results in the highest performance enhancement in the channel with mid-high values of packet error rate. This means Snoop protocol cannot fully fulfill its ability under too low or too high packet error rate environments.

• Journal of the Korean Statistical Society
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• v.28 no.2
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• pp.235-251
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• 1999

In this paper we examine extremal behavior of a $textsc{k}$th-order stationary Markov chain {X\ulcorner} by considering excesses over a high level which typically appear in clusters. Excesses over a high level within a cluster define a cluster damage, i.e., a normalized sum of all excesses within a cluster, and all excesses define a damage point process. Under some distributional assumptions for {X\ulcorner}, we prove convergence in distribution of the cluster damage and obtain a representation for the limiting cluster damage distribution which is well suited for simulation. We also derive formulas for the mean and the variance of the limiting cluster damage distribution. These results guarantee a compound Poisson limit for the damage point process, provided that it is strongly mixing.

• Tunnel and Underground Space
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• v.8 no.2
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• pp.130-138
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• 1998

Comprehensive monitoring system for the safe and economical excavation of underground opening has been established by employing the 3 independent models each of which can i) predict the ultimate convergence, ii) assess the in-situ stresses and the elastic modulus of excavating rock, iii) calculate the time-dependent opening behavior with respect to the face advance rate and support pressure at the equilibrium state. Accuracy of each model has been verified through illustrative examples. The step-by-step procedures of comprehensive monitoring system for analyzing the rock behavior and the optimum support installation has been explained. The capability and applicability of this system to the practical excavation also has been discussed.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.234-235
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• 2018

본 논문에서는 R.Box와 연결되어 미세먼지정보를 무선으로 전송하는 아두이노 기반의 시스템을 제안한다. R.Box는 라즈베리파이를 기반으로 다양한 센서로 구성된 일반목적의 IoT 허브이다. 아두이노와 미세먼지센서를 이용해 미세먼지농도를 측정하고 데이터를 WiFi를 통해 R.Box로 전송한다. 아두이노와 R.Box는 TCP 소켓 방식으로 통신하며 이 시스템을 통하여 원하는 위치의 미세먼지정보를 확인할 수 있다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2017.07a
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• pp.156-157
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• 2017

최근 스마트 기기의 발달과 센서들의 보급으로 인해 이들을 이용한 IoT(Internet of Things, 사물인터넷)가 빠르게 발전하면서 센서를 활용한 서비스 특화 디바이스들이 출시되어 IoT 플랫폼 및 서비스 시장 규모가 급격히 확대되고 있다. 본 논문에서는 센서간의 원활한 연결을 위해 센서들을 통합하고 관리할 수 있으며, 다양한 서비스에 적용될 수 있는 일반 목적의 IoT 허브를 구현해보았다. 라즈베리 파이를 기반으로 한 IoT 허브는 다양한 센서들의 정보를 수집해 센서 데이터를 서버에 전송하는 역할을 하며, 센서 관리를 위한 기능도 포함되어 있다.

• Journal of Ubiquitous Convergence Technology
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• v.2 no.1
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• pp.40-50
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• 2008

The problem of assigning customers to satellite channels is a difficult combinatorial optimization problem and is NP-complete. For this combinatorial optimization problem, standard optimization methods take a large computation time and so genetic algorithms (GA) and ant colony optimization (ACO) can be used to obtain the best and/or optimal assignment of customers to satellite channels. In this paper, we present a comparative study of GA and ACO to this problem. Various issues related to genetic algorithms approach to this problem, such as solution representation, selection methods, genetic operators and repair of invalid solutions are presented. We also discuss an ACO for this problem. In ACO methodology, three strategies, ACO with only ranking, ACO with only max-min ant system (MMAS), and ACO with both ranking and MMAS, are considered. A comparison of these two approaches (i,e., GA and ACO) with the standard optimization method is presented to show the advantages of these approaches in terms of computation time.