• Journal of the Society of Naval Architects of Korea
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• v.33 no.1
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• pp.98-108
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• 1996

In the reliability analysis of general structures, the limit state equations are implicit and cannot be described in closed form. Thus, sampling methods such as the Crude Monte-Carlo simulation, and probabilistic FEM are often used, but these methods are not so effective in view of computational cost, because a number of structural analysis are required and the derivatives must be calculated for probabilistic FEM. Alternatively the response surface approach, which approximates the limit state surface by using several results of structural analysis in the region adjacent to MPFP, could be applied effectively. In this paper, the central composite design, Bucher-Bourgund method and the approximation method using artificial neural network are studied for the calculation of probability of failure by the response surface method. Through the example comparisons, it is found that Bucher-Bourgund method is very effective and Neural network method for the reliability analysis is comparable with other methods. Specially, the central composite design method is found to be rational and useful in terms of mathematical consistency and accuracy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.779-783
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• 2002

The dielectric breakdown of epoxy composites used for transformers was experimented and then its data were simulated by Weibull distribution probability. As a result, first of all, speaking of dielectric breakdown properties, the more hardener increased the stronger breakdown strength at low temperature because of cross-linked density by the virtue of ester radical. And the breakdown strength of specimens with filler was lower than it of non-filler specimens because it is believed that the adding filler forms interface and charge is accumulated in it, therefore the molecular motility is raised, the electric field is concentrated, and the acceleration of electron and the growth of electron avalanche are early accomplished. In the case of filled specimens with treating silane, the breakdown strength become much higher since this suggests that silane coupling agent improves interfacial combination and relaxs electric field concentration. Finally, from the analysis of weibull distribution, it was confirmed that as the allowed breakdown probability was given by 0.1%, the applied field value needed to be under 21.5MVcm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10A
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• pp.1139-1146
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• 2004

An abrupt increase of traffic-load in cellular CDMA systems can cause overload, as a result, degrade the quality of service (QoS) and the spectrum utilization due to lacking radio resources in base stations. In this paper, we propose a joint coverage and resource management (JCRM) scheme which can improve the QoS degradation and the spectrum utilization. The JCRM scheme hands over the overloaded traffic to neighboring cells by virtually reducing overloaded cell coverage and extending neighboring cell coverage, as well the scheme allocates radio resources based on the necessary handover probability. The proposed scheme can be applied to the existing cellular CDMA systems as well as adaptive coverage management schemes for next generation mobile communication systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5C
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• pp.505-513
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• 2009

This paper proposes a real-time foreground segmentation and background substitution method for protecting the privacy on visual communication. Previous works on this topic have some problems with the color and shape of foreground and the capture device such as stereo camera. we provide a solution which can segment the foreground in real-time using fixed mono camera. For improving the performance of a foreground extraction, we propose the Temporal Foreground Probability Model (TFPM) by modeling temporal information of a video. Also we provide an boundary processing method for natural and smooth synthesizing that using alpha matte and simple post-processing method.

• The KIPS Transactions:PartB
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• v.16B no.6
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• pp.463-470
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• 2009

In this paper, we propose the advanced fire-flame detection algorithm using camera image for better performance than previous sensors-based systems which is limited on small area. Also, previous works using camera image were depend on a lot of heuristic thresholds or required an additional computation time. To solve these problems, we use statistical values and divide image into blocks to reduce the processing time. First, from the captured image, candidate flame regions are detected by a background model and fire colored models of the fire-flame. After the probability models are formed using the change of luminance, wavelet transform and the change of motion on time axis, they are used for membership function of fuzzy logic. Finally, the result function is made by the defuzzification, and the probability value of fire-flame is estimated. The proposed system has shown better performance when it compared to Toreyin's method which perform well among existing algorithms.

• Geotechnical Engineering
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• v.2 no.3
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• pp.67-78
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• 1986

This paper presents how to determine the system reliability of a typical shallow foundation constituted four potential correlated failure modes of hearing capacity (BCM), consolidation settlement (CSM), moment (MFM), and tension shear (PCM). Through the idenfication of the distinct and different modes and evaluation of range of system reliability, the obtained conclusions are as follows; 1. The CSM and the PCM are the lowest and highest of reliability indices of single performance function, and the BCM and the MFM are medium of them. 2. For the correlated failure modes, the hi-modal bounds Is narrower and lower of failure probability than the unimodal bounds. Not to be overestimated, therefore, the system reliability should be based on the second-order bounds using correlated performance functions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.124-131
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• 2015

In this paper, we proposed indoor positioning system using RSS(Received Signal Strength) positioning method and TSS(Transmission Signal Strength). The main point in the paper is to improve reliability of accuracy positioning with the area recognition algorithm and probabilistic algorithm, which can be effectively used indoor. In the test in 1-dimensional or 2-dimensional spaces, also we checked effective positioning system considered environment of propagation that is changed by reflection, refraction and multipath in according to space form. It is necessary to find place where urgent situation happen and quickly to respond the situation for patients or the weak. Therefore, we expect the positioning system proposed can apply to the field of traffic IT.

• The KIPS Transactions:PartB
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• v.18B no.1
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• pp.39-44
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• 2011

In this paper, we propose a method to improve the Firefly Algorithm(FA) introduced by Xin-She Yang, recently. We design and analyze the improved firefly algorithm based on the heuristic. We compare the FA with the Particle Swarm Optimization (PSO) which the problem domain is similar with the FA in terms of accuracy, algorithm convergence time, the motion of each particle. The compare experiments show that the accuracy of FA is not worse than PSO's, but the convergence time of FA is slower than PSO's. In this paper, we consider intuitive reasons of slow convergence time problem of FA, and propose the improved version of FA using a partial mutation heuristic based on the consideration. The experiments using benchmark functions show the accuracy and convergence time of the improved FA are better than them of PSO and original FA.

• Archives of design research
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• v.17 no.1
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• pp.119-126
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• 2004

MMO RPG Online game as a new means of human computer interaction has been made rapid progress. Even though many kinds of online game have published, few games are being well received by its user. So we have a problem to be solved what is the fundamentals to attract game users. I will apply a game theory of the Roger Caillois who lived as an typical french thinker. Although Roger Caillois had never experienced a computer game since he died at 1978, his game theory was acknowledged that a game can be classified into four sections to grab the human's interest related with culture. Four sections of game were consisted of Ilinx, Mimicry, Alea, and Agon. The competition with people in game is essential to "Agon" that which stands on the basis of a pride when one is definitely superior to the others. In same way, "Alea" is that which stands on the basis of fortune, Mimicry is that which stands on the basis of simulation, Ilinx is that which stands on the basis of dizzy. In conclusion, I will explain that a game theory of the Roger Caillois is useful tool for deveoper to understand game fundamentals.d game fundamentals.

• Smart Media Journal
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• v.7 no.2
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• pp.54-59
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• 2018

With the increasing use of touch-enabled mobile devices such as smartphones and tablet PCs, the works are done on desktop computers and smartphones, and tablet PCs perform laptops. However, due to the nature of smart devices that require portability, QWERTY keyboard is densely arranged in a small screen. This is the cause of different typographical errors when using the mechanical QWERTY keyboard. Unlike the mechanical QWERTY keyboard, which has enough space for each button, QWERTY keyboard on the touch screen often has a small area assigned to each button, so that it is often the case that the surrounding buttons are input rather than the button the user intends to press. In this paper, we propose a method to automatically correct the input errors of the QWERTY keyboard in the touch screen environment by using the n-gram language model using the word unigram and the bigram probability.