• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.465-470
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• 2007

The co-channel interference is a primary factor of loss in multimedia mobile communications. In this paper, we present a performance of the frequency reuse partitioning to refrain the co-channel interference and maximize system performance. First, we analyze the co-channel interference using the frequency reuse partitioning through the statistical modeling. From this results, we decide on the frequency reuse partitioning for the system throughput which is maximized. Finally, analysis and simulation results show that the frequency reuse partitioning based cellular system can mitigate the co-channel interference and maximize the system throughput. The experimental results show that system throughput is maximized from 0.7 to 0.8 according to traffic road. We can maximize the system throughput using the results with cellular system design parameter.

• Journal of Korea Game Society
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• v.7 no.2
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• pp.11-20
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• 2007

This paper proposes a real-time simulation technique for thin shells undergoing large deformation. Shells are thin objects such as leaves and papers that can be abstracted as 2D structures. Development of a satisfactory physical model that runs in real-time but produces visually convincing animation of thin shells has been remaining a challenge in computer graphics. Rather than resorting to shell theory which involves the most complex formulations in continuum mechanics, we adopt the energy functions from the discrete shells proposed by Grinspun et al. For real-time integration of the governing equation, we develop a modal warping technique for shells. This new simulation framework results from making extensions to the original modal warping technique which was developed for the simulation of 3D solids. We report experimental results, which show that the proposed method runs in real-time even for large meshes, and that it can simulate large bending and/or twisting deformations with acceptable realism.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.1
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• pp.26-34
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• 1998

In this paper, we confirm that the instanteneous phase current of the bifilar-wound hybrid stepping motor is dependent of lead angle by the experimental results. The variation of phase current with lead angle gives informations about the rotor position at the moment when phase winding coil is excited. We show that the rotor position of the bifilar-wound hybrid stepping motor for the closed-loop drives can be detected by using the instantaneous phase current measurement. We propose an instantaneous phase current equation as the function of electrical lead angle by the modeling of the bifilar-wound hybrid stepping motor. We also analyze the relationship between instantaneous phase current and rotor position by the computer simulation results. By the experimental results, we also confirm that the information about the rotor position can be obtained from the instantaneous phase current values at the instance of $\pi/2$ electrical angle of excitation pulse. pulse.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.1145-1148
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• 2005

In this paper, we introduce a probabilistic model based on Bayesian networks (BNs) for inferring human fatigue by integrating information from various visual cues and certain relevant contextual information. Visual parameters, typically characterizing the cognitive states of a person including parameters related to eyelid movement, gaze, head movement, and facial expression, serve as the sensory observations. But, an individual visual cue or contextual Information does not provide enough information to determine human fatigue. Therefore in this paper, a Bayesian network model was developed to fuse as many as possible contextual and visual cue information for monitoring human fatigue. At the experiment results, display the utility of the proposed BNs for predicting and modeling fatigue.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.2
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• pp.109-118
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• 2012

As a result of the prevalence of smartphone, various mobile services became faster by LTE networks. Because many mobile devices are used more wireless services, heavy signaling traffic for authentication could be generated. Authentication is an important factor in wireless networks to identify devices; it is the start of wireless networks. This paper analyzes previous patterns for more effective authentication in accessing of another external networks. We propose a fast authentication scheme for minimizing of signaling cost between the authentication server and external networks. And we calculate the rate of authentication occurrence in LTE networks using mathematical modeling as well as the change of signaling cost for authentication in various network environments. Finally, we calculate the optimized number of authentication data and show the effectiveness for authentication signaling costs.

• The KIPS Transactions:PartA
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• v.12A no.2 s.92
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• pp.171-180
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• 2005

In distributed systems data are replicated and stored at several nodes to increase the availability and overall performance. Here Quorum protocol doffing a certain set of replicas required for read/write operation exists for global concurrency control. One of the representative replication Protocols - the Tree Quorum protocol - has a drawback of rapidly growing number of replicas as the level increases, while the Grid protocol requires the same operation cost even without any failure. In this paper, thus, we propose a new replication protocol called hybrid protocol which capitalizes the merits of the existing protocols and solves the problems of them at the same time. The proposed hybrid protocol has very low operation cost in the absence of failure like the tree quorum protocol, and has relatively lower operation cost and higher availability than existing protocols when failure occurs by employing tree architecture as the overall organization while each level of the tree is organized as a row of a grid architecture. It is thus effective to be applied to survival storage system. We conduct cost and availability analysis of the proposed protocol through mathematical modeling, and response time and throughput are compared with those of the Tree Quorum protocol through computer simulation.

• Journal of Energy Engineering
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• v.16 no.4
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• pp.187-193
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• 2007

Water hammer following the tripping of pumps can lead to overpressures and negative pressures. Reduction in overpressure and negative pressure may be necessary to avoid failure, to improve the efficiency of operation and to avoid fatigue of system components. The field tests on the water hammer have been conducted on the pump rising pipeline system with an air chamber. The hydraulic transient is modeled using the method of characteristics. Minimizing the least squares problem representing the difference between the measured and predicted transient response in the system performs the calibration of the simulation program. Among the input variables used in the water hammer analysis, the effects of the polytropic exponent, the discharge coefficient and the wave speed on the result of the numerical analysis were examined. The computer program developed in this study will be useful in designing the optimum parameters of an air chamber for the real pump pipeline system. The correct selection of air chamber size and the effects of related parameters to minimize water hammer have been investigated by both field measurements and numerical modeling.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.3 s.162
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• pp.463-474
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• 2007

With rapid expansion in e-retailing of apparel business, personalized fitting model service shows the possibility as the differentiated marketing strategy in cyber shopping. According as necessity of personalized fitting model construction rises, it is tried personalized fitting model creation in several fields such as computer engineering, mechanical engineering, information engineering. But, because existent study was concentrated only on human body modeling, it does not reflect average morphological characteristics of human body properly. In this study, we wish to examine if morphing is fit for expressing characteristic of average human body shape and suggest desirable morphing. We used 3-D scan data of 254 Korean middle aged men collected by Size Korea 2004. The result of this study are as follows: Lower body types were categorized by height hip girth and lower drop(hip girth-navel girth) which were main factors of lower body shape. Then each factor was divided into 3 groups respectively, 30% in the middle, over 30%, under 30%. In 27 groups, the group which belonged to 30% in the middle of height, 30% in the middle of hip girth, 30% in the middle of lower drop was selected as a representative group. We tested geometrical figure by differ volume, tilt, position of point. And we created a representative type of men's lower bodies by morphing the representative group and analyzed it's horizontal, vertical sections. A representative type which was created by morphing reflected a real body and changed realistically at the part of hip, crotch, calf muscle and so on. A cross sections of a representative type were similar to average cross sections of the representative group in size and shape. So it was proved that morphing was successful.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.8-15
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• 2007

Freeway corridors consist of urban freeways and parallel arterials that drivers can use alternatively. Ramp metering in freeways and signal control in arterials are contemporary traffic control methods that have been developed and applied in order to improve traffic conditions of freeway corridors. However, most of the existing studies have focused on either optimal ramp metering in freeways, or progression signal strategies between arterial intersections. There have been no traffic control systems in Korea that integrates the freeway ramp metering and arterial signal control. The effective control strategies for freeway operations may cause negative effects on arterial traffic. On the other hand, traffic congestion and bottleneck phenomenon of arterials due to the increasing peak-hour travel demand and ineffective signal operation may generate an accessibility problem to freeway ramps. Thus, the main function of the freeway which is the through-traffic process has not been successful. The purpose of this study is to develop an integrated control model that connects freeway ramp metering systems and signal control systems in arterial intersections. And Optimization of integrated control model which consists of ramp metering and signal control is another purpose. The design of experiment, neural network, and simulated annealing are used for optimization.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.4
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• pp.168-176
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• 2005

We propose a method for 3-dimensionally reconstructing an object using a line that includes the midpoint information from a single image. A pre-defined polygon is used as the primitive and the recovery is processed from a single image. The 3D reconstruction is processed by mapping the correspondence point of the primitive model onto the photo. In the recent work, the reconstructions of camera parameters or error minimizing methods through iterations were used for model-based 3D reconstruction. However, we proposed a method for the 3D reconstruction of primitive that consists of the segments and the center points of the segments for the reconstruction process. This method enables the reconstruction of the primitive model to be processed using only the focal length of various camera parameters during the segment reconstruction process.