• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권7호
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• pp.3171-3191
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• 2016

Due to growing demand on wireless data traffic, a large number of different types of base stations (BSs) have been installed. However, space-time dependent wireless data traffic densities can result in a significant number of idle BSs, which implies the waste of power resources. To deal with this problem, we propose an active state control algorithm based on semi-Markov decision process (SMDP) for a heterogeneous network. A MDP in discrete time domain is formulated from continuous domain with some approximation. Suboptimal on-line learning algorithm with a random policy is proposed to solve the problem. We explicitly include coverage constraint so that active cells can provide the same signal to noise ratio (SNR) coverage with a targeted outage rate. Simulation results verify that the proposed algorithm properly controls the active state depending on traffic densities without increasing the number of handovers excessively while providing average user perceived rate (UPR) in a more power efficient way than a conventional algorithm.

• Proceedings of the KIEE Conference
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.587-590
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• 1988

In the case of VLSI computer system control unit design using PLA, optimal state code assignment algorithm to minimize the PLA area is proposed. An optimal state code assignment algorithm which considers output state and logic minimization simultaneously is proposed, and by means of this, algorithm product term is minimized. Also, by means of this algorithm running time and memory capacitance is decreased as against heuristic state code assignment algorithm which uses matrix calculation and considers the constraint relation only. This algorithm is implemented on VAX 11/750 (UNIX4.3BSD). Through the various test example applied proposed algorithm, the efficiency of this algorithm is shown.

• International Journal of Control, Automation, and Systems
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• 제4권5호
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• pp.645-652
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• 2006

In this paper a new type of filter, called the $H_2/H_{\infty}$ FIR filter, is proposed for discrete-time state space signal models. The proposed filter requires linearity, unbiased property, FIR structure, and independence of the initial state information in addition to the performance criteria in both $H_2$ and $H_{infty}$ sense. It is shown that $H_2,\;H_{\infty}$, and $H_2/H_{\infty}$ FIR filter design problems can be converted into convex programming problems via linear matrix inequalities (LMIs) with a linear equality constraint. Simulation studies illustrate that the proposed FIR filter is more robust against temporary uncertainties and has faster convergence than the conventional IIR filters.

• Journal of Information Processing Systems
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• 제18권1호
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• pp.48-58
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• 2022

Blind restoration for motion-blurred images is always the research hotspot, and the key for the blind restoration is the accurate blur kernel (BK) estimation. Therefore, to achieve high-quality blind image restoration, this thesis presents a novel windowed-total-variation method. The proposed method is based on the spatial scale of edges but not amplitude, and the proposed method thus can extract useful image edges for accurate BK estimation, and then recover high-quality clear images. A large number of experiments prove the superiority.

• Journal of the Korean Society for Precision Engineering
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• 제26권3호
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• pp.55-67
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• 2009

This paper addresses the dynamic consideration of the athletic constraints on skating motion. In order to generate a human-like skating motion, the athletic constraints are distinctively analyzed into dynamic constraints and physical constraints. A close investigation of the athletic constraints evolved valid extent of dominant parameter for a leg muscle. During the human-like skating motion, the state of actuation was shifted from region of maximum force to region of maximum power. Simulation results were intuitively comprehensible, and the effectiveness of analytic algorithm was demonstrated for skating motion.

• Journal of Korean Society of Transportation
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• 제11권2호
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• pp.63-84
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• 1993

The main purpose of this paper is to develop a route guidance system which is a part of the intelligent vehicle-highway system and to apply to a real world in order to evaluate usefulness of the system. To this end, significant literature review works with regard to vehicle navigation and route guidance systems were conducted and have provided an important information about state-of-the-art systems developed and tested by the advanced countries. A geographic information system, called INTGIS, was used to find the shortest path in a given road network. Three scenarios to find minimum path were simulated and observed : 1) with-constraint on intersections and road segments, 2) without-constraint on intersections and road segments, and 3) via several stops from origin to destination. Based on a series of experiments, the results indicate that the route guidance system developed in this research is very useful to inform drivers on highway and arterial the traffic informations such as congestion and incident.

• International Journal of Aeronautical and Space Sciences
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• 제12권1호
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• pp.16-23
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• 2011

In this paper, nonlinear model predictive control (NMPC) is addressed to develop formation guidance for multiple unmanned aerial vehicles. An NMPC algorithm predicts the behavior of a system over a receding time horizon, and the NMPC generates the optimal control commands for the horizon. The first input command is, then, applied to the system and this procedure repeats at each time step. The input constraint and state constraint for formation flight and inter-collision avoidance are considered in the proposed NMPC framework. The performance of NMPC for formation guidance critically degrades when there exists a communication failure. In order to address this problem, the modified optimal guidance law using only line-of-sight, relative distance, and own motion information is presented. If this information can be measured or estimated, the proposed formation guidance is sustainable with the communication failure. The performance of this approach is validated by numerical simulations.

• Journal of Computing Science and Engineering
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• 제3권4호
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• pp.260-277
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• 2009

In this paper we propose a model for checking integrity constraints of mobile databases called Three-Level (3-L) model, wherein the process of constraint checking to maintain the consistent state of mobile databases is realized at three different levels. Sufficient and complete tests proposed in the previous works together with the idea of caching relevant data items for checking the integrity constraints are adopted. This has improved the checking mechanism by preventing delays during the process of checking constraints and performing the update. Also, the 3-L model reduces the amount of data accessed given that much of the tasks are performed at the mobile host, and hence speeds up the checking process.

• Structural Engineering and Mechanics
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• 제35권1호
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• pp.83-98
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• 2010

In this paper, the mass optimization of four bar linkages is carried out using genetic algorithms (GA) with single and dual constraints. The single constraint of bending stress and the dual constraints of bending and buckling stresses are imposed. From the movement response of the bar linkage mechanism, the analysis of the mechanism is developed using the combination of kinematics, kinetics, and finite element analysis (FEA). A penalty-based transformation technique is used to convert the constrained problem into an unconstrained one. Lastly, a detailed comparison on the effect of single constraint and of dual constraints is presented.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 한국항해항만학회 2004년도 춘계학술대회 논문집
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• pp.451-456
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• 2004

This study was performed to analyze the operation system of transfer crone to improve the reality of yard operation roles in container terminal and present the applicable method of operation rules to apply the operation priority. And we derived the procedure to estimate the maximum number of waiting truck based on the waiting of truck and the occupancy of driving lane in yard, and analyzed the constraint state of space. To solve the space constraint, we provided a multi-job principle to define the space resource and described the solution and sequence diagram for the principle.