• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.252-254
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• 2005

Completer coverage path planning requires the robot path to cover every part of the workspace, which is an essential issue in cleaning robots and many other robotic applications such as vacuum robots and painter robots. In this paper, a novel Water Flowing Algorithm (WFA) is proposed for cleaning robots to complete coverage path planning in unknown environment without obstacles. The robot covers the whole workspace just like that water fills up a container. First the robot goes to the lowest point in the workspace just like water flows to the bottom of the container. At last the robot will come to highest point in the workspace just like water overflows from the container and simultaneously the robot has covered the whole workspace. The computer simulation results show that the proposed algorithm enable the robot to plan complete coverage paths.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.330-335
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• 2000

Faults detection and containment requirements are typically allocated from a top-level specification as a percentage of total faults detection and containment, weighted by failure rate. This faults detection and containments are called as a fault coverage. The fault coverage requirements are typically allocated identically to all units in the system, without regard to complexity, cost of implementation or failure rate for each units. In this paper a simple methodology and mathematical model to support the allocation of system fault coverage rates to lower-level units by considering the inherent differences in reliability is presented. The models are formed as a form of constrained optimization. The objectives and constraints are modeled as a linear form and this problems are solved by linear programming. It is identified by simulation that the proposed solving methods for these problems are effective to such requirement allocating.

• Journal of Communications and Networks
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• v.16 no.5
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• pp.493-501
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• 2014

Coverage completeness is an important indicator for quality of service in wireless sensor networks (WSN). Due to limited energy and diverse working conditions, the sensor nodes have different lifetimes which often cause network holes. Most of the existing methods expose large limitation and one-sidedness because they generally consider only one aspect, either coverage rate or energy issue. This paper presents a novel method for coverage hole detection with residual energy in randomly deployed wireless sensor networks. By calculating the life expectancy of working nodes through residual energy, we make a trade-off between network repair cost and energy waste. The working nodes with short lifetime are screened out according to a proper ratio. After that, the locations of coverage holes can be determined by calculating the joint coverage probability and the evaluation criteria. Simulation result shows that compared to those traditional algorithms without consideration of energy problem, our method can effectively maintain the coverage quality of repaired WSN while enhancing the life span of WSN at the same time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.8
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• pp.1823-1832
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• 1997

In this ppaer, fault coverage analysis of a conformance test case for communication protocols, specified as a deterministic finite state machine(DFSM) is presented. The fault coverage analysis of a test case is defined by measuring the extent of the faults detected using a generated test case. The method that evaluates fault coverage analysis for a test case, has been researched by arithmetic analysis and simulation. In this paper, we designed and implemented a simulator for fault coverage analysis of a communication protocol teat case. With this result for Inres protocol, output fault and state merge and split fault have a high fault coverage of 100%. This simulator can be widely used with new fault coverage analysis tools by applying it to various protocols.

• Journal of the Korean Society for Railway
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• v.10 no.2 s.39
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• pp.231-242
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• 2007

As railroad industry faces the new Renaissance era, effective and efficient maintenance methods for rolling stock operation are required with advanced railroad technology. All kinds of railroad systems such as high-speed long-distance train, metropolitan mass transit and light rail require systematic maintenance technology in order to maintain the safe railroad operation. Simulation models for regular operations of the example maintenance center are developed. In this study, standard maintenance procedures, layout, equipments, and number of workers of Siheung Metropolitan Railroad Maintenance Rolling Stock Depot are considered. The proposed simulation models are developed using simulation package ARENA. After simulation, four types of observations are analyzed. First, the bottleneck operation is identified. Second, the relationship between maintenance center size, number of workers and cycle time is analyzed. Third, the scheduling performances between PERT/CPM and Critical Chain Project Management(CCPM) are compared. Lastly, the simulation results according to worker's working coverage shows expanding the worker's coverage decreases the cycle time and increases throughput per train. However, workers are to be fully trained to do multiple skill work.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.5
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• pp.687-692
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• 1998

Test pattern generation is one of most difficult problems encountered in automating the design of logic circuits. The goal is to obtain the highest fault coverage with the minimum number of test patterns for a given circuit and fault set. although there have been many deterministic algorithms and heuristics the problem is still highly complex and time-consuming. Therefore new approach-es are needed to augment the existing techniques. This paper considers the problem of test pattern improvement for combinational circuits as a restricted subproblem of the test pattern generation. The problem is to maximize the fault coverage with a fixed number of test patterns for a given cir-cuit and fault set. We propose a new approach by use of a genetic algorithm. In this approach the genetic algorithm evolves test patterns to improve their fault coverage. A fault simulation is used to compute the fault coverage of the test patterns Experimental results show that the genetic algorithm based approach can achieve higher fault coverages than traditional techniques for most combinational circuits. Another advantage of the approach is that the genetic algorithm needs no detailed knowledge of faulty circuits under test.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.44-49
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• 2009

In this study, we performed urrban climate simulation how both the factor of environmental land and artificial factors influence on the formation of urban temperature. With deducing quantitative data, this study could get more accurate results of the urban temperature using urban climate simulation system. In the case of natural land cover, it appeared that there are effects on the lowering temperature and the lower temperature rate appeared in the water land cover on the whole. This is considered as temperature in water land was low because of the characteristics of water land having evaporation latent heat was high and convective sensible heat was low. In case of building which has building coverage ratio, 5% with 10 floors and building coverage ratio, 15 % with 6 floors, it appears that the temperature in the water land is $33.6^{\circ}C$. In case of building coverage ratio 5%, temperature dropped when buildings has more than 4 stories. This is regarded as the size of building is bigger, the temperature dropped in relatively because of the fluctuation of the rate of solar heat from the land. At the present time, the urban temperature are higher because of various artificial factors in the city. With these results, this study supposed to be a basies of the future studies for considering both the composition of building coverate ratio and floor plan.

• Journal of the Korean Statistical Society
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• v.29 no.1
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• pp.17-27
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• 2000

In this paper, we develop noninformative priors that are used for estimating the reliability of stress-strength system under the Burr-type X model. A class of priors is found by matching the coverage probabilities of one-sided Bayesian credible interval with the corresponding frequentist coverage probabilities. It turns out that the reference prior as well as the Jeffreys prior are the second order matching prior. The propriety of posterior under the noninformative priors is proved. The frequentist coverage probabilities are investigated for samll samples via simulation study.

• Journal of the Korean Data and Information Science Society
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• v.13 no.2
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• pp.235-242
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• 2002

In this paper, we develop noninformative priors that are used for estimating the ratio of failure rates under Freund's bivariate exponential distribution. A class of priors is found by matching the coverage probabilities of one-sided Baysian credible interval with the corresponding frequentist coverage probabilities. Also the propriety of posterior under the noninformative priors is proved and the frequentist coverage probabilities are investigated for small samples via simulation study.

• Journal of Communications and Networks
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• v.18 no.5
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• pp.773-783
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• 2016

Both coordinated multi-point transmission and frequency reuse are effective approaches to mitigate inter-cell interference and improve network coverage. The motivation of this work is to explore the manner to effectively utilize the spectrum resource by reasonably combining cooperation and frequency reuse. The $Mat{\acute{e}}rn$ cluster process, which is appropriate to model networks with hot spots, is used to model the spatial distribution of base stations. Two cooperative mechanisms, coherent and non-coherent joint transmission (JT), are analyzed and compared. We also evaluate the effect of multiple antennas and imperfect channel state information. The simulation reveals that the proposed approach to combine cooperation and frequency reuse is effective to improve the network coverage for users located at both the center and the boundary of the cooperative region.