• International Journal of Fuzzy Logic and Intelligent Systems
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• v.9 no.2
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• pp.141-146
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• 2009

Support vector machine is a classification algorithm based on statistical learning theory. It has shown many results with good performances in the data mining fields. But there are some problems in the algorithm. One of the problems is its heavy computing cost. So we have been difficult to use the support vector machine in the dynamic and online systems. To overcome this problem we propose to use stratified sampling of statistical sampling theory. The usage of stratified sampling supports to reduce the size of training data. In our paper, though the size of data is small, the performance accuracy is maintained. We verify our improved performance by experimental results using data sets from UCI machine learning repository.

• Journal of ILASS-Korea
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• v.5 no.2
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• pp.28-34
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• 2000

To reduce the soot and NOx simultaneously, a new system of stratified injection is developed. This system discharges stratified diesel-methanol in a D. I. Diesel Engine. Nozzle and delivery valve of conventional injection system were remodeled to inject diesel and methanol from one injector sequently. The quantity of diesel and methanol was controled precisely by micrometers mounted on the injection control lack. The real injection ratio of dual fuel was measured by volumetric ratio. We could confirm the capabilities that soot and NOx simultaneously were reduced by diesel-methanol stratified injection from the results of in-cylinder pressure data obtained from combustion experiment by stratified injection, heat release rate and mass fraction bumed.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.147-150
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• 1996

This paper describes controller design and implementation method for controlling the temperature distribution in a thermal stratified wind tunnel(TSWT) by using a neural network algorithm. It is impossible to derive a mathematical model of the relation between heat inputs and temperature outputs in the test section of the TSWT governed by a nonlinear turbulent flow. Thus inverse neural network models with a multi layer perceptron structure are used in a feedforward control loop and feedback control loop to generate an arbitrary temperature distribution in the test section of the TSWT.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.13 no.21
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• pp.81-90
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• 1990

In stratified random sampling a simple random sample must be taken in each stratum to reduce the maximum gain in precision given the minimum cost. The purpose of this paper is to deal with the propertics of the estimates and variances and obtain the economic design of stratified random sampling through the optimum allocation of the sample sizes. In addition, the between stratum variation and the within stratum variation is stratifying the population are described.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.219-224
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• 1998

We introduce the notion of ${\gamma}$-fuzzy filter and ${\gamma}$-limit structure to L-fuzzy point. We show that the category ${\gamma}$Lim of ${\gamma}$-limit spaces is a cartesian closed topological construct containing the category LFTop of stratified L-fuzzy topological spaces as a bireflective subcategory.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.9 no.1
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• pp.36-41
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• 2009

Self organizing map(SOM) is one of the unsupervised methods based on the competitive learning. Many clustering works have been performed using SOM. It has offered the data visualization according to its result. The visualized result has been used for decision process of descriptive data mining as exploratory data analysis. In this paper we propose improvement of SOM using stratified sampling of statistics. The stratification leads to improve the performance of SOM. To verify improvement of our study, we make comparative experiments using the data sets form UCI machine learning repository and simulation data.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.11
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• pp.4453-4468
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• 2015

This paper investigates optimization-based base station (BS) placement. An optimization model is defined and the BS placement problem is transformed to a lexicographical stratified programming (LSP) model for a given trajectory, according to different accuracy requirements. The feasible region for BS deployment is obtained from the positioning system requirement, which is also solved with signal coverage problem in BS placement. The LSP mathematical model is formulated with the average geometric dilution of precision (GDOP) as the criterion. To achieve an optimization solution, a tolerant factor based complete stratified series approach and grid searching method are utilized to obtain the possible optimal BS placement. Because of the LSP model utilization, the proposed algorithm has wider application scenarios with different accuracy requirements over different trajectory segments. Simulation results demonstrate that the proposed algorithm has better BS placement result than existing approaches for a given trajectory.

• Journal of ILASS-Korea
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• v.7 no.3
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• pp.31-37
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• 2002

In previous study, diesel-methanol stratified injection system is manufactured and applied to a D.I. diesel engine in order to realize combustion improvement using methanol, which is oxygenated fuel with large latent heat. We know that NOx and soot is reduced by stratified injection of diesel fuel-methanol. Therefore, in the present study, combustion diagnosis using optical measurement is tried to make clear effect of methanol on simultaneous reduction of NOx and soot. Two-color method is used to measure flame temperature and KL value, which is approximately proportional to the soot consentration along the optical path. Laser induced scattering method was used to measure distribution of soot at two dimensional area. Also, it is compared exhaust characteristics of NOx and soot with results of optical measurement.

• Journal of computational fluids engineering
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• v.7 no.3
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• pp.35-43
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• 2002

This paper addresses a numerical method for predicting transient temperature distributions in the wall of a curved pipe subjected to internal laminar thermally-stratified flow. A simple and convenient numerical method of treating the unsteady conjugate heat transfer in non-orthogonal coordinate systems is presented. Numerical calculations are performed for the transient evolution of thermal stratification in two curved pipes, where one has thick wall and the other has so thin wall that its presence can be negligible in the heat transfer analysis. The predicted results show that the thermally stratified flow and transient conjugate heat transfer in a curved pipe with a finite wall thickness can be satisfactorily analyzed by the present numerical method, and that the neglect of wall thickness in the prediction of pipe wall temperature distributions can provide unacceptably distorted results for the cases of pipes with thick wall such as safety related-piping systems of nuclear power plant.

• Nuclear Engineering and Technology
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• v.17 no.1
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• pp.34-44
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• 1985

The main purpose of this work is to study the effects of (1) configuration, size, and materials of electrodes, (2) flow pattern, (3) electrode position with respect to a dielectric boundary on the void fraction measurement and flow regime characterization by capacitance transducers. From the experimental results, relationships between the measured relative capacitance and void fraction are obtained for both annular and stratified flow systems under static condition, and this result is compared with theoretical predictions. From this study it can be concluded that (1) the strip-type electrodes are more sensitive than ring-type electrodes for both annular and stratified flows, (2) electrode size does not affect the relative capacitance vs. (1-$\alpha$) curve, and (3) electrode position is important for stratified flows but it has no effect on annular flows.