• Journal of the Korea Computer Industry Society
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• v.2 no.10
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• pp.1301-1308
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• 2001

In this paper, some interesting aspects of Grzegorczyk classes $\xi\sum{n}$, n$\geq$0 & $\sum$= { 1, 2 } of word-theoretic primitive recursive functions are observed including the classes of its corresponding predicates ($\xi\sum{n}$)* In particular, the small classes $\xi\sum{n}$($n\leq2$) are very incomparable to the corresponding small classes $\xi\sum{n}$ where $\xi\sum{n}$ is the number-theoretic Grzegorczyk classes. As one of some interesting aspects of the small classes, we show that the equivalence problem in $\xi\sum{0}$is undecidable.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.10a
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• pp.225-228
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• 2004

The generalized knapsack problem, or gknap is the combinatorial optimization problem of optimizing a nonnegative linear functional over the integral hull of the intersection of a polynomially separable 0 - 1 polytope and a knapsack constraint. Among many potential applications, the knapsack, the restricted shortest path, and the restricted spanning tree problem are such examples. We prove via the ellipsoid method the equivalence between the fully polynomial approximability and a certain pseudo-polynomial separability of the gknap polytope.

• The Mathematical Education
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• v.57 no.2
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• pp.179-196
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• 2018

The purpose of this study was to investigate the measurement equivalence and to suggest application ways in teaching aptitude and personality test results for pre-service mathematics teachers between a graduate school of education and a college of education. This study analyzed the scores of the teaching aptitude and personality test of 36 pre-service mathematics teachers enrolled in a graduate school of education and 111 pre-service mathematics teachers in a college of education by performing a multivariate generalizability analysis. The main results were as follows. First, graduate's pre-service mathematics teachers had a higher level of teaching aptitude and personality than that of college's pre-service mathematics teachers based on the total scores. In addition, graduate's pre-service mathematics teachers had higher levels of teaching aptitude and personality than those of college's pre-service mathematics teachers except for a creativity application domain based on the sub-domain scores. Second, cognitive domains were measured more precisely but affective domains were measured less precisely for graduate's pre-service mathematics teachers than for college's pre-service mathematics teachers. Third, regardless of school levels, Cronbach's ${\alpha}$ values, which might be overestimated by applying the classical test theory, were higher than dependability coefficients. Fourth, this study showed a somewhat negative result in ensuring the measurement equivalence for a problem solving exploration domain. However, regardless of school levels, this study indicated that the overall measurement was generally reliable on composite scores. Based on these results, it was confirmed that multivariate generalizability methodologies' approach can be useful for exploring the measurement equivalence issues. Finally, this study suggests how to utilize the results of the test, how to apply a multivariate generalizability analysis for detecting the measurement equivalence, and how to develop future research based on limitations.

• Nuclear Engineering and Technology
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• v.16 no.4
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• pp.202-216
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• 1984

The success of coarse-mesh nodal solution methods provides strong motivation for finding homogenized parameters which, when used in global nodal calculation, will reproduce exactly all average nodal reaction rates for large nodes. Two approximate theories for finding these ideal parameters, namely, simplified equivalence theory and approximate node equivalence theory, are described herein and then applied to the PWR benchmark problem. Nodal code, ANM, is used for the global calculation as well as for the homogenization calculation. From the comparative analysis, it is recommended that homogenization be carried out only for the unique type of fuel assemblies and for core boundary color-sets. The use of approximate homogenized cross-sections and approximate discontinuity factors predicts nodal powers with maximum error of 0.8% and criticality within 0.1% error relative to the fine-mesh KIDD calculations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.8 s.239
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• pp.963-970
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• 2005

The combustion instability of turbulent flames is the most important problem of the gas turbine combustor. Thus improved understanding of mechanisms of combustion instability is necessary for the design and operation of gas turbine combustors. In this study, the cause of the combustion instability in a rearward-step dump combustor was investigated with respect to the fuel flow modulation; choked fuel flow, unchoked fuel flow and fully premixed mixture flow. We observed various types of combustion instabilities with respect to the change of equivalence ratio, fuel flow conditions and fuel injection location. Particularly in the unchoked fuel flow condition, it was found that the oscillation time of combustion instability is strongly related to the convection time of the fuel and that the pressure fluctuation in a lab-scale combustor is highly related to the vortex and the equivalence ratio fluctuations due to fuel flow modulation and unmixedness of the fuel and air.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.7
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• pp.1702-1708
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• 1995

Owing to the serious problem of hydrocarbon fuel such as environmental pollution, the development of alternative fuel is very urgent. To adopt hydrogen to the internal combustion engine, a solenoid-drive type in-cylinder injection system was constructed. The injection system was installed to the single cylinder research engine, and the engine performance and the emission of citric oxide were tested upon the fuel-air equivalence ratio and the spark timing. In the case of in-cylinder injection system, hydrogen is injected after the intake valve is close, so it is possible to operate the engine without the back fire and the fall of its volumetric efficiency. In the region of the fuel-air equivalence ratio below 0.5, hydrogen and air aren't well mixed and the thermal efficiency is lowered, so the nozzle should be designed to inject hydrogen uniformly into the combustion chamber. In the region of the fuel-air equivalence ratio above 0.7,the fuel-air mixture burns very fast and the amount of citric oxide emission increases rapidly, so the spark timing should be retarded as compared with MBT.

• Journal of the Korean Society of Combustion
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• v.14 no.4
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• pp.7-16
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• 2009

Porous metal plates (Metal fiber, muti-hole metal plate) using mainly in surface burner are known to have a corrosion and durability problem under high temperature condition. In this study, premixed flat flame with perforated ceramic tile of more durable cordierite material was examined with respect to combustion stability and emission. The flat premixed ceramic burner consists of perforated ceramic tile and various type of baffle plates to form stable surface flame. The results show that most stable flat flame is generated using baffle plate with open ratio of 0.193. In downward flat flame mode which is widely used in condensing boiler, CO is measured below 50ppm from equivalence ratio 0.755 to 0.765 and $NO_X$ is measured below 12ppm from equivalence ratio 0.75 to 0.79. It is also found that the range of blue flame in flame stability curve becomes wider with increasing heat capacity.

• Honam Mathematical Journal
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• v.31 no.2
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• pp.247-258
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• 2009

This paper introduces new mixed vector FQ-implicit variational inequality problems and corresponding mixed vector FQ-implicit complementarity problems for set-valued mappings, and studies the equivalence between them under certain assumptions in Banach spaces. It also derives some new existence theorems of solutions for them with examples under suitable assumptions without monotonicity. This paper generalizes and extends many results in [8, 10, 19-22].

• Journal of applied mathematics & informatics
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• v.29 no.1_2
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• pp.337-349
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• 2011

This paper is concerned with deriving necessary and sufficient optimality conditions for a fuzzy linear programming problem. Toward this end, an equivalence between fuzzy and crisp linear programming problems is established by means of a specific ranking function. Under this setting, a main theorem gives optimality conditions which do not seem to be in conflict with the so-called Karush-Kuhn-Tucker conditions for a crisp linear programming problem.

• The Pure and Applied Mathematics
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• v.19 no.3
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• pp.281-288
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• 2012

In this paper, the author defines a new generalized ${\eta}$, ${\delta}$, ${\alpha}$)-pseudomonotone mapping and considers the equivalence of Stampacchia-type vector variational-like inequality problems and Minty-type vector variational-like inequality problems for generalized (${\eta}$, ${\delta}$, ${\alpha}$)-pseudomonotone mappings in Banach spaces, called the generalized vector Minty's lemma.