• Journal of Power System Engineering
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• v.18 no.3
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• pp.66-72
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• 2014

The local heat transfer and pressure drop of developed turbulent flows in the smooth convergent/divergent channels with rectangular and square cross-sectional areas along the axial distance have been investigated experimentally. The measurement was conducted within the range of Reynolds numbers from 15,000 to 89,000. The channel hydraulic diameter ratios of 0.67 and 1.49 in the rectangular channel with 2 inclined walls and the ratios 0.75 and 1.33 in the square channel with 4 inclined walls are considered. The comparison showed that among the four channels the square divergent channel has the highest thermal performance at the identical mass flow rate, at the identical pumping power, and at the static pressure drop.

• Journal of Korean Elementary Science Education
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• v.26 no.5
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• pp.551-557
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• 2007

The purpose of this study was to examine the questions in the 'Matter' units of elementary science textbooks under the 7th curriculum. For the analysis, a total of 338 questions were extracted from 15 units. Six criteria (recalling, recognizing, predictive, applied, divergent, and evaluative question) were reconstructed for textbook question analysis based on Blosser(1973)'s question category system for science. The results were as follows. First, there were more closed (recalling, recognizing, predictive, or applied) questions (72.2%) than open (divergent or evaluative) questions (27.8%) in elementary science textbooks. Second, cognitive-memory (recalling or recognizing) question type was the most frequently asked in all grade levels. Open (divergent or evaluative) questions increased according to grade level whereas convergent (predictive or applied) questions decreased. Third, question types were applied based on the characteristics of each unit rather than on children's developmental characteristics. Educational implications were discussed based on the results.

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1873-1878
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• 2012

Polyamides have great potentials for diverse applications and the present production of their monomers mostly relies on resources from fossil fuel. Starting from undecylenic acid, a natural resource, we have developed both divergent and efficient processes for $C_{10}$, $C_{11}$ and $C_{12}$ ${\omega}$-amino acid and ${\alpha},{\omega}$-dicarboxylic acid monomers of the polyamides.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.35-49
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• 2021

This paper presents a direct numerical simulation of turbulent flows over a bump in an open channel to examine the turbulence characteristics near divergent waves emanating from the bump and to investigate the interaction of the turbulences with the divergent waves. To verify the reliability of the simulations, the mean velocity profile and root-mean-square of velocity fluctuations are compared with previous data. The anisotropic invariant maps show that the ratio of the streamwise to spanwise velocity fluctuations plays an important role in characterizing the anisotropic nature of the separated shear layer behind the bump in the vicinity of the free surface. The vortex identification discloses a large-scale streamwise vortical structure from the mean velocity field and a cluster of small coherent structures from the instantaneous velocity field, which are responsible for the anisotropic characteristics of the turbulence beneath the free surface.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06a
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• pp.350-351
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• 2011

In this paper we study the impact of heterogeneous round trip times on multipath TCP (MPTCP) performance via analysis the fluid model and simulation. Using parameter 'a' in MPTCP can alleviate poor performance due to divergent RTTs between paths. Moreover, divergent RTIs in MPTCP can affect response to changes in the network conditions.

• Journal of Hydrospace Technology
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• v.2 no.1
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• pp.10-17
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• 1996

If a point impulse travels over free surface of water of finite depth, surface waves consist of divergent waves. The crestlines of those divergent waves are short and end on the cusp line if the impulse travels at a subcritical speed. But the crestlines become infinitely long and there are no cusps if the impulse travels at a supercritical speed.

• Journal of Power System Engineering
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• v.21 no.5
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• pp.35-40
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• 2017

The effects of the different rib geometries such as V-shaped continuous (case A), parallel broken (case B), and V-shaped broken (case C) ribs on the heat transfer and pressure drops in a divergent channel with $45^{\circ}$ inclined ribs on one wall or two walls are checked out. The top and bottom walls are adiabatic; two side walls are uniformly heated in the divergent rectangular channel. The tested Reynolds numbers are ranged from 22,000 to 75,000. The channel with two opposite walls inclined only has the length of test section of 1 m and the channel divergence ratio of $D_{ho}/D_{hi}=1.49$, corresponding to $1.43^{\circ}$ inclined walls. The results show in the identical pumping power that the V-shaped continuous rib (case A) with two ribbed walls is the greatest, but the parallel broken rib (case B) with one ribbed wall is the worst in the thermal performance.

• School Mathematics
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• v.15 no.4
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• pp.701-721
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• 2013

In this study, I set the 5th grade children mathematically gifted in elementary school to pose freely the creative and difficult mathematical problems by using their knowledges and experiences they have learned till now. I wanted to find out that the math brains in elementary school 5th grade could posed mathematical problems to a certain levels and by the various and divergent thinking activities. Analyzing the mathematical problems of the mathematically gifted 5th grade children posed, I found out the math brains in 5th grade can create various and refined problems mathematically and also they did effort to make the mathematically good problems for various regions in curriculum. As these results, I could conclude that they have had the various and divergent thinking activities in posing those problems. It is a large goal for the children to bring up the creativities by the learning mathematics in the 2009 refined elementary mathematics curriculum. I emphasize that it is very important to learn and teach the mathematical problem posing to rear the various and divergent thinking powers in the school mathematics.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.5
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• pp.346-354
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• 2002

The present study is to investigate the propagation characteristics of the impulse waves discharged from the exit of the convergent and divergent pipes. An experiment is carried out using a shock tube with an open end and is compared to the computation of the axisymmetric, compressible, unsteady Euler equations, which are solved by the second-order total variation diminishing (TVD) scheme. For the computational work, several initial compression waves are assumed inside the pipe so that those are the same to the experimental ones of the shock tube. The results show that the peak pressures of the impulse waves discharged from the exit of convergent and divergent pipes decrease with an increase in the wavelength of the initial compression wave. All of the impulse waves have a strong directivity toward the pipe axis, regardless of the exit type of the pipe employed. The impulse waves discharged from the divergent pipe are stronger than those from the straight pipe, while the impulse waves of the convergent pipe are weaker than those from the straight pipe. It is found that the convergent pipe can play a role of a passive control to reduce the peak pressure of the impulse wave. The present computations represent the experimented impulse waves with a good accuracy.

• Journal of Elementary Mathematics Education in Korea
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• v.10 no.2
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• pp.171-194
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• 2006

As it is not long since the gifted education was implemented in elementary school, it is necessary to accumulate the practical studies on the mathematically gifted education. This paper focused on enhancing creativity by providing the various and divergent thinking activities for mathematically gifted students. For this purpose, I prepared two mathematics problems, and , and let the mathematically gifted 5th grade students solve them. After that, I investigated to analyse their reactions in detail and tried to find the methods for assessing their divergent products. Finally, I found that they could pose various and meaningful calculating equations and also identify the various relations between two numbers. I expect that accumulating these kinds of practical studies will contribute to the developments of gifted education, in particular, instructions, assessments, and curriculum developments for the mathematically gifted students in elementary schools.