• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.12
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• pp.1702-1710
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• 2001

Supersonic coaxial jets are investigated numerically by using the axisymmetric, Wavier-Stokes equations which are solved using a fully implicit finite volume method. Three different kinds of coaxial nozzles are employed to understand the flow physics involved in the supersonic coaxial jets. Two convergent-divergent supersonic nozzles are designed to have the same Mach number 2.0, and used to compare the coaxial jet flows with those discharging from one constant-area nozzle. The impingement angle of the annular jets are varied. The primary pressure ratio is changed in the range from 2.0 to 10.0 and the assistant jet ratio from 1.0 to 3.0. The results obtained show that the fluctuations of the total pressure and Mach number along the jet axis are much higher in the constant-area nozzle than those in the convergent-divergent nozzles, and the constant-area nozzle lead to higher total pressure losses, compared with the convergent-divergent nozzles. The assistant jets from the annular nozzle affect the coaxial jet flows within the distance less than about ten times the nozzle throat diameter, but beyond it the coaxial jet is conical with self-similar velocity profiles. Increasing both the primary jet pressure ratio and the assistant jet pressure ratio produces a longer coaxial jet core.

• Journal of Science and Technology Studies
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• v.12 no.2
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• pp.33-79
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• 2012

This paper first aims to reveal that, in the current trend of 'the participatory turn' in STS, there are divergent positions subtly different from each other, and that the understanding of these divergent positions can be significant to study the differences, similarities and interfaces between the various models of scientific governance discussed in STS and those in risk governance developed by risk studies. Secondly, this paper shows that theoretical differences among STS scholars on scientific governance and public participation goes back to the 1970s and 1980s, during which they first laid down the conceptual basis of STS. All ideas and theories have their own historicity. This article is about the 'historical epistemology' of the participatory turn of STS, and is to seek 'political epistemology' that can become a shared vision of STS.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.3
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• pp.62-69
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• 2014

This paper presents a preliminary study of a convergent divergent nozzle in an afterburning turbofan engine of a supersonic aircraft engine. In order to design a convergent divergent nozzle, cycle model of a low bypass afterburning turbofan engine of which thrust class is 29,000 lbf at a sea level static condition is established. The cycle analysis at the design point is conducted by Gasturb 12 software and one dimensional gas properties at a downstream direction of the turbine are obtained. The dimension and configuration of an model turbofan engine are derived from take-off operation with wet reheat condition. The off-design cycle calculation is conducted at the all flight envelope on the maximum flight Mach number of 2.0 and maximum flight altitude of 15,000 m.

• Journal of Aerospace System Engineering
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• v.12 no.5
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• pp.40-47
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• 2018

The objective of this study is to investigate the turbulence models with compressibility correction for large separation-flow in a supersonic convergent-divergent rectangular nozzle. As turbulence models, Yang and Shih's Low-Re $k-{\varepsilon}$ model, Mener's $k-{\omega}$ SST model and Wilcox's $k-{\omega}$model were evaluated. In order to get a significant compressible effects, Sarkar and Wilcox compressibility correction models were applied to the turbulence models respectively. Also, the simulation results were compared with experimental data. The turbulence model with compressibility correction model improves both of shock position and pressure recovery, but deteriorates the length of Mach disk.

• Journal of Elementary Mathematics Education in Korea
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• v.10 no.1
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• pp.1-19
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• 2006

It is generally accepted that fostering creative thinking is a core in mathematics education and accumulating research products on that topic is really needed. In this study, I hoped to investigate and verify that in mathematics education it was possible to cultivate creative thinking through various and divergent activities, For this purpose, I delat with some illustrations, in which students learned mathematics through the operational activities using teaching tools, problem solving and problem posing activities, and finally they seemed to foster creative mathematical thinking. In conclusion of this paper, I have suggested that in math education those activities should be used to cultivate students' creative thinking in kindergarten or early elementary school. Also I asserted that it is urgently need to store up research products about various materials and methods for those mathematics teaching and learning.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.2
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• pp.94-104
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• 2013

A numerical analysis has been conducted to determine the pitch thrust vectoring characteristics of a two-dimensional convergent divergent exhaust nozzle for supersonic aircraft application. The numerical analysis was done by using Fluent and verified by the experimental test results. Analysis was performed with pitch angle of $0^{\circ}$ and $20^{\circ}$ each at the ambient temperature condition. To see the effect of a ratio of pitch flap length and pitch flap height, the ratio was varied from 0.5 to 2.5. The numerical analysis shows that pitch thrust is changed greatly with pitch flap length. The big difference of the pitch thrust with pitch flap length is due to the shock interactions in the nozzle.

• Journal of The Korean Association For Science Education
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• v.18 no.2
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• pp.149-160
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• 1998

The purpose of this study was to analyze the 6th national secondary science curriculum and classroom practices to collect the basic data for developing secondary science program focusing on creative problem-solving ability. The creative problem-solving ability was conceptualized as an active process of producing new solutions to problems and consisted of five components: general knowledge, domain-specific knowledge, motivation, divergent thinking and critical thinking. The research questions were generated as follows: (1) Whether creative problem-solving elements-domain specific knowledge(declarative knowledge and inquiry methods) were included or not in the 6th secondary science curriculum, textbooks and teacher's guide? If so, how are they represented? (2) Whether the teachers tried to enhance divergent and critical thinking of their students. Through content analyses, observations and interviews, these research questions were answered as follows: (1) Inquiry methods, which are important to develop creative problem-solving abilities in science, were underestimated in comparison with declarative knowledge. In other words. inquiry methods were regarded only as tools to understand the scientific concepts and principles. (2) It was hard to find the situations which teachers provided opportunities for divergent and critical thinking to their students. Based on these results, the followings were recommended: (1) Inquiry methods should be regarded as a goal not as a tool and be used to acquire inquiry methods themselves. (2) Teachers should not stick to the prescribed inquiry methods prescribed in the textbook, but to give opportunities for thinking various kinds of inquiry methods to improve divergent and critical thinking.

• Journal of the Korean Chemical Society
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• v.55 no.2
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• pp.290-303
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• 2011

The purpose of this study was to introduce the practical model on the enhancement of the divergent and convergent thinking skills through inquiry instruction in science class. In this study, the creative thinking skill has been defined by divergent thinking skill as the narrow sense. In the science field, the problem solving thinking skill is just same as the inquiry thinking skill. Also, the problem solving thinking skill has been defined by convergent thinking skill as the critical thinking skill. This new instruction had been used for the college student in the class of general chemistry laboratory for the one semester. The first results had been founded that the students' divergent thinking skill had been increased significantly. Especially, the skills of recognition of problems, the skills of making hypothesis, and the skills of transformation and interpretation of data had been increased significantly. The second results had been founded that the students' convergent thinking skill had been increased significantly. Especially, the skills of making hypothesis, the skills of transformation and interpretation of data, and the skills of making conclusion and generalization had been increased significantly. The third results had been founded that the students' the creative and problem solving thinking skill had been increased significantly. Especially, the rest of all skills exception the skill of control variables had been increased significantly.

• Journal of Gifted/Talented Education
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• v.10 no.2
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• pp.47-69
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• 2000

One of the most controversial issues in contemporary research of creativity, whether a person"s creativity is domain-specific or domain-general, was investigated with 109 second grade children in the present study. The purposes of this study sere to empirically examine (1) the relationships among children's creative performances measured by three product-based assessments (story-telling, collage-making, and math word problems) in three domains, and (2) the relationships between children's general creative thinking sills, measured by two divergent thinking tests, and children's creative performances. The findings of this study support the position that creative ability in young children is rather (but not absolutely0 domain-specific. Children exhibited a range of creative ability across different domains rather than a uniform creative ability in diverse domains, indicating there is considerable intra-individual variation in creative ability by domain. Divergent thinking measures did not have great power in predicting creative performance in at least two of three, if not all, domains assessed in the study. It is implied from the study that it is not possible to reliably predict a child"s creative ability in one domain based on his/her creative ability in other domains or his/her overall divergent thinking ability. Implication of the study in connection with educational practices for gifted children is discussed.

• Journal of The Korean Association For Science Education
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• v.28 no.5
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• pp.482-494
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• 2008

The purpose of this study was to introduce a practical model to enhance creative and critical thinking skills through hypotheses generating activities for students. The 2007 Science National Curricula stresses the need for the enhancement of creative thinking skills for our students. The definition for the creativity in the narrow sense is the divergent thinking skills. The definition of the critical thinking skills is the strong sense of those skills. This model shows the use of the divergent thinking skills and convergent thinking skills together. The divergent thinking skills has been developed by making three alternative explanations about the causal question within a group of students by active discussion. The following procedure includes the selection of the most provable of the three explanations within a group of students also by active discussions. This process needs convergent thinking skills as well as critical thinking skills. This model can be used easily by exchanging from the one explanation about the causal question in any inquiry teaching strategy to three explanations about one. Although the partial modified strategy shows a small difference from any inquiry teaching strategy, but the effect of the enhancement of the creative thinking skills for our students shows significantly better (p<.05). More detailed study will be carried out in the near future.