• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1999.04a
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• pp.5-5
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• 1999

The Principal deficiency of the existing notion about the sintering-mixtures consists in the fact that almost no attention is focused on the Phenomenon of alloy formation during sintering, its connection with dimensional changes of powder bodies, and no correct ideas on the driving force for the sintering process in the stage of establishing chemical equilibrium in a system are available as well. Another disadvantage of the classical sintering theory is an erroneous conception on the dissolution mechanism of solid in liquid. The two-particle model widely used in the literature to describe the sintering phenomenon in solid state disregards the nature of the neighbouring surrounding particles, the presence of pores between them, and the rise of so called arch effect. In this presentation, new basic scientific principles of the driving forces for the sintering process of a two-component powder body, of a diffusion mechanism of the interaction between solid and liquid phases, of stresses and deformation arising in the diffusion zone have been developed. The major driving force for sintering the mixture from components capable of forming solid solutions and intermetallic compounds is attributed to the alloy formation rather than the reduction of the free surface area until the chemical equilibrium is achieved in a system. The lecture considers a multiparticle model of the mixed powder-body and the nature of its volume changes during solid-state and liquid-phase sintering. It explains the discovered S-and V-type concentration dependencies of the change in the compact volume during solid-state sintering. It is supposed in the literature that the dissolution of solid in liquid is realised due to the removal of atoms from the surface of the solid phase into the melt and then their diffusicn transfer from the solid-liquid interface into the bulk of liquid. It has been shown in our experimental studies that the mechanism of the interaction between two components, one of them being liquid, consist in diffusion of the solvent atoms from the liquid into the solid phase until the concentration of solid solutions or an intermetallic compound in the surface layer enables them to pass into the liquid by means of melting. The lecture discusses peculimities of liquid phase formation in systems with intermediate compounds and the role of the liquid phase in bringing about the exothermic effect. At the frist stage of liquid phase sintering the diffusion of atoms from the melt into the solid causes the powder body to grow. At the second stage the diminution of particles in size as a result of their dissolution in the liquid draws their centres closer to each other and makes the compact to shrink Analytical equations were derived to describe quantitatively the porosity and volume changes of compacts as a result of alloy formation during liquid phase sinteIing. Selection criteria for an additive, its concentration and the temperature regime of sintering to control the density the structure of sintered alloys are given.

• Journal of Science Education
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• v.36 no.1
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• pp.84-93
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• 2012

We have studied possibilities of Peer Instruction(PI) to train in-service science teachers in elementary and middle schools through both degree of conceptual changes and investigating responses to questionaries. 169 teachers were attended and the subject for training was about light propagation to teach scientific conception about a pin hole camera. 6 conceptests were developed. Degree of conceptual changes was analyzed from results obtained from 24 elementary and 32 middle school teachers among them. On the other hand, answers to questionaries were obtained from 135. Relatively high gain near to about 0.7 in conceptual changes was obtained even though their initial levels were quite low. Interesting point is that elementary teachers have higher initial level and larger gain than middle school teachers. Teachers have very much enjoyed and showed strong support to PI for helping conceptual change, and willing to use PI to their own class. Also they conceived dealing concept in teacher training is very important and evaluated PI very positively for teacher training.

• Journal of The Korean Association For Science Education
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• v.25 no.2
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• pp.88-97
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• 2005

The purpose of this study was to investigate explanations of science textbooks and science teachers' conceptions related to freezing point depression phenomenon. Seven kinds of middle school science textbooks and five kinds of high school chemistryII textbooks were analyzed for the purpose. The teachers' conceptions were searched by a questionnaire developed in this study. The subjects were 146 science teachers. The explanation types of science textbooks were divided into two; 'Description of the phenomenon' and 'Vapor pressure lowering'. The explanations in most of middle school science textbooks and high school chemistryII textbooks belong to 'Description of the phenomenon' and there was no explanation of the reason. The graphs related to depression of freezing point were diverse, too. Most of the science teachers also did not have scientific conception. The percentage of the teachers who thought that the cause of freezing point depression was blocking of solute in solution was high. But the teacher could not find meaningful relation the 'Blocking of solute' explanation represented for elevation of boiling point with depression of freezing point. It is insisted that entropy concept is need to explain depression of freezing point phenomenon in this study.

• Journal of the Korean Chemical Society
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• v.50 no.4
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• pp.328-337
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• 2006

purpose of this study was to find out problems in experiments for electrolysis of an aqueous CuCl2 solution in high school science textbooks and to suggest an improved experiment considering students' capability of experimenting and laboratory safety in high schools. For this study, the experiments for electrolysis of an aqueous CuCl2 solution presented in 11 high school science textbooks were classified by their experimental methods. After high school chemistry teachers performed the experiments as presented in the high school science textbooks, an analysis was performed on problems of the experiments, and an improved experiment was devised. According to the results of this study, in the experiments for electrolysis of an aqueous CuCl2 solution using a U type tube and a U type tube with branch, reaction velocity of the electrolysis was slow, therefore, a side reaction was generated. In the experiment using a beaker, reaction of each electrode could not be observed separately. And in the experiment using an electrolysis instrument, it was difficult to identify property of the reaction product. In the improved experiment using a reaction vessel of ㅂshape, reaction velocity of the electrolysis was fast, reaction of each electrode could be observed separately, and the side reaction decreased. From these results, it was suggested that the improved experiment would help high school students understand scientific conception regarding electrolysis.

• Archives of design research
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• v.18 no.3 s.61
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• pp.15-24
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• 2005

There is a large waste of time, money, and production through the infelicitous product design process in small and medium enterprises. They don't possess enough career-manpower with respect to design. Especially, the objective and scientific approach process isn't presented very well on the 'establishment concept' of the embodiment phase or 'Sketch and Rendering' of the development phase which are the most important design processes. So, this research is applied to the conception of the AHP method. It uses the basic concept of relativity to decrease risk from the calculational quantity data, and supplement the decision making phase. Generally, human beings can conclude by relative judgement which is more influenceable than absolute judgement. So we must use the relative comparison concept rather than the comparison of two items with variable sketches based on characteristics of human beings. Thus, efficiency judgement is dependent on design sketch comparisons which help the consistency progress of variable alternative plans. We can decrease risk when we chose the final design and increase efficiency of the design decision making. That is now a perfect selection of each alternative's ranking and sensitive design result but this research will provide consistency criterion on filtering and lead to variable design alternatives. The significance of this research is the efficiency method that overcomes differences of character and sensitivity on many phases of the process. Finally, this research proposes a new ideal process that where applied improves quality and evidence of propriety through comparison to existing methods result in method application research for improvement quality.

• Communications of Mathematical Education
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• v.23 no.3
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• pp.643-682
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• 2009

There is no doubt that the national competitiveness, in 21st century, definitely depends on how effectively it has been producing high-qualify human resources. It is inevitable that we are required to produce outstanding people who are going to make the use of highly developed scientific technology. Every country has already set to concentrate their all efforts in cultivating competitive human resources, enabling it to strengthen its national competitiveness. We Korea, in order to keep up with it, have arranged legal and systematic basis and are putting spurs to producing competent human resources under the 영재교육진흥법 및 시행령, which took effect from March, 2002. With the lack of experience and short history of Gifted Education, however, it is true that we still have many problems in promoting it in reality, We are asked to improve it by finding out what problems we have in whole area of Gifted Education, such as defining conception, choosing target students, structuring system and managing students afterwards. Therefore, this study, especially focusing on Math of Gifted Education is to investigate the present situation of Gifted Education and to examine what we should do for administering Gifted Education in effective ways.

• Journal of Science and Technology Studies
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• v.15 no.2
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• pp.229-262
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• 2015

Toxic tort cases have increased dramatically since the 1970s, as large technological systems, such as nuclear power plants and chemical factories, or mass-produced, high-tech products, had exposed citizens and consumers to dangerous substances. It was, however, difficult to establish causal connection between exposure and the alleged harms in many of the environmental, pollution, and product liability cases under the framework of tort law conception of causation and responsibility. Science and law was called upon to resolve such 'late modern' legal cases where true causes are hard to find, where no single explanatory factor is sufficient for explaining diseases like cancer. This article examines how plaintiffs in the Korean tobacco litigation mobilized such late modern tools in science and law, such as epidemiology and the allocation of the burden of proof, in the context of the global circulation of science and law. It further shows how a set of the scientific theories and legal arguments developed in order to cope with late modern risk played a central role in establishing a causation between smoking and cancer in 2011. This article suggests that STS scholars can fruitfully examine the interaction between science and law as a way to understand and engage with social and legal issues engendered by late modern risk.

• Journal of The Korean Association For Science Education
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• v.27 no.5
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• pp.404-411
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• 2007

The purpose of this study was to examine the types of explanation about different experimental data on students' preconceptions on physical experiment. 45 students were selected from P University by examining their pre-test. The subjects had a scientific conception about a simple pendulum's period of movement, and expected that there was no change in the movement even when the mass of water increased in the can. The students were presented data about pendulum movement inside a can. They recorded this in a blank table and drew a graph about the movement of the pendulum. The responses of students were tested by presenting written anomalous experimental data. Students' recognition, trust about the anomalous data, cognitive conflict, belief change about their preconceptions were examined with written tests also. To measure students' cognitive conflict levels, CCLT (Cognitive Conflict Levels Test) developed in a previous study was used. Some students responded based on preconceptions and regarded the data as manufactured data or experimental error. The students who recognized the anomaly in the situation showed higher cognitive conflict levels than those who didn't recognize the anomaly in the situation. The students who changed their beliefs about preconceptions recognized the data as anomalous situations and showed high cognitive conflict levels than those who didn't abandon their preconceptions. The students who have unchanged beliefs about their preconceptions regarded the data as experimental error.

• Journal of The Korean Association For Science Education
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• v.29 no.6
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• pp.712-729
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• 2009

This study aims to research high school students' misconception of botanic photosynthesis and respiration, and as the measure of rectifying the misconception, to develop the teaching program based on Driver's conceptual change model, applying it to classes and observing the effect. Selected as the research subject was sixty-six students in 1st year of a highschool located in Busan who had chosen Biology Learning as discretionary subject, with their conceptual level on botanic photosynthesis and respiration researched through tests in drawing and descriptive writing. As a consequence of applying drawing as a way of classifying the levels of students' misconception on photosynthesis and respiration, many students' drawings included their misconception caused by textbooks or scientists, but after application of Driver's conceptual change model, they drew scientific drawings including the fundamental factors of botanic photosynthesis and respiration such as light, carbon dioxide, water, glucose, oxygen, leaf, chloroplast, mitochondria, stoma, and energy. Likewise, as a result of the descriptive writing test implemented for researching the students' conception on the various aspects of botanic photosynthesis and respiration, many students in the pretest showed misconception on the point of time and location at which botanic photosynthesis and respiration occur, botanic nutrient, the role of a leaf in photosynthesis, and the relation between botanic photosynthesis and respiration, but after teaching based on Driver's conceptual change model, their misconceptions on photosynthesis and respiration were rectified to a high degree.

• Hwankyungkyoyuk
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• v.18 no.3 s.28
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• pp.59-74
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• 2005

We can't deny Korean EE has basically developed on the basis of Environmental Possibilism (Environmental management or Reformism) in lots of aspects. I would show three representative proofs here, the first, the philosophy of Korean EE has been mainly focused on dichotomy of human-techno centrism and eco-centrism with no considering other alternative environmentalism since 4th Formal Curriculum, 1981. The second, simultaneously, the concept of EE has not distinguished from it of Science education. (Furthermore, unfortunately some says EE has been a part of Science education, although there should be many differences on its contextual aspect.) And the third one is that the limit of possibilism which market economists have worried, has scarcely mentioned in various kinds of EE-related teaching materials. Possibilism is basically likely to be accompanied by science and economics-oriented approach, and in this aspect this dichotomy, human-techno centrism and eco-centrism, has come from perspectives of Economical development process and over-addicted belief to Science. So it is enough to say that Korean EE has basically developed with biased to Environmental possibilism, in other words, biased to preference to it. And I'll critically focus on these two axes of possibilism, Science and Economics and its dichotomy. Of course, we should accept there are so many same parts in its contents between EE and Science, but we should know its contextual differences for triangular position of environmentalism suitable to EE and also overcome science-dependant approach to EE. Although science-dependant approach to EE and dichotomy could provide some tools for clearing up the causes of environmental problem, especially always it has insisted fundamental causes of environmental problem originated in human faults and over-use of eco-source or over-economic development, but now it is old-fashioned discourse, furthermore it come to have unavoidable limits in the debates of problem-solving mechanism to environmental problems. The paramount important thing is to supply the ways or thoughtful mechanism for solving or coordinating the Environmental problems, not just searching for cause of it. But scientific approach and its dichotomy based on possibilism have continuously born cause & effect in EE-related discourse. So there are so much needs to transfer from continuous bearing of cause & effect to constructive alternatives at least in environmentalism of EE. Traditionally, dichotomical division in EE Environmentalism, human-techno centrism and eco-centrism, couldn't have Provided any answers to our real society, it just gives us only cause & effects of Environmental problems. And also we can't find the description on the limits of capitalism market approach to Environmental problems especially in Korean EE text books, other teaching materials and its teaching-learning process, although market approach economist has been proved its fault beyond its functional merits as Environmental management tools. So we should introduce other alternative Environmental philosophy instead of Possibilism such as eco-socialism insisted by Schmacher M. and Boochin etc, or marxist-environmentalism for relative and comparative views to market-thought such as commodification. In this aspect we need to accept Oriental philosophy based on moderation(中庸) as new another alternatives with the reflection that we have recognized monism as representative Oriental philosophical environmentalism. Fundamentally monism has done its role with providing relative concepts to Dichotomy Enlightenment, but we can't say it has been core concept for understanding of oriental environmentalism, and we can't distinguish monism from oriental philosophy itself, just because oriental thought itself was basically monism. So conceptual difference should be recognized between EE and Science education in teaching-learning process on the basis of life-philosophy(Philosophie des Lebens) from epistemology. For this transformation, we should introduce existentialism in Science education, in other words, only existential Science education based on phenomenology or interpretivism can be EE. And simultaneously we need some ways for overcoming of scientific foundationalism which has been tradition making science not stand on existentialism, formulating and featuring of almost all of natural things and its phenomenon from after enlightenment in western world, but it has malfunctioned in fixing conception of science just into essentialism itself. And we also introduce integrated approach to science and society for EE like STS. Those are ways for overcoming of Environmental possibilism in EE.