• 한국과학교육학회지
• /
• 제28권3호
• /
• pp.187-196
• /
• 2008

In this study, a survey was conducted of students in grades 7 through 12, student teachers enrolled in their senior year at teachers' colleges, and science teachers. Subjects were surveyed on their conceptions of phenomenon related with dissolution, saturation, and extraction. The models and analogies used by student teachers and science teachers to explain dissolution were sought. The highest percentage of students thought of dissolution as a phenomenon in which particles broke into the spaces between other particles. The models or analogies used by the highest percentage of science teachers were similar. They generally conceived of dissolution phenomenon through what we call the 'space conception'. A conception of dissolution phenomenon as 'hydration through attraction of solvent and solute' was held by more student teachers than science teachers; there were some differences, however, according to their academic background. The percentage of teachers professing this view decreased when they attempted to explain the process of extraction of matter in a solution after other matter had dissolved or after the solution was cooled, indicating that the 'hydration' conception was not firmly established in the student teachers' cognition. Therefore, it can be inferred that the conceptions of dissolution as 'hydration' were transformed into the conceptions of dissolution as 'space' after teaching dissolution phenomenon as practicing teachers. This finding should be considered in teacher-training courses.

• 한국초등과학교육학회지:초등과학교육
• /
• 제22권2호
• /
• pp.138-148
• /
• 2003

This study was to analyze how elementary school science textbooks explain dissolution and to examine the patterns of elementary school teachers' conceptions on dissolution and the teaching practices on dissolution of elementary school teachers. According to the result of the textbook analysis, the textbooks based on the 7th curriculum didn't explain dissolution very differently from those based on the 6th curriculum. The contents dealing with dissolution in the textbooks of 7th curriculum became difficult gradually as the year went up, but the connected organization of the contents made students learn it easily. For example, in order to learn dissolution introduced first in the 3rd year 2nd semester textbook, students would tell soluble substance in water from insoluble substance in water as they put powdered substance in water. In the 5th year 1st semester textbook students were supposed to acquire the knowledge related to dissolution through the designed activities such as comparing solubility produced by different solvents and defining a solvent, a solute, dissolution, and a solution. In addition, teachers' guide for 5th year 1st semester textbook elucidated the principle of dissolution using attraction concept that was scientific. The result of the survey on teachers showed that 90% of elementary school teachers understood the dissolution of salt in water just as millet particles' filling the space between bean particles and they responded that they demonstrated millet particles' filling the space between been particles when they taught the dissolution of salt in water. When it comes to teachers who had the right idea on dissolution as the attraction conception, understanding was one thing and teaching was another, because they often instructed dissolution as the space conception in the real teaching.

• 대한화학회지
• /
• 제48권4호
• /
• pp.399-413
• /
• 2004

이 연구에서는 용해와 관련된 현상에 대해서 초등학교 학생에서부터 대학생에 이르기까지 학교급에 따라 학생들이 가지는 개념유형을 알아보고, 초${\cdot}$중등학교 교사들의 용해 현상에 대한 지도 실태를 알아보았다. 연구 결과, 초등학생 때 형성된 구멍 개념에 의한 용해 현상의 이해가 고등학생 때까지 유지되고 있었으며, 인력 개념에 의해 용해 현상을 학습하는 시기인 고등학교 2, 3학년과 대학생들은 인력 개념으로 용해 현상을 이해하는 비율이 상대적으로 높게 나타났다. 그러나 용해 현상을 설명할 때는 초등학생에서부터 대학생에 이르기까지 많은 학생들이 인력 개념보다는 구멍 개념을 선호하는 것으로 나타났고, 개념의 이해와 설명에 커다란 차이를 나타냄으로써 학생들의 용해 현상에 대한 이해 정도가 전반적으로 낮음을 알 수 있었다. 교사들의 설문 응답 분석 결과, 초등학교 교사의 90% 정도가 소금이 물에 녹는 현상을 콩 사이로 좁쌀이 들어가는 것과 같은 현상으로 이해하고 있었으며, 실제 학생들에게 소금이 물에 녹는 현상을 콩 사이로 좁쌀이 들어가는 모형을 이용하여 지도한다고 응답하였다. 중등학교 교사들 역시 약 절반 정도는 용해 현상을 구멍 개념으로 이해하고 있었으며, 인력 개념으로 바르게 이해하고 있는 교사는 20% 정도에 지나지 않았다. 또한, 인력 개념으로 이해하고 있는 교사들도 실제 학생들을 지도할 때는 구멍 개념으로 설명하는 경우가 많아 교사들의 개념 이해와 지도에는 차이가 있음을 알 수 있었다.

• 대한화학회지
• /
• 제52권1호
• /
• pp.73-83
• /
• 2008

이 연구의 목적은 고등학생들의 용해·확산과 관련된 혼합현상에 대한 개념 유형을 알아보고자 하는 것이다. 연구대상은 화학 I 과목을 수강하는 고등학교 2학년 학생 108명과 화학 II 과목을 수강하는 고등학교 3학년 학생 29명이다. 연구 결과, 많은 학생들이 분필이 무극성 물질이기 때문에 물에 섞이지 않는다는 대안 적 개념을 가지고 있었다. 사염화탄소가 물에 섞이지 않는 현상에 대해서 대부분의 학생들이 인력의 개념으로 이해하였으나, 밀도 차이와 같은 물질의 특성의 차이로 이해하는 유형 또한 많았다. 물과 에탄올이 한없이 섞 이는 현상은 많은 학생들이 인력 개념으로 이해하였다. 대부분 학생들은 수성 잉크와 물이 섞이는 현상을 섞 이는 이유에 대해서는 알지 못한 채 단지 퍼져나가는 현상 자체로만 받아들이고 있었다. 요오드가 사염화탄소 에 섞이는 현상은 구멍이론이나 인력 개념으로 이해하였다. 이러한 용해·확산과 관련된 혼합현상에 대한 다 양한 대안적 개념은 엔트로피 개념의 부족으로 인한 것이다. 따라서 학생들이 이러한 현상을 제대로 이해하도 록 과학 교과서의 서술 방식이 바뀔 필요가 있다.

• 한국초등과학교육학회지:초등과학교육
• /
• 제29권4호
• /
• pp.474-483
• /
• 2010

In this study, we investigated preservice elementary school teachers' awareness of students' misconceptions about several science topics, and the variables influencing their awareness. Seniors (N=106) from an university of education were asked to predict elementary school students' misconceptions on science topics such as phase changes and dissolution. Their conceptions about teaching and learning were also measured. The results indicated that the preservice teachers' predictions about the kinds and/or the ratios of students' misconceptions were different from those reported in previous studies. The low level preservice teachers in terms of the degrees of possessing traditional conception about teaching and learning predicted more students' common misconceptions. The degrees of preservice teachers' constructivist conception about teaching and learning and their major, however, did not significantly influence the numbers of common misconceptions predicted.

• 대한화학회지
• /
• 제57권4호
• /
• pp.507-514
• /
• 2013

이 연구에서는 시각장애를 가진 초등학생의 용해 개념 특성을 조사하였다. 서울시 소재 시각장애 초등학교 5학년 학생 4명(3명은 전맹, 1명은 저시력)을 대상으로 용해 현상, 용액의 균일성, 용해 시 질량의 보존, 그리고 용해 시 부피의 변화에 대하여 반구조화된 인터뷰를 실시하였다. 모든 인터뷰 상황은 녹화되었고 그 자료를 전사한 뒤 분석하였다. 인터뷰를 분석한 결과, 시각장애 학생들은 용해 현상, 용해의 균일성, 용해 시 질량의 보존에 대해서는 잘 알고 있었지만, 용해 시 부피변화에 대해서는 제대로 설명하지 못하였다. 전반적으로는 같은 학년의 일반 학생과 비슷한 양상을 보였지만, 용해의 균일성에 대해서는 오히려 더 바르게 알고 있었다. 그러나 이들의 설명 수준은 현상적 경험에 기초한 피상적 수준에 불과했다. 일부 시각장애 학생은 입자 수준의 설명을 시도하기도 하였다. 이러한 결과에 기초하여 교육학적 함의를 논의하였다.

• 한국실내디자인학회논문집
• /
• 제40호
• /
• pp.68-75
• /
• 2003

The purpose of this study is to find out the expression style of space in Rietveld's early works in comparison with Mondrian's paintings. Through investigating the development of their works and analyzing the composition and disposition type of elements such as point, line, plane, color in the selected works, we can draw the following conclusions. .First, Rietveld pursues the dissolution of traditional volume and the de-composition of elements as Mondrian does. Second, the painterly property of plane is emphasized by the projection of separately floating elements on the picture plane. Third, the separating the layer of lines from the layer of planes and the re-combination of these two layers present the superimpositional image of three-dimensional objects. This leads into new conception of architectural space and develops the transparency and the extension of plan in modem architecture.

• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 1999년도 춘계학술대회 및 발표대회 강연 및 발표논문 초록집
• /
• pp.5-5
• /
• 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.

• 한국언론정보학보
• /
• 제16권
• /
• pp.168-206
• /
• 2001

This study attempts to examine the relationships between the major market-based media and the government after closing military regime era, 1961-1987. After the military regime was collapsed, while the mass media in Korea obtained independence and autonomy from government, they have been confronted with the terrible competition not so much comparatively as before. The watchdog role in the traditional liberalism, which is regarded as normative relationship between the media and the government would be transformed in accordance with the market condition and the maturity of democracy. Thus, the watchdog metaphor has been variously deviated in rower-centered society; lap dog, guard dog, attack dog. liberalists argue that the primary democratic role of the media is to art as a public watchdog overseeing the state. Social democrats, however, criticize them as simplistic conception which could be only applied to the government. They argue that the media should be seen as a source of redress against the abuse of all forms of power over others; the home, the economy, and the civil society. The lap dog view is that the media is overwhelmingly dependent on the established power structure contrary to the watchdog. While the guard dog perspective is a means to preserve the power structure alarming with playing 'conflict role', the attack do8 aims to the private interest of the media in intruding into the politics. The attack dog perspective by T. Patterson could be composed of the interpretive style of report, the game schema report over the policy schema in the election, and the negativism against politics and government. The market-dominant press has been likely to transform from lap-guard dog into attack-guard dog. In Roh Tae Woo government(1988-1992), while the press was a lessened lap-guard dog before three parties merger in 1990, after merger the press had been transformed as the reinforced lap-guard dog because this merger entailed joint, party-to-party negotiations, and the formation of the new party preceded by dissolution of the ruling blot. In the early stage of Kim Young Sam government(1993-1997), the press has kept in pace with the reform movement drive-forced by the government. However, the press withdrew the support of Kim's reform in reaching the level of threat to ruling bloc. The press coalesced only circumstantially with government and was interested in preserving some margin of independence. The failure of Kim's reform proved the political muscle of the press in post-autho-ritarianism. In the middle stage of Kim Dae Jung government (1998-) that resulted in the shift of power structure as once-opposition party leader, the stress has been a manifested attack-guard dog owing to the anti-cold war policy, the realignment policy of power, and the minority-base of Kim's government. The press has endeavored to hold political communication within limits relatively less threatening to the established order.