• Korean Chemical Engineering Research
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• 제59권4호
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• pp.626-631
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• 2021

One of the nonlinear electrokinetic phenomena around ion exchange membrane is electroconvective instability which can be found in various electrokinetic applications such as electrodialysis, electrochemical battery, microfluidic analysis platform, etc. Such instability acts as a positive transport mechanism for the electrodialysis via amplifying mass transport rate. On the other hands, in the electrochemical battery and the microfluidic applications, the instability provokes unwanted mass transport. In this research, to control the electroconvective instability, the onset of the instability was analyzed as a function of confinement effect as well as applied voltage. As a result, we figured out that the dynamic behavior of electroconvective instability transited as a sequence of stable regime - static regime - chaotic regime depending on the applied voltage and confinement effect. Furthermore, stability curves about the dynamic transition were numerically determined as well. Conclusively, the confinement effect on electroconvective instability can be applied for effective means to control the electrokinetic chaos.

• Journal of the Korean Chemical Society
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• 제47권6호
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• pp.645-658
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• 2003

This study was carried out to analyze inquiry area of the chemistry (II) textbooks which were published by the 7th curriculum. The study attempts to analyze the degree to which chemistry (II) textbooks reflected the guidelines of the 7th science curriculum and propose educational suggestions for the inquiry learning. The analysis of the inquiry area was carried out based on the suggested inquiry elements of the 7th science curriculum. Overall, for the analysis of inquiry elements, basic inquiry elements except classifying suggested by the 7th science curriculum were well reflected on the textbooks. However, for the integrated inquiry elements, interpreting data takes almost half of the total integrated inquiry elements. Other integrated inquiry elements except drawing conclusion and transforming data were reflected less than ten percent. Investigation was also reflected less than ten percent of all inquiry activity. And inquiry activities were limited in terms of variety with few projects and no field trip. The main essence of the 7th science curriculum is the emphasis on total inquiry learning through various integrated inquiry elements and inquiry activities for higher grade students. Thus it is suggested that teachers provide inquiry learning which can supplement the textbook.

• Journal of the Korean Chemical Society
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• 제47권5호
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• pp.505-518
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• 2003

A survey has been administered to investigate the adequacy of the chemistry teacher employment examination. The questionnaires were sent to the professors of the fourteen departments of chemistry education all over the nation and the responses were collected from the thirteen departments. From the analyses of the responses, the problems were pointed out and the suggestions were made for the improvement of the examination to recruit excellent chemistry teachers. Reconsideration of the ratio of subject matter education to subject contents, adjustment of format and number of questions, maintaining of proper degree of difficulty and discrimination of items, reconsideration of relevancy to practical education, raising the number of committee for the examination, the reflection of the 7th science curriculum, and opening to the public of the information related to the teacher employment examination were discussed.

• Journal of the Korean Chemical Society
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• 제65권5호
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• pp.370-381
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• 2021

This study compared and analyzed the chemistry curriculum of South Korea and Singapore. The analysis revealed that Korea's achievement standards in the chemistry subject comprised knowledge and skills, whereas Singapore's achievement standards comprised knowledge, skills, values, and attitudes. The scope of knowledge and skills of the Singaporean achievement standards-wherein each element was explicitly presented-were more extensive than that of Korea. The elementary school curriculum in both countries was structured to help students qualitatively understand materials in real life, whereas the middle school content was structured such that students could understand the topic of particles. Additionally, several differences were found in specific content elements; for example, the periodic tables were included only in the Singaporean content, whereas changes in the volume of gas according to temperature and pressure were included only in the Korean content. The Singaporean academic achievement standards, integrating knowledge, skills, values, and attitudes in science curriculum, can be used as a reference for adjusting and restructuring the Korean curriculum.

• Journal of the Korean Chemical Society
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• 제58권5호
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• pp.437-444
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• 2014

The electrochemical corrosion and passivation of Co-RDE in borate buffer solution was studied by Potentiodynamic and electrochemical impedance spectroscopy. The mechanisms of both the active dissolution and passivation of cobalt and the hydrogen evolution in reduction reaction were hypothetically established while utilizing the Tafel slope, the rotation speed of Co-RDE, impedance data and the pH dependence of corrosion potential. Based on the EIS data, an equivalent circuit was suggested. In addition, the electrochemical parameters for specific anodic dissolution regions were carefully measured. An induction loop in Nyquist plot measured at the open-circuit potential was observed in the low frequency, and this could be attributed to the adsorption-desorption behavior in the corrosion process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.163-163
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• 2008

반도체 소자가 고집적화 되고 고속화를 필요로 하게 됨에 따라, 기존에 사용되었던 알루미늄이나 텅스텐보다 낮은 전기저항, 높은 electro-migration resistance으로 미세한 금속배선 처리가 가능한 Cu가 주목받게 되었다. 하지만 과잉 디싱 현상과 에로젼을 유도하여 메탈라인 브리징과 단락을 초래할 있고 Cu의 단락인 islands를 남김으로서 표면 결함을 제거하는데 효과적이지 못다는 단점을 가지고 있었다. 특히 평탄화 공정시 높은 압력으로 인하여 Cu막의 하부인 ILD막의 다공성의 low-k 물질의 손상을 초래 할 수 있는 문제점을 해결하기 위하여 기존의 CMP에 전기화학을 결합시킴으로서 낮은 하력에서의 Cu 평탄화를 달성 할 수 있는 기존의 CMP 기술에 전기화학을 접목한 새로운 개념의 ECMP (electrochemical-mechanical polishing) 기술이 생겨나게 되었다. 따라서 본 논문에서는 최적화된 ECMP 공정을 위하여 I-V곡선과 CV법을 이용하여 active. passive. trans-passive 영역의 전기화학적 특징을 알아보았고. Cu막의 표면 형상을 알아보기 위해 Scanning Electron Microscopy (SEM) 측정과 Energy Dispersive Spectroscopy (EDS) 분석을 통해 금속 화학적 조성을 조사하였다.

• Journal of the Korean Chemical Society
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• 제48권6호
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• pp.629-637
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• 2004

제7차 교육과정에 따른 중등 과학 교과서 중 화학 영역에 사용된 비유를 분석하였다. 전체 35권의 교과서에서 비유 사용 빈도는 325회로 13쪽마다 평균 1회 사용되었고, 단 한 번만 사용된 비유가 많았다. 유형별로는 기능적 비유, 언어와 그림을 모두 사용한 비유, 추상적 목표물을 구체적 비유물로 설명한 비유, 단순 비유와 부연 비유, 교사 중심 비유, 체계성이 낮은 비유가 많았고, 일상 비유와 작위적 비유가 비슷하게 사용되었다. 교과서 본문 중에 '비유‘라는 용어를 사용한 경우는 적었으며, 제한점에 대한 언급은 거의 없었다. 제6차 교육과정에 따른 과학 교과서에 비하여 쪽 당 비유의 수는 증가하였으나, 표현 방식, 작위성, 학습자 참여성을 제외한 모든 유형에서 비슷한 경향을 나타내었다. 이 결과들에 대한 교육적 시사점을 논의하였다.

• Journal of the Korean Chemical Society
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• 제48권4호
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• pp.414-426
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• 2004

This study analysed inquiry process and activities of the inquiry area in the chemistry field of middle school science textbooks by the inquiry elements based on the 7th science curriculum. The purpose of this study is to grasp a degree of reflecting the 7th science curriculum in the 9th grade science textbooks, and to find out educational implications for the various inquiry learning. Overall, for the analysis of inquiry elements, basic inquiry elements except classification were well reflected on the middle school science textbooks in 9th grade. However, for the integrated inquiry elements, interpreting data occupies almost half of them. This phenomenon is shown in the analysis of inquiry process and inquiry activities, as well. Especially, project and field trip introduced in the 7th science curriculum are hardly found in the textbooks. 9th grade is classified as an upper grade in the 7th science curriculum in terms of inquiry level. Integrated inquiry elements and inquiry activity types, however, are not thoroughly reflected in the 9th grade science textbooks. It is desirable that a variety of inquiry learning of 9th grade be implemented by reconstructing inquiry area based on the results of this study. Hence the degree and ratio of utilizing the integrated inquiry elements and inquiry activity types to the inquiry area of science textbook in 9th grade should be studied.

• Journal of the Korean Chemical Society
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• 제29권6호
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• pp.582-591
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• 1985

The thin films of Ti$O_{2-x}$, were prepared by vapor oxidation and Ti$O_2$ single crystal was reduced by heating in argon atmosphere. The photo-electrochemical properties of these samples were studied. When the photocurrent was scanned in 1M NaOH electrolyte solution, several peaks were observed in the vicinity of 320nm in the UV-region and in the vicinity of 520nm, 620nm, and 740nm in the visible-region. Contrary to the previous suppositions, those peaks were produced by the second-order lines from the grating monochromator.

• Applied Chemistry for Engineering
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• 제29권6호
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• pp.789-798
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• 2018

The role of empirical equation to predict the performance of polymer electrolyte membrane fuel cell is important. The activation, ohmic and mass transfer losses were separated in a polarization curve, and the curve fitting according to each region was performed using Kim's model and Hao's model. Changes of each loss were compared according to operation variables of the temperature, pressure, oxygen concentration and membrane thickness. The existing model showed a good fitting convergence, but less fitting accuracy in the separated loss region. A new model using the convergence coefficient was suggested to improve the accuracy of performance prediction of fuel cells of which results were demonstrated.