• Asian Journal of Atmospheric Environment
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• 제4권2호
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• pp.80-88
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• 2010

In order to offer a better understanding of air pollution of China as well as East Asia we attempted to characterize the chemical properties of the raw coal materials mined in China and their combusted bottom ashes generated from coal fired power plant. To this end, we measured the chemical characteristics of individual bottom ashes and feed coal fragments collected at a coal fired power generator which was operated with the raw coal dug at a coal mine in China. The chemical properties of these two sample types were determined by a synchrotron radiation X-ray fluorescence (SR-XRF) microprobe method. Through an application of such technique, it was possible to draw the 2D elemental maps in and/or on raw coal fragments and fired bottom ashes. The pulverized fine pieces of feed coal mainly consisted of mineral components such as Fe, Ca, Ti, Ca, and Si, while Fe was detected as overwhelming majority. The elemental mass of combusted bottom ash shows strong enrichment of many elements that exist naturally in coal. There were significant variations in chemical properties of ash-to-ash and fragment-to-fragment. Although we were not able to clearly distinguish As and Pb peaks because of the folding in their X-ray energies, these two elements can be used as tracers of coal fire origin.

• 품질경영학회지
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• 제23권1호
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• pp.106-114
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• 1995

The chemical industry has been a leader in the number of registrations for many decades. The big chemical companies in Korea were clearly committed to ISO 9000 and had strong senior management support. However, not many people in the chemical industry are familiar with ISO 9000 and understand how to develop a ISO 9000 quality manual and how to organize a campaign to get the ISO 9000 registration. The purpose of this paper is to briefly summarize the key concerns of chemical companies and how companies can address those concerns and conform to the various elements of the ISO 9000 standards. The case studies of two domestic and foreign companies in establishing ISO 9000 quality system are also discussed.

• Corrosion Science and Technology
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• 제14권6호
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• pp.273-279
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• 2015

Effects of passive film quality by chemical passivation and solution flow on the corrosion behavior of 304 stainless steel in HCl solution were investigated using a coloration indicator, and by corrosion weight loss, electrochemical polarization and element dissolution measurements. A high redness degree suggests a low passive-film integrity for 304 stainless steel following air exposure, while the minimum redness degree for the samples after chemical passivation suggests a high passive-film integrity. In the static condition, samples subjected to air exposure exhibited a high corrosion rate and preferential dissolution of Fe. Chemical passivation inhibited the corrosion rate due to the intrinsically high structural integrity of the passive film and high concentrations of Cr-rich oxides and hydroxide. Solution flow accelerated corrosion by promoting both the anodic dissolution reaction and the cathodic reaction. Solution flow also altered the preferential dissolution to fast uniform dissolution of metal elements.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.332-335
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• 1995

A simple and effective method for improving Euclidean norm condition number for chemical processing system is presented. The singular value sensitivities of Freudenberg et al. (1982) is used to estimate the behavior of singular values of process transfer function matrix when design parameter is changed, then the condition number can be calculated straightforwardly. The method requires explicit dependencies of each transfer function matrix elements on design parameters. These dependencies can be obtained either by symbolic differentiation in the form of explicit function of design parameters, or by numerical perturbation studies for units with large and complicated models. Gerschgorin-type lower bound for minimum singular value is introduced to detect the large divergencies near singular point due to linearity of sensitivities. The case studies are performed to show the efficiency of the proposed method.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.210-218
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• 2018

Ethylenediaminetetraacetic acid (EDTA)-functionalized KIT-6 and KCC-1 mesoporous silicas were prepared via post-synthesis grafting and examined for their ability to promote the recovery of rare earth metal ions such as $Nd^{3+}$ from an aqueous medium. The obtained adsorption isotherms were fitted to the Langmuir model, which gave a maximum adsorption of $Nd^{3+}$ ions of 109.8 and 96.5 mg/g for KIT-6-EDTA and KCC-1-EDTA, respectively, at $25^{\circ}C$ and pH 6. The adsorption kinetic profile of KIT-6 was faster than KCC-1. KIT-6 was also proved to be more stable against desorption under acidic regeneration conditions.

• 대한화학회지
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• 제48권4호
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• pp.414-426
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• 2004

이 연구는 9학년 과학교과서의 화학분야 탐구영역(탐구과정, 탐구활동)을 제7차 과학교육과정에서 제시한 탐구요소들에 근거하여, 교과서별, 단원별로 분석하였다. 연구의 목적은 제7차 과학교육과정에 제시된 탐구요소들이 중학교 최고학년인 9학년 과학교과서의 탐구영역에 반영된 정도를 알아보고, 다양한 탐구학습을 위한 교육적 시사점을 찾고자 하는데 있다. 9학년 과학교과서의 탐구영역에 대한 전체적인 탐구요소들의 분석에서, 기초탐구요소들은 분류를 제외하고는 제7차 중학교 과학교과서들에 비교적 잘 반영되어 있으나, 통합탐구요소들은 자료해석이 거의 절반을 차지하였다. 이와 같은 현상은 탐구과정과 탐구활동의 분석에서 유사하게 나타났다. 특히, 제7차 과학교육과정의 탐구활동유형으로 신설된 과제연구와 견학은 거의 반영되어 있지 않았다. 제7차 과학교육과정은 과학과의 교수방법 해설에서, 9학년을 탐구의 수준에서 고학년 과정으로 구분하고 있으나, 통합탐구요소들과 탐구활동의 유형들은 다양하게 반영되어 있지 못하다. 그러므로 9학년의 탐구학습은 본 연구의 자료를 바탕으로 탐구영역을 재구성하여 다양하게 운영하는 것이 바람직하다. 앞으로 통합탐구요소들과 탐구활동유형들이 9학년의 탐구영역에 활용되는 정도와 비율에 관한 연구가 계속되어야겠다.

• 대한화학회지
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• 제47권6호
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• pp.633-644
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• 2003

제 7차 교육과정에 의한 화학 I 교과서 탐구영역에서 활용 가능한 탐구 요소들을 조사，분석하여 화학 I 교과서의 제 7차 과학 교육과정 반영 정도와 탐구 학습의 교육적 시사점을 찾고자하였다. 교과서 탐구 영역의 분석은 제 7차 과학 교육과정에서 제시한 탐구 요소들을 기준으로 하였다. 전반적으로 볼 때 제 7차 화학 I 교과서의 탐구 영역 에 기초 탐구 요소는 측정， 분류를 제외하고는 비교적 고르게 반영되어있다. 그러나 통함 탐구 요소는 자료 해석의 비율이 절반을 넘으며， 자료 변환， 결론 도출， 문제 인식은 어느 정도 활용가능하나 그 외의 통함 탐구 요소의 비율은 매우 작다. 탐구활동도 견학과 과제연구 비율은 거의 없거나 이주 작다. 제 7차 과학 교육과정에서는 다양한 탐구 학습 을 강조하고 있음으로， 위와 같은 통합탐구 요소와 탐구 활동의 편중성을 보완할 수 있는 방향으로 탐구 학습을 운영해야 할 것이다.

• Bulletin of the Korean Chemical Society
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• 제32권6호
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• pp.2105-2108
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• 2011

• 대한화학회지
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• 제45권2호
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• pp.183-188
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• 2001

• 대한화학회지
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• 제48권2호
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• pp.203-206
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• 2004