• The Journal of Engineering Geology
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• v.27 no.4
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• pp.451-462
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• 2017

Physical weathering caused by external forces and chemical weathering caused by the decomposition or alteration of constituent materials are the two factors that dominate the mechanical properties of rocks. In this study, a field investigation was undertaken to identify the physical and chemical weathering characteristics of the biotite granite and granitic weathered soils in Gyeongju, South Korea. Samples were collected according to their grade of weathering and subjected to modal analysis, XRD analysis, XRF analysis, physical property tests, particle size distribution tests, and slake durability tests. Modal and XRD analysis identified these rocks as biotite granite; secondary alteration minerals were not observed. Physical property tests and particle size distribution analyses indicate an average porosity of 41.28% and a sand content of > 90 wt.%. These values are somewhat higher than those of granites in general. The results of the slake durability test and XRF analyses show that the physical and chemical weathering indices of the samples vary with the degree of weathering.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.450-462
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• 2008

The physical chemistry (PC) articles published in the Bulletin of the Korean Chemical Society (BKCS) from 2003 to 2007 are surveyed, and in-depth content analysis was conducted to classify the PC articles into 12 topics used in The Journal of Physical Chemistry (JPC). The PC articles published in the Journal of the American Chemical Society (JACS) in 2007 are also surveyed. The extensive summary of all PC articles in BKCS for the last five years reveals the current trend of physical chemistry research in Korea. The comparison study with the JACS shows that the proportion of PC articles among all articles published in BKCS (16%) is slightly higher than that of JACS (11%), and the non-Korean authorship ratio of BKCS (12%) is very low compared with the non-US authorship of JACS (52%). From the comparison study with articles published in JPC in 2007, it is found that BKCS disseminates various topics of physical chemistry researches adequately. In particular, BKCS most frequently published PC articles in molecular structure and spectroscopy topics, whereas JPC published surface chemistry and nano-chemistry articles most frequently. It is concluded that BKCS should publish more articles to be a leading journal, and it is suggested that the SCI impact factor of BKCS must be increased by improving the electronic version of BKCS.

• Journal of Korean Vacuum Science & Technology
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• v.6 no.3
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• pp.116-119
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• 2002

A performance of a new positron polarimeter is investigated by simulation using a charged-particle trajectory program. The results of the ray tracing are presented along with the details of the design parameters and projected system performance. A ray tracing analysis indicates that this design is capable of effectively transmitting positrons at beam energies varying from 0.1 to 30 keV within the beam diameter of 2-6mm. However, the observed reflection of the positrons(lower than 2 keV) at 12 kGauss indicated that further refinement of beam design is needed to produce a better positron polarimeter.

• Journal of the Korean Society of Tobacco Science
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• v.29 no.1
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• pp.1-7
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• 2007

This study was conducted in order to predict the chemical and physical properties by climatic factors during the growing season of flue-cured tobacco as soon as possible. The data of eight chemical and five physical properties were collected from "Analysis of physical and chemical properties on farm leaf tobacco" conducted at KT&G Central Research Institute from 1987 through 2006. Data of climatic factors from April to July in 10 districts were collected from Korea Meteorological Adminstration. Except for yellowness(b), all probabilities of linear regression equations between the climatic factors(X) and the average contents of twelve grades(whole plant) for chemical and physical properties(Y) were significant($P{\leq}0.05$). The predicable probabilities within ${\pm}20%$ range of difference were 100% in ether extract content, in nicotine content, and in filling value, 90% in total nitrogen content, and 70% in total sugar content. These results suggest that the regression equations may be useful to predict the average content of twelve grades for eight chemical and four physical properties by climatic factors during the growing season of flue-cured tobacco at the beginning of August.

• Journal of the Korean Society of Tobacco Science
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• v.29 no.1
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• pp.8-13
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• 2007

This study was conducted in order to predict the chemical and physical properties by climatic factors during the growing season of burley tobacco as soon as possible. The data of six chemical and five physical properties were collected from "Analysis of chemical and physical properties on farm leaf tobacco" conducted at KT&G Central Research Institute from 1987 to 2006. Data of climatic factors from April to July in 6 districts were collected from Korea Meteorological Adminstration. Except for total nitrogen, total nitrogen/nicotine and yellowness(b), all probabilities of linear regression equations between the climatic factors(X) and the average contents of twelve grades(whole plant) for chemical and physical properties(Y) were significant($P{\leq}0.05$). The predicable probabilities within ${\pm}20%$ range of difference were 100% in ether extract content, 95% in nicotine content, and 90% in filling value. These results suggest that the regression equations may be useful to predict the average content of twelve grades for four chemical and four physical properties by climatic factors during the growing season of burley tobacco at the beginning of August.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.6
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• pp.981-987
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• 2011

Biologically treated water contains a large quantity of organic matters and microorganisms which can cause various problems to membrane. The membrane fouling occurred by these reasons is hard to control by single physical cleaning. This study analyzes the efficiency of aeration with chemical backwashing and foulants removal during chemical backwashing. The cleaning efficiency improves when the chemical concentration is high and the contact time of chemical is long. Chemical backwashing with aeration shows exceptional cleaning efficiency which leads the physical cleaning is required during chemical backwashing since it forms flow inside the membrane submerged tank. From the foulants removal analysis, the particles such as turbidity and TOC removal rate increase when the aeration is applied. Dissolved matter of DOC and UV254 removal is dependent on higher chemical concentration. According to FTIR analysis, one of major foulants, the polysaccharide is controlled by the chemical backwashing with aeration condition.

• Proceedings of the Korean Society of Crop Science Conference
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• 2003.10a
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• pp.162-163
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• 2003

• Journal of the Korean Chemical Society
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• v.47 no.2
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• pp.155-164
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• 2003

This study examined the types of explanations related to physical change and chemical change in the science textbooks of middle and high school based on the prior study of science teachers' understanding. For this research, the researchers analyzed 44 textbooks of middle school science and high school chemistry. As a result, there were no explanation or property type explanation represented in most of the textbooks related to physical and chemical change concepts. Also, there are few relationship represented between physical change and chemical change, and the examples related to physical change and chemical change were confused. These representations of textbooks can give rise to confusion of understanding of teachers and learners. So, it needs to re-design the explanation types correctly and constantly in science textbooks related to physical change and chemical change.

• Near Infrared Analysis
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• v.1 no.2
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• pp.1-8
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• 2000

Using the net analyte signal, hybrid linear analysis was proposed to predict chemical concentration. In this paper, we select a sample from training set and apply orthogonal signal correction to obtain an improved pseudo unit spectrum for hybrid least analysis. using the mean spectrum of a calibration training set, we first show the calibration by hybrid least analysis is effective to the prediction of not only chemical concentrations but also physical property variables. Then, a pseudo unit spectrum from a training set is also tested with and without orthogonal signal correction. We use two data sets, one including five chemical concentrations and the other including ten physical property variables, to compare the performance of partial least squares and modified hybrid least analysis calibration methods. The results show that the hybrid least analysis with a selected training spectrum instead of well-measured pure spectrum still gives good performances, which is a little better than partial least squares.

• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1413-1417
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• 1999

Chemical poisoning of Ni/MgO catalyst was induced by hot alkali carbonate vapor in molten carbonate fuel cell (MCFC), and the poisoned (or contaminated) catalyst was characterized by TPR/TPO, FTIR, and XRD analysis. Carbonate electrolytes such as K and Li were transferred to the catalyst during DIR-MCFC operation at 650 ℃. The deposition of alkali species on the catalyst consequently led to physical blocking on catalytic active sites and structural deformation by chemical poisoning. TPR/TPO analysis indicated that K species enhanced the reducibility of NiO thin film over Ni as co-catalyst, and Li species lessened the reducibility of metallic Ni by chemical reaction with MgO. FTIR analysis of the poisoned catalyst did not exhibit the characteristic ${\vector}_1$$(D_{3h})$ peaks (1055 $cm^{-1},\;1085\;cm{-1})$ for pure crystalline carbonates, instead a new peak (1120 $cm^{-1})$ was observed proportionally with deformed alkali carbonates. From XRD analysis, the oxidation of metallic Ni into $Ni_xMg_{1-x}O$ was confirmed by the peak shift of MgO with shrinking of Ni particles. Conclusively, hot alkali species induced both chemical poisoning and physical deposition on Ni/MgO catalyst in DIR-MCFC at 650 ℃.