• Korean Journal of Organic Agriculture
• /
• v.7 no.2
• /
• pp.163-167
• /
• 1999

To study the effects of chemical and organic fertilizer within the contents of essential elements in the lettuce, in the absence or presence of wood extraction, an experiment was conducted for a period of 10 weeks. The results obtained from the experiment are summarized as follows: 1. The iron contents in the lettuce grown in the chemical fertilized group, were different from those in the organic fertilized group, when the wood extraction was treated. The iron contents in the lettuce increased, due to the wood vinegar treatments, but the modes and degrees were not consistent the various kinds of lettuce. 2. Calcium contents in the lettuce were also increased by wood vinegar treatments, but the modes and degrees were not consistent with the various kinds of lettuce. On the other hand, the Calcium contents in the lettuce grown in the organic fertilized group were reduced by the wood vinegar treatments. 3. The mineral contents within other elements(Manganese, Copper, Zinc) in lettuce, is not variable according to the treatments, or the species of the lettuce.

• Journal of the Korean Chemical Society
• /
• v.66 no.2
• /
• pp.163-170
• /
• 2022

This study investigated and analyzed the social and emotional learning components of middle school science, and high school integrated science and science inquiry experiments, which are common subjects that all students must complete. The subjects of analysis were 139 achievement standards of science and curriculum and 496 activities included in textbooks. The research results are as follows. In the case of curriculum achievement standards, 'cultural understanding' was hardly included among the seven science and social-emotional learning elements, 'numeracy' and 'creative thinking' appeared high in middle school, 'critical thinking', 'social technology' and 'ethical understanding' were included with high frequency in high school. And in the case of textbook activity, the tendency of social-emotional learning elements in middle school and high school was similar. 'critical thinking', 'creative thinking', and 'social skills' were mainly provided, while 'ethical understanding' and 'cultural understanding' were reflected in a limited way. In order to cultivate the elements of overall social-emotional learning, it is necessary to specify the achievement standards of the curriculum or to supplement the textbook activities and teaching-learning process.

• Korean Chemical Engineering Research
• /
• v.50 no.4
• /
• pp.696-701
• /
• 2012

Non-aqueous processes have been developed for stable management and reuse of spent fuels. Nowadays, a plan for the management of spent fuel is being sought focusing on a non-aqueous process in Korea. Named as pyroprocessing, it includes an electrolytic reduction process using molten salt at high temperature for the spent fuels, which provides metallic product for a following electro-refining process. The electrolytic reduction process utilizes electrochemical reaction producing Li to convert oxides into metals in high temperature LiCl medium. Various kinds of elements in the spent fuels would be distributed in the system according to their respective reactivity with the reductant, Li, and the medium, LiCl. This study elucidates the reactions of the elements to understand the behavior of composite elements on the spent fuels by thermodynamic calculations. Uranium and transuranic are reduced into their metallic forms while rare-earth oxides, except for Eu, are stable against the reaction at a process temperature. This study also covers the tendency of reactions with respect to the temperature and, finally, estimates radioactivity and heat load on the distributed phases based on the reference spent fuel characteristics.

• Resources Recycling
• /
• v.29 no.1
• /
• pp.17-24
• /
• 2020

In this study, rare earth elements (REE) leaching from a refractory REE ore containing goethite as a major gangue mineral was conducted, introducing a two-stage method of chemical decomposition-acid leaching. At the chemical decomposition step, using one of alkaline agent, NaOH, the ore was decomposed, changing NaOH concentration from 20 to 50 wt% at 10% (w/w) of pulp density and the maximum temperature achieved without boiling at each NaOH concentration. With increasing NaOH concentration, light REE (Ce, La and Nd) and iron were concentrated in the solid phase which is the decomposed product, while aluminum (Al) and phosphorus (P) were removed to the liquid phase, and their concentrations in the solid phase were down to 0.96 and 0.17%, respectively. In addition, through XRD analysis, it was found that the crystallinity of goethite was considerably decreased. At the acid leaching step, the product decomposed by 50 wt% NaOH was leached at 3.0 M HCl and 80 ℃ for 3 hr, then the REE leaching efficiency was above 94% (Ce 80%), and the leaching efficiencies of Al and P were decreased to 12 and 0%, respectively. Therefore, in terms of both REE leaching efficiency and impurity removal, those decomposition and leaching conditions were chosen as optimum processing methods of the investigated material. In terms of REE leaching mechanism, because REE and iron leaching efficiencies showed the positive correlation each other, so it can be concluded that decreasing crystallinity of goethite affect the improvement of REE leaching.

• Tribology and Lubricants
• /
• v.28 no.1
• /
• pp.7-11
• /
• 2012

In this paper, the results of finite element(FE) analysis of chemical mechanical polishing(CMP) process using 2-dimensional elements were discussed. The objective of this study is to find the generation mechanism of microscratches on a wafer surface during the process. Especially, a FE model with a particle inside pad pore was considered to observe how such a contact situation could contribute to microscratch generation. The results of the finite element simulations revealed that during CMP process the pad-particle mixture could be formed and this would be a major factor leading to microscratch generation.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.1762-1765
• /
• 1997

Some ill-conditioned processes are very sensitive to small element-wise uncertainties arising in classical element-by-element model identifications. For such processes, accurate identification of simgular values and right singular vectors are more important than theose of the elements themselves. Singular values and right singular vectors can be found by iteraive identification methods which implement the input and output transformations iteratively. Methods based on SVD decomposition, QR decomposition and LU decomposition are proposed and compared with the Kuong and Mac Gregor's method. Convergence proofs are given. These SVD and QR mehtods use normal matrices for the transformations which cannot be calculated analytically in general and so they are hoard to apply to dynamic processes, whereas the LU method used simple analyitc transformations and can be directly applied to dynamic processes.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.1826-1829
• /
• 2003

Fine chemical production must assure high-standard product quality as well as characterized as multi-product production in small volumes. Installing high-precision batch distillation is one of the common elements in the successful manufacturing of fine chemicals, and the importance of the process operation strategy with quality assurance cannot be overemphasized. In this study, we investigate the optimal operation strategy and production planning of a sequential multi-purpose plants consisting of batch processes and batch distillation with unlimited intermediate storage. We formulated this problem as an MILP model. A mixed-integer linear programming model is developed based on the time slot, which is used to determine the production sequence and the production path of each batch. Illustrative examples show the effectiveness of the approach.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.4
• /
• pp.447-451
• /
• 2004

Low and high resolution inductively coupled plasma mass spectrometry (ICP-MS) coupled with ion chromatography (IC) has been investigated for speciation of Cr(III) and Cr(VI). In particular, the interference of ArC^+formed by the carbon in a sample on the simultaneous determination of Cr(III) and Cr(VI) has been studied. In chemical speciation, this study shows that quadrupole type ICP-MS with low resolution has a limitation of simultaneous determination fo chromium species if the sample contains the carbon elements. The interference problems can be solved by high resolution ICP-MS.

• 한국생물공학회:학술대회논문집
• /
• 2003.10a
• /
• pp.284-286
• /
• 2003

In order to optimize the culture medium for fumaric acid production using newly isolated fungi, we investigated the effects of various carbon sources and nitrogen sources. When rice bran as nitrogen source was used, the effects of trace elements (phosphate, magnesium, zinc, and iron) on fumaric acid production were also investigated. When initial glucose of 50 g/L and rice bran was employed, maximum fumaric acid was produced without addition of magnesium, zinc, and iron.

• Textile Coloration and Finishing
• /
• v.21 no.3
• /
• pp.19-25
• /
• 2009

Polymerization of tetraethoxysilane on a glass substrate was investigated by remote microwave plasma using argon with portions of nitrous oxide as carrier gas. Transparent layer like a thickness of 0.5 ${\mu}m$ 3 ${\mu}m$ were obtained, differing in chemical composition, depending on plasma power and treatment time as well as on ageing time. In general the milder the treatment and the shorter the ageing was, the higher was the content of organic structural elements in the layer. We have identified that the chemical structure of our samples composed of mainly Si O and Si C groups containing aliphatics, carbonyl groups. These results were obtained by X ray photon spectroscopy, Fourier transformed infrared spectroscopy, and scanning electron microscope combined with Energy dispersive X ray spectroscopy.