• Journal of the Korean Chemical Society
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• v.31 no.6
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• pp.576-581
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• 1987

Synthesis and Biological activity test are described for the (E)-11-tetradecen-1-yl acetate and (Z)-11-tetradecen-1-yl acetate, the sex pheromone of the Asiatic leafroller moth (Archippus breviplicanus Walsingham). 10-Bromodecan-1-ol THP ether was prepared from 10-bromodecan-1-ol. In liquid ammonia with THF and HMPA as cosolvents, sodium acetylide could be alkylated with 10-bromodecan-1-al THP ether to give 11-dodecyn-1-ol THP ether. 11-Dodecyn-1-ol THP ether was then treated with n-Buli in THF to give the lithium acetylide, which was alkylated with bromoethane to afford 11-tetradecyn-1-ol THP ether. 11-Tetradecyn-1-ol THP ether was then reduced over $Pd/BaSO_4$ and with Na in liquid $NH_3$ to give (Z)-11-tetradecen-1-ol THP ether and (E)-11-tetradecen-1-ol THP ether, respectively. (Z)-and (E)-11-Tetradecen-1-ol THP ether thus obtained were deprotected by refluxing in the presence of PPTS and ethanol. (Z)-and (E)-11-tetradecen-1-ol were acetylated with acetic anhydride to afford the final products, (Z)-11-tetradecen-1-yl acetate (1) and (E)-11-tetradecen-1-yl acetate (2), respectively. The synthetic pheromone thus obtained was attractive to the males of the Asiatic leafroller moth in the field.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.2
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• pp.121-126
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• 2015

In general, the pearlescent pigment is a pigment which was used for optical characteristics like pearl, rainbow and metallic luster. Titanium dioxide coated mica plate developed by DuPont in 1965 is currently being used as a main part of pearlescent pigment for cosmetics. Although the smooth and clear surface substrate laminated with 2 ~ 3 ingredients is thicker than a previous monolayer coated substrate, it has been applied for cosmetics as the optical interference powder to realize stronger shine and brighter interference color than monolayer one. In this study, we developed a new optical interference powder with thinner and higher chroma than a current pearlescent pigment for the strong luster and bright interference color. It was prepared from the manufacturing process, in which the coated titanium dioxide precursor was changed and crystallized by coating and heat treatment process with a half of dividing the coated amount of titanium dioxide. We confirmed the dense coating of titanium dioxide grain with Scanning Electron Microscope and measured superior crystallization degree compared with a monolayer coated pearlescent pigment by X-ray Diffraction. It is concluded that our new pearlescent pigment had higher reflectivity of light and stronger interference color than previous products.

• Journal of the Korean Electrochemical Society
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• v.2 no.4
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• pp.232-236
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• 1999

A solar cell based on dye-sensitized photoelectric conversion was studied by electrochemical and spec-trofluorometric methods for the purposes of enhancing its efficiency and stability of $TiO_2$ solar cells. Nanocrystalline $TiO_2$ was used to prepare photoelectrodes, and photosensitizing dyes such as malachite green oxalate, basic blue3, rhodamine B, and bromocresol purple were chosen as sensitizers. Electrochemical oxidation potentials and absorption and emission wavelengths of dyes were used to determine energy levels of the dyes. By comparing excited energy levels of the dyes with the conduction band edge potential $(E_{c,s})\;of\;TiO_2$ calculated by using the flat-band potential $(E_{fb})\;of\;TiO_2$, properties of a dye required to fabricate a high efficient photosensitizing solar cell with high short-circuit current $(J_{sc})$ were suggested. Enhanced stability of photocurrent was obtained by coating a $TiO_2|ITO$ electrode with Polypyrrole that Possibly Prevented the recombination between the conduction band electrons and oxidized dyes and suppressed the direct electrode redox reactions of dyes on ITO.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.1
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• pp.33-38
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• 2009

The use of portable devices has created the need for new reliability criterion of drop impact tests because of the tendency to accidentally drop in the use of these devices. The effects of different PCB surface finishes (organic solderability preservative (OSP) and electroless nickel immersion gold (ENIG)) and high temperature storage (HTS) test on the drop reliability were studied. Various drop test conditions were used to evaluate a drop reliability of assemblies to endure such impact and shock load. In the case of the as-reflowed samples (no HTS test), the SAC/OSP boards exhibited a better drop impact reliability than that of SAC/ENIG. However, the reverse was true if HTS test is performed. In addition, significant decrease of drop reliability was observed for both SAC/ENIG and SAC/OSP assemblies after HTS test. It was also observed that the thickness of intermetallic compound layer do play an important role in the brittle fracture of drop test.

• 대한공업교육학회지
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• v.45 no.1
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• pp.42-62
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• 2020

The Ministry of Education has been quick to apply National Competency Standars (NCS) to industrial sites and educational·training institutions in order to resolve discrepancies between practical affairs in industrial sites and vocational education, training & requirements. Full implementation of NCS-based curriculum in vocational education of vocational high schools has been mandatory since 2018. This research used a region-stratified sample of 350 from teachers in 'machinery' and 'machine·metal' majors in mechanical departments of vocational high schools to investigate the awareness of practical courses for metal machining among the teachers. The research results are as follows. First, a majority of the respondents indicated the availability of turning process, milling process, computer integrated manufacturing and measuring courses in mechanical departments. Second, capabilities required by the industry are considered most in selecting practical courses and competence units. Third, positive changes with the introduction of practical courses in the school education are students' practical skills improvement and satisfaction of industrial requirements. Fourth, negative changes with the introduction of practical courses in the school education are too difficult learning modules used in practical courses for students and students' difficulty in learning because of the difference between equipment in schools and industrial equipment in learning modules. Fifth, teachers' satisfaction with practical courses classes and overall conditions is above the average, and their satisfaction with the level of practical courses and bookbinding or purchase of rearranged textbooks of practical courses is below the average. Therefore, application conditions of above-mentioned representative 4 practical courses should be examined and taken care of for consistent improvement to stabilize NCS-based educational courses in mechanical departments.

• Journal of the Korean Vacuum Society
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• v.22 no.4
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• pp.188-192
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• 2013

Many studies have been conducted for preventing from diffusion between silicon wafer and metallic thin film due to a decrease of line-width and multi-layer thin film for miniaturization and high integration of semiconductor. This paper has focused on the nano-mechanical property of diffusion barrier which sample is prepared for various gas flow rate of nitrogen with tungsten (W) base from 2.5 to 10 sccm. The deposition rate, resistivity and crystallographic properties were measured by a ${\beta}$-ray back-scattering spectroscopy, 4-point probe and x-ray diffraction (XRD), respectively. We also has investigated the nano-mechanical property using the nano-indenter. As a result, the surface hardness of W-N thin film was increased rapidly from 10.07 to 15.55 GPa when the nitrogen gas flow was increased from 2.5 to 5 sccm. And the surface hardness of W-N thin film had 12.65 and 12.77 GPa at the nitrogen gas flow of 7.5 and 10 sccm respectively. These results were decreased by the comparison with the W-N thin film at nitrogen gas flow of 5 sccm. It was inferred that these severe changes were caused by the stoichiometric difference between the crystalline and amorphous state in W-N thin film. In addition, these results were caused by increased compressive stress.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.737-741
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• 2005

In this study, the effect of copper content on the NO removal efficiency by Cu/MCM-41 has been investigated. MCM-41 was prepared by hydrothermal synthesis using a gel mixture of colloidal silica solution and cetyltrimethylammonium. Cu/MCM-41 was manufactured with copper content (5, 10, 20, and 40%) in Cu(II) acetylacetonate. The surface properties of MCM-41 were investigated by using pH, XRD, and FT-IR analyses. $N_2/77K$ adsorption isotherm characteristics, including the specific surface area and micropore volume were studied by BET's equation and Boer's t-plot methods. NO removal efficiency was confirmed by gas chromatography technique. From the experimental results, the MCM-41 was analyzed to have the surface functional groups of Si-OH and Si-O-Si and the characteristic diffraction lines (100), (110), (200), and (210) corresponding to a hexagonal arrangement structure. The copper content supported on MCM-41 appeared to increase the NO removal efficiency in spite of decreasing the specific surface areas or micropore volumes. Consequently, it was found that the copper content in Cu/MCM-41 played an important role in improving the NO removal efficiency, which was mainly attributed to the catalytic reactions.

• Applied Chemistry for Engineering
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• v.19 no.3
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• pp.270-276
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• 2008

$N_2$ doped $TiO_2$ nano-sized powder was prepared using a DC arc plasma jet and investigated with XRD, BET, SEM, TEM, and photo-catalytic decomposition. Recently the research interest about the nano-sized $TiO_2$ powder has been increased to improve its photo-catalytic activity for the removal of environmental pollutants. Nitrogen gas, reacting gas, and titanium tetrachloride ($TiCl_4$) were used as the raw materials and injected into the plasma reactor to synthesize the $N_2$ doped $TiO_2$ power. The particle size and XRD peaks of the synthesized powder were analyzed as a function of the flow rate of the nitrogen gas. Also, the characteristics of the photo-catalytic decomposition using the prepared powder were studied. For comparing the photo-catalytic decomposition performance of $TiO_2$ powder with that of $TiO_2$ coating, $TiO_2$ thin films were prepared by the spin coating and the pulsed laser deposition. For the results of the acetaldehyde decomposition, the photo-catalytic activity of $TiO_{2-x}N_x$ powder was higher than that of the pure $TiO_2$ powder in the visible light region. For the methylene blue decomposition, the decomposition efficiency of $TiO_2$ powder was also higher than that of $TiO_2$ film.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.176-182
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• 2012

The methane dry reforming has received the considerable attention in recent years, mainly as an attractive route to produce synthesis gas (CO, $H_2$) from green-house gases ($CH_4$, $CO_2$) for resources. However, this process has not been commercialized due to the high temperature and catalyst deactivation. In this study, Co-Ru-Zr catalysts supported on $SiO_2$ were studied for the characterization of methane dry reforming reaction and the preliminary data for process development were achieved. The crystal structure of catalysts was measured by XRD, the surface area and pore size were analyzed by BET, and the element composition of catalyst were analyzed by EDS. Conversions of methane and carbon dioxide were analyzed by GC. In addition, reaction rate constants were obtained from the reaction kinetic study and the optimum catalyst size that does not affect mass transfer from reactants was also determined. The selected pellet-type catalyst maintained activation for 720 h at $850^{\circ}C$.

• Korean Journal of Environment and Ecology
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• v.33 no.5
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• pp.596-604
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• 2019

This study conducted a sediment culture experiment to investigate the effects of sediment oxygen demand (SOD) and environmental factors on sediment and water quality. We installed a leaching tank in the laboratory, cultured it for 20 days, and analyzed the relationship between P and Fe in the sediment. As a result, the dissolved oxygen of the water layer decreased with time, while the oxidation-reduction potential of the sediment progressed in the negative direction to form an anaerobic reducing environment. The SOD was measured to be 0.05 mg/g at the initial stage of cultivation and increased to 0.09 mg/g on the 20th day, indicating the tendency of increasing consumption of oxygen by the sediment. The change is likely to have caused by oxygen consumption from biological-SOD, which is the decomposition of organic matter accumulated on the sediment surface due to the increase of chl-a, and chemical-SOD consumed when the metal-reducing product produced by the reduction reaction is reoxidized. The correlation between SOD and causality for sediment-extracted sediments was positive for Ex-P and Org-P and negative for Fe-P. The analysis of the microbial community in the sediment on the 20th day showed that anaerobic iron-reducing bacteria (FeRB) were the dominant species. Therefore, when the phosphate bonded to the iron oxide is separated by the reduction reaction, the phosphate is eluted into the water to increase the primary productivity. The reduced substance is reoxidized and contributes to the oxygen consumption of the sediment. The results of this study would be useful as the reference information to improve oxygen resin.