• Proceedings of the KWS Conference
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• 2005.11a
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• pp.225-227
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• 2005

Sn-8wt%Zn-3wt%Bi (이하, Sn-8Zn-3Bi) 솔더의 장기 신뢰성을 평가하기 위하여 열 충격 시험을 행하였다. 열 충격 시험은 $-40^{\circ}C$에서 $80^{\circ}C$범위에서 1000 사이클 동안 하였다. 접합 기판으로는 각각 OSP(Organic Solderability Preservative), Sn 그리고 Ni/Au 처리를 한 PCB(Printed Circuit Board) 패드를 사용하였다. 접합에 사용한 부품은 1608 Chip(Multi Layer Chip Capacitor, Chip Resistor) 으로 전극 부위에 Sn-37wt%Pb, Sn 도금하여 사용하였다. 솔더링 후 1608 Chip의 전단 강도와 솔더링부에서 미세조직 및 IMC(Inter Metallic Compound) 변화를 관찰하였다. 측정결과, Sn-8Zn-3Bi 솔더의 초기 전단 강도는 기판의 표면처리에 상관없이 약 40N 이상이었다. 그리고 열충격 시험 1000 사이클 후에는 모든 기판에서 2N 정도 약간의 강도 저하를 보였다.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.2
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• pp.174-184
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• 2020

Objectives: The purpose of this study was to improve the working environment by identifying the work satisfaction of the cleaning workers of the aircraft and measuring and assessing the harmful factors of the cleaning process. Methods: We asked 23 cleaning companies for questionnaires and got 100 answers from 5 companies. The A-E Airline health manager has been contacted to establish a site survey schedule. The in-flight and lounge were measured using direct reading equipment. The harmful factor to be measured are noise, dust, temperature, volatile organic compound, total airborne bacteria, and total airborne bacteria. Results: Uncomfortable positions when replacing blanket, cleaning the table, and cleaning the floor have been identified as factor that reduce work satisfaction. Noise when replacing newspapers and cleaning toilets has been identified as a factor that lowers work satisfaction. Temperature and humidity were found to reduce work satisfaction during in-flight disinfection. Measurements of aircraft cabin and lounge with direct read equipment have shown that none of the items exceed the exposure criteria. Conclusions: As a result of measuring direct-reading equipment, no items exceeded the exposure criteria for each harmful factor. A clear survey of the working environment is required based on the results, and additional research is needed using personal sample measurement.

• International Journal of Automotive Technology
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• v.4 no.2
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• pp.95-100
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• 2003

Automobile industry has been developed rapidly as a key manufacturing industry in Korea. Meanwhile, air pollution is getting worse noticeably than ever. In the diesel emission, PM (Particulate Matter) and NOx (Nitrogen Oxides) have been exhausted with a great amount and the corresponding emission regulations are getting stringent. In order to develop low emission engines, it is necessary to research on better qualified fuels. Sulfur contained in fuel is transformed to sulfur compound by DOC (Diesel Oxidation Catalyst) and then it causes to the increase of sulfate-laden PM on the surface of catalyst. In this research, ULSD (Ultra Low Sulfur Diesel) is used as a fuel and some experimental results are investigated. ULSD can reduce not only PM but also gas materials because cetane value, flash point, distillation 90%, pour point and viscosity are improved in the process of desulfurization. However, excessively reduced sulfur may cause to decease lubricity of fuel and engine performance in fuel injection system. Therefore, it requires only modest adjusted amount of sulfur can improve engine performance and DOC, as well as decrease of emission.

• Textile Coloration and Finishing
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• v.27 no.4
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• pp.275-280
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• 2015

New series of phthaloperinone dyes were synthesized by the condensation reaction between tetrachloro-phthalic anhydride, 2,3-naphthalene dicarboxylic anhydride and o-phenylenediamine, 1,8-diaminonaphthalene, 1,2-diaminoanthraquinone. These dyes absorb at around 370-490nm. It was found that introduction of naphthalene and anthraquinone moiety on the perinone system produces a large bathochromic shift of 100nm. The synthesized dye 7 containing anthraquinone moiety in perinone chromophoric system exhibited superior heat stability and bright color as yellow chromophore. New dye 7 have been investigated in terms of interacting with volatile organic compound(VOC) $EtNH_2$. The sensing behaviour of the dye 7 toward $EtNH_2$ was studied by UV-vis absorption spectroscopy. Sensing mechanism of dye 7 to $EtNH_2$ was supported by theoretical calculations based on DFT method.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.459-466
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• 2007

In this study, H-type beta zeolites (BEA) having various metals were used as the adsorbent for the removal of sulfur containing odorants. The different adsorbents containing single or bimetals were utilized to investigate the performance in the individual adsorption of TBM and THT odorants or in the competitive adsorption between them by using a continuous adsorptive bed system. The result shows that the pure H-type BEA zeolite exhibited the highest adsorption capacity for TBM compound, but the higher amount of THT was removed and adsorbed on a HBEA adsorbent having Fe, Pd metal and ZnO oxide. In the case of bimetal containing adsorbents, Cu-Zn/HBEA and Fe-Mo/HBEA showed a higher adsorption capacity for TBM.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.6
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• pp.791-798
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• 2006

In order to investigate the NVOC (Natural Volatile Organic Compound) emissions from White Oak, the emission rates of isoprene were measured according to season, weather conditions, and the age of the tree. The analysis of seasonal emission rates showed that the emission rates were the highest during summer followed by spring and fall. The emission rates during summer were found to be nearly 8 times greater than those during fall. In addition, it was observed that the emission rates of isoprene depends on PAR and temperature. Moreover, the effect of age on the emission rates was studied, and the White Oak in the age range of $21{\sim}30$ had higher emission rates than that in the range of $41{\sim}50$. Accordingly, the current result indicates that the isoprene emissions are affected by both meteorological parameter and the age of a tree.

• Economic and Environmental Geology
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• v.26 no.2
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• pp.217-226
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• 1993

Stream sediment samples were collected in the vicinity of the Sambo Pb-Zn-barite mine in order to investigate dispersion patterns and pollution levels of heavy metals, and to find out their mode of occurrences. Those samples were analyzed for Cd, Cu, Pb, Zn, Fe, and Mn by using partial extraction and sequential extraction methods. Stream sediments of this studied area has been contaminated severely by Pb, Zn, and Cd. Dispersion patterns of heavy metals in those sediments are different according to their pollution source and sampling distance from the mine. The stream sediment pH is generally neutral in control area, and is slightly acidic in the lower part of tailing dam. The main pollution source of stream sediments was confirmed as tailing and mine drainage. Their pollution level depends mainly on inflowed water and distance from the mine. The tolerance index ranges from -0.9 to 0.7. The mode of occurrances of heavy metals in polluted stream sediment are identified as Fe-Mn oxides, organic bounded and carbonate-bounded compound which show high potential of bioavailablity.

• KSBB Journal
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• v.20 no.5 s.94
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• pp.383-386
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• 2005

Grape seed oil made by press or organic solvent extraction does not contain resveratrol, a bioactive compound. Supercritical carbon dioxide could extract oil containing resveratrol from grape seed. The extraction efficiency was mainly dependent on the water content in grape seed. More resveratrol was contained in the oil extracted with un-dried grape seed. No resveratrol was extracted with dried grape seed. Time course changes of grape seed oil extraction also resulted that resveratrol could be extracted by supercritical carbon dioxide with the positive influence of water.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11b
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• pp.23-26
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• 2004

Monolayers of lipids on a water surface have attracted much interest as models of biological membranes, but also as precursors of multilayer systems promising many technical applications. Until now, many methodologies have been developed in order to gain a better understand. Photoisomerization in monolayers of a novel azobenzene compound, azobenzene dendrimer, was investigated for the first time by means of the absorption spectrum and Maxwell displacement current(MDC) technique. Dendrimers are well-defined macromolecules exhibiting a tree-like structure, first derived by the cascade molecule approach According to the absorption spectrum, trans-to-cis conversion ratio was estimated to the third generation of azobenzene dendrimer deposited onto a glass substrate. Temperature-dependent induced charge with trans-cis isomerization was also measured by means of MDC technique.

• Journal of the Korean Chemical Society
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• v.8 no.4
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• pp.135-141
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• 1964

The reaction of potassium fluoride with amyl iodide in presence of dimethylformamide at low temperature gave a fluorination product together with decane. Polyhalogenated acid such as ${\alpha}$, ${\beta}$,-dichloro-${\beta}$-phenyl-propionic acid gave ${\alpha}$-chlorostyrene, fluorinated styrene, and fluorinated acid. The same reaction with the ethyl ester did not give the fluorination product and gave a mixture of various dimerized product. Dibromostyrene gave bromostyrene together with fluorination product. Iodo acid such as m-iodo acid gave the salt and a trace quantity of dimerized product. Iodides such as m-iodotoluene and 1-amino-4-iodo-2-methyl benzene did not show any appreciable reactivity towards potassim fluoride. The reaction condition was described, and fluorination, ${\alpa}$-dehydrofluorination, decarboxylation, and dimerization were discussed.