• Korean Journal of Food Science and Technology
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• v.43 no.3
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• pp.348-360
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• 2011

To verify the volatile compounds contributing to coffee off-flavor, medium roasted Colombian, Sumatra, Ethiopian and light and dark roasted Colombian bean coffees were sequentially and studiously over extracted. Eight espresso samples and eight filter-dripped samples were analyzed by gas chromatography/mass spectrometry with the solidphase microextraction method and evaluated by sensory tests. In total, 67 compounds were detected, and desirable aroma decreased sharply, while off-flavors increased rapidly after 30 mL of espresso and 200 mL of drip coffee. Percent peak area of 4-ethylguaiacol revealed a linear increase during extraction and was highly correlated with increasing off-flavor, suggesting that it could be an indicator of over extraction. Considering the odor activity value, guaiacol and 4- vinylguaiacol were also contributory compounds to off-flavors.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.5
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• pp.423-430
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• 2015

$Cu/ZnO/Al_2O_3$ catalysts for water gas shift (WGS) reaction were synthesized by co-precipitation method with the fixed molar ratio of Cu/Zn/Al precursors as 45/45/10. Copper and zinc precursor were added into sodium carbonate solution for precipitation and aged for 24h. During the aging period, aluminum precursor was added into the aging solution with different time gap from the precipitation starting point: 6h, 12h, and 18h. The resulting catalysts were characterized with SEM, XRD, BET surface measurement, $N_2O$ chemisorption, TPR, and $NH_3$-TPD analysis. The catalytic activity tests were carried out at a GHSV of $27,986h^{-1}$ and a temperature range of 200 to $400^{\circ}C$. The catalyst morphology and crystalline structures were not affected by aluminum precursor addition time. The Cu dispersion degree, surface area, and pore diameter depended on the aging time of Cu-Zn precipitate without the presence of $Al_2O_3$ precursor. Also, the interaction between the active substance and $Al_2O_3$ became more stronger as aging duration, with Al precursor presented in the solution, increased. Therefore, it was confirmed that aluminum precursor addition time affected the catalytic characteristics and their catalytic activities.

• Resources Recycling
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• v.19 no.6
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• pp.61-69
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• 2010

S.M.C (DSME), only operating gold mine in Korea, is processing about 160 ton/day to recover gold and more than 150 ton/day of tailing is produced. Some portion of the tailings are used as a filler material after drying, but most of them are stored on the tailing dam. As a result of chemical analysis by a fire assay method, it contained Au 1.5~2.0 g/ton and 225~300 g per day of gold is getting discarded. It is urgent to develop a technology to recover and reutilize Au. In the present study, flotation tests were carried out to recovery gold for the tailings. Test results show that products with gold grade 21.31 g/ton(Au grade) and 62.73% (Au recovery) were obtained under the optimal conditions including KAX addition rate 97.2 g/ton, frother AF 65 (0.248 l/ton) and depressant sodium silicate (4 kg/ton), it's possible to recover one of the most valuable metal Au, by re-feeding to rougher flotation.

• Economic and Environmental Geology
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• v.38 no.1
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• pp.91-99
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• 2005

Acid Rock Drainage(ARD) is the product formed by the atmospheric(i.e. by water, oxygen and carbon dioxide) oxidation of the relatively common iron-sulphur mineral pyrite($FeS_2$). ARD causes the acidification and heavy metal contamination of water and soil and the reduction of slope stability. In this paper the generation characteristics and the prediction of ARD of various cut slopes were studied. An attempt to classify the rocks into several groups according to their acid generation potentials was made. Acid Base Accounting(ABA) tests, commonly used as a screening tool in ARD predictions, were performed. Fourteen rock samples were classified into PAF(potentially acid forming) group and four rock samples into NAF(non-acid forming) group. The chemical analysis of water samples strongly suggested that ARD with high content of heavy metals and low pH could pollute the ground water and/or stream water.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.48 no.2
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• pp.123-134
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• 2022

In this study, the whitening and antioxidant effects of the extracts from Hydrangea petiolaris (H. petiolaris) leaves was confirmed, and the chemical structure was identified by separating the active ingredients. In the whitening tests using α-MSH stimulated B16F10 melanoma cells, the n-hexane (Hex) fraction inhibited the cellular melanogenesis and intracellular tyrosinase activities without causing cell toxicity. In addition, the Hex fraction reduced expression of tyrosinase and TRP-2 protein. Upon the anti-oxidative studies by DPPH and ABTS⁺ radicals, potent radical scavenging activities were observed in the ethyl acetate (EtOAc) fraction. Also, for the cellular protective effects on HaCat keratinocytes damaged by H₂O₂, the EtOAc fraction indicated protective effects against oxidative stress. Eight phytochemicals were isolated from the extract of H. petiolaris leaves; ethyl linoleate (1), ethyl linolenate (2), 1-linoleoyl glycerol (3), 1-linolenoyl glycerol (4), epi-catechin (5), afzelin (6), quercitrin (7), hyperin (8). Among the isolates, the compounds 5 - 8 showed DPPH and ABTS⁺ radical scavenging activities. The contents of quercitirin, a major isolated in this extract, determined by HPLC analysis were confirmed to be about 31.3 mg/g for the 70% ethanol extract and 169.8 mg/g for the EtOAc fraction. Based on these results, it was suggested that the extract from H. petiolaris leaves could be potentially applicable as whitening and anti-oxidative ingredients in cosmetic formulations.

• Journal of the Korea Institute of Building Construction
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• v.23 no.3
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• pp.231-240
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• 2023

In this research, our goal was to explore the potential use of cement mortar augmented with liquid red mud. To facilitate this, we neutralized liquid red mud(LR) - exhibiting a pH of 10-12 - using sulfuric acid to yield sulfuric acid neutralized red mud(SR). We then evaluated the flow, setting time, and compressive strength of the cement mortar combined with liquid red mud, while also performing a thorough examination of its chemical properties through X-ray diffraction(XRD) and scanning electron microscopy(SEM). The flow tests indicated a decrease in flow values for both MS-LR and MS-SR in comparison to the Plain. Analogously, the setting time for MS-LR and MS-SR was found to be abbreviated when juxtaposed with the Plain. With regards to compressive strength, MS-LR demonstrated a surge in strength at the 1-day mark, while MS-SR displayed a diminution at the 1-day and 3-day timepoints compared to the Plain. XRD analysis illustrated that after 28 days, the XRD patterns of Plain and MS-SR bore significant resemblance, though a new peak was detected in MS-LR. SEM imagery highlighted that the microstructures of Plain and MS-SR were alike, but MS-LR manifested a distinct microstructure, characterized by a finely fibrous formation. Based on these observations, we infer that the replacement of cement mortar with liquid red mud neutralized with sulfuric acid contributes to a noticeable enhancement in strength, thereby verifying its suitability for this application.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3C
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• pp.159-165
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• 2010

The problems such as natural resource exhaustion, pollutant emission and waste generation are increasing worldwide with the industrial development. The quantity of the industrial by-product in Korea is 6 million tons a year, and even its basic treatment processes including landfill, incineration and storage have reached their limits. In this study, fly ash and silica fume were applied to shotcrete to develop a method for the reuse of resources and to increase the use of fly ash, which is an industrial waste. An environmental hazard evaluation is a must to actively address the worldwide environmental problems, though. Therefore, an environmental impact assessment was conducted using the chemical content analysis test and heavy metal exudation test, for ten mixtures that were obtained through the pre-mixing and compressive strength tests. The results of the compressive strength test showed that all mixtures satisfied national and international standards. Cr, Cd and Hg were not detected, and Pb was detected only in some cases with fly ash. Cu and As were detected in all mixtures, but all of them satisfied national and international standards.

• Korean journal of applied entomology
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• v.62 no.4
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• pp.355-363
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• 2023

In addition to causing direct feeding damage to a variety of greenhouse crops, Frankliniella occidentalis also inflicts indirect harm by facilitating the transmission of the tomato spotted wilt virus. Historically, the prevention of F. occidentalis infestations has relied heavily on pesticide use. However, this approach has led to significant side effects in agricultural ecosystems, including the development of pest resistance and challenges in effective prevention. In response to these issues, research has been directed towards identifying alternative substances that circumvent the tolerance developed against chemical pesticides. Extracts from sixty-seven medicinal plants were prepared by soaking them in water for 24 hours at room temperature. These extracts were then applied to adult F. occidentalis, with particular attention to moutan extract treatment. This treatment demonstrated a 100% insecticidal effect on the first day. The moutan extract, specifically, was prepared using 50% ethanol, after which the ethanol and water were removed via a rotary evaporator. The resultant product was then lyophilized into a powder and used after being diluted with water. In indoor experiments, a 40% diluted solution was sprayed onto F. occidentalis, exhibiting a 100% insecticidal effect 24 hours post-treatment. Furthermore, a pot test indicated a 78% insecticidal effect on the first day of application. Ongoing research includes the analysis of active substances that demonstrate exceptional insecticidal properties and the conduct of on-site validation tests. The application of the aforementioned extract is anticipated to be effective in the prevention of F. occidentalis infestations.

• Journal of the Korea Institute of Building Construction
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• v.23 no.6
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• pp.693-702
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• 2023

This research explores the potential application of Liquid Red Mud(LRM), a byproduct of industrial processes, in the construction sector. We neutralized LRM(pH 10-12) using nitric acid, aiming to understand its viability in construction applications. The study involved substituting LRM(pH 7-8) in mortar formulations, varying by cement type. We assessed the properties of these mixtures by measuring flow, setting time, and compressive strength. Additionally, X-ray Diffraction(XRD) and Scanning Electron Microscopy(SEM) analyses were conducted to examine the chemical properties. Results indicated a reduction in flow value for LRM and LN(neutralized LRM) compared to the control (Plain ) across different cement types. The setting times(initial and final) for LRM and LN were notably shorter than Plain. In compressive strength tests, LRM replaced with slag cement showed enhanced initial strength, though long-term strength gains were marginal across different cement types. SEM analysis revealed distinct voids in Plain and LN, with LRM exhibiting a fibrous microstructure. XRD patterns in SN(slag neutralized) resembled those in OR(original red mud) and ON(original neutralized), with a notable peak at a 2θ value of 22°. The study concludes that unneutralized LRM, when substituted for slag cement in mortar, yields superior initial strength compared to its neutralized counterpart.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.2
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• pp.194-199
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• 2024

Accidents due to aircraft fuel defects rank in the top 13 of the 34 accident types described by CAST-ICAO Common Taxonomy Team(CICTT). Aircraft accidents occur because of the inflow of moisture or pollutants depending on the distribution process and storage environment. To confirm the change in physical properties of the aircraft oil stored for a long time, we stored JET A-1 aircraft oil in a metal can to observe the change after six months. We confirmed that the aircraft oil stored for a long time satisfied the quality standards, and the stability of the fuel oil was high. However, in scenarios in which aircraft oil is stored separately on ships, onshore storage facilities, oil fields, etc., owing to the nature of missions, such as in marine police aircraft, the inflow of moisture or pollutants may likely occur due to changes in the internal and external environment. In addition, pollutants can be analyzed using existing tests and distillation properties, but for moisture, domestic and international standards and domestic laws determine the moisture separation ability of aircraft oil through the water separation index, but the moisture content is not analyzed. Therefore, aviation safety must be secured by adding quality control standards for moisture content and performing revisions to uniformize domestic and international standards and laws.