• 해양환경안전학회지
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• 제13권1호
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• pp.39-45
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• 2007

최근 국제 유가의 상승으로 인한 선박 운용비를 절감하기 위하여 중소형 선박에서도 저질연료유의 사용이 검토되고 있는 추세이다. 이 연구에서는 현재 중소형 선박에서 연료유로 사용중인 경유와 중유MF380을 혼합하여 소형선박에 사용이 가능하도록 제조한 혼합연료유인 MF30 연료유에 대하여 그 물리 화학적 특성을 분석하고 정제처리 및 연료유첨가제 효과에 대해 알아보았다. 연구결과 두 가지 전처리 방식인 원심식청정기와 가열 및 균질 방식(M.C.H)의 효과는 다소 미약하였지만, 유동점과 인화점은 다소 낮아졌다. 연료유첨가제로 인한 개질 효과는 뚜렷이 나타나지 않았다.

• 한국해양환경ㆍ에너지학회지
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• 제13권1호
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• pp.43-46
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• 2010

중소형 폐 선박으로부터 배출되는 FRP를 재활용하기 위한 방법으로 층상으로 배열된 로빙층과 매트층을 분리하는 것은 에너지 면에서나 환경적인 면에서 많은 장점을 가지고 있다. 비록 로빙층과 매트층은 모두 유리섬유로 이루어져있으나 수지함유량의 차이와 유리섬유의 조직형태의 차이로 인하여 재활용 용도는 매우 달라지고 있다. 그러나 로빙층은 매트층에 비해 얇은 두께로 존재한다는 이유로 인해 로빙층을 FRP에서 분리할 때 기계가 자동적으로 층간의 차이를 인식하기는 매우 어렵다. 따라서 이 추출과정에서 많은 로빙층의 손실과 공정의 난이도에 의한 처리시간 지연 등의 문제가 발생한다. 본 연구에서는 유리의 구성비가 다른 두 층의 화학적 성질의 차를 이용하여 광학적으로 층간 인식이 가능한 방법을 모색하였다. FRP에 대해 유리의 $SiO_2$와 반응하는 플루오르산(HF) 용액으로 처리한 후 수용성 염료를 도포한 경우 두 층간의 차별화가 확연하게 일어났다. 본 연구는 이 결과를 이용하여 폐 FRP의 면포분리 공정의 효율성을 극대화 할 수 있는 시스템을 개발 하였다.

• Journal of Electrochemical Science and Technology
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• 제14권2호
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• pp.194-204
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• 2023

Models based on diffusion-limited aggregation (DLA) have been extensively used to explore the mechanisms of dendritic particle aggregation phenomena. The physical and chemical properties of systems in which DLA aggregates emerge are given in their fractal. In this paper, we present a comprehensive study of the growth of electrodeposited copper dendrites in flat plate electrochemical cells from a fractal perspective. The effects of growth time, applied voltage, copper ion concentration, and electrolyte acidity on the morphology and fractal dimension of deposited copper were examined. 'Phase diagram' set out the variety of electrodeposited copper fractal morphology analysed by metallographic microscopy. The box counting method confirms that the electrodeposited dendritic structures manifestly exhibit fractal character. It was found that with the increase of the voltage and copper ion concentration. The fractal copper size becomes larger and its morphology shifts towards a dendritic structure, with the fractal dimension fluctuating around 1.60-1.70. In addition, the morphology of the deposited copper is significantly affected by the acidity of the electrolyte. The increase in acidity from 0.01 to 1.00 mol/L intensifies the hydrogen precipitation side reactions and the overflow path of hydrogen bubbles affects the fractal growth of copper dendrites.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제20권3호
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• pp.203-224
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• 2016

The heat and mass transfer characteristics of the unsteady hydromagnetic natural convection flow with Hall current and Soret effect of an incompressible, viscous, electrically conducting, heat absorbing and optically thin radiating fluid flow past a suddenly started vertical infinite plate through fluid saturated porous medium in a rotating environment are taken into account in this paper. Derivations of exact analytical solutions are aimed under different physical properties. The velocity, concentration and temperature profiles, Sherwood number and Nusselt number are easily examined and discussed via the closed forms obtained. Soret effect and permeability parameter tends to accelerate primary and secondary fluid velocities whereas hall current, radiation and heat absorption have reverse effect on it. Radiation and heat absorption have tendency to enhance rate of heat transfer at the plate. The results obtained here may be further used to verify the validity of obtained numerical solutions for more complicated transient free convection fluid flow problems.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
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• pp.42-45
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• 2005

Accurate prediction of the fate and transport of contaminants in soils and sediments is very Important to environmental risk assessment and effective remediation of contaminated soils and sediments. The fate and transport of contaminants in subsurface are affected by geosorbents, especially carbonaceous materials including black carbon. Various physical and chemical treatment methods have been developed to separate different kinds of carbonaceous materials from soils and sediments. However, the effects of these separation methods on the properties of remaining carbonaceous materials including sorption capacity and linearity are unclear. The objective of this study is to determine if the chemical and thermal treatment methods previously used to separate different carbonaceous material fractions affect the properties of carbonaceous materials including longer term sorption capacity of hydrophobic organic contaminants. The results indicate that treatments with hydrochloric acid (HCl)/hydrofluoric acid (HF), trifluoroacetic acid (TFA), sodium hydroxide (NaOH) may not affect the sorption capacity of black carbon reference materials such as char and soot, however, treatments with acid dichromate $(K_2Cr_2O_7/H_2SO_4)$ and heat $(375^{\circ}C)$ for 24 hours in sufficient of oxygen) decrease the sorption capacity of them. The results of longer term sorption isotherm indicate that 2 days might be enough for trichloroethene (TCE) to equilibrate apparently with treated black carbon reference materials. The results suggest that acid dichromate and heat treatments may not appropriate method to investigate sorption properties of black carbon in soils and sediments.

• 대한화학회지
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• 제64권1호
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• pp.7-18
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• 2020

An efficient and facile procedure has been developed for the synthesis of novel bichalcone derivatives (4a, 4b). The key step contains the solvent-free aldol synthesis of bichalcones based on quinones. Bichalcones (4a, 4b) were used as precursors for the synthesis of some interesting heterocyclic compounds like, diazepines (5a, 5b), pyrazolo-pyrimidines (7a, 7b), and pyrazoline derivatives (8a, 8b). Moreover, new thioxopyrimidine derivatives (9a, 9b) were furnished and used as a functionalizing agent to produce the triazole-pyrimidines (11, 12) and the carbonitrile derivative (14). All the synthesized compounds were fully characterized using physical and spectral data like, FT-IR, ¹H NMR, ¹³C NMR, and MS. Bichalcones (4a, 4b) and diazepines (5a, 5b) were screened for their anticonvulsant activity, where compounds (4a, 5a, and 5b) revealed potent anticonvulsant activity compared to diazepam. On the other hand, some of the prepared compounds were screened for their antiproliferative activity and they showed significant cytotoxic effects on most of the cancer cell lines with regard to broad spectrum antitumor activity.

• 한국식품과학회지
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• 제6권2호
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• pp.91-97
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• 1974

This paper was developed for production of the humanized milk, comprising similarly to the composition and characteristic of human milk. Humanized milk of superior quality can be made directly from the fresh raw milk mixed vegetable oil, corn syrup, whey powder, ${\beta}-lactose$, sugar, vitamin, ${\beta}-carotene$ and minerals showing formulation of the humanized milk at table 2. The improving effects of adding vegetable oil and corn syrup are both more reformed the chemical and physical properties of humanized milk. The former enhanced the essential fatty acid and energy source in this product, the latter has the most solving function in water and induced amount of emulsion and stabilizer. The products contain about 13% protein, 23% fat, 58.3% carbohydrate, 2% ash and ensue reasonably balance of essential amino acid, poly-unsaturated fatty acid for the requirement of infants and controlled component of the humanized milk such as human milk.

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.657-662
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• 2012

Mercaptoacetic acid (MAA) and mercaptopropionic acid (MPA) capped ZnS:Mn nanocrystals were synthesized and their physical characteristics were examined by XRD, HR-TEM, EDXS, and FT-IR spectroscopy. The optical properties of the MPA capped ZnS:Mn nanocrystals dispersed in aqueous solution were also measured by UV/Vis and solution photoluminescence (PL) spectra, which showed a broad emission peak around 598 nm (orange light emissions) with calculated relative PL efficiency of 5.2%. Comparative toxicity evaluation of the uncoordinated ligands, MAA and MPA, with the corresponding ZnS:Mn nanocrystals revealed that the original ligands significantly suppressed the growth of wild type E. coli whereas the ligandcapped nanocrystals did not show significant toxic effects. The reduced cytotoxicity of the conjugated ZnS:Mn nanocrystals was also observed in NIH/3T3 mouse embryonic fibroblasts. These results imply that potential toxicities of the capping ligands can be neutralized on ZnS:Mn surface.

• 대한금속재료학회지
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• 제49권10호
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• pp.797-804
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• 2011

In this study, the mechanisms of the three steps (the polymer deposition step, the polymer etching step and the Si etching step) that constitute the Bosch process were investigated. The effects of radicals and ions on each step were quantitatively analyzed by comparing the simulated aspect ratio dependency of the deposition or etch rate with the experimental results. In the polymer deposition step, fluorocarbon polymer is deposited by chemical reactions of $CF_x$ radicals, of which the reaction probability is 0.13. Although the polymer etching step and the Si etching step were conducted under the same conditions, the etching mechanisms of polymer and Si were found to be quite different. In the polymer etching step, both chemical etching and physical sputter-etching contribute to the polymer etching. Whereas, in the Si etching step, Si is chemically etched by F radicals, of which the reactivity is greatly increased by the bombardment of energetic ions.

• 대한방사선기술학회지:방사선기술과학
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• 제44권3호
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• pp.239-245
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• 2021

Since the side effects of contrast agents occur in many ways, hospitals must clearly identify the contrast agents and know how to manage them. Storage of contrast media It is common practice to store contrast media in a warm room to reduce viscosity and improve patient comfort. However, it is important to recognize that long-term storage at high temperatures can shorten the shelf life of a product. Therefore, in this study, the presence or absence of chemical changes according to the storage period after using the contrast medium was analyzed. As the analysis equipment, a 500 MHz Nuclear Magnetic Resonance Spectrometer of Bruker Avance (Germany) possessed by Korea Basic Science Institute (KOREA BASIC SCIENCE INSTITUTE; KBSI) was used. For the X-ray iodide contrast medium, Pamiray contrast medium of Iopamidol and Optiray contrast medium of Ioversol, samples remaining after 7 days, 20 days, 30 days, and 1 year were collected, By acquiring the spectrum from the 1H-NMR spectrometer of the contrast medium stimulated by It was compared and analyzed with the standard sample. In conclusion, depending on the storage period of the contrast medium, no peaks of physical and chemical changes were observed in both the Pamiray contrast medium of Iopamidol and the Optiray contrast medium of Ioversol after 7 days, 20 days, 30 days, and 1 year after use.