• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.21-21
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• 2010

현재 시대에는 자원의 부족으로 인하여 원재료의 낮은 등급을 정제하는 것이 중요하다. 자기분리 기술이 산업 계 원재료들의 정제에 적용되는 것이 기대된다. 예를 들면 고순도의 유리나 절연체를 제작하기 위한 원재료에서 철산화물의 제거는 매우 중요하다. 자기를 띠는 입자들과 자기분리 필터 와이어 사이에 발생하는 끌어당기는 힘은 다른 자기분리와 비교 할 때 초전도 자기분리에서 훨씬 강하다. 초전도 마그네트를 이용하여 높은 자기장을 형성하기 때문에 일반 자기분리의 자성 입자 포획력을 능가한다. 본 연구에서는 습식 조건에서 산업계 원재료로부터 철계 산화물을 제거하기 위해서 초전도 자기문리를 사용하여 실험하였다. 실험에 사용된 시료는 유리원료로 사용되는 2종류로 시료A는 0.1 ~ 0.3 mm의 평균입도를 갖는 모래형상이며 시료B는 평균입도 0.03 ~ 0.1 mm의 고운모래 형태이다. 자기분리를 위해 상온에서 100 mm의 직경을 갖는 600 mm의 높이의 전도냉각형 Nb-Ti 초전도 마그네트를 사용하였으며 시료를 위에서 공급하고 아래로 배출되도록 수직형으로 설치하였다. 시료 500 g과 증류수 2 L를 혼합하여 교반시키고 6 T의 자기장 하에서 실험하였다. 자기분리 필터는 초전도 마그네트에서의 자기장의 분포를 해석하여 디자인하였다. 자기분리 필터의 자기적 특성을 알아보기 위해 진동시료형 자력계를 사용하였다. 산업계 원재료는 X선 형광분석기를 사용하여 성분을 분석하였다. 산업계 원재료를 이용하여 초전도 자기분리를 실시한 결과 철계 산화물은 시료A에서 43.5 %제거되었으며 시료B에서는 77.3%제거되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1865-1868
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• 2003

This paper provides a new method for hybrid machining, particularly suited to micro fabrication applications such as micro point, micro line, micro structure, micro partition and so on. Developed micro fabrication process by electrical discharge machining (EDM) and electrical discharge deposition (EDD) with metal powder (Ti, Fe) has been studied to build TiC or FeC structure. Titanium powder or iron powder is supplied from working fluid (kerosene or de-ionized water with powder) and adheres on a workpiece by the heat and electric power caused by the electrical discharge. The use of a tool electrode is expected to keep powder concentration high in the gap between a workpiece and a tool electrode and to accrete powder material on the workpiece. The deposition is tried under various electrical conditions (workpiece. tool electrode, working fluid, discharge current, voltage and powder etc.). On the other hand. using electrical discharge machining (EDM) with the same tool electrode, it can be used as a removal process (cutting) by electro erosion at the same time. Therefore. this new method can do a hybrid machining to build up and down a structure with the workpiece.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 1998년도 가을 학술발표회 프로그램
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• pp.1-1
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• 1998

Advanced (Chemical) oxidation processes (AOP) differ from most conventional ones in that hydroxyl radical(OH.) is considered to be the primary oxidant. Hydroxyl radicalcan react non-selectively with a great number of organic and inorganic chemicals. The typical rate constants of true hydroxyl radical reactions are in the range of between 109 to 1012 sec-1. Many processes are possible to generate hydroxyl radical. These include physical and chemical methods and their combinations. Physical means involves the use of high energy radiation such as gamma ray, electron beam, and acoustic wave. Under an applied high energy radiation, water molecules can be decomposed to yield hydroxyl radicals or aqueous electrons. Chemical means include the use of conventional oxidants such as hydrogen peroxide and ozone, two of the most efficient oxidants in the presence of promoter or catalyst. Hydrogen peroxide in the presence of a catalyst such as divalent iron ions can readily produce hydroxyl radicals. Ozone in the presence of specific chemical species such as OH- or hydrogen peroxide, can also generate hydroxyl radicals. Finally the combination of chemical and physical means can also yield hydroxyl radicals. Hydrogen peroxide in the presence of acoustic wave or ultra violet beam can generate hydroxyl radicals. The principles for hydroxyl radical generation will be discussed. Recent case studied of AOP for water treatment and other environmental of applications will be presented. These include the treatment of contaminated soils using electro-Fenton, lechate treatment with conventional Ponton, treatment of coal for sulfur removal using sonochemical and the treatment of groundwater with enhanced sonochemical processes.

• Corrosion Science and Technology
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• 제15권5호
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• pp.209-216
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• 2016

In the present study, chitosan based self-healing anticorrosion coatings were prepared by layer by layer (lbl) addition of chitosan (Ch) and polyvinyl butyral (PVB) on mild carbon steel substrate. Chitosan coatings exhibited enhanced coating stability and corrosion resistance in aggressive environments by the application of a PVB top layer. Chitosan layer in the lbl coatings have been modified by using glutaraldehyde (Glu) and silica ($SiO_2$). Performance of different coatings was tested using electrochemical impedance spectroscopy and immersion test. The best anticorrosion performance was observed in case of 10 % Ch_$SiO_2$_PVB coatings, which withstand immersion test over 25 days in 0.5 M salt solution without visible corrosion. 10 % Ch_$SiO_2$ coatings without the PVB top layer didn't last more than 3days. Application of PVB top layer sealed the defects in the chitosan pre-layer and improved its hydrophobic nature as well. Raman spectra and SEM of steel surfaces after corrosion study and removal of PVB_Ch/Glu_PVB coatings showed a passive layer of iron oxide, attributing to the self-healing nature of these coatings. Conducting particle like graphene reinforcement of chitosan in the lbl coatings enhanced corrosion resistance of chitosan coatings.

• Archives of Pharmacal Research
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• 제19권2호
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• pp.112-115
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• 1996

Some antioxidant phenolic compounds exhibit prooxidant activity mainly due to their abilities to reduce $Fe^{3+}\; to\; Fe^{2+}.$ Reducing ability and prooxidant activity of maltol, an antioxidant component of Korean red ginseng, were compared with those of pyrogallol. Maltol at 2 mM did not appreciably reduce$ Fe^{3+}\; to\; Fe^{2+}$ and also failed to reduce nitroblue tetrazolium. Stimulation of hydroxyl radical mediated-deoxyribose degradation by pyrogallol was maximal at 60 .mu.M. Maltol stimulated the deoxyribose degradation to a much less extent, and a similar stimulatory effect was observed at a concentration of more than 100-fold higher than that of pyrogallol. The stimulatory effect of maltol reached a plateau over 1 mM, suggesting the removal of hydroxyl radicals by excess maltol. In bleomycin-$Fe^{3+}$-DNA assay, maltol at 2 mM produced a 2.5-fold increase of the iron-bleomycin-dependent DNA degradation over the basal value, whereas pyrogallol at 10 .mu.M accelerated DNA degradation by ca. 10-fold. Furthermore, maltol inhibited $Fe^{2+}$-stimulated DNA degradation by bleomycin. These results strongly suggested that maltol is an antioxidant with little prooxidant activity.

• 한국세라믹학회지
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• 제51권6호
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• pp.570-574
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• 2014

Magnetic-graphene nanosheets have been synthesized via a simple effective chemical precipitation method followed by heat treatment. The composite nanosheets are super paramagnetic at room temperature and can be separated by an external magnetic field. The prepared magnetic-graphene nanosheets were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and BET surface area analysis. The results demonstrated the successful attachment of iron oxide nanoparticles to graphene nanosheets. It was found that the attached nanoparticles were mainly $Fe_3O_4$. The magnetic-graphene nanosheets showed near complete methyl orange removal within 10 mintues and would be practically usable for methyl orange separation from water.

• 한국의류학회지
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• 제6권2호
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• pp.33-40
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• 1982

The removal and redeposition of particulate soil occur simultaneously during the washing process. In order to investigate variables which affect on the redeposition of particulate soil, cotton lawn was soiled in the ion oxide black suspension using Launder-O meter. The amount of deposited soil was estimated by means of the spectrometric analysis of iron on the fabric after soiled. The results are as follows: 1. The presence of surfactants b suspension decreased the deposition of particulate soil and the most effective surfactant was soap and the descending order was NaDBS>CTAB>PONPE. 2. The influnce of temperature on soil deposition was considerable, soil deposition was gradually increased with elevating temperature in ionic surfactants solution such as NaDBS and CTAB but that was decreased above $40^{\circ}C$ in nonionic surfactant solution. 3. The tendency of soil deposition was dwindled by adding electrolytes especially in case of polyvalent anions. 4. From the results of the experiments redeposition of particulate soil was related with suspending power of surfactants and was influenced by factors varing zeta potential.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.37-38
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• 2007

It needs several large reservoirs and long time to remove suspended solid like steel fines and iron oxide in hot rolling coolant. If removing rate of suspended solid in rolling coolant is improved by using high gradient magnetic separation (HGMS) system, the productivity of working process can be increased and the area of reservoir can be reduced. Pre-treatment process that react magnetic floc with inorganic and organic flocculant in coolant was studied. Horizontal type superconducting HGMS system was manufactured successfully, which was constituted with automatic filter transportation apparatus, 6 T He-free superconducting magnet system and water circulation system. The solid suspension removal ratio in hot rolling coolant was increased by flocculation with inorganic and organic flocculant.

• 공업화학
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• 제3권3호
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• pp.451-463
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• 1992

유동층 반응기에서 함티탄자철광의 염소화 반응에 의해 함티탄자철광중의 철분만을 선택적으로 분리할 수 있는 염소화 조건과 아울러 rutile 대용품의 제조 가능성을 조사하였다. 염소화 반응의 적정조건은 반응온도 $950^{\circ}C$, 반응시간 2시간, 함티탄자철광에 대한 환원제 petroleum coke의 무게비 0.12 그리고 염소가스의 유속은 5cm/sec이었다. 이 반응조건하에서 얻어진 반응잔사는 $TiO_2$함량 70%이며 X-선 회전분석 결과 rutile로 확인되는 rutile 대용품이었다.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제26권5호
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• pp.284-289
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• 2023

A 14-year-old girl was admitted to the emergency department for excessive bile-containing vomiting and severe abdominal pain. She had been healthy until she intentionally lost 25 kg over a 6-month period. Thick, bloody bile-mixed food particles were drained from the stomach through a nasogastric tube. Abdominal computed tomography revealed huge stomach dilatation with extensive gastric pneumatosis, possible near rupture, acute pancreatitis, and a very narrow third of the duodenum, indicating superior mesenteric syndrome. Gastrofibroscopy revealed multiple hemorrhagic ulcers and numerous beadlike cystic lesions in the stomach. Laboratory examination results were notable for severe deficiencies in critical nutrients, including iron, zinc, proteins, and prealbumin, as well as undernutrition-associated endocrine complications such as hypothyroidism and hypogonadotropic hypogonadism. Excessive vomiting ceased after the endoscopic removal of stagnant gastric contents. Gastric pneumatosis improved after 3 days of supportive care.