• Corrosion Science and Technology
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• 제13권5호
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• pp.163-169
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• 2014

The corrosion resistance of epoxy-coated carbon steel was evaluated. The carbon steel surface was subjected to different treatment methods such as steel grit blasting and power tool treatment as well as contamination of water soluble salt. To study the effect of the surface treatments and contamination, the topology of the treated surface was observed by confocal microscopy and a pull-off adhesion test was conducted. The corrosion resistance of the epoxy-coated carbon steel was further examined by electrochemical impedance spectroscopy (EIS) combined with immersion test of 3.5 wt% of NaCl solution. Consequently, the surface contamination by sodium chloride with $16mg/m^2$, $48mg/m^2$ and $96mg/m^2$ didn't affect the adhesion strength for current epoxy coated carbon steel and blister and rust were not observed on the surface of epoxy coating contaminated by various concentration of sodium chloride after 20 weeks of immersion in 3.5 wt% NaCl aqueous solutions. In addition, the results of EIS test showed that the epoxy-coated carbon steel treated with steel grit blasting and power tool showed similar corrosion protection performance and surface cleanness such as Sa 3 and Sa 2.5 didn't affect the corrosion protectiveness of epoxy coated carbon steel.

• Journal of Nutrition and Health
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• 제30권8호
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• pp.920-929
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• 1997

This study examined the effect of dietary salt levels on the incidence and cure of gastric ulcer in rats. Two sets of experiment were conducted . In the first experiment, the rats were divided into 3 groups. The 3 groups were fed 0%, 4%, and 8% NaCl diets respectively for 20days. The rats were given water -immersion restraint stress at the end of the dietary period , and sacrificed. The ulcer index by histological test was higher in rats fed the 8% NaCl diet than those in the other groups. The hexosamine and glutathione levels were significantly lower in the rats fed the 8% NaCl diet. Hematocrit and total iron binding capacity(TIBC) showed lower values caused by bleeding of gastric mucosa. The second experiment was designed to determine the effect of soldium concentration on the cure of gastric ulcer . As the gastric ulcer was recovered, ulcer length was gradually deceased in the control group but not changed in the 8% NaCl diet group. The gastric hexosamine and hepatic glutathione were increased in the control group but decreased in the 8% NaCl diet group. The hematologic indices of stressed rats showed the same tendency. As a result, dietary salt per se did not cause gastric ulcer . Once an ulcer is formed by stress or any other factor, higher levels of dietary salt may be detrimental to gastric mucosa, thereby delaying the healing of the ulcer. It is recommended that dietary salt intake be reduced in stress-prone people.

• 한국표면공학회지
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• 제49권2호
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• pp.141-146
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• 2016

In this study, electrophoretic paint (E-paint) was deposited on the knife-abraded surface of AZ31 magnesium alloy (AZ31), and its adhesion and corrosion resistance were examined by tape peel-test and salt spray test, respectively. E-paint started to deposit on AZ31 Mg alloy after an inductance time and pores were found in the E-paint layer which is ascribed to hydrogen bubbles generated on the surface during the painting process. The pores disappeared after curing for 15 min at $160^{\circ}C$. The E-paint on AZ31 exhibited good adhesion after immersion in deionized water for 500 h at $40^{\circ}C$. The E-paint sample without scratch showed no corrosion after 1500 h of salt spray test. However, on the scratched sample, blisters were visible adjacent to the scratched sites after 500 h of salt spray test.

• 한국염색가공학회지
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• 제31권3호
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• pp.177-186
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• 2019

In this study, we investigated for synthetic hydrotalcite in chloroprene rubber foam. Experiments were carried out to find the optimum content ratio by controlling the contents of MgO and Hydrotalcite. Swelling test in toluene immersion was made to measure the crosslinking density of CR foams, and the cure properties were investigated with flat die rheometer and Mooney viscosity. The difference of hardness, tensile strength and elongation at break were observed after immersing in 7% NaCl or 21% NaCl solutions for a day and four days. In addition, the volume change and water content remaining in CR foam were measured after immersing NaCl solution. As content of MgO increased, the value of the cure torque tended to increase, but it was almost constant above 2phr of MgO. However, the Mooney viscosity decreased with increasing MgO content. The crosslinking density, determined by the swelling ratio, showed that the CR compound without MgO showed a higher degree of swelling. When the content of hydrotalcite/MgO was 3:2, it was the lowest volume change of CR form. Also, As the content of hydrotalcite decreased, the difference of mechanical properties before and after immersion NaCl solution increased.

• Corrosion Science and Technology
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• 제7권1호
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• pp.13-15
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• 2008

Aiming at the corrosion circumstances and corrosion prevention needs of downhole oil tubes, series protective coatings for downhole oil tubes have been developed in the authors' laboratory, including a baked type coating YG-01 and an air curing type coating YG-03, etc. The performance investigation of the coatings has been done for testing their corrosion resistance, mainly including salt fog test, immersion test in oil-field waste water and various acid solutions, high temperature and high pressure test in alkali solution or $H_2S/CO_2$ environment, as well as some other performances. The investigation results show that oil tube anti-corrosion coatings developed here can endure over 4000 hrs salt fog test, over 1000 hrs immersion in various acid solutions at room temperature and in boiling oil-field waste water. In addition, the coatings can keep intact after experiencing test in alkali solution under 70 MPa pressure at $150^{\circ}C$ for 24 hrs, and in simulative sour gas environment under the total pressure of 32 MPa ($P_{H_{2}S}=3.2MPa$, $P_{CO_{2}}=3.2MPa$) at $90^{\circ}C$ for 168 hrs, which show that the coatings can be used for corrosion prevention in downhole environments with specific high temperature and high pressure, such as sour gas wells. The other testing results show the oil tube protective coatings have excellent comprehensive performance.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.329-331
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• 2013

The salt damage resistance of waterproofing membrane was evaluated on the cracked mortar substrate. The types of specimens are urethane, acrylic waterproofing membrane, and no coating mortar substrate. After these specimens were cured by water curing for 4 weeks, they were cured by atmospheric curing at 20±2Co for 8 weeks. The salt water immersion test was carried out by following KS F 2737, and the penetration depth of chloride ion into substrate was measured in 1, 4, 8, and 13 weeks. As a result, in the case of non coating specimen, the chloride ion penetrated within one week. In the coated specimens, a regardless of the membrane type, the chloride ion did not penetrate during 13 weeks-tests on condition that the cracked width of substrate is less than 0.3mm. Also, the penetration speeds of the coated specimens were lower than that of non coating specimen. Therefore, our results reached a conclusion that waterproofing membrane has high salt damage resistance.

• Composites Research
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• 제24권4호
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• pp.48-54
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• 2011

본 연구에서는 탄소/에폭시 복합재 단일겹침 접착체결부의 염수 수분율이 체결부의 강도 및 파손모드에 미치는 영향을 연구하였다. 시편은 이차접착 방식으로 제작하였고, $71^{\circ}C$, 3.5% 염수환경에서 수분율 0, 0.2, 0.5, 1.0, 2.0%(포화상태)를 갖도록 노출시켰다. 수분율별 시편은 각 8개씩이고, 두 종류의 시험환경을 고려하여 총 80개의 시편에 대한 시험을 수행하였다. 시험결과 복합재 체결부의 강도는 수분율이 2%(포화상태)에 도달하면 감소하지만 그 이전 과도상태(약 1% 근처까지)에서는 오히려 증가하는 것으로 나타났다. 또한 수분율 1%까지는 고온 환경에서의 강도가 상온 강도보다 2~5% 가량 높게 나타났다. 그러나 수분 포화된 고온 환경 체결부의 강도는 상온 강도 대비 약 5% 가량 저하되는 것으로 나타났다.

• 한국터널지하공간학회 논문집
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• 제19권2호
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• pp.283-299
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• 2017

터널의 누수는 콘크리트 라이닝과 같은 구조물의 장기 내구성을 저하시키는 원인이 된다. 내구성 저하 원인은 염화물, 황산염, 물, 가스 등 지하수에 포함되어 있는 여러 가지 물질이 될 수 있다. 본 연구에서는 터널의 지보재로서 또는 방수재로서 사용되는 뿜어붙임멤브레인의 방수성능과 염수에 대한 저항성을 파악하기 위한 기초 시험을 수행하였다. 그 결과, 일부 시험체에서 물의 침투가 발생할 수 있는 것을 파악하였고 그 원인이 액상폴리머와 분말재료의 혼합에 의해 생기는 내부공극과 수압에 의해 내부공극이 연결되어 발생하는 것임을 알 수 있었다. 그리고 증류수와 염수에 침지된 시험체에 대한 인장강도시험을 통해서 인장강도가 기건상태에 비해 절반 이하로 감소될 수 있음을 확인하였다. 또한 신장률은 염수보다 증류수에서 신장률이 더 커지는 결과가 나타났다. 그러나 이 결과는 추가적인 조사가 필요할 것으로 판단된다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2015년도 추계학술대회 논문집
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• pp.189-189
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• 2015

In this study, the corrosion resistance and adhesion of electrophoretic paint (E-paint) were studied on AZ31 magnesium alloy pretreated in cerium chemical conversion coating solutions with the addition of various ethanol concentrations. It was found that with increasing ethanol concentration from 0 to 90 percent can decrease the formation of $Mg(OH)_2/MgO$ and increase the formation of nano-crystalline cerium oxides on the coating. Both corrosion resistance and adhesion of E-painted AZ31 increased with increasing ethanol concentration. The best E-paint sample was observed on the sample pretreatment in cerium chemical conversion coating solution with the addition of 80 percent of ethanol. This sample showed an excellent adhesion without paint detached after water immersion test for 500 h at $40^{\circ}C$, and only a few blisters observed at the near scratched sites after 1000 h salt-spray test.

• 동아시아식생활학회지
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• 제24권1호
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• pp.101-108
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• 2014

본 연구에서는 최근 건강 관리를 위해 다양하게 상용되고 있는 당침액의 오 남용을 막기 위해 과학적으로 물 추출물과 당침액의 특성을 규명하고자 하였다. 그 결과, 일반 물 추출물과 비교하였을 때 당침액의 총 폴리페놀 및 플라보노이드 함량이 크게 감소하는 것을 확인하였으며, 그에 따라 항산화 활성 또한 감소한 것을 확인할 수 있었다. 이는 물 추출물과 비교하여 당침액의 건조 분말에는 설탕 또는 그 분해물들이 많은 부분을 차지하기 때문이라 판단된다. 그러나 혈당강하 효능의 target 효소로 연구되고 있는 ${\alpha}$-amylase 및 ${\alpha}$-glucosidase의 활성을 측정한 결과, 청고추, 쇠비름, 표고버섯의 물 추출물과 당침액은 ${\alpha}$-amylase 억제 활성을 나타내지 않았지만, ${\alpha}$-glucosidase 억제 활성은 의약품인 acarbose에는 미치지 못하였으나, 물 추출물에 비해 당침액이 농도 의존적으로 높은 억제 활성을 나타내었다. 또한 세포 독성을 HepG2 cell에서 확인한 결과, 물 추출물과 비교하여 당침액의 독성이 약 1/10 감소한 것을 확인할 수 있었다. 이와 같은 결과는 민간에서의 믿음처럼 당침액이 물 추출물과 비교하였을 때 모든 부분에서 우수한 기능을 가진다고 할 수 없으며, 활용할 용도에 따라 소재를 물 추출하거나 당침액을 제조하는 등의 가공 과정을 거치는 것이 목표한 기능을 효과적으로 확보하는 방법임을 의미한다. 따라서 민간에서 맹목적으로 믿는 당침액의 효능에 대한 과학적인 연구 접근법은 당침액의 적절한 사용 목적과 방법을 설정하는 기초 자료로 활용이 가능할 것이다.