• 한국산학기술학회논문지
• /
• 제8권3호
• /
• pp.432-436
• /
• 2007

자동차 구조용 재료에 대하여 물리적 증착 코팅방법에 의한 트라이볼로지 특성을 연구 하였다. 코팅 재료는 탄화티탄(TiC)과 질화티탄(TiN)이다. 실험은 펠렉스 마찰 마모시험기를 이용하여 하중과 온도에 다양한 조건을 적용하여 마찰과 마모 거동에 대하여 트라이볼로지 특성을 결정하고 평가하였다. 연구결과 코팅하지 않았을 때보다 코팅하였을 때가 윤활 특성이 향상 되었고, 특히 내마모성 및 극압성 그리고 열 안정성이 훌륭하였다.

• 한국표면공학회지
• /
• 제40권2호
• /
• pp.70-76
• /
• 2007

Ni-P-SiC composite coating layers were prepared by electroless plating method and their deposition rate, codeposition of SiC, morphology, surface roughness, hardness, wear and friction properties were investigated. The deposition rate was kept almost constant independent of the concentration of SiC in the plating solution and the codeposition of SiC in the composite coating layer increased with increased concentration of SiC in the plating solution except the early stage. Vickers microhardness increased with respect to the increased codeposition of SiC and the heat treatment at $300^{\circ}C$ in air for 1 hour. It was found that the wear volume decreased with increased up to 50 wt.% of SiC codeposition, and that friction coefficient increased gradually with increased codeposition of SiC. Considering the wear and the friction behaviors, the composite coating layer obtained by using 50 wt.% of SiC codeposition is desirable for the practical application for anti-wear and anti-friction coatings.

• 대한기계학회논문집
• /
• 제17권12호
• /
• pp.3083-3093
• /
• 1993

Friction and wear at ceramic coated surfaces of aluminum alloy were experimentally studied using a Ring-on-Block wear test machine. Ceramic materials coated on aluminum alloy surfaces were WC, CrC, $Al_{2}O_{3}$ by a plasma spray; and $Al_{2}O_{3}$,$Al_{2}SiO_{5}$, $Na_{2}B_{4}O_{7}$,$Na_{4}P_{2}O_{7}$, and $Al_{2}O_{3}-ZrO_{2}$ composite coating by an Anodic Spark Depositon. They were tested under the sliding wet contact and compared with aluminum alloys and steels. Test results showed that ceramic coated surfaces, in general, have better anti-wear property than those of aluminum alloys due to increase in the surface hardness ; however, they also showed higher coefficients of friction and changes in wear mechanisms, resulting in brittle fractures.

• KSTLE International Journal
• /
• 제10권1_2호
• /
• pp.33-36
• /
• 2009

The nuclear steam generator is composed of a bundle of tubes. The length of these tubes is very long, but their diameter is small. Fluid exists inside of the steam generator and its flow causes vibration, therefore these tubes are supported by anti-vibration bars. The wear damage due to the vibration is known as fretting wear, which should be minimized to ensure the safety of the plants. Research needs to be done about decreasing the amount of fretting wear. Hard coatings have proven to be very effective in reducing the amount of wear. The commercial coatings of TiN and CrN have excellent wear resistance and are used to protect the Inconel tube from fretting wear. The tube-on-flat type tester was used for conducting the fretting wear tests. It was found that the wear amounts of the coated tubes decreased depending on the coating thickness. CrN was found to be very effective in reducing the wear, while the wear amounts were dependent on the coating thickness in the case of TiN and a thick coating of TiN was very effective on wear resistance.

• 한국식품영양과학회지
• /
• 제39권12호
• /
• pp.1739-1744
• /
• 2010

돌단풍 잎의 항산화, 항염, 항당뇨, 항비만 활성을 탐색하고자 강원도 양구에서 자생하고 있는 돌단풍의 잎을 채집하여 에탄올과 증류수로 각각 추출하였다. 항산화 활성은 DPPH 라디칼 소거반응, 총 폴리페놀 함량 및 총 플라보노이드 함량을 측정하여 검정하였다. 돌단풍 잎의 에탄올과 물추출물의 DPPH 라디칼 소거능 $IC_{50}$값은 각각 549.86과 $62.14{\mu}g$/mL이었고, 총 폴리페놀 함량은 에탄올 추출물이 307.63 mg/g으로 물 추출물의 총 폴리페놀 함량인 86.96 mg/g보다 높게 나타났으나 총 플라보노이드 함량은 에탄올과 물 추출물 각각 118.98과 110.16 mg/g으로 비슷한 함량을 나타냈다. 항염 활성은 RAW264.7 세포에 LPS와 돌단풍 잎추출물을 동시에 10 mg/mL 처리하여 NO 생성량을 측정하였으나 효과는 없었다. 항당뇨 활성은 $\alpha$-glucosidase와 $\alpha$-amylase 저해활성을 측정하였으며, 돌단풍 에탄올과 물 추출물의 $\alpha$-glucosidase $IC_{50}$값은 각각 5.62와 $425.63{\mu}g$/mL이었고, $\alpha$-amylase $IC_{50}$값은 각각 4,623.87과 $10,000{\mu}g$/mL 이상으로 돌단풍 에탄올 추출물의 항당뇨 활성은 매우 뛰어났다. 항비만 활성 탐색은 pancreatic lipase의 활성저해를 측정하였으며, 그 결과 돌단풍 잎의 에탄올과 물 추출물의 $IC_{50}$ 값은 모두 $10,000{\mu}g$/mL 이상으로 항비만 활성은 없는 것으로 나타났다. 이러한 결과 돌단풍 잎 추출물의 항산화, 항당뇨의 기능성활용 가공식품 및 건강기능식품으로의 개발이 기대된다.

• 복식
• /
• 제41권
• /
• pp.153-168
• /
• 1998

The purpose of this study is to examine, specifically, the external and internal characteristics of anti-fashion expression in the Korean student movement after the 1945 Liberation. The dress expressed in the student movement represented the purity of student and characterized resistance, and this character expressed strongly in 80s, faded from middle of 90s. Until the 60s, the student movement was not characterized by, so activist students wore dress and suits. It symbolized students as an elite group of society. They added on head-bands to express resistance. In the 70s, activist students wore school uniforms, school military training wear, blue jeans and loose shirts in demonstrations. They tried to express re-bellion against the government and the older gen-eration. In the 80s, the period was remarkably distingusihing by the economic growth at that time. Activist students wore T-shirts with Korean letters and popular paintings specially made, Korean costumes, wrapped in the Taggeuki (Korean national flag), and refused wear on jeans because of anti-Americanism. They also wore masks, muffled their faces, and got their heads shaved. These anti-fashions are very strong expressions for the national independence spirit, national traditional heitage, anti-foreign power and anti-American. In the early 90s, activist students wore reformed Korean costumes specially made group uniforms, after that they wore casual everyday clothes with caps. They tried to express remarkable resistance in the early 90s, but after the mid-90s expression of resistance weakened and faded, so there was no distinction between activist and non-activist. There are the reasons why the student movement changed after the peaceful transfer of political power.

• Tribology and Lubricants
• /
• 제11권1호
• /
• pp.50-57
• /
• 1995

When engine oil is used under severe running condition, the Lubricational characteristics is very important. I have studied the Lubricational characteristics with Compound Additives of engine oil for the Falex wear test machine. Adding detergent (Ca-phenate) to engine oil, the seizure is more improved than in case of non-adding, and adding Zn-DTP (Zinc dialkyl dithio phosphate), the extreme pressure property is excellent at the high load. But when the PTFE (Polytetra Fluoro Ethylene) and MoS$_{2}$ (Molybdenum disulfide) are added, the temperature characteristics and the anti-wear property become excellent because the stability can be maintained in a high temperature. The result are as follows, it can be improved that when the compound of the Ca-phenate and Zn-DTP, MoS$_{2}$, PTFE, etc. was added to engine oil, the lubrication characteristics become better. It is argued that it is improved because of excellence of the anti-wear, the extreame pressure properties and the heat stability.

• 한국공작기계학회논문집
• /
• 제14권2호
• /
• pp.1-7
• /
• 2005

In order to determine the wear Properties of PECVD ceramic coatings, wear process was evaluated using the coated pin of Falex Tribosystem. Coating materials deposited wear the TiC, TiN and Ti(CN). An experimental process was established to determine the tribological characteristics of friction and wear behavior under the variation of applied load, temperature and sliding distance by the Falex test machine. The experimental results indicate that TiN coating compared with TiC coating on e materials have e excellent friction and wear characteristics. However TiC coating compared i친 TiN coatings have a low friction coefficient with steel and good thermal stability, and Ti(CN) has the excellent anti-wear properly as well as the superiority of extreme pressure property. Compound coating compared wi simple coatings show improved tribological characteristics.

• 대한기계학회논문집A
• /
• 제23권7호
• /
• pp.1245-1252
• /
• 1999

The sliding wear behavior of $Al_2O_3/NiCr$ coating deposited on steel(SM45C) was investigated under lubrication. The parameters of sliding wear are normal loads, coating thickness. As a result, the wear resistance of $Al_2O_3/NiCr$ coating was remarkably greater than that of $Al_2O_3$ coating. The optimized coating thickness was found to be $300{\mu}m$ to ensure good anti-wear. The bond coating played important role in decreasing residual stress. The residual stress had much influence on wear mechanism. These results were correlated with the stress state of coating and the microstructure of coating.

• 한국세라믹학회지
• /
• 제31권8호
• /
• pp.874-878
• /
• 1994

To increase the anti-oxidation and anti-wear properties of graphite for the propellant-burning environment, SiC, Pt and Al2O3 multi-layer coatings were conducted succesisvely and the optimum condition was researched. The SiC layer was produced by pack cementation and SiC layer in thickness of 30 ${\mu}{\textrm}{m}$ coating was produced after coating for 6 hours. Pt layer was coated by sputtering, and the Al2O3 layer was coated by reactive sputtering. the thickness of Pt layer and Al2O3 layer was less than one-tenth of that of SiC layer. The pack coated specimens and multi-layer coated specimens were made using above conditions and test-fired. The test result showed that the wear rate of SiC layer is approximately 1/10 compared to that of uncoated graphite.