• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.925-926
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• 2010

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1990년도 가을 학술발표회 논문집
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• pp.113-116
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• 1990

This study is designed to analyze the variation of grading and shape of aggregate with the number of rotations of Los-Angeles abrasion machine, and is aimed to analyze the effect of slump and compressive strength of strength of concrete with the shape of coarse aggregate by the abrasion act.

• Journal of Periodontal and Implant Science
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• 제31권1호
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• pp.243-258
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• 2001

Gingival recession is exposure of the root surface with apical shift in the position of gingiva. The incidence of gingival recession is 8% in children and 100% after the age of 50. Recession tends to be found in patients with healthy gingiva, but more frequentely found in patients with periodontal disease, and it often causes mucogingival defects. Buccal surface of premolar is the area not only for severe gingival recession and cervical abrasion, but also the area of numbers of buccal frenum and less keratinized gingiva. Threrfore, the goal of this study was to observe the patients with periodontitis and examine whether there are clinical relations between gingival recession and cervical abrasion of premolar and other factors related with the condition of periodontal health. Generally healthy 218 patients who had periodontitis, aged between 18 and 78, were examined for depth of periodontal poket, width of attached gingival, gingival recession, cervical abrasion, and frenum of mid-buccal surface of premolar at the Department of Periodontics in Dankook University Dental Hospital and following is the result. 1. The average gingival recession and cervical abrasion of premolar with periodontal disease was 0.76mm and 0.29mm and each has 43% and 14% of incidence. Also the width of attached gingiva of mid-buccal surface was 1.77mm. the average periodontal pocket depth is 2.0mm and 47% of frequently seen was narrow single shaped frenum, and the interdistance of the frenum was mostly over 4mm. 2. With statistical significance(P<0.05), the incidence of gingival recession increased with age and was related much more with female than male, the first premolar than the second premolar, and with narrow attached gingiva and frenum. 3. With statistical significance(p<0.05), the incidence of cervical abrasion increased with age and was related with the area of the first premolar and narrow attached gingiva, but the sexual and frenum differences were not statistically significant (p>0.05). 4. The severity of gingival recession increased with age and was more related with female than male, the first premolar than the second premolar. And the area of narrow attached gingiva and frenum showed more gingival recession and the distance of frenum was more highly related than shape, and they were statistically significant (p<0.05). 5. With statistical significance(p<0.05), the severity of cervical abrasion increase with age and was observed at the first premolar and narrow attached gingiva. But the sexual and frenum differences were not statistically significant (p>0.05).

• 한국산학기술학회논문지
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• 제10권9호
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• pp.2396-2401
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• 2009

본 연구는 건축자재로 널리 사용되는 PVC 바닥상재의 표면을 스크래치로부터 보호하기 위하여 기존에 사용하는 광경화형 우레탄-아크릴 수지에 내마모성을 향상시킨 광경화형 하드 코팅액 개발에 관한 것이다. PVC 바닥상재용으로 사용되는 내마모성이 없는 우레탄-아크릴 수지에 $Al_2O_3$(Al-160SG-3), $Al(OH)_3$(SH-8W) 및 $SiO_2$(KS-5000) 등 서로 다른 내마모성을 지닌 물질을 분말 형태로 수지의 양 대비 함량(wt%)을 $10{\sim}30%$로 변화하여 첨가한 후 링밀(Ring Mill)을 사용, 배합하여 수지의 내마모성을 향상시킨 하드 코팅액을 제조하였다. 제조한 하드 코팅액은 코팅층의 두께조절이 가능한 코팅(Bar-coating)을 사용하여 PVC 바닥상재에 코팅 한 후 내마모성, 연필경도, 부착력, 코팅두께 등의 코팅층 표면물성을 평가하였다. 연구결과, 수지에 $Al_2O_3$ 분말 30%를 혼합하여 제조한 하드 코팅액이 내마모성 1등급, 연필경도 H, 부착력 100%로 가장 좋은 물성을 보였으며, 전반적으로 입자크기가 작고, 분말 함량이 많을수록 또한 코팅두께가 두꺼워 질수록 경도 및 내마모성이 우수한 것으로 나타났다.

• 한국자동차공학회논문집
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• 제22권5호
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• pp.5-12
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• 2014

Weatherstrip coatings of urethane and silicon type which are fit to EPDM and thermoplastic materials are used in sealing systems for automotive applications for noise reduction and high slip characteristics for external applications, respectively. Polyurethane binder was successfully synthesized from poly(butyladiphate)diol (PBAD), poly(tetramethylene)glycol (PTMG) and isocyanate as starting materials. Then, polyurethane coating agents were prepared by using various additives. To investigate effects of segment types on the abrasion resistance of polyurethane coating agents, thin films based on polyurethane coating materials were fabricated. With increasing the amount of hard segment in the coating agent, abrasion resistance, modulus and tensile strength of the coating films were improved, but the elongation of the coating films was decreased.

• 대한기계학회논문집A
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• 제20권6호
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• pp.1753-1761
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• 1996

The wear behaviors of ${Si_3}{N_4}$ under the different sliding conditions were investigated. The cylinder-on-disc wear tester was used. Using the servo-metor, the sliding speed did ot alternate due to the frictional forces. Threekinds of loads and speeds were selected to watch the variation of the wear rates and the frictional forces. Also three kinds of sliding condition under a constant speed were used to see the effects of the oxidationand the abrasion. The contact pressure was more effective than the repeated cycle on the wear behavior of ${Si_3}{N_4}$. With the low loads, the effect of the asperity-failure was more dominant than that of oxidation and abrasion. As increasing the load, the effects of oxidation and abrasion were increased, but the asperity-failure effects were decreased. The wear particles destroyed the ozide layers formed on sliding surfaces. The wear rate could be decreased due to delaying the oxidation. The frictional power and the wear weight per time were usefuel to see the transition of wear.

• 한국농공학회지
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• 제16권3호
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• pp.3533-3538
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• 1974

This study was attempted in order to search for physical properties of sail cement. In this study, soil samples were specified according to soil particle analysis and used for compaction, strength, abrasion, absorption tests respectively according to different cement contents. Cement content sused in each treatment were 6%, 8%, 10% and 12% of total weight of soil-consent mixture. In the test, compressise strengths of the specimens were measured at the following ages; 3 days, 7-days, 14-days, 21-days and 28-days. Abrasion and absorption tests of the specimens were carried out at the 7-days age only. The results obtained from the tests are summarized as follows; 1. As the cement contents were in creased, the compressive strengths of soil-cement were almost proportionally increased. 2. The Compressive strength of soil-cement was not always proporportional to ages. The gradient of compressive strength of the soil-cement was steeper as the cement content was rucreased. 3. As the cement content was increased, the amount of the weight loss of the samples due to the abrasion was decreased remarkably, giving no abrasion for about 8% of the cement content. 4. As the cement content was increased, the absorption ratio of the specimens was not changed remarkably.

• Elastomers and Composites
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• 제46권4호
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• pp.324-328
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• 2011

신발 밑창용 CIIR에 BR, SBR 및 NBR을 다양한 조성으로 혼합하여 블렌드물의 내마모성과 마찰계수에 미치는 영향을 고찰하였다. CIIR이 BR에 블렌딩됨에 따라 CIIR이 BR의 결정 형성을 방해하며, 이것이 BR/CIIR 블렌드물의 내마모성을 급격히 감소하는 요인 중의 하나로 작용하는 것으로 이해된다. BR/CIIR 블렌드물에서 BR의 함량이 증가함에 따라 $tan{\delta}$ 피크 면적이 저하하였으며, 블렌드물의 마찰계수도 유사하게 저하하는 경향을 나타내었다. CIIR에 BR을 첨가함에 따라 블렌드물의 응력완화율 및 반발탄성이 감소하였으며, 블렌드물의 반발탄성에 영향을 미치는 것으로 추정된다.

• 한국기계가공학회지
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• 제11권1호
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• pp.26-32
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• 2012

Polishing is one of the important methods in manufacturing of Si wafers and in thinning of completed device wafers. This study will report the characteristic of wafer according to processing time, machining speed and pressure which have major influence on the abrasion of Si wafer polishing. It is possible to evaluation of wafer abrasion by load cell and infrared temperature sensor. The characteristic of wafer surface according to processing condition is selected to use a result data that measure a pressure, machining speed, and the processing time. This result is appeared by the characteristic of wafer surface in machining condition. Through that, the study cans evaluation a wafer characteristic in variable machining condition. It is important to obtain optimal condition. Thus the optimum condition selection of ultra precision Si wafer polishing using load cell and infrared temperature sensor. To evaluate each machining factor, use a data through each sensor. That evaluation of abrasion according to variety condition is selected to use a result data that measure a pressure, machining speed, and the processing time. And optimum condition is selected by this result.

• 비파괴검사학회지
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• 제32권1호
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• pp.7-11
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• 2012

기존 진단법과 달리 동적 하중조건하 회전체의 마모 단계에 따른 결함 진단을 위해 비접촉, 비파괴의 적외선 열화상 기법이 제안된다. 본 연구에서는 시험시편인 단열 깊은 홈의 볼 베어링을 설정하여 기존의 스펙트럼 분석과 같은 고장탐지법에 대한 대안으로써 수동형 열화상시험이 수행되었다. 본 연구로부터, 적외선 열화상시험은 신뢰성을 평가하기 위해 기존 진동 스펙트럼 분석시험과 비교, 분석되었다. 연구의 비파괴시험의 결과로써, 마모 단계에 따른 볼 베어링의 온도 특성이 분석되었다.