• Elastomers and Composites
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• 제50권3호
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• pp.159-166
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• 2015

Silica which is used for reinforcing filler in tire industry is widely known as eco-friendly material exerting $CO_2$ reduction effect through decrease of rolling resistance and improvement of wet grip. Generally silica is classified as a highly polar filler because it contains a large number of silanol (Si-OH) group on its surface. And also silica gives a lower reinforcing effect than carbon black due to its poorer rubber-filler interaction. Therefore silica is treated with silane coupling agent or activator, then following the conventional rubber blend method, vulcanized sheets were prepared using a hot press, and cure characteristics, mechanical properties and abrasion resistance of the test specimens were investigated. It was found that with an increase in the silane coupling agent content the tensile strength, 300% modulus and abrasion resistance increased while Mooney viscosity decreased and crosslink density slightly increased with an increase of activator.

• 한국의류학회지
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• 제28권1호
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• pp.112-118
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• 2004

Recently, as the percentage of women employment has been growing, the demand for various facilities and services regarding household duties and infant rearing is increasing and so do the amount of the disposable diaper used. Among the components of disposable diaper, the top sheet contacting with infant skin directly is usually made with nonwoven textiles. Therefore, the mechanical and surface characteristics of the nonwovens used in disposable diaper are important for the skin health of infants. In this study, we have explored the mechanical and surface properties, such as friction coefficient, fluid permeability and strength, of the nonwovens used for disposable diaper top sheet and observed the variation of their properties with abrasion cycles. Nonwoven materials examined in this study are 100% cotton spunlace, 100% tencel spunlace, 100% polypropylene (PP) thermal bonding and 100% PP air through (Thru-air bonded carded web). From the result of KES-F analysis, we've found that 100% PP air through type nonwoven had a low friction coefficient and showed a little change in surface properties as increasing abrasion cycles. Moreover, it revealed superior fluid permeability and quick-drying character. On the other hand, though showing an excellent absorption force, the spun lace type nonwoven made of 100% cotton and 100% tencel displayed relatively low abrasion strength especially in wetting condition.

• 한국철도학회논문집
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• 제2권3호
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• pp.61-69
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• 1999

The durability of ballast plays an important role in track behaviour. To estimate the deterioration characteristics of ballast, several tests have been carried out by several scholars. The deterioration characteristics is very important factor in the behaviour of track and its life. In this paper, abrasion/breakage characteristics of ballast is studied to see the effect of physical ballast characteristics on ballast life. To reveal breakage characteristics of ballast, the ballast box test and the MTT field test were carried out. The breakage characteristics studied in this paper is applied to the ballast life prediction in various conditions, such as LA abrasion, annual tonnage, tamping number per year, etc

• 대한지리학회지
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• 제43권6호
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• pp.808-823
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• 2008

하천 퇴적물질의 마식은 하상과의 충돌과 퇴적물질 입자간의 충돌에 의하여 발생한다. 하천 퇴적물질의 물리적 강도는 마식에 대한 저항의 정도를 나타내는 것으로 정의할 수 있으나, 이에 대한 실증적인 연구는 큰 진전을 보이지 못해왔다. 본 연구에서는 퇴적물질의 마식에 영향을 미치는 요소들(퇴적물질의 물리적강도, 퇴적물질의 크기, 퇴적물질의 양등)의 관계를 파악하기 위해서 마식기를 이용한 물리적 실험을 실시하였으며, 특히 퇴적물질의 물리적 강도가 마식율에 미치는 영향을 분석하는데 강조점을 두고 있다. 이 실험에서는 266개의 퇴적물을 이용했으며, 퇴적물질의 양과 퇴적물질의 평균 무게에 따라 11개의 소집단으로 나눠 실험하였다. 각 실험은 1시간 단위로 이루어 졌으며 퇴적물질은 최장 8시간 동안 마식되었다. 마식율은 각 실험단계마다 퇴적물질 입자 무게의 변동으로 측정하였으며, 총 2,128번의 측정이 이루어졌다. 퇴적물질의 물리적 강도는 시험이 종료한 뒤에 파괴하중을 측정하여 계산한 점 하중강도지수를 통해 측정하였다. 퇴적물질의 점하중강도지수는 마식율과 음의 상관이 있는 것으로 나타났으나, 두 변수들 간의 회귀식의 설명율($R^2$)은 0.22로 나타났다. 퇴적물질의 전반적인 마식은 실험 초기에는 빠르게 진행되지만, 풍화각이 제거된 뒤에는 마식율이 급감하는 경향을 보여주고 있다. 풍화각을 제거하는 초기 단계에는 퇴적물질의 물리적 강도와 마식율의 관계가 미약하지만 이후로 점점 설명율이 상승한다. 이 실험 결과에 의하면 퇴적물질의 물리적 강도는 마식율의 결정적인 설명변수가 아닐 수 있으며, 물리적 속성 이외에도 퇴적물질의 운반조건 등이 마식율에 큰 영향을 주는 것으로 판단된다.

• 한국철도학회논문집
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• 제9권4호
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• pp.401-411
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• 2006

The major objective of this study is to investigate the dynamic behaviors of track due to the deterioration characteristics of ballast for servicing tracks by the field test. The durability of ballast plays an important role in the track behaviour. To estimate the deterioration characteristics of ballast, several tests have been carried out by several scholars. The deterioration characteristics of ballast is one of the most important factor in the dynamic behaviour of track and its life. In this paper abrasion/breakage characteristics of ballast is studied to predict the effect of physical ballast characteristics on ballast track. To reveal deterioration characteristics of ballast, the field test were carried out. The deterioration characteristics, studied in this paper, is applied to the dynamic behaviour of track in various conditions.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.494-507
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• 2006

The major objective of this study is to investigate the dynamic behaviors of track due to the deterioration characteristics of ballast for servicing tracks by the field test. The durability of ballast plays an important role in the track behaviour. To estimate the deterioration characteristics of ballast, several tests have been carried out by several scholars. The deterioration characteristics of ballast is one of the most important factor in the dynamic behaviour of track and its life. In this paper abrasion/breakage characteristics of ballast is studied to predict the effect of physical ballast characteristics on ballast track. To reveal deterioration characteristics of ballast, the field test were carried out. The deterioration characteristics, studied in this paper, is applied to the dynamic behaviour of track in various conditions.

• 구강회복응용과학지
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• 제21권1호
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• pp.69-81
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• 2005

The objective of this study was to evaluate the toothbrush abrasion characteristics of class V restorations. Thirty extracted human premolars, which were collected from oral surgery clinics were used. We mounted five teeth in a metal ring mold of 50 mm in diameter and 15 mm in height using chemically cured acrylic resin. Class V cavities were prepared in lingual cervical root surfaces and restored using one of following restorative materials : Dentin Conditioner/Fuji II LC (Group FL), All Bond II/Z-250 (Group ZT), One-up Bond F/Palfigue Estelite (Group PE), F2000 Primer/Adhesive (Group FT), and Prime & Bond 2.1/Dyract AP (Group DR). They were stored under distilled water at $37^{\circ}C$ for seven days. The toothbrush abrasion test was conducted using a wear testing machine of pin-on disk type under a load of 1.5 N for 100,000 cycles. We have examined the bonded interfaces, the changes of surface roughness and color of abraded surfaces. From this experiment, the following results were obtained. 1. The change of surface roughness showed high degree: RMGIC>compomer>composite resin (p<0.05). 2. Because of the protrusion and missing of filler particles, SEM observation of abraded surfaces of RMGIC and compomers revealed the increase of surface roughness due to the selective removal of matrix resin. 3. The color change by toothbrush abrasion was affected in large part by the change of $L^*$ and $b^*$ of resin composites (p<0.05). 4. The color change by toothbrush abrasion was so small to detect by human eyes. 5. SEM observation of abraded surfaces revealed the interface bonding was the best in the FT group.

• 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.

• 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.

• 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.