• International Journal of Highway Engineering
• /
• v.11 no.2
• /
• pp.111-120
• /
• 2009

This paper presents a fundamental findings of the functional and structural performance of the porous asphalt concrete coated with MMA resin. To evaluate the structural performance, cantabro, wheel tracking, moisture sensitivity and indirect tensile fatigue tests are performed. The tests results show that the cantabro loss is reduced three times and fatigue resistance is significantly increased after the specimens are coated with MMA resin. However there are little changes in the rutting and moisture damage resistances before and after the coating. Air voids, permeability and BPT(British Pendulum Test) tests are conducted to study the functional performance. It is observed form the tests that the air voids and permeability are slightly decreased after the coating. However, the changes in the air voids and permeability are negligible. The skid resistance of the coated specimens is lower than reference specimens. However, the skid resistance is maintained beyond the level of the reference specimens when silica sands are chipped on top of the coated surface.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.2
• /
• pp.58-65
• /
• 2021

As increasing social needs of pavement maintenance, pattern frame method has been constructed in Korea. The pattern frame not only increases the skid resistance of pavements but also improve the scenery. However, construction of the pattern frame currently relies on imported materials. In this paper, we localize the materials used in pattern frame and conduct performance verification on them. The important performance indicators are the adhesion strength of undercoating materials and the skid resistance of finished pattern frames. The adhesion strength was targeted at 1.4MPa, and the localization alternative material met the target performance with 2.35MPa, the skid resistance performance was targeted at 40BPN, and the localization alternative material met the target performance with 75BPN. In the case of localized materials, approximately 40% cost reduction (per 1m²)compared to imported materials was confirmed.

• International Journal of Highway Engineering
• /
• v.8 no.3 s.29
• /
• pp.77-88
• /
• 2006

The maintenance / repair of concrete pavements has become an issue as a result of increasing of concrete pavements' service year. Asphalt overlay is applied to the concrete pavements after partial repairs on all occasions. This thesis discusses the application standard, evenness, skid resistance, noise, economical efficiency, extension of life span, etc. of diamond grinding, a method of maintenance about concrete pavements. Based on this, it was applied to the field and measured the performance. It was measured the longitudinal evenness of before and after the construction through measurement equipment. and surveyed the skid resistance the each lane classified using the SN standard value. In case of noise, it is selected the kind of vehicle, velocity, then measured the noise between control and constructed site. In addition, it is evaluated the average texture depth. As a result of the analysis, longitudinal evenness is improved about $6{\sim}40%$, skid resistance is improved 66% at first section,37% at second section. Noise is reduced 3.4dB average, and average texture depth is 79% deeper than control section. Therefore, it can be concluded that diamond grinding is suitable as maintenance / repair method of concrete pavements.

• 한국도로학회:학술대회논문집
• /
• 2004.02a
• /
• pp.101-106
• /
• 2004

• 한국도로학회:학술대회논문집
• /
• 2003.10a
• /
• pp.183-188
• /
• 2003

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.03a
• /
• pp.26-26
• /
• 2003

본 연구에서는 누적압연접합공정(ARB)을 통하여 5052 알루미늄 합금의 결정립을 약 0.2$\mu\textrm{m}$ 크기로 미세화 하였다. 누적압연에 의한 변형량 증가에 따른 미세 조직 변화와 결정립 간의 상대적인 방위각 차이를 TEM을 이용하여 관찰하였다. 누적 변형량을 함수로 상온 인장특성을 분석하였고, 초미세립 소재를 후속 열처리한 후 미세 조직 변화를 관찰하여 제조된 초미세립 소재의 열적 안정성을 평가하였다. 상온 대기 중에서 pin-on-disk 형태의 마멸시험기를 사용하여 초미세립 소재의 미끄럼 마멸시험을 변형량과 하중을 변수로 행하였다. 강소성 변형에 의해 제조된 5052 알루미늄 합금 소재의 마멸저항성은 강소성 변형 전과 비교하여 소재의 경도가 크게 증가하였음에도 불구하고 오히려 감소하였다. 마멸시험 후 마멸면의 SEM, 마멸단면의 OM 관찰과 마멸면 직하의 깊이에 따른 경도측정을 통하여 초미세립 소재의 마멸기구를 분석하였고 마멸표면의 변형 층을 관찰하였다. 또한 마멸면 직하 조직의 TEM 관찰을 통해서 마멸시험 중의 미세 조직 변화를 연구하였다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.9
• /
• pp.1073-1080
• /
• 2012

Incremental forming is a cold working process in which a small part of the material is being deformed and the area of local deformation is moving over the entire material. In this paper, we study description schemes to perform finite element analysis for the incremental forming. The selected description schemes to examine are the Lagrangian description and the arbitrary Lagrangian-Eulerian (ALE) description. The sliding boundary scheme coupled with ALE is also examined to overcome the distortion problems of elements on the contact surface. Results show that the ALE description with the sliding boundary scheme is most favorable in overcoming the distortion of elements. This description leads to make the simulation continued to the final stage of the incremental forming. On the other hand, the Lagrangian description as well as the original ALE description makes the elements much distorted and the analysis is stopped long before arriving at the final shape of deformation.

• Journal of the Korean Society of Safety
• /
• v.12 no.4
• /
• pp.214-219
• /
• 1997

The mechanical seals, which are installed in rotating machines like pump and compressor, are generally used as sealing devices in the many fields of industries. The failure of mechanical seals such as leakage, crack, breakage, fast and severe wear, excessive torque, and squeaking results in big problems. To identify abnormal phenomena on mechanical seals and to propose the proper monitoring parameter for the failure of mechanical seals, sliding wear experiments were conducted. Acoustic emission, torque, and temperature were measured during experiments. Optical microstructure was observed for the wear processing after every 10 minute sliding at rotation speed of 1750 rpm and scanning electron microscopy was also observed. Except for the initial part of every experiment, the variation of acoustic emission was well coincided with torque variation during the experiments. This study concludes that acoustic emission and torque are proper monitoring parameters for the failure of mechanical seals. The intensity of acoustic emission signals is measured in root mean square voltage. Temperature of sealing face will be used as a parallel parameter for increasing the reliability of monitoring system.

• The tire
• /
• s.69
• /
• pp.12-16
• /
• 1977

타이어의 실노면상에서의 트랙션성능을 측정, 평가하는것은 자동차의 발진, 가속, 제동 및 시회성능의 점으로브터 중요하면 이것을 측정하기 위해서 타이어 트랙션시험차를 개발했다. 이시험차는 타이어의트랙션성능을 미끄럼율과제동, 구동계수의 관계, 횡화각과 사이드포오스계수, 어라이닝토루크의 관계로 측정되는 특장을 갖는다. 이시험차를 이용해서, 건조및 습윤아스팔트노상과 설노상에서의 트랙션성능에 대한 타이어트랫드의 기본적 페턴의영향을 측정한 결과, 다음과 같은 지견을 얻었다. (1)도로의 상태의 상위에 의한 타이어트랙션 성능은 건조상태에선 습윤상태보다 크며 노설상에선 전양자보다 훨씬 작다. (2)트랫드의 종방향의 구본수의 영향에 대해선 여하한 노면상태에서든 구본수가 증가한만큼 트랙션성능은 증가하나 어느구본수에선 포화하는 경향이 있다. (3)설노상에서의 트랫드의 구각도에 대해서는 구의각도가 타이어의 진행방향에 대해서 직각의 페턴이 좋다고 할 수 있다.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.47 no.4
• /
• pp.28-34
• /
• 2010

In this paper, we proposed an algorithm for utilizing visual information for non-contact predicting method of friction coefficient. Coefficient of friction is very important in driving on road and traversing over obstacle. Our algorithm is based on terrain classification for visual image. The proposed method, non-contacting approach, has advantage over other methods that extract material characteristic of road by sensors contacting road surface. This method is composed of learning group(experiment, grouping material) and predicting friction coefficient group(Bayesian classification prediction function). Every group include previous work of vision. Advantage of our algorithm before entering such terrain can be very useful for avoiding slippery areas. We make experiment on measurement of friction coefficient of terrain. This result is utilized real friction coefficient as prediction method. We show error between real friction coefficient and predicted friction coefficient for performance evaluation of our algorithm.