• Journal of the Korea Concrete Institute
• /
• v.13 no.4
• /
• pp.362-370
• /
• 2001

The internal or external restraint of thermal and dry shrinkage movements could thus generate tensile stresses in concrete pavement for early traffic opening. Restrained shrinkage and thermal stresses could produce microcracks in concrete which increase its permeability and accelerate its long-term deterioration under weathering and load effects. Fiber reinforced concrete is an effective approach to the control of microcrack and crack development under tensile stresses. This study aims at evaluation of the durability of high early strength concrete for early traffic opening and increase of service life. Three different types of regulated-set cement which recently has been used much in Korea were adopted. Fibers were added and their mixtures were compared with plain high early strength concrete mixture. The use of fibers increased durability performance of high early strength concrete using regulated-set cement than the corresponding plain mixtures.

• International Journal of Highway Engineering
• /
• v.3 no.2 s.8
• /
• pp.123-130
• /
• 2001

This study was performed to enhance mechanical properties of high-early-strength concrete using regulated-set cement for early traffic opening with various mixtures. Restraint of moisture and thermal movements of concrete pavement in actual field conditions, by external or internal restraining factors, generates tensile stresses which introduce microcracks and thus reduce the mechanical properties of concrete. Fiber reinforcement of concrete is an effective approch to the control of microcrack and crack development under tensile stresses. Three different types of regulated-set cement which recently have been used in Korea and two different types of fiber were adopted. Fibers were added and their mixtures are compared with plain high-early-strength concrete mixture. From the test results, fiber reinforced concrete was increased mechanical properties of high-early-strength concrete using regulated-set cement than the plain concrete.

• Transportation Technology and Policy
• /
• v.8 no.5
• /
• pp.33-39
• /
• 2011

• 한국도로학회:학술대회논문집
• /
• 2006.10a
• /
• pp.83-88
• /
• 2006

• International Journal of Highway Engineering
• /
• v.13 no.1
• /
• pp.139-148
• /
• 2011

Asphalt concrete overlay method is used by general maintenance and rehabilitation of construction for aged concrete pavement in Korea. However, in case of the AC overlay method to extend service life of the existing concrete pavements, various distresses of reflection crack, pothole and rutting are the typical problems of the asphalt overlay on existing concrete pavement since it has different physical characteristics between asphalt overlay and existing concrete pavement. To achieve this, application of concrete overlay method is required instead of AC overlay method. Concrete overlay method has advantages that can reduce maintenance cycle and costs since it has excellent bearing value for heavy vehicles and no rutting. However, technical problems of detour road construction, traffic control and other disadvantages happened by long curing time. Thus, in this study and experimental research were launched to evaluate the workability, durability and resistance against environmental loading of Very Rapid Hardening Acrylic Polymer Modified Concrete(VRH-APMC) for application of bonded concrete overlay method. Test results showed that the compressive and bond strength were exceed 21MPa and 1.4MPa of target strength after four hours for rapid traffic opening properties. And tests of resistance against environmental loading results showed that VRH-APMC secured excellent durability. Thus, it was known that VRH-APMC was suitable material for large scale bonded concrete overlay method, and it was possible to use maintenance and rehabilitation method which needs enough workability and rapid traffic opening.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.4D
• /
• pp.555-564
• /
• 2011

More than sixty percentages of the highway constructed by concrete pavements in South Korea and over half of the concrete pavements were twenty years or older. The most of South Korea road is hard to provide a bypass in conditions of network of roads. Asphalt concrete overlay has been used for the overlay of aged concrete pavement. However, the cost of maintenance and rehabilitation in an asphalt overlay is expensive by early damage. Therefore, bonded concrete overlay was recently attempted in South Korea as an alterative method of rehabilitation for aged concrete pavement. Hence, it needed to investigate the factors to find performance of the bonded concrete overlay life. However, there is no performance data of the concrete overlay in South Korea. This study was to make a database of an affecting of the pavement life and draws statistical analysis of the performance data on the LTPP (Long Term Pavement Performance) database of U.S.A.

• 한국방재학회:학술대회논문집
• /
• 2007.02a
• /
• pp.117-120
• /
• 2007

The main purpose of this paper is to introduce the early traffic opening-capable continuous multi-layer asphalt pavement maintenance method using electric arc furnace slag aggregate and emulsified asphalt to the actual construction sites. As well known, the previous surface treatment method of emulsified asphalt mixture have various shortcomings such as long work-time, traffic congestions, plastic deformation and poor evenness. Thus, the proposed method has enabled tile early traffic opening by utilizing the optimized emulsified asphalt after consideration of the climate and road conditions in Korea. The application of the electric furnace slag with $6\;{\sim}\;18\;mm$ thickness is helpful to become a environment-friendly construction method. And also, it has been improved enough to accommodate night-time works of mechanized construction activities for wearing course and control course.

• International Journal of Highway Engineering
• /
• v.13 no.1
• /
• pp.207-221
• /
• 2011

More than sixty percentage of highway in South Korea were constructed by concrete pavements and more than half of the concrete pavements were twenty years or older. The most of highway have difficulty in providing detour due to the traffic and road condition of South Korea. So far, asphalt concrete has been used for the overlay of aged cement concrete pavement. However, the frequent early damage and maintenance of typical asphalt overlay due to repetitive maintenance causes inconvenience of road users and expensive costs. It is necessary to investigate the factors affecting the performance of asphalt concrete overlay to improve the performance of asphalt overlay. However, the performance data of asphalt concrete overlay in South Korea does not exist. In this research, to investigate on the factors affecting the life of asphalt concrete overlay was attempted based on statistical analysis of the performance data of asphalt concrete overlay included in LTPP (Long-Term Pavement Performance) Database of U.S.A.

• Proceedings of the KOR-BRONCHOESO Conference
• /
• 2003.09a
• /
• pp.110-110
• /
• 2003

후두기관외상은 두경부 부위의 다른 외상에 비해 흔하지 않은데, 이는 연골의 유연성과 후두의 가동성, 후두가 하악과 흉골사이에 위치하여 외상시 보호 받게 되는 해부학적 특성에 기인한다. 그러나, 후두는 호흡과 발성에 중요한 기관으로 조기 진단과 정확한 평가, 적절한 치료를 못할 경우 생명을 위협 할 수 있고 삶의 질에 지대한 영향을 줄 수 있다. 이에 저자들은 급성 후두기관손상으로 수술적 치료를 받은 환자를 대상으로 손상 기전 및 임상 양상, 손상부위, 손상 정도 치료 등을 알아보고 향후 치료에 도움을 얻고자 하였다. 1996년부터 2003년까지 급성 후두기관 손상으로 수술적 치료를 받은 10명을 대상으로 후향적으로 조사를 하였다. 손상정도는 Schaefer의 분류를 따랐으며 술후 결과는 발성과 기도유지로 평가하였다. 발성의 경우 수상전과 동일하거나 유사할 경우 성공(good)으로, 수상전과는 다르지만 기능을 하는 경우는 양호(fair)로, 거의 음성이 나지 않거나 알아들을 수 없는 경우 불량(poor)로 분류하였고, 기도유지는 수상전과 동일하거나 유사할 경우 성공(good)으로, 경한 흡인이나 운동 유발성 호흡곤란이 있는 경우(fair)로 발관이 되지 않는 경우를 불량(poor)으로 분류하였다. 남녀 성비는 8대 2였고 30～40대가 4명으로 가장 많았다. 손상의 원인은 둔상인 경우(4예) 교통사고가 2례, cloth line 손상 2례, 관통상(6례)는 모두 칼에 의한 좌상이었다 증상은 피하기종이 9례, 애성이 7례, 호흡 곤란이 6례로 많았으며 손상부위는 갑상연골 골절이 5례(50％), 기도손상과 갑상선 손상이 각각 4례에서 관찰되었다. 그 외에도 윤상 연골 골절과 윤상갑상막 손상 등이 관찰되었다. 또한 점막 손상이 7례에서 관찰되었다. 성대마비는 내원시 4례에서 관찰되었다 치료는 수상 후 조기수술을 시행하였고 수상 부위를 개방하여 손상된 연조직을 일차 봉합하거나, 골절을 정복 고정하였고 3례에서 스텐트를 삽입하였다. 술후 기도유지는 모두 성공적이었고 발성기능은 6례에서 성공(good)적이었고 4례에서 양호(fair)의 결과를 보였다. 양호의 결과를 보인 모든 예가 내원시 성대 움직임의 마비나 저하를 보인 예였다. 급성 후두기관손상환자에서 조기 진단과 적절한 수술적 치료는 환자의 생명을 유지시키고 술후 발성 지능의 보존에 양호한 결과를 보였다.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.13 no.3 s.55
• /
• pp.173-180
• /
• 2009

Very-early strength latex-modified concrete(below ; VES-LMC) was developed for possible early-opening-to-traffic after overlay of bridge deck concrete. The purpose of this study is to analyze the cause of map, transverse and longitudinal cracking in VES-LMC and to provide a control method for minimizing occurrence of cracking. The proposed prevention method against map and transverse cracking was verified by field data. VES cement was modified as the unit cement content was reduced from 390kg/$m^3$ to 360kg/$m^3$. The maximum size of coarse aggregate was increased from 13mm to 19mm. The wire mesh and steel fiber were adopted in concrete mixture. From the results, the proposed prevention method against map and transverse cracking was verified since structural cracking was not occurred until 3 years after overlay.