• International Journal of Highway Engineering
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• v.3 no.2 s.8
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• pp.113-121
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• 2001

Among the currently available binder specifications, Superpave Performance Grade asphalt specification is regarded as a superior specification on its theoretical background as well as pavement performance relationship. Many difficulties are expected; however, for Superpave implementation in Korea because of heavy burden of equipment cost as well as lack of trained personnel in asphalt industry, which may too much barrier to overcome in Korean situation. As an effort to improve qualify of asphalt binder, recently, people discuss about a possibility of constituting a performance-based asphalt specification using rather easy-to-measure asphalt properties. The objective of this paper is to determine the possibility of constituting a performance-based asphalt specification using an empirical asphalt properties, such as penetration ring and ball softening point rather than using fundamental properties of asphalt. Nine straight asphalts, that covers entire straight asphalt from all Korean refineries, and eighteen modified asphalts that were modified from two modifiers were included in the study. An analysis was made through a comparison between empirical properties and Superpave PG criteria. This study concluded that it may possible to constitute a pseudo-Superpave-like specification using an empirical asphalt properties as a specification criteria. Therefore, more systematic research is needed to constitute the asphalt specification.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.123-134
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• 1993

This study was deviced to apply fuzzy concepts to pavement serviceability evaluation. An evaluation model was developed based on workmanship of pavement during construction, external load on pavement and current distress level. Five rating fuzzy sets, three weight fuzzy sets were developed based on the concept that the most appropriate balance was achieved in Gd which was established for grading the fuzzy overall rating results. Evaluation criteria and corresponding fuzzy rating scale were suggested. A computer program for evaluating serviceability based on the criteria was developed. The program was operated by simply typing in input data on each question and producing output as Gd on the screen. lt was possible to estimate the pavement serviceability level well using this fuzzy-set-based approach.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6A
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• pp.597-605
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• 2009

The safety of expressway bridges was estimated by checking the external condition rank based on the nondestructive inspection and material test and by measuring load carrying capacity based on the result of load test. Although the load carrying capacity of the bridges was clearly low compared to the design standard, it was examined that many of the bridges have good external condition rank relatively. Also, it can be assured that load carrying capacity shows a considerable difference according to various condition even though the bridges have similar construction year and a structural type. Therefore, this study showed various problems of the current safety measurement of expressway bridges by considering the status of the expressway bridges, external condition rank, and method of safety diagnosis and repair, rehabilitation for maintenance. Based on the existing data of over 400 expressway bridges, the load carrying capacity was analyzed quantitatively considering bridge type, serviced life, design live load, external condition rank and traffic count as variables. The result of this study will be expected to provide the basic information for a reasonable safety assessment of expressway bridge.

• International Journal of Highway Engineering
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• v.7 no.1 s.23
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• pp.63-71
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• 2005

Asphalt binder grading is to specify quality of asphalt binders relating to pavement performance in orderly manner, and provides the necessary information in selecting the appropriate asphalt binder for the hot mix design. For this purpose, United States has developed the PG-grading in 1995 and is implementing in practice. Recently, this American PG-grading system has been accepted as the domestic binder grading specification. However, the Asian (including Japan and China) and the most European countries are still use the traditional penetration and viscosity specification. The goal of this study lies in analysing the American PG-grading for its justification. As the result, the serious errors are found, and thus, to eliminate the errors, the more precise binder grading equation is introduced, Credibility of this study is checked by predicting the literature rut data with the equations mentioned. The prediction result are validating the claimes made in this study.

• 한국도로학회:학술대회논문집
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• 2003.10a
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• pp.229-234
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• 2003

• International Journal of Highway Engineering
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• v.3 no.2 s.8
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• pp.91-102
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• 2001

On the basis of several experiments peformed, Bahia et al. (1998) concluded that the current Superpave PG-grading system failed to characterize grading specification of fill modified binders. This conclusion motivates us to investigate the correct grating system suited for modified asphalt binders. The main concept of this development is originated from the relationship between rut depth and binder properties at high temperatures. A new grading system for modified asphalt binders suggested here somewhat resembles to the unmodified binder grading one developed by Huh et al. (2000). Thus, this investigation will provide a unified single theoretical equation of high temperature grading that can apply both to modified and unmodified binders, and will check its effectiveness with the laboratory and the field rut data reported by independent studies. Successful results observed may allow to construction of a correct grading system in the near future.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.162-165
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• 2010

합리적인 교량 대안선정을 위해서는 설계 시 경제성, 경관성, 안전성 및 기능성, 유지관리 용이성, 시공성 등 다양한 속성을 고려하여야 한다. 이 중 경제성은 초기비용뿐만 아니라 공용수명에 걸쳐 발생하는 유지관리비용, 보수 보강비용, 해체 폐기비용 등의 합인 총 생애주기비용에 대해 최소의 비용으로 최상의 가치를 창출하도록 하여야 한다. 본 연구에서는 건설계획과정에서 대표적으로 고려될 수 있는 대안으로 세 가지 교량 형식(강상자형교, 소수주형교, PSC-I형 거더교)을 대상구조물로 선정하고 교량의 공용수명은 상태등급곡선으로부터 추정한 내하율 곡선을 사용하여 산정하였다. LCC최적설계를 위해 설계변수, 제약조건, 목적함수를 구성하였고, 총 생애주기비용을 공용수명으로 나눈 연간생애주기비용을 사용하여 하여 합리적인 교량의 경제성 분석을 수행하였다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.82-88
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• 2012

The usage of recycling agent is the most effective way of enhancing the performance of recycled asphalt pavement. Generally, many countries accepted these recycling agents retarding the various types of cracks resulted in binder aging. Contrary to such general tendency, recycling agents are used as very small amount in domestic recycling plant. The main reason of this is relatively high price of recycling agent. Even though agent price is high, agent can be a effective and economical way of alternative in asphalt recycling. In this study, penetration and softning point test performed by using RTFO(Rolling Thin Film Oven) aged binder. And, PG(Performance Grade) at high temperature, fatigue and MSCR(Multi Stress Creep and Recovery) tests exercised. The oil type agent is worked well to retrieving target penetration number. In PG test, $G^*/sin{\delta}$ of agents identically showed high value and polymer type agent is good at recovery value.

• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.46.2-46.2
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• 2010

아스팔트 포장의 공용성능 행장을 위해 널리 사용되고 있는 폴리머 개질 아스팔트(PMA)는 높은 생산온도와 다짐온도로 인해 생산 시 연료 소비가 많고 시공관리가 어려운 단점을 가지고 있다. 이에 중온형 아스팔트 기술을 접목하여 고온에서의 아스팔트 점도를 낮춤으로써 이와 같은 문제점을 해결하고자 하였다. 바인더의 전반적 공용성능 향상을 위해서 폴리머 (SBR)와 작업성 개선을 위해 Wax 및 기타 첨가제를 혼합하여 아스팔트 바인더를 제조하였으며, 실험결과 PG 82-22의 높은 공용등급의 바인더를 얻었으며, 생산 및 시공온도는 기존의 PMA 아스팔트와 달리 일반 스트레이트아스팔트와 비슷한 수준을 확보하였다. 이를 이용한 아스팔트 혼합물의 공용 성능 면에서도 PMA개질 아스팔트와 비슷한 수준을 나타내었다.

• Journal of Korea Water Resources Association
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• v.45 no.11
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• pp.1131-1141
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• 2012

In this study, factors that influence water supply capacities of dams are extracted using factor analysis, and multiple regression equations for estimating water supply capacities of dams are developed using the analysis results. Twenty-one multi-purpose dams and twelve Municipal and Industrial (M&I) water supply dams are selected for case studies, and eight variables influencing water supply capacities of dams, namely: watershed area, inflow, effective reservoir storage, grade on amount of M&I water supply, grade on amount of agricultural water supply, grade on amount of in-stream flow supply, grade on river administration, and grade on average rainfall, are determined. Two case studies for multi-purpose dams and M&I water supply dams are performed, employing factor analysis, respectively. For the two cases, preliminary tests, such as reviewing matrix of correlation coefficient, Bartlett's test of sphericity, and Kaiser-Meyer-Olkin (KMO) test, are conducted to evaluate the suitability of the variables for factor analysis. In case of multi-purpose dams, variables are grouped into three factors; M&I water supply dams, two factors. The factors are rotated using Varimax method, and then factor loading of each variable is computed. The results show that the variables influencing water supply capacities of dams are reasonably selected and appropriately grouped into factors. In addition, multiple regression equations for predicting the amounts of annual water supply of dams are established using the factor scores as explanatory variables, it is identified that the models' accuracies are high, and their applications to determining effective storage capacity of a dam during dam planning and design steps are presented. Consequently, it is thought that the variables and factors are useful for dam planning and dam design.