• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.4
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• pp.45-51
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• 2009

The paper presents the economic analysis of optimized-rehabilitation area method considered as one of the preventive maintenance methods in asphalt concrete pavement. The optimized-rehabilitation area was selected based on the analysis of traffic lane characteristics. The main concept of the selected method was to minimize the maintenance cost. The effective width of traffic lane in this method was 70 cm of each wheel path. According to the traffic survey conducted in this research, more than 95% of vehicles passed within the width of each wheel path. The new preventive optimized-rehabilitation area method showed less maintenance cost than the conventional overlay. In addition, traffic congestions and the user cost can be reduced. The research results revealed that the total maintenance cost was reduced by 35% by using the new method compare to the conventional one.

• International Journal of Highway Engineering
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• v.12 no.2
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• pp.123-127
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• 2010

In this study, the profiles of optimized rehabilitated section was measured by a lightweight inertial profiler, and pavement smoothness was evaluated. To analyze the repeatability of the used lightweight profiler, two repeatable measurements were conducted. The agreement between two repeatable measurements were evaluated by Cross-correlation function. Pavement smoothness of the optimized rehabilitated pavement section and existing area was compared in terms of International Roughness Index and Profilograh Index. In general, the pavement smoothness of the rehabilitated sections was not good compared to the existing pavement sections. The analysis results could be used for the evaluation of pavement smoothness of the optimized rehabilitated pavement sections.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4D
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• pp.565-569
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• 2011

This paper presents minimum area repair method that is one of the preventive maintenance techniques in asphalt concrete pavements. In this method, a 70cm-width as an effective repair zone was suggested considering the conventional longitudinal damages (rutting and fatigue cracking) in early stages. In addition, the repair zone can be readjusted according to the pavement damage levels. A field test bed was constructed to verify the adaptness for the repair method. Test results revealed that the minimum area repair method can be adopted as a preventive maintenance technique in flexible pavements to recover an appropriate serviceability level. The preventive maintenance method may be one of the major maintenance methods of flexible pavements with an appropriate application. It is also noted that the method may be a long term maintenance cost effective and pavement life ensuring one.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.229-237
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• 2005

통신용 지하 관로는 대부분 내경 100mm인 PVC 재질로 되어 있으며, 지하에 매설한 후 또는 관로를 사용하기 전에 관로 상태의 정상 유무를 확인할 목적으로 맨드릴(직경 90mm)을 이용한 선통 검사로 정상 관로와 불량 관로를 판단 하였다. 그러나 이러한 방법으로는 조사 대상 관로의 불량 원인을 밝힐 수 없을 뿐 아니라, 복수 개소의 불량 지점을 확인하는 것이 불가능하여 관로 보수나 사용을 위한 기본적인 관로 정보를 제공할 수 없었다. 이러한 문제를 해결하기 위해 디지털 관로 조사장비를 개발하였으며, 관로 내부를 따라 관로 카메라를 이동시키면서 관로 내부의 변형 상태를 실시간으로 확인하거나, 관로 벽에 조사된 레이저 빔 영상을 검출하여 관로 단면의 최소 직경을 측정할 수도 있다. 또한, 디지털 맨드릴은 1mm 간격으로 관로의 내경을 측정할 수 있는 게이지가 설치되어 있어, 실시간으로 관로 단면의 최소 직경을 측정할 수 있어 조사 관로의 전반적인 변형 정도를 모니터링 할 수 있다. 이러한 디지털 관로 조사장비를 이용하여 신설 관로의 시공품질을 측정하거나, 기존 관로의 상태를 객관적이고 정확하게 파악하여 관로 상태에 따른 케이블 포설 계획을 수립할 수 있으며, 불량 관로 보수를 위한 정확한 자료를 제공하여 유지관리의 효율성을 높일 수 있다.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.159-169
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• 2007

In this paper, a PMS(Pavement Management System) is presented for the public agency who wish to execute rational repair by referring to asset management information regarding road pavement. The aim of the paper is to provide the decision makers with the planning information regarding maintenance strategies for efficient road pavement management. We found that life cycle cost can be minimized and repair cost in each year fluctuates when repeating repair at the IRI management level. The validity of PMS application presented in this paper is investigated through case studies for conducted for 22 national highway road sections in Korea.

• International Journal of Highway Engineering
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• v.7 no.3 s.25
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• pp.1-10
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• 2005

In this study, accelerated pavement tester(APT) was performed on long-life asphalt pavements that can save maintenance and user costs by increasing the design life twice longer than conventional asphalt pavements. Basic material testings are first conducted on a high modulus base(HMB) mixture developed in this study. Four different pavement sections including thin and thick conventional and thin and thick HMB courses are constructed to compare the load-carrying capacities and to investigate the fatigue and rutting performances using an accelerated pavement tester. Tensile strain values at the bottom of base courses under the various loading levels are measured. The tensile strain values of the HMB sections are lower than those of the conventional sections. It is observed from the APT performed on the thin pavement sections that no significant cracks are developed up to the 180,000 cycles of a wheel load. In terms of rutting, only 3mm of rutting is developed in the thick HMB section while 5.3mm of rutting is developed in the thick conventional section at the 90,000 cycles of the wheel load. The HMB material developed in this study can be successfully used in the long-life asphalt pavements because of its excellent fatigue and rutting performances. It is estimated from a series of structural analysis that the use of the HMB material instead of the conventional base materials may reduce the asphalt thickness at least 5cm because of its better load-carrying capacity.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.475-478
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• 2007

The major distresses in asphalt concrete pavement are rutting and fatigue cracking. Once the distresses are observed on pavement surface, an appropriate rehabilitation method should be found. Usually, asphalt patching or overlay methods are used to improve the pavement performance. The research presents the fundamental study on effective longitudinal rehabilitation methods for asphalt concrete pavements. The rehabilitation method will be applied to rutting that is occurred asphalt Pavement surface course and longitudinal cracking or fatigue cracking with light to moderate distress levels.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.5
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• pp.452-460
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• 2008

Anti-foaming agents and foam fences have been used to remove the foam at the outfall of power plants, but there are some problems as consumption of maintenance costs and insufficiency of effect. Therefore, development of the methods how to remove the foam by stable coastal structure has been required. In this study, numerical simulation of air entrainment was carried out to design the submerged outlet structure for reducing foam using curtain walls. The air entrainment rate and the discharge of entrained air change according to the shape of weir and curtain wall. Hence, it is necessary to design the optimum section through comparison of each case. The optimum section which has the maximum rate of foam reduction was determined by the simulation results. In addition, it was found that the flow velocity at the submerged outlet is to be smaller than 1 m/s and the submerged depth of curtain wall is to be taller than height of the submerged outlet section.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.310-310
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• 2017

홍수추적 모형의 적절성을 결정하는 중요한 요소 중 하나는 모형의 매개변수이다. 특히 자연하천에 관한 부정류 계산모형의 매개변수인 조도계수는 하상재료의 특성에 따라 좌우되는 표피마찰뿐만 아니라 하상의 굴곡 등 단면형의 변화에 따른 형상손실 및 하천의 사행에 따른 손실 효과 등을 포괄적으로 내포하고 있기 때문에 모든 하천구간에 대하여 일반적으로 적용할 수 있는 조도계수의 값을 하나로 결정하기는 어렵다. 또한 조도계수는 흐름조건, 즉 유량 또는 수위의 변화에 따른 가변성을 갖고 있기 때문에, 흐름이 시간 및 공간적으로 변화하는 부정류 계산모형에 있어서는 더욱 그러하다. 그러므로 본 연구에서는 조도계수의 가변성과 다수 지점의 관측치를 고려한 모형보정의 결과로부터 얻은 파레토 최적화와 최소최대 후회도 방법(Minimax regret approach, MRA)을 결합하여 부정류 계산모형의 안정적인 매개변수를 선정할 수 있는 방법을 제안하였다. 여러 지점의 관측치를 고려한 모형의 보정은 다목적 최적화 문제로서, 여러 지점에 대한 가중치를 결합하여 얻은 하나의 목적함수에 대하여 여러 번의 개별 최적화를 수행함으로써 다수의 파레토 최적해들을 구할 수 있는 통합접근법을 적용하였다. 이때 유량에 따른 조도계수의 가변성을 나타내는 두 개의 매개변수로 구성된 관계식을 이용하여 두 구간에 대한 매개변수들을 모형의 추정 대상 매개변수로서 최적화하였다. 이 후 각기 다른 홍수사상에 대해 보정과 검증을 수행하였으며 각각에 대한 평가지표의 후회도를 정량화하였고 최종 안정적인 매개변수를 추정하기 위해 MRA를 이용하여 종합적인 순위를 도출하였다. MRA는 완전히 불확실한 의사결정 상황에서 유용한 방법으로 알려져 있는데 가장 나쁜 순위가 가장 좋은 것을 선택할 수 있게 하는 보수적인 의사결정기법이다. 계산결과 추정된 모형의 가변조도계수와 그로부터 얻은 두 개 지점에서의 평가지표인 RMSE는 두 지점에 대한 가중치의 조합에 따라 선택되는 매개변수 값에 따라 달라짐을 알 수 있었다. 본 연구에서 제시한 방법은 수문 및 수리모형의 다수의 관측지점의 자료를 이용한 매개변수 산정문제에 있어서 안정적인 해를 도출할 수 있다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.196-205
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• 2017

In precast deck system, structural performance and serviceability are mostly determined by the connection methods between the precast decks. This study proposes precast deck system with asymmetric ribbed connection details using High Strength Fiber Reinforced Concrete(HSFRC) with filler. To verify the proposed method, the flexural performance experiment was carried out with variation of joint cross section type and splice rebar details. From the test results, regardless of joint details, spliced tensile rebars of specimens were deformed to yielding strain level. Also, all types of specimens resulted in sufficient flexural performance. These test results show that the minimum lap splice length specified in current Korea Highway Bridge Design Code is conservative for precast deck joint using HSFRC. Therefore, splice details can be simplified and joint width can be reduced by using HSFRC with filler between the precast decks, and the proposed precast deck systems can be applied to the connection part of precast decks effectively.