• Wind and Structures
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• v.5 no.2_3_4
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• pp.257-266
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• 2002

In the recent years flow around bridges are investigated using computer modeling. Selvam (1998), Selvam and Bosch (1999), Frandsen and McRobie (1999) used finite element procedures. Larsen and Walther (1997) used discrete vorticity procedure. The aeroelastic instability is a major criterion to be checked for long span bridges. If the wind speed experienced by a bridge is greater than the critical wind speed for flutter, then the bridge fails due to aeroelastic instability. Larsen and Walther (1997) computed the critical velocity for flutter using discrete vortex method similar to wind tunnel procedures. In this work, the critical velocity for flutter will be calculated directly (free oscillation procedure) similar to the approaches reported by Selvam et al. (1998). It is expected that the computational time required to compute the critical velocity using this approach may be much shorter than the traditional approach. The computed critical flutter velocity of 69 m/s is in reasonable comparison with wind tunnel measurement. The no flutter and flutter conditions are illustrated using the bridge response in time.

• Journal of Environmental Health Sciences
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• v.27 no.4
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• pp.99-105
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• 2001

도로교통소음은 많은 지역에 산재해 있으며 특히 주도로변에 거주하는 사람들에게 환경과 관련하여 매우 중요하다. 도로교통으로부터 소음수준을 계산하는데 몇가지 다른 방법들이 이용되고 있다. 이 방법들은 계산방법과 그래프식 그리고 컴퓨터 모델링 기술 등이다. 교통과 교통소음의 영향으로부터 소음을 계산하는 간단한 기술의 예측방법은 여기에 나타내었다. 이 TNS (traffic Noise Screening) 방법은 서로 다른 도로유형에 대한 일련의 도로교통소음레벨의 예측그래프로 전개된 것이다. 이 그래프는 Federal Highway Administration (FHWA) STAMINA 2.0을 이용하여 다양한 시나리오에 대한 소음 예측모델을 계산한 결과를 기초하였다. TNS에 도로의 기하학적 형태, 교통량 주행속도 그리고 도로중앙선의 거리등의 데이터를 입력시킨다. TNS 그래프는 소음영향과 연관된 교통소음예측에서 사용하는 경우 교통소음레벨의 계산을 쉽게 한다. 이 TNS 방법은 STAMINA 2.0과 같은 상세 모델링을 대신하지는 못하지만 상세 모델을 필요로 할 때 도움을 주는 도구이다 만약 소음계산들이 중요하거나 또는 시나리오가 보다 복잡하고 부가된다면 보다 상세한 모델링이 수행되어져 스크린 결과들이 나타난다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.1-4
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• 2008

Prediction models currently being used for road traffic noise in apartment are equation of NIER, HW-NOISE of Korea Expressway Corporation, FHWA of United States, CRTN of United Kingdom, NMPB of France, ASJ RTN-Model 2003 of Japan and ISO 9613-1, 2 as a international standard. ISO 9613 species an engineering method for calculating the attenuation of sound during propagation outdoors in order to predict the levels of environmental noise at a distance from a variety of sources. This study, prior to investigation of every prediction methods listed above, aims to examine the model internationally standardized and to establish a reference for the prediction of road traffic noise in apartment.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.537-544
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• 2009

Several domestic and foreign design methods for rock socketed drilled shafts were introduced in this study. In order to verify these design methods, the results of field pile load tests were compared with predicted capacities using them. Based on this study, AASHTO(1996) and FHWA(1999) design methods tend to underestimate, and CFEM(2006) and NAVFAC(1982) tend to overestimate. The difference between the predicted and measured values was caused by reflecting different rock socket geometry and also different rock properties in each design method.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.625-629
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• 2010

암거 수리설계는 상류부의 수위를 과다하게 상승시키지 않는 상태에서 안전하게 계획홍수량을 하류로 소통시킬 수 있도록 최적의 단면을 결정하는 것이다. 현재 국내 암거 설계는 한국도로공사(1991)에서 발표한 "도로배수계획"을 이용하고 있는데, 이는 주로 미국도로성(FHWA)에서 발표한 설계기법을 따른 것이며, 이 기법은 설계항목과 관련되는 설계유량과 지배단면을 결정하여 시행오차적인 방법으로 계획 상류부 수심을 산정하는 순서로 진행된다. 상류부 수심을 결정하기 위해서 미국도로성의 기법은 계산도표를 이용하여 손실 수두와 한계수심을 산정한다. 그러나 계산도표를 이용하여 설계할 경우 주관적인 오차가 생길 수 있으며 전산해석에 있어서도 큰 장애요인이 될 수 있다. 본 연구에서는 기존 연구에서 기술된 암거 설계법을 전반적으로 재검토하여 일부 수식 전개 과정에서 발생한 오류를 수정하고, 암거의 규격 산정 시 암거의 형상을 미리 결정하여 암거 프로그램 개발 시 효율적일 것으로 판단되는 새로운 방법을 개발하였다.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.541-548
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• 2002

This paper presents the results of stability analyses on soil-reinforced segmental retaining walls in a tiered arrangement. As-built design sections of four different walls were analyzed within the context of the limit equilibrium-based current design guidelines. The appropriateness of the original designs were then evaluated. Slope stability analyses against the compound failure mode, which Is frequently Ignored during design, were additionally peformed based on the method recommended by FHWA design guideline. The results indicate that the as-built designs of most of the walls examined do not meet the minimum factors of safety for the external and internal stabilities, and for the compound failure mode. The implications of the findings from this study are discussed.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.18-24
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• 2022

State highway agencies (SHAs) typically apply a competitive procurement procedure to select contractors for their design-bid-build projects. Since the level of competition affects construction bid prices and project outcomes, the Federal Highway Agency (FHWA) suggests SHAs seek ways to improve competition among contractors continuously. However, they rarely conduct an empirical assessment of the current competition level necessary to identify room for improvement. Besides the number of bidders on a project, other factors such as winning or losing rates among the contractors in previous projects can also indicate the degree of competition; only a few contractors may have won the majority of the projects in a specific region. However, few studies have investigated such factors. This paper proposes a network analysis-based approach to evaluating contractor competition levels of highway projects using historical bid tabulation data. The proposed method provides insights into overall competition levels, the determination of competitive contractors, and winning rate distribution among contractors.

• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.263-272
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• 2019

This paper describes the results of bearing capacity using field loading test of pile, in order to extend the applicability of drilled shaft with mid-size, and the results were compared with the prediction results of design bearing capacity by empirical formular. The static load test result showed that the allowable bearing capacity of high pile strength was about 2.4 times higher than that of low pile strength. The dynamic load test result showed that the allowable bearing capacity of high pile strength was about 1.4 times~1.5 times higher than that of low pile strength. The comparison result of allowable bearing capacity between static and dynamic load test showed that the difference of allowable load ranged from 3% to 6% under the same settlement conditions. As a result of comparing the ultimate bearing capacity by load test and design bearing capacity, it was found that the FHWA proposed equation could be more reasonable than the other proposed equation in load sharing ratios of end bearing and skin friction.

• The Journal of the Korea Contents Association
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• v.10 no.11
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• pp.68-79
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• 2010

With the social infrastructure being deteriorated, there is a growing need to introduce the asset management to social infrastructure management in order to increase their value and save budget. Social infrastructure asset management is a new concept of facility management in response to these demands. It is defined as a procedure for collecting and analysing facility maintenance data and for making and practicing an economically optimized management plan. Detailed survey work of asset management business is analyzed in order to derive a strategy for asset management information. The contents of IIMM of New Zealand and the asset management definition of the FHWA of the United States, and representative facility management systems of Korea are analysed. The role between organizations and the relationship between business and organization were analyzed. Information required for asset management and for existing facility management systems is compared with business of asset management. In this thesis, three development strategies are suggested. The first one is to develop core business of asset management while excluding duplicated development. The second one is to divide system's structure into three layers. And the last one is to share information by interfacing asset management systems with existing facility management systems.

• Journal of the Korean Geosynthetics Society
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• v.19 no.1
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• pp.65-73
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• 2020

This study describes the evaluation results of pile length ratio and N value on the bearing capacity of drilled shafts in cohesionless soil. The bearing capacity ratio in Meyerhof's formula is affected only by the length ratio, and it is equally evaluated a sharing ratio of the end bearing capacity and the skin friction. NAVFAC's formula shows that the pile length influences both end bearing capacity and the skin friction, but pile length is also found to be a more influence factor on the end bearing capacity. Especially, it was found that the effect of pile length factor was larger than the effect of N value and pile diameter. FHWA's formula was evaluated to reflect the influence factor by skin friction more positively than other formulas at calculation the bearing capacity. It was also confirmed that the influence of the skin friction is larger when the ultimate bearing capacity is evaluated.