Parameter-setting-free algorithm to determine the individual sound power levels of noise sources

문성호,Mun, Sungho Korean Society of Road Engineers 2018 한국도로학회논문집 Vol.20 No.3

PURPOSES : We propose a parameter-setting-free harmony-search (PSF-HS) algorithm to determine the individual sound power levels of noise sources in the cases of industrial or road noise environment. METHODS :In terms of using methods, we use PSF-HS algorithm because the optimization parameters cannot be fixed through finding the global minimum. RESULTS:We found that the main advantage of the PSF-HS heuristic algorithm is its ability to find the best global solution of individual sound power levels through a nonlinear complex function, even though the parameters of the original harmony-search (HS) algorithm are not fixed. In an industrial and road environment, high noise exposure is harmful, and can cause nonauditory effects that endanger worker and passenger safety. This study proposes the PSF-HS algorithm for determining the PWL of an individual machine (or vehicle), which is a useful technique for industrial (or road) engineers to identify the dominant noise source in the workplace (or road field testing case). CONCLUSIONS : This study focuses on providing an efficient method to determine sound power levels (PWLs) and the dominant noise source while multiple machines (or vehicles) are operating, for comparison with the results of previous research. This paper can extend the state-of-the-art in a heuristic search algorithm to determine the individual PWLs of machines as well as loud machines (or vehicles), based on the parameter-setting-free harmony-search (PSF-HS) algorithm. This algorithm can be applied into determining the dominant noise sources of several vehicles in the cases of road cross sections and congested housing complex.

Analysis of Truck involved Accidents on Freeways

양충헌,손영태,Yang, Choon-Heon,Son, Young-Tae Korean Society of Road Engineers 2008 한국도로학회논문집 Vol.10 No.2

트럭은 상대적으로 낮은 운송비용과 그 운영의 탄력성 때문에 화물 운송에 가장 널리 이용되는 교통 수단이다. 그러나 전체 교통량에서 트럭교통이 차지하는 비율이 높은 곳에서는 심각한 안전 문제를 일으킬 수 있다. 트럭사고는 다른 차량간의 사고보다 더 심각한 부상이나 사상자를 야기 시킬 수 있다. 따라서, 트럭 교통과 관련된 안전 문제는 교통 시스템을 운영, 관리하는 공공부분과 이러한 시스템을 이용하는 일반 운전자에게 있어 중요한 문제이다. 본 연구에서는 트럭관련 사고 자료를 이용하여 교통 조건에 따른 사고 형태를 조사하고 통계기법을 사용하여 현장에서 조사된 사고 요인들 중 어떤 것이 가장 큰 트럭관련 사고 요인인지를 분석한다. 이 연구를 위한 자료는 TASAS의 database를 이용하였다. 중요 사고 요인이 분석이 되면, 효과적이고 효율적인 트럭 관리 전략에 대해 논의해 볼 수 있다. Trucking is the most frequently used mode for freight movement due to relatively lower shipping costs and its operational flexibility. However, truck traffic can contribute to serious safety problems where they occupy high percentage of the total traffic. Heavy truck crashes arc more likely to result in serious injuries and fatalities than are crashes involving light vehicles. Therefore, safety issues for truck traffic are very significant both for public agencies and for general travelers. The objective of our study is to find truck-involved accident patterns according to traffic conditions and main factors as well as to find the most critical factor through conventional statistical techniques. A vailable data were obtained from TASAS (Traffic Accident Surveillance and Analysis System). Once critical factors are identified, effective and efficient truck management strategies can be discussed.

Evaluation of Warm Mix Asphalt Mixtures with Foaming Technology and Additives Using New Simple Performance Testing Equipment

김용주,임수혁,이호신,황성도,Kim, Yong-Joo,Im, Soo-Hyok,Lee, David,Hwang, Sung-Do Korean Society of Road Engineers 2008 한국도로학회논문집 Vol.10 No.4

To produce asphalt mixtures at temperature significantly below $135^{\circ}C$, called "Warm Mix Asphalt (WMA)", new technologies are currently being developed worldwide. To produce WMA mixtures in this research, foaming technology is adopted to effectively disperse asphalt binder at lower temperature than hot mix asphalt (HMA) in the field. The main objectives of this study are to develop WMA process using foaming technology (WMA-foam) and evaluate its performance characteristics under various temperatures and loading conditions. WMA-foam mixtures were produced by injecting PO 64-22 foamed asphalt into warm aggregates whereas WMA mixtures were produced by adding PO 64-22 asphalt (without foaming) in the warm aggregates. Both dynamic modulus and flow number of WMA-foam mixtures were higher than those of WMA mixtures. Based on the limited dynamic modulus and repeated load test results, it is concluded that the WMA-foam mixtures using warm aggregates at $100^{\circ}C$ are more resistant to fatigue cracking and rutting than WMA mixtures. 최근에 $135^{\circ}C^{\circ}C$ 이하의 온도에서 생산되는 중온형 아스팔트 혼합물의 새로운 생산 기술이 전세계적으로 개발되고 있다. 본 연구에서는 가열 아스팔트보다 낮은 온도에서 아스팔트를 효과적으로 골재에 분산시켜 코팅할 수 있는 폼드 아스팔트 기술을 이용하여 중온형 아스팔트 혼합물을 생산하였으며, 최근 개발된 새로운 Simple Performance Testing 장비를 이용하여 다양한 온도와 하중조건 하에서 중온형 폼드 아스팔트 혼합물의 공용성 특성을 평가하였다. 중온형 폼드 아스팔트 혼합물은 FG 64-22의 아스팔트를 거품상태로 만들어 중온으로 가열된 골재에 뿌려서 제조하였으며, 중온형 아스팔트 혼합물은 중온의 골재에 FG 64-22의 아스팔트를 액상 상태로 첨가하여 제조하였다. 중온형 폼드 아스팔트 혼합물은 중온형 아스팔트 혼합물보다 높은 동탄성계수와 Flow Number를 나타내었다. 따라서, $100^{\circ}C$로 가열된 골재를 사용하여 생산된 중온형 폼드 아스팔트 혼합물은 중온형 아스팔트 혼합물에 비하여 피로균열 및 소성변형 저항에 우수한 것으로 평가되었다.

미국의 아스팔트기술연구소(NCAT)의 기술동향

Brown, Brown,Prowell, Prowell,Cooley, Cooley,Zhang, Zhang,Powell, Powell Korean Society of Road Engineers 2004 도로포장공학회지 Vol.6 No.4

Sensitivity Analysis of Load Trunsfer of Jointed Concrete Pavements Using 3-D Finite Element Model

썬런쥬안,임진선,정진훈,Sun, Ren-Juan,Lim, Jin-Sun,Jeong, Jin-Hoon Korean Society of Road Engineers 2008 한국도로학회논문집 Vol.10 No.2

Load transfer efficiency (LTE) reflects the structural performance of doweled and undoweled joints of Jointed Concrete Pavement (JCP). A 3-dimensional (3-D) model of JCP was built using ABAQUS software in this study. Three concrete slabs were placed on bonded sublayers composed of a base and subgrade. Spring elements were used to connect the adjacent slabs at joints. Different spring constants were input to the model to simulate different joint stiffness of the concrete pavement. The LTE of the joint increased with an increase of the spring constant. The effects of material properties and geometric shape on the behavior of JCP were analyzed using different elastic modulus and thickness of the slab and base in the modeling. The results showed the elastic modulus of the subgrade affected the behavior of the slab and LTE more than that of the base and the thickness of the slab and base. The effects of a negative temperature gradient on the behavior of the slab and LTE were more than that of positive and zero temperature gradients. Joints with low stiffness were more sensitive to the temperature gradient of the slab. 하중전달효율은 다웰이 설치되었거나 설치되지 않은 콘크리트포장 줄눈의 구조적 성능을 나타내기 위해 사용된다. ABAQUS 소프트웨어를 사용한 줄눈 콘크리트장의 3차원 모형이 본 연구를 통하여 구축되었다. 기층과 노상이 접착되어 구성된 하부층 위에 3개의 슬래브가 놓였으며, 스프링 요소를 사용하여 인접한 슬래브를 줄눈에서 연결하였다. 콘크리트포장의 다양한 줄눈강성을 모사하기 위하여 다양한 값의 스프링 상수를 입력값으로 사용하여 그 관계를 조사하였으며, 스프링 상수가 커질수록 줄눈의 하중전달효율이 증가하는 것으로 나타났다. 슬래브와 기증의 다양한 탄성계수와 두께를 사용하여 슬래브의 거동과 하중전달효율에 미치는 재료물성과 기하학적 형상의 영향을 분석하였다. 그 결과 노상의 탄성계수는 기층의 탄성계수와 슬래브 및 기층의 두께보다 더 큰 영향을 미치는 것으로 나타났다. 또한 양 또는 영의 온도구배에서보다는 음의 온도구배에서 슬래브의 거동과 하중 전단효율이 더 민감 하게 변화하였으며, 낮은 강성의 줄눈은 슬래브의 온도구배에 더 민감한 것으로 나타났다.

EVALUATION OF SLAG MIXTURE PROPERTIES USING GYRATORY COMPACTOR

Lee, Kwan-Ho Korean Society of Road Engineers 1999 한국도로포장공학회 논문집 Vol.1 No.2

Compaction of asphalt pavement is one of the important processes to make good quality one. There are many laboratory-compaction methods to simulate field compaction, including Marshall compaction, Hveem compaction, gyratory compaction, and etc. The most common method used to determine the fundamental properties of asphalt mixture for design is Marshall method which is using impact energy. However, there is major difference between field compaction using kneading compaction and Marshall compaction using impact energy. Therefore, the gyratory compactor, which currently is the best to simulate the field compaction, was employed. The fundamental properties of asphalt specimen compacted by gyratory compactor and Marshall compactor were determined using laboratory test. From the tests, slag mixture with carbon black or pyrolyzed carbon black showed better performances, such as, in low susceptibility to temperature, high resistance against water and rutting, and high resilient modulus and indirect tensile strength.

Evelopment of a Practical Mechanistic-Empirical design Procedure for Flexible Pavements

박동엽,김형배,서영찬,Park, Dong-Yeob,Kim, Hyung-Bae,Buch, Neeraj,Suh, Young-Chan Korean Society of Road Engineers 2002 한국도로포장공학회 논문집 Vol.4 No.3

Design methods for new flexible pavements and overlays are in the transition from empirical to mechanistic approach, and many state highway agencies trend to move toward the adoption and use of mechanistic-empirical (M-E) design in new constructions and rehabilitations of flexible pavements. Hence, the Michigan Department of Transportation (MDOT) decided to develop a M-E flexible pavement design procedure, in which major pavement distresses such as fatigue cracking and rutting are employed as indicators of the serviceability of a flexible pavement. The main concept of the developed design procedure is that a designed pavement that is supposed to carry a certain number of traffic must satisfy designated thresholds of rut depths and fatigue lives during a service period. For the M-E design procedure, transfer functions were developed to predict rut-depths and fatigue lives. These functions related the pavement responses to pavement performance. For validation, three current new flexible pavement design cases were obtained from the MDOT. In these cases, asphalt concrete (AC) layer thicknesses determined by the suggested M-E procedure compare favorably with those determined by the current MDOT design practice that is based on AASHTO design guide. This finding implies that the suggested Michigan M-E flexible pavement design procedure can provide a good opportunity to improve the current design practice.

Application of Load and Resistance Factor Design Format to Designing Flexible Pavements

김형배,Kim, Hyung-Bae Korean Society of Road Engineers 2003 한국도로포장공학회 논문집 Vol.5 No.1

The objective of pavement design, just as with the design of other structures, is to obtain the most economical designs at specified levels of reliability. Methods that yield designs with different levels of reliability are undesirable, and over the course of time design approaches in the U.S. and Europe have converged toward the Load and Resistance Factor Design (LRFD) format in order to assure uniform reliability. At present the LRFD format has been implemented in concrete, steel, wood and bridge design specifications. In this paper, reliability theories are used to illustrate the development of an LRFD format for Mechanistic-Empirical (M-E) design of flexible pavements as an alternative of its reliability module. It is shown in this paper that ten candidate pavement sections designed with a reliability level using the AASHTO design guide (1986) do not have uniform structural reliability in terms of pavement mechanistic distress such as fatigue cracking and the uniform reliability can be achieved by using the LRFD format.

Theoretical Development of Compaction Density

허정도,김한용,남영국,Huh, Jung-Do,Kim, Han-Yong,Nam, Young-Kug Korean Society of Road Engineers 2000 한국도로포장공학회 논문집 Vol.2 No.1

Compaction is known to critically affect pavement performance. Due to its importance, a theoretical modelling of compacted density in the term of number of roller coverages is attempted by assuming compaction process essentially identical to pavement rutting. Excellent data fittings by the developed equation may prove the validation of assumptions made as well as justification of its use. According to the derived equation, a plot of density difference with respect to number of roller coverages in the logarithmic scale Produces a linear relationship. However, this linearity is turned out to be deviated by cooling effect, change of amplitude and frequency. Investigation of these three factors proposes a new generalized compaction density equation, which shows a promising future. By applying this general formula, the equations for the number of roller coverages required and the final compaction density obtained for a particular compaction project is derived first time in compaction research.

Development of a Combined Model for Soil Damping Behavior

배윤신,Bae, Yoon-Shin Korean Society of Road Engineers 2008 한국도로학회논문집 Vol.10 No.2

Damping behavior of various soil models are compared to actual observed soil damping behavior. Several nonlinear soil models were used and evaluated to predict damping behavior of soils. A combined damping model incorporating both nonvisous and hysteretic damping behavior was developed to better approximate soil behavior. The strengths and limitations of this model are discussed. 다양한 지반의 모델들을 이용한 감쇠 거동을 식제 지반의 감쇠 거동과 비교하였다. 지반의 감쇠 거동을 예측하기 위해 몇 가지 비선형 지반 모델들을 이용하고 평가하였다. 지반 거동을 대략적으로 잘 묘사하기 위해 비점성 감쇠 및 이력감쇠 거동은 모두 고려하는 복합 감쇠 모델이 개발 되었다. 이 모델의 장점 및 문제점이 논의 되었다.