Application of Viscoelastic Continuum Damage Model Based Finite Element Analysis to Predict the Fatigue Performance of Asphalt Pavements

Y. Richard Kim,Cheolmin Baek,B. Shane Underwood,Vijay Subramanian,Murthy N. Guddati,Kwangho Lee 대한토목학회 2008 KSCE JOURNAL OF CIVIL ENGINEERING Vol.12 No.2

The Viscoelastic Continuum Damage (VECD) model has been implemented into a finite element package (FEP+) to predict thefatigue performance of asphalt concrete (AC) mixtures tested at the Federal Highway Administration Accelerated Load Facility(FHWA ALF) and the Korea Expressway Corporation (KEC) test road project sites. Both the VECD model and the FEP++ weredeveloped at North Carolina State University. The conceptual appr s of thepavement system that are related to the material from those related to the boundary conditions. It is believed that this study is the firstapplication of an integrated structural/material mechanistic model for the fatigue performance prediction of AC pavements wheredamage in the asphalt layers is considered for the full time history and where the change in stiffness due to damage evolution iscaptured in the subsequent calculation of damage. The VECD model accounts for the viscoelastic nature of AC mixtures withgrowing damage, whereas the finite element model accounts for other important characteristics, such as temperature, layer thickness,stiffness gradient, etc. The controlled FHWA ALF experiment allows a direct comparison between observed and modeled fatigueperformance. Because the KEC test road experiment is subjected nd environmental factors, the finiteelement simulation results are used to examine the effects of specific parameters in the pavement system on fatigue performance. Inthis regard, the model is found to effectively capture the effects of changes in layer thickness, layer material, and layer type. The needto develop transfer functions for true field performance prediction is also shown, and a simple example function is developed as proofof this concept.

캘리포니아주의 피해자의 권리와 피해보상

Richard Y. Kim 가천대학교 법학연구소 2011 가천법학 Vol.4 No.3

몇 십년 전만해도, 피해자가 통지를 받고, 출석하여, 진술할 수 있는 법적 권리는 거의 형사사법 체계내에서 없었다. 피해자는 재판 절차 또는 피고인의 체포나 석방에 대해 고지될 필요가 없었으므로, 그들은 재판이나 다른 절차에 출석할 권리가 없었고, 형의 선고나 기타 심리를 위해 법정에서 진술할 권리도 없었다. 더욱이, 피해자 지원 프로그램은 사실상 없는 것이나 마찬가지였다. 그 이후로, 범죄피해자의 법적인 권리를 창설하고 지원하는 프로그램에서 놀라운 진전이 있었다. 오늘날, 캘리포니아와 대부분의 다른 주는 실정법 내에 범죄피해자의 기본적인 권리와 보호를 위한 광범위한 규정체계를 가지고 있다. 피해자 권리규정은 연방, 주, 지방 형사사법제도 차원에서 피해자를 대하는 태도에 중대한 영향을 미쳤다. A few decades ago, victims had few legal rights to be informed, present and heard within the criminal justice system. Victims did not have to be notified of court proceedings or of the arrest or release of the defendant, they had no right to attend the trial or other proceedings, and they had no right to make a statement to the court at sentencing or at other hearings. Moreover, victim assistance programs were virtually non-existent. Since then, there have been tremendous strides in the creation of legal rights and assistance programs for victims of crime. Today, in California and most other states havean extensive body of basic rights and protections for victims of crime within its statutory code. Victims' rights statutes have significantly influenced the manner in which victims are treated within the federal, state, and local criminal justice systems.

장출혈성 대장균 혈청군 O157, O26, O25, O55, O103, O104, O111 및 O145 가토면역 항혈청의 응집소 특이성에 관한 연구

김호훈(Ho Hoon Kim ),강연호(Y.H. Kang ),김성한(S.H. Kim ),박미선(M.S. Park ),유재연(J.Y. Yu),전정훈(J.H. Chun ),Richard A. Wilson,이복권(B.K. Lee) 大韓微生物學會 1998 大韓微生物學會誌 Vol.33 No.5

The Nondestructive Test in Fatigue Damages of Asphalt Concrete Pavements Using Accelerated Loading Facility

Yongon Kim,Y. Richard Kim 대한토목학회 1998 KSCE journal of civil engineering Vol.2 No.3

손상이 증가하는 아스팔트 콘크리트의 점탄성 구성모델

이현종,Y. Richard Kim,김선훈 한국전산구조공학회 1997 한국전산구조공학회논문집 Vol.10 No.4

본 논문에서는 반복하중에 의해 손상을 입은 아스팔트 콘크리트의 점탄성 구성모델에 대한 역학적 접근방법을 제시하였다. 모의변수로 나타낸 탄성-점탄성 일치원리는 아스팔트 콘크리트의 점탄성과 시간의존 손상의 증가를 별도로 평가하도록 적용되었다. 선형-점탄성 파괴역학에 사용되고 있는 미소균열의 증가법칙이 물체내 손상증가를 나타내는데 성공적으로 사용되었다. 응력과 모의변형도로 나타나는 구성방정식은 먼저 변형도조절에 대해 세워졌으며, 응력과 모의변형도를 모의응력과 변형도로 간단하게 대체함으로써 응력조절 구성방정식으로 변형되었다. 모의응력으로 나타낸 변형된 구성방정식은 응력조절모드에서 파괴에 이르는 아스팔트 콘크리트의 모든 역학적 거동을 충분히 예측하고 있다. Mechanical behavior of asphalt concrete that accounts for viscoelasticity and damage evolution under cyclic loading conditions is modeled and presented in this paper. An elastic-viscoelastic correspondence principle in terms of pseudo variables is applied to separately evaluate viscoelasticity and time-dependent damage growth in asphalt concrete. A microcrack growth law, which is commonly employed in linear viscoelastic fracture mechanics, is successfully used for describing the damage growth in the body. A constitutive equation in terms of stress and pseudo strain is first established for controlled-strain mode, and then transformed to controlled-stress constitutive equation by simply replacing stress and pseudo strain with pseudo stress and strain. The transformed constitutive equation in terms of pseudo stress satisfactorily predicts the mechanical behavior of asphalt concrete all the way up to failure under controlled-stress modes.

Layer Moduli Prediction of Aspalt Concrete Pavements Using Artificial Neural Network

Yongun Kim,Y. Richard Kim 대한토목학회 1998 KSCE journal of civil engineering Vol.2 No.4

Viscoelastoplastic Modeling of the Behavior of Hot Mix Asphalt in Compression

윤태영,Y. Richard Kim 대한토목학회 2013 KSCE Journal of Civil Engineering Vol.17 No.6

The uniaxial stress-strain behavior of Hot Mix Asphalt (HMA) in compression is studied using the Viscoelastoplastic Continuum Damage (VEPCD) modeling approach. The VEPCD model addresses the viscoelasticity, microcracking damage, and viscoplastic flow of the asphalt binder. Its strength has been proven in tension testing where the stress-strain behavior of various HMAs subjected to a random loading history is accurately predicted from a set of simple tests. The application of the VEPCD model to the compressive behavior of HMA reveals that an additional mechanism, aggregate interlocking, must be addressed to ensure the accurate modeling of HMA behavior. The corrective measure that is implemented in this paper to account for the effect of aggregate interlocking is still preliminary, but the approach shows promise for developing a sound, mechanistic model for the HMA behavior in compression and, therefore, rutting performance.

Evaluation of polymer-modified chip seals at low temperatures

Lee, Jaejun,Kim, Richard Y. Taylor Francis 2014 The international journal of pavement engineering Vol.15 No.3

Adsorption of Benzene from Aqueous Solution Using Base Modified Expanded Perlite

Appiah-Ntiamoah, Richard,Mai, Xuan Thang,Momade, Francis W.Y.,Kim, Hern Trans Tech Publications, Ltd. 2012 Advanced materials research Vol.622 No.-

<P>In this study, the adsorption capacity of expanded perlite (EP) for benzene at low concentrations in water was investigated after EP was treated with sodium hydroxide (NaOH). IR spectra used to characterize the modified EP showed that there was no bonding between NaOH and the hydroxyl groups on the surface of EP. However, the NaOH provided a basic medium for negatively charged surface oxide ions (-SO-) to form on EP. This fact was corroborated by pH readings of the modification solution. This reduced in pH from 10 to 9 at the end of the reaction which indicated that the hydroxyl OH- groups on the EP underwent deprotonation and hence releases H+ into the solution, and also positive sites on EP adsorbed OH- ions from the base solution. Mahir et al. in their paper Zeta potential of unexpanded and expanded perlite samples in various electrolyte media confirmed that EP has no isoelectric point and exhibits negative zeta potential in the pH range of 2-11. The surface oxides (-SO-) were believed to have given EP it adsorptive potential. Adsorption isotherm values correlated reasonably well with the Langmuir isotherm model and it parameters (qo and K) were obtained using linear regression analysis. A maximum adsorption capacity (qo) value of 19.42 mg/g was achieved.</P>

Development of the Nondestructive Methods to Detect Voids under Concrete Slabs Using Wave Analysis

김용곤,김영수,Kim, Yongon,Kim, Y. Richard 한국구조물진단유지관리공학회 1998 한국구조물진단유지관리공학회 논문집 Vol.2 No.1

많은 주거용 및 상업용 건물에서 콘크리트 구조물이 사용되고 있는데 콘크리트 슬래브 아래의 기초부분에 공동이 생기는 경우가 종종 발견되었다. 이 현상은 진동하중, 반복되는 충격, 흙의 유실, 혹은 불량시공 등 여러가지 이유에 의해 발생할 수 있다. 이러한 현상은 구조물의 지지력을 저하시키고 결국 수명을 단축시키는 원인이 되므로 이러한 문제는 일찍 발견되고 조치가 취해질수록 구조물의 수명을 연장시킬 수 있을 것이다. 이러한 공동이 슬래브 아래에서 형성되고 커져가는 과정을 모니터할 수 있으면 현재 상태에서 지지력을 결정하고 또한 앞으로 남은 수명을 예측함으로써 적절한 유지보수계획을 세우는 데에 큰 도움이 될 것이다. 이 연구에서는 음파와 응력파, 특히 표면파가 슬래브 아래의 공동을 찾아내는데 이용되었고 두 가지 방법의 효과가 상호 비교되었다. 두개의 콘크리트 슬래브를 만들어 이용했는데 하나는 미리 공동이 만들어져 있었고 다른 하나에는 공동이 없었다. 공동이 없던 슬래브는 처음 손상안된 상태에서 실험을 한 후 나중에 하부에 공동을 만들어 다시 실험하였다. 실험결과와 실제 공동의 위치가 잘 일치되는 것으로 나타났다. 응력파를 이용하는 방법과 음파를 이용하는 방법사이의 장단점이 비교검토되었고 실험의 표준방법과 결과에 대한 일반적인 기준이 확립되어야 하는 필요성에 대해서도 설명되었다.