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( William A. Pettigrew ) 고려대학교 역사연구소(구 역사학연구회) 2012 사총 Vol.77 No.-
본 논문은 고대 시기부터 오늘날까지 유럽 정체성 형성과 노예제의 관계를 살펴본다. 노예제는 아메리카 정체성의 형성만큼이나 유럽 정체성에 커다란 영향을 끼쳤다. 이 둘의 관계는 세 가지 시기로 구분할 수 있는데 우선 기독교와 중세의 자유 개념으로부터 파생된 유럽 정체성은 유럽인들이 다른 유럽인들을 노예로 삼는 것에 대한 문화적 걸림돌이 되었다. 둘째, 유럽의 근대 자유주의의 정치적 이상은 아메리카 대륙에서 아프리카 노예제의 형성과 폐지에 있어서 중요한 역할을 맡았다. 마지막으로 유럽 세계주의는 노예제 철폐에 있어서 유럽 전체의 계몽운동이 달성한 집합적인 성과보다도 더 크게 기여했다. 나아가 본 논문은 유럽 정체성 형성의 핵심적인 결정요소로서 노예제의 정체성 만들기 작업이 오늘날 유럽 정체성 변화를 가져올 수 있는 방식들을 논한다.
Bioremediation Options for Nuclear Sites a Review of an Emerging Technology
Callum Robinson,Matthew White-Pettigrew,Samuel Shaw,Katherine Morris,James Graham,Jonathan R. Lloyd 한국방사성폐기물학회 2022 방사성폐기물학회지 Vol.20 No.3
60+ Years of nuclear power generation has led to a significant legacy of radioactively contaminated land at a number of nuclear licenced “mega sites” around the world. The safe management and remediation of these sites is key to ensuring there environmental stewardship in the long term. Bioremediation utilizes a variety of microbially mediated processes such as, enzymatically driven metal reduction or biominerialisation, to sequester radioactive contaminants from the subsurface limiting their migration through the geosphere. Additionally, some of these process can provide environmentally stable sinks for radioactive contaminants, through formation of highly insoluble mineral phases such as calcium phosphates and carbonates, which can incorporate a range of radionuclides into their structure. Bioremediation options have been considered and deployed in preference to conventional remediation techniques at a number of nuclear “mega” sites. Here, we review the applications of bioremediation technologies at three key nuclear licenced sites; Rifle and Hanford, USA and Sellafield, UK, in the remediation of radioactively contaminated land.
A New Method for Estimating High-Frequency Radar Error Using Data from Central San Francisco Bay
Maxwell Hubbard,Donald Barrick,Newell Garfield,Jim Pettigrew,Carter Ohlmann,Matthew Gough 한국해양과학기술원 2013 Ocean science journal Vol.48 No.1
This study offers a new method for estimating High- Frequency (HF) radar surface current velocity error in data comparisons with other types of instrumentation. A new method is needed in order to remove the zero-mean random spatial and temporal fluctuations present in surface-current measurements from all sensors. Conventional methods for calculating radar error when comparing with another instrument have included their root mean square differences and scatter plots that provide correlation coefficient and slope/intercept of the regression line. It seems that a meaningful estimate of radar error should attempt to remove both sensors' zero mean random fluctuations, inasmuch as possible. We offer and compare a method that does this. The method was tested on data collected in the Central San Francisco Bay, where GPS surface-drifter deployments were conducted within the coverage of four 42 MHz radars over six days in October of 2008. Drifters were continuously deployed in these areas over the sampling days, providing 525 usable drifter measurements. Drifter and radar measurements were averaged into thirty-minute time bins. The three-day long-term averages from the sampling areas were then subtracted from the thirtyminute averages to remove biases associated with comparisons done with short, disjoint time-sample periods. These were then used to develop methods that give radar error or bias after the random fluctuations have been removed. Results for error estimates in this study are commensurate with others where random fluctuations have been filtered, suggesting they are valid. The estimated error for the radars in the SF Bay is low, ranging from -7.57 cm/s to 0.59 cm/s.
Parametric study of two-phase flow by integral analysis based on power law distribution
심우건,N. W. Mureithi,M. J. Pettigrew 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.7
To understand the fluid dynamic forces acting on a structure subjected to two-phase flow, it is essential to obtain detail information on the characteristics of that flow. The distributions of flow parameters across a pipe, such as gas velocity, liquid velocity and void fraction,may be assumed to follow a power law (Cheng 1998; Serizawa et al. 1975). The void fraction profile is, for example, uniform for bubbly flow, whereas for slug flow it is more or less parabolic. In the present work, the average values of momentum flux, slip ratio and other parameters were derived by integral analysis, based on approximate power law distributions. A parametric study with various distributions was performed. The existing empirical formulations for average void fraction, proposed by Wallis (1969), Zuber et al. (1967) and Ishii (1976), were considered in the derivation of the present results. Notably, the unsteady momentum flux for slug flow was approximated.
Kang, H.S.,Mureithi, N.W.,Pettigrew, M.J. Academic Press 2012 Journal of fluids and structures Vol.35 No.-
An analytical model of annular-flow-induced vibration of a pinned-pinned cylinder is proposed. The model is based on three main assumptions: (i) small perturbations in flow components, (ii) negligible radial flow to reduce the annular flow to two-dimensional flow, and axial flow only for reduction to a one-dimensional flow, and (iii) perturbation frictional loss depending on the variation of axial perturbation velocity in terms of space and time. In this study, it is concluded that (a) the difference in fluidelastic forces between two- and one-dimensional flow models mostly depends on cylinder radius, and on whether perturbation flow is mainly allowed in the axial or circumferential direction, (b) the one-dimensional flow model should be limited to 1-d.o.f. vibration analysis or the case of a cylinder having a large radius-to-length ratio, and (c) the perturbation assumption has little effect on the dynamics of annular-flow-induced vibrations; however, the critical flow velocity is diminished considerably. Finally, preliminary results suggest that fluid friction may significantly modify the predicted model dynamics.