Statics corrections for shallow seismic refraction data

Palmer Derecke,Nikrouz Ramin,Spyrou Andreur Korean Society of Earth and Exploration Geophysici 2005 지구물리와 물리탐사 Vol.8 No.1

The determination of seismic velocities in refractors for near-surface seismic refraction investigations is an ill-posed problem. Small variations in the computed time parameters can result in quite large lateral variations in the derived velocities, which are often artefacts of the inversion algorithms. Such artefacts are usually not recognized or corrected with forward modelling. Therefore, if detailed refractor models are sought with model based inversion, then detailed starting models are required. The usual source of artefacts in seismic velocities is irregular refractors. Under most circumstances, the variable migration of the generalized reciprocal method (GRM) is able to accommodate irregular interfaces and generate detailed starting models of the refractor. However, where the very-near-surface environment of the Earth is also irregular, the efficacy of the GRM is reduced, and weathering corrections can be necessary. Standard methods for correcting for surface irregularities are usually not practical where the very-near-surface irregularities are of limited lateral extent. In such circumstances, the GRM smoothing statics method (SSM) is a simple and robust approach, which can facilitate more-accurate estimates of refractor velocities. The GRM SSM generates a smoothing 'statics' correction by subtracting an average of the time-depths computed with a range of XY values from the time-depths computed with a zero XY value (where the XY value is the separation between the receivers used to compute the time-depth). The time-depths to the deeper target refractors do not vary greatly with varying XY values, and therefore an average is much the same as the optimum value. However, the time-depths for the very-near-surface irregularities migrate laterally with increasing XY values and they are substantially reduced with the averaging process. As a result, the time-depth profile averaged over a range of XY values is effectively corrected for the near-surface irregularities. In addition, the time-depths computed with a Bero XY value are the sum of both the near-surface effects and the time-depths to the target refractor. Therefore, their subtraction generates an approximate 'statics' correction, which in turn, is subtracted from the traveltimes The GRM SSM is essentially a smoothing procedure, rather than a deterministic weathering correction approach, and it is most effective with near-surface irregularities of quite limited lateral extent. Model and case studies demonstrate that the GRM SSM substantially improves the reliability in determining detailed seismic velocities in irregular refractors.

Drug Selection in Treatment of Polyarthritis

Palmer, David G. Medical Publications Korea 1974 Medical Progress Vol.1 No.6

The Role of Children in Daesoon Jinrihoe, a Korean New Religion

PALMER, Susan J.,GREENBERGER, Jason DAOS(The Daesoon Academy of Sciences) 2021 Journal of Daesoon Thought and the Religions of Ea Vol.1 No.1

This study attempts to investigate the role of children in the Korean new religious movement, Daesoon Jinrihoe. The research method combined archival studies with qualitative research; interviews with two members involved in educating youth through the establishment of Youth Camps and Donggeurami, the order's youth magazine. Our four research questions were: 1. Do children play a central role in the millennial vision of this NRM? 2. Are children separated from the world? 3. Have Daesoon childrearing methods been challenged by secular authorities or anticult groups? 4. Are there procedures to educate children in the religious beliefs and values of their parents and the community? Our results found that Daesoon Jinrihoe appears to be a religion designed for adults. Children do not usually participate in religious activities. On the other hand, since 2005 there has been a strategic effort to educate the children in the faith of their parents, through the establishment of Youth Camps and the youth magazine, Donggeurami.

Mefloquine : For Prophylaxis and Treatment of Malaria

Palmer, Katherine J.,Holiday,Stephen M.,Brogden,Rex N. Medical Publications Korea 1993 Medical Progress Vol.15 No.10

The Status of Studies on the Korean Independence Movement in the U.S.

Palmer, Brandon 한국근현대사학회 2023 한국 근현대사 연구 Vol.105 No.-

The Republic of Korea has been among the United States’ most reliable allies over the past seventy years. The two countries have developed a security alliance and an economic relationship that is mutually beneficial; for example, the United States has armed forces stationed on the Korean Peninsula, and South Korea is America’s sixth largest trade partner. However, despite the closeness of the two nations, American society has remained Eurocentric. As a result, most Americans know little about South Korea, its history, or its struggles against Japanese colonialism, which are critical to Korean nationalism. This essay is an assessment of what Americans know about the Korean independence movement and how to rectify American ignorance of the Korean struggle for freedom.

Options available on University English Reading Instruction in Korea

Palmer, Robert 동의대학교 2004 인간과 문화 연구 Vol.- No.9

An Alternative Approach to the Language Major

Palmer, Benjamin W. 충남대학교 어학연구소 1981 언어 Vol.2 No.-

Much of what we read and hear today about the study of foreign languages has to do with how to learn a language, how to teach a language and how people have achieved various degrees of success in studying and learning laguages. There are also available many testimonials devoted to the varied experiences of people mostly young-who have discovered new horizons through contact with another language. What we do not read much about is why people study foreign languages or what they expect to gain from their work.

Maximising the lateral resolution of near-surface seismic refraction methods

Palmer, Derecke Korean Society of Earth and Exploration Geophysici 2009 지구물리와 물리탐사 Vol.12 No.1

The tau-p inversion algorithm is widely employed to generate starting models with most computer programs, which implement refraction tomography. This algorithm emphasises the vertical resolution of many layers, and as a result, it frequently fails to detect even large lateral variations in seismic velocities, such as the decreases which are indicative of shear zones. This study demonstrates the failure of the tau-p inversion algorithm to detect or define a major shear zone which is 50m or 10 stations wide. Furthermore, the majority of refraction tomography programs parameterise the seismic velocities within each layer with vertical velocity gradients. By contrast, the Generalized Reciprocal Method (GRM) inversion algorithms emphasise the lateral resolution of individual layers. This study demonstrates the successful detection and definition of the 50m wide shear zone with the GRM inversion algorithms. The existence of the shear zone is confirmed by a 2D analysis of the head wave amplitudes and by numerous closely spaced orthogonal seismic profiles carried out as part of a later 3D refraction investigation. Furthermore, an analysis of the shot record amplitudes indicates that a reversal in the seismic velocities, rather than vertical velocity gradients, occurs in the weathered layers. The major conclusion reached in this study is that while all seismic refraction operations should aim to provide as accurate depth estimates as is practical, those which emphasise the lateral resolution of individual layers generate more useful results for geotechnical and environmental applications. The advantages of the improved lateral resolution are obtained with 2D traverses in which the structural features can be recognised from the magnitudes of the variations in the seismic velocities. Furthermore, the spatial patterns obtained with 3D investigations facilitate the recognition of structural features such as faults which do not display any intrinsic variation or 'signature' in seismic velocities.

The Effects of Schemata Activation and L2 Glossing on Reading Comprehension

Palmer, Robert 팬코리아영어교육학회 2004 영어교육연구 Vol.16 No.2

There is a lot of faith in the idea of providing rhetorical structure and/or background and content information as a pre-reading activity. On the other hand, the available research indicates that providing L2 glosses (written explanations of words and phrases in the text) is usually of no benefit. This paper reexamines the issue of L2 glossing in a way that has never been done before; that is, through extensive glossing. In this study, humanities freshmen (n=138) were divided into three groups: an instruction group that received 10 minutes of pre-reading instruction concerning the rhetorical structure, background and contents of the passage; an L2 gloss group with abundant L2 glosses; and a control. The ANCOVA revealed that the L2 gloss group significantly outperformed the other groups, and contrary to other studies, the instruction group did not outperform the control group despite the fact that the instruction group spent 25 minutes on task compared with 20 minutes on task for the other groups. The reasons for this are examined and the implications are presented.

When the Future Disappears: The Modernist Imagination in Late Colonial Korea

Palmer, Brandon 성균관대학교 동아시아학술원 2015 Sungkyun Journal of East Asian Studies Vol.15 No.1