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RISS 인기검색어
- 검색키워드
- 저자 : Block, Kai Tobias (검색결과 24 건)
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Block, Kai Tobias,Chandarana, Hersh,Milla, Sarah,Bruno, Mary,Mulholland, Tom,Fatterpekar, Girish,Hagiwara, Mari,Grimm, Robert,Geppert, Christian,Kiefer, Berthold,Sodickson, Daniel K. Korean Society of Magnetic Resonance in Medicine 2014 Investigative Magnetic Resonance Imaging Vol.18 No.2
Purpose : To describe how a robust implementation of a radial 3D gradient-echo sequence with stack-of-stars sampling can be achieved, to review the imaging properties of radial acquisitions, and to share the experience from more than 5000 clinical patient scans. Materials and Methods: A radial stack-of-stars sequence was implemented and installed on 9 clinical MR systems operating at 1.5 and 3 Tesla. Protocols were designed for various applications in which motion artifacts frequently pose a problem with conventional Cartesian techniques. Radial scans were added to routine examinations without selection of specific patient cohorts. Results: Radial acquisitions show significantly lower sensitivity to motion and allow examinations during free breathing. Elimination of breath-holding reduces failure rates for non-compliant patients and enables imaging at higher resolution. Residual artifacts appear as streaks, which are easy to identify and rarely obscure diagnostic information. The improved robustness comes at the expense of longer scan durations, the requirement for fat suppression, and the nonexistence of a time-to-center value. Care needs to be taken during the configuration of receive coils. Conclusion: Routine clinical use of radial stack-of-stars sequences is feasible with current MR systems and may serve as substitute for conventional fat-suppressed T1-weighted protocols in applications where motion is likely to degrade the image quality.
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Neutron transmission and capture measurements and analysis of Dy from 0.01 to 550 eV
Block, R.C.,Bishop, M.C.,Barry, D.P.,Leinweber, G.,Ballad, R.V.,Burke, J.A.,Rapp, M.J.,Danon, Y.,Youmans, A.,Drindak, N.J.,Kim, G.N.,Kang, Y.-R.,Lee, M.W.,Landsberger, S. Elsevier 2017 Progress in nuclear energy Vol.94 No.-
<P><B>Abstract</B></P> <P>Neutron capture and transmission measurements were carried out from 0.01 to over 600 eV on both natural Dy and samples highly enriched in <SUP>164</SUP>Dy. These data were analyzed for resonance parameters utilizing the SAMMY Bayesian analysis code to simultaneously fit both the capture and transmission data. Parameters were obtained for 17 resonances in Dy isotopes up to 18 eV and for the <SUP>164</SUP>Dy resonances near 147, 450 and 540 eV. The thermal capture cross section (at 0.0253 eV) and capture resonance integral were determined for <SUP>164</SUP>Dy.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Transmission and capture measurements from thermal to 550 eV on Dy and <SUP>164</SUP>Dy samples. </LI> <LI> Bayesian analysis provided resonance parameters from the combined measurements. </LI> <LI> Liquid samples were used to obtain uniformly thin <SUP>164</SUP>Dy samples. </LI> <LI> The <SUP>164</SUP>Dy thermal cross section and resonance integral were obtained from these measurements. </LI> <LI> Improvements were made for the 5.45 eV <SUP>162</SUP>Dy resonance parameters. </LI> </UL> </P>
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( Celiac Plexus Block ),( Yu Gyeong Kong ),( Jin Woo Shin ),( Jeong Gill Leem ),( Jeong Hun Suh ) 대한통증학회 2013 The Korean Journal of Pain Vol.26 No.4
Conventional transcrural CPB via the “walking off” the vertebra technique may injure vital organs while attempting to proximally spread injectate around the celiac plexus. Therefore, we attempted the CT simulated fluoroscopy-guided transdiscal approach to carry out transcrural CPB in a safer manner, spreading the injectate more completely and closely within the celiac plexus area. A 54-year-old male patient with pancreatic cancer suffered from severe epigastric pain. The conventional transcrural approach was simulated, but the needle pathway was impeded by the kidney on the right side and by the aorta on the left side. After simulating the transdiscal pathway through the T11-12 intervertebral disc, we predetermined the optimal insertion point (3.6 cm from the midline), insertion angle (18 degrees), and advancement plane, as well as the proper depth. With the transdiscal approach, we successfully performed transcrural CPB within a narrow angle, and the bilateral approach was not necessary as we were able to achieve the bilateral spread of the injectate with the single approach. (Korean J Pain 2013; 26: 396-400)
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The Definition of Fire Resistance Requirements for Stadium and Arena Developments Based on Risk
Florian M. Block,Neal A. Butterworth 한국강구조학회 2009 International Journal of Steel Structures Vol.9 No.1
In the United Kingdom, as in most other countries, the required fire resistance period of a building is traditionally given by the recommendations of prescriptive documents, such as the Approved Document B, depending on the usage and the height of the building. However, for large developments like stadia and arenas, which involve different usages such as assembly, office and retail facilities in combination with a very large number of people and the significance of this type of structure to the communities, these simple rules given in the prescriptive guidance to fire safety are not applicable. Furthermore, structural fire protection forms a significant part of the cost of a structure and also plays a significant part in the environmental impact and the embodied energy. Therefore, a risk based approach to the fire resistance requirements of large stadia and arenas has been developed and validated in this paper to ensure that the appropriate standard of safety is achieved in the most appropriate and economic manner. The approach allows a detailed assessment of the risk of failure of individual elements of structure and structural systems in a stadium rather than specifying a single fire resistance period for the whole building, which might be overly conservative for some members, but potentially unsafe for critical elements. The approach also allows for investigating the influence of individual parameters such as management, and the fire load. The method ensures that all three risk parameters i.e. frequency, probability, consequence will be assessed for the different structural elements based on available data from similar buildings, calculations and experiences. It could be shown that the proposed method gives consistent and comparable results for office, retail and assembly buildings, if compared with the recommendations given in the British Standard BS9999. It should be noted that the approach is based on the principles of risk; however it is semi-quantitative, and as a result contains some subjectivity. Therefore, it is important that the results are assessed for consistency and that they are logical and explainable. In the United Kingdom, as in most other countries, the required fire resistance period of a building is traditionally given by the recommendations of prescriptive documents, such as the Approved Document B, depending on the usage and the height of the building. However, for large developments like stadia and arenas, which involve different usages such as assembly, office and retail facilities in combination with a very large number of people and the significance of this type of structure to the communities, these simple rules given in the prescriptive guidance to fire safety are not applicable. Furthermore, structural fire protection forms a significant part of the cost of a structure and also plays a significant part in the environmental impact and the embodied energy. Therefore, a risk based approach to the fire resistance requirements of large stadia and arenas has been developed and validated in this paper to ensure that the appropriate standard of safety is achieved in the most appropriate and economic manner. The approach allows a detailed assessment of the risk of failure of individual elements of structure and structural systems in a stadium rather than specifying a single fire resistance period for the whole building, which might be overly conservative for some members, but potentially unsafe for critical elements. The approach also allows for investigating the influence of individual parameters such as management, and the fire load. The method ensures that all three risk parameters i.e. frequency, probability, consequence will be assessed for the different structural elements based on available data from similar buildings, calculations and experiences. It could be shown that the proposed method gives consistent and comparable results for office, retail and assembly buildings, if compared with the recommendations given in the British Standard BS9999. It should be noted that the approach is based on the principles of risk; however it is semi-quantitative, and as a result contains some subjectivity. Therefore, it is important that the results are assessed for consistency and that they are logical and explainable.
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kai tobias block,Hersh Chandarana1,Sarah Milla,Mary Bruno,Tom Mulholland,Girish Fatterpekar,Mari Hagiwara,Robert Grimm,Christian Geppert,Berthold Kiefer 대한자기공명의과학회 2014 Investigative Magnetic Resonance Imaging Vol.18 No.2
Purpose : To describe how a robust implementation of a radial 3D gradient-echo sequence with stack-of-stars samplingcan be achieved, to review the imaging properties of radial acquisitions, and to share the experience from more than5000 clinical patient scans. Materials and Methods: A radial stack-of-stars sequence was implemented and installed on 9 clinical MR systems operatingat 1.5 and 3 Tesla. Protocols were designed for various applications in which motion artifacts frequently pose a problemwith conventional Cartesian techniques. Radial scans were added to routine examinations without selection of specificpatient cohorts. Results: Radial acquisitions show significantly lower sensitivity to motion and allow examinations during free breathing. Elimination of breath-holding reduces failure rates for non-compliant patients and enables imaging at higher resolution. Residual artifacts appear as streaks, which are easy to identify and rarely obscure diagnostic information. The improvedrobustness comes at the expense of longer scan durations, the requirement for fat suppression, and the nonexistence of atime-to-center value. Care needs to be taken during the configuration of receive coils. Conclusion: Routine clinical use of radial stack-of-stars sequences is feasible with current MR systems and may serve assubstitute for conventional fat-suppressed T1-weighted protocols in applications where motion is likely to degrade theimage quality
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Fission Physics and Cross Section Measurements with a Lead Slowing down Spectrometer
Y. Danon,R. Block,J. Thompson,C. Romanoy 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
A Lead Slowing Down Spectrometer (LSDS) provides a high neutron flux environment that enables measurements of small samples (∼μg) or samples with small cross sections (tens of μb). The LSDS at Rensselaer Polytechnic Institute (RPI) was previously used for fission cross section measurements and for studies of methods for assay of used nuclear fuel. The effective energy range for the LSDS is 0.1 eV to 10 keV with energy resolution of about 35%. Two new LSDS applications were recently developed at RPI; the first enables simultaneous measurements of the fission cross section and fission fragment mass and energy distributions as a function of the incident neutron energy. The second enables measurements of the (n,α) and (n,p) cross sections for materials with a positive Q value for these reactions. Fission measurements of ^(252)Cf, ^(235)U and ^(239)Pu were completed and provide information on fission fragment and energy distributions in resonance clusters. Measurements of the (n,α) cross section for ^(147,149)Sm were completed and compared to previously measured data. The new data indicate that the existing evaluations need to be adjusted.
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