Integrated Rocket Simulation of Internal and External Flow Dynamics in an e-Science Environment

The internal and external flowfield variation of a launch vehicle has been simulated in an e-Science environment. To analyze the igniting process of a solid-rocket propellant, a fluid-structure interaction code has been developed using an ALE (arbitrary Lagrangian Eulerian) kinematical description and a staggered fluid-structure interaction algorithm. Also, unsteady motion of a detached rocket booster has been predicted by using an external flow analysis with an aerodynamic-dynamic coupled solver. A Korean e-Science environment designed for aerospace engineering, e-AIRS [15], supplies a user-friendly interface for such individual work and it can advance to an integrated rocket simulation of internal combustion and external flow variation by controlling the execution and data flow of two flow solvers. As a consequence, e-Science facilitates multi-disciplinary collaborative research, and makes individual work more convenient.The current work is a product of the Korea National e-Science project. The authors are grateful to the Korea Institute of Science and Technology Information for their financial support. Also, the authors appreciate the financial supports provided by NSL(National Space Lab.) program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (Grant 20090091724) and the authors are grateful to the Agency for Defence Development for financial support on solid-rocket propellant research.OAIID:oai:osos.snu.ac.kr:snu2009-01/102/0000004648/4SEQ:4PERF_CD:SNU2009-01EVAL_ITEM_CD:102USER_ID:0000004648ADJUST_YN:YEMP_ID:A001138DEPT_CD:446CITE_RATE:1.2FILENAME:article.pdfDEPT_NM:기계항공공학부EMAIL:[email protected]_YN:YCONFIRM:

Trends for the Past 10 Years and International Comparisons of the Structure of Korean Radiation Oncology

Objective: Study aims include determination of nationwide structural characteristics of radiation oncology facilities, types of radiation therapy equipment, availability of human resources and trends and comparisons with previous surveys. Methods: An annual nationwide survey was conducted to collect the statistics of infrastructure since 1997. All requested questionnaires have been identical for 10 years. The questionnaires included status on basic radiation therapy facilities, human resources and radiation therapy equipment. Journal and statistical data reviews were performed to evaluate the structure of other countries. Results: Radiation oncology facilities have steadily increased for 10 years and reached 60 sites in 2006. Also a steady increase of 1.5 times for linear accelerators, 5.8 times for computed tomography simulators and 3.0 times for radiation treatment planning systems was noted. Meanwhile, cobalt-60 teletherapy units and hyperthermia equipment had steadily deceased for 10 years. The number of human resources has steadily increased for the past 10 years, especially for radiation therapy technologists. However, radiation therapy equipment and human resources per population are relatively low compared with advanced countries. Conclusions: This study will assist preparation of the administrative planning policy of radiation oncology and should be useful to indicate the direction of future development and educational training programs in Korea and possibly in other countries

Characterization of Tissue Equivalent Materials Using 3D Printing for Patient-Specific DQA in Radiation Therapy

Three-dimensional printing technology has the advantage of facilitating the construction of complex three-dimensional shapes. For this reason, it is widely used in medical and radiological fields. However, few materials with high electron density similar to that of bone exist for fabricating a human phantom. In this study, commercially available filament materials were used with an FDM 3D printer to perform delivery quality assurance (DQA) and were evaluated for medical use. For the bone filament material, BaSO4 was synthesized in five ratios of 2%, 4%, 6%, 8%, and 10% with 40% PBAT and 50~58% PLA. The electron density for the 3D printing material fabricated was obtained using kV energy CT and compared with the electron density of human organs and bones. The radiation beam properties of the 3D printed structures were analyzed as films for treatment using a linear accelerator. As a result, by changing the infill density of the material, it was possible to produce a material similar to the density of human organs, and a homogeneous bone material with HU values ranging from 371 ± 9 to 1013 ± 28 was produced. The 3D printing material developed in this study is expected to be usefully applied to the development of a patient-specific phantom to evaluate the accuracy of radiotherapy

Human Periodontal Ligament Cell Response to a Newly Developed Calcium Phosphate-based Root Canal Sealer

Objectives: The aim of this study was to investigate the cellular effects of newly developed calcium phosphate based sealers (CAPSEAL I and II) using cultured human periodontal ligament cells (HPDLCs) compared with epoxy resin sealer (AH26; Dentsply, DeTrey, Konstanz, Germany), zinc oxide eugenol [ZOE] sealer (extended working time [EWT]; Kerr Corporation, Orange, CA), and CPC sealer (Sankin apatite sealer; Sankin-kogyo, Tokyo, Japan). Methods: Cell viability by -(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazoliumbromide assay, cell attachment by scanning electron microscopy, osteoblastic differentiation and inflammatory mediators by reverse-transcriptase polymerase chain reaction, Western blotting, and alizarin red staining were evaluated. Results: The cytotoxicities of CAPSEAL I and II were less than those of AH 26 and EWT after 1 and 14 days. Cells on CAPSEAL 1 and II were spread better as compared with those on other sealers. Mineralization after 14 days and the expression of osteoblastic differentiation markers such as alkaline phosphate and osteonectin messenger RNA increased in CAPSEAL I- and II-exposed HPDLCs after 1 and 3 days, whereas the production of inflammatory mediators, including cyclooxygeanse-2, inducible nitric oxide synthetase, and reactive oxygen species (ROS), were lower than in other sealers. Conclusions: These results suggest that both CAPSEAL I and II show less cytotoxicity and inflammatory mediators compared with other sealers and have the potential to promote bone regeneration as root canal sealers. (J Endod 2010;36:1658-1663)Supported by a grant from the Korea Healthcare Technology R&D Project, Ministry for Health, Welfare & Family affairs, Republic of Korea (A084458).

High Density Silver Accordion Nanostructure for Ultra-Sensitive SERS Substrate

2

Activity Evaluation Methodology for the Disposed Medical Linear Accelerators

For the medical linear accelerators (linac) that utilize more than 10 MV of photon energy, components inside the linac head become radioactivate during the 10–15-year operating cycle. Prior to disposal, radioactive waste must be evaluated for activity, and the same procedure should be followed for medical linacs. In the Republic of Korea, regulation and methodology for the radioactivity evaluation for the medical linac is not established yet. In this study, we employed gamma spectroscopy and a survey meter for evaluating the radioactivity of medical linac components. The components of the Siemens linac considered in this study were classified after decommissioning, and dose rates were measured to up to a 5 cm distance from the component surfaces by using a survey meter. Radionuclides from components were detected using an in situ HPGe detector. Based on the type of radionuclides and dose rate, we estimated the radioactivity of the components. We studied the feasibility of the methodology for disposing of radioactive components by using the in situ HPGe detector

The adhesion protein IgSF9b is coupled to neuroligin 2 via S-SCAM to promote inhibitory synapse development

Synaptic adhesion molecules regulate diverse aspects of synapse formation and maintenance. Many known synaptic adhesion molecules localize at excitatory synapses, whereas relatively little is known about inhibitory synaptic adhesion molecules. Here we report that IgSF9b is a novel, brain-specific, homophilic adhesion molecule that is strongly expressed in GABAergic interneurons. IgSF9b was preferentially localized at inhibitory synapses in cultured rat hippocampal and cortical interneurons and was required for the development of inhibitory synapses onto interneurons. IgSF9b formed a subsynaptic domain distinct from the GABA(A) receptor- and gephyrin-containing domain, as indicated by super-resolution imaging. IgSF9b was linked to neuroligin 2, an inhibitory synaptic adhesion molecule coupled to gephyrin, via the multi-PDZ protein S-SCAM. IgSF9b and neuroligin 2 could reciprocally cluster each other. These results suggest a novel mode of inhibitory synaptic organization in which two subsynaptic domains, one containing IgSF9b for synaptic adhesion and the other containing gephyrin and GABA(A) receptors for synaptic transmission, are interconnected through S-SCAM and neuroligin 2.137381sciescopu