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부산지역 토양의 ^(226,228)Ra, ^(137)Cs 및 ^(40)K 방사능 분포
서범경,성정욱,김현덕,이대원 대한방사선 방어학회 2001 방사선방어학회지 Vol.26 No.4
In this work, we investigated distribution of the natural and artificial radioactive nuclides and level of the regional background in soil in Busan. For 45 points, the environmental radioactivity concentration of Busan surface soil is 14.38 ∼ 57.03 (mean : 33.95) Bq·kg^-1 for ^226Ra, 22.41 ∼ 86.58 (mean : 51.08) Bq·kg^-1 for ^228Ra, 223.64 ∼ 1332.30 (mean : 668.61) Bq·kg^-1 for ^40K and <0.33 ∼ 33.37 (mean : 13.74) Bq·kg^-1 for ^137Cs. Also, in order to investigate vertical distribution for radioactivity, we examined radioactive concentration with mountain height. But there was no correlation between radiaoactivity distribution and mountain height. The ^226Ra/^228Ra and ^228Ra and ^226Ra/^40K concentration ratios were 0.68 ± 19% and 0.06 ± 34%, respectively.
The Effectiveness Evaluation of Helicopter Ambulance Transport among Neurotrauma Patients in Korea
Park, Kyoung Duck,Seo, Sook Jin,Oh, Chang Hyun,Kim, Se Hyuk,Cho, Jin Mo The Korean Neurosurgical Society 2014 Journal of Korean neurosurgical society Vol.56 No.1
Objective : Helicopter ambulance transport (HAT) is a highly resource-intensive facility that is a well-established part of the trauma transport system in many developed countries. Here, we review the benefit of HAT for neurosurgical patients in Korea. Methods : This retrospective study followed neurotrauma patients who were transferred by HAT to a single emergency trauma center over a period of 2 years. The clinical benefits of HAT were measured according to the necessity of emergency surgical intervention and the differences in the time taken to transport patients by ground ambulance transport (GAT) and HAT. Results : Ninety-nine patients were transferred to a single university hospital using HAT, of whom 32 were taken to the neurosurgery department. Of these 32 patients, 10 (31.3%) needed neurosurgical intervention, 14 (43.8%) needed non-neurosurgical intervention, 3 (9.4%) required both, and 11 (34.4%) did not require any intervention. The transfer time was faster using HAT than the estimated time needed for GAT, although for a relatively close distance (<50 km) without ground obstacles (mountain or sea) HAT did not improve transfer time. The cost comparison showed that HAT was more expensive than GAT (3,292,000 vs. 84,000 KRW, p<0.001). Conclusion : In this Korean-based study, we found that HAT has a clinical benefit for neurotrauma cases involving a transfer from a distant site or an isolated area. A more precise triage for using HAT should be considered to prevent overuse of this expensive transport method.
A chaotic micromixer using obstruction-pairs
Park, Jang Min,Seo, Kyoung Duck,Kwon, Tai Hun IOP 2010 JOURNAL OF MICROMECHANICS AND MICROENGINEERING - Vol.20 No.1
<P>A micromixer is one of the most important components for a chemical and/or diagnostic analysis in microfluidic devices such as a micro-total-analysis-system and a lab-on-a-chip. In this paper, a novel chaotic micromixer is developed in a simple design by introducing obstruction-pairs on the bottom of a microchannel. An obstruction-pair, which is composed of two hexahedron blocks arranged in an asymmetric manner, can induce a rotational flow along the down-channel direction due to the anisotropy of flow resistance. By utilizing this characteristic of the obstruction-pair, four mixing units are designed in such a way that three obstruction-pairs induce three rotational flows which result in a down-welling and a hyperbolic point in the channel cross-section. There can be a variety of micromixer geometries by arranging the mixing units in various sequences along the microchannel, and their mixing performances will differ from each other due to different flow characteristics. In this regard, numerical investigations are carried out to predict and characterize the mixing performances of various micromixers. Also experimental verifications are carried out by a flow visualization technique using phenolphthalein and sodium hydroxide solutions in a polydimethylsiloxane-based micromixer.</P>