http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
임명상(Myeongsang Lim),이승현(Seunghyeon Lee),신진호(Jinho Shin),차정희(Jeonghee Cha),김정욱(Jeonguk Kim),성동욱(Dongwuk Seong) 대한영상의학기술학회 2014 대한영상의학기술학회 논문지 Vol.2014 No.1
목 적 : 화질과 피폭선량에 영향을 주는 관전압, 관전류 및 조사시간, 격자, 부가필터, 거리, 조사야 등과 같은 인자들 중에 특히 촬영 관전압과 부가필터는 화질의 대조도와 피폭선량을 결정하는 선질에 중요한 역할을 한다. DR system의 발달로 dynamic range가 넓어진 만큼 적정 선량으로도 동일한 image quality를 얻을 수 있기에 기존에 CR system에서 사용하던 촬영조건이 아닌 DR system에서의 Pelvis AP에 맞는 진단참고준위를 만들고 환자피폭선량 감소를 위한 방안을 모색 하고자 한다. 대상 및 방법 : “식약청에서 발간한 일반촬영검사의 환자선량 가이드라인”에 있는 pelvis AP 촬영조건 통계를 바탕으로 table을 작성하였다. DR system philips Digital Diagnost 장비를 사용하였고 오차를 줄이기 위해 rando phantom 위에 광자극발광선량계(OSL:optically stimulated luminescence)를 3개씩 올려놓고 각 촬영조건에 따라 added filter를 바꿔가며 ESD, DAP, EI값을 측정하였으며 PCMCX progam으로 유효선량을 산출 하였다. 또한 image 평가를 위해 Image J program으로 histogram을 비교하였다. 결 과 : (73, 77, 81, 88)kVp와 (16, 20, 25, 32)mAs에 대한 필터조합유무에 따라, 85kVp에선 non-filter에 대한 감소비율이 Al 2mm, Al1+Cu0.1mm, Al1+Cu0.2mm의 표면입사선량이 각각 37%, 52%, 67%씩 감소하며 kVp가 한 단계 낮춰질수록 non-filter에 대한 감소비율이 동일하게 1~2%씩 증가하며 유효선량 또한 촬영조건이 낮을수록, filter를 사용할수록 감소한다. 또한 촬영조 건과 필터조합이 다르더라도 노출지수(EI:exposure index)값이 같을 경우 histgram이 일치하는데 이는 같은 image임에도 선량이 차이가 난다는 걸 알 수 있다. 결 론 : 이번 실험을 통해 pelvis AP 검사시 77kVp 16mAs addede filter Al1+Cu0.2일 때 가장 이상적인 image와 0.504mGy의 피폭선량으로, 2012년도에 식약청에서 발간한“일반촬영 가이드라 인의 pelvis AP 권고량”이 3.42mGy인걸 감안하면 상당히 감소시킬 수 있었다. Purpose: Tube voltage and added filter play an important role in radiation quality that determines definition contrast and exposure dose amount among the elements affecting definition and exposure dose such as tube voltage, tube current, examination time, grid, added filter, distance, and irradiation. As DR system advancement has widened the dynamic range, now we can gain the identical image quality with more efficient dose amount. In this recognition, this research seeks to establish a new set of diagnose reference more appropriate for the pelvis AP in DR system than the previous imaging requirements in the CR system while exploring how to reduce a patient’s exposure dosage. Subject and method: We, for the purpose of this research, made tables based on the statistics on pelvis AP imaging requirements described in the guidelines for patients’ exposure dose in general imaging examinations published by the Food and Drug Administration of South Korea. DR system Philips Digital Diagnost was used herein. To reduce errors, we placed 3 sets of Optically Stimulated Luminescences (OSL) on Rando Phantom and measured ESD, DAP and EI values by changing added filters according to each imaging requirement. The PCMCX program was used to calculate effective exposure dose. Also to evaluate the images, we compared histograms through the Image J program. Findings: According to the filter combination existence regarding (73, 77, 81, 88)kVp and (16, 20, 25, 32)mAs, 85kVp showed non-filter reduction ratios of Al 2mm, Al1+Cu0.1mm, Al1+Cu0.2mm ESD values, 37%, 52%, 67%, respectively. For every kVp reduction by a notch, non-filter reduction ratio increased by 1~2% identically. And reduction became more apparent as the effective dose or imaging requirements were lower and more filters were used. Even though the imaging requirements and filter combination were different, if the Exposure Index (EI) was identical, the histogram coincided, signaling that the dose varies even in the same images. Conclusion: This research has found that the ideal pelvis AP examination image and exposure dose of 0.519mGy was obtained when 77kVp 16mAs added filter Al1+Cu0.2. Considering that 3.42mGy was the recommended amount for pelvis AP in the 2012 guidelines for general imaging examinations by the FDA of the country, the level found in this research means a significant reduction from it.
Metal ions affect the formation and stability of amyloid β aggregates at multiple length scales
Lee, Myeongsang,Kim, Jae In,Na, Sungsoo,Eom, Kilho The Royal Society of Chemistry 2018 Physical chemistry chemical physics Vol.20 No.13
<P>Amyloid β (Aβ) aggregates, which are a hallmark for neurodegenerative disease, are formed through a self-assembly process such as aggregation of Aβ peptide chains. This aggregation process depends on the solvent conditions under which the proteins are aggregated. Nevertheless, the underlying mechanism of the ionic effect on the formation and stability of amyloid aggregates has not been fully understood. Here, we report how metal ions play a role in the formation and stability of Aβ aggregates at different length scales, <I>i.e.</I> oligomers and fibrils. It is shown that the metal (<I>i.e.</I> zinc or copper) ion increases the stability of Aβ oligomers, whereas the metal ion reduces the stability of Aβ fibrils. In addition, we found that zinc ions are able to more effectively destabilize fibril structures than copper ions. Metal ion-mediated (de)stabilization of Aβ oligomers (or fibrils) is attributed to the critical effect of the metal ion on the β-sheet rich crystalline structure of the amyloid aggregate and the status of hydrogen bonds within the aggregate. Our study sheds light on the role of the metal ion in stabilizing the amyloid oligomers known as a toxic agent (to functional cells), which is consistent with clinical observation that high concentrations of metal ions are found in patients suffering from neurodegenerative diseases.</P>
Mechanical behavior comparison of spider and silkworm silks using molecular dynamics at atomic scale
Lee, Myeongsang,Kwon, Junpyo,Na, Sungsoo The Royal Society of Chemistry 2016 Physical chemistry chemical physics Vol.18 No.6
<P>Spider and silkworm silk proteins have received much attention owing to their inherent structural stability, biodegradability, and biocompatibility. These silk protein materials have various mechanical characteristics such as elastic modulus, ultimate strength and fracture toughness. While the considerable mechanical characteristics of the core crystalline regions of spider silk proteins at the atomistic scale have been investigated through several experimental techniques and computational studies, there is a lack of comparison between spider and silkworm fibroins in the atomistic scale. In this study, we investigated the differences between the mechanical characteristics of spider and silkworm fibroin structures by applying molecular dynamics and steered molecular dynamics. We found that serine amino acids in silkworm fibroins not only increased the number of hydrogen bonds, but also altered their structural characteristics and mechanical properties.</P>