Complete Atrioventricular Block Secondary to Acute Pulmonary Embolism: A Case Report

이유실,김무준,서창옥,김한결,김혜리,김계환,박정랑 대한내과학회 2023 대한내과학회 추계학술대회 Vol.2023 No.2

구리 (111) 박막의 급속 열처리 산화로 얻은 고품질 Cu2O (111) 박막

천미연,이유실,김수재,정세영 한국물리학회 2020 새물리 Vol.70 No.11

최근 들어 2.1 eV에서 2.7 eV의 가시광선 영역에서 에너지 간격을 가지고 있어 빛의 흡수도가 높고지구상에 풍부한 구리를 기반으로 하며 독성 또한 가지고 있지 않아 태양광 발전, 광촉매 반응, 물의 광분해, 비선형 광학, 가스 검출 등의 여러 분야에서 집중을 받고 있는 제일 산화구리 Cu2O 박막을 얻고자 하는연구가 많이 진행되고 있다. 본 연구에서는 비교적 간단한 방법인 Cu(111) 박막의 고온 열처리를 통하여높은 결정성을 가지는 Cu2O (111) 박막을 성장하는 연구를 진행하였다. 성장된Cu2O (111) 박막의 XRD 와 SEM, UV-Vis spectroscopy 측정을 통하여 아르곤 분위기 하에 800 ◦C의 온도에서 30 분 열처리한경우 높은 결정성을 가지는 것을 확인하였다, 또한 흡광계수 를 통하여 상온에서 Cu2O (111) 박막의청색 (blue)과 남색 (indigo) 에너지 간격을 얻을 수 있었으며 이것 또한 Cu2O (111) 박막이 높은 결정성을 가지기 때문에 가능하였으며 얻은 값들은 bulk Cu2O구조로부터 얻어진 이론적인 값과 잘 일치하였다. Due to the energy gaps of copper from 2.1 to 2.7 eV, its high light absorption, its nontoxicity and its abundance on the earth, Cu2O is an attractive material for use in various areas such as photovoltaic power generation, photocatalytic reactions, water photolysis, nonlinear optics, and gas sensing. Many researches efforts are being conducted to obtain high-quality Cu2O thin films. In this study, high-quality, epitaxial Cu2O (111) thin films were obtained via a relatively simple method, rapid thermal processes at high temperature of RF sputtered Cu (111) thin film on a sapphire substrate. XRD, SEM and UV-Vis spectroscopy measurements confirmed the high crystallinity of the Cu2O (111) thin film oxidized for 30 minutes at a temperature of 800 ◦C under an atmosphere of argon with 3 ppm of oxygen. Also, because of the high crystal-quality of the Cu2O (111) thin films, blue and indigo energy gaps at room temperature were obtained from the absorption coefficient . The obtained energy band gaps are consistent with the theoretical values obtained from Cu2O bulk structures.

초평탄 구리(111) 박막 위에 성장된 은(111) 박막의 두께에 따른 쌍결정 경계의 전개

김수재,이유실,김영훈,김선제,김영민,정세영 한국물리학회 2023 새물리 Vol.73 No.10

쌍결정 경계 (TB)는 박막의 초기 성장 중에 필연적으로 형성되는 결함이다. 낱알 경계(GB)가 없는 박막을 성장시키는 것도 어려운 주제이지만 TB가 없는 박막을 성장하는 것은 불가능에 가깝다. GB 없이 박막을 성장하는 이상적인 경우, 박막성장 초기에 약 1012개의 TB가 2인치 기판에 나타나지만, 박막이 계속 성장함에 따라 쌍둥이 영역은 동일한 결정학적 배향을 공유하는 더 큰 영역으로 합쳐진다. 일반적인 박막성장 과정에서 엄청난 수의 TB와 GB가 모두 존재하면 이 둘을 구별하는 것이 복잡해지고 필름 두께가 증가함에 따라 달라지는 TB의 거동을 분석하기가 어렵다. 이 연구에서는 GB가 없는 단결정 Ag (은) 박막을 성공적으로 성장시켜 박막 두께가 증가함에 따라 TB의 수가 어떻게 변화하는지 조사하였다. 표면이 원자수준으로 평평한 Cu (구리)(111) 기판의 사용은 Ag 단결정 박막의 성장에 결정적으로 기여한다. 5 nm에서 40 nm 두께의 Ag 박막을 조사한 결과, 박막의 두께가 대략 80 nm에 도달하면 TB가 없는 영역에 도달할 수 있을 것으로 예상된다. Growing thin films without grain boundaries (GBs) is challenging. Furthermore, growing twin boundary (TB)-free thin films has been considered improbable owing to the inevitable formation of TBs during the initial growth of thin films. Initially, about 1012 TBs develop on a 2-inch substrate. Then, the twin domains merge into large ones that share the same crystallographic orientation as the film continues to grow. The presence of large numbers of TBs and GBs occurring in a typical film growth process complicates their differentiation and increases the difficulty in analyzing the behavior of TBs as the film thickness increases. A single-crystal Ag thin film was successfully grown in this study without GBs, allowing the examination of how the number of TBs changes with increasing film thickness. The use of a Cu(111) substrate with an atomically flat surface facilitates the growth of the Ag single-crystal thin film. Our investigation of Ag films ranging from 5 nm to 40 nm in thickness revealed that a region free from TBs can be achieved once the film reaches 80 nm in thickness.

2상 복합재료에 있어서 percolation구조의 2차원 컴퓨터 시뮬레이션

신순기,이유실,이준희,Shin, Soon-Gi,Lee, You-Sil,Lee, Jun-Hee 한국재료학회 2001 한국재료학회지 Vol.11 No.11

Two-dimensional computer simulations were conducted on percolation structure in which second phases of various aspect ratios were arranged in a lattice (matrix). The second phases were randomly arranged in an array with two different computational programs; one prohibiting an overlap among second phases and the other allowing the overlap. From the simulation prohibiting the overlap, it was predicted that a complete path was formed at less amounts of the second phase with higher aspect ratios. In the simulation allowing the overlap, a complete path throughout the array was formed by arranging the second phase of an aspect ratio of 1. 5, 20, 100 with less than 59%, 43%, 19%, 4% in the array, respectively.

급성기 뇌경색 환자에서 뇌 자기공명영상의 확산-관류 불일치가 임상적 예후를 예측할 수 있는가?-rCBV를 중심으로-

전형원,강지혜,이수윤,이유실,강명진,차재관 대한신경과학회 2008 대한신경과학회지 Vol.26 No.4

Background: Diffusion-perfusion mismatch (DPM) on MRI has been considered an ischemic penumbra. However, several reports have demonstrated limitation of DPM on MRI as a predictable marker of the ischemic penumbra. In this study, we investigated the relationship between DPM and the clinical progression in acute ischemic stroke patients. Methods: We consecutively recruited fifty-seven patients showing acute ischemic stroke (within 24 hours) in the middle cerebral artery (MCA) territory. The clinical outcomes were determined by serial measurement of National Institute of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) during 30 days after their ischemic event. We also evaluated the relationship among the parameters of perfusion MRI and the clinical worsening in patients with DPM on initial MRI. Results: Nineteen (33.3%) patients had DPM on MRI within 24 hours after stroke onset. Even though the frequency of clinical worsening for 30 days after stroke onset was higher in DPM group (26%) than in non-DPM group (11%), it did not reach statistical significance (p=0.143). However, extent of MCA stenosis (p<0.001) and time to peak (TTP) delay on MRI (p<0.001) were significantly greater in patients with DPM than in those without DPM. Among several parameters of the perfusion MRI, only relative cerebral blood volume (rCBV) was significantly related to the clinical worsening (62.9±24.7% vs 96.1±19.2%, p=0.007) in patients with DPM. Conclusions: This study shows that DPM on MRI does not always predict the clinical worsening in acute ischemic stroke. To overcome this problem, we should analyze rCBV map based DPM as well as TTP map based DPM. Background: Diffusion-perfusion mismatch (DPM) on MRI has been considered an ischemic penumbra. However, several reports have demonstrated limitation of DPM on MRI as a predictable marker of the ischemic penumbra. In this study, we investigated the relationship between DPM and the clinical progression in acute ischemic stroke patients. Methods: We consecutively recruited fifty-seven patients showing acute ischemic stroke (within 24 hours) in the middle cerebral artery (MCA) territory. The clinical outcomes were determined by serial measurement of National Institute of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) during 30 days after their ischemic event. We also evaluated the relationship among the parameters of perfusion MRI and the clinical worsening in patients with DPM on initial MRI. Results: Nineteen (33.3%) patients had DPM on MRI within 24 hours after stroke onset. Even though the frequency of clinical worsening for 30 days after stroke onset was higher in DPM group (26%) than in non-DPM group (11%), it did not reach statistical significance (p=0.143). However, extent of MCA stenosis (p<0.001) and time to peak (TTP) delay on MRI (p<0.001) were significantly greater in patients with DPM than in those without DPM. Among several parameters of the perfusion MRI, only relative cerebral blood volume (rCBV) was significantly related to the clinical worsening (62.9±24.7% vs 96.1±19.2%, p=0.007) in patients with DPM. Conclusions: This study shows that DPM on MRI does not always predict the clinical worsening in acute ischemic stroke. To overcome this problem, we should analyze rCBV map based DPM as well as TTP map based DPM.