http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Choi, Sunghoon,Lee, Seungwan,Lee, Haenghwa,Lee, Donghoon,Choi, Seungyeon,Shin, Jungwook,Seo, Chang-Woo,Kim, Hee-Joung Elsevier 2017 Nuclear Instruments & Methods in Physics Research. Vol.848 No.-
<P><B>Abstract</B></P> <P>Digital tomosynthesis offers the advantage of low radiation doses compared to conventional computed tomography (CT) by utilizing small numbers of projections (~80) acquired over a limited angular range. It produces 3D volumetric data, although there are artifacts due to incomplete sampling. Based upon these characteristics, we developed a prototype digital tomosynthesis R/F system for applications in chest imaging. Our prototype chest digital tomosynthesis (CDT) R/F system contains an X-ray tube with high power R/F pulse generator, flat-panel detector, R/F table, electromechanical radiographic subsystems including a precise motor controller, and a reconstruction server. For image reconstruction, users select between analytic and iterative reconstruction methods. Our reconstructed images of Catphan700 and LUNGMAN phantoms clearly and rapidly described the internal structures of phantoms using graphics processing unit (GPU) programming. Contrast-to-noise ratio (CNR) values of the CTP682 module of Catphan700 were higher in images using a simultaneous algebraic reconstruction technique (SART) than in those using filtered back-projection (FBP) for all materials by factors of 2.60, 3.78, 5.50, 2.30, 3.70, and 2.52 for air, lung foam, low density polyethylene (LDPE), Delrin<SUP>®</SUP> (acetal homopolymer resin), bone 50% (hydroxyapatite), and Teflon, respectively. Total elapsed times for producing 3D volume were 2.92s and 86.29s on average for FBP and SART (20 iterations), respectively. The times required for reconstruction were clinically feasible. Moreover, the total radiation dose from our system (5.68mGy) was lower than that of conventional chest CT scan. Consequently, our prototype tomosynthesis R/F system represents an important advance in digital tomosynthesis applications.</P>
Ischemic heart diseases: Current treatments and future
Choi, Donghoon,Hwang, Ki-Chul,Lee, Kuen-Yong,Kim, Yong-Hee Elsevier 2009 Journal of controlled release Vol.140 No.3
<P><B>Abstract</B></P><P>Ischemic heart disease is a rapidly increasing common cause of death in the world. This disease is the insufficient status of oxygen within the cardiac muscles due to an imbalance between oxygen supply and demand, and a cardiac disease that occurs as a result of coronary artery stenosis. Conventional surgery-based therapy for the treatment of ischemic heart diseases has been advanced with biopharmaceutical-based therapy, such as protein, gene and cell therapy. The conventional medical therapy focuses on the use of drug eluting stents, coronary-artery bypass-graft surgery and anti-thrombosis. Biopharmaceutical-based therapies including recombinant protein therapy, gene therapy and cell transplantation are recognized as promising approaches in inducing neovascularization and improving collateral blood flow in the ischemic heart. This review explores the current status and future of the treatment of ischemic heart diseases with conventional medical therapy, biopharmaceutical-based therapy focused on the proteins and polymeric hydrogels for delivery of therapeutic proteins.</P> <P><B>Graphical abstract</B></P><P><ce:figure></ce:figure></P>
Choi, Sun Young,Won, Jong Yun,Lee, Do Yun,Choi, Donghoon,Shim, Won-Heum,Lee, Kwang-Hun The Korean Society of Radiology 2010 KOREAN JOURNAL OF RADIOLOGY Vol.11 No.1
<P><B>Objective</B></P><P>The purpose of this study was to evaluate the technical feasibility and clinical efficacy of percutaneous transabdominal treatment of endoleaks after endovascular aneurysm repair.</P><P><B>Materials and Methods</B></P><P>Between 2000 and 2007, six patients with type I (n = 4) or II (n = 2) endoleaks were treated by the percutaneous transabdominal approach using embolization with N-butyl cyanoacrylate with or without coils. Five patients underwent a single session and one patient had two sessions of embolization. The median time between aneurysm repair and endoleak treatment was 25.5 months (range: 0-84 months). Follow-up CT images were evaluated for changes in the size and shape of the aneurysm sac and presence or resolution of endoleaks. The median follow-up after endoleak treatment was 16.4 months (range: 0-37 months)</P><P><B>Results</B></P><P>Technical success was achieved in all six patients. Clinical success was achieved in four patients with complete resolution of the endoleak confirmed by follow-up CT. Clinical failure was observed in two patients. One eventually underwent surgical conversion, and the other was lost to follow-up. There were no procedure-related complications.</P><P><B>Conclusion</B></P><P>The percutaneous transabdominal approach for the treatment of type I or II endoleaks, after endovascular aneurysm repair, is an alternative method when conventional endovascular methods have failed.</P>
A Low-power Neural Signal Acquisition Analog Front-end IC for Closed-loop Neural Interfaces
Donghoon Choi,Hyouk-Kyu Cha 대한전자공학회 2022 Journal of semiconductor technology and science Vol.22 No.5
This paper presents an ultra-low-power neural signal recording analog front-end IC (AFE) which is comprised of a low-noise amplifier (LNA) followed by a programmable gain amplifier (PGA). To achieve good overall performance while handling stimulation artifacts in closed-loop neural interface systems, the proposed LNA is designed for moderate gain, low input noise, and, good linearity while the PGA is included for additional gain and tunable bandwidth functions. Implemented using 0.18-μm CMOS process, the AFE achieves a measured closed-loop gain of 20 to 40 dB and integrated input referred noise of 3.39 μVrms over 1 Hz to 6.5 kHz. The IC consumes 1.49 μW at 1-V supply and the noise efficiency factor is 1.93. For less than 1% total harmonic distortion, the AFE can accommodate up to 60 mVpp and 280 mVpp of differential and common-mode stimulation artifacts, respectively.
Effective detective quantum efficiency of two detectors in a prototype digital breast tomosynthesis
Choi, Seungyeon,Choi, Sunghoon,Lee, Donghoon,Kim, Ye-seul,Choi, Young-Wook,Kim, Hee-Joung Elsevier 2019 Optik Vol.178 No.-
<P><B>Abstract</B></P> <P>Digital breast tomosynthesis (DBT) system is a novel imaging modality that strongly depends on the detector performance. The effective detective quantum efficiency (eDQE) is a newly accepted system of performance analysis metric that solves the disadvantages of conventional DQE evaluations, which do not consider clinical operating conditions. To evaluate the eDQE, we used the direct-conversion based Anrad detector and the indirect-conversion based Dexela detector. Our aim is to study the performance of such detectors when they are mounted on a prototype DBT system. The prototype DBT system consists of a CsI(Tl) scintillator/CMOS-based flat panel digital detector and an a-Se based direct conversion detector developed by the Korea Electrotechnology Research Institute (KERI). The performance of the two detectors was compared on the basis of scatter fraction, transmission factor, effective modulation transfer function (eMTF), and effective normalized noise power spectrum (eNNPS). As a result, the Dexela detector is characterized by a decreasing eNNPS trend as the spatial frequency increases, whereas the Anrad eNNPS looks almost independent of the spatial frequency. The eMTF was found to be higher in the Anrad detector compared to that in the Dexela one for all frequencies. The eDQE values at 1 cycle/mm (low frequency) were 0.11 and 0.17 for the Anrad and Dexela detectors, respectively, and the values of the spatial frequency <SUB> f e D Q E ( 0.1 ) </SUB> , corresponding to eDQE = 0.1, were 1.25 and 2.81 cycles/mm for the Anrad and Dexela detectors, respectively. The Dexela detector also presented a higher contrast-to-noise ratios (CNRs) for all different sizes of μCa groups, thus demonstrating overall better eDQE results in imaging performance compared to the Anrad detector.</P>
Comparison study of image quality and effective dose in dual energy chest digital tomosynthesis
Lee, Donghoon,Choi, Sunghoon,Lee, Haenghwa,Kim, Dohyeon,Choi, Seungyeon,Kim, Hee-Joung Elsevier 2018 Radiation physics and chemistry Vol.148 No.-
<P>The present study aimed to introduce a recently developed digital tomosynthesis system for the chest and describe the procedure for acquiring dual energy bone decomposed tomosynthesis images. Various beam quality and reconstruction algorithms were evaluated for acquiring dual energy chest digital tomosynthesis (CDT) images and the effective dose was calculated with ion chamber and Monte Carlo simulations. The results demonstrated that dual energy CDT improved visualization of the lung field by eliminating the bony structures. In addition, qualitative and quantitative image quality of dual energy CDT using iterative reconstruction was better than that with filtered backprojection (FBP) algorithm. The contrast-to-noise ratio and figure of merit values of dual energy CDT acquired with iterative reconstruction were three times better than those acquired with FBP reconstruction. The difference in the image quality according to the acquisition conditions was not noticeable, but the effective dose was significantly affected by the acquisition condition. The high energy acquisition condition using 130 kVp recorded a relatively high effective dose. We conclude that dual energy CDT has the potential to compensate for major problems in CDT due to decomposed bony structures, which induce significant artifacts. Although there are many variables in the clinical practice, our results regarding reconstruction algorithms and acquisition conditions may be used as the basis for clinical use of dual energy CDT imaging.</P>
최동훈 ( Donghoon Choi ),엄정호 ( Jungho Um ),윤화묵 ( Hwa-mook Yoon ),최윤수 ( Yun-soo Choi ),이민호 ( Minho-lee ),이원구 ( Won-goo Lee ),송사광 ( Sa-kwang Song ),정한민 ( Hanmin Jung ) 한국정보처리학회 2012 한국정보처리학회 학술대회논문집 Vol.19 No.2
식물 염기 서열 분석은 동물에 비해 유전체가 길고 데이터 양이 많아 특별한 전략을 요구하고 있다. 본 논문은 FCLA 전략을 지원하기 위한 데이터 분석 플랫폼의 개발에 대해 서술한다.
최동훈(Donghoon Choi),한승은(Seungeun Han),추혁진(Hyeok-Jin Chu),김인주(Injoo Kim),김성동(Sungdong Kim) 한국마이크로전자및패키징학회 2021 마이크로전자 및 패키징학회지 Vol.28 No.4
상압 수소 플라즈마 전처리가 구리-구리 직접 본딩에 미치는 영향에 대해서 조사하였다. 상압 수소 플라즈마 처리를 통해 구리 박막의 표면 산화층을 환원시킬 수 있었음을 GIXRD 분석을 통해 확인하였다. 플라즈마 파워가 크고 플라즈마 처리 시간이 길수록 환원력 및 표면 거칠기 관점에서 효과적이었다. DCB를 이용한 계면 결합 에너지 측정에서 상압 수소 플라즈마 전처리 후 300℃에서 본딩한 경우 양호한 계면 결합 에너지를 나타내었으나, 본딩 온도가 낮아질수록 계면 결합 에너지가 낮아져 200℃에서는 본딩이 이루어지지 않았다. 습식 전처리의 경우 250℃ 이상에서 본딩한 경우 강한 결합력을 보였으며, 200℃에서는 낮은 계면 결합 에너지를 나타내었다. We investigated the effects of atmospheric hydrogen plasma treatment on Cu-Cu direct bonding. Hydrogen plasma was effective in reducing the surface oxide layer of Cu thin film, which was confirmed by GIXRD analysis. It was observed that larger plasma input power and longer treatment time were effective in terms of reduction and surface roughness. The interfacial adhesion energy was measured by DCB test and it was observed to decrease as the bonding temperature decreased, resulting in bonding failure at bonding temperature of 200℃. In case of wet treatment, strong Cu-Cu bonding was observed above bonding temperature of 250℃.