Contrast-enhanced ultrasound approach to the diagnosis of focal liver lesions: the importance of washout

양현경,김태경,Peter N. Burns,장현정,Yuko Kono,Korosh Khalili,Stephanie R. Wilson 대한초음파의학회 2019 ULTRASONOGRAPHY Vol.38 No.4

Contrast-enhanced ultrasound (CEUS) is a powerful technique for differentiating focal liver lesions (FLLs) without the risks of potential nephrotoxicity or ionizing radiation. In the diagnostic algorithm for FLLs on CEUS, washout is an important feature, as its presence is highly suggestive of malignancy and its characteristics are useful in distinguishing hepatocellular from nonhepatocellular malignancies. Interpreting washout on CEUS requires an understanding that microbubble contrast agents are strictly intravascular, unlike computed tomography or magnetic resonance imaging contrast agents. This review explains the definition and types of washout on CEUS in accordance with the 2017 version of the CEUS Liver Imaging Reporting and Data System and presents their applications to differential diagnosis with illustrative examples. Additionally, we propose potential mechanisms of rapid washout and describe the washout phenomenon in benign entities.

PLD 방법으로 Al2O3(0001) 기판 위에 증착한 Sr2SiO4:Eu3+ 박막의 형광 특성

양현경,이성수,배종성,심규성,정중현 한국물리학회 2005 새물리 Vol.51 No.3

Sr2SiO4 : Eu3+ thin lms were grown on Al2O3(0001) substrates by using pulsed laser deposition at various oxygen pressures and substrate temperatures. The crystallinity and the surface morphology of the lms were investigated using X-ray diraction and atomic force microscope, respectively. The crystallinity and the surface roughness of the lms were highly dependent on the deposition conditions. The photoluminescence (PL) spectra were measured at room temperature by using a luminescence spectrometer and the xcitation caused by a broadband incoherent ultraviolet light source with a dominant excitation wavelength of 254 nm. The luminescence decay time wes measured using a Nd : YAG laser [4th harmonic generation, 5 ns, 10 Hz, 266 nm] and was highly dependent on the photoluminescence properties. The PL spectra exhibited a broad-band emission extending from 565 to 670 nm and appeared to be composed of several overlapping emission bands. The PL peaks were located at 582, 597, and 620 nm and the PL intensity increased with increasing oxygen pressure and reached a maximum at 150 mTorr. This phosphor is promising for applications in at panel displays. Sr$_2$SiO$_4$ : Eu$^{3+}$ 형광체 박막을 pulsed laser deposition (PLD)방법을 이용하여 단결정 Al$_2$O$_3$(0001) 기판 위에 산소 분압과기판 온도를 변화시키며 성장하였다. 박막의 결정성과 표면 형상은 각각X-ray diffraction (XRD)와 atomic force microscopy (AFM)을 이용하여측정하였으며, 박막의 결정성과 표면 거칠기는 증착조건에 밀접한의존성을 보였다. 형광 특성은 실온에서 254 nm의 들뜸광을 방출하는형광 광도계를 이용하여 측정하였으며, 형광 수명은 Nd : YAG 레이저의 4조화파 발진을 이용한 펄스폭이 5 ns인 266 nm 파장을 이용하여측정하였다. 형광 특성은 565 에서 670 nm의 넓은 파장 영역에 걸쳐 발광을 보였으며, 몇 개의 발광 띠들이 겹쳐져서 구성되어짐을 알 수있었다. 형광 피크의 위치는 각각 582, 597, 그리고 619 nm에서나타났으며, 특히 기판 온도가 600 $^\circ$C와 산소 분압이 150mTorr일때 형광 강도가 가장 크게 나타났다. 이 형광체는 flat paneldisplay (FPD)에 적용될 가능성이 있을 것이다.

Photoluminescence investigations of YAG:Eu nanocomposite powder by high-energy ball milling

양현경,정종원,Byung Kee Moon,정중현,Ki-wan Jang,Ho Sueb Lee,Soung Soo Yi 한국물리학회 2009 Current Applied Physics Vol.9 No.2

Europium-doped nanosized yttrium aluminum garnet (YAG) powders and bulk YAG powders were synthesized by using a planetary ball mill and a conventional solid-state reaction method, respectively. The grain size effects of the crystallinity, morphology, structure, and luminescence spectra were investigated by using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and photoluminescence spectroscopy measurements. In the case of nanocrystalline YAG:Eu3+ powder, the luminescence intensity is dominated by the magnetic dipole transition 5D0→7F1 (590 nm) than the 5D0→7F2 forced electric dipole transition (612 nm).

결정성과 표면형상의 변화에 따른 Y0.95Eu0.05VO4 분말과 세라믹 형광체의 형광특성

양현경,김성부,심규성,이성수,정수태,정중현 한국물리학회 2005 새물리 Vol.50 No.3

The surface morphologies, crystallinities, and luminecences of Y0:95Eu0:05VO4 powder and ceramic samples were investigated by changing the sintering temperature. X-ray diraction showed that as sintering temperature was measured was 800 to 950 C, the particle size of the samples became uniform and increased, surface morphology became nearly spherical, and crystallinity was improved, The photoluminecences (PL) Y0:95Eu0:05VO4 powder and ceramic sintered at 950 C was more intense than the PL from the samples sntered at 800 and 900 C. The increase in the PL was due to not only the improved crystallinity but also the increased of particle size and the change in the surface morphology. The luminecent characterestics of phosphors depend on their crystallinity and their surface morphology, both of which change with the sintering temperature.

Gd1-xVO4:Eu3+x (x=0.03) 분말과 세라믹 형광체의 형광특성

양현경,이성수,배종성,심규성,정중현 한국물리학회 2004 새물리 Vol.49 No.6

GdVO4 : Eu3+ powder and ceramic samples were prepared from stoichiometric amounts of thesurface structure, the crystallinity and the PL spectrum were measured as functions of the sintering temperature. As the sintering temperature was increased (800, 900 and 950 C) the grain sizeincreased, and the crystallinity improved. PL intensity of the powder and the ceramic samples sintered at 950 C were 1.6 times brighter than that of the samples sintered at 800 C and 1.3 times brighter than that of the samles sintered at 900 C. The results of the experiments with the GdVO4 : Eu3+ powder and ceramic samples prove that our samples were high-quality red-emission phosphor.

Development of an Online Radiology Case Review System Featuring Interactive Navigation of Volumetric Image Datasets Using Advanced Visualization Techniques

양현경,우현식,조재민,이민희,김보형,서진욱,정주현,강흥식,이경호 대한영상의학회 2015 대한영상의학회지 Vol.73 No.5

Purpose: To develop an online radiology case review system that allows interactive navigation of volumetric image datasets using advanced visualization techniques. Materials and Methods: Our Institutional Review Board approved the use of the patient data and waived the need for informed consent. We determined the following system requirements: volumetric navigation, accessibility, scalability, undemanding case management, trainee encouragement, and simulation of a busy practice. The system comprised a case registry server, client case review program, and commercially available cloud-based image viewing system. Results: In the pilot test, we used 30 cases of low-dose abdomen computed tomography for the diagnosis of acute appendicitis. In each case, a trainee was required to navigate through the images and submit answers to the case questions. The trainee was then given the correct answers and key images, as well as the image dataset with annotations on the appendix. After evaluation of all cases, the system displayed the diagnostic accuracy and average review time, and the trainee was asked to reassess the failed cases. The pilot system was deployed successfully in a hands-on workshop course. Conclusion: We developed an online radiology case review system that allows interactive navigation of volumetric image datasets using advanced visualization techniques.

Al3+ 이온 첨가에 의한 MTiO3:Pr3+와(M = Ca, Sr) 분말 형광체의 형광특성

양현경,이성수,장준규,정중현 한국물리학회 2006 새물리 Vol.52 No.3

A correlation between the surface morphology, the crystallization, and the luminescence properties on Al-doped CaTiO$_3$ : Pr$^{3+}$ and SrTiO$_3$ : Pr$^{3+}$ phosphors has been investigated. Al doping affected the uniformity and the size of the particles. Also, the crystallinity of the powders was improved by Al doping. The luminescence intensity for Al-doped CaTiO$_3$ : Pr$^{3+}$ and SrTiO$_3$ : Pr$^{3+}$ phosphors was enhanced not only by the improved of crystallinity but also by the increased particle size and the changed surface morphology induced by Al doping. The luminescence peak intensities radiated from the $^1$D$_2$ $\rightarrow$ $^3$H$_4$ transitions of the CaTiO$_3$ : Pr$^{3+}$ and the SrTiO$_3$ : Pr$^{3+}$ powders appeared at 613 and 615 nm, respectively. The CaTiO$_3$ : Pr$^{3+}$ powders showed luminescence characteristics that were superior to those of the SrTiO$_3$ : Pr$^{3+}$ powders. For the CL spectra, Al doping increased the luminescence efficiency and made the spectra stable under variations in the acceleration voltage. CaTiO$_3$ : Pr$^{3+}$와 SrTiO$_3$ : Pr$^{3+}$ 분말에 Al$^{3+}$ 이온을 첨가하여 표면구조와 결정성 그리고 광학적 형광특성 및 음극선 형광특성을 조사하였다. Al$^{3+}$ 이온의 첨가로 입자들이 균일해지며 크기도 증가하였고, $X$-선 회절상을 통하여 결정성도 향상되어짐을 확인하였다. 또한, Al$^{3+}$ 이온을 첨가함으로 형광의 세기가 증가하였는데, 이것은 Al$^{3+}$ 이온을 첨가함으로 분말의 결정성의 향상뿐만 아니라 입자들의 크기 증가 및 표면 거칠기의 변화에 의한 것임을 알 수 있었다. 주발광선은 Pr$^{3+}$의 $^1$D$_2$ $\rightarrow$ $^3$H$_4$전이에 의한 613 nm와 615 nm으로 Al$^{3+}$ 이온의 첨가에 무관하였으며, SrTiO$_3$ : Pr$^{3+}$ 분말보다 CaTiO$_3$ : Pr$^{3+}$ 분말에서 전반적으로 형광특성이 우수하였다. 그리고 Al$^{3+}$ 이온을 첨가함으로 음극선 형광효율이 증가할 뿐만 아니라 높은 전압에서 형광은 더욱 안정되었다.

Temperature-Dependent Luminescence Characteristics of Al-Doped CaTiO3:Pr3+ Thin Films

양현경,이성수,전병억,Byung Chun Choi,문병기,Chang Hoon Kim,배종성,김중환,정중현 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III

Al-doped CaTiO3:Pr3+ luminescent thin films have been grown on Al2O3 (0001) substrates by using a pulsed laser deposition technique at an oxygen pressure of 300 mTorr for substrate temperatures of 500, 600, and 700 C. The mechanism for the enhancement of the red emission efficiency from the Al-doped CaTiO3:Pr3+ thin films has been investigated for various substrate temperature. The influence of the substrate temperature on the crystallization, the surface morphology, and the luminescent properties of Al-doped CaTiO3:Pr3+ thin films are discussed. Their luminescent and excitation properties have been evaluated at room temperature by using a luminescence spectrometer and a broadband incoherent ultraviolet light source with a dominant excitation wavelength of 317 nm, respectively. The enhancement of the luminescence for Al-doped films may result not only from the improved crystallinity but also from reduced internal reflections caused by rougher surfaces. The increase in the rms roughness with substrate temperatures is attributed to the enhanced grain size. The Al-doped films grown at a substrate temperature of 700 C with fewer grain boundaries exhibited superior PL properties. Also, the luminescent intensity and the surface roughness of the films exhibited similar behaviors as functions of the substrate temperature.bt

상업공간에 도입된 건축스테인드글라스의 효과 및 가능성에 대한 연구

양현경 미술사문화비평학회 2015 미술사문화비평 Vol.6 No.-

유리를 매체로 하여 빛과 색을 종합시킨 스테인드글라스는 그 시작부터 건축적인 예 술이었다. 고딕건축을 통하여 최고조에 이른 스테인드글라스가 르네상스의 자연주의, 사실주의 회화와 벽화의 전개로 차츰 쇠퇴하면서 거의 잊혀 지는듯 하였으나 20세기 초 부터 다시 부각을 드러내기 시작하였다. 본 연구에서는 일반건축 중에서도 상업공간에 도입된 건축스테인드글라스로 연구범위를 좁혔으며, 상업공간에 도입된 국내외 현황을 서술하고 앞으로의 발전 가능성에 대해 알아보았다. 이 논문을 통해 국내외의 건축스테인드글라스의 현황을 정확히 파악하여 앞으로의 발전방향을 잡고 상업공간 뿐만 아니라 스테인드글라스의 도입이 필요한 여러 일반건 축물들에 대한 연구 또한 끊임없이 해나가야 할 계기가 생겼다. 또한 기존에 있는 제작 기법을 바탕으로 새로운 기법연구와 건축을 포함한 여러 전문가들의 협업으로 좀 더 전문적인 지식으로 스테인드글라스를 연구하고 발전시키는데 본 논문의 의미가 있다 하겠다. The stained glass that combined light and color by the medium of glass was the architectural art from the beginning itself. The stained glass which reached its peak through Gothic architecture gradually declined with the development of naturalism and realism paintings and mural paintings during the Renaissance period. It reached the point of being almost forgotten, but began to emerge early in the 20th century. This study narrowed the research range to general architecture, especially architectural stained glass introduced to commercial space and described the internal and external status of stained glass introduced to commercial space and looked at its development possibility. This study provides an opportunity to make a study on various ordinary architectural buildings that need to introduce stained glass as well as commercial space by identifying the current status of architectural stained glass in Korea as exactly as possible and setting up future development directions. Furthermore, this study is significant in that stained glass can be studied and developed with more specialized knowledge through cooperation with various experts - research on new technique and architecture - based on the existing manufacturing techniques.

고에너지 볼 밀링 방법을 이용한 Sr3SiO5:Eu2+ 백색 LED용 분말 형광체의 형광 특성

양현경,정중현,김윤식,박진우,서세민,최수원,하재민,허성민,박용대 한국물리학회 2012 새물리 Vol.62 No.7

Sr_3SiO_5:Eu^2+ powder phosphors were synthesized by using the high-energy ball-milling method. The surface morphology,crystallinity, and luminecence of the Sr_3SiO_5:Eu^2+ powder phosphors were investigated for changing sintering temperature. The crystalline phases and the phase transitions were examined with X-ray diffraction (XRD) for various sintering temperatures. As the sintering temperature was increased (1100, 1200, 1300 and 1400℃) the particle size increased, and the crystallinity improved. In addition, the phase transition from Sr_2SiO_4 to Sr_3SiO_5 was examined at sintering temperatures above 1300℃. The sample showed a broad excitation band from 200 to 500nm and a broad band emission peak at 566 nm. The Photoluminescence from the powder sintered at 1400 ℃ was 2.5 times brighter than that from the samples sintered at 1300℃. Sr_3SiO_5:Eu^2+ 분말 형광체는 고에너지 볼 밀링 방법을이용하여 합성하였으며, 소결온도에 따른 표면구조와 결정성 그리고형광특성을 조사하였다. X-선 회절을 통하여 소결온도에 따른 결정구조및 상변화를 분석하였다. 소결온도가 1100, 1200, 1300 그리고 1400℃로 증가함에 따라 분말입자의 크기가 증가하였으며, 결정화가잘 되었다. 또한, 소결온도 1300 ℃이상에서 Sr_2SiO_4에서Sr_3SiO_5로 상변화가 일어남을 확인하였다. 형광 스펙트럼에서 200~ 500 nm의 넓은 영역의 PLE 스펙트럼과 566 nm의 황색 PL 스펙트럼을 확인하였다. 소결온도가 1300℃에서 1400℃로 증가할 때, 형광세기가 2.5배 증가하였다.