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Deep Enteroscopy: Which Technique Will Survive?
전성란,Jin-Oh Kim 대한소화기내시경학회 2013 Clinical Endoscopy Vol.46 No.5
The advent of deep enteroscopy (DE) has dramatically changed diagnostic and therapeutic approaches to small bowel diseases. Unlike capsule endoscopy, which is unable to obtain biopsies or treat a disease, DE techniques have diagnostic and therapeutic capabilities. Double-balloon enteroscopy (DBE) was introduced in 2001, and single-balloon enteroscopy (SBE) and spiral enteroscopy (SE) were subsequently developed for small bowel investigation. In published reports comparing these different enteroscopy techniques, most comparative parameters (depth of insertion, complications, learning curve, diagnostic yield, and therapeutic yield) were comparable among DBE, SBE, and SE. However, the procedure duration appears to be shorter for SE than for DBE and SBE. The rate of complete enteroscopy is clearly superior for DBE, compared with SE and SBE. Because these results do not indicate an increase in diagnostic or therapeutic yield, the clinical impact of complete enteroscopy remains controversial. According to previous studies, the three DE methods seem to be equally effective and safe in the clinical setting. Although larger randomized controlled trials are needed to evaluate the procedural characteristics and clinical impact, the selection of an enteroscopic technique should be based on availability and the endoscopist’s experience.
전성란,손성진,박시현 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.11
We report the growth and the characterization of both quaternary AlGaInN bulk layers andAlGaInN/InGaN multiple-quantum-well (MQW) layers grown by using metal-organic chemical vapordeposition for high-efficiency ultraviolet light-emitting diodes (UV LEDs). Inclusion of a smallfraction of indium in the AlGaInN layer was found to reduce the number of structural defectsand the strain in the layer. From the intensities of temperature-dependent photoluminescence andtime-resolved photoluminescence, the internal quantum efficiency at 300 K was obtained as 60%for the sample grown with a quaternary AlGaInN barrier in the MQWs and 25% for the samplewith a ternary AlGaN barrier. The dominant optical transition in the AlGaInN/InGaN MQWswas considered to be caused by localized exciton recombination and reduction of the strain in theMQW stack, with indium incorporation in the barriers, resulting in the longest decay lifetime fromquaternary AlGaInN alloys. We measured the optical output power from the UV LED device grownwith quaternary AlGaInN barriers. The LEDs reached a maximum output power of 50.6 mW anda wall-plug efficiency of 2.99% under an input current level of 400 mA.
저압 MOCVD법에 의한 (100)-GaAs 기판 위의 Ga_xIn(1-x)P 성장과 특성
전성란,손성진,조금재,박순규,김영기 全北大學校 基礎科學硏究所 1994 基礎科學 Vol.17 No.-
x??0.51인 Ga_xIn_(1-x)P 에피층을 저압 MOCVD 성장법으로 TEGa(triethylgallium), TMIn(trimethylindium) 등의 MO(metalorganic) 원료와 PH_3(phosphine)를 사용하여 GaAs(100) 기판 위에 성장하였다. 성장조건에 의한 표면 morphology, 결정결함, 성분비, PL spectra, 운반자 농도와 이동도 및 DLTS spectra와 같은 성장층의 특성을 관찰하였다. 650℃의 성장온도와 V/Ⅲ 비, 즉 TEGa와 TMIn 두 원료의 유량에 대한 PH_3의 유량비가 160∼220일 때 가장 좋은 성장표면을 나타내었다. 성장률은 PH_3의 유량변화에 아무런 영향을 받지 않음을 알 수 있었다. Ga_0.51In_0.49P 에피층과 기판의 격자상수 차에 의한 격자 부정합 Δa_⊥/a_0은 약 (3.7∼8.9)×10 exp (-4)이었으며 실온과 5K에서 에피층의 PL 피크 에너지는 각각 1.85 eV와 1.9 eV였다. 성장층의 운반자 농도와 이동도는 V/Ⅲ 비에 따라 달라지는데 그 비가 120에서 220으로 증가함에 따라 농도는 1.8×10 exp (16) ㎝^-3에서 8.2×10 exp (16) ㎝^-3로 증가하였고 이동도는 1010 ㎝/V·sec에서 366 ㎝/V·sec로 감소하였다. Epitaxial layers of Ga_xIn_(1-x)P with x??0.51 were grown on the GaAs substrates oriented 2℃ off (100) toward <110> by low pressure MOCVD growth technique using triethylgallium (TEGa), trimethylindium (TMIn) and phosphine (PH_3). Surface morphology, crystal defects, composition, photoluminescence spectra, carrier concentration and DLTS spectra of the grown layers were investigated. Good quality epilayers with featureless surface were obtained at growth temperature of 650℃ and V/Ⅲ ratio, i.e., PH_3 flow rate divided by the sum of TEGa and TMIn flow rates, of 160 to 220. The growth rate turned out to have no dependence on phosphine flow rate. The lattice mismatchs Δa_⊥/a_0 between grown Ga_0.51In_0.49P epilayer and GaAs substrate were (3.7∼8.9)×10 exp (-4) and the PL peak energies of the epitaxial layer at room temperature and 5K were 1.85 eV and 1.9 eV, respectively. With increasing V/Ⅲ ratio i.e., phosphine flow rate, from 120 to 220, the carrier density and mobility of undoped epitaxial layers increased from 1.8×10 exp (16) to 8.2×10 exp (16) ㎝^-3 and decreased from 1010 to 366 ㎝/V·sec, respectively.
만성B형간염에서 바이러스 돌파현상의 지연 예측인자로써 24주 이내의 HBV DNA 소실
전성란 ( Seong Ran Jeon ),장재영 ( Jae Young Jang ),정승원 ( Soung Won Jeong ),박승훈 ( Seung Hoon Park ),이세환 ( Sae Hwan Lee ),김상균 ( Sang Gyune Kim ),천영국 ( Young Koog Cheon ),김영석 ( Young Seok Kim ),조영덕 ( Young De 대한소화기학회 2011 대한소화기학회지 Vol.58 No.1
Background/Aims: Sustained HBV DNA reduction is necessary for biochemical remission, histological improvement, and prevention of complications. We analyzed the time taken from HBV DNA loss to viral breakthrough after antiviral treatment in patients with chronic hepatitis B (CHB). The early fall of the HBV DNA level to undetectable levels assessed really whether it is related to late breakthrough. Methods: A total of 91 patients whose HBV DNA levels dropped below undetectable levels were chosen from lamivudine-treated 306 patients and were analyzed retrospectively. The patients were divided into 4 groups (A≤12, 12<B≤24, 24<C≤48, D>48 wk) according to the time taken for the HBV DNA to decrease below undetectable levels. HBV DNA level was determined every 3 months. Results: The mean time taken for loss of HBV DNA was 34±28 wk. The baseline ALT differed significantly among groups (A: 382±274, B: 340±30, C: 166±92, D: 54±100 IU/L) (p=0.007). Fifty nine of the 91 patients (64.8%) experienced viral breakthrough. The mean interval between HBV DNA loss and viral breakthrough was 65±40 wk and differed significantly between group A, B (82±43 wk) and group C, D (56±28 wk) (p=0.015). In multivariate analysis, only HBV DNA loss within 24 wk, was found to be independently associated with late viral breakthrough (p=0.035). Undetectable HBV DNA after 24 wk was associated with high odd ratio of 3.24 (95% CI, 1.09-9.67). Conclusions: HBV DNA loss within 24 wk after antiviral treatment could predict the late breakthrough. (Korean J Gastroenterol 2011;58:25-30)