Growth and Characterization of BeO Thin Films Grown by Atomic Layer Deposition Using H₂O and O₃ as Oxygen Sources

Lee, Woo Chul,Cho, Cheol Jin,Kim, Sangtae,Larsen, Eric S.,Yum, Jung Hwan,Bielawski, Christopher W.,Hwang, Cheol Seong,Kim, Seong Keun American Chemical Society 2017 The Journal of Physical Chemistry Part C Vol.121 No.32

<P>Growth characteristics and properties of BeO films grown by atomic layer deposition (ALD) are investigated. ALD chemistries between dimethylberyllium and two different oxygen sources, H2O and O-3, are governed by different reaction mechanisms, resulting in different film properties. At growth temperatures ranging from 150 to 300 degrees C, the properties of the BeO films grown using H2O are temperature-independent. In contrast, the BeO films grown using O-3 at low temperatures (<200 degrees C) show high concentrations of carbon and hydrogen, possibly owing to the incomplete removal of the ligands of the precursor, leading to a low film density. This correlates with the evolution of the rough surface and the microstructure composed of few nanometer-sized grains. The low-quality BeO films grown using O-3 at low temperatures (<200 degrees C) show a decreased band gap (E-g: 7.77.9 eV) and dielectric constant (epsilon(r): 5.66.7). Above 250 degrees C, these properties recovered to the levels (E-g similar to 9.4 eV and epsilon(r) similar to 8.1) of the BeO films grown using H2O, which show high values of E-g similar to 9.19.4 eV and epsilon(r) similar to 8. Collectively, these findings demonstrate that the O-3-ALD process requires relatively more thermal energy than H2O-ALD does, to produce high-quality BeO films.</P>

1Cr1Mo1/4V 터빈 로터강의 크리프 손상 모델에 관한 연구

최우성(Woo Sung Choi),에릭플러리(Eric Fleury),송기욱(Gee Wook Song),김범신(Bum Shin Kim),장성호(Sung Ho Chang) 대한기계학회 2011 大韓機械學會論文集A Vol.35 No.4

일반적으로 화력발전 터빈 로터나 케이싱과 같이 고온 고압에서 운전되는 설비의 경우 크리프 및 피로 손상이 주된 손상기구로 알려져 있다. 터빈 설비의 수명을 정확하게 예측하기 위해서 크리프 및 피로 손상 기구를 복합적으로 고려해야 하지만 500MW 급 대용량 터빈 설비의 경우 기저 부하를 담당하기 때문에 기동횟수가 많지 않고 고온에서 장시간 동안 안정적인 운전을 하므로 잔여수명을 결정할 때 크리프 수명을 주로 사용한다. 국내에서 20 년 넘게 운전되고 있는 대용량 터빈의 경우 대부분 니켈, 크롬, 몰리브덴, 바나듐 성분이 포함한 재료로 되어 있다. 본 논문에서는 대용량 터빈의 크리프 수명을 예측하기 위하여 1Cr1Mo1/4V 터빈 로터강에 대한 크리프 손상 모델을 제안하고자 한다. It is well known that the dominant damage mechanisms in high-temperature steam turbine facilities such as rotor and casing are creep and fatigue damages. Even though coupling of creep and fatigue should be considered while predicting the life of turbine facilities, the remaining life of large steam turbine facilities is generally determined on the basis of creep damage because the turbines must generate stable base-load power and because they are operated at a high temperature and pressure for a long time. Almost every large steam turbine in Korea has been operated for more than 20 years and is made of steel containing various amounts of principal alloying elements nickel, chromium, molybdenum, and vanadium. In this study, creep damage model of 1Cr1Mo1/4V steel for turbine rotor is proposed and that can assess the high temperature creep life of large steam turbine facilities is proposed.

Noninvasive Tests of Fibrosis as Markers of Disease Progression in Patients with Non-Alcoholic Steatohepatitis (NASH)

( Jin-woo Lee ),( George Boon Bee Goh ),( Quentin M. Anstee ),( Mi-chael Trauner ),( Eric J. Lawitz ),( Natalie Bzowej ),( Raj Vuppalan-chi ),( Ziad Younes ),( Dora Ding ),( Georgia Li ),( Kathryn Ker 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1

Aims: Surrogate endpoints that predict complications are necessary for approval of new therapies for NASH. We assessed associations between histologic and noninvasive fibrosis markers with disease progression in NASH. Methods: Patients with advanced fibrosis (Ishak stages 3-6) due to NASH (NAS ≥3) were enrolled in Phase 3, placebo-controlled trials of selonsertib. Treatment groups were combined for this analysis. Liver fibrosis at baseline[BL] and W48 were staged according to the Ishak classification. Hepatic collagen and a-SMA expression were quantified by morphometry. Noninvasive tests of fibrosis such as LS by TE, ELF and NAFLD Fibrosis Score (NFS) were calculated. Cox regression determined associations between these parameters with disease progression (i.e. progression to cirrhosis in patients with bridging fibrosis and adjudicated clinical events [e.g. decompensation, transplantation, death] in those with cirrhosis), and discrimination was assessed using c-statistics. Results: 1679 subjects with bridging fibrosis(n=802) or cirrhosis( n=877) were randomized (median age 59 yrs, 60% female, 74% diabetes). During a median follow-up(FU) of 14.3 mos, 16% of subjects (117/748 with W48 biopsies) with bridging fibrosis progressed to cirrhosis. Risk of histological progression was greater with higher BL Ishak stage, hepatic collagen, a-SMA expression, ELF, NFS, and LS, as well as greater increases in these markers over time(Table). BL ELF(c-statistic, 0.68) and LS(0.70) more accurately discriminated progression to cirrhosis than BL Ishak stage(0.58) and hepatic collagen(0.56; all P<0.05). During a median FU of 14.3 mos, 26(3%) cirrhotic subjects had clinical events. BL factors associated with clinical events included higher Ishak stage, hepatic collagen, a-SMA, ELF, NFS, and LS(Table). After adjustment for BL, increases in hepatic collagen, a-SMA, NFS, and LS were associated with an increased risk of events. Prediction of future clinical events was greatest for BL ELF (c-statistic, 0.84 vs. 0.66 for Ishak stage and 0.62 for hepatic collagen; both P<0.05). Conclusions: Clinical disease progression in patients with advanced fibrosis due to NASH is associated with greater fibrosis burden at baseline and larger increases over time, measured histologically or with noninvasive markers. These data support the utility of noninvasive fibrosis markers as endpoints in NASH clinical trials.

1Cr1Mo1/4V 터빈 로터강의 크리프 손상 모델에 관한 연구

최우성(Woo Sung Choi),에릭플러리(Eric Fleury),송기욱(Gee Wook Song),김범신(Bum Shin Kim) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

일반적으로 화력발전 터빈 로터나 케이싱과 같이 고온 고압에서 운전되는 설비의 경우 크리프 및 피로 손상이 주된 손상기구로 알려져 있다. 터빈 설비의 수명을 정확하게 예측하기 위해서 크리프 및 피로 손상 기구를 복합적으로 고려해야 하지만 500㎿ 급 대용량 터빈 설비의 경우 기저 부하를 담당하기 때문에 기동횟수가 많지 않고 고온에서 장시간동안 안정적인 운전을 하므로 잔여수명을 결정할 때 크리프 수명을 주요 사용한다. 20년 넘게 운전되고 있는 한국의 대용량 터빈의 경우 대부분 니켈, 크롬, 몰리브덴, 바냐듐 성분이 포함한 재료로 되어 있다. 본 논문에서는 대용량 터빈의 크리프 수명을 예측하기 위한 1Cr1Mo1/4V 터빈 로터강에 대한 크리프 손상 모델을 제안하고자 한다. It is well known that dominant damage mechanisms of high temperature steam turbine facilities such as rotor and casing are creep and fatigue damages. Even though coupling of creep and fatigue should be considered in the life prediction of turbine facilities, a remaining life of large steam turbine facilities is generally determined by creep damage. Because those turbines must provide stable base-load power and are operated under high temperature and high pressure for a long time. Almost large steam turbine of Korea, operated over 20 years, made of steels containing various amounts of principal alloying elements nickel, chromium, molybdenum and vanadium. In this paper, creep damage model of 1Cr1Mo1/4V turbine rotor steels is proposed to assess the high temperature creep life of large steam turbine facilities.

Effects of Nintedanib on Markers of Epithelial Damage in Subjects with IPF: Data from the INMARK Trial

( Jin Woo Song ),( R Gisli Jenkins ),( Imre Noth ),( Moisés Selman ),( Vincent Cottin ),( Yasuhiko Nishioka ),( Antje Prasse ),( Eric S White ),( Carina Ittrich ),( Claudia Diefenbach ),( Klaus B Rohr 대한결핵 및 호흡기학회 2020 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.128 No.-

Background The INMARK trial investigated effects of nintedanib on blood biomarkers in subjects with IPF. We investigated the effect of nintedanib on markers of epithelial damage. Methods Subjects (n=346) with IPF and FVC ≥80% predicted were randomised 1:2 to receive nintedanib 150 mg bid or placebo double-blind for 12 weeks, followed by open-label nintedanib for 40 weeks. Blood samples were taken at weeks 4, 8, 12, 16, 20, 24, 36, and 52. We assessed the rate of change (slope) in log10-transformed CA-125 and CA19-9 (two markers of epithelial damage) from baseline to week 12 using random coefficient regression and changes in log10-transformed CA-125 and CA19-9 over 52 weeks using a mixed model for repeated measures. Results The adjusted rate of change in CA-125 levels from baseline to week 12 was significantly different for nintedanib vs placebo (difference -0.046 U/mL/month [95% CI 0.056, -0.035]; p<0.001). Adjusted mean CA-125 levels decreased with nintedanib vs placebo from week 4; after week 12 CA-125 levels were similar between groups (Figure). There was no significant difference between nintedanib and placebo in the adjusted rate of change in CA19-9 levels from baseline to week 12 (difference -0.023 U/mL/month [95% CI -0.055, 0.009]; p=0.17). Adjusted mean CA19-9 levels over 52 weeks were similar in both groups. Conclusion CA-125 may be a biomarker of response to nintedanib in patients with IPF.

Gene Expression Profiling in Patients with Idiopathic Pulmonary Fibrosis (IPF) in the INMARK Trial

( Jin Woo Song ),( Moisés Selman ),( R Gisli Jenkins ),( Eric S White ),( Vincent Cottin ),( Yasuhiko Nishioka ),( Imre Noth ),( Antje Prasse ),( Benjamin Strobel ),( German Leparc ),( Carina Ittrich 대한결핵 및 호흡기학회 2020 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.128 No.-

Background The INMARK trial investigated blood biomarkers as predictors of disease progression in patients with IPF and preserved lung function. In this study, we investigated changes in gene expression levels in patients treated with nintedanib and placebo. Methods Subjects with IPF and FVC ≥80% predicted were randomized 1:2 to receive nintedanib or placebo for 12 weeks followed by open-label nintedanib for 40 weeks. Total RNA was extracted from whole blood samples taken at baseline and week 12. Changes in gene expression levels from baseline to week 12 were analyzed. Data were log2 transformed prior to analysis. Changes in gene expression levels were considered significant if p≤0.05 and |log2fold change|≥0.5. Results Of 116 and 230 subjects randomized to receive nintedanib and placebo, respectively, data from 110 and 217 patients were included in the analysis. Of 60,675 genes evaluated, 14,799 had counts per million ≥1 in at least half the samples from either treatment group per time point and were included in the analysis. In adjusted analyses, compared with baseline levels, no genes were downregulated after 12 weeks’ treatment with placebo, while nine genes were downregulated after 12 weeks’ treatment with nintedanib (Table). No genes were upregulated. In unadjusted analyses, the change from baseline in expression level at week 12 was significantly different between nintedanib and placebo for five genes (SHISA4, LTF, CTSG, OLFM4, DEFA4) (Table). Pathways analysis suggested that the genes downregulated in patients treated with nintedanib were related to neutrophil function and extracellular matrix organization. Conclusions These analyses of the INMARK trial, based on genome-wide transcriptome profiling, identified a small number of genes that were downregulated after 12 weeks of nintedanib treatment in subjects with IPF and preserved lung function. The potential of gene expression profiling as a marker of treatment response in patients with IPF requires further study.

A Life Assessment for Steam Turbine Rotor Subjected to Thermo-Mechanical Loading Using Inelastic Analysis

Choi, Woo Sung,Fleury, Eric,Song, Gee Wook,Hyun, Jung Seob Trans Tech Publications, Ltd. 2006 Key engineering materials Vol.326 No.-

<P>An important characteristic of a steam power plant is its ability to maintain reliability and safety of the plant against frequent start-ups and load changes. Transient regimes arising during start-ups, shut-downs and load changes give rise to unsteady temperature distribution with time in steam turbine rotor(HP/IP), which results in non-uniform strain and stress distribution. The rapid increase of temperature and rotational speed during starts-ups, especially, makes conditions more severe and causes main components’ damage and reduction of life span for steam turbine. Thus accurate knowledge of thermal and centrifugal stresses are required for the integrity and lifetime assessment for the turbine rotor. So far, only elastic calculations are currently performed for simplicity. However, it is well known that the materials of steam turbine rotor deform inelastically at high temperature. Existing models proposed to describe the viscoplastic(rate-dependent) behavior are rather elaborate and difficult to incorporate with computer simulations in the case of complex structures. In this paper, the life assessment for steam turbine rotor was established by combining the inelastic behavior and the finite element method. The inelastic analysis was particularly focused on viscoplastic behavior that is simple enough to be used effectively in computer simulation and matches the essential features of the time-dependent inelastic behavior of materials reasonably well for cyclic loading under non-isothermal conditions. Using this study, life consumption of steam turbine rotor can be obtained.</P>

Crystallization-induced plasticity of Cu–Zr containing bulk amorphous alloys

Lee, Seok-Woo,Huh, Moo-Young,Fleury, Eric,Lee, Jae-Chul Elsevier 2006 ACTA MATERIALIA Vol.54 No.2

<P><B>Abstract</B></P><P>This study examined the parameter governing the plasticity observed in various Cu–Zr containing monolithic amorphous alloys. All the alloys were fully amorphous in their as-cast condition but exhibited different plastic strains. Microscopic observations of the quasi-statically compressed alloys showed abundant nanocrystallites in the amorphous matrices in the alloys that exhibited pronounced plasticity. On the other hand, insignificant changes in the microstructure were observed in the alloy that did not show plasticity. The mechanism for the formation of these deformation-induced nanocrystallites was examined from the viewpoints of thermodynamics and kinetics. The role of the deformation-induced nanocrystallites on the plasticity of the amorphous alloy was examined using high-resolution transmission electron microscopy. The results demonstrate that compressive loading facilitates nanocrystallization in monolithic Cu–Zr containing amorphous alloys, resulting in plasticity. The parameter governing the plasticity in these monolithic Cu–Zr containing amorphous alloys lies in the activation energy for the overall crystallization process.</P>

Brain Tumor Classification by Methylation Profile

Park Jin Woo,Lee Kwanghoon,Kim Eric Eunshik,Kim Seong-Ik,Park Sung-Hye 대한의학회 2023 Journal of Korean medical science Vol.38 No.43

The goal of the methylation classifier in brain tumor classification is to accurately classify tumors based on their methylation profiles. Accurate brain tumor diagnosis is the first step for healthcare professionals to predict tumor prognosis and establish personalized treatment plans for patients. The methylation classifier can be used to perform classification on tumor samples with diagnostic difficulties due to ambiguous histology or mismatch between histopathology and molecular signatures, i.e., not otherwise specified (NOS) cases or not elsewhere classified (NEC) cases, aiding in pathological decision-making. Here, the authors elucidate upon the application of a methylation classifier as a tool to mitigate the inherent complexities associated with the pathological evaluation of brain tumors, even when pathologists are experts in histopathological diagnosis and have access to enough molecular genetic information. Also, it should be emphasized that methylome cannot classify all types of brain tumors, and it often produces erroneous matches even with high matching scores, so, excessive trust is prohibited. The primary issue is the considerable difficulty in obtaining reference data regarding the methylation profile of each type of brain tumor. This challenge is further amplified when dealing with recently identified novel types or subtypes of brain tumors, as such data are not readily accessible through open databases or authors of publications. An additional obstacle arises from the fact that methylation classifiers are primarily research-based, leading to the unavailability of charging patients. It is important to note that the application of methylation classifiers may require specialized laboratory techniques and expertise in DNA methylation analysis.

Functionally Graded Bismuth Oxide/Zirconia Bilayer Electrolytes for High-Performance Intermediate-Temperature Solid Oxide Fuel Cells (IT-SOFCs)

Joh, Dong Woo,Park, Jeong Hwa,Kim, Doyeub,Wachsman, Eric D.,Lee, Kang Taek American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.10

<P>A functionally graded Bi1.6.Er0.4O3(ESB)/Y0.16Zr0.84O1.92(YSZ) bilayer electrolyte is successfully developed via a cost-effective screen printing process using nanoscale ESB powders on the tape-cast NiO-YSZ anode support. Because of the highly enhanced oxygen incorporation process at the cathode/electrolyte interface, a novel bilayer solid oxide fuel cell (SOFC) yields extremely high power density of similar to 2.1 W cm(-2) at 700 degrees C, which is a 2.4 times increase compared to that of the YSZ single electrolyte SOFC.</P>