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Seasonal Dynamics of Nutrient Loading and Chlorophyll A in a Northern Prairies Reservoir, Saskatchewan, Canada

Journal of Water Resource and Protection 2012年第4期4卷 180-202页

作者： Markus Hecker Jong Seong Khim John P. Giesy Su-Qing Li joo-hyung ryu Division of Environmental Science and Ecological Engineering Korea University Seoul Korea Korea Ocean Satellite Centre Korea Ocean R&D Institute Ansan Korea School of the Environment & Sustainability University of Saskatchewan Saskatoon Canada Toxicology Centre University of Saskatchewan Saskatoon Canada

Harmful algae blooms have become an increasing concern in context with the safety of water resources around the globe;however, little is known about the dynamics and specific causes of such blooms in the prairie ecozone in North America. The aim of this study was to research the nitrogen (N) and phosphorous (P) content and nutrient limitation (defined as N and P limitation) of growth of cyanobacteria in a northern prairies reservoir (Lake Diefenbaker [LD], SK, Canada). A combination of concentration balance analysis for N and P, controlled bioassays with the natural consortium of phytoplankton or defined monocultures of cyanobacteria, and satellite imagery was applied to address this aim. The current trophic status of Lake Diefenbaker is one of moderate eutrophication. Primary production in the lake is P-limited, and N did not represent a limiting factor for algal production. There was no significant increase in TP con- centrations between the upper and lower portions of the reservoir, indicating that most of the phosphorus in LD comes from upstream sites in Alberta. Anabaena circinalis, a species that has the potential to seriously degrade lake ecosys- tems, was identified as the predominant cyanobacteria in LD. Together with the fact that TP influxes into the reservoir primarily originate from upstream sources, these results suggest the need for remedial measures in the upstream reach of the South Saskatchewan River. Satellite imaging represented a promising approach in support of monitoring for po- tential algal blooms in LD;however, due to limited sensitivity and issues associated with atmosphere interference this methodology should only be used in combination with in situ water quality monitoring. In summary, while this study indicated that Lake Diefenbaker is potentially at risk with cyanobacteria blooms (some of which such as Anabena sp. that can produce toxins) during late summer and fall, development of clear causal relationships and risk assessment strateg

关键词： Cyanobacteria Eutrophication Prairie Ecozone Satellite Imaging Phophorous Nitrogen Monitoring

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Superior mechanical properties and strengthening mechanisms of lightweight AlxCrNbVMo refractory high-entropy alloys(x=0,0.5,1.0)fabricated by the powder metallurgy process

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Journal of Materials Science & Technology 2021年第10期69卷 32-41页

作者： Byungchul Kang Taeyeong Kong Ho Jin ryu Soon hyung Hong Department of Material Science and Engineering Korea Advanced Institute of Science and Technology(KAIST)291 Daehak-roYuseong-guDaejeon 34141Republic of Korea Department of Nuclear and Quantum Engineering Korea Advanced Institute of Science and Technology(KAIST)291 Daehak-roYuseong-guDaejeon 34141Republic of Korea

Light and strong AlxCrNbVMo(x=0,0.5,and 1.0)refractory high-entropy alloys(RHEAs)were designed and fabricated via a the powder metallurgical *** microstructure of the AlxCrNbVMo alloys consisted of a single BCC crystalline structure with a sub-micron grain size of 2-3μm,and small amounts(<4 vol.%)of fine oxide *** homogeneous microstructure,without chemical segregation or micropores was achieved via high-energy ball milling and spark-plasma *** alloys exhibited superior mechanical properties at 25 and 1000℃compared to those of other ***,CrNbVMo alloy showed a yield strength of 2743 MPa at room ***,the yield strength of the CrNbVMo alloy at 1000℃was 1513 *** specific yield strength of the CrNbVMo alloy was increased by 27%and 87%at 25 and 1000℃,respectively,compared to the AlMo_(0.5) NbTa_(0.5)TiZr RHEA,which exhibited so far the highest specific yield strength among the cast *** addition of Al to CrNbVMo alloy was advantageous in reducing its reduce density to below 8.0 g/cm^(3),while the elastic modulus decreased due to the much lower elastic modulus of Al compared to that of the CrNbVMo *** analysis of the strengthening contributions,showed that the solid solution strengthening,arising from a large misfit effect due to the size and modulus,and the high shear modulus of matrix,was revealed to predominant strengthening mechanism,accounting for over 50%of the yield strength of the AlxCrNbVMo RHEAs.

关键词： High-entropy alloy Powder metallurgy Refractory Strengthening mechanisms Oxide dispersoids

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Flapping dynamics of a flexible propulsor near ground

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Acta Mechanica Sinica 2016年第6期32卷 991-1000页

作者： Jaeha ryu Sung Goon Park Boyoung Kim hyung Jin Sung Department of Mechanical Engineering Korea Advanced Institute of Science and Technology

The flapping motion of a flexible propulsor near the ground was simulated using the immersed boundary method. The hydrodynamic benefits of the propulsor near the ground were explored by varying the heaving frequency (St) of the leading edge of the flexible propulsor. Propulsion near the ground had some advantages in generating thrust and propelling faster than propulsion away from the ground. The mode analysis and flapping amplitude along the Lagrangian coordinate were examined to analyze the kinematics as a function of the ground proximity (d) and St. The trailing edge amplitude (\(a_\mathrm{tail}\)) and the net thrust (\(\overline{{F}}_x\)) were influenced by St of the flexible propulsor. The vortical structures in the wake were analyzed for different flapping conditions.

关键词： Flexible propulsor Ground effect Immersed boundary method Mode analysis

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First-Order System Least-Squares Methods for a Flux Control Problem by the Stokes Flow

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Communications in Computational Physics 2010年第4期7卷 738-758页

作者： Soorok ryu Sang Dong Kim hyung-Chun Lee Department of Industrial and Applied Mathematics Kyungpook National UniversityDaegu 702-701Korea Department of Mathematics Kyungpook National UniversityDaegu 702-701Korea Department of Mathematics Ajou UniversitySuwon 443-749Korea

This article deals with a first-order least-squares approach to the solution of an optimal control problem governed by Stokes *** with our earlier work on a velocity control by the Stokes flow in[***,H.-*** and ***,SIAM ***.,47(2009),pp.1524-1545],we recast the objective functional as a H1 seminorm in the velocity control *** introducing a velocity-flux variable and using the Lagrange multiplier rule,a first-order optimality system is *** show that the least-squares principle based on L2 norms applied to this system yields the optimal discretization error estimates for each variable in H1 norm,including the velocity *** numerical tests,multigrid method is employed to the discrete algebraic system,so that the velocity and flux controls are obtained.

关键词： Optimal control optimization least-squares finite element methods Lagrange multiplier Stokes equations.

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Stone extraction balloon-guided repeat self-expanding metal stent placement

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World Journal of Gastroenterology 2010年第24期16卷 3087-3090页

作者： hyung Hun Kim Jeong Seop Moon Soo hyung ryu Jung Hwan Lee You Sun Kim Division of Gastroenterology Department of Internal MedicineSeoul Paik Hospital Inje University College of Medicine

Self-expanding metal stent (SEMS) placement offers safe and effective palliation in patients with upper gastrointestinal obstruction due to a malignancy. Well described complications of SEMS placement include tumor growth, obstruction, and stent migration. SEMS occlusions are treated by SEMS redeployment, argon plasma coagulation application, balloon dilation, and surgical bypass. At our center, we usually place the second SEMS into the first SEMS if there is complete occlusion by the tumor. We discovered an unusual complication during SEMS redeployment. The guide-wire passed through the mesh of the first SEMS and caused the second SEMS to become entangled with the first SEMS. This led to the distortion and malfunction of the second SEMS, which worsened the gastric outlet obstruction. For lowering the risk of entanglement, we studied stone extraction balloon-guided repeat SEMS placement. This is the first report of a SEMS entangled by the mesh of the first SEMS and stone extraction balloon-guided repeat SEMS placement for lowering the risk of this complication.

关键词： Gastric outlet obstruction Self-expanding metal stent

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Counter-balancing effects of Si on C partitioning and stacking fault energy of austenite in 10Mn quenching and partitioning steel

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Journal of Materials Science & Technology 2022年第3期98卷 248-257页

作者： Dong Hwi Kim Jee-Hyun Kang Hojun Gwon joo Hyun ryu Sung-joon Kim Graduate Institute for Ferrous Technology Pohang University of Science and TechnologyPohang 37673Republic of Korea School of Materials Science and Engineering Institute of Materials TechnologyYeungnam UniversityGyeongsan 38541Republic of Korea POSCO Technical Research Laboratories POSCOGwangyang 57807Republic of Korea

Silicon is an essential alloying element in quenching and partitioning(Q&P)steels,because it is known to suppress carbide precipitation during partitioning step and promote carbon partitioning to stabilize *** 2 wt%Si was added to 10Mn-2Al-0.2C steel,the size and fraction of the carbides formed during partitioning became smaller than in the Si-free ***,the suppression of carbide formation promoted C partitioning into austenite as ***,austenite stability was always lower with Si under the equivalent partitioning condition because Si effectively decreased the stacking fault energy of *** partitioning progressed,the both yield and tensile strengths of the Si-added steel exceeded that of the Si-free steel with the similar ductility *** was because Si was an effective solid solution strengthener,and the austenite in the Si-added steel exhibited the appropriate stability to gradually transform into martensite throughout the *** resulting strengthening effect compensated for the softening caused by martensite ***,strain hardening rate decreased continuously throughout deformation,which resulted in high tensile strength and ductility.

关键词： Steels Q&P steel Silicon Austenite stability Tensile deformation Stacking fault energy Medium Mn steel

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Genomic change in hepatitis B virus associated with development of hepatocellular carcinoma

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World Journal of Gastroenterology 2016年第23期22卷 5393-5399页

作者： Danbi Lee Heather Lyu Young-Hwa Chung Jeong A Kim Priya Mathews Elizabeth Jaffee Lei Zheng Eunsil Yu Young joo Lee Soo hyung ryu Department of Internal Medicine University of Ulsan College of MedicineAsan Medical Center Sidney Kimmel Comprehensive Cancer Center Johns Hopkins University School of MedicineBaltimore Department of Pathology University of Ulsan College of MedicineAsan Medical Center Department of Hepatobiliary Surgery University of Ulsan College of MedicineAsan Medical Center Department of Internal Medicine Inje Uni-versity College of MedicineSeoul Paik Hospital

AIM: To determine the genomic changes in hepatitis B virus(HBV) and evaluate their role in the development of hepatocellular carcinoma(HCC) in patients chronically infected with genotype C ***: Two hundred and forty chronic hepatitis B(CHB) patients were subjected and followed for a median of 105 mo. HCC was diagnosed in accordance with AASLD guidelines. The whole X, S, basal core promoter(BCP), and precore regions of HBV were sequenced using the direct sequencing ***: All of the subjects were infected with genotype C HBV. Out of 240 CHB patients, 25(10%) had C1653 T and 33(14%) had T1753 V mutation in X region; 157(65%) had A1762T/G1764 A mutations in BCP region, 50(21%) had G1896 A mutation in precore region and 67(28%) had pre-S deletions. HCC occurred in 6 patients(3%). The prevalence of T1753 V mutation was significantly higher in patients who developed HCC than in those without HCC. The cumulative occurrence rates of HCC were 5% and 19% at 10 and 15 years, respectively, in patients with T1753 V mutant, which were significantly higher than 1% and 1% in those with wild type HBV(P < 0.001).CONCLUSION: The presence of T1753 V mutation in HBV X-gene significantly increases the risk of HCC development in patients chronically infected with genotype C HBV.

关键词： Hepatocellular carcinoma Chronic hepatitis B Genomic change Hepatitis B virus Genotype C

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Improving Application Launch Performance on Solid State Drives

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Journal of Computer Science & Technology 2012年第4期27卷 727-743页

作者： Yongsoo joo Junhee ryu Sangsoo Park Kang G.Shin Department of Computer Science and Engineering Ewha Womans University IEEE Department of Computer Science and Engineering Seoul National University Department of Electrical Engineering and Computer Science University of Michigan

Application launch performance is of great importance to system platform developers and vendors as it greatly affects the degree of users＇ satisfaction. The single most effective way to improve application launch performance is to replace a hard disk drive （HDD） with a solid state drive （SSD）, which has recently become affordable and popular. A natural question is then whether or not to replace the traditional HDD-aware application launchers with a new SSD-aware optimizer. We address this question by analyzing the inefficiency of the HDD-aware application launchers on SSDs and then proposing a new SSD-aware application prefetching scheme, called the Fast Application STarter （FAST）. The key idea of FAST is to overlap the computation （CPU） time with the SSD access （I/O） time during an application launch. FAST is composed of a set of user-level components and system debugging tools provided by Linux OS （operating system）. Hence, FAST can be easily deployed in any recent Linux versions without kernel recompilation. We implement FAST on a desktop PC with an SSD running Linux 2.6.32 OS and evaluate it by launching a set of widely-used applications, demonstrating an average of 28% reduction of application launch time as compared to PC without a prefetcher.

关键词： application launch performance I/O prefetch solid state drive

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In-situ synthesis of TiC/Fe alloy composites with high strength and hardness by reactive sintering

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Journal of Materials Science & Technology 2018年第8期34卷 1397-1404页

作者： Junho Lee Dongju Lee Myung Hoon Song Wonhyuk Rhee Ho Jin ryu Soon hyung Hong Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology291 Daehak-roYuseong-guDaejeon305-701Republic of Korea Department of Nuclear and Quantum Engineering Korea Advanced Institute of Science and Technology291 Daehak-roYuseong-guDaejeon305-701Republic of Korea Nuclear Materials Development Division Korea Atomic Energy Research Institute111 Daedeok-daero 989 Beon-gilYuseong-guDaejeon305-353Republic of Korea Daewha Alloytech Corporation 17-60Sanupdanji-gilMyeoncheon-myeonDangjin-siChungcheongnam-doRepublic of Korea

Fe alloy composites reinforced with in-situ titanium carbide （TIC） particles were fabricated by reactive sintering using different reactant C/Ti ratios of 0.8, 0.9, 1 and 1.1 to investigate the microstructure and mechanical properties ofin-situ TiC/Fe alloy composites. The microstructure showed that the in-situ syn- thesized TiC particles were spherical with a size of 1-3 }~m, irrespective of C/Ti ratio. The stoichiometry of in-situ TiC increased from 0.85 to 0.88 with increasing C/Ti ratio from 0.8 to 0.9, but remained almost unchanged for C/Ti ratios between 0.9 and 1.1 due to the same driving force for carbon diffusion in TiCx at the common sintering temperature. The in-situ TiC/Fe alloy composite with C[Ti ~ 0.9 showed improved mechanical properties compared with other C/Ti ratios because the presence of excess carbon （C/Ti = 1 and 1.1） resulted in unreacted carbon within the Fe alloy matrix, while insufficient carbon （C/Ti = 0.8） caused the depletion of carbon from the Fe alloy matrix, leading to a significant decrease in hardness. This study presents that the maximized hardness and superior strength of in-situ TiC/Fe alloy composites can be achieved by microstructure control and stoichiometric analysis of the in-situ synthesized TiC par- ticles, while maintaining the ductility of the composites, compared to those of the unreinforced Fe alloy. Therefore, we anticipate that the in-situ synthesized TiC/Fe alloy composites with enhanced mechanical properties have great potential in cutting tool, mold and roller material applications.

关键词： Metal matrix composites Sintering Mechanical properties Microstructures

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Parameter selection of pocket extraction algorithm using interaction interface

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第9期7卷 1492-1499页

作者： KIM Chong-Min WON Chung-In ryu joonghyun CHO Cheol-hyung BHAK Jonghwa KIM Deok-Soo Department of Industrial Engineering Hanyang University Seoul 133-791 Korea Voronoi Diagram Research Center Hanyang University Seoul 133-791 Korea Samsung Electronics Suwon Gyeonggi-do 443-742 Korea Korean Bioinformation Center Korea Research Institute of Bioscience and Biotechnology Daejeon 305-806 Korea Department of Industrial Engineering Hanyang University Seoul 133-791 Korea)

Pockets in proteins have been known to be very important for the life process. There have been several studies in the past to automatically extract the pockets from the structure information of known proteins. However, it is difficult to find a study comparing the precision of the extracted pockets from known pockets on the protein. In this paper, we propose an algorithm for extracting pockets from structure data of proteins and analyze the quality of the algorithm by comparing the extracted pockets with some known pockets. These results in this paper can be used to set the parameter values of the pocket extraction algorithm for getting better results.

关键词： Pocket Protein Interaction interface Protein interaction Voronoi diagram

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