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EXPERIMENTAL ESTIMATION OF A SCALING EXPONENT FOR TIP VORTEX CAVITATION VIA ITS INCEPTION TEST IN FULL-AND MODEL-SHIP

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Journal of Hydrodynamics 2012年第5期24卷 658-667页

作者： lee Jeung-Hoon JUNG Jae-Kwon lee Kyung-Jun HAN Jae-moon PARK Hyung-Gil SEO Jong-soo Samsung Ship Model Basin(SSMB) Marine Research InstituteSamsung Heavy IndustriesScience TownDaejeon 305-380Korea

Tip vortex cavitation noise of marine propeller became primary concems to reduce hazardous environmental impacts from commercial ship or to keep the underwater surveillance of naval ships. The investigations of the tip vortex and its induced noise are normally conducted through the model test in a water cavitation tunnel. However the Reynolds number of model-test is much smaller than that of the full-scale, which subsequently results in the difference of tip vortex cavitation inception. Hence, the scaling law between model- and full-scales needs to be identified prior to the prediction and assessment of propeller noise in full scale. From previous researches, it is generally known that the incipient caivtation number of tip vortex can be represented as a power of the Reynolds number. However, the power exponent for scaling, which is the main focus of this research, has not been clearly studied yet. This paper deals with the estimation of scaling exponent based on tip vortex cavitation inception test in both full- and model-scale ships. Acoustical measurements as well as several kind of signal processing technique for an inception criterion suggest the scaling exponent as 0.30. The scaling value proposed in this study shows slight difference to the one of most recent research. Besides, extrapolation of model-ship noise measurement using the proposed one predicts the full-scale noise measurement with an acceptable discrepancy.

关键词： tip vortex cavitation underwater radiated noise scaling exponent

Significance of age and comorbidity as prognostic indicators for patients with bladder cancer

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Asian Journal of Andrology 2010年第5期12卷 766-774页

作者： moon soo Ha In Ho Chang Department of Urology College of Medicine Chung-Ang University Seou1140-75 7 Korea

The aim of this study was to determine the impact that age and comorbidity status have on both overall and bladder cancer-specific survival of bladder cancer patients. We obtained medical information pertaining to a population of 528 patients with newly diagnosed bladder cancer from Chung-Ang University Hospital cancer registry. The Adult Comorbidity Evaluation-27 （ACE-27） test, which has been previously validated in adult cancer patients, was used to assess comorbidity. We evaluated differences in the demographic and clinical characteristics of included patients, as well as differences in the treatments they received after categorizing them by age. The median age at the time of bladder cancer diagnosis of the entire cohort was 63 years, and the median follow-up time was 97 months. Of the 528 patients who were included in our study, 303 had at least one comorbid condition and 249 died during the follow-up period. When patients were stratified by age, we found that older patients had a higher proportion of severe comorbidities （P 〈 0.01） than younger patients, and that a lower proportion of them underwent radical cystec- tomy for invasive bladder cancer （IBC）（P 〈 0.01）. By multivariate analysis, we found that older age was predictive of lower overall survival （OS） and bladder cancer-specific survival （BCSS） rates among patients with superficial bladder cancer （SBC） and of lower OS rates among patients with IBC. We also found that moderate-severe comorbidity status and treatment through a bladder-conserving approach were predictive of lower OS and cancer-specific survival rates among patients with IBC. The disparity between overall deaths and bladder cancer deaths was shown in SBC and increased along with age and higher comorbidity. Age and comorbidity were found to be independent predictive factors of OS and BCSS among bladder cancer patients, and explained the disparity that we observed between overall bladder cancer-specific mortality rates.

关键词： age comorbidity neoplasm prognostic indicator urinary bladder

Optimistic performance of carbon-free hydrazine fuel cells based on controlled electrode structure and water management

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Journal of Energy Chemistry 2020年第12期29卷 175-181页

作者： Hongsun Hwang Sujik Hong Do-Hyeong Kim moon-Sung Kang Jin-soo Park Sunghyun Uhm Jaeyoung lee Electrochemical Reaction and Technology Laboratory(ERTL) School of Earth Sciences and Environmental EngineeringGwangju Institute of Science and Technology(GIST)Cwangju 61005Republic of Korea Ertl Center for Electrochemistry and Catalysis Gwangju Institute of Science and Technology(GIST)Gwangju 61005Republic of Korea Department of Green Chemical Engineering Sangmyung UniversityCheonanChungnam 31066Republic of Korea Plant Engineering Center Institute for Advanced EngineeringYongin 17180Republic of Korea

In this study, we first attempted to discover the optimal configuration of membrane-electrode assemblies(MEAs) used to achieve a high performance of direct hydrazine fuel cells(DHFCs). We have investigated the effect of water management and the electrode thickness on the performance of DHFCs, depending on the hydrophobicity of the gas diffusion layers in the cathode and the catalyst loading in the anode with the carbon-supported Ni, synthesized by a polyol process. With the optimal water management and electrode thickness, the MEA constructed using the as-prepared Ni/C anode catalyst containing the metallic and low oxidative state and ultra-low Pt loading cathode reduced the ohmic resistance and mass transfer limitation in the current-voltage curves observed for the alkaline DHFC, achieving an impressive power performance over 500 mW cm^(–2).

关键词： Fuel cell Hydrazine Alkaline media Membrane-electrode assembly

Statistics of oxidation resistance of Ni-(0-15)Co-(8-15)Cr-(0-5)Mo-(0-10)W-(3-8)Al-(0-5)Ti-(0-10)Ta-0.1C-0.01B superalloys at 1000℃ by compositional variations

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Rare Metals 2020年第8期39卷 918-927页

作者： Si-Jun Park Kyu-Hyuk lee Seong-moon Seo Hi-Won Jeong Young-soo Yoo HeeJin Jang Multi-Material Research Center Gwangju-Jeonnam DivisionKorea Automotive Technology InstituteGwangju 62207Republic of Korea Department of Advanced Materials Engineering Chosun UniversityGwangju 61452Republic of Korea High Temperature Materials Group Korea Institute of Materials ScienceChangwon 51508Republic of Korea Department of Materials Science and Engineering Chosun UniversityGwangju 61452Republic of Korea

The effects of alloying elements(Co,Cr,Mo,W,Al,Ti,and Ta)on the oxidation resistance of Ni-(0-15)Co-(8-15)Cr-(0-5)Mo-(0-10)W-(3-8)Al-(0-5)Ti-(0-10)Ta-0.1 C-0.01 B alloys were *** sample compositions were designed by the Box-Behnken method of design of experiments(DOE).The alloying elements show complicated effects on the mass gain due to oxidation,depending on the alloy *** reduces the mass gain *** other elements except Al do not appear to exert a strong effect on the oxidation rate on average,but their influences are shown clearly in the alloys with a low Al ***,W,and Ta reduce the oxidation rate,while Cr,Mo,and Ti promote *** is the most effective element in reducing the oxidation rate of the alloy with a low Al *** is confirmed that a continuous Al2O3 layer is essentially required for high oxidation *** oxide scale of easily oxidized alloys has various oxides such as NiCr2O4,NiAl2O4,NiO,Cr2O3,CrTaO4,and TiO2.

关键词： High temperature oxidation Alloy composition Ni-based superalloy Oxidation resistance Design of experiments

Velocity Profiles between Two Baffles in a Shell and Tube Heat Exchanger

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Journal of Thermal Science 2015年第4期24卷 356-363页

作者： Tae-Hyun Chang Chang-Hoan lee Hae-soo lee Kwon-soo lee Senior Research Fellow of RESEAT Korea Institute of Science and Technology Information Korea Institute of Science and Technology Information Postdoctoral Research Fellow School of Mechanical Engineering of Kyungnam University International University of Korea

Heat exchangers are extensively utilized for waste heat recovery,oil refining,chemical processing,and steam *** this study,velocity profiles are measured using a 3D particle image velocimetry(PIV)system between two baffles in a shell and tube heat exchanger for parallel and counter *** PIV and computational fluid dynamics results show the occurrence of some strong vectors near the *** vectors are assumed due to the clearance between the inner tubes and the front ***,the major parts of the vectors are moved out through the bottom opening of the rear baffle,and other vectors produce a large circle between the two *** simulations are conducted to investigate the effects of the baffle on the heat exchanger using the Fluent *** k-εturbulence model is employed to calculate the flows along the heat exchanger.

关键词： Baffle P1V Shell and tube heat exchanger Cut off ratio CFD

QKD system with fast active optical path length compensation

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Science China(Physics,Mechanics & Astronomy) 2017年第6期60卷 1-7页

作者： Byung Kwon Park Min soo lee Min Ki Woo Yong-Su Kim Sang-Wook Han Sung moon Center for Quantum Information Korea Institute of Science and Technology Department of Nano-materials Science and Engineering Korea University of Science and Technology

We develop a quantum key distribution (QKD) system with fast active optical path length compensation. A rapid and reliable active optical path length compensation scheme is proposed and applied to a plug-and-play QKD system. The system monitors changes in key rates and controls it is own operation automatically. The system achieves its optimal performance within three seconds of operation, which includes a sifted key rate of 5.5 kbps and a quantum bit error rate of less than 2% after an abrupt temperature variation along the 25 km quantum channel. The system also operates well over a 24 h period while completing more than 60 active optical path length compensations.

关键词： quantum key distribution optical path length compensation plug and play field programmable gate array

Immersion Analysis Through Eye-Tracking and Audio in Virtual Reality

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Computers, Materials & Continua 2021年第10期69卷 647-660页

作者： Jihoon lee Nammee moon Department of Computer Science Hoseo UniversityAsan-si31499Korea

In this study,using Head Mounted Display(HMD),which is one of the biggest advantage of Virtual Reality(VR)environment,tracks the user’s gaze in 360◦video content,and examines how the gaze pattern is distributed according to the user’s *** a result of analyzing the gaze pattern distribution of contents with high user immersion and contents with low user immersion through a questionnaire,it was confirmed that the higher the immersion,the more the gaze distribution tends to be concentrated in the center of the *** this experiment,we were able to understand the factors that make users immerse themselves in the VR environment,and among them,the importance of the audio of the content was ***,it was found that the shape of the gaze distribution for grasping the degree of immersion by the subject of the content was *** reviewing the experimental results,we also confirmed the necessity of research to recognize specific objects in a VR environment.

关键词： Virtual reality eye-tracking immersion analysis 360◦video

Block Incremental Dense Tucker Decomposition with Application to Spatial and Temporal Analysis of Air Quality Data

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Computer Modeling in Engineering & Sciences 2024年第4期139卷 319-336页

作者： SangSeok lee HaeWon moon lee Sael Department of Artificial Intelligence Ajou UniversitySuwon-si16499Korea Department of Software and Computer Engineering Ajou UniversitySuwon-si16499Korea

How can we efficiently store and mine dynamically generated dense tensors for modeling the behavior of multidimensional dynamic data?Much of the multidimensional dynamic data in the real world is generated in the form of time-growing *** example,air quality tensor data consists of multiple sensory values gathered from wide locations for a long *** data,accumulated over time,is redundant and consumes a lot ofmemory in its raw *** need a way to efficiently store dynamically generated tensor data that increase over time and to model their behavior on demand between arbitrary time *** this end,we propose a Block IncrementalDense Tucker Decomposition(BID-Tucker)method for efficient storage and on-demand modeling ofmultidimensional spatiotemporal *** that tensors come in unit blocks where only the time domain changes,our proposed BID-Tucker first slices the blocks into matrices and decomposes them via singular value decomposition(SVD).The SVDs of the time×space sliced matrices are stored instead of the raw tensor blocks to save *** modeling from data is required at particular time blocks,the SVDs of corresponding time blocks are retrieved and incremented to be used for Tucker *** factor matrices and core tensor of the decomposed results can then be used for further data *** compared our proposed BID-Tucker with D-Tucker,which our method extends,and vanilla Tucker *** show that our BID-Tucker is faster than both D-Tucker and vanilla Tucker decomposition and uses less memory for storage with a comparable reconstruction *** applied our proposed BID-Tucker to model the spatial and temporal trends of air quality data collected in South Korea from 2018 to *** were able to model the spatial and temporal air quality *** were also able to verify unusual events,such as chronic ozone alerts and large fire events.

关键词： Dynamic decomposition tucker tensor tensor factorization spatiotemporal data tensor analysis air quality

Luminescence properties of Eu^(2+),Gd^(3+) and Pr^(3+) doped translucent Sialon phosphors

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Journal of Rare Earths 2015年第11期33卷 1142-1147页

作者： Bhupendra Joshi soo Wohn lee Research Center for Eco Multi-Functional Nano Materials Sun Moon University

Optical properties of hot pressed Sialon ceramics doped with different rare earth oxides（REOs） i.e. Eu2O3, Gd2O3, and Pr2O3 were investigated. The α-Sialon phase was the main phase obtained after sintering as observed by X-ray diffraction（XRD）. The transparency of different samples of varying thickness measured from UV to IR region revealed that the samples were translucent in the visible region while transparent in IR region. The thin samples of 150 μm thickness had transmittance as high as 30% in the visible region. The luminescence was observed in transmittance mode to investigate the effect of sample thickness on luminescence intensity. We observed blue, yellow and red emissions in Sialon doped with Gd2O3, Eu2O3, and Pr2O3, respectively. The excitation wavelength for Gd2O3 and Pr2O3 doped samples were in UV region i.e. 280 and 270 nm, respectively, whereas, for Eu2O3 doped samples was in the blue region（460 nm）. The Eu2O3 doped Sialon having 300 μm thickness showed better white light extraction as coupled with blue LED. Moreover, the fabricated phosphor samples exhibited high hardness around 20 GPa and fracture toughness above 5 MPa·m1/2.

关键词： Sialon phosphors luminescence rare earth oxides hot pressing