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Experimental Investigation of Flexible Hawkmoth-like Wings on the Wing-wake Interaction in Hovering Flight

journal of Bionic Engineering 2018年第1期15卷 139-153页

作者： YeongGyun Ryu jo won chang joon Chung Dong-Ha Kim Department of Aerospace Engineering Ryerson University Toronto Ontario M5B 2K3 Canada Department of Aeronautical Science and Flight Operation Korea Aerospace University 76 Hanggongdaehak-ro Deogyang-gu Goyang-si Gyeonggi-do 10540 Republic of Korea Aerodynamics Group Korean Air R&D Center Daejeon Metropolitan City 34054 Republic of Korea

To study wing-wake interaction for various wing flexibilities, force measurements and digital particle image velocimetry were carried out on flapping hawkmoth-like wings in a water tank. Wing thickness was employed as a design variable for the wing flexi- bility distributions. Abrupt flap-down and phase delay in flexible wings influenced the behaviors of the Leading-Edge Vortex （LEV） and Trailing-Edge Vortex （TEV）, generated by the previous stroke. While the rigid wing exhibited a detached LEV at the end of the stroke, wing with specific flexibilities obtained attached LEVs. The attached LEVs induced a relatively rapid flow toward the wing surface as a result of encountering the TEV, and the flow caused a higher lift peak. On the other hand, the wings with larger wing deformations generated distinctive changes in LEV and TEV behaviors. The flap-down helped the TEV form closer to the wing surface, and it thus caused a downwash rather than wing-wake interaction. Furthermore, the most flexible wing had a newly-formed pair of LEVs above the wing during the wing reversal, thereby being not able to generate the wing-wake interaction. These results help to understand the different vortex structures generated by flexible wings during the wing reversal and the corresponding effects of wing-wake interaction.

关键词： hovering flight flexible hawkmoth wings wing-wake interaction Digital Particle Image Velocimetry (DPIV)

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A study on hydrogen uptake and release of a eutectic mixture of biphenyl and diphenyl ether

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journal of Energy Chemistry 2020年第3期29卷 11-16页

作者： Munjeong Jang Byeong Soo Shin Young Suk jo Jeong won Kang Sang Kyu Kwak chang won Yoon Hyangsoo Jeong Center for Hydrogen Fuel Cell Research Korea Institute of Science and Technology(KIST)5 Hwarang-ro 14-gilSeongbuk-guSeoul 02792Republic of Korea Divison of Energy and Environment Technology KIST SchoolKorea University of Science and Technology5 Hwarang-ro 14-gilSeongbuk-guSeoul 02792Republic of Korea Department of Chemical and Biological Engineering Korea UniversityAnam-ro 145Seongbuk-guSeoul 02841Republic of Korea School of Energy and Chemical Engineering Ulsan National Institute of Science and Technology50UNIST-gilUlsan 44919Republic of Korea KHU-KIST Department of Converging Science and Technology Kyung Hee University26 Kyungheedae-roDongdaemun-guSeoul 02447Republic of Korea

Hydrogen storage in Liquid Organic Hydrogen Carrier(LOHC)systems is appealing for the safe storage and distribution of excess renewable energy via existing gasoline infrastructures to *** present the eutectic mixture of biphenyl and diphenyl ether of its first use as a LOHC *** material is hydrogenated with 99%selectivity without the cleavage of C–O bond,with commercial heterogeneous catalysts,which is confirmed by nuclear magnetic spectroscopy and gas chromatography-mass *** concentration,dehydrogenation enthalpy,and thermo-neutral temperature are calculated using a density functional *** results indicate that O-atom-containing material exhibits more favorable dehydrogenation thermodynamics than that of the hydrocarbon *** H2-rich material contains6.8 wt%of gravimetric hydrogen storage capacity.A preliminary study of catalytic dehydrogenation on a continuous reactor is presented to demonstrate a reversibility of this material.

关键词： Hydrogen storage Liquid organic hydrogen carrier Diphenyl ether Dehydrogenation Thermodynamics

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Unilateral versus bilateral Y-type stent-in-stent metal stent insertions in inoperable malignant hilar biliary strictures:A multicenter retrospective study

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Hepatobiliary & Pancreatic Diseases International 2021年第6期20卷 561-567页

作者： Ik Hyun jo chang-Nyol Paik Dae Bum Kim Jaesin Lee jong Yul Lee Jae Hyuck chang Kyu-Hyun Paik won-Suk Park Department of Internal Medicine College of MedicineSt.Vincent’s HospitalThe Catholic University of KoreaSeoulKorea Department of Internal Medicine College of MedicineIncheon St.Mary’s HospitalThe Catholic University of KoreaSeoulKorea Department of Internal Medicine College of MedicineBucheon St.Mary’s HospitalThe Catholic University of KoreaSeoulKorea Department of Internal Medicine College of MedicineDaejeon St.Mary’s HospitalThe Catholic University of KoreaSeoulKorea

Background:To date,there is controversy regarding unilateral versus bilateral stent placement in patients with malignant hilar biliary strictures(MHBSs).The aim of this study was to compare the clinical outcomes and complications of unilateral and bilateral(stent-in-stent method)stent placements for these ***:We conducted a multicenter retrospective analysis of patients with inoperable MHBS who underwent endoscopic self-expandable metal stent(SEMS)placement from January 2009 to December *** groups classified according to the stent procedure method were compared for demographic,procedural,and postprocedure *** analysis for patency loss and overall survival was also ***:A total of 236 subjects were included.A superior technical success rate was found in the unilateral stent group(98.8%vs.82.5%,P<0.001),whereas the clinical success rate was higher in the bilateral group(85.7%vs.70.5%,P=0.028).There was no significant difference with respect to complications or patency loss,and the bilateral group had better overall survival(P<0.01).In the Cox proportional hazard model,MHBSs from lymph node compression were associated with a higher risk of death(HR=9.803,P=0.003).In contrast,bilateral SEMS insertion showed reduced postprocedural mortality(HR=0.316,P=0.001).Conclusions:Y-type stent-in-stent bilateral SEMSs are technically difficult but demonstrated more favorable overall survival for palliative bile drainage of inoperable MHBS patients compared to unilateral insertions.

关键词： Cholestasis Extrahepatic neoplasm Cholangiopancreatography Endoscopy Self-expandable metal stents

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A Novel Goodness of Fit Test Spectrum Sensing Using Extreme Eigenvalues

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Chinese journal of Electronics 2020年第6期29卷 1201-1206页

作者： LI He ZHAO Wenjing LIU chang JIN Minglu YOO Sang-jo School of Information and Communication Engineering Dalian University of Technology Department of Information and Communication Engineering Inha University

The existing Goodness of fit(GoF) test based spectrum sensing algorithms mostly use samples or energies as observations to make decisions,which can hardly achieve satisfactory performance especially when the Primary user(PU) signals are highly ***,the eigenvalue of covariance matrix can reflect signal correlations *** by this,we study the distribution of eigenvalue and propose an eigenvalue based GoF spectrum sensing *** the proposed scheme,we use the ratios of maximum to minimum eigenvalue as observations and thus it can bring performance improvements through capturing correlation of PU *** also provide the related theoretical analysis for the proposed *** results show that the proposed method overcomes the problem of noise uncertainty and achieves performance improvement over the classical samples-based GoF test.

关键词： eigenvalue based GoF spectrum sensing algorithm GoF test based spectrum sensing algorithm primary user signal covariance matrix eigenvalue Radio links and equipment eigenvalues and eigenfunctions signal detection Algebra goodness of fit test spectrum sensing algorithm Linear algebra (numerical analysis) signal sampling signal denoising radio spectrum management correlation methods covariance matrices Signal detection signal correlation

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Highly ordered lead-free double perovskite halides by design

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journal of Materiomics 2020年第4期6卷 651-660页

作者： chang won Ahn Jae Hun jo jong Chan Kim Hamid Ullah Sangkyun Ryu Younghun Hwang Jin San Choi jongmin Lee Sanghan Lee Hyoungjeen Jeen Young-Han Shin Hu Young Jeong Ill won Kim Tae Heon Kim Department of Physics and Energy Harvest-Storage Research Center(EHSRC) University of UlsanUlsan44610Republic of Korea UNIST Central Research Facilities(UCRF)&School of Materials Science and Engineering Ulsan National Institute of Science and Technology(UNIST)Ulsan44919Republic of Korea Multiscale Materials Modelling Laboratory Department of PhysicsUniversity of UlsanUlsan44610Republic of Korea Department of Physics Pusan National UniversityPusan46241Republic of Korea School of Electrical and Electronics Engineering Ulsan CollegeUlsan44610Republic of Korea School of Materials Science and Engineering Gwangju Institute of Science and TechnologyGwangju61005Republic of Korea

Lead-free double perovskite halides are emerging optoelectronic materials that are alternatives to leadbased perovskite ***,single-crystalline double perovskite halides were synthesized,and their intriguing functional properties were *** such pioneering works,lead-free double perovskite halides with better crystallinity are still in demand for applications to novel optoelectronic ***,we realized highly crystalline Cs2AgBiBr6 single crystals with a well-defined atomic ordering on the microscopic *** avoided the formation of Ag vacancies and the subsequent secondary Cs3Bi2Br9 by manipulating the initial chemical environments in hydrothermal *** suppression of Ag vacancies allows us to reduce the trap density in the as-grown crystals and to enhance the carrier mobility *** design strategy is applicable for fabricating other lead-free halide materials with high crystallinity.

关键词： Cs2AgBiBr6 Lead-free Double perovskite Single crystal

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Advancing Li-ion storage performance with hybrid vertical carbon/Ni_(3)S_(2)-based electrodes

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journal of Energy Chemistry 2022年第4期31卷 8-18页

作者： Neelakandan M.Santhosh Nitheesha Shaji d Petra Stražar Gregor Filipič Janez Zavašnik chang won Ho Murugan Nanthagopal chang Woo Lee UrošCvelbar Department of Gaseous Electronics(F6) Jožef Stefan InstituteJamova cesta 39SI-1000 LjubljanaEUSlovenia jožef Stefan International Postgraduate School Jamova cesta 39SI-1000 LjubljanaEUSlovenia Faculty of Mathematics and Physics University of LjubljanaJadranska cesta 19SI-1000 LjubljanaEUSlovenia Department of Chemical Engineering(Integrated Engineering) College of EngineeringKyung Hee University1732 Deogyeong-daeroGiheungYonginGyeonggi 17104South Korea Center for the SMART Energy Platform College of EngineeringKyung Hee University1732 Deogyeong-daeroGiheungYonginGyeonggi 17104South Korea

Conversion-reaction induced charge storage mechanisms of transition metal sulphides have received considerable interest in designing high-capacity electrodes for electrochemical energy storage ***,their low conductivity and structural degradation during cycling limit their applications as energy storage devices.A combination of different nickel sulphide phases tailored with carbon nanostructures is suggested to address these ***,a facile,two-step approach is demonstrated for fabricating a hybrid electrode,consisting of trinickel disulphide(Ni_(3)S_(2))formed on a metallic Ni nanoparticle supported by vertical carbon nanotubes(VCN)backbone in the form Ni_(3)S_(2)/Ni@***_(3)S_(2)/Ni@VCN electrodes were tested as anode for lithium-ion batteries,and the electrode featured outstanding lithiumstorage capabilities with a high reversible capacity(1113 m Ah g^(-1) after 100 cycles at 100 m A g^(-1)),excellent long-term cycling stability(770 m Ah g^(-1) after 500 cycles at 200 m A g^(-1)),and good rate *** resulting electrode performance is one of the best Li-ion storage capabilities in the Ni_(3)S_(2)-type anode materials described.A unique “broccoli-like”structure of polycrystalline Ni_(3)S_(2)capped on conductive VCN backbone helps the interface storage process and boosts lithium storage performance.

关键词： Ni_(3)S_(2) Vertical carbon nanostructures Hierarchical structures Binder-free electrode Lithium-ion batteries

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Intra-arterial lipo-prostaglandin E1 infusion for arterial spasm in liver transplantation:A case report

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World journal of Clinical Cases 2023年第34期11卷 8153-8157页

作者： Moonhwan Kim Hae won Lee chang Jin Yoon Boram Lee Yeongsoo jo Jai Young Cho Yoo-Seok Yoon Jun Suh Lee Ho-Seong Han Department of Surgery Seoul National University Bundang HospitalSeoul National University College of MedicineSeongnam-si 13620Gyeonggi-doSouth Korea Department of Radiology Seoul National UniversitySeongnam 463-707South Korea

BACKGROUND Hepatic artery obstruction is a critical consideration in graft outcomes after living donor liver *** report a case of diffuse arterial vasospasm that developed immediately after anastomosis and was managed with an intra-arterial infusion of lipo-prostaglandin E1(PGE1).CASE SUMMARY A 57-year-old male with hepatitis B virus-related liver cirrhosis and hepatocellular carcinoma underwent ABO-incompatible living donor liver *** grafted hepatic artery was first anastomosed to the recipient’s right hepatic artery ***,the arterial pulse immediately *** a new anastomosis was performed using the right gastroepiploic artery,the patient’s arterial pulse rate remained *** attempted angiographic intervention immediately after the operation;it showed diffuse arterial vasospasms like‘beads on a string’.We attempted continuous infusion of lipo-PGE1 overnight via an intra-arterial *** next day,arterial flow improved without any spasms or *** patient had no additional arterial complications or related sequelae at the time of writing,1-year post-liver *** Angiographic evaluation is helpful in cases of repetitive arterial obstruction,and intra-arterial infusion of lipo-PGE1 may be effective in treating diffuse arterial spasms.

关键词： Liver transplantation Hepatic artery Vasospasm Prostaglandin E1 Intervention Case report

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Polarization reversal via a transient relaxor state in nonergodic relaxors near freezing temperature

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journal of Materiomics 2019年第4期5卷 634-640页

作者： chang-Hyo Hong Hanzheng Guo Xiaoli Tan john E.Daniels Wook jo School of Materials Science and Engineering Ulsan National Institute of Science and TechnologyUlsan44919Republic of Korea Department of Materials Science and Engineering Iowa State UniversityAmesIA50011USA School of Materials Science and Engineering University of New South WalesNew South Wales2052Australia

Among the unresolved issues in the study of relaxor ferroelectrics is the role of freezing temperature,across which the dynamics of polarization reversal in relaxor ferroelectrics *** presence of this freezing temperature is best manifested by the appearance of a double polarization hysteresis loop just above the freezing *** that the polarization pinching evolving into a double hysteresis starts well below the freezing temperature,there exists a transient temperature regime between the nonergodic and the ergodic relaxor *** clarify the role of the freezing temperature on the pinching,the polarization reversal near the freezing temperature of relaxor(Pb_(1-x)La_(x))(Zr_(1-y)T_(y))_(1-x/4)O_(3)(PLZT)was monitored using three in situ electric field methods:electrocaloric effect,neutron diffraction,and transmission electron *** demonstrate that the pinching results from a two-step process,1)domain detexturization in the ferroelectric state and 2)miniaturization of *** observation explains the recently reported gap between the depolarization temperature T_(d) and the ferroelectric-torelaxor transition temperature T_(F-R) in lead-free *** further show that T_(d) and T_(F-R),which have long been considered identical in lead-based relaxors,are not the *** current study suggests that the mismatch between T_(d) and TF-R is an inherent feature in both lead-based and lead-free relaxor ferroelectrics.

关键词： Relaxor Nanodomains In situ Neutron diffraction Transmission electron microscopy

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Thermal stability and mechanical properties of thick thermal barrier coatings with vertical type cracks

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Transactions of Nonferrous Metals Society of China 2014年第S1期24卷 29-35页

作者： Zhe LU Min-Sik KIM Sang-won MYOUNG Je-Hyun LEE Yeon-Gil JUNG In-Soo KIM chang-Yong jo School of Nano & Advanced Materials Engineering Changwon National University High Temperature Materials Research Group Korea Institute of Materials Science

The thermal stability and failure mechanism of thick thermal barrier coatings(TBCs) with and without vertical type cracks were investigated through the cyclic thermal exposure and thermal-shock tests. The TBC systems with thickness of about 2000 μm in the top coat were prepared by an air plasma spray(APS) on the bond coat of about 150 μm in thickness prepared by APS. The adhesive strength values of the as-prepared TBCs with and without vertical type cracks were determined to be 24.7 and 11.0 MPa, respectively, indicating the better interface stability in the TBC with vertical type cracks. The TBC with vertical type cracks shows a better thermal durability than that without vertical type cracks in the thermal cyclic exposure and thermal-shock tests. The hardness values of the as-prepared TBCs with and without vertical type cracks were found to be 6.6 and 5.3 GPa, respectively, which were increased to 9.5 and 5.5 GPa, respectively, after the cyclic thermal exposure tests. These results indicate that the vertical type cracks developed in the top coat are important in improving the lifetime performance of thick TBC in high temperature environment.

关键词： thermal barrier coating air plasma spray vertical type crack thermal durability

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Effect of serum testosterone and percent tumor volume on extra-prostatic extension and biochemical recurrence after laparoscopic radical prostatectomy

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Asian journal of Andrology 2016年第1期18卷 54-59页

作者： Eu chang Hwang Seong Hyeon Yu Yang Hyun jo Seung I1 Jung Taek won Kang Dong Deuk Kwon Chan Choi Suk Hee Heo Jun Eul Hwang Sung-Hoon Jung Tae-Young Jung Department of Urology Chonnam National University Medical School Gwangju Republic of Korea Department of Pathology Chonnam National University Medical School Gwangju Republic of Korea Department of Radiology Chonnam National University Medical School Gwangju Republic of Korea Department of Hemato-oncology Chonnam National University Medical School Gwangju Republic of Korea Department of Neurosurgery Chonnam National University Medical Schoo Gwangju Republic of Korea

Several studies have revealed that the preoperative serum testosterone and percent tumor volume （PTV） predict extra-prostatic extension （EPE） and biochemical recurrence （BCR） after radical prostatectomy. This study investigated the prognostic significance of serum testosterone and PTV in relation to EPE and BCR after laparoscopic radical prostatectomy （LRP）. We reviewed 520 patients who underwent LRP between 2004 and 2012. PTV was determined as the sum of all visually estimated tumor foci in every section. BCR was defined as two consecutive increases in the postoperative prostate-specific antigen （PSA）〉0.2 ng ml^-1. The threshold for serum total testosterone was 3.0 ng ml^-1, Multivariate logistic regression was used to define the effect of variables on the risk of EPE and BCR. A low serum testosterone （〈3.0 ng ml^-1） was associated with a high serum PSA, Gleason score, positive core percentage of the prostate biopsy, PTV, and all pathological variables. On multivariate analysis, similar to previous studies, the serum PSA, biopsy positive core percentage, Gleason score, and pathological variables predicted EPE and BCR. In addition, low serum testosterone （〈3.0 ng ml^-1, adjusted OR, 8.52; 95% CI, 5.04-14.4, P = 0.001） predicted EPE and PTV （adjusted OR, 1.02; 95% CI, 1.01-1.05, P = 0.046） predicted BCR. In addition to previous predictors of EPE and BCR, low serum testosterone and PTV are valuable predictors of EPE and BCR after LRP.

关键词： biochemical recurrence extra-prostatic extension prostate neoplasms prostatectomy testosterone tumor burden

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