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Indolocarbazole-Based Small Molecule Cathode-Active Material Exhibiting Double Redox for High-Voltage Li-Organic Batteries

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Energy & Environmental Materials 2024年第5期7卷 90-98页

作者： Hyunji Park Hyojin Kye jong-sung lee Young-Chang Joo Dong Joo Min Bong-Gi Kim Soo Young Park Ji Eon Kwon Laboratory for Supramolecular Optoelectronic Materials (LSOM) Department of Materials Science and Engineering Research Institute of Advanced Materials (RIAM) Seoul National University Functional Composite Materials Research Center Jeonbuk Institute of Advanced Composite Materials Korea Institute of Science and Technology (KIST) Department of Organic and Nano System Engineering Konkuk University Department of Materials Science and Engineering Seoul National University Department of JBNU-KIST Industry Academia Convergence Research Jeonbuk National University

Most organic electrode materials （OEMs） for rechargeable batteries employ n-type redox centers, whose redox potentials are intrinsically limited <3.0 V versus Li+/Li. However, p-type materials possessing high redox potentials experience low specific capacities because they are capable of only a single redox reaction within the stable electrochemical window of typical ***, we report 5,11-diethyl-5,11-dihydroindolo[3,2-b]carbazole （DEICZ） as a novel p-type OEM, exhibiting stable plateaus at high discharge potentials of3.44 and 4.09 V versus Li+/Li. Notably, the second redox potential of DEICZ is within the stable electrochemical window. The mechanism of the double redox reaction is investigated using both theoretical calculations and experimental measurements, including density functional theory calculations, ex situ electron spin resonance, and X-ray photoelectron spectroscopy. Finally,hybridization with single-walled carbon nanotubes （SWCNT） improves the cycle stability and rate performance of DEICZ owing to theπ–πinteractions between the SWCNT and co-planar molecular structure of DEICZ, preventing the dissolution of active materials into the electrolyte. The DEICZ/SWCNT composite electrode maintains 70.4%of its initial specific capacity at 1-C rate and also exhibits high-rate capability, even performing well at 100-C rate.

关键词： composite electrodes flexible batteries indolocarbazoles organic rechargeable batteries p-type

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Unsteady Shock-Flow Characteristics in an Over-Expanded Rocket Nozzle

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Journal of Thermal Science 2010年第4期19卷 332-336页

作者： jong sung lee Huey Dong Kim Toshiaki Setoguchi Shigeru Matsuo School of Mechanical Engineering Andong National UniversityAndong760-749Korea Department of Mechanical Engineering Saga University1HonjoSagaJapan

A numerical investigation of transient side-loads in an axisymmetric over-expanded thrust optimized contour nozzle is *** nozzles experience side-loads during start-up and shut-down operations,because of the flow separation at nozzle *** types of flow separations such as FSS and RSS shock structure occur.A two-dimension numerical simulation has been carried out over an axisymmetric TOC nozzle to validate present results and investigate oscillatory flow characteristics for start-up *** Averaged Navier-Stokes equations are numerically solved using a fully implicit finite volume *** equations are solved by coupled implicit *** Stress turbulence model is *** computed pressure at the nozzle wall closely matched with experiment data.A hysteresis phenomenon has been observed between these two shock *** transition from FSS to RSS pattern during start-up process has shown maximum nozzle wall *** wall pressure and shear stress values have shown fluctuations during the FSS to RSS transition. The oscillatory pressure has been observed on the nozzle wall for high pressure *** results have shown that magnitude of the nozzle wall pressure variation is high for the oscillatory phenomenon.

关键词： Free shock separation Over-expansion flow Restricted shock separation Side-loads Supersonic nozzle

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Effect of characteristics and distribution of Mg_(17)Al_(12)precipitates on tensile and bending properties of high-Al-containing Mg alloys

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Journal of Magnesium and Alloys 2024年第2期12卷 779-793页

作者： Sumi Jo Gyo Myeong lee jong Un lee Young Min Kim sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Department of Magnesium Korea Institute of Materials ScienceChangwon 51508Republic of Korea

This study investigates the effect of characteristics and distribution of Mg_(17)Al_(12)precipitates on the uniaxial tensile and three-point bending properties of extruded Mg alloys containing high Al *** extruded Mg–9Al–1Zn–0.3Mn(AZ91)alloy contains lamellar-structured Mg_(17)Al_(12)discontinuous precipitates along the grain boundaries,which are formed via static precipitation during natural air *** extruded Mg–11Al–1Zn–0.3Mn(AZ111)alloy contains spherical Mg_(17)Al_(12)precipitates at the grain boundaries and inside the grains,which are formed via dynamic precipitation during *** to inhomogeneous distribution of precipitates,the AZ111 alloy consists of two different precipitate regions:precipitate-rich region with numerous precipitates and finer grains and precipitate-scarce region with a few precipitates and coarser *** AZ111 alloy exhibits a higher tensile strength than the AZ91 alloy because its smaller grain size and more abundant precipitates result in stronger grain-boundary hardening and precipitation hardening effects,***,the tensile elongation of the AZ111 alloy is lower than that of the AZ91 alloy because the weak cohesion between the dynamic precipitates and the matrix facilitates the crack initiation and *** bending,a macrocrack initiates on the outer surface of bending specimen in both *** AZ111 alloy exhibits higher bending yield strength and lower failure bending strain than the AZ91 *** bending specimens of the AZ91 alloy have similar bending formability,whereas those of the AZ111 alloy exhibit considerable differences in bending formability and crack propagation behavior,depending on the distribution and number density of precipitates in the *** bending specimens of the AZ111 alloy,it is found that the failure bending strain(ε_(f,bending))is inversely proportional to the area fraction of precipitates in the outer zone of bending specimen(A_(ppt)),with a relation

关键词： Mg–Al alloy Extrusion Bending Precipitation Microstructure

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Shape Optimization of a Regenerative Blower Used for Building Fuel Cell System

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Open Journal of Fluid Dynamics 2012年第4期2卷 208-214页

作者： Choon-Man Jang jong-sung lee Environmental Engineering Research Division Korea Institute of Construction Technology Goyang-Si Korea

This paper describes the optimal design of a Cathode blower used for a building fuel cell system. The Cathode air blower has a regenerative blower type. Two design variables, extension angle and number of impeller blade are introduced to enhance the blower performance. Pressure and efficiency of the blower are selected as an object function, and the optimal design is performed by a response surface method. Three-dimensional Navier-Stokes equations are introduced to analyze the performance and internal flow of the blower and to find the value of object function for the training data. Throughout the design optimization, it is found that an extension angle is effective to increase blower efficiency in the blower. The pressure rise for the optimal blower is successfully increased up to 3.17% compared with that of reference one at the design flow rate. It is noted that low velocity region disturbs to make strong recirculation flow in the each blade passage, thus increases local pressure loss. Detailed flow field inside a regenerative blower is also analyzed and compared.

关键词： Regenerative Blower Optimization Response Surface Method Efficiency Pressure

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Mycobacterium ulcerans infection as a cause of chronic diarrhea in an AIDS patient: A case report

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World Journal of Gastroenterology 2008年第5期14卷 808-811页

作者： Jin-Gook Huh You-Sun Kim jong-sung lee Tae-Yeob Jeong Soo-Hyung Ryu Jung-Hwan lee Jeong-Seop Moon Yun-Kyung Kang Myung-Shup Shim Myoung-Don Oh Department of Internal Medicine Inje University College of Medicine Seoul 100-032 South Korea Department of Pathology Inje University College of Medicine Seoul 100-032 South Korea Korean Institute of Tuberculosis Seoul South Korea Department of Internal Medicine Seoul National University College of Medicine Seoul South Korea

Chronic diarrhea is one of the most frequent gastro-intestinal manifestations in acquired immunodeficiency syndrome (AIDS). Protozoa and nontuberculous mycobacteria (NTM) are opportunistic pathogens that can easily infect these patients. Among the NTM, Mycobacterium avium complex (MAC) is the most frequently observed pathogen in HIV-infected patients. However, NTMs other than MAC have not been reported as a gastrointestinal pathogen as yet. We present a case of chronic diarrhea in an AIDS patient in whom Mycobacterium ulcerans and cryptosporidium co-infection is evidenced from colonic tissue.

关键词： Mycobacterium ulcerans Cryptosporidium HIV Chronic diarrhea

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Bidirectional rotating direct-current triboelectric nanogenerator with self-adaptive mechanical switching for harvesting reciprocating motion

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International Journal of Extreme Manufacturing 2024年第4期6卷 324-335页

作者： Donghan lee Joonmin Chae Sumin Cho jong Woo Kim Awais Ahmad Mohammad Rezaul Karim Moonwoo La sung Jea Park Dongwhi Choi Department of Mechanical Engineering(Integrated Engineering Program) Kyung Hee University1732 Deogyeong-daeroYonginGyeonggi 17104Republic of Korea Department of Chemistry University of LahoreLahorePakistan Department of Mechanical Engineering College of EngineeringKing Saud UniversityRiyadh 11421Saudi Arabia School of Mechanical Engineering Korea University of Technology and Education1600 Chungjeol-roCheonanChungnam 31253Republic of Korea

Amid the growing interest in triboelectric nanogenerators(TENGs)as novel energy-harvesting devices,several studies have focused on direct current(DC)TENGs to generate a stable DC output for operating electronic ***,owing to the working mechanisms of conventional DC TENGs,generating a stable DC output from reciprocating motion remains a ***,we propose a bidirectional rotating DC TENG(BiR-TENG),which can generate DC outputs,regardless of the direction of rotation,from reciprocating *** distinct design of the BiR-TENG enables the mechanical rectification of the alternating current output into a rotational-direction-dependent DC ***,it allows the conversion of the rotational-direction-dependent DC output into a unidirectional DC output by adapting the configurations depending on the rotational *** to these tailored design strategies and subsequent optimizations,the BiR-TENG could generate an effective unidirectional DC *** of the BiR-TENG for the reciprocating motions of swinging doors and waves were demonstrated by harnessing this *** study demonstrates the potential of the BiR-TENG design strategy as an effective and versatile solution for energy harvesting from reciprocating motions,highlighting the suitability of DC outputs as an energy source for electronic devices.

关键词： direct-current triboelectric nanogenerator mechanical rectification self-adaptive mechanical design harvesting reciprocation motion

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Porously Reduced 2-Dimensional Bi_(2)O_(2)CO_(3) Petals for Strain-Mediated Electrochemical CO_(2) Reduction to HCOOH

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Energy & Environmental Materials 2024年第1期7卷 215-221页

作者： Won Seok Cho Dae Myung Hong Wan Jae Dong Tae Hyung lee Chul jong Yoo Donghwa lee Ho Won Jang jong-Lam lee Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH)Pohang Gyungbuk 37673Korea Department of Materials Science and Engineering Research Institute of Advanced Materials Seoul National UniversitySeoul 08826Korea

Here we introduce bismuth-based catalysts for the efficient electrochemical reduction of CO_(2)to formic acid(HCOOH),which are composed of petal-shaped Bi_(2)O_(2)CO_(3)(BOC)that spontaneously formed from Bi thin film in aqueous carbonate solution at room *** the electrochemical reduction process,the BOC petals transform to reduced BOC(R-BOC)consisting of individual BOC and Bi *** mismatch between both domains induces biaxial strain at the *** functional theory calculations suggest that the tensile strain on the Bi domain stabilizes the*OCHO intermediate,reducing the thermodynamic barrier toward CO_(2)conversion to *** with the thermodynamic benefit and the unique nanoporous petal-shaped morphology,R-BOC petals have a superior Faradaic efficiency of 95.9%at-0.8 V_(RHE)for the electrochemical conversion of CO_(2)to *** work demonstrates that the spontaneously formed binary phases with desirable lattice strain can increase the activity of bismuth catalysts to the CO_(2)reduction reaction;such a strategy can be applicable in design of various electrocatalysts.

关键词： bismuth carbon dioxide reduction formic acid heterointerfaces strain

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Submicron Ag-coated Cu particles as filler in sintering paste: Suppression of Ag dewetting and improvement of sinterability by surface modification using stearic acid

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Transactions of Nonferrous Metals Society of China 2024年

作者： Yeongjung Kim Yong-sung Eom Kwang-Seong Choi jong-Hyun lee Department of Materials Science and Engineering， Seoul National University of Science and Technology， 232 Gongneung-ro Low-Carbon Integration Tech， Creative Research Section， ETRI， 218 Gajeong-ro Materials Research Institute for Future Convergence， Seoul National University of Science and Technology， 232 Gongneung-ro

Four types of submicron Ag-coated Cu particles with different Ag contents were prepared as sintering paste fillers， and the Ag contents of the particles were measured to be 10， 20， 30， and 40 wt%. Four types of particles （in order of increasing Ag content: A10， A20， A30， and A40） were surface-modified with stearic acid， to suppress the Ag shell dewetting and improve sinterability. The surface-modified particles were mixed with a polyol-based solvent to fabricate a resin-free paste. Subsequently， the pastes were screen-printed onto a slide glass and sintered at 250 ℃ in a nitrogen atmosphere for 1–10 min to form an electrode. The electrical resistivity of the sintered film as a function of sintering time was measured using a four-point probe. All the four surface-modified Cu@Ag particles with different Ag contents exhibited decreased electrical resistivity. Particularly， the largest difference in values after and before the surface modification was observed for A40 with the highest Ag content; the electrical resistivities of the initial and surface-modified particles were 1.51×10-4and 6.67×10-5Ω·cm， respectively， after sintering for 10 min. The findings of this study confirmed that the surface modification using stearic acid effectively suppressed the dewetting of the Ag shell and improved the sinterability of the submicron Cu@Ag particles.

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Organic X-Ray Image Sensors Using a Medium Bandgap Polymer Donor with Low Dark Current

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Energy & Environmental Materials 2024年第6期7卷 230-237页

作者： jong-Woon Ha Seung Hun Eom Bo Kyung Cha Seyeong Song Hyeong Ju Eun jong H.Kim jong Mok Park BongSoo Kim Byoungwook Park Seo-Jin Ko sung Cheol Yoon Changjin lee In Hwan Jung Do-Hoon Hwang Department of Chemistry Chemistry Institute for Functional MaterialsPusan National UniversityBusan 46241Korea Division of Advanced Energy Materials Research Center Korea Research Institute of Chemical Technology(KRICT)Daejeon 34114Korea Electro-Medical Device Research Center Korea Electrotechnology Research Institute(KERI)Ansan 15588Korea Graduate School of Carbon Neutrality School of Energy and Chemical EngineeringUlsan National Institute of Science and Technology(UNIST)Ulsan 44919Korea Department of Molecular Science and Technology Ajou UniversitySuwon 16449Korea Research Center for Advanced Specialty Chemicals Korea Research Institute of Chemical TechnologyUlsan 44412Korea Department of Chemistry Ulsan National Institute of Science and Technology(UNIST)Ulsan 44919Korea Department of Organic and Nano Engineering Human-Tech Convergence ProgramHanyang University222 Wangsimni-roSeongdong-guSeoul 04763Korea

The development of portable X-ray detectors is necessary for diagnosing fractures in unconscious patients in emergency ***,this is quite challenging because of the heavy weight of the scintillator and silicon *** weight and thickness of X-ray detectors can be reduced by replacing the silicon layer with an organic *** study presents a novel bithienopyrroledione-based polymer donor that exhibits excellent photodetection properties even in a thick photoactive layer(~700 nm),owing to the symmetric backbone and highly soluble molecular structure of *** ability of bithienopyrroledione-based polymer donor to strongly suppress the dark current density(Jd~10−10 A cm^(−2))at a negative bias(−2.0 V)while maintaining high responsivity(R=0.29 A W−1)even at a thickness of 700 nm results in a maximum shot-noise-limited specific detectivity of D_(sh)^(*)=2.18×10^(13)Jones in the organic *** organic photodetectors are developed by slot-die coating for use in X-ray detectors,which exhibit D_(sh)^(*)=2.73×10^(12)Jones with clear rising(0.26 s)and falling(0.29 s)response times upon X-ray *** reliability is also proven by linear response of the X-ray detector,and the X-ray detection limit is 3 mA.

关键词： low dark current low detection limit organic photodetector printable X-ray

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Chemical and mechanical properties of stainless, environment-friendly, and nonflammable Mg alloys (SEN alloys): A review

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Journal of Magnesium and Alloys 2024年第3期12卷 841-872页

作者： jong Un lee Hyun Ji Kim Sang-Cheol Jin Ye Jin Kim Young Min Kim Bong Sun You Jun Ho Bae sung Hyuk Park Advanced Metals Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea Department of Materials Science and Metallurgical Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Missile Research Institute Agency for Defense DevelopmentDaejeon 34060Republic of Korea

This review article provides overall understanding of stainless,environment-friendly,and nonflammable Mg alloys(SEN alloys)recently developed at the Korea Institute of Materials *** alloys are produced by adding small amounts of Ca and Y(each<1 wt%)into commercial Mg–Al based alloys,resulting in exceptional ignition and corrosion resistances and impressive mechanical *** main advantages of SEN alloys are as follows.(1)A dense multi-oxide layer of SEN alloys comprising MgO,CaO,and Y_(2)O_(3) impedes the outward dispersion of Mg vapor and the inward penetration of O_(2) during oxidation,thereby enhancing the oxidation and ignition resistances.(2)The presence of Ca-and Y-based second-phase particles in SEN alloys can enhance their corrosion resistance because Ca-containing particles prevent the spread of corrosion,and the replacement of Al-containing particles with less noble ones containing Y(e.g.,Al–Mn–Y or Al–Y particles)retards corrosion.(3)The addition of minor amounts of Ca and Y renders excellent mechanical properties due to improved strengthening *** enhanced properties are attributed to more pronounced dynamic recrystallization and grain refining behaviors caused by the second-phase particles during extrusion.(4)Despite the presence of various types of second-phase particles,the fatigue properties of SEN9 alloys are similar to those of commercial AZ91 alloys.(5)Simultaneous introduction of Ca and Y suppresses the formation of Mg17Al12 discontinuous precipitates during aging,leading to the enhanced elongation of aged SEN alloys.(6)Adding mischmetal into the SEN9 alloy leads to a six-fold enhancement in ***,the studies conducted on SEN alloys demonstrate their excellent ignition and corrosion resistances and mechanical properties,which broaden the industrial applications of Mg alloys by addressing their inherent weaknesses.

关键词： SEN magnesium alloy Corrosion resistance Ignition resistance Mechanical properties Extrudability.

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