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Journal of Materials Science & Technology 2020年第2期37卷 19-25页

作者： Min Su Park Jin Kyu kim Tong-Seok Han Jung Tae Park Jong hak kim Department of Chemical and Biomolecular Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul03722Korea Department of Civil and Environmental Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul03722Korea Department of Chemical Engineering Konkuk University120 Neungdong-roGwangjin-guSeoul05029Korea

We report a composite material with the high tribological performance,which consists of onedimensional SnO2 nanotubes(ST)and a high molecular weight poly(vinylidene fluoride)(PVDF)matrix in terms of *** of PVDF in N,N-dimethylformamide(DMF)resulted in a facile penetration of PVDF into the inner hollow voids of ST,leading to the close *** between PVDF and ST results in a beneficial effect on the chain arrangement of PVDF,providing anα-phase with better tribological *** ST incorporation,the friction coefficient decreased by 85.0%to 0.408,and the specific wear rate decreased by 69.1%to 0.412,demonstrating the pivotal role of ST as a self-lubricating material due to a large interactive area and PVDF chain rearrangement.

关键词： SnO2 nanotube Composite Friction coefficient Wear rate

k-Nearest Neighbor Query Processing Algorithms for a Query Region in Road Networks

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Journal of Computer Science & Technology 2013年第4期28卷 585-596页

作者： Hyeong-Il kim jae-Woo Chang Department of Computer Engineering Chonbuk National University Cloud Open R&D Center Chonbuk National University

Recent development of wireless communication technologies and the popularity of smart phones .are making location-based services （LBS） popular. However, requesting queries to LBS servers with users＇ exact locations may threat the privacy of users. Therefore, there have been many researches on generating a cloaked query region for user privacy protection. Consequently, an efficient query processing algorithm for a query region is required. So, in this paper, we propose k-nearest neighbor query （k-NN） processing algorithms for a query region in road networks. To efficiently retrieve k-NN points of interest （POIs）, we make use of the Island index. We also propose a method that generates an adaptive Island index to improve the query processing performance and storage usage. Finally, we show by our performance analysis that our k-NN query processing algorithms outperform the existing k-Range Nearest Neighbor （kRNN） algorithm in terms of network expansion cost and query processing time.

关键词： island index k-nearest neighbor query processing scheme locatiombased service road network

Early experience of the compression anastomosis ring (CAR^(TM) 27) in left-sided colon resection

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World Journal of Gastroenterology 2011年第43期17卷 4787-4792页

作者： Jung-Yeon Lee Jin-Hee Woo Hong-Jo Choi Ki-jae Park Young-Hoon Roh Ki-Han kim hak-Yoon Lee Department of Surgery Dong-A University Medical Center

AIM:To evaluate clinical validity of the compression anastomosis ring(CARTM27) anastomosis in left-sided colonic resection. METHODS:A non-randomized prospective data collection was performed for patients undergoing an elective left-sided colon resection,followed by an anastomosis using the CARTM27 between November 2009 and January *** criteria of the use of the CARTM27 were anastomoses between the colon and at or above the intraperitoneal *** primary short-term clinical endpoint,rate of anastomotic leakage,and other clinical outcomes,including intraand postoperative complications,length of operation time and hospital stay,and the ring elimination time were evaluated. RESULTS:A total of 79 patients(male,43;median age,64 years) underwent an elective left-sided colon resection,followed by an anastomosis using *** was performed laparoscopically in 70 patients,in whom two patients converted to open procedure(2.9%) .There was no surgical *** an intraoperative complication,total disruption of the anastomosis occurred by premature enforced tension on the proximal segment of the anastomosis in one *** ring was removed and another new CARTM27 anastomosis was *** patient with sigmoid colon cancer showed postoperative anastomotic leakage after 6 d postoperatively and temporary diverting ileostomy was *** date of expulsion of the ring could not be recorded because most patients were not aware that the ring had been *** patients manifested clinical symptoms of anastomotic stricture. CONCLUSION:Short-term evaluation of the CARTM27 anastomosis in elective left colectomy suggested it to be a safe and efficacious alternative to the standard hand-sewn or stapling technique.

关键词： Compression anastomosis Colon Anastomotic leakage CARTM27

Selectively patterned TiO2 nanorods as electron transport pathway for high performance perovskite solar cells

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Nano Research 2019年第3期12卷 601-606页

作者： Daihong Huh KyoungSuk Oh Minjin kim hak-Jong Choi Dong Suk kim Heon Lee Department of Materials Science and Engineering Korea University Anam-ro 145 Sungbuk-Gu Seoul 136-701 Republic cf Korea KIER-UNIST Advanced Center for Energy Korea Institute of Energy Research (KIER) UNIST-Gil 50 Eonyang-eup Ulju-gun Ulsan 689-851 Republic of Korea Department of Electrical and Systems Engineering University of Pennsylvania Philadelphia Pennsylvania 19104 USA

Organic-inorganic hybrid perovskite solar cells (PSCs) are attracting tremendous attention for new-generation photovoltaic devices because of their excellent power conversion efficiency and simple fabrication process. One of the various approaches to increase the efficiency of PSCs is to change the material or structure of the carrier transport layer. Here, optically long and electrically short structural concept is proposed to enhance the characteristics of a PSC by employing selectively grown single crystalline TiO2 nanorods. The approach has the merit of increasing the electro n-hole separati on effectively and en ables a thicker active layer to be coated without electrical loss by using TiO2 nano rods as an electr on pathway. Moreover, selectively grow n TiO2 nano rods in crease the optical path of the in cide nt light via scatteri ng effects and en able a smooth coati ng of the active layer. Nano imprint lithography and hydrothermal growth were employed to fabricate selectively grow n TiO2 nanorod substrates. The fabricated solar cell exhibits an efficiency of 19.86% with a current density, open-circuit voltage, and fill factor of 23.13 mA/cm^2, 1.120 V, and 76.69%, respectively. Time-resolved photoluminescence, ultraviolet-visible (UV-Vis) spectroscopy, and the incident phot on to current efficiency (IPCE) an alysis were conducted to understand the factors resp on sible for the improvement in characteristics of the fabricated PSCs.

关键词： perovskite solar cells patter ned T1O2 nanorods nanoimprint lithography

Comparison of electrochemical properties of atmospheric pressure plasma coatings for Al_2O_3-3TiO_2 and CoNiCrAlY in sea water

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中国有色金属学会会刊：英文版 2012年第S3期22卷 745-752页

作者： Seong-jong kim Seong-kweon kim jae-cheul PARK Division of Marine Engineering Mokpo Maritime University Department of Electronic IT Media Engineering Institue of TechnologySeoul National University of Science and Technology New Growth Technical Support Team Green and Industrial Technology CenterKorean Register of Shipping

To improve the durability of underwater rotating products,the corrosion characteristics in harsh marine environment were evaluated through various electrochemical experiments on the Al2O3-3TiO2 and CoNiCrAlY coating layers by atmospheric pressure plasma spray coating *** evaluating the corrosion resistance of these materials,their applicability to environmentally friendly power generation equipment such as blades of tidal current turbines was *** to the Tafel analysis for micro-areas including the coating layer,the coating/metal interlayer and the base metal,the Al2O3-3TiO2 coating layer and the CoNiCrAlY coating layer show markedly lower corrosion current density than the base *** corrosion current density of the CoNiCrAlY coating layer (9.75316×10-8A/cm2) is about 1.6 times more than that of the Al2O3-3TiO2 coating layer (6.13139×10-8A/cm2).

关键词： Al2O3-3TiO2 coating layer CoNiCrAlY coating layer underwater rotating products marine environment corrosion characteristics atmospheric pressure plasma spray

Comparison of mesophilic and thermophilic anaerobic digestions of thermal hydrolysis pretreated swine manure: Process performance,microbial communities and energy balance

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Journal of Environmental Sciences 2023年第4期126卷 222-233页

作者： Xiaohui Liu Changmin Lee jae Young kim Department of Civil and Environmental Engineering Seoul National UniversitySeoul 08826Korea

Anaerobic digestion (AD) of swine manure (SM) commonly shows low biogas output and unsatisfactory economic performance. In this study, thermophilic AD (TAD, 50±1℃) was combined with thermal hydrolysis pretreatment (THP, 170℃/10 bar), to investigate its potential for maximizing biogas yield, securing successful digestion and microbial diversity, as well as improving energy balance. Four lab-scale continuously stirred tank reactors were operated for 300 days and compared with each other, i.e., reactor 1 (raw SM fed in mesophilic AD:RSM-MAD), reactor 2 (THP-treated SM fed in MAD:TSM-MAD), reactor 3 (RSM-TAD),and reactor 4 (TSM-TAD). The results showed that THP was efficient to increase methane production of SM, TSM-TAD mode led to the highest methane yield (129.8±40.5 mL-CH_(4)/gVS/day) among the tests (p 700 mg/L) or volatile fatty acids (> 6000 mg/L) accumulation compared with MAD in start-up phase, TSM-TAD treatment mode behaved a sustainable digestion process in a long-term operation. For TSM-TAD scenario, higher Shannon–Weaver (3.873) and lower Simpson index (0.061) indicated this mode ensured and enlarged the diversity of bacteria communities. Phylum Bathyarchaeota was dominant (59.3%-90.0%) in archaea community,followed by Euryarchaeota in the four reactors. RSM-MAD treatment mode achieved the highest energy output (4.65 GJ/day), TSM-TAD was less effective (-17.38 GJ/day) due to increased energy demands. Thus improving the energetic efficiency of THP units is recommended for the development of TSM-TAD treatment mode.

关键词： Thermal hydrolysis pretreatment Digestion temperature Process performances Microbial communities Energy balance

Infrared-harvesting colloidal quantum dot inks for efficient photovoltaics: Impact of surface chemistry and device engineering

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Journal of Materials Science & Technology 2023年第16期147卷 224-240页

作者： Younghoon kim Min-jae Choi Jongmin Choi Department of Chemistry Kookmin UniversitySeoul02707Republic of Korea Department of Chemical and Biochemical Engineering Dongguk UniversitySeoul04620Republic of Korea Department of Energy Science and Engineering Daegu Gyeongbuk Institute of Science and Technology(DGIST)Daegu42988Republic of Korea

Colloidal quantum dots(CQDs)are promising semiconducting materials,which can be used as a photoactive layer in various optoelectronic applications,because of their size-tunable bandgap energy,solution processability,and excellent optical and optoelectronic *** particular,these features have generated great interest in the development of CQD solar cells and led to a rapid increase in their power conversion *** improvements were enabled by many innovative approaches in terms of CQD’s surface chemistry and device architecture *** this review,a critical overview of the research progress in CQD solar cells is presented with a focus on the strategies adopted for achieving record efficiency in CQD solar *** strategies include the use of organic/inorganic surface ligands,pre-and post-treatment of CQDs,and solid-state/solution-phase ligand ***,we provide an understanding of the research history to inspire the rational design of next-generation CQD optoelectronic devices,such as solar cells,light-emitting diodes,and *** research on the development of infrared CQD solar cells as complementary platforms to other solar cell technologies is also critically discussed to provide another perspective on CQD technologies.

关键词： Quantum dot Lead sulfide Ligand exchange Colloidal ink Infrared light Solar cell

Opportunities and challenges in cathode development for non-lithium-ion batteries

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eScience 2024年第4期4卷 1-6页

作者： Haegyeom kim jae Chul kim Materials Sciences Division Lawrence Berkeley National Laboratory94720CAUSA Department of Chemical Engineering and Materials Science Stevens Institute of Technology07030NJUSA

Lithium(Li)-ion batteries have stimulated the societal transformation to clean energy *** carry-on electricity is revolutionizing how society communicates,functions,and evolves efficiently by enabling mobile electronics,zero-emission electric vehicles,and stationary energy *** preparation for the sustainable energy future,however,there are growing concerns about depleting critical elements used in the Li technology(e.g.,lithium,cobalt,and nickel),especially for large-scale applications that will accelerate the rate of elemental *** non-Li-based rechargeable batteries composed of earth-abundant elements,such as sodium,potassium,magnesium,and calcium,have been proposed and explored as alternative systems to promote sustainable development of energy *** this perspective,we discuss challenges in Li-ion batteries in the sustainability aspect and provide our opinions on the potential applications of non-Li-based *** also highlight the current status,important progress,and remaining challenges of the Li-alternative technologies.

关键词： Batteries Sodium Potassium Lithium Multi-valent Energy storage

Tribological properties of multilayer tetrahedral amorphous carbon coatings deposited by filtered cathodic vacuum arc deposition

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Friction 2021年第5期9卷 1292-1302页

作者： Young-Jun JANG jae-Il kim WooYoung LEE Jongkuk kim Department of Extreme Environmental Coatings Surface Technology DivisionKorea Institute of Materials Science(KIMS)Gyeongnam-do 51508Republic of Korea Department of Mechanical Science and Engineering Graduate School of EngineeringNagoya UniversityNagoya 464-8603Japan

Tetrahedral amorphous carbon(ta‐C)has emerged as an excellent coating material for improving the reliability of application components under high normal ***,we present the results of our investigations regarding the mechanical and tribological properties of a 2‐μm‐thick multilayer ta‐C coating on high‐speed steel *** composed of alternating soft and hard layers are fabricated using filtered a cathodic vacuum arc with alternating substrate bias voltages(0 and 100 V or 0 and 150 V).The thickness ratio is discovered to be 1:3 for the sp2‐rich and sp3‐rich *** results show that the hardness and elastic modulus of the multilayer ta‐C coatings increase with the sp3 content of the hard *** hardness reached approximately 37 GPa,whereas an improved toughness and a higher adhesion strength(>29 N)are *** friction performance(μ=0.07)of the multilayer coating is similar to that of the single layer ta‐C thick coating,but the wear rate(0.13×10^(–6) mm^(3)/(N∙m))improved under a high load of 30 *** further demonstrate the importance of the multilayer structure in suppressing crack propagation and increasing the resistance to plastic deformation(H3/E2)ratio.

关键词： tetrahedral amorphous carbon(ta‐C) filtered cathodic vacuum arc deposition multilayer coatings alternating substrate bias voltage wear resistance plastic deformation resistance

Integrating Hormone- and Micromolecule- Mediated Signaling with Plasmodesmal Communication

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Molecular Plant 2016年第1期9卷 46-56页

作者： Xiao Han jae-Yean kim Biotechnology Research Institute Chinese Academy of Agricultural Science Beijing 100081 China Division of Applied Life Science (BK21 plus program) Plant Molecular Biology & Biotechnology Research Center Gyeongsang National University Jinju 660-701Korea

Intercellular and supracellular communications through plasmodesmata are involved in vital processes for plant development and physiological responses. Micro- and macromolecules, including hormones, RNA, and proteins, serve as biological information vectors that traffic through the plasmodesmata between cells. Previous studies demonstrated that the plasmodesmata are elaborately regulated, whereby a long queue of multiple signaling molecules forms. However, the mechanism by which these signals are coupled or coor- dinated in terms of simultaneous transport in a single channel remains a puzzle. In the last few years, several phytohormones that could function as both non-cell-autonomous signals and plasmodesmal regulators have been disclosed. Plasmodesmal regulators such as auxin, salicylic acid, reactive oxygen species, gibberellic acids, chitin, and jasmonic acid could regulate intercellular trafficking by adjusting plasmodesmal permeability. Here, callose, along with β-glucan synthase and β-glucanase, plays a critical role in regulating plasmodesmal permeability. Interestingly, most of the previously identified regulators are capable of diffusing through the plasmodesmata. Given the small sizes of these molecules, the plasmo- desmata are prominent intercellular channels that allow diffusion-based movement of those signaling molecules. Obviously, intercellular communication is under the control of a major mechanism, named a feedback loop, at the plasmodesmata, which mediates complicated biological behaviors. Prospective research on the mechanism of coupling micromolecules at the plasmodesmata for developmental signaling and nutrient provision will help us to understand how plants coordinate their development and photosynthetic assimilation, which is important for agriculture.

关键词： callose cell-to-cell movement hormone intercellular signaling plasmodesmata