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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

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LiTFSI salt concentration effect to digest lithium polysulfides for high-loading sulfur electrodes

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Journal of Energy Chemistry 2023年第3期78卷 574-581页

作者： Jin-Kwang Song Moonsoo kim Seongbae Park young-Jun kim SKKU Advanced Institute of Nano Technology (SAINT) Sungkyunkwan University Department of Nano Engineering Sungkyunkwan University

Sulfur utilization improvement and control of dissolved lithium polysulfide(LiPS;Li2Sx,2 详细信息

Sulfur utilization improvement and control of dissolved lithium polysulfide(LiPS;Li2Sx,2 ility and unstable Li2S electrodeposition,resulting in limited sulfur utilization,especially under high-loading sulfur *** this study,we report on salt concentration effects that improve sulfur utilization with a high-loading cathode(6 mgsulfurcm-2),a high sulfur content(80 wt%) and a low E/S ratio(5 mL gsulfur-1).On the basis of the rapid LiPS dissolving in a low concentration electrolyte,we established that the quantity of Li2S electrodeposition from a high Li+diffusion coefficient,referring to the reduction of LiPS precipitation,was significantly enhanced by a faster *** results demonstrate the importance of kinetic factors for the rate capability and cycle life stability of Li-S battery electrolytes through high Li2S deposition under high-loading sulfur electrode.

关键词： Lithium-sulfur battery Electrolyte concentration Li2S deposition High-loading sulfur electrode

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A unified formulation of optimal guidance-to-collision law for accelerating and decelerating targets

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Chinese Journal of Aeronautics 2022年第7期35卷 40-54页

作者： young-Won kim Boseok kim Chang-Hun LEE Shaoming HE Department of Aerospace Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China

This paper provides a unified formulation of optimal guidance-to-collision law for a target with an arbitrary acceleration or *** collision course for general target acceleration or deceleration is first determined from the engagement geometry in conjunction with the nonlinear engagement kinematics in the proposed *** heading error defined in the collision course is then adopted as a variable to be nullified for accomplishing the intercept *** proposed guidance law is derived based on the heading error dynamics and the optimal error dynamics to ensure optimality and finite-time *** illustrative examples,the proposed guidance command for a constant target acceleration and a target deceleration in the form of a quadratic function of speed are ***,the time-to-go prediction method is suggested for implementing the proposed *** characteristics of the proposed guidance command are analytically investigated to provide insight into the proposed *** key benefits of the proposed method lie in not producing unnecessary guidance commands near a target compared to other methods and ensuring optimality in guidance command even in the nonlinear engagement ***,numerical simulations are performed to validate the proposed method and to show our findings.

关键词： Guidance-to-collision law Optimal guidance Optimal error dynamics Target acceleration or deceleration Unified formulation

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Data Aggregation-based Transmission Method in Ultra-Dense Wireless Networks

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Intelligent Automation & Soft Computing 2023年第1期35卷 727-737页

作者： Dae-young kim Seokhoon kim Department of Computer Software Engineering Soonchunhyang UniversityAsan31538Korea

As the Internet of Things(IoT)advances,machine-type devices are densely deployed and massive networks such as ultra-dense networks(UDNs)are *** devices attend to the network to transmit data using machine-type communication(MTC),whereby numerous,various are *** devices generally have resource constraints and use wireless *** this kind of network,data aggregation is a key function to provide transmission *** can reduce the number of transmitted data in the network,and this leads to energy saving and reducing transmission *** order to effectively operate data aggregation in UDNs,it is important to select an aggregation point *** total number of transmitted data may vary,depending on the aggregation point to which the data are ***,in this paper,we propose a novel data aggregation scheme to select the appropriate aggregation point and describe the data transmission method applying the proposed aggregation *** addition,we evaluate the proposed scheme with extensive computer *** performances in the proposed scheme are achieved compared to the conventional approach.

关键词： Data aggregation data transmission ultra-dense network machine-type communication Internet of Things

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LoRa Backscatter Network Efficient Data Transmission Using RF Source Range Control

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Computers, Materials & Continua 2023年第2期74卷 4015-4025页

作者： Dae-young kim SoYeon Lee Seokhoon kim Department of Computer Software Engineering Soonchunhyang UniversityAsan31538Korea Department of Software Convergence Soonchunhyang UniversityAsan31538Korea

Networks based on backscatter communication provide wireless data transmission in the absence of a power source.A backscatter device receives a radio frequency(RF)source and creates a backscattered signal that delivers data;this enables new services in battery-less domains with massive Internet-of-Things(IoT)*** is highly energy-efficient in the context of massive IoT ***,long-range(LoRa)backscattering facilitates large IoT services.A backscatter network guarantees timeslot-and contention-based ***-based transmission ensures data transmission,but is not scalable to different numbers of transmission *** contention-based transmission is used,collisions are *** reduce collisions and increase transmission efficiency,the number of devices transmitting data must be *** control device activation,the RF source range can be modulated by adjusting the RF source power during LoRa *** reduces the number of transmitting devices,and thus collisions and retransmission,thereby improving transmission *** performed extensive simulations to evaluate the performance of our method.

关键词： Backscatter communication LoRa backscatter RF source range control activated device control internet of things

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Cryptogenic organizing pneumonia associated with pregnancy:A case report

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World Journal of Clinical Cases 2022年第6期10卷 1946-1951页

作者： young Joo Lee young Sun kim Department of Obstetrics and Gynecology Kyung Hee University Medical CenterSeoul 02447South Korea

BACKGROUND Cryptogenic organizing pneumonia(COP),formerly known as bronchiolitis obliterans organizing pneumonia,is an extremely rare disease in *** this case,we report on COP diagnosed in recurrent pneumonia that does not respond to antibiotics in pregnant *** SUMMARY A 35-year-old woman with no prior lung disease presented with concerns of chest pain with cough,sputum,dyspnea,and mild fever at 11 wk’*** was diagnosed with community-acquired pneumonia and treated with antibiotics;her symptoms improved *** weeks after discharge,she was readmitted with aggravated *** computed tomography demonstrated multifocal patchy airspace consolidation and ground-glass opacities at the basal segments of the right lower lobe,at the lateral basal segment of the lower lobe,and at the lingular segment of the left upper *** lavage revealed an increased lymphocyte count and a decreased CD4/CD8 ***(0.5 mg/kg/d)was administered for 10 d after the second *** improved after 3 d of steroid treatment and other symptoms improved on the 5th day of steroid ***-delivery transbronchial lung biopsy further revealed the presence of granulation tissue with fibroblasts in smallbronchiole *** This case suggests that it is important to differentiate COP from atypical pneumonia in the deteriorated condition despite antibiotic treatment.

关键词： Antibiotics Bronchiolitis obliterans organizing pneumonia Corticosteroid Cryptogenic organizing pneumonia Pregnancy Case report

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Byte Frequency Based Indicators for Crypto-Ransomware Detection from Empirical Analysis

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Journal of Computer Science & Technology 2022年第2期37卷 423-442页

作者： Geun Yong kim Joon-young Paik Yeongcheol kim Eun-Sun Cho Department of Computer Science and Engineering Chungnam National UniversityDaejeon 34134South Korea School of Computer Science and Technology Tiangong UniversityTianjin 300387China

File entropy is one of the major indicators of crypto-ransomware because the encryption by ransomware increases the randomness of file ***,entropy-based ransomware detection has certain limitations;for example,when distinguishing ransomware-encrypted files from normal files with inherently high-level entropy,misclassification is very *** addition,the entropy evaluation cost for an entire file renders entropy-based detection impractical for large *** this paper,we propose two indicators based on byte frequency for use in ransomware detection;these are termed EntropySA and DistSA,and both consider the interesting characteristics of certain file subareas termed“sample areas”(SAs).For an encrypted file,both the sampled area and the whole file exhibit high-level randomness,but for a plain file,the sampled area embeds informative structures such as a file header and thus exhibits relatively low-level randomness even though the entire file exhibits high-level *** and DistSA use“byte frequency”and a variation of byte frequency,respectively,derived from sampled *** indicators cause less overhead than other entropy-based detection methods,as experimentally proven using realistic ransomware *** evaluate the effectiveness and feasibility of our indicators,we also employ three expensive but elaborate classification models(neural network,support vector machine and threshold-based approaches).Using these models,our experimental indicators yielded an average Fl-measure of 0.994 and an average detection rate of 99.46%for file encryption attacks by realistic ransomware samples.

关键词： computer security cryptography machine learning ransomware

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Chemical surface tuning of zinc metal anode toward stable,dendrite-less aqueous zinc-ion batteries

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Journal of Energy Chemistry 2023年第11期86卷 1-8,I0001页

作者： Pranav Kulkarni Sun-Sik kim Hyun young Jung Department of Energy Engineering Gyeongsang National UniversityJinju-siGyeongnam 52725South Korea Department of Energy System Engineering Gyeongsang National UniversityJinju-siGyeongnam 52725South Korea

The commercialization of Zn batteries is confronted with urgent challenges in the metal anode,such as dendrite formation,capacity loss,and cracking or ***,surface interfacial engineering of the Zn anode is introduced for achieving safety and dendritic-free cycling for high-performance aqueous Zn batteries through a simple but highly effective chemical etching-substitution *** chemical modification induces a rough peak-valley surface with a thin fluorine-rich interfacial layer on the Zn anode surface,which regulates the growth orientation via guiding uniform Zn plating/stripping,significantly enhances accessibility to aqueous electrolytes and improves wettability by reducing surface *** a result,such a synergetic surface effect enables uniform Zn plating/stripping with low polarization of 29 m V at a current density of 0.5 m A cm^(-2) with stable cyclic performance up to 1000 ***,a full cell composed of a fluorine-substituted Zn anode coupled with aβ-MnO_(2)or Ba-V_(6)O_(13)cathode demonstrates improved capacity retention to 1000 cycles compared to the pristine-Zn *** proposed valley deposition model provides the practical direction of surface-modified interfacial chemistries for improving the electrochemical properties of multivalent metal anodes via surface tuning.

关键词： Dendrite free Peak-Valley surface Zinc-ion batteries Surface modification Fluorinated interface

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Liquid crystal-powered Mie resonators for electrically tunable photorealistic color gradients and dark blacks

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Light(Science & Applications) 2022年第6期11卷 1098-1108页

作者： Trevon Badloe Joohoon kim Inki kim Won-Sik kim Wook Sung kim young-Ki kim Junsuk Rho Department of Mechanical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Department of Biophysics Institute of Quantum BiophysicsSungkyunkwan UniversitySuwon 16419Republic of Korea Department of Intelligent Precision Healthcare Convergence Sungkyunkwan UniversitySuwon 16419Republic of Korea Department of Chemical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Department of Electrical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea POSCO-POSTECH-RIST Convergence Research Center for Flat Optics and Metaphotonics Pohang 37673Republic of Korea National Institute of Nanomaterials Technology(NINT) Pohang 37673Republic of Korea

Taking inspiration from beautiful colors in nature,structural colors produced from nanostructured metasurfaces have shown great promise as a platform for bright,highly saturated,and high-resolution *** plasmonic and dielectric materials have been employed to produce static colors that fulfil the required criteria for high-performance color printing,however,for practical applications in dynamic situations,a form of tunability is *** of the additive color palette of red,green,and blue enable the expression of further colors beyond the three primary colors,while the simultaneous intensity modulation allows access to the full color ***,we demonstrate an electrically tunable metasurface that can represent saturated red,green,and blue pixels that can be dynamically and continuously controlled between on and off states using liquid *** use this to experimentally realize ultrahigh-resolution color printing,active multicolor cryptographic applications,and tunable pixels toward high-performance full-color reflective displays.

关键词： saturated printing colors

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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

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