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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

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

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

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

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

Formation of photo-reactive heterostructure from a multicomponent amorphous alloy with atomically random distribution

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Journal of Materials Science & Technology 2022年第14期109卷 245-253页

作者： Hae Jin Park Hee Jin Lee Tae Kyung kim Sung Hwan Hong Wei-Min Wang taek Jib Choi Ki Buem kim Department of Nanotechnology and Advanced Materials Engineering Sejong University209 Neung dong-roGwangjin-guSeoul 05006Republic of Korea Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials Ministry of EducationShandong UniversityJinan 250061China

In this study,metallic glass is designed tunable for promising functional applications via a facile and stable,one-step *** approach about alloy design and process is based on the unique properties of the Ti-Cu-Ni-Sn metallic glass that are afforded by the varying oxygen affinities of the four constituent *** metallic glass exhibits homogeneous nucleation of oxides and uniform formation of the various metal *** alloy design and hydrothermal synthesis to customize the metallic glasses are the most critical factors that determine the characteristics of the metal oxides and the resulting nanostructures and photoelectrode *** enables the desired element to be selectively grown via a facile single-step *** results provide a promising road map for the application of metallic glasses to photoelectrochemical(PEC)solar water splitting,as well as various other new possibilities.

关键词： Metallic glass Alloy design Hydrothermal synthesis Metal oxide Water splitting

Application of automated cone penetrometer for railway investigation using correlations with DCPI and deflection modulus

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Research in Cold and Arid Regions 2022年第4期14卷 235-238页

作者： Sang Yeob kim Won-taek Hong Jong-Sub Lee School of Civil Environmental and Architectural EngineeringKorea UniversitySeoul 02841Republic of Korea Department of Civil&Environmental Engineering Gachon UniversitySeongnam-si 13120Republic of Korea

Portable in-situ devices have been used for characterizing low accessible field,such as the railway *** this study,the automated cone penetrometer(ACP)was designed for the application on the railway *** is composed of the cone tip,driving rod,and hydraulic hammer *** hydraulic motor lifts and drops the 294.3 N hammer from a height of 200 mm such that the potential energy of 58.9 N m impacts the driving *** N-value(NACP)from the ACP test was compared with the dynamic cone penetration index(DCPI)from the dynamic cone penetrometer(DCP)*** test results show that the NACP and DCPI profiles show opposite trend owing to the inverse concept of the *** the correlation of DCPI and NACP,the limitation of DCPI reveals owing the minimum manually measured value of 1 mm/***,the evaluation of the deflection modulus(EFWD)using NACP is more efficient than that using *** on the result of this study,we suggest that ACP can be used for strength and stiffness evaluation of railway subgrade rapidly and reliably.

关键词： Automated cone penetrometer DCPI E_(FWD )N_(ACP) Railway subgrade

Prediction of high thermoelectric performance in the lowdimensional metal halide Cs_(3)Cu_(2)I_(5)

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npj Computational Materials 2021年第1期7卷 476-481页

作者： young-Kwang Jung In taek Han Yong Churl kim Aron Walsh Department of Materials Science and Engineering Yonsei UniversitySeoulSouth Korea Samsung Advanced Institute of Technology(SAIT) Samsung Electronics Materials Research ComplexYoungtongSuwonSouth Korea Department of Materials Imperial College LondonLondonUK

Metal halides have emerged as a new generation of semiconductors with applications ranging from solar cells to chemical *** assess the thermoelectric potential of Cs_(3)Cu_(2)I_(5),which has a crystal structure formed of zero-dimensional[Cu_(2)I_(5)]3−anionic clusters that are separated by Cs+counter *** find the compound exhibits the characteristics of a phonon-glass electroncrystal with a large imbalance in the conduction of heat and electrons predicted from first-principles transport *** anharmonic phonon–phonon scattering results in short-lived acoustic vibrations and an ultra-low lattice thermal conductivity(10 cm^(2)V^(−1)s^(−1)).For an n-type crystal at 600 K,a thermoelectric figure-of-merit ZT of 2.6 is found to be accessible,which for a cold source of 300 K corresponds to a thermodynamic heat-to-electricity conversion efficiency of 15%.

关键词： theory phonon crystal

Investigation of long-wavelength elastic wave propagation through wet bentonite-filled rock joints

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第10期15卷 2496-2507页

作者： Ji-Won kim Song-Hun Chong Jin-Seop kim Geon-young kim Disposal Performance Demonstration R&D Division Korea Atomic Energy Research InstituteDaejeon34057Republic of Korea Department of Civil Engineering Sunchon National UniversitySuncheon57922Republic of Korea

The saturation of the compacted bentonite buffer in the deep geological repository can cause bentonite swelling,intrusion into rock fractures,and ***,erosion and subsequent bentonite mass loss due to groundwater inflow can aggravate the overall integrity of the engineered barrier ***,the coupled hydro-mechanical interaction between the buffer and rock during groundwater inflow and bentonite intrusion should be evaluated to guarantee the long-term safety of deep geological *** study investigated the effect of bentonite erosion and intrusion on the elastic wave propagation characteristics in jointed rocks using a quasi-static resonant column *** rock specimens with different joint conditions(*** surface saturation and bentonite filling)were prepared using granite rock discs sampled from the Korea Underground Research Tunnel(KURT)and Gyeongju *** long-wavelength longitudinal and shear wave velocities were measured under different normal stress levels.A Hertzian-type power model was used to fit the wave velocities,and the relationship between the two fitted parameters provided the trend of joint *** simulations using three-dimensional distinct element code(3DEC)were conducted to better understand how the long-wavelength wave propagates through wet bentonite-filled rock joints.

关键词： Engineered barrier system Bentonite erosion and intrusion Jointed rock mass Long-wavelength elastic wave velocity Quasi-static resonant column test Three-dimensional distinct element code(3DEC)