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Improved Hybrid Precoding Technique with Low-Resolution for MIMO-OFDM System

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Computers, Materials & Continua 2021年第8期68卷 2205-2220页

作者： Seulgi Lee Ji-Sung jung Young-Hwan You Hyoung-Kyu song Department of Information and Communication Engineering and Convergence for Intelligent DroneSejong UniversitySeoul05006Korea Department of Computer Engineering Sejong UniversitySeoul05006Korea

This paper proposes an improved hybrid beamforming system based on multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM)*** proposed beamforming system improves energy efficiency compared to the conventional hybrid beamforming *** sub-connected and full-connected structure are considered to apply the proposed *** the conventional hybrid beamforming,the usage of radio frequency(RF)chains and phase shifter(PS)gives high power and hardware *** this paper,the phase over sampling(POS)with switches(SW)is used in hybrid beamforming system to improve the energy *** POS-SW structure samples the value of analog beamformer to make lower resolution than conventional *** number of output data in POS is decided by the resolution of POS *** limited number of POS decides the resolution of antenna array and the values of POSs are designed from maximum and minimum phase angle antenna *** efficiency without the phase shifter is high although channel capacity is nearly similar with conventional ***,the amplifier with POS-SW system is proposed to improve the BER *** to the data bits,the output signals of POS are *** system with 2,3 and 4 bits is simulated to prove the proposed *** order to overcome the loss of low-resolution system,the amplifier with POS-SW system using channel information is *** average sum-rate of 4 bits system shows the similar performance with the conventional hybrid beamforming *** structure can play an important role by increasing the energy efficiency of the wireless communication system that many antennas are *** is shown that the BER,average sum rate and energy efficiency of the proposed scheme are more improved than the conventional hybrid beamforming system.

关键词： Hybrid beamforming MIMO-OFDM system analog precoding POS-SW

Infiltration by monocytes of the central nervous system and its role in multiple sclerosis: reflections on therapeutic strategies

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Neural Regeneration Research 2025年第3期20卷 779-793页

作者： Guangyong Zhang Qing Yao Chubing Long Pengcheng Yi Jiali song Luojia Wu Wei Wan Xiuqin Rao Yue Lin Gen Wei Jun Ying Fuzhou Hua Department of Anesthesiology the Second Affiliated Hospital of Nanchang UniversityNanchangJiangxi ProvinceChina Key Laboratory of Anesthesiology of Jiangxi Province NanchangJiangxi ProvinceChina

Mononuclear macrophage infiltration in the central nervous system is a prominent feature of neuroinflammation. Recent studies on the pathogenesis and progression of multiple sclerosis have highlighted the multiple roles of mononuclear macrophages in the neuroinflammatory process. Monocytes play a significant role in neuroinflammation, and managing neuroinflammation by manipulating peripheral monocytes stands out as an effective strategy for the treatment of multiple sclerosis, leading to improved patient outcomes. This review outlines the steps involved in the entry of myeloid monocytes into the central nervous system that are targets for effective intervention: the activation of bone marrow hematopoiesis, migration of monocytes in the blood, and penetration of the blood–brain barrier by monocytes. Finally, we summarize the different monocyte subpopulations and their effects on the central nervous system based on phenotypic differences. As activated microglia resemble monocyte-derived macrophages, it is important to accurately identify the role of monocyte-derived macrophages in disease. Depending on the roles played by monocyte-derived macrophages at different stages of the disease, several of these processes can be interrupted to limit neuroinflammation and improve patient prognosis. Here, we discuss possible strategies to target monocytes in neurological diseases, focusing on three key aspects of monocyte infiltration into the central nervous system, to provide new ideas for the treatment of neurodegenerative diseases.

关键词： blood–brain barrier macrophages monocytes multiple sclerosis neuroinflammation review therapy

Certain Fixed Point Theorems and Application to the Fractal Space

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Communications in Mathematical Research 2015年第2期31卷 180-192页

作者： Ji You-qing Ri song-il School of Mathematics Jilin University Department of Mathematics University of Science

In this paper, we present some important generalizations of the Banach contraction principle, in which the Lipschitz constant k is replaced by some real- valued control function. For the applications to the fractal sp... 详细信息

关键词： fixed point generalized contraction Hausdorff distance fractal topo-logical equivalence

Deduction of a meteorological phenology indicator from reconstructed MODIS LST imagery

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Journal of Forestry Research 2020年第6期31卷 2205-2216页

作者： Chi Hong Lim song Hie jung Nam Shin Kim Chang Seok Lee Department of Bio and Environmnetal Technology Graduate SchoolSeoul Women’s UniversitySeoul Republic of Korea Research Team on Ecological and Natural Map National Institute of EcologySeocheon Choongnam Republic of Korea Department of Bio and Environmnetal Technology Seoul Women’s UniversitySeoul Republic of Korea

Phenology is a valuable attribute of vegetation to assess the biological impacts from climate change.A challenge of phenological research is to obtain information on both high temporal resolution and fine spatial scale ***,we constructed an air temperature map based on temporal merging and spatial interpolation algorithms to overcome the cloud-related problem from the MODIS LST ***,we derived the accumulated growing degree days(AGDD)from the constructed mean air temperature map to use as a meteorological ***,we verified the indicator with the seasonal mean air temperature and the green-up date of a Quercus mongolica forest determined from the field-based *** AGDD threshold for each *** forest when the first leaf has unfolded was detected from the EXG trajectory extracted from digital camera images.A comparison between meteorological and MODIS-derived AGDD showed good agreement between *** was also high consistency between DoYs extracted from AGDD and EVI based on curvature K for *** forests of 30 sampling sites throughout South *** results prove that microclimatic factors such as elevation,waterbody,and land-use intensity were faithfully reflected in the reconstructed ***,the results of this study could be applied effectively in areas where microclimatic variation is very severe and for monitoring phenology of undergrowth,which is difficult to detect from reflectance imaging.

关键词： Climate change Digital camera Growing degree days MODIS Phenology Quercus mongolica

Effects of irradiation on superconducting properties of small-grained MgB_(2) thin films

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Chinese Physics B 2023年第12期32卷 534-540页

作者：刘丽 jung Min Lee Yoonseok Han Jaegu song Chorong Kim Jaekwon Suk Won Nam Kang 刘杰 Soon-Gil jung Tuson Park Center for Quantum Materials and Superconductivity(CQMS) Sungkyunkwan UniversitySuwon 16419Republic of Korea Department of Physics Sungkyunkwan UniversitySuwon 16419Republic of Korea Institute of Modern Physics Chinese Academy of Sciences(CAS)Lanzhou 730000China School of Nuclear Science and Technology University of Chinese Academy of Sciences(UCAS)Beijing 100049China Korea Multi-purpose Accelerator Complex Korea Atomic Energy Research InstituteGyeongjuGyeongbuk 38180Republic of Korea Department of Physics Education Sunchon National UniversitySuncheon 57922Republic of Korea

We investigate the effect of ion irradiation on MgB_(2) thin films with small grains of approximately 122 nm and 140 *** flux pinning by grain boundaries is insignificant in the pristine MgB_(2) films due to good inter-grain connectivity,but is significantly improved after 120-keV Mn-ion *** scaling behavior of the flux pinning force density for the ion-irradiated MgB_(2) thin films with nanoscale grains demonstrates the predominance of pinning by grain boundaries,in contrast to the single-crystalline MgB_(2) films where normal point pinning was dominant after low-energy ion *** results suggest that irradiation-induced defects can accumulate near the grain boundaries in metallic MgB_(2) superconductors.

关键词： MgB_(2)films grain boundaries flux pinning low-energy ion irradiation

2.47 GPa grade ultra-strong 15Co-12Ni secondary hardening steel with superior ductility and fracture toughness

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Journal of Materials Science & Technology 2021年第7期66卷 36-45页

作者： Young-Kyun Kim Kyu-Sik Kim Young-Beum song jung Hyo Park Kee-Ahn Lee Department of Materials Science and Engineering Inha UniversityIncheon22212Republic of Korea Agency for Defense Development(ADD) Yuseong-guDaegeon34186Republic of Korea

This study investigated the effect of multi-step heat treatment on the microstructure, mechanical properties and fracture behavior of thick 15 Co-12 Ni secondary hardening steel. As-quenched sample was found to have elongated prior austenite grain(PAG) and coarse lenticular martensitic structure. On the other hand, heat-treated sample was observed to have fine lenticular martensitic structure due to fine PAG size and a lot of nano-sized carbides. Also, after heat treatment, nano-scale reverted austenite film was formed at the martensite interfaces. The heat-treated sample showed 2.47 GPa superior tensile strength and superior elongation of about 12 %. The high strength was mainly due to fine block size and high number density of nano-sized carbides. The average value of plane strain fracture toughness(KIC) was 29.3 MPa m1/2, which indicated a good fracture toughness even with the high tensile strength. The tensile fracture surface was observed to have ductile fracture mode(cup-and-cone) and the formation of about ~1 μm ultra-fine dimples. In addition to this, nano-sized carbides were observed within the *** findings suggested that the nano-sized carbide had a positive effect not only on the strength but also on the ductility of the alloy. The fractured surface after toughness test, also showed ductile fracture mode with a lot of dimples. Based on the above results, correlation among microstructural evolution,deformation and fracture mechanisms along the heat-treatment was also discussed.

关键词： Ultra-high strength High Co-Ni secondary hardening steel Microstructure Tensile properties Fracture toughness Reverted austenite

Intelligent reflecting surface for sum rate enhancement in MIMO systems

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Digital Communications and Networks 2024年第1期10卷 94-100页

作者： Chan-Yeob Park Ji-Sung jung Yeong-Rong Lee Beom-Sik Shin Hyoung-Kyu song Department of Information and Communication Engineering Sejong UniversitySeoulGwangjin-guGunja-dong 98Republic of Korea Department of Convergence Engineering for Intelligent Drone Sejong University SeoulGwangjin-guGunja-dong 98Republic of Korea

The research for the Intelligent Reflecting Surface(IRS)which has the advantages of cost and energy efficiency has been *** capacity can be effectively increased by appropriately setting the phase value of IRS elements according to the channel ***,the problem of obtaining an appropriate phase value of IRs is difficult to solve due to the non-convex *** paper proposes an iterative algorithm for the alternating optimal solution in the Single User Multiple-Input-Multiple-Output(SU-MIMO)*** proposed iterative algorithm finds an alternating optimal solution that is the phase value of IRS one by *** results show that the proposed method has better performance than that of the randomized IRS *** number of iterations for maximizing the performance of the proposed algorithm depends on the channel state between the IRS and the receiver.

关键词： Intelligent reflecting surface MIMO Sum rate

Formation of FeMo_2B_2 phase in boron containing 9Cr-1.5Mo ferritic steels

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Rare Metals 2006年第z2期25卷 213-219页

作者： jung Woo-Sang HONG Suk-Woo song Sang-Min SOOK-In Kwun CHUNG Soon-Hyo Materials Science & Technology Division Korea Institute of Science & Technology Seoul 136-791 Korea Department of Materials Science and Engineering Korea University Seoul 136-713 Korea

The segregation and diffusion of boron during heat treatments were studied. The influence of boron contents, aging time and applied stress on FeMo2B2 formation was also studied. Finally, the effects of boron contents and FeMo2B2 formation on the high temperature strength were studied. Boron atoms were segregated to prior austenite grain boundary during normalizing treatment. And these boron atoms were slowly diffused into the grain interior during tempering and aging at 700 ℃. The FeMo2B2 phase was only formed after 1,000 h aging at 700 ℃ in alloy containing 196 ppm boron. The formation of FeMo2B2 phase is accelerated by the applied stress. It was expected that the formation of FeMo2B2 is closely related to the redistribution of boron atoms. The tensile strengths at 700 ℃ are increased with the increase of boron contents. However, the formation of FeMo2B2 phase results in lower tensile strength.

关键词： 9Cr-1.5Mo ferritic steels precipitation behavior boron effect FeMo2B2 phase tensile strength

Adaptive Relay Selection Scheme for Minimization of the Transmission Time

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Computers, Materials & Continua 2021年第10期69卷 1361-1373页

作者： Yu-Jin Na Ji-Sung jung Young-Hwan You Hyoung-Kyu song Department of Information and Communication Engineering and Convergence for Intelligent DroneSejong UniversitySeoul05006Korea Department of Computer Engineering and Convergence for Intelligent DroneSejong UniversitySeoul05006Korea

As the installation of small cells increases,the use of relay also *** relay operates as a base station as well as just an *** the roles and types of relays become more diverse,appropriate relay selection technology is an effective way to improve communication *** researches for relay selection have been studied to secure the reliability of relay *** this paper,the relay selection scheme is proposed for a cooperative system using decode-and-forward(DF)relaying scheme in the mobile communication *** maintain the transmission rate,the proposed scheme classifies a candidate group considering the outage probability of multiple *** the applicable candidate group,the proposed scheme selects the relay considering the amount of data allocated to each ***,the proposed scheme defines the unit transmission time through each user’s data and relay ***,the proposed scheme selects a relay that minimizes the total transmission time through the relay transmission time that calculates the unit transmission time for all *** this adaptive relay selection scheme,an optimal relay can be assigned for each *** the same transmission rate and the amount of data,the proposed scheme improves the performance of transmission time and *** results show that the proposed scheme reduces the total transmission time for the same amount of data and signal to noise ratio(SNR).

关键词： Relay selection cooperative relay MIMO outage probability transmission time