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C/C复合材料Mo-Si-N抗氧化涂层的制备

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稀有金属材料与工程 2005年第11期34卷 1794-1797页

作者：来忠红朱景川全在昊尹钟大哈尔滨工业大学黑龙江哈尔滨150001 韩国机械研究院

在C/C复合材料表面采用熔浆法制备Mo-Si系涂层的烧结过程中通入氮气,开发了Si3N4-MoSi2/Si-SiC(Mo-Si-N系)多层抗氧化涂层,并初步考察了涂层的抗氧化性能.结果表明,多层涂层的致密性主要受制于起始氮化温度.只有在Si熔点以上通入氮气,... 详细信息

在C/C复合材料表面采用熔浆法制备Mo-Si系涂层的烧结过程中通入氮气,开发了Si3N4-MoSi2/Si-SiC(Mo-Si-N系)多层抗氧化涂层,并初步考察了涂层的抗氧化性能.结果表明,多层涂层的致密性主要受制于起始氮化温度.只有在Si熔点以上通入氮气,才能获得致密无缺陷的涂层.多层涂层的底层为SiC,外层为Si3N4,中间层为MoSi2/Si.这种多层涂层的抗氧化性能与涂层中MoSi2的含量有关;MoSi2含量为30%(体积分数,下同)和40%时,与真空中合成的Mo-Si涂层相比,高温抗氧化性能显著改善,抗氧化温度提高到1400℃～1450℃.

关键词： C/C复合材料:抗氧化涂层:Si3N4 MoSi2/Si SiC

Mixed-dimensional stacked nanocomposite structures for a specific wavelength-selectable ambipolar photoresponse

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Nano Research 2024年第6期17卷 5549-5558页

作者： Young Jae Park jaeho Shim Joo Song Lee Kyu Seung Lee Ji-Yeon Kim Kang Bok Ko Sang-Youp Yim Seongjun Kim Hoon-Kyu Shin Donghee Park Yong Ju Yun Dong Ick Son Institute of Advanced Composite Materials Korea Institute of Science and TechnologyJeollabuk-do 55324Republic of Korea National Institute for Nanomaterials Technology Pohang University of Science and TechnologyGyeongsangbuk-do 37673Republic of Korea Department of Semiconductor Science and Technology Semiconductor Physics Research CenterJeonbuk National UniversityJeonju 54896Republic of Korea Advanced Photonics Research Institute Gwangju Institute of Science and TechnologyGwangju 61005Republic of Korea Center for Opto-Electronic Materials and Devices Post-Silicon Semiconductor InstituteKorea Institute of Science and TechnologySeoul 02792Republic of Korea Graduate School of Energy and Environment(KU-KIST Green School) Korea UniversitySeoul 02841Republic of Korea KIST School Department of Nanomaterials and Nano ScienceUniversity of Science and Technology(UST)Daejeon 34113Republic of Korea

Mixed-dimensional composite structures using zero-dimensional(0D)quantum dots(QDs)and two-dimensional(2D)transition metal dichalcogenides(TMDs)materials are expected to attract great interest in optoelectronics due to the potential to generate new optical ***,we report on the unique optical characteristics of a devices with mixed dimensional vertically stacked structures based on tungsten diselenide(WSe_(2))/CdSeS QDs monolayer/molybdenum disulfide(MoS_(2))(2D/0D/2D).Specifically,it exhibits an ambipolar photoresponse characteristic,with a negative photoresponse observed in the 400-600 nm wavelength range and a positive photoresponse appeared at 700 nm *** resulted in the high negative responsivity of up to 52.22 mA·W^(−1)under 400 nm,which is 163 times higher than that of the photodetector without CdSeS *** also demonstrated the negative photoresponse,which could be due to increased carrier collision probability and non-radiative *** modeling and simulation reveal that Auger recombination among the types of non-radiative recombination is the main cause of negative photocurrent ***,we discovered ambipolar photoresponse near a specific wavelength corresponding to the energy of quantum *** study revealed interesting phenomenon in the mixed low-dimensional stacked structure and paved the way to exploit it for the development of innovative photodetection materials as well as for optoelectronic applications.

关键词： mixed-dimension quantum dot heterostructure photodetector ambipolar photoresponse

Femtosecond laser-mediated anchoring of polymer layers on the surface of a biodegradable metal

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Journal of Magnesium and Alloys 2021年第4期9卷 1380-1388页

作者： jaeho Park Bo-In Park Young Ju Son Sun Hee Lee Seung-Hoon Um Yu-Chan Kim Myoung-Ryul Ok jeong-Yun Sun Hyung-Seop Han Hojeong jeon Center for Biomaterials Korea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea Department of Materials science and Engineering Seoul National University(SNU)Seoul 08826Republic of Korea Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea Division of Bio-Medical Science and Technology KIST SchoolKorea University of Science and TechnologySeoul 02792Republic of Korea KU-KIST Graduate School of Converging Science and Technology Korea UniversitySeoul 02841Republic of Korea

Mg has received much attention as a next-generation implantable material owing to its biocompatibility,bone-like mechanical properties,and biodegradability in physiological *** application of various polymer coatings has been conducted in the past to reduce the rapid formation of hydrogen gas and the local change in pH during the initial phase of the chemical reaction with the body ***,we propose femtosecond(fs)laser-mediated Mg surface patterning for significant enhancement of the binding strength of the coating material,which eventually reduces the corrosion *** of the structural,physical,crystallographic,and chemical properties of the Mg surface have been conducted in order to understand the mechanism by which the surface adhesion increases between Mg and the polymer coating *** on the fs laser conditions,the surface structure becomes rough owing to the presence of several microscaled pits and grooves of nanoporous MgO,resulting in a tightly bonded poly(lactic-co-glycolic acid)(PLGA)*** corrosion rate of the PLGA-coated,fs laser-treated Mg is considerably slow compared with the non-treated Mg;the treated Mg is also more biocompatible compared with the non-treated *** fs laser-based surface modification technique offers a simple and quick method for introducing a rough coating on Mg;further,it does not require any chemical treatment,thereby overcoming a potential obstacle for its clinical use.

关键词： Femtosecond laser Biodegradable metal Polymer coating Surface modification Surface adhesion

Experimental study of bed-load transport using particle motion tracking

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International Journal of Sediment Research 2017年第1期32卷 73-81页

作者： jaeho Shim Jennifer G.Duan Department of Civil Engineering and Engineering Mechanics University of Arizona

A series of experiments were conducted in a flume to study bed-load *** motion of bed-load particles was captured by a series of images taken by a high-speed camera.A novelparticle motion tracking method was developed to automatically detect all the moving particles and calculate the instantaneous particle *** instantaneous bed load transport rate was calculated based on particle velocity and the volume of moving *** verify this method,bed load transport rate based on the image processing technique was compared to the manually measured ones as well as data from other *** showed that the new technique made it possible to quantify the spatial and temporal variations of bed load transport rate at the individual particle scale.

关键词： Bed-load transport Particle tracking Particle velocity

Improving hydroxyapatite coating ability on biodegradable metal through laser-induced hydrothermal coating in liquid precursor:Application in orthopedic implants

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Bioactive Materials 2023年第7期25卷 796-806页

作者： jaeho Park Seung-Hoon Um Youngmin Seo jaehong Lee Yu-Chan Kim Myoung-Ryul Ok Suk-Won Hwang jeong-Yun Sun Hyung-Seop Han Hojeong jeon Biomaterials Research Center Biomedical Research DivisionKorea Institute of Science and Technology(KIST)Seoul02792South Korea Department of Materials Science and Engineering Seoul National University(SNU)Seoul08826South Korea Division of Biomedical Science and Technology KIST SchoolKorea University of Science and TechnologySeoul02792South Korea KU-KIST Graduate School of Converging Science and Technology Korea UniversitySeoul02841South Korea

During the past decade,there has been extensive research toward the possibility of exploring magnesium and its alloys as biocompatible and biodegradable materials for implantable *** practical medical application,however,has been limited to specific areas owing to rapid corrosion in the initial stage and the consequent *** coatings can significantly reduce the initial corrosion of Mg alloys,and several studies have been carried out to improve the adhesion strength of the coating to the surfaces of the *** composition of hydroxyapatite(HAp)is very similar to that of bone tissue;it is one of the most commonly used coating materials for bone-related implants owing to favorable osseointegration *** this study,HAp was coated on Mg using nanosecond laser coating,combining the advantages of chemical and physical *** heat generated in the liquid precursor by the laser improved the adhesion of the coating through the precipitation and growth of HAp at the localized nanosecond laser focal area and increased the corrosion resistance and cell adhesion of *** physical,crystallographic,and chemical bondings were analyzed to explore the mechanism through which the surface adhesion between Mg and the HAp coating layer *** applicability of the coating to Mg screws used for clinical devices and improvement in its corrosion property were *** liquid environment-based laser surface coating technique offers a simple and quick process that does not require any chemical ligands,and therefore,overcomes a potential obstacle in its clinical use.

关键词： Biodegradable metal HAp coating Nanosecond laser Photothermal synthesis Soret effect(thermophoresis)

Efficient thermal management and all-season energy harvesting using adaptive radiative cooling and a thermoelectric power generator

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能源化学:英文版 2023年第9期84卷 496-501页

作者： Chanil Park Woohwa Lee Choyeon Park Sungmin Park jaeho Lee Yong Seok Kim Youngjae Yoo Advanced Materials Division Korea Research Institute of Chemical Technology(KRICT)Daejeon 34114Republic of Korea Department of Mechanical and Aerospace Engineering University of CaliforniaIrvineCA 92617United States Department of Advanced Materials Engineering Chung-Ang UniversityAnseong 17546Republic of Korea

Passive daytime radiative cooling(PDRC) is useful for thermal management because it allows an object to emit terrestrial heat into space without the use of additional *** produce sub-ambient temperatures under direct sunlight,PDRC materials are designed to reduce their absorption of solar energy and to enhance their long-wavelength infrared(LWIR) *** recent years,many photonic structures and polymer composites have been studied to improve the cooling system of ***,in cold weather(i.e. during winter in cold climates),buildings need to be kept warm rather than cooled due to heat *** overcome this limitation,temperature-responsive radiative cooling is a promising *** the present study,adaptive radiative cooling(ARC) film fabricated from a polydimethylsiloxane/hollow SiO_(2) microsphere/thermochromic pigment composite was *** found that the ARC film absorbed solar radiation under cold conditions while exhibiting radiative cooling at ambient temperatures above 40℃.Thus,in outdoor experiments,the ARC film achieved sub-ambient temperatures and had a theoretical cooling power of 63.2 W/m~2 in hot *** also demonstrated that radiative cooling with an energy harvesting system could be used to improve the energy management of buildings,with the thermoelectric module continuously generating output power using the ARC ***,we believe that our proposed ARC film can be employed for efficient thermal management of buildings and all-season energy harvesting in the near future.

关键词： Thermal management Daytime radiative cooling Temperature-adaptive film Thermoelectric device Energy harvesting

Synergistic stimulation of surface topography and biphasic electric current promotes muscle regeneration

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Bioactive Materials 2022年第5期7卷 118-129页

作者： Indong Jun Na Li Jaehee Shin jaeho Park Young Jun Kim Hojeong jeon Hyuk Choi Jae-Gu Cho Byoung Chan Choi Hyung-Seop Han Jae-Jun Song Environmental Safety Group Korea Institute of Science&Technology Europe(KIST-EUROPE)Saarbrücken66123Germany Department of Otorhinolaryngology-Head and Neck Surgery Korea University College of MedicineSeoul02841Republic of Korea Department of Medical Sciences Graduate School of MedicineKorea UniversitySeoul02841Republic of Korea Center for Biomaterials Biomedical Research InstituteKorea Institute of Science&Technology(KIST)Seoul02792Republic of Korea Laser Surface Texturing Group AYECLUSGyeonggi-do14255Republic of Korea

Developing a universal culture platform that manipulates cell fate is one of the most important tasks in the investigation of the role of the cellular *** study focuses on the application of topographical and electrical field stimuli to human myogenic precursor cell(hMPC)cultures to assess the influences of the adherent direction,proliferation,and differentiation,and induce preconditioning-induced therapeutic ***,a topographical surface of commercially available culture dishes was achieved by femtosecond laser *** detachable biphasic electrical current system was then applied to the hMPCs cultured on laser-textured culture ***-textured topographies were remarkably effective in inducing the assembly of hMPC myotubes by enhancing the orientation of adherent hMPCs compared with flat ***,electrical field stimulation through laser-textured topographies was found to promote the expression of myogenic regulatory factors compared with nonstimulated *** such,we successfully demonstrated that the combined stimulation of topographical and electrical cues could effectively enhance the myogenic maturation of hMPCs in a surface spatial and electrical field-dependent manner,thus providing the basis for therapeutic strategies.

关键词： Topography Electrical field stimulation Femtosecond laser Human myogenic precursor cell Cell therapy

A Near Optimal Power Allocation Scheme for Cooperative Relay Networking with NOMA

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China Communications 2019年第3期16卷 122-131页

作者： Haiyang Yu Wei Duan Guoan Zhang Yancheng Ji Xiaojun Zhu jaeho Choi The School of Electronics and Information Nantong University Division of Electronics and Information Engineering Chonbuk National University Department of ECE CAIIT Chonbuk National University

In this paper, we propose cooperative relay networks with non-orthogonal multiple access in order to design a near-optimal power allocation strategy. Like other next generation wireless technologies, spatially multiplexed transmissions are achieved by relay nodes which enables decode-and-forward relaying of a new superposition code after reception from the source. It is worth noting that, since it is hard to exactly prove the proposed PA scheme, due the fact that it is one kind of the approximate conjectures. Therefore, mathematical and numerical methods have been used to clarify the feasibility of the proposal. Numerical results indicate that it is able to asymptotically achieve the optimal sum rate at the higher signal-to-noise ratio region with the proposed strategy applied instead of negligible performance loss.

关键词： non-orthogonal multiple access cooperative multi-relay networks decode-and-forward two-stage power allocation

Improved Hybrid Beamforming for mmWave Multi-User Massive MIMO

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Computers, Materials & Continua 2021年第6期67卷 3057-3070页

作者： Ji-Sung Jung Won-Seok Lee Yeong-Rong Lee jaeho Kim Hyoung-Kyu Song Department of Information and Communication Engineering and Convergence Engineering for Intelligent Drone Sejong UniversitySeoul05006Korea Department of Electrical Engineering Sejong UniversitySeoul05006Korea

Massive multiple input multiple output(MIMO)has become essential for the increase of capacity as the millimeter-wave(mmWave)communication is ***,hybrid beamforming systems have been studied since full-digital beamforming is impractical due to high cost and power consumption of the radio frequency(RF)*** paper proposes a hybrid beamforming scheme to improve the spectral efciency for multi-user MIMO(MU-MIMO)*** a frequency selective fading environment,hybrid beamforming schemes suffer from performance degradation since the analog precoder performs the same precoding for all *** mitigate performance degradation,this paper uses the average channel covariance matrix for all subcarriers and considers an iterative algorithm to design analog precoder using approximation *** analog precoder is iteratively updated for each column until it *** proposed scheme can reduce errors in the approximating process of the overall spectral *** scheme can be applied to fully-connected and partially-connected *** simulation results show that spectral efciency performance for the proposed scheme is better than the conventional *** proposed scheme can achieve similar performance with full-digital beamforming by using a sufciently large number of RF ***,this paper shows that the proposed scheme outperforms other schemes in the frequency selective fading *** performance improvement can be achieved in both structures.

关键词： Hybrid precoding massive MIMO MU-MIMO mmwave frequency selective fading