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Liquid crystal between two distributed Bragg reflectors enables multispectral small-pitch spatial light modulator

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Light(Science & Applications) 2022年第8期11卷 1643-1645页

作者： Junghyun Park Kanghee Won young kim Advanced Sensor Lab Device Research CenterSamsung Advanced Institute of TechnologySuwonRepublic of Korea

The ability of controlling the phase of light at the subwavelength scale can be a game-changer due to its extraordinally wide angle-range in the wavefront shaping. By combining two conventional material and configurat... 详细信息

关键词： crystal enable light

Mechanical properties of high-strength concrete subjected to high temperature by stressed test

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中国有色金属学会会刊：英文版 2009年第B09期19卷 128-133页

作者： Gyu-Yong kim young-sun kim Tae-Gyu LEE Division of Architecture Engineering Chun gnam National University

Recently, the effects of high temperature on compressive strength and elastic modulus of high strength concrete were experimentally investigated. The present study is aimed to study the effect of elevated temperatures ranging from 20 ℃ to 700 ℃ on the material mechanical properties of high-strength concrete of 40, 60 and 80 MPa grade. During the strength test, the specimens are subjected to a 25% of ultimate compressive strength at room temperature and sustained during heating, and when the target temperature is reached, the specimens are loaded to failure. The tests were conducted at various temperatures (20-700 ℃) for concretes made with W/B ratios of 46%, 32% and 25%, respectively. The results show that the relative values of compressive strength and elastic modulus decrease with increasing compressive strength grade of specimen.

关键词：高强混凝土高温作用力学性能测试抗压强度温度升高弹性模量强度试验

Separation of primary solid phases from Al-Si alloy melts

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China Foundry 2014年第4期11卷 382-395页

作者： Ki young kim School of Energy Materials and Chemical EngineeringKorea University of Technology and EducationChungnam 330-708Korea

The iron-rich solids formed during solidification of Al-Si alloys which are known to be detrimental to the mechanical,physical and chemical properties of the alloys should be *** the other hand,Al-Si hypereutectic alloys are used to extract the pure primary silicon which is suitable for photovoltaic cells in the solvent refining *** of the important issues in iron removal and in solvent refining is the effective separation of the crystallized solids from the Al-Si alloy *** paper describes the separation methods of the primary solids from Al-Si alloy melts such as sedimentation,draining,filtration,electromagnetic separation and centrifugal separation,focused on the iron removal and on the separation of silicon in the solvent refining process.

关键词： separation Al-Si alloys primary solids iron removal silicon extraction

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

High-temperature Oxidation Behavior of Zircaloy-4 and Zirlo in Steam Ambient

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Journal of Materials Science & Technology 2010年第9期26卷 827-832页

作者： Hyung Hoon kim Jun Ho kim Jin young Moon Ho Seong Lee Jeong Joo kim young suck Chai School of Materials Science and Engineering Kyungpook National University School of Mechanical Engineering Yeungnam University214-1 Dae-dongGyeongsan-si

The oxidation characteristics for Zircaloy-4 and Zirlo in the temperature range of 700-1200°C under steam supply condition were investigated by using a modified thermo-gravimetric *** specimens were oxidized for 3600 s at each temperature and then quenched in a *** oxidation rate constants were measured from the weight gains to evaluate the oxidation behavior in Zircaloy-4 and *** weight gain rates of Zirlo were lower than those of Zircaloy-4,leading to the low rate *** different oxidation behaviors between both cladding materials were considered to be due to the difference in their chemical compositions.

关键词： Zircaloy-4 Zirlo Oxidation

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

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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World Journal of Gastroenterology 2014年第40期20卷 14581-14588页

作者： Hwi young kim Won kim Division of Gastroenterology and Hepatology Department of Internal Medicine Seoul Metropolitan Government-Seoul National University Boramae Medical Center Seoul 156-707 South Korea

Hepatitis B reactivation is a potentially serious complication of anticancer chemotherapy,which occurs during and after *** condition affects primarily hepatitis B surface antigen(HBsAg)-positive patients,but sometimes HBsAg-negative patients can be at risk,based only on evidence of past infection or occult infection with a low titer of detectable hepatitis B virus(HBV)*** clinical outcomes vary with the different degrees of virologic and biochemical rebound,ranging from asymptomatic elevations in liver enzymes to hepatic failure and even *** the remarkable advancement in the treatment of chronic hepatitis B over the past decade,proper strategies for the prevention and management of HBV reactivation remain ***,with the increasing use of rituximab in patients with lymphoma,HBV reactivation in occult or past infections has become increasingly problematic,especially in HBV-endemic *** review addresses the current knowledge on the clinical aspects and management of chemotherapy-related HBV reactivation,updates from recent reports,several unresolvedissues and future perspectives.

关键词： Hepatitis B virus Chemotherapy Reactivation

Biomimetic Quadruped Robot with a Spinal Joint and Optimal Spinal Motion via Reinforcement Learning

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Journal of Bionic Engineering 2021年第6期18卷 1280-1290页

作者： young Kook kim Woojin Seol Jihyuk Park LV R&D Team Electro-technology R&D CenterLS Electric Co.LtdCheongju28437Republic of Korea Digital Innovation Unit Korea Hydro&Nuclear Power Co.Ltd1312-gil YuseongdaeroYusung-guDaejeon34101Republic of Korea Department of Automotive Engineering College of Mechanical and IT EngineeringYeungnam University280 Daehak-roGyeongsanGyeongbuk38541Republic of Korea

Feline animals can run quickly using spinal joints as well as the joints that make up their four *** paper describes the development of a quadruped robot including a spinal joint that biomimics feline *** developed robot platform consists of four legs with a double 4-bar linkage type and one simplified rotary *** addition,Q-learning,a type of machine learning,was used to find the optimal motion profile of the spinal *** bounding gait was implemented on the robot system using the motion profile of the spinal joint,and it was confirmed that using the spinal joint can achieve a faster Center of Mass(CoM)forward speed than not using the spinal *** the motion profile obtained through Q-learning did not exactly match the spinal angle of a feline animal,which is more multiarticular than that of the developed robot,the tendency of the actual feline animal spinal motion profile,which is sinusoidal,was similar.

关键词： Quadruped robot system Bioinspired methods Legged robots Machine learning Q-learning