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Frontiers of Environmental Science & Engineering 2024年第7期18卷 73-85页

作者： Sanggwon An Sangsoo Choi hyeong rae kim Jungho Hwang School of Mechanical Engineering Yonsei UniversitySeoul 02876Republic of Korea Gas Metrology Group Korea Research Institute of Standards and Science(KRISS)Daejeon 34113Republic of Korea

The World Health Organization has raised concerns about the possibility of airborne transmission in enclosed and poorly ventilated ***,rapid monitoring of airborne viruses is necessary in multi-use facilities with dense ***,an electrostatic air sampler(250 L/min)was developed in this work to obtain indoor viral aerosol samples for analysis via the Polymerase Chain Reaction(PCR).Aerosol tests with H1N1 and HCoV-229E were performed to evaluate the sample collection *** analysis,along with another aerosol test,was conducted to evaluate the recovery of the virus particles collected by the *** laboratory tests,our electrostatic sampler obtained viral samples that were detectable by PCR under the simulated viral pandemic scenario(3000 RNA copies per cubic meter of air)within 40 *** resulting cycle threshold(C)values were 35.07 and 37.1 for H1N1 and HCoV-229E,*** the performance evaluation in the laboratory,field tests were conducted in a university classroom from October 28 to December 2,*** A and HCoV-229E were detected in two air samples,and the corresponding C,values were 35.3 and *** PCR results are similar to those obtained from laboratory tests,considering the simulatedviralpandemic scenario.

关键词： Airborne virus Electrostatic sampler Rapid monitoring Indoor environment Field test

Ag-GST/HfO_(x)-based unidirectional threshold switching selector with low leakage current and threshold voltage distribution for high-density cross-point arrays

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Rare Metals 2024年第1期43卷 280-288页

作者： Kyoung-Joung Yoo Dae-Yun Kang Nahyun kim Ho-Jin Lee Ta-hyeong kim Taeho kim Tae Geun kim School of Electrical Engineering Korea UniversitySeoul 02841Republic of Korea

The use of electrochemical-metallization-based volatile threshold switching selectors in cross-point arrays has been widely explored owing to their high on-off ratios and simple ***,these devices are unsuitable for cross-point architectures because of the difficulty in controlling the random filament formation that results in large fluctuations in the threshold voltage during *** this study,we investigated the unidirectional threshold transition characteristics associated with an Ag/GST/HfO_(x)/Pt-based bilayer selector and demonstrated the occurrence of a low leakage current(<1×10^(-11) A) and low distribution of the threshold voltage(Δ0.11 V).The bilayer structure could control the filament formation in the intermediate state through the insertion of an HfO_(x) tunneling *** stacking a bilayer selector with NiO_(x)based resistive random-access memory,the leakage and programming currents of the device could be significantly *** the crossbar array configuration,we performed equivalent circuit analysis of a one-selector oneresistor(1S1R) devices and estimated the optimal array size to demonstrate the applicability of the proposed *** maximum acceptable crossbar array size of the 1S1R device with the Ag/GST/HfO_(x)/Pt/Ti/NiO_(x)/Pt structure was 5.29×10^(14)(N^(2),N=2.3×10^(7)).

关键词： Selector device Tunneling barrier Threshold switching Sputtering 1S1R Cross-point array

Depolarization mitigated in ferroelectric Hf_(0.5)Zr_(0.5)O_(2)ultrathin films(<5 nm)on Si substrate by interface engineering

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Journal of Advanced Ceramics 2024年第3期13卷 282-292页

作者： Se Hyun kim Younghwan Lee Dong Hyun Lee Geun hyeong Park Hyun Woo Jeong Kun Yang Yong Hyeon Cho Young Yong kim Min Hyuk Park Department of Materials Science and Engineering College of EngineeringSeoul National UniversitySeoul 08826Republic of Korea Research Institute of Advanced Materials College of EngineeringSeoul National UniversitySeoul 08826Republic of Korea Inter-university Semiconductor Research Center College of EngineeringSeoul National UniversitySeoul 08826Republic of Korea Pohang Accelerator Laboratory Pohang University of Science&TechnologyPohang 790784Republic of Korea

(Hf,Zr)O_(2)offers considerable potential for next-generation semiconductor devices owing to its nonvolatile spontaneous polarization at the ***,scaling this material to sub-5 nm thickness poses several challenges,including the formation of an interfacial layer and high trap *** particular,a low-k SiO_(2)interfacial layer is naturally formed when(Hf,Zr)O_(2)films are directly grown on a Si substrate,leading to high depolarization fields and rapid reduction of the remanent *** address these issues,we conducted a study to significantly improve ferroelectricity and switching endurance of(Hf,Zr)O_(2)films with sub-5 nm thicknesses by inserting a TiO_(2)interfacial *** deposition of a Ti film prior to Hf_(0.5)Zr_(0.5)O_(2)film deposition resulted in a high-k TiO_(2)interfacial layer and prevented the direct contact of Hf_(0.5)Zr_(0.5)O_(2)with *** findings show that the high-k TiO_(2)interfacial layer can reduce the SiO_(2)/Si interface trap density and the depolarization field,resulting in a switchable polarization of 60.2μC/cm^(2)for a 5 nm thick Hf_(0.5)Zr_(0.5)O_(2)***,we propose that inserting a high-k TiO_(2)interfacial layer between the Hf_(0.5)Zr_(0.5)O_(2)film and the Si substrate may offer a promising solution to enhancing the ferroelectricity and reliability of(Hf,Zr)O_(2)grown on the Si substrate and can pave the way for next-generation semiconductor devices with improved performance.

关键词： ferroelectric charge trapping hafnia depolarization

Organic X-Ray Image Sensors Using a Medium Bandgap Polymer Donor with Low Dark Current

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ENERGY & ENVIRONMENTAL MATERIALS 2024年第6期7卷 230-237页

作者： Ha, Jong-Woon Eom, Seung Hun Cha, Bo Kyung Song, Seyeong Eun, hyeong Ju kim, Jong H. Park, Jong Mok kim, Bongsoo Park, Byoungwook Ko, Seo-Jin Yoon, Sung Cheol Lee, Changjin Jung, In Hwan Hwang, Do-Hoon Pusan Natl Univ Chem Inst Funct Mat Dept Chem Busan 46241 South Korea Korea Res Inst Chem Technol KRICT Div Adv Energy Mat Res Ctr Daejeon 34114 South Korea Korea Electrotechnol Res Inst KERI Electromed Device Res Ctr Ansan 15588 South Korea Ulsan Natl Inst Sci & Technol UNIST Grad Sch Carbon Neutral Sch Energy & Chem Engn Ulsan 44919 South Korea Ajou Univ Dept Mol Sci & Technol Suwon 16449 South Korea Korea Res Inst Chem Technol Res Ctr Adv Specialty Chem Ulsan 44412 South Korea Ulsan Natl Inst Sci & Technol UNIST Dept Chem Ulsan 44919 South Korea Hanyang Univ Dept Organ & Nano Engn Human Tech Convergence Program 222 Wangsimni Ro Seoul 04763 South Korea

The development of portable X-ray detectors is necessary for diagnosing fractures in unconscious patients in emergency situations. However, this is quite challenging because of the heavy weight of the scintillator and silicon photodetectors. The weight and thickness of X-ray detectors can be reduced by replacing the silicon layer with an organic photodetectors. This study presents a novel bithienopyrroledione-based polymer donor that exhibits excellent photodetection properties even in a thick photoactive layer (similar to 700 nm), owing to the symmetric backbone and highly soluble molecular structure of bithienopyrroledione. The ability of bithienopyrroledione-based polymer donor to strongly suppress the dark current density (J(d) similar to 10(-10) A cm(-2)) at a negative bias (-2.0 V) while maintaining high responsivity (R = 0.29 A W-1) even at a thickness of 700 nm results in a maximum shot-noise-limited specific detectivity of D-sh* = 2.18 x 10(13) Jones in the organic photodetectors. Printed organic photodetectors are developed by slot-die coating for use in X-ray detectors, which exhibit D-sh* = 2.73 x 10(12) Jones with clear rising (0.26 s) and falling (0.29 s) response times upon X-ray irradiation. Detection reliability is also proven by linear response of the X-ray detector, and the X-ray detection limit is 3 mA.

关键词： low dark current low detection limit organic photodetector printable X-ray DETECTORS PHOTOCONDUCTORS SENSITIVITY

Catalpa bignonioides extract improves exercise performance through regulation of growth and metabolism in skeletal muscles

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Asian Pacific Journal of Tropical Biomedicine 2024年第2期14卷 47-54页

作者： Hoibin Jeong Dong-joo Lee Sung-Pil Kwon SeonJu Park Song-rae kim Seung Hyun kim Jae-Il Park Deug-chan Lee Kyung-Min Choi WonWoo Lee Ji-Won Park Bohyun Yun Su-Hyeon Cho Kil-Nam kim Seoul Center Korea Basic Science InstituteSeoul 02841Republic of Korea Chuncheon Center Korea Basic Science InstituteChuncheon 24341Republic of Korea Research&Development Center Chungdam CDC JNPharm LLC.Chuncheon 24341Republic of Korea Department of Biomedical Technology Kangwon National UniversityChuncheon 24341Republic of Korea Yonsei Institute of Pharmaceutical Sciences College of PharmacyYonsei UniversityIncheon 21983Republic of Korea Gwangju Center Korea Basic Science InstituteGwangju 61751Republic of Korea Honam National Institute of Biological Resources 99Gohadoan-gilMokpo-siJeollanam-do58762Republic of Korea Department of Bio-analysis Science University of Science&TechnologyDaejeon34113Republic of Korea

Objective:To evaluate the effects of Catalpa bignonioides fruit extract on the promotion of muscle growth and muscular capacity in vitro and in ***:Cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide *** proliferation was assessed using a 5-bromo-2’-deoxyuridine(BrdU)assay *** blot analysis was performed to determine the protein expressions of related *** effects of Catalpa bignonioides extract were investigated in mice using the treadmill exhaustion test and whole-limb grip strength *** composition analysis was performed using high-performance liquid chromatography(HPLC).Results:Catalpa bignonioides extract increased the proliferation of C2C12 mouse myoblasts by activating the Akt/mTOR signaling *** also induced metabolic changes,increasing the number of mitochondria and glucose metabolism by phosphorylating adenosine monophosphate-activated protein *** an in vivo study,the extract-treated mice showed improved motor abilities,such as muscular endurance and grip ***,HPLC analysis showed that vanillic acid may be the main component of the Catalpa bignonioides extract that enhanced muscle ***:Catalpa bignonioides improves exercise performance through regulation of growth and metabolism in skeletal muscles,suggesting its potential as an effective natural agent for improving muscular strength.

关键词： Catalpa bignonioides Skeletal muscle Cell proliferation Mitochondria Energy metabolism C2C12

Chemodynamics of heavy metals in long-term contaminated soils:Metal speciation in soil solution

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Journal of Environmental Sciences 2009年第11期21卷 1532-1540页

作者： Kwon-rae kim Gary Owens Centre for Environmental Risk Assessment and Remediation University of South Australia Climate Change & Agroecology Division Department of Agricultural Environment National Academy of Agricultural Science

The concentration and speciation of heavy metals in soil solution isolated from long-term contaminated soils were investigated. The soil solution was extracted at 70% maximum water holding capacity （MWHC） after equilibration for 24 h. The free metal concentrations （Cd^2＋, Cu^2＋, Pb^2＋, and Zn^2＋） in soil solution were determined using the Donnan membrane technique （DMT）. Initially the DMT was validated using artificial solutions where the percentage of free metal ions were significantly correlated with the percentages predicted using MINTEQA2. However, there was a significant difference between the absolute free ion concentrations predicted by MINTEQA2 and the values determined by the DMT. This was due to the significant metal adsorption onto the cation exchange membrane used in the DMT with 20%, 28%, 44%, and 8% mass loss of the initial total concentration of Cd, Cu, Pb, and Zn in solution, respectively. This could result in a significant error in the determination of free metal ions when using DMT if no allowance for membrane cation adsorption was made. Relative to the total soluble metal concentrations the amounts of free Cd^2＋（3%-52%） and Zn^2＋（11%-72%） in soil solutions were generally higher than those of Cu^2＋（0.2%-30%） and Pb^2＋（0.6%-10%）. Among the key soil solution properties, dissolved heavy metal concentrations were the most significant factor governing free metal ion concentrations. Soil solution pH showed only a weak relationship with free metal ion partitioning coefficients （Kp） and dissolved organic carbon did not show any significant influence on Kp.

关键词： Donnan membrane technique free metal ion heavy metals partitioning coefficient solubility speciation

k-Nearest Neighbor Query Processing Algorithms for a Query Region in Road Networks

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Journal of Computer Science & Technology 2013年第4期28卷 585-596页

作者： hyeong-Il kim Jae-Woo Chang Department of Computer Engineering Chonbuk National University Cloud Open R&D Center Chonbuk National University

Recent development of wireless communication technologies and the popularity of smart phones .are making location-based services （LBS） popular. However, requesting queries to LBS servers with users＇ exact locations may threat the privacy of users. Therefore, there have been many researches on generating a cloaked query region for user privacy protection. Consequently, an efficient query processing algorithm for a query region is required. So, in this paper, we propose k-nearest neighbor query （k-NN） processing algorithms for a query region in road networks. To efficiently retrieve k-NN points of interest （POIs）, we make use of the Island index. We also propose a method that generates an adaptive Island index to improve the query processing performance and storage usage. Finally, we show by our performance analysis that our k-NN query processing algorithms outperform the existing k-Range Nearest Neighbor （kRNN） algorithm in terms of network expansion cost and query processing time.

关键词： island index k-nearest neighbor query processing scheme locatiombased service road network

Simple black holes with anisotropic fluid

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Chinese Physics C 2019年第2期43卷 125-131页

作者： Inyong Cho hyeong-Chan kim School of Liberal Arts Seoul National University of Science and Technology School of Liberal Arts and Sciences Korea National University of Transportation

We study a spherically symmetric spacetime made of an anisotropic fluid whose radial equation-of-state is given by p_1=-ρ. This case allows analytic solutions and is a good example for studying the static configuration of a black hole plus matter. For a given equation-of-state parameter w_2 = p_2/ρ for angular directions, we find the exact solutions of the Einstein equation described by two parameters. We classify the solutions into six types based on the behavior of the metric function. Depending on the parameters, the solutions can have event and cosmological horizons. One of the solution types corresponds to a generalization of the Reissner-Nordstr(o|¨)m black hole, the thermodynamic properties for which are obtained in a simple form. The solutions are stable under radial perturbations.

关键词： black hole exact solution general relativity

Influence of Indian mustard (Brassica juncea) on rhizosphere soil solution chemistry in long-term contaminated soils:A rhizobox study

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Journal of Environmental Sciences 2010年第1期22卷 98-105页

作者： Kwon-rae kim Gary Owens Soon-lK Kwon Climate Change & Agroecology Division Department of Agricultural EnvironmentNational Academy of Agricultural ScienceRDARepublic of Korea Centre for Environmental Risk Assessment and Remediation University of South Australia

This study investigated the influence of Indian mustard （Brassicajuncea） root exudation on soil solution properties （pH, dissolved organic carbon （DOC）, metal solubility） in the rhizosphere using a rhizobox. Measurement was conducted following the cultivation of Indian mustard in the rhizobox filled four different types of heavy metal contaminated soils （two alkaline soils and two acidic soils）. The growth of Indian mustard resulted in a significant increase （by 0.6 pH units） in rhizosphere soil solution pH of acidic soils and only a slight increase （〈 0.1 pH units） in alkaline soils. Furthermore, the DOC concentration increased by 17-156 mg/L in the rhizosphere regardless of soil type and the extent of contamination, demonstrating the exudation of DOC from root. Ion chromatographic determination showed a marked increase in the total dissolved organic acids （OAs） in rhizosphere. While root exudates were observed in all soils, the amount of DOC and OAs in soil solution varied considerably amongst different soils, resulting in significant changes to soil solution metals in the rhizosphere. For example, the soil solution Cd, Cu, Pb, and Zn concentrations increased in the rhizosphere of alkaline soils compared to bulk soil following plant cultivation. In contrast, the soluble concentrations of Cd, Pb, and Zn in acidic soils decreased in rhizosphere soil when compared to bulk soils. Besides the influence of pH and DOC on metal solubility, the increase of heavy metal concentration having high stability constant such as Cu and Pb resulted in a release of Cd and Zn from solid phase to liquid phase.

关键词： dissolved organic carbon heavy metals root exudates solubility rhizosphere chemistry

Benefits of Stochastic Optimization for Scheduling Energy Storage in Wholesale Electricity Markets

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Journal of Modern Power Systems and Clean Energy 2021年第1期9卷 181-189页

作者： hyeong Jun kim Ramteen Sioshansi Antonio J.Conejo the Department of Integrated Systems Engineering The Ohio State UniversityColumbusOhioUSA the Department of Electrical and Computer Engineering The Ohio State UniversityColumbus.OhioUSA

We propose a two-stage stochastic model for optimizing the operation of energy storage. The model captures two important features: uncertain real-time prices when day-ahead operational commitments are made;and the price impact of charging and discharging energy storage. We demonstrate that if energy storage has full flexibility to make real-time adjustments to its day-ahead commitment and market prices do not respond to charging and discharging decisions, there is no value in using a stochastic modeling framework, i.e., the value of stochastic solution is always zero. This is because in such a case the energy storage behaves purely as a financial arbitrageur day ahead, which can be captured using a deterministic *** show also that prices responding to its operation can make it profitable for energy storage to "waste" energy, for instance by charging and discharging simultaneously, which is normally sub-optimal. We demonstrate our model and how to calibrate the price-response functions from historical data with a practical case study.

关键词： Energy storage stochastic optimization value of stochastic solution electricity market