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H_2S Sensing characteristics of Thin Film SnO_2 Sensor with N_2 Treatment

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稀有金属材料与工程 2006年第A3期35卷 385-388页

作者： Jong-Won Kim Kwang-Hyun Yun geon-young cha Gi-Hong Rue Duk-Dong Lee Jeung-Soo Huh Department of Nano-Science and Technology Sangyuk-Dong 1370Bukgu DaeguKorea Department of Materials Science and Metallurgy Sangyuk-Dong 1370Bukgu DaeguKorea School of Electronic Engineering Kyungpook National UniversitySangyuk-Dong 1370Bukgu DaeguKorea Department of Nano-Science and Technology Department of Materials Science and MetallurgySangyuk-Dong 1370Bukgu DaeguKorea

SnO_2 thin film sensors were fabricated by a thermal evaporation *** sensors were heated for thermal *** high porosity,SnO_2 thin film sensors were treated in a N_2 *** sensors that were treated with O_2 after being treated with N_2 showed 70 % sensitivity for 1×10~ -6) of H_2S,which is higher than the sensors that were only treated with O_*** Ni metal,as a catalyst,was evaporated on the thin film Sn on the Al_2O_3 *** sensor was heated to grow the Sn nanowire in a tube furnace with N_2 *** nanowire was heated for *** sensitivity of SnO_2 nanowire sensor was measured for 500×10~ -9) of H_*** selectivity of the SnO_2 nanowire sensor was compared with the thin film and the thick film SnO_*** sensor was measured for H_2S,CO,and NH_3 in this study.

关键词： SnO2 gas sensor N2 nanowire H2S

Enhancing the efficiency and scalability of perovskite solar cells through pseudo-halide salt addition

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Journal of Materials Science & Technology 2023年第34期165卷 161-169页

作者： Dohun Baek geon Yeong Park Jeongbeom cha Hyemi Na Dong Seok Ham Min Kim School of Chemical Engineering Future Energy Research CenterJeonbuk National UniversityJeonju 54896Republic of Korea Graduate School of Integrated Energy-AI Jeonbuk National UniversityJeonju 54896Republic of Korea Chemical Materials Solutions Center Korea Research Institute of Chemical Technology(KRICT)Daejeon 34114Republic of Korea

Organic-inorganic halide perovskites have significant potential for application in next-generation solar ***,their applications are limited by challenges associated with large-area processability and long-term stability owing to the presence of pinholes and defect ***,we incorporated cesium formate in a perovskite active layer using a sequential perovskite fabrication process to eliminate the defect sites of perovskites and improve the film processability via roll-to-roll(R2R)*** addition of cesium formate salt to the PbI2 layer influences the perovskite crystal formation behavior as well as increases the perovskite crystallinity and decreases the defect ***,cesium formate addition eliminated small PbI2 grains and smoothed the perovskite surface,resulting in a large crystal grain *** formate ions interact with the PbI2 component and passivate halide vacancy defects,reducing nonradiative recombination and improving charge ***,the treated perovskite films were highly stable in air,exhibiting improved efficiency retention over time and achieving a power conversion efficiency(PCE)of>22%compared to the ***,the additive-treated perovskite film was processed using the R2R method,achieving a high PCE of>14%with minimal hysteresis.

关键词： Perovskite Solar Cells Pseudo-halide ion Stability Roll-to-roll process

Active control of highway bridges subject to a variety of earthquake loads

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Earthquake Engineering and Engineering Vibration 2015年第2期14卷 253-263页

作者： Ryan Mitchell young-Jin cha Yeesock Kim Aniket Anil Mahajan Department of Civil and Environmental Engineering Worcester Polytechnic Institute (WPI) Worcester MA 01609-2280 USAGraduate Research Assistant Department of Civil Engineering University of Manitoba Winnipeg MB R3L5V6 Canada Assistant Professor Department of Civil and Environmental Engineering Worcester Polytechnic Institute (WPI) Worcester MA 01609-2280 USA Department of Civil and Environmental Engineering Worcester Polytechnic Institute (WPI) Worcester MA 01609-2280 USA Graduate Research Assistant

In this paper, a wavelet-fi ltered genetic-neuro-fuzzy(WGNF) control system design framework for response control of a highway bridge under various earthquake loads is discussed. The WGNF controller is developed by combining fuzzy logic, discrete wavelet transform, genetic algorithms, and neural networks for use as a control algorithm. To evaluate the performance of the WGNF algorithm, it is tested on a highway bridge equipped with hydraulic actuators. It controls the actuators installed on the abutments of the highway bridge structure. Various earthquakes used as input signals include an artifi cial earthquake, the El-Centro, Kobe, North Palm Springs, Turkey Bolu, Chi-Chi, and Northridge earthquakes. It is proved that the WGNF control system is effective in mitigating the vibration of the highway bridge under a variety of seismic excitation.

关键词： structural control wavelet transform genetic algor

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)

Recent Advances in Organ Specific Wireless Bioelectronic Devices:Perspective on Biotelemetry and Power Transfer Using Antenna Systems

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Engineering 2022年第4期8卷 27-41页

作者： Ahsan Noor Khan young-Ok cha Henry Giddens Yang Hao School of Electronic Engineering and Computer Science Queen Mary University of LondonLondon E14NSUK

The integration of electronics and biology has spawned bioelectronics and opened exciting opportunities to fulfill the unmet needs of therapeutic *** developments in nanoelectronics and soft and biocompatible materials have shown potential applicability to clinical practices,including physiological sensing,drug delivery,cardiovascular monitoring,and brain *** date,most bioelectronic devices require wired connections for electrical control,making their implantation complicated and inconvenient for *** an alternative,wireless technology is proliferating to create bioelectronics that offer noninvasive control,biotelemetry,and wireless power transfer(WPT).This review paper provides a comprehensive overview of wireless bioelectronics and ongoing developments in their applications for organ-specific treatments,including disorders and *** main emphasis is on delineating the key features of antennas,namely their radiation characteristics,materials,integration with rest of the electronics,and experimental *** the recent progress in wireless mediated bioelectronics is expected to enhance the control of its functionalities,there are still numerous challenges that need to be addressed for commercialization,as well as to address everexpanding and evolving future therapeutic targets.

关键词： Bioelectronics Neural implants Drug delivery Antennas Wireless power

Size-dependent transition of the deformation behavior of Au nanowires

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Nano Research 2015年第3期8卷 941-947页

作者： Na-young Park Ho-Seok Nam PiI-Ryung cha Seung-Cheol Lee School of Advanced Materials Engineering Kookmin University Seou1136-702 R. O. Korea Future Convergence Research Division Korea Institute of Science and Technology (KIST) Seou1136-791 R. O. Korea Indo-Korea Science and Technology Center Korea Institute of Science and Technology (KIST) Seou1136-791 R. O. Korea

Inspired by the controversy over tensile deformation modes of single-crystalline 〈110〉/{111} Au nanowires, we investigated the dependency of the deformation mode on diameters of nanowires using the molecular dynamics technique. A new criterion for assessing the preferred deformation mode-slip or twin propagation--of nanowires as a function of nanowire diameter is presented. The results demonstrate the size-dependent transition, from superplastic deformation mediated by twin propagation to the rupture by localized slips in deformed region as the nanowire diameter decreases. Moreover, the criterion was successfully applied to explain the superplastic deformation of Cu nanowires.

关键词： Au nanowire molecular dynamics size-dependent transition tensile deformationmechanism

Effects of Initial and Boundary Conditions on Heavy Rainfall Simulation over the Yellow Sea and the Korean Peninsula:Comparison of ECMWF and NCEP Analysis Data Effects and Verification with Dropsonde Observation

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Advances in Atmospheric Sciences 2024年第9期41卷 1787-1803页

作者： Jiwon HWANG Dong-Hyun cha Donghyuck YOON Tae-young GOO Sueng-Pil JUNG Department of Civil Urban Earth and Environmental Engineering Ulsan National Institute of Science and TechnologyUlsan 44919South Korea Program in Atmospheric and Oceanic Sciences Princeton UniversityPrincetonNew Jersey 08544USA National Institute of Meteorological Sciences NIMSJeju 63568South Korea

This study evaluated the simulation performance of mesoscale convective system(MCS)-induced precipitation,focusing on three selected cases that originated from the Yellow Sea and propagated toward the Korean *** evaluation was conducted for the European Centre for Medium-Range Weather Forecasts(ECMWF)and National Centers for Environmental Prediction(NCEP)analysis data,as well as the simulation result using them as initial and lateral boundary conditions for the Weather Research and Forecasting ***,temperature and humidity profiles from 3D dropsonde observations from the National Center for Meteorological Science of the Korea Meteorological Administration served as validation *** showed that the ECMWF analysis consistently had smaller errors compared to the NCEP analysis,which exhibited a cold and dry bias in the lower levels below 850 *** model,in terms of the precipitation simulations,particularly for high-intensity precipitation over the Yellow Sea,demonstrated higher accuracy when applying ECMWF analysis data as the initial *** advantage also positively influenced the simulation of rainfall events on the Korean Peninsula by reasonably inducing convective-favorable thermodynamic features(i.e.,warm and humid lower-level atmosphere)over the Yellow *** conclusion,this study provides specific information about two global analysis datasets and their impacts on MCS-induced heavy rainfall simulation by employing dropsonde observation ***,it suggests the need to enhance the initial field for MCS-induced heavy rainfall simulation and the applicability of assimilating dropsonde data for this purpose in the future.

关键词： initial conditions dropsonde heavy rainfall forecast global model analysis evaluation

Ankle and toe weakness caused by calcified ligamentum flavum cyst: A case report

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World Journal of Clinical Cases 2023年第35期11卷 8392-8398页

作者： Ho-young Jung geon-U Kim Yong-Won Joh Jun-Seok Lee Department of Orthopedic Surgery Eunpyeong St.Mary’s HospitalCollege of MedicineThe Catholic University of KoreaSeoul 03312South Korea

BACKGROUND Ligamentum flavum cysts,which are most common in mobile junctional levels of the spine,can be a rare cause of spinal *** have been several case reports of ligamentum flavum ***,there is yet to be a documented case report of a calcified ligamentum flavum ***,we report the first case of a calcified ligamentum flavum cyst causing ankle and toe *** SUMMARY A 66-year-old male visited our hospital complaining of claudication as well as thigh and calf pain in his left leg,all beginning two weeks *** examination revealed motor weakness of the left ankle dorsiflexion and great toe *** spinal computed tomography scans showed spinal stenosis combined with a calcified mass at the left side of the L4-5 *** reso-nance imaging showed dural sac compression caused by the calcified mass at the left ligamentum flavum of the L4-5 *** performed decompressive laminectomy and excision of the calcified mass combined with posterior lumbar interbody fusion at the L4-5 ***-operatively,we found a firm and nodule like mass originating from the ventral surface of ligamentum *** examination suggested a calcified pseudocyst without a capsular *** the operation,the patient’s motor weakness in the ankle and great toe improved *** The patient’s ankle and great toe weakness were improved successfully after surgical removal of the calcified cyst.

关键词： Ligamentum flavum Calcified cyst Spinal stenosis Claudication Motor weakness Spine Case report

Comparison of the Bright Band characteristics Measured by Micro Rain Radar (MRR) at a Mountain and a Coastal Site in South Korea

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Advances in Atmospheric Sciences 2009年第2期26卷 211-221页

作者： Joo-Wan cha Ki-Ho chaNG Seong Soo YUM young-Jean CHOI Department of Atmospheric Sciences Yonsei University Global Environment System Research Laboratory NIMR/KMA

Data from a long term measurement of Micro Rain Radar （MRR） at a mountain site （Daegwallyeong, DG, one year period of 2005） and a coastal site （Haenam, HN, three years 2004-2006） in South Korea were analyzed to compare the MRR measured bright band characteristics of stratiform precipitation at the two sites. On average, the bright band was somewhat thicker and the sharpness （average gradient of reflectivity above and below the reflectivity peak） was slightly weaker at DG, compared to those values at HN. The peak reflectivity itself was twice as strong and the relative location of the peak reflectivity within the bright band was higher at HN than at DG. Importantly, the variability of these values was much larger at HN than at DG. The key parameter to cause these differences is suggested to be the difference of the snow particle densities at the two sites, which is related to the degree of riming. Therefore, it is speculated that the cloud microphysical processes at HN may have varied significantly from un-rimed snow growth, producing low density snow particles, to the riming of higher density particles, while snow particle growth at DG was more consistently affected by the riming process, and therefore high density snow particles. Forced uplifting of cloudy air over the mountain area around DG might have resulted in an orographic supercooling effect that led to the enhanced riming of supercooled cloud drops.

关键词： Micro Rain Radar bright band thickness and sharpness cloud microphysical processes local characteristics