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Nano Research 2014年第5期7卷 717-730页

作者： Dohyuk yoo Jeonghun Kim jung hyun Kim Department of Chemical and Biomolecular Engineering Yonsei University 50 Yonsei-ro Seodaemun-gu Seou1120-749 Republic of Korea Electronic Materials Division R&D Center Dongjin Semichem Co. Ltd. 625-3 Yodang-Ri Yanggam-Myeon Hwaseong-Gun Gyeonggi-Do Republic of Korea

We report for the first time highly conductive poly（3,4-ethylenedioxythiophene）： poly（4-styrenesulfonate）（PEDOT：PSS）/graphene composites fabricated by in situ polymerization and their applications in a thermoelectric device and a platinum （Pt）-free dye-sensitized solar cell （DSSC） as energy harvesting systems. Graphene was dispersed in a solution of poly（4-styrenesulfonate）（PSS） and polymerization was directly carried out by addition of 3,4-ethylenedioxythiophene （EDOT） monomer to the dispersion. The content of the graphene was varied and optimized to give the highest electrical conductivity. The composite solution was ready to use without any reduction process because reduced graphene oxide was used. The fabricated film had a conductivity of 637 ***-1, corresponding to an enhancement of 41%, after the introduction of 3 wt.% graphene without any further complicated reduction processes of graphene being required. The highly conductive composite films were employed in an organic thermoelectric device, and the device showed a power factor of 45.7 μW·m^-1K^-2 which is 93% higher than a device based on pristine PEDOT：PSS. In addition, the highly conductive composite films were used in Pt-free DSSCs, showing an energy conversion efficiency of 5.4%, which is 21% higher than that of a DSSC based on PEDOT：PSS.

关键词： direct synthesis conductive polymer graphene composite thermoelectric material dye-sensitized solar cell

Oxidative coupling of methane over LaAlO3 perovskite catalysts prepared by a co-precipitation method: Effect of co-precipitation pH value

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Journal of Energy Chemistry 2019年第8期28卷 1-8,I0001页

作者： Yujin Sim Jihoon yoo Jeong-Myeong Ha Ji Chul jung Department of Chemical Engineering Myongji UniversityYongin 17058 Republic of Korea Clean Energy Research Center Korea Institute of Science and TechnologySeoul 02792 Republic of Korea

Oxidative coupling of methane(OCM) was conducted over LaAlO3X catalysts that were prepared by a coprecipitation method using different co-precipitation pH values(X = 6–10). The aim is to investigate the effect of p H values on the catalytic activity of La AlO3 catalysts in this reaction. The results showed that the co-precipitation pH value affected greatly on the formation of chemical species of precipitate precursors in the co-precipitation step, leading to different phases of the finally obtained LaAlO3 *** the co-precipitation pH value increased up to 8, the lanthanum-related phases such as La2 O3 and La(OH)3 were gradually formed as by-products, preventing the formation of LaAlO3 perovskite crystalline structure and facilitating the formation of oxygen vacancies on catalyst surface. However, at pH value of9 or higher, the lanthanum content in the precipitate precursor was increased greatly. Not LaAlO3 perovskite but lanthanum-related phases were developed as main phases, reducing their catalytic activities in this reaction. Among LaAlO3 catalysts, the one prepared at pH = 8 showed the highest C2 yield due to its well-developed oxygen vacancies and electrophilic lattice oxygen. Therefore, the co-precipitation pH value strongly affected the LaAlO3 catalyst activity in OCM reaction. A precious pH control should be required to prepare various perovskite catalysts for the OCM.

关键词： LaAlO3 Perovskite Oxidative coupling of methane Co-precipitation pH value

Slip-enhanced Reverse Electrodialytic Power Generation in Ion-selective Nanochannels

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Journal of Thermal Science 2013年第1期22卷 36-41页

作者： Byeongdong Kang Jaisuk yoo hyun jung Kim Dong-Kwon Kim Department of Mechanical Engineering Ajou University

Power generation by reverse electrodialysis in ion-selective nanochannels is numerically investigated. Especially,in the present study, the influence of hydrodynamic slip at the surface of nanochannels is investigated. The current-potential characteristics of the nanochannels are calculated by solving several governing equations:Nernst-Planck equation for the ionic concentrations, the Poisson equation for the electric potential, and the Navier-Stokes equation for the diffusioosmotic flow. hydrodynamic slip is applied as the boundary condition at the surface of nanochannels. As the slip length increases, the diffusioosmotic flow velocity and electrical conductance of ions increase because the friction at the surface of nanochannels decreases. It is shown that the power generation is enhanced by 44% with a moderate 100nm slip length by using a nanochannel with 10nm height.

关键词： Reverse electrodialysis Ion-selective nanochannel Power generation Slip length

Self‑Powered Airflow Sensor Based on Energy Harvesting of Ventilation Air in Buildings

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Advanced Fiber Materials 2023年第5期5卷 1788-1798页

作者： Moon hyun Chung Seunghwan yoo Woo‑Nam jung Hakgeun Jeong Kyung‑Hwa yoo Department of Physics Yonsei University50 Yonsei‑RoSeodaemun‑GuSeoul 03722Republic of Korea Energy ICT Convergence Research Department Energy Efficiency Research DivisionKorea Institute of Energy Research152 Gajeong‑RoYuseong‑GuDaejeon 34129Republic of Korea Advanced Combustion Power Lab Energy Efficiency Research DivisionKorea Institute of Energy Research152Gajeong‑RoYuseong‑GuDaejeon 34129Republic of Korea Department of Mechanical Engineering Korea Advanced Institute of Science and Technology(KAIST)291 Daehak‑RoYuseongDaejeon 34141Republic of Korea

Heating,ventilation,and air conditioning(HVAC)systems account for one-third of the total energy consumption in office *** use of airflow measurements to control the operation of HVAC systems can reduce energy consumption;thus,a sensor capable of monitoring airflow in a duct system is *** nanogenerators(TENGs)can be utilized as self-powered sensors in airflow-driven TENGs(ATENGs)as self-powered *** employing ferroelectric materials and surface modifications,the surface charges of TENGs can be *** this study,fibrous-mat TENGs were prepared using ferroelectric materials consisting of poly(vinylidene fluoride-co-trifluoroethylene)(PVDF-TrFE)and polyamide 11(nylon-11).And these materials were subsequently ***(3,4-ethylenedioxythiophene):poly(styrenesulfonate)was added to PVDF-TrFE to enhance the ferroelectric crystalline phase.X-ray diffraction analysis revealed that this incorporation affects theβ*** addition,the surface of nylon-11 was modified using the electrospray technique for post-treatment,thereby improving the interfacial adhesion between the *** materials were then utilized in fibrous-mat ATENGs(FM-ATENGs)to demonstrate their practical *** FM-ATENGs can be effectively used in an Arduino airflowcheck sensor,showcasing their potential for application in HVAC systems,to enhance airflow control and energy efficiency.

关键词： HVAC Airflow-driven triboelectric nanogenerator Building energy harvesting Fibrous mat Airflow sensor

Flow Visualization and Performance Measurements of a Flagellar Propeller

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Journal of Bionic Engineering 2012年第3期9卷 322-329页

作者： hyejin Jeon yoon-Cheol Kim Dongwook Yim jung Yui yoo Songwan Jin School of Mechanical and Aerospace Engineering Seoul National University Seoul 151-744 Korea Department of Mechanical Engineering Korea Polytechnic University Siheung-si Gyeonggi-do 429-793 Korea

A new type of propeller that is optimized for low Reynolds numbers is required to propel a small object in a medium where the flow is dominated by viscous rather than inertial forces. A propeller in the shape of a bacterial flagellum seems an appro- priate choice for driving a small object. Accordingly, in this study, we visualized the velocity field induced by a spring-like propeller inspired by the Escherichia coli flagellum, using a macroscopic model and applying stereoscopic particle image velocimetry. We also experimentally evaluated the effect of pitch and rotational speed on the performance of this flagellar propeller. Silicone oil, which has a kinematic viscosity 100,000 times that of water, was used as the working fluid to generate a low Reynolds number for the macroscopic model. Thrust, torque, and velocity were measured as functions of pitch and rota- tional speed, and the efficiency of the propeller was calculated from the measured results. We found that the flagellar propeller reached a max!mum efficiency when the pitch angle was approximately 53°. Compared to pitch, rotational speed had a relatively small effect on the efficiency, and the pitch altered the flow pattern behind the rotating propeller.

关键词： flagellar propeller stereoscopic PIV bacterial flagellum small swimming object

Work up for the clopidogrel hypersensitivity that led to recognising the undi- agnosed myelodysplastic syndrome

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Journal of Geriatric Cardiology 2016年第3期13卷 274-276页

作者： yoo Sang Baek jung Woo Lee Jiehyun Jeon Department of Dermatology College of Medicine Korea University Seoul South Korea

Antiplatelet therapy with clopidogrel is widely used as a preventive strategy in patients with acute coronary syn- drome, particularly after stent *** mani- festations of clopidogrel hypersensitivity reaction have been reported including cutaneous,and hematologic symp- toms[31 as well as fatal reactions including thrombotic throm- bocytopenic purpura （TTP）.

关键词： Clopidogrel hypersensitivity Myelodysplastic syndrome

The interplay between direct-acting antivirals and hepatocellular carcinoma in chronic hepatitis C

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Hepatoma Research 2020年第3期6卷 15-23页

作者： Sun Hong yoo jung hyun Kwon Department of Internal Medicine Catholic University Liver Research CenterThe Catholic University of KoreaSeoul 06591Korea

Direct-acting antivirals(DAAs)have been introduced for the treatment of hepatitis C virus,and the sustained virological response rate after DAAs was reported to be over 95%.Because of the high sustained virological response rate,the risk of hepatocellular carcinoma(HCC)was expected to be ***,an unexpected high risk of HCC recurrence after DAA treatment was reported,and thus the dispute about the association of DAA and HCC *** present article reviews the interplay between DAAs and HCC.

关键词： Chronic hepatitis C hepatocellular carcinoma direct-acting antivirals

Dual function of a high-contrast hydrophobic-hydrophilic coating for enhanced stability of perovskite solar cells in extremely humid environments

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Nano Research 2017年第11期10卷 3885-3895页

作者： Jin Sun yoo Gill Sang Han Seongha Lee Min Cheol Kim Mansoo Choi hyun Suk jung jung-Kun Lee School of Advanced Materials Science amp Engineering Sungkyunkwan University Suwon 440-746 Republic of Korea Department of Mechanical Engineering and Materials Science University of Pittsburgh Pittsburgh Pennsylvania 15261 USA Department of Mechanical and Aerospace Engineering Seoul National University Seoul 08826 Republic of Korea

In spite of a continuous increase in their power conversion efficiency （PCE） and an economically viable fabrication process,organic-inorganic perovskite solar cells （PSCs） pose a significant problem when used in practical applications：They show fast degradation of the PCE when exposed to very humid *** this study,the stability of PSCs under very humid conditions is greatly enhanced by coating the surface of the PSC devices with a multi-layer film consisting of ultrahydrophobic and relatively hydrophilic layers.A hydrophobic composite of poly（methyl methacrylate）（PMMA）,polyurethane （PU）,and SiO2 nanoparticles successfully retards the water molecules from very humid ***,the hydrophilic layer with moderately PMMA captures the residual moisture within the perovskite layer;subsequently,the perovskite layer *** dual function of the coating film keeps the PCE of PSCs at 17.3% for 180 min when exposed to over 95% humidity.

关键词： perovskite solar cell stability surface coating ultrahydrophobic self-recovery

Experiences of Counselors Who Provided Psychological Support during COVID-19 Disaster: A Qualitative Study

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International Journal of Mental Health Promotion 2023年第5期25卷 687-697页

作者： jung Eun Kim So Yeon yoo Namgu Mental Health Welfare Center Daegu42424South Korea Department of Nursing Kyungil UniversityGyeongbuk38428South Korea

Background:In crisis intervention sites such as infectious disease disasters,counselors are repeatedly exposed,directly or indirectly,to the traumatic experiences of *** counseling has a negative effect on coun-selors,which can eventually interfere with the counseling process for disaster ***,exploring and understanding the experiences of counselors is necessary to ensure that qualitative counseling for disaster victims can be continuously and efficiently ***:This study investigated the experiences of counselors who participated in mental health counseling as psychological support for victims of the COVID-19 disaster in ***:This is a qualitative ***:The study participants comprised 18 counselors who had mental health professional qualifications of level 2 or higher and who had provided mental health counseling for COVID-19 confirmed cases and quarantined ***:Data were collected using focus group interviews from February 21 to May 29,*** duration of each interview was 60–90 min,and the data were analyzed using content ***:Thefinal theme was“Continuing to walk this road anytime,anywhere.”The par-ticipants’experiences were identified in four sub-themes:“being deployed to unprepared counseling,”“encoun-tering various difficulties,”“feeling full of meaning and value,”and“hoping to become a better counselor.”Conclusions:In order to continuously provide qualitative counseling in case of an infectious disease disaster such as COVID-19,it is important to develop a qualification and competency strengthening program through educa-tion and training to secure the crisis intervention expertise of counselors according to the characteristics of the *** addition,a psychological support manual for each disaster should be prepared at the national level according to the type of disaster.

关键词： Psychological support experience counselor COVID-19 qualitative research

pH-induced structural changes of surface immobilized poly (L-lysine) by two-dimensional (2D) infrared correlation study

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Chinese Chemical Letters 2015年第2期26卷 173-176页

作者： Eun Joo yoo Boknam Chae Young Mee jung Seung Woo Lee School of Chemical Engineering Yeungnam University Pohang Accelerator Laboratory Department of Chemistry Kangwon National University

This paper reports the pH-induced structural changes in the surface immobilized poly（L-lysine）（PLL）***-dimensional（2D） correlation analysis was applied to the Fourier transform infrared（FTIR）spectra of the surface-immobilized PLL film to examine the spectral changes induced by the alternations of the protonation state of the amino group in the side *** spectral changes in the FTIR spectra of the PLL film were observed between pH 7 and *** decrease in the protonation state of the amino group in the side chain induced spectral changes in the amino group as well as conformational changes in the alky]group in the side *** pH 1-8,the spectral changes in the amino and alkyl groups in the side chain occurred before those of the amide group in the main chain of the surface immobilized PLL film.

关键词： Poly(L-lysine)(PLL) Surface-immobilized polypeptide FT-IR spectroscopy 2D correlation spectroscopy