Ammonium Fluoride Mediated Synthesis of Anhydrous Metal Fluoride–Mesoporous Carbon Nanocomposites for High-Performance Lithium Ion Battery Cathodes

Chun, Jinyoung,Jo, Changshin,Sahgong, Sunhye,Kim, Min Gyu,Lim, Eunho,Kim, Dong Hyeon,Hwang, Jongkook,Kang, Eunae,Ryu, Keun Ah,Jung, Yoon Seok,Kim, Youngsik,Lee, Jinwoo American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.51

<P>Metal fluorides (MFx) are one of the most attractive cathode candidates for Li ion batteries (LIBs) due to their high conversion potentials with large capacities. However, only a limited number of synthetic methods, generally involving highly toxic or inaccessible reagents, currently exist, which has made it difficult to produce well-designed nanostructures suitable for cathodes; consequently, harnessing their potential cathodic properties has been a challenge. Herein, we report a new bottom-up synthetic method utilizing ammonium fluoride (NH4F) for the preparation of anhydrous MFx (CuF2, FeF3, and CoF2)/mesoporous carbon (MSU-F-C) nanocomposites, whereby a series of metal precursor nanoparticles preconfined in mesoporous carbon were readily converted to anhydrous MFx through simple heat treatment with NH4F under solventless conditions. We demonstrate the versatility, lower toxicity, and efficiency of this synthetic method and, using XRD analysis, propose a mechanism for the reaction. All MFx/MSU-F-C prepared in this study exhibited superior electrochemical performances, through conversion reactions, as the cathode for LIBs. In particular, FeF3/MSU-F-C maintained a capacity of 650 mAh g(FeF3)(-1) across 50 cycles, which is similar to 90% of its initial capacity. We expect that this facile synthesis method will trigger further research into the development of various nanostructured MFx for use in energy storage and other applications.</P>

Study of Rocker-Bogie typed Mobile Robot for Driving, Climbing and Standing Upright

Eunho Seo,Jooyoung Chun,Hunkeon Ko,Sangin Park,Dong Jin Hyun 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10

This paper studies a mobile platform system to provide a service for a large range of regions. The coverage of large service region is recently required while the service robot market is rapidly increased. Therefore, Regions of delivery/patrol/surveillance/inspection services started to include outdoor terrains as well as indoor environments. Therefore, mobile robots have to adapt uneven terrains and overcome obstacles. In this paper, we introduce a rocker-bogie typed mobile robot which is able to provide this required capability. The robot has six active driving wheels, two degrees of freedom (DoFs) for active steering, and 2 DoFs for active bogie. The linear dynamic model was derived, and practically the values for normal and traction forces are calculated through the simple pseudo-inverse technique. The compensation algorithm is added to achieve minimal friction on the bogie axis, which leads to all wheel contact with the ground through the adaptation to uneven terrains. Also, the calculated traction force is distributed to ground contact wheels based on sensor estimation. In the experiment, upright-standing and climbing a curb were demonstrated. Especially, the upright posture of the robot was verified to be controlled based on Linear Quadratic Regulator (LQR) optimization controller using inverted pendulum model.

Facile Synthesis of Nb₂O₅@Carbon Core–Shell Nanocrystals with Controlled Crystalline Structure for High-Power Anodes in Hybrid Supercapacitors

Lim, Eunho,Jo, Changshin,Kim, Haegyeom,Kim, Mok-Hwa,Mun, Yeongdong,Chun, Jinyoung,Ye, Youngjin,Hwang, Jongkook,Ha, Kyoung-Su,Roh, Kwang Chul,Kang, Kisuk,Yoon, Songhun,Lee, Jinwoo American Chemical Society 2015 ACS NANO Vol.9 No.7

<P>Hybrid supercapacitors (battery-supercapacitor hybrid devices, HSCs) deliver high energy within seconds (excellent rate capability) with stable cyclability. One of the key limitations in developing high-performance HSCs is imbalance in power capability between the sluggish Faradaic lithium-intercalation anode and rapid non-Faradaic capacitive cathode. To solve this problem, we synthesize Nb2O5@carbon core-shell nanocyrstals (Nb2O5@C NCs) as high-power anode materials with controlled crystalline phases (orthorhombic (7) and pseudohexagonal (TT)) via a facile one-pot synthesis method based on a water-in-oil microemulsion system. The synthesis of ideal T-Nb2O5 for fast Li+ diffusion is simply achieved by controlling the microemulsion parameter (e.g., pH control). The T-Nb2O5@C NCs shows a reversible specific capacity of similar to 180 mA h g(-1) at 0.05 A g(-1) (1.1-3.0 V vs Li/Li+) with rapid rate capability compared to that of TT-Nb2O5@C and carbon shell-free Nb2O5 NCs, mainly due to synergistic effects of (i) the structural merit of T-Nb2O5 and (ii) the conductive carbon shell for high electron mobility. The highest energy (similar to 63 W h kg(-1)) and power (16 528 W kg(-1) achieved at similar to 5 W h kg(-1)) densities within the voltage range of 1.0-35 V of the HSC using T-Nb2O5@C anode and MSP-20 cathode are remarkable.</P>

Rational design of Li₃VO₄@carbon core-shell nanoparticles as Li-ion hybrid supercapacitor anode materials

Lim, Eunho,Lim, Won-Gwang,Jo, Changshin,Chun, Jinyoung,Kim, Mok-Hwa,Roh, Kwang Chul,Lee, Jinwoo Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.39

<P>A Li-ion hybrid supercapacitor (Li-HSC) delivering high energy within seconds (excellent rate performance) with stable cycle life is one of the most highly attractive energy storage devices. However, the limited anode materials for Li-HSC systems lead to stagnation and restrict the development of high-performance Li-HSCs. To tackle this problem, a facile synthetic route to Li3VO4@carbon core-shell nanoparticles (Li3VO4@C NPs), a promising high-power anode for Li-HSCs, is reported. The synthesized Li3VO4@C NPs show a high specific capacity of ∼400 mA h g<SUP>−1</SUP> at the current density of 0.02 A g<SUP>−1</SUP> in the potential range from 0.2 to 3.0 V (<I>vs.</I> Li/Li<SUP>+</SUP>), with rapid charge/discharge characteristics (∼110 mA h g<SUP>−1</SUP> at 10 A g<SUP>−1</SUP>). By various electrochemical analyses, it was demonstrated that the excellent electrochemical properties of Li3VO4@C NPs stem from their improved pseudocapacitive behavior and their low internal resistance, which are mainly due to the synergistic effects of (i) a well-designed electrode morphology achieved by nano-engineering and (ii) the structural merits of a core-shell architecture. In addition, the Li-HSC using the Li3VO4@C NP anode and activated carbon (AC) cathode provides ∼190 W h kg<SUP>−1</SUP> energy and ∼18 500 W kg<SUP>−1</SUP> power density, with long-term cycle stability in the potential range from 0.0 to 4.3 V.</P>

Advanced Hybrid Supercapacitor Based on a Mesoporous Niobium Pentoxide/Carbon as High-Performance Anode

Lim, Eunho,Kim, Haegyeom,Jo, Changshin,Chun, Jinyoung,Ku, Kyojin,Kim, Seongseop,Lee, Hyung Ik,Nam, In-Sik,Yoon, Songhun,Kang, Kisuk,Lee, Jinwoo American Chemical Society 2014 ACS NANO Vol.8 No.9

<P>Recently, hybrid supercapacitors (HSCs), which combine the use of battery and supercapacitor, have been extensively studied in order to satisfy increasing demands for large energy density and high power capability in energy-storage devices. For this purpose, the requirement for anode materials that provide enhanced charge storage sites (high capacity) and accommodate fast charge transport (high rate capability) has increased. Herein, therefore, a preparation of nanocomposite as anode material is presented and an advanced HSC using it is thoroughly analyzed. The HSC comprises a mesoporous Nb<SUB>2</SUB>O<SUB>5</SUB>/carbon (m-Nb<SUB>2</SUB>O<SUB>5</SUB>–C) nanocomposite anode synthesized by a simple one-pot method using a block copolymer assisted self-assembly and commercial activated carbon (MSP-20) cathode under organic electrolyte. The m-Nb<SUB>2</SUB>O<SUB>5</SUB>–C anode provides high specific capacity with outstanding rate performance and cyclability, mainly stemming from its enhanced pseudocapacitive behavior through introduction of a carbon-coated mesostructure within a voltage range from 3.0 to 1.1 V (<I>vs</I> Li/Li<SUP>+</SUP>). The HSC using the m-Nb<SUB>2</SUB>O<SUB>5</SUB>–C anode and MSP-20 cathode exhibits excellent energy and power densities (74 W h kg<SUP>–1</SUP> and 18 510 W kg<SUP>–1</SUP>), with advanced cycle life (capacity retention: ∼90% at 1000 mA g<SUP>–1</SUP> after 1000 cycles) within potential range from 1.0 to 3.5 V. In particular, we note that the highest power density (18 510 W kg<SUP>–1</SUP>) of HSC is achieved at 15 W h kg<SUP>–1</SUP>, which is the highest level among similar HSC systems previously reported. With further study, the HSCs developed in this work could be a next-generation energy-storage device, bridging the performance gap between conventional batteries and supercapacitors.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-9/nn501972w/production/images/medium/nn-2014-01972w_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn501972w'>ACS Electronic Supporting Info</A></P>

Effects of red ginseng on gut, microbiota, and brain in a mouse model of post-infectious irritable bowel syndrome

Seonhye Yu,Eunho Chun,Yeounjung Ji,Young Joo Lee,Mirim Jin 고려인삼학회 2021 Journal of Ginseng Research Vol.45 No.6

Background: Irritable bowel syndrome (IBS), the most common functional gastrointestinal disorder, ischaracterized by chronic abdominal pain and bowel habit changes. Although diverse complicated etiologiesare involved in its pathogenesis, a dysregulated gutebrain axis may be an important factor. Redginseng (RG), a traditional herbal medicine, is proven to have anti-inflammatory effects and improvebrain function; however, these effects have not been investigated in IBS. Methods: Three-day intracolonic zymosan injections were used to induce post-infectious human IBS-likesymptoms in mice. The animals were randomized to receive either phosphate-buffered saline (CG) or RG(30/100/300 mg/kg) for 10 days. Amitriptyline and sulfasalazine were used as positive controls. Macroscopic scoring was performed on day 4. Visceral pain and anxiety-like behaviors were assessed bycolorectal distension and elevated plus maze and open field tests, respectively, on day 10. Nextgenerationsequencing of gut microbiota was performed, and biomarkers involved in gutebrain axisresponses were analyzed. Results: Compared to CG, RG significantly decreased the macroscopic score, frequency of visceral pain,and anxiety-like behavior in the IBS mice. These effects were comparable to those after sulfasalazine andamitriptyline treatments. Moreover, RG significantly increased the proliferation of beneficial microbes,including Lactobacillus johnsonii, Lactobacillus reuteri, and Parabacteroides goldsteinii. RG significantlysuppressed expression of IL-1b and c-fos in the gut and prefrontal cortex, respectively. Further, it restoredthe plasma levels of corticosterone to within the normal range, accompanied by an increase in adrenocorticotropichormone.

Administration of <i>Wasabia koreana</i> Ameliorates Irritable Bowel Syndrome-Like Symptoms in a Zymosan-Induced Mouse Model

Park, Bo-Kyung,Chun, Eunho,Choi, Jeong June,Shin, Younmin,Kho, Young Tak,Oh, Seung Hyun,Kim, Sun Yeou,Lee, Taek Hwan,Kim, Tae-Wan,Shin, Eunju,Do, Seon-Gil,Jin, Mirim Mary Ann Liebert, Inc. Publishers 2017 Journal of Medicinal Food Vol. No.

Mesoporous Ge/GeO₂/Carbon Lithium-Ion Battery Anodes with High Capacity and High Reversibility

Hwang, Jongkook,Jo, Changshin,Kim, Min Gyu,Chun, Jinyoung,Lim, Eunho,Kim, Seongseop,Jeong, Sanha,Kim, Youngsik,Lee, Jinwoo American Chemical Society 2015 ACS NANO Vol.9 No.5

<P>We report mesoporous composite materials (m-GeO<SUB>2</SUB>, m-GeO<SUB>2</SUB>/C, and m-Ge-GeO<SUB>2</SUB>/C) with large pore size which are synthesized by a simple block copolymer directed self-assembly. m-Ge/GeO<SUB>2</SUB>/C shows greatly enhanced Coulombic efficiency, high reversible capacity (1631 mA h g<SUP>–1</SUP>), and stable cycle life compared with the other mesoporous and bulk GeO<SUB>2</SUB> electrodes. m-Ge/GeO<SUB>2</SUB>/C exhibits one of the highest areal capacities (1.65 mA h cm<SUP>–2</SUP>) among previously reported Ge- and GeO<SUB>2</SUB>-based anodes. The superior electrochemical performance in m-Ge/GeO<SUB>2</SUB>/C arises from the highly improved kinetics of conversion reaction due to the synergistic effects of the mesoporous structures and the conductive carbon and metallic Ge.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2015/ancac3.2015.9.issue-5/acsnano.5b00817/production/images/medium/nn-2015-008173_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn5b00817'>ACS Electronic Supporting Info</A></P>

귀 자극요법 적용이 중년 여성 근로자의 요통에 미치는 효과

박경숙(Park Kyungsook),하은호(Ha Eunho),김유나(Kim Yuna),권수진(Kwon Soojin),류이정(Ru Leejung),송주현(Song Juhyun),우영화(Woo Youngwha),이재연(Lee Jaeyeon),전인희(Chun Inhee),강현경(Kang Hyunkyung),박희정(Park Heejung),이은주(Lee Eunjo 대한근관절건강학회 2010 근관절건강학회지 Vol.17 No.1

Purpose: The purpose of this study was to investigate the effect of ear reflexotherapy on back pain of working women in middle age. Methods: The quasi-experimental, nonequivalent control group pretest-posttest design was used for the study. Total of 56 participants composed of experimental group (n=26) and control group (n=30), who were working in four hospitals in urban area. The degree of back pain after ear reflexotherapy was measured by VAS. The data were analyzed by frequency, percent, t-test and χ²-test. Results: The degree of back pain after ear reflexotherapy in the experimental group was significantly reduced, while there was no difference in control group. There was a significant difference between the experimental group and control group in the degree of back pain after ear reflexotherapy (t=3.702, p=.001). Conclusion: Application of ear reflexotherapy was effective for employed women in middle age and it needs to be further evaluated among the other population.