[DGIST Weekly Article] 고재원·엄지원 교수팀, 뇌질환 완치에 한 걸음 다가서다

http://hdl.handle.net/20.500.11750/9238

Authors  Han, Kyung Ah; Ko, Ji Seung; Pramanik, Gopal; Kim, Jin Young; Tabuchi, Katsuhiko; Um, Ji Won; Ko, Jaewon

Citation  Journal of Neuroscience, 38(30), 6700-6721

Abstract

URI  http://hdl.handle.net/20.500.11750/9222

Authors  Oh, Keonyoung; Stanley, Christopher J.; Damiano, Diane L.; Kim, Jonghyun; Yoon, Jungwon; Park, Hyung-Soon

Citation  Gait and Posture, 65, 157-162

Abstract

Background:Patients with brain injuries such as Parkinson's disease or stroke exhibitabnormal gait characteristics especially during gait transitions such as stepinitiation and turning. Since such transitions could precipitate falls andresultant injuries, evaluation and rehabilitation of non-steady state gait inthose patients are important. Whereas body weight supported treadmill training(BWSTT) provides a safe and controlled environment for gait training, it isunable to adequately train for gait transitions since the typical lineartreadmill does not allow for changes in walking direction and naturalfluctuations in speed. Research question: This paper verifies if the suggestedvirtual reality (VR) based walking interface combined with the unidirectional treadmillcan stimulate the user to initiate turning gait. Methods: To validate whetherinitiation of turning was successfully achieved with the proposed walkingsystem, we developed the VR-based walking interface combined with theself-paced treadmill and compared kinematics, kinetics, and muscle activationlevels during the VR-based turning and overground (OG) turning as well asbetween straight walking and turning within conditions. Results: Despitewalking on a linear treadmill, subjects showed significant increases in headrotation, pelvic rotation, right hip abduction, left hip adduction, footprogression, medial-lateral ground reaction forces, right medial hamstringactivation level, and changes in step width during the VR turn compared tostraight walking. Significance: The developed VR-based turning interface canprovide a safe and controlled environment for assessment of turning in healthycontrols and may have a potential for assessment and training in patients withneurological disorders. © 2018 Elsevier B.V.

http://hdl.handle.net/20.500.11750/9229

Authors  Kim, Jung Sik; Kim, Dae-Hwan; Hwang, Dae Kue

Citation  Journal of Power Sources, 400, 9-15

Abstract

We fabricate bifacial Cu2ZnSnSe4 (CZTSe) thin-film solar cells on indium tin oxide (ITO) substrates using a vacuum procedure. We find that, as the annealing temperature increases from 500 to 540 °C, the performance of the CZTSe solar cell rapidly degrades due to Sn–In diffusion. We implement Mo interlayers at the CZTSe absorber/ITO interface to suppress this Sn–In movement. During annealing, the selenized Mo interlayer with MoSe2 effectively acts as a barrier layer to reduce the In diffusion into the CZTSe absorber. The relationship between the Mo thickness and the CZTSe performance is addressed. Because the Mo interlayer is used, the conversion efficiency of the CZTSe solar cells greatly improves, from 0.40% to 5.21% under front illumination. Also, the effects of the bifacial conditions and Mo interlayer thickness on the performance of the CZTSe solar cells are investigated. Under bifacial illumination (front: 1.0 sun/rear: 0.3 sun), the conversion efficiency of the CZTSe solar cells increases by up to 10% compared with that under front illumination only, achieving a value of 5.71% for CZTSe/ITO. © 2018 Elsevier B.V.

URI  http://hdl.handle.net/20.500.11750/9243

Authors  Kang, Jang-Won; Kim, Byeong-Hyeok; Song, Hui; Jo, Yong-Ryun; Hong, Sang-Hyun; Jung, Gun Young; Kim, Bong-Joong; Park, Seong-Ju; Cho, Chang-Hee

Citation  Nanoscale, 10(31), 14812-14818

Abstract

Sincesemiconducting ZnO has attractive properties such as wide bandgap and largeexciton binding energy, it has motivated us to realize efficient ultraviolet(UV) light-emitting diodes (LEDs). Furthermore, facile growth of ZnOnanostructures has triggered numerous research studies to examine them asnanoscale building blocks for optoelectronic devices. Here, we demonstrate thegrowth of ZnO-based core-shell p-n homojunction nanorod arrays with radialMgZnO/ZnO multiple quantum wells (MQWs) and report the characteristics of acore-shell ZnO nanorod LED. The shell layers of MgZnO/ZnO MQWs and p-typeantimony-doped MgZnO were epitaxially grown on the surface of ZnO core nanorodarrays. By introducing the radial MQWs, the photoluminescence intensity wasgreatly increased by 4 times, compared to that of the bare ZnO nanorod array,suggesting that the core-shell MQWs can be used to realize the nanoscale ZnOLEDs with high internal quantum efficiency. As the injection current increased,the EL intensity of UV emission at 375 nm from the MgZnO/ZnO MQWs stronglyincreased without shifting of the emission peak because of the non-polar natureof MQWs grown on the side walls of the ZnO nanorods. These results highlightthe potential of an integrated nanoscale UV light emitter in various photonicdevices. © The Royal Society of Chemistry.

URI  http://hdl.handle.net/20.500.11750/9224

Authors  Cho, Jaehun; Miwa, Shinji; Yakushiji, Kay; Kubota, Hitoshi; Fukushima, Akio; You, Chun Yeol; Yuasa, Shinji; Suzuki, Yoshishige

Citation  Physical Review Applied, 10(1)

Abstract

Theexchange stiffness constant denoted by A(ex) is one of the fundamental physicalquantities from the Heisenberg exchange Hamiltonian for ferromagneticmaterials. A recent theoretical prediction shows the possibility that A(ex) inferromagnetic metal films can be effectively tuned by the application of anelectric field at the surface. In this paper, we demonstrate that the thermallyexcited spin-wave modes in magnetic tunnel junctions contain modulations uponapplication of an electric field through a MgO tunneling barrier. Differentmodulations of different spin-wave eigenmodes provide quantitative informationregarding the electric field effects on the exchange stiffness, perpendicularanisotropy energy, and saturation magnetization. An electric field of 1 V/nmmodulated A(ex) by 8.1% at room temperature. The results are significantlyhigher than those predicted from the Slater-Pauling curve and recenttheoretical work.

URI  http://hdl.handle.net/20.500.11750/9220

Authors  Lee, Jung Hun; Choi, Hyun Ho; Park, Yeong Don; Anthony, John E.; Lim, Jung Ah; Cho, Jang Whan; Chung, Dae Sung; Hwang, Jin Hyun; Jang, Ho Won; Cho, Kil Won; Lee, Wi Hyoung

Citation  Advanced Functional Materials

Abstract

http://hdl.handle.net/20.500.11750/9228

Authors  Kwon, Hye Kyeong; Jeong, Hyobin; Hwang, Daehee; Park, Zee-Yong

Citation  Biochimica et Biophysica Acta - Proteins and Proteomics,1866(10), 1043-1054

Abstract

Todetermine fundamental characteristics of pathological cardiac hypertrophy,protein expression profiles in two widely accepted models of cardiachypertrophy (swimming-trained mouse for physiological hypertrophy andpressure-overload-induced mouse for pathological hypertrophy) were comparedusing a label-free quantitative proteomics approach. Among 3955 proteins(19,235 peptides, false-discovery rate < 0.01) identified in these models,486 were differentially expressed with a log2 fold difference ≥ 0.58, or were detected in only onehypertrophy model (each protein from 4 technical replicates, p <.05).Analysis of gene ontology biological processes and KEGG pathways identifiedcellular processes enriched in one or both hypertrophy models. Processes uniqueto pathological hypertrophy were compared with processes previously identifiedin cardiac-hypertrophy models. Individual proteins with differential expressionin processes unique to pathological hypertrophy were further confirmed usingthe results of previous targeted functional analysis studies. Using aproteogenomic approach combining transcriptomic and proteomic analyses, similarpatterns of differential expression were observed for 23 proteins andcorresponding genes associated with pathological hypertrophy. A total of 11proteins were selected as early-stage pathological-hypertrophy biomarkercandidates, and the results of western blotting for five of these proteins inindependent samples confirmed the patterns of differential expression in mousemodels of pathological and physiological cardiac hypertrophy. © 2018 ElsevierB.V.

URI  http://hdl.handle.net/20.500.11750/9236

Authors  Yoo, Seong Hoon; Song, Hyeng Gun; Cho, Jang Whan; Kwon, Soon-Ki; Kim, Yun-Hi; Chung, Dae Sung

Citation  Chemistry of Materials, 30(14), 4808-4815

Abstract

Weintroduce a synthetic approach to enhance coalescence phenomenon duringsolidification of water-borne colloids so that thin, even, and continuous filmmorphology of polymer semiconductors can be realized. From the theoreticalstudy of complex colloids, we show that small-sized and uniform colloidparticles are essential to minimize depletion contact energy between colloidparticles and thus to enhance coalescence. Therefore, the newly synthesizedpolymer semiconductor in this study is designed with the aim of bettermolecular affinity with surfactants, so that phase transfer of polymersemiconductors from organic phase to water phase can proceed more efficientlyduring mini-emulsion synthesis. This is achieved by substituting a Si atom tothe branching C atom of the alkyl solubilizing group of a conventionaldonor-acceptor polymer semiconductor. Such a chemical modification increasesthe volumetric portion of hydrophobic alkyl chains and thus enables highersolubility as well as higher hydrophobicity, all of which are closely relatedwith enhancing molecular affinity between polymer semiconductor and surfactant,as proved by surface energy, dynamic light scattering, transmission electronmicroscopy, and scanning electron microscopy analyses. As a result, it is shownthat the performance of organic field-effect transistors fabricated fromwater-borne colloids can be improved to a level similar to the case of organicsolvents, 0.91 cm2 V-1 s-1. More importantly, we also show the reproducibilityof transistor performance is greatly improved due to the uniform and smallwater-borne colloidal particles. © 2018 American Chemical Society.

URI  http://hdl.handle.net/20.500.11750/9241

Authors  Lee, Yuree; Kwak, June Myoung

Citation  BMB Reports, 51(7), 317-318

Abstract

Plants areunable to relocate themselves to a more favorable location and thus have todeal with developmental programs and environmental cues wherever they happen tobe. It is yet largely unknown how plant cells coordinate cellular activitiesand architectures to accomplish developmental processes and respond toenvironmental changes. By identifying and establishing a new cellular modelsystem, we have discovered that two neighboring cell types in the abscissionzone (AZ) of Arabidopsis flowers coordinate their activities to ensure aprecise "cut" through a highly restricted area of plant tissue tobring about organ separation. From this perspective, we further discuss theessence of cellular coordination in AZ, the key molecules controlling the organseparation, and relevant implications.