http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Cho, Hyunjin,Kim, Yeonho,Yun, Yong Ju,Lee, Kyu Seung,Shim, Jaeho,Lee, Chil-Hyoung,Seo, Jin Won,Hong, Won G.,Kim, Hae Jin,Kim, Hak Yong,Son, Dong Ick Elsevier Science Ltd 2019 Composites Part B, Engineering Vol. No.
<P><B>Abstract</B></P> <P>We have developed a new and versatile three-dimensional (3D) porous and the conductive carbon spun fabric (CSF) structure and applied it to the current collector for advanced lithium-ion batteries (LIBs). The 3D porous CSF are manufactured from recycled oxidized polyacrylonitrile (Oxi-PAN) staple fibers via the spinning, the knitting, stabilization, and carbonization process in order. Furthermore, we have demonstrated the conductive T-shirts and gloves and investigated the structural, electrical, mechanical, and thermal properties of the CSF through various analytical methods including Joule heating simulation as well as the deformation simulation. The CSF with its 3D porous structure is applied as a current collector for advanced lithium batteries in order to replace the conventionally used metal-based current collector. During battery performances, the porous 3D network structure of the CSF provides effective diffusion pathway for lithium ions during the charge/discharge processes. Consequently, the CSF shows not only the improved cycling stability than that of the conventional aluminum current collector but also demonstrating high-rate performances at high percentage loading of active materials in the current collector. The pouch-type LIBs with the CSF/LiFePO<SUB>4</SUB> composites electrode exhibits excellent mechanical stability and flexibility with showing a discharge capacity of 148.7 mA h g<SUP>−1</SUP> at 2 C over 250 cycles over the 1200 times bending with a radius of 12 mm.</P> <P><B>Graphical abstract</B></P> <P>A new and versatile three-dimensional (3D) porous and the conductive carbon spun fabric (CSF) structure have been developed and have been applied it to the current collector for advanced lithium-ion batteries (LIBs).</P> <P>[DISPLAY OMISSION]</P>
Motor Function in School-Aged Children with Attention-Deficit/Hyperactivity Disorder in Korea
Hyunjin Cho,Seokyeon Ji,Sungho Chung,Meesun Kim,YooSook Joung 대한신경정신의학회 2014 PSYCHIATRY INVESTIGATION Vol.11 No.3
Objective-Motor function critically influences daily activities and academic performance. We compared motor function in schoolaged children with Attention-Deficit/ Hyperactivity Disorder (ADHD) to that of normal children. Methods-Participants were 58 children with ADHD [51 males, 7 females; mean age 9 years 6 months±2 years 0 months (SD)] and 70 normal controls [56 males, 14 females; mean age 9 years 2 months±1 years 7 months (SD)]. We assessed motor function with the Bruininks- Oseretsky Test of Motor Proficiency, Second Edition. Results-The ADHD group had a significantly lower total motor composite score (t=-9.32, p<0.001) than that of the control group. Standard scores of four motor-area composites such as fine manual control (t=-3.76, p<0.001), manual coordination (t=-6.87, p<0.001), body coordination (t=-7.14, p<0.001), and strength and agility (t=-8.54, p<0.1) were significantly lower in the ADHD group than those in the control group. Among the subtests, scores on fine motor precision, fine motor integration, manual dexterity, bilateral coordination, balance, running speed and agility, and strength were significantly lower in the ADHD group than those in the controls, whereas upper-limb coordination was not significantly different between the groups. Conclusion-School-aged children with ADHD in Korea had significantly lower motor function compared to that of controls. Thus, it is suggested that appropriate target intervention for motor function is important in children with motor impairment in addition to pharmacotherapy or psychosocial therapy for improving the core symptoms.
Parametric Study of Methanol Chemical Vapor Deposition Growth for Graphene
Hyunjin Cho,Changhyup Lee,In Seoup Oh,Sungchan Park,Hwan Chul Kim,Myung Jong Kim 한국탄소학회 2012 Carbon Letters Vol.13 No.4
Methanol as a carbon source in chemical vapor deposition (CVD) graphene has an advantage over methane and hydrogen in that we can avoid optimizing an etching reagent condition. Since methanol itself can easily decompose into hydrocarbon and water (an etching reagent) at high temperatures [1], the pressure and the temperature of methanol are the only parameters we have to handle. In this study, synthetic conditions for highly crystalline and large area graphene have been optimized by adjusting pressure and temperature; the effect of each parameter was analyzed systematically by Raman, scanning electron microscope, transmission electron microscope, atomic force microscope, four-point-probe measurement, and UV-Vis. Defect density of graphene, represented by D/G ratio in Raman, decreased with increasing temperature and decreasing pressure; it negatively affected electrical conductivity. From our process and various analyses, methanol CVD growth for graphene has been found to be a safe, cheap, easy, and simple method to produce high quality, large area, and continuous graphene films.
Graphene–Carbon–Metal Composite Film for a Flexible Heat Sink
Cho, Hyunjin,Rho, Hokyun,Kim, Jun Hee,Chae, Su-Hyeong,Pham, Thang Viet,Seo, Tae Hoon,Kim, Hak Yong,Ha, Jun-Seok,Kim, Hwan Chul,Lee, Sang Hyun,Kim, Myung Jong American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.46
<P>The heat generated from electronic devices such as light emitting diodes (LEDs), batteries, and highly integrated transistors is one of the major causes obstructing the improvement of their performance and reliability. Herein, we report a comprehensive method to dissipate the generated heat to a vast area by using the new type of graphene carbon metal composite film as a heat sink. The unique porous graphene-carbon-metal composite film that consists of an electrospun carbon nanofiber with arc-graphene (Arc-G) fillers and an electrochemically deposited copper (Cu) layer showed not only high electrical and thermal conductivity but also high mechanical stability. Accordingly, superior thermal management of LED devices to that of conventional Cu plates and excellent resistance stability during the repeated 10 000 bending cycles has been achieved. The heat dissipation of LEDs has been enhanced by the high heat conduction in the composite film, heat convection in the air flow, and thermal radiation at low temperature in the porous carbon structure. This result reveals that the graphene carbon metal composite film is one of the most promising materials for modern electronics.</P>
Cho, Hyunjin,Kim, Whi Dong,Lee, Kangha,Lee, Seokwon,Kang, Gil-Seong,Joh, Han-Ik,Lee, Doh C. Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.429 No.-
<P><B>Abstract</B></P> <P>We investigate the product selectivity of CO<SUB>2</SUB> reduction using NiO photocathodes decorated with CdSe quantum dots (QDs) of varying size in a photoelectrochemical (PEC) cell. Size-tunable and quantized energy states of conduction band in CdSe QDs enable systematic control of electron transfer kinetics from CdSe QDs to NiO. It turns out that different size of CdSe QDs results in variation in product selectivity for CO<SUB>2</SUB> reduction. The energy gap between conduction band edge and redox potential of each reduction product (<I>e.g.</I>, CO and CH<SUB>4</SUB>) correlates with their production rate. The size dependence of the electron transfer rate estimated from the energy gap is in agreement with the selectivity of CO<SUB>2</SUB> reduction products for all reduction products but CO. The deviation in the case of CO is attributed to sequential conversion of CO into CH<SUB>4</SUB> with CO adsorbed on electrode surface. Based on a premise that the CdSe QDs would exhibit similar surface configuration regardless of QD size, it is concluded that the electron transfer kinetics proves to alter the selectivity of CO<SUB>2</SUB> reduction.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Size-tunable energy states of conduction band in CdSe quantum dots enable systematic control of product selectivity for CO<SUB>2</SUB> reduction. </LI> <LI> The energy gap between conduction band edge and redox potential of each reduction product correlates with their production rate. </LI> <LI> The electron transfer kinetics proves to alter the selectivity of CO<SUB>2</SUB> reduction. </LI> </UL> </P>