http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Coffee-Driven Green Activation of Cellulose and Its Use for All-Paper Flexible Supercapacitors
Lee, Donggue,Cho, Yoon-Gyo,Song, Hyun-Kon,Chun, Sang-Jin,Park, Sang-Bum,Choi, Don-Ha,Lee, Sun-Young,Yoo, JongTae,Lee, Sang-Young American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.27
<P>Cellulose, which is one of the most-abundant and-renewable natural resources, has been extensively explored as an alternative substance for electrode materials such as activated carbons. Here, we demonstrate a new class of coffee-mediated green activation of cellulose as a new environmentally benign chemical-activation strategy and its potential use for all-paper flexible supercapacitors. A piece of paper towel is soaked in espresso coffee (acting as a natural activating agent) and then pyrolyzed to yield paper-derived activated carbons (denoted as 'EK-ACs'). Potassium ions (K+), a core ingredient of espresso, play a viable role in facilitating pyrolysis kinetics and also in achieving a well-developed microporous structure in the EK-ACs. As a result, the EK-ACs show significant improvement in specific capacitance (131 F g(-1) at a scan rate of 1.0 mV s(-1)) over control ACs (64 F g(-1)) obtained from the carbonization of a pristine paper towel. All-paper flexible supercapacitors are fabricated by assembling EKACs/carbon nanotube mixture-embedded paper towels (as electrodes), poly(vinyl alcohol)/KOH mixture-impregnated paper towels (as electrolytes), and polydimethylsiloxane-infiltrated paper towels (as packaging substances). The introduction of the EKACs (as an electrode material) and the paper towel (as a deformable and compliant substrate) enables the resulting all-paper supercapacitor to provide reliable and sustainable cell perforinance as well as exceptional mechanical flexibility. Notably, no appreciable loss in the cell capacitance is observed after repeated bending (over 5000 cycles) or multiple folding. The coffee mediated green activation of cellulose and the resultant all-paper flexible supercapacitors open new material and system opportunities for eco-friendly high-performance flexible power sources.</P>
Donggu Lee,Kuduck Kwon 대한전자공학회 2022 Journal of semiconductor technology and science Vol.22 No.3
This paper presents a blocker-tolerant broadband balun-low-noise transconductance amplifier (LNTA) with a high-Q dual-band LC notch filter for 5G new radio (NR) sub-6GHz cellular applications. The proposed balun-LNTA employs a noise-cancelling 1:5 CG-CS balun-LNA topology with local feedback gm-boosting and modified currentbleeding techniques to support entire bands of sub-6 GHz 5G NR application with less than 5 dB NF performance and balanced output of balun-LNTA. The dual-band Q-boosted LC notch filter with a bandswitchable differential inductor is also proposed to enhance blocker tolerance of the receiver by removing out-of-band blockers and strong transmitter leakage signals. Simulated in a 65-nm CMOS process, the designed balun-LNTA achieves a minimum noise figure of 2.38 dB, a maximum transconductance gain of 44 mS, an S11 of less than ‒10 dB over the frequency range of 50 MHz-6 GHz, an input-referred third-order intercept point of 1.82 dBm, and blocker rejection ratios of more than 15 dB. It consumes 5.9 mA from a nominal supply voltage of 1 V. Its active die area is 0.55 mm2.
Donggu Lee,Kuduck Kwon 대한전자공학회 2020 Journal of semiconductor technology and science Vol.20 No.5
In this paper, a CMOS tunable channel-selection low-noise amplifier (LNA) that employs an active feedback technique and gain-boosted N-path bandpass filter (BPF) is presented for advanced cellular applications. The proposed LNA achieves broadband input power matching and low noise figure (NF) performance by using the active feedback technique. The gain-boosted N-path BPF is also used to implement a high-Q RF fourth-order bandpass filtering. Simulated in a 65-nm CMOS process, the proposed LNA achieves a maximum voltage gain of 17 dB, minimum NF of 2.16 dB, maximum out-of-band blocker rejection ratio of 21 dB at 80 MHz offset frequency. The center-frequency tuning range of the LNA is 0.1 ‒ 4 GHz, which includes all FDD bands in the 3G/4G/5G sub-6 GHz cellular standards. It draws a DC bias current of 21 mA from a supply voltage of 1.2 V. The active die area is 0.8 mm2.
Flexible/Rechargeable Zn-Air Batteries Based on Multifunctional Heteronanomat Architecture
Lee, Donggue,Kim, Hyun-Woo,Kim, Ju-Myung,Kim, Ka-Hyun,Lee, Sang-Young American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.26
<P>The increasing demand for advanced rechargeable batteries spurs development of new power sources beyond currently most widespread lithium-ion batteries. Here, we demonstrate a new class of flexible/rechargeable zinc (Zn)-air batteries based on multifunctional heteronanomat architecture as a scalable/versatile strategy to address this issue. In contrast to conventional electrodes that are mostly prepared by slurry-casting techniques, heteronanomat (denoted as “HM”) framework-supported electrodes are fabricated through one-pot concurrent electrospraying (for electrode powders/single-walled carbon nanotubes (SWCNTs)) and electrospinning (for polyetherimide (PEI) nanofibers) process. Zn powders (in anodes) and rambutan-shaped cobalt oxide (Co<SUB>3</SUB>O<SUB>4</SUB>)/multiwalled carbon nanotube (MWCNT) composite powders (in cathodes) are used as electrode active materials for proof of concept. The Zn (or Co<SUB>3</SUB>O<SUB>4</SUB>/MWCNT) powders are densely packed and spatially bound by the all-fibrous HM frameworks that consist of PEI nanofibers (for structural stability)/SWCNTs (for electrical conduction) networks, leading to the formation of three-dimensional bicontinuous ion/electron transport channels in the electrodes. The HM electrodes are assembled with cross-linked polyvinyl alcohol/polyvinyl acrylic acid gel polymer electrolytes (acting as zincate ion crossover-suppressing, permselective separator membranes). Benefiting from its unique structure and chemical functionalities, the HM-structured Zn-air cell significantly improves mechanical flexibility and electrochemical rechargeability, which are difficult to achieve with conventional Zn-air battery technologies.</P> [FIG OMISSION]</BR>
다양한 박막 형성법을 사용한 ZnO 전자 추출층이 역구조 고분자 태양전지에 미치는 영향 연구
이동구(Donggu Lee),노승욱(Seunguk Noh),성명모(Myungmo Sung),이창희(Changhee Lee) 한국태양광발전학회 2013 Current Photovoltaic Research Vol.1 No.1
We investigated the effects of ZnO thin film deposition methods on the performance of inverted polymer solar cells with a structure of ITO/ZnO/P3HT:PCBM/MoO3/Al. The ZnO thin films were deposited by various methods (spin coating of nanoparticles, sol-gel process, atomic layer deposition) and their morphology was analyzed by atomic force microscopy (AFM). The device with ZnO nanoparticle thin films showed the highest power conversion efficiency of 3 % with low series resistance and high shunt resistance. The superior performance of the device with the ZnO nanoparticle layer is attributed to better electron extraction capability.
Jeon, Donggu,Lee, Wonchoel,Soh, Ho Young Pensoft Publishers 2019 ZooKeys Vol.814 No.-
<P>Abstract</P><P>Male monstrilloid copepods belonging to the genus <I>Caromiobenella</I> Jeon, Lee & Soh, 2018 were collected from Chuja Island, Jeju, Korea, using a light trap. This paper describes a new species, <I>Caromiobenellaohtsukai</I><B>sp. n.</B>, based on the display of reduced, knob-like fifth legs on the ventral side of the first urosomal somite. A unique combination of male genitalia features and number of caudal setae further confirms its specificity. Molecular analysis based on two partial gene sequences of mitochondrial cytochrome <I>c</I> oxidase subunit I (mtCOI) and 28S ribosomal RNA (28S rRNA) also supports the designation of this species by showing a relevant divergence from known congeners. <I>Caromiobenellaohtsukai</I><B>sp. n.</B> is the ninth member of this genus and also the ninth monstrilloid reported from Korea.</P>