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Han, Jusung,Kim, Kihyun,Kim, Junghwan,Kim, Sungjun,Choi, So-Won,Lee, Hyunhee,Kim, Jin-joo,Kim, Tae-Ho,Sung, Yung-Eun,Lee, Jong-Chan Elsevier 2019 Journal of membrane science Vol.579 No.-
<P><B>Abstract</B></P> <P>End-group cross-linked sulfonated poly(arylene ether sulfone) (SPAES) membranes were prepared using thiol capped SPAES (SH-SPAES) with different amounts of vinyl polysulfone (VPSf) as a polymeric cross-linker. The cross-linked membranes showed remarkably improved physicochemical stabilities compared to the corresponding linear SPAES membrane. Although the proton conductivity of the SPAES membrane composed of SPAES with the degree of sulfonation (DS) as 70 mol% could not be measured due to its low physical stability under the measurement condition, those of the cross-linked membranes were repeatedly evaluated due to the enhanced stability through the formation of cross-linked structures. The obtained proton conductivity values from cross-linked membranes are larger than those of the linear SPAES membrane which composed of SPAES with DS of 50 mol% having the ion exchange capacity (IEC) similar to that of the cross-linked membranes, especially at relative low humidity conditions. Furthermore, the fuel cell performance of the membrane electrode assembly (MEA) prepared with the cross-linked membrane, showing the optimized physicochemical stabilities and proton conductivity exhibited a maximum power density of 692 mW cm<SUP>−2</SUP>, which was larger than that with Nafion 212 (603 mW cm<SUP>−2</SUP>) at 80 °C under fully humidified H<SUB>2</SUB>/Air condition.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Thiol group capped highly sulfonated poly(arylene ether sulfone) and vinyl group containing poly sulfone were synthesized. </LI> <LI> End group cross-linked membranes were prepared by thiol-ene click reaction using polymeric cross-linker. </LI> <LI> Excellent physicochemical stability of end group cross-linked membranes. </LI> <LI> High proton conductivity of end group cross-linked membranes in low humidity condition. </LI> <LI> Outstanding cell performance of MEA prepared with end group cross-linked membrane. </LI> </UL> </P>
김기훈(Kihoon Kim),김경호(Kyungho Kim),김형탁(Hyoungtak Kim),이주성(Jusung Lee),신민철(Mincheol Shin),김창원(Changwon Kim),윤진한(Jinhan Yun),이정규(Jungkyu Lee),홍원석(Wonseok Hong) 한국환경에너지공학회 2023 한국열환경공학회 학술대회지 Vol.2023 No.1
선택 적 비촉매 환원법 (Selective Non-Catalytic Reduction)은 소각로의 연소실 내부로 환원제를 주입하여 연소과정에서 발생하는 질소산화물을 제거하는 기술이다. 대부분의 소각시설에서는 환원제로 요소수를 사용하고 있으며, 이류체 노즐을 통하여 분사된 요소수는 연소가스 중 질소산화물을 질소와 수증기로 환원시킨다. 이러한 선택적 비촉매 환원법의 경우에 초기 투자비 및 유지비가 적다는 장점이 있으나 요소수가 액상으로 주입되기 때문에 질소산화물과의 반웅 효율이 낮아 일부 미반응된 요소수가 대기 중으로 배출되는 암모니아 슬립 발생에 대한 문제점이 있다. 또한 계속해서 강화되는 대기오염물질 배출허용기준과 미세먼지 관리 종합대책의 후속 조치로 질소산화물 배출 부과금제가 시행됨에 따라 기존의 소각시설들은 질소산화물의 관리를 강화할 수 있는 현실적인 대책이 필요한 실정이다. 따라서 본 연구에서는 요소수를 기화시킨 후 소각로 내부로 주입하여 암모니아 슬립 발생은 줄이면서 질소산화물의 저감 효율은 극대화하고자 하였으며, 추가적인 가열설비의 구축 없이 소각로에서 발생되는 폐열을 활용하여 이를 구현하고자 하였다. 요소수의 기화 및 주입을 위하여 소각로 잉여 열원의 현황을 파악하고 운영조건을 사전에 검토하였으며, 온도와 압력에 따른 요소수의 기화 특성을 실험적으로 확인하여 설비 제작을 위한 설계 인자를 도출하였다.
BLE 응용을 위한 2.4GHz 대역의 CMOS RF 송수신기 설계
김광순(Kwangsoon Kim),정기상(Kisang Jung),김규형(Kyuhyung Kim),이상훈(Sanghun Lee),김성완(Sung-Wan Kim),이평한(Pyeong-Han Lee),박광범(Kwang-Beom Park),천성훈(Sung-Hun Chun),류창호(Chang-Ho Ryu),안광호(Kwang-Ho Ahn),김주성(Jusung Kim) 대한전자공학회 2018 대한전자공학회 학술대회 Vol.2018 No.11
In this paper, a 2.4GHz CMOS RF transceiver design for BLE(Bluetooth Low Energy) application is presented. The fully-differential RF transceiver is compliant with Bluetooth core specification v5.0. The transceiver is comprised of low-IF receiver and zero-IF transmitter. The overall DC current consumption for continuous Tx transmission at +0dBm output power is 12mA and for continuous Rx reception at –90dBm sensitivity is 13mA. The transceiver is fabricated in 90nm CMOS process and total die size is 5.74mm2 including baseband modem and electrostatic discharge I/O pads.
A Low-Complexity I/Q Imbalance Calibration Method for Quadrature Modulator
Kim, Jusung,Jo, Han-Shin,Lee, Kyoung-Jae,Lee, Dong-Ho,Choi, Dae-Hyun,Kim, Sangkil IEEE 2019 IEEE transactions on very large scale integration Vol.27 No.4
<P>This brief presents a low-complexity I/Q (in-phase and quadrature components) imbalance calibration method for the transmitter using quadrature modulation. Impairments in analog quadrature modulator have a deleterious effect on the signal fidelity. Among the critical impairments, I/Q imbalance (gain and phase mismatches) deteriorates the residual sideband performance of the analog quadrature modulator degrading the error vector magnitude. Based on the theoretical mismatch analysis of the quadrature modulator, we propose a low-complexity I/Q imbalance extraction algorithm. After the parameter extraction, the transmitter is calibrated by imposing the counter imbalanced mismatch of the transmitter through the digital baseband. In comparison with existing I/Q imbalance calibration methods, the novelty of the proposed method lies in that: 1) only three spectrum measurements of the device-under-test are needed for extraction and calibration of gain and phase mismatches; 2) due to the blind nature of the calibration algorithm, the proposed approach can be readily applicable to an existing I/Q transmitter; 3) no extra hardware that degrades the calibration accuracy is required; and 4) due to the noniterative nature, the proposed method is faster and computationally more efficient than previously published methods.</P>
Kim, Kihyun,Heo, Pilwon,Han, Jusung,Kim, Junghwan,Lee, Jong-Chan Elsevier 2018 Journal of Power Sources Vol.401 No.-
<P><B>Abstract</B></P> <P>End-group cross-linked sulfonated poly (arylene ether sulfone) (C-SPAES) membranes with varying degree of cross-linking density are prepared by <I>in-situ</I> casting and heating of thiol-terminated SPAES (SH-SPAES) solutions containing different amounts of multifunctional cross-linker such as acrylo-polyhedral oligomeric silsesquioxane (A-POSS) <I>via</I> thiol-ene click reaction. SH-SPAES is prepared by stepwise substitution reactions between phenoxide-terminated SPAES and end capping reagents such as decafluorobiphenyl followed by thiobisbenzethiol. The C-SPAES membranes exhibit vastly improved chemical and physical stability and mechanical strength compared with linear SPAES membrane due to effective cross-linked structure, and their proton conductivity values are higher than Nafion-212 in relative humidity range of 50–95% (at 90 °C) due to high degree of sulfonation (70 mol%) and ion exchange capacity (2.48 mequiv. g<SUP>−1</SUP>) of SH-SPAES. Under various operating conditions of proton exchange membrane fuel cell including intermediate temperature and low humidity conditions, membrane electrode assemblies employing the C-SPAES membranes with optimized cross-linker contents show outstanding cell performances (e.g., 1.08 W cm<SUP>-2</SUP> at 0.5 V under 90 °C and 50% RH with 150 kPa).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Thiol terminated sulfonated poly (arylene ether sulfone) (SH-SPAES) is synthesized. </LI> <LI> SH-SPAES has high degree of sulfonation and ion exchange capacity. </LI> <LI> End-group cross-linked SPAES membranes are prepared by thiol-ene click reaction. </LI> <LI> Excellent physicochemical stability of cross-linked SPAES membranes. </LI> <LI> Outstanding cell performances of MEAs prepared with cross-linked SPAES membranes. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Kim, Jusung,Kwak, Juho,Kim, Dukjoon Wiley Subscription Services, Inc., A Wiley Company 2007 Journal of applied polymer science Vol.106 No.6
<P>PMMA nanoparticles with highly mono-dispersed size distribution were prepared using the RAFT living radical emulsion polymerization technique. A novel sur-iniferter for the RAFT reaction, DTBA, was synthesized and its chemical structure was identified using several spectroscopic techniques. The relationship between the particle size and the molecular weight of the polymer was investigated measuring the rate of growth of each during formation of particles, and was well explained by the simple random flight molecular conformation model. The particle size increased up to a certain value with decreasing sur-iniferter concentration and then leveled off, because the surface charge density of the growing particles was not high enough to stabilize the particles in aqueous medium above that value. The core-shell type di-block copolymer nanoparticles were also successfully prepared via RAFT reaction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007</P>
Chung, Jusung,Tak, Young Jun,Kim, Won-Gi,Park, Jeong Woo,Kim, Tae Sang,Lim, Jun Hyung,Kim, Hyun Jae The Royal Society of Chemistry 2018 Journal of Materials Chemistry C Vol.6 No.18
<P>We proposed a simple method, a thermally purified solution (TPS) process, to lower the fabrication temperature of solution-processed hafnium oxide (HfOx) gate insulator films. The TPS process is proceeded by transferring thermal energy to the HfOx precursor solution ‘BEFORE’ film formation. The TPS process could induce chemical reactions including pre-hydrolysis by thermal energy in the HfOx precursor solution. These chemical reactions reduce the required thermal energy for forming a solution-processed HfOx film and improve the film quality. As a result, the HfOx film fabricated <I>via</I> the TPS process has satisfactory dielectric characteristics: a breakdown electric field of ∼6 MV cm<SUP>−1</SUP>, a leakage current density of ∼10<SUP>−9</SUP> A cm<SUP>−2</SUP>, and a dielectric constant of 10.23 at low temperatures, <I>i.e.</I>, below 200 °C. Solution-processed indium oxide (In2O3) thin film transistors with a HfOx gate insulator fabricated <I>via</I> the TPS process exhibit a field effect mobility of 3.67 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, an on/off current ratio of 9.8 × 10<SUP>6</SUP>, and a subthreshold swing of 0.18 V dec<SUP>−1</SUP>.</P>