Crosslinked anion exchange membranes with primary diamine-based crosslinkers for vanadium redox flow battery application

Cha, Min Suc,Jeong, Hwan Yeop,Shin, Hee Young,Hong, Soo Hyun,Kim, Tae-Ho,Oh, Seong-Geun,Lee, Jang Yong,Hong, Young Taik Elsevier 2017 Journal of Power Sources Vol.363 No.-

<P><B>Abstract</B></P> <P>A series of polysulfone-based crosslinked anion exchange membranes (AEMs) with primary diamine-based crosslinkers has been prepared via simple a crosslinking process as low-cost and durable membranes for vanadium redox flow batteries (VRFBs). Chloromethylated polysulfone is used as a precursor polymer for crosslinked AEMs (CAPSU-x) with different degrees of crosslinking. Among the developed AEMs, CAPSU-2.5 shows outstanding dimensional stability and anion (Cl<SUP>−</SUP>, SO<SUB>4</SUB> <SUP>2−</SUP>, and OH<SUP>−</SUP>) conductivity. Moreover, CAPSU-2.5 exhibits much lower vanadium ion permeability (2.72 × 10<SUP>−8</SUP> cm<SUP>2</SUP> min<SUP>−1</SUP>) than Nafion 115 (2.88 × 10<SUP>−6</SUP> cm<SUP>2</SUP> min<SUP>−1</SUP>), which results in an excellent coulombic efficiency of 100%. The chemical and operational stabilities of the membranes have been investigated via ex situ soaking tests in 0.1 M VO<SUB>2</SUB> <SUP>+</SUP> solution and in situ operation tests for 100 cycles, respectively. The excellent chemical, physical, and electrochemical properties of the CAPSU-2.5 membrane make it suitable for use in VRFBs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The crosslinking between polymer chains are constructed by 4,4′-diaminobenzophenone. </LI> <LI> The crosslinked AEMs were fabricated by commercial polysulfone (PSU; Udel<SUP>®</SUP> P-3500). </LI> <LI> The crosslinked AEM based on PSU indicated good chemical and dimensional stability. </LI> <LI> The performance of crosslinked AEM showed high EE (86%) with high capacity retention. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

이종접합재 접합 계면근방 균열의 응력 및 파괴특성

오정국,차용훈,오환섭,박준건,박경식 朝鮮大學校 機械技術硏究所 1998 機械技術硏究 Vol.1 No.1

현재까지 이종마찰압접재의 강도측정은 실험 (7)-(15)에 의해 구해져 왔다. 하지만 최근 이종마찰압접재의 효율성을 인정하여 여러 실용 부품에 응용하려는 연구가 한창 진행중이다. 이종마찰압접재에 대한 저자들(1)-(6)의 기초실험결과 일반적인 단종재와는 상이한 파괴거동(3)이 관찰되었고, 파괴역학적인 관점에서 정성적인 data 확보가 필요하게 되었다. 따라서 본 연구에서는 인장시험시 이종마찰압접재의 접합강도와 미소균열들에 의한 파괴거동을 파괴역학적 관점에서 해석적으로 고찰하여 보고자 경계요소법(BEM ; Boundary Element Method)을 이용하여 접합계면을 포함하는 접합부를 중심으로 계면상의 응력분포와 계면의 중앙에 결함이 균열로써 존재하는 경우의 응력분포와 인장시험시 열영향부에서 관찰된 균열의 모델링을 통한 균열선단에서의 응력해석을 행하였고, 그 결과 얻어진 중요한 내용을 요약하면 다음과 같다. 계면의 중앙에 균열이 존재하는 접합계면의 표면부에서 응력의 특이성이 발생하며 탄성계수의 비가 증가할수록 특이성이 증가함이 관찰되었다. 탄성계수의 비가 일정한 경우 균열의 크기가 변화하여도 계면의 표면부에서 발생하는 특이성은 거의 같은 값을 갖게 되며, 탄성계수의 비가 증가할수록 표면부의 응력 특이성의 크기는 증가한다. 이종마찰압접재의 인장시험시 관찰된 균열을 모델링 하여 해석한 결과 최대 응력 기준으로 살펴볼 때 인접한 균열선단에서의 응력분포는 균열을 합체시키는 방향으로 작용함을 알 수 있다. In this study stress distribution on the interface and stress near tip of the sub-interface crack in the dissimilar friction welded material is analyzed by using of BEM( Boundary Element Method). Stress singularity near surface of model to analyze is observed for various crack length and ratio of elastic modulus. Tensile and shear stress distribution near two neithbor sub-interface crack tips are analyzed. Existance of singularity near surface on the interface is particular situation so that we need to investigate for dissimilar friction welded materials by means of numerical analysis method.

친환경농업 농가 컨설팅에 대한 반응 조사

오환중,차광홍,정우진,김길용,박노동 全南大學校 農業科學技術硏究所 2011 農業科學技術硏究 Vol.46 No.-

The interactions between Environment-Friendly Agriculture Research Center (EFARC) and farmers in Jeonnam Province area who have practiced environment-friendly agriculture (EFA) under guidances of EFARC were investigated through enquete. The enquete was conducted during July - September, 2010. One hundred and eighty nine farmers responded all inquiries among 200 farmers. The main results are summarized as follows: 1. Rice was the predominant crop grown by farmers (49%), and the next major was hot pepper (12%). Most farmers (95.3%) have practiced environment-friendly agriculture at the levels of no-pesticide (55.6%), lower pesticide (32.8%), and organic (6.9%). 2. Major motivations of practicing EFA are for the production of safe foodstuffs (52.6%) and for an increase of income (40.1%). 3. Around 3 quarters of the environment-friendly agriculture products are shipped through Nonghyup, the cooperative marketing. The price margin between ordinary agriculture products and EFA products was of 5~10% for 63.5% farmers, of 10~20% for 14.3% ones, and of 20~30% for 14.8% ones. 4. Bottlenecks for practicing EFA are in the order of the unstability of shipping price (34.9%), cultivation techniques (20.1%), excess labor input (19.6%), and control of disease and insect pest (18%). 5. It turned out that more than 90% farmers who have practiced EFA under guidance of EFARC recognized the consulting activities of EFARC as to be helpful for them. 6. Establishment of national organizations which are specialized in consultation for EFApracticing farmers has been suggested.

Preparation and characterization of crosslinked anion exchange membrane (AEM) materials with poly(phenylene ether)-based short hydrophilic block for use in electrochemical applications

Cha, Min Suc,Lee, Jang Yong,Kim, Tae-Ho,Jeong, Hwan Yeop,Shin, Hee Young,Oh, Seong-Geun,Hong, Young Taik Elsevier 2017 Journal of membrane science Vol.530 No.-

<P><B>Abstract</B></P> <P>Herein, our group report the investigation of cross-linked copolymer anion exchange membrane (AEM) materials with a partially rigid backbone structure based on poly(phenylene ether). Two types of quaternized AEM materials, QCPPAE-2/1 and QCPPAE-4/1, with an ion exchange capacity (IEC) of 1.08 and 1.75meq/g, respectively, were synthesized. The cross-linked AEMs exhibited a low water uptake (WU) and dimensional change and outstanding anion (Cl<SUP>−</SUP>, SO<SUB>4</SUB> <SUP>2−</SUP>, and OH<SUP>−</SUP>) conductivities. The nanoscale phase-separated morphologies of the polymer membranes were characterized using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The synthesized membranes were introduced as a solid electrolyte into a vanadium redox flow battery (VRFB) and an anion exchange membrane fuel cell (AEMFC). The QCPPAE-2/1 membrane showed excellent coulombic efficiency (CE) of 99%, voltage efficiency (VE) of 88% and energy efficiency (EE) of 89% in VRFBs. Within AEMFCs, these membranes generated an outstanding power density as high as 106mW/cm<SUP>2</SUP> at 60°C.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Rigid backbone structure was synthesized via Ni (0)-cross coupling reaction. </LI> <LI> The crosslinking between polymer chains are constructed by 4,4’-diaminobenzophenone. </LI> <LI> The performance of crosslinked AEM showed high EE (88%>) and CE (99%>) in VRFB. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

외부광궤환에 의한 레이저 다이오드의 출력특성

이세영,오차환,김필수,황의중 漢陽大學校 自然科學硏究所 1997 自然科學論文集 Vol.16 No.-

외부 광궤환 반도체 레이저의 출력 특성을 비율방정식의 수치해를 이용하여 분석하였다. 출력의 세기와 위상과 전자밀도를 시간에 대한 함수로 알아보았다. 또한 bifurcation diagram과 phase diagram을 통하여 궤환비율 k에 따른 레이저의 동작 특성을 조사하였다. 궤환광이 없을때는 이완발진이 감쇄한 후 안정한 출력특성이 나타나지만 되먹임 비율이 증가하면서 안정한 해의 갯수가 증가하다가 ??????이상의 매우 강한 광궤환에서는 출력특성이 극도로 불규칙해지고 무수히 많은 해를 갖는 혼돈현상이 나타남을 알 수 있었다. The output characteristics of a laser diode with external optical feedback were analyzed by numerical solutions of rate equations. The output power, phase and carrier density were plotted as a function of time. Dynamics of external cavity laser were investigated by the bifurcation diagram and the phase diagram with respect to the feedback rate k. If there was no feedback, relaxation oscillation reduced and laser showed stable output. For increasing feed back level, the number of stable state was increased. In very strong feedback rate above ??????, laser output showed extremely unstable and chaotic behavior.

InGaAsP/InP 양자우물 구조의 물성연구

김채옥,오차환,문승준,김의훈 漢陽大學校 自然科學硏究所 1997 自然科學論文集 Vol.16 No.-

Liquid phase epitaxy(LPE)법에 의해 InGaAsP quantum well(QW)구조를 성장하여 특성을 photoluminescence(PL)와 double crystal rocking curve(DCRC)를 이용하여 조사하였다. PL 측정결과, 상온 PL의 경우 well특성의 피크 에너지는 0.97eV이 FWHM은 80.41meV이며, 저온PL결과 well특성의 피크 에너지는 1.025eV이고 FWHM은 33meV이었다. 여기광의 세기를 증가시킴에 따라 PL 세기가 비교적 선형적으로 급준한 증가를 보이고 있어 well발광 특성임을 관찰할 수 있었다. DCRC결과, 격자부정합도가 0.32이고 한 쌍의 주기는 600Å이며 전형적인 Quantum Well특성의 위성피크를 관찰할 수 있다. In this work, We have grown the InGaAsP/InP quantum well by liquid phase epitaxy(LPE) and its some physical properties have been studied by photoluminescence(PL) and double crystal x-ray rocking curve(DCRC). In low temperature PL, the characteristic emission peak of well is observed at 1.025eV with a full-with-half-maximum of 33meV. As we increase the excitation intensities the emission intensities are drastically increased. From the DCRC analysis, we know that lattice mismatch between epitaxial layer and substrate is very low with a value of 0.32.

LPE법에 의한 InGaAsP/InP 양자우물 구조 성장

김의훈,오차환,문승준,김채옥 漢陽大學校 自然科學硏究所 1997 自然科學論文集 Vol.16 No.-

InGaAsP /InP 양자우물 구조를 액상 에피탁시법으로 성장하여, 그 구조적 특성을 secondary ion mass spectroscopy(SIMS), scanning emission microscopy(SEM), transmission electron microscopy(TEM)을 이용하여 조사하였다. SIMS 결과로 부터 well과 barrier의 interface에서 P와 As의 성분이 매우 급준한 변화를 보이고 있는 것으로 보아 LPE로 성장된 시료의 계면구조도 비교적 잘 control이 되었다고 판단된다. SEM과 TEM단면 사진으로 부터 well과 barrier의 계면 상태가 양호하고 well size가 270Å이고 barrier size가 1200Å임을 알 수 있었다. InGaAsP /InP quantum well structures have been grown by liquid phase epitaxy(LPE) and its structural properties have been studied by SIMS, SEM and TEM. In SIMS measurement, the P - and As-components were varied abruptly between wells and barriers, which means that interfacial structures of sample grown by LPE were controlled very well. From the analysis of cross sectional images by SEM and TEM, we know that the interfaces between wells and barriers are very abrupt and that the thickness of well layers and barrier layers are 270Å and 1200Å, respectively .

아조벤젠 분자(Disperse Red 1)를 포함한 측쇄형 고분자에서 광유도 복굴절의 실시간적 조사

신희득,주원제,오차환,송석호,김필수,한양규 한양대학교 자연과학연구소 2001 自然科學論文集 Vol.20 No.-

아조벤젠 그룹을 포함한 측쇄형 고분자 필름(PDR1)에서 광 유도된 이방성을 실시간적으로 조사하였다. 수평, 수직한 흡수율의 변화를 광 유도된 복굴절의 기록, 감쇠, 소거, 완화 과정에 따라 측정하여, 매질 내의 아조벤젠 분자의 정렬상태와 복굴절과의 관계를 광 이성화과정으로 설명하였다. 또한 기록빔의 세기를 따른 수직, 수평한 흡수율의 변화와 유도된 복굴절의 관계를 조사하였다. The photo-induced anisotropy for a polymeric film(PDR1) containing azobenzene group as side-chain was investigated dynamically. The change of absrobances with parallel and perpendicular components was measured in recording, decaying, erasing and relaxation processes of photo-induced birefringence, so the relation between the alignment of azobenzene groups and the birefringence was well explained according to the photo-isomerization. Also, the dependence of the photo-induced birefringence on intensity of recording beam was investigated with changes of both absorbance and birefringence.

정확한 완충기체효과가 적용된 질량분석원리에 대한 다중입자 분석 전산시늉

이유용,이원욱,오차환,김필수,송석호 한양대학교 자연과학연구소 2001 自然科學論文集 Vol.20 No.-

질량분석기로 사용되는 폴 트랩 내에서 보다 실제적인 이온운동을 예측해내기 위하여 약 2천 개의 다중입자의 궤적에 대한 계산을 실시하였다. 보다 정확한 질량 분석스펙트럼을 얻기 위하여 충돌확률에 대한 보다 정확하고 실질적인 함수 값을 도입하였다. 계산된 전산시늉의 결과들로부터 특히 작은 질량의 영역에 대한 분석을 할 경우 본 논문에서 제시된 바와 같이 매우 정확한 충돌확률이 고려되어야 함을 확인할 수 있었다. To predict the practical characteristics of ion motion in the paul trap as a mass spectrometer, the ion trajectories of the multi-particle(over than 2000 particles) were calculated. In order to expect more practical mass spectrum, the exact expressions for the collision probability was adopted. From the simulation result, we found that the exact collision probability has to be considered to analyze the materials existed in the low mass region.

서울의 Penicillinase Producing Neisseria Gonorrhoeae 발생빈도(1996)

김재홍,황동규,전재홍,김윤석,김중환,김용준,이창균,임동진,김현수,조창근,김경문,박상훈,전우형,김희성,이호정,차명수,김갑형,김형석,김석우,황지환,박병순,권오상,이민수,송기훈,성소영,이인섭,부태성 대한화학요법학회 1999 대한화학요법학회지 Vol.17 No.2

Background : In recent years, gonorrhea has been panedemic and remains one of the most commom STDs in the world, especially in developing countries. Objective & Methods: For the detection of a more effective therapeutic regimen and assessing the prevalence of PPNG, we have been trying to study the patients who have visited the VD Clinic of Choong-Ku Public Health Center in Seoul since 1980 by means of the chromogenic cephalosporin method. Results: In 1996, 139 strains of N. gonorrhoeae were isolated, among which 53(39.0%) were PPNG. Conclusion: Our results suggests that after a peak of 74.3% in 1993, the prevalence of PPNG in Seoul is gradually declining.