Hg₁-xMnxTe산화막의 홀효과에 관한 연구

오재근,최기영,송재흥,김영국,채건식,주유환,설정식,손인호,차성극,이상찬 慶南大學校 附設 基礎科學硏究所 1996 硏究論文集 Vol.8 No.-

HClO₄(pH:2) 수용액에서 양극산화 방법으로 HgMnTe(HMT)의 표면에 산화막을 형성 시켰다. 산화막의 두께는 SEM으로 측정하였으며 10㎛였다. 전류-전압 특성곡선을 얻어 산화 피크 전압으로부터 HTeO₂?, TeO?, HHgO₂? 막이 형성되었음을 알 수 있었다. 산화시키지 않은 HMT와 HClO₄수용액에서 산화시킨 HMT에 대해 Hall전압 및 자기저항을 각각 측정하였다. 홀전압과 자기저항은 HMT보다 HMT산화막에서 더 컸으며 이것은 HHgO₂? 공격자가 홀의 역할을 하고, TeO₄? 산화막은 전하의 포획도를 낮게하기 때문으로 생각할 수 있다. Anodic oxidation processes on HgMnTe surface has been studied in standard aqueous HClO₄(pH:2) solution. The 10㎛ thickness of the anodic oxide layers was measured by SEM. The Composition of the anodic oxide layers are evaluated from current-voltage(I-V) characteristic of HgMnTe Oxidation. The layers are composed of mixed oxide. ??, TeO₄, and?? in HClO₄solution. Transport properties have been investigated in HMT oxide layer made in HClO₄solution and virgin HMT samples at 300K. Hall voltage and magnetoresistance are greater in oxide layer HMT than virgin HMT. As a result, we know that the vacancy of ??in an anodic oxide layer acts as hole and the resulting oxide ?? layer exhibit a reduced degree of charge trapping and increase magnetoresistance.

Headspace-solid phase microextraction 방법에 의한 DCAA & TCAA 분석에 관한 연구

조덕희,오성근 대한상하수도학회 2003 상하수도학회지 Vol.17 No.6

Water chlorination for disinfection purposes leads to the formation of haloacetic acids (HAAs). In this study, headspace solid-phase microextraction (HSSPME) was studied as a possible alternative to liquid-liquid extrmon for the analysis of HAAs in drinking water. The method involves direct derivatization of the acids to their methyl esters without methyl tert-butyl ether (MTBE) extraction. Experimental parameters such as 2㎝-50/30㎛ divinylbenzene/carboxen/polydimethylsiloxane fiber, sulphuric acid of 1㎖, methanol of 3ml, derivatization temperature of 50T, derivatization time of 2hrs, sodium chloride salt of 10g , extraction time of 30minutes, extraction temperature of 20℃ and desorption time of lminute at 260℃ were selected in optrmal experimental conditions for the analysis of haloacetic acids. The linearity (r²) for DCAA and TCAA is 0.9981 and 0.9997 when analyte concentration ranges from 1 to 4㎍/l, respectively. The relative standard deviations (%RSD) for DCAA and TCAA were 3.5 and 2.1% for concentration of 10㎍/l (n=5), respectively. The limits of detection (LOD) were 0.05 and 0.1㎍/l. The results of HAA2 from the survey of Seongnam drinking water samples showed that the highest concentration of HAA2 (DCAA + TCAA) were 30.04㎍/l which was well within the Korean drinking water quality standard of 100㎍/l. It can be concluded that HSSPME technique with direct derivatization has a great potential for the analysis of drinking water.

접촉각 측정을 통한 Alkanethiol로 표면 처리한 은 분말의 표면 특성 연구

이길재,신승일,오성근 한국공업화학회 2004 공업화학 Vol.15 No.1

은 분말을 alkanethiol로 표면 처리한 후, alkanethiol의 탄소 개수 변화에 따른 은 입자의 표면 특성변화를 접촉각 측정을 통해 연구하였다. 이때 은 입자 표면에 alkanethiol의 흡착여부를 DRIFT (diffuse reflectance infrared fourier transform) spectrum를 통해 확인하였다. 접촉각은 Washburn 식을 바탕으로 한 liquid penetration 방법으로 측정하였고, 이 측정법의 보완을 위해 분말에 압력을 가하여 원판형태로 만들어 그 표면에서 접촉각을 측정하는 sessile drop 방법을 함께 사용하였다. 그 결과 순수한 은 입자의 물에 대한 접촉각은 두 가지 방법에 대해 각각 58°, 40° 나왔고, 다양한 탄소개수(C_(4)-C_(12))의 alkanethiol로 표면 처리한 입자는 모두 90° 이상의 결과를 얻었다. 즉 alkanethiol로 처리한 은 입자의 표면이 소수성으로 변했음을 의미한다. 여기서 처리한 alkanethiol의 탄소개수가 증가할수록 접촉각은 계속 증가했으나, 접촉각의 증가 폭은 상대적으로 점차 감소하였다. Contact angles of silver powders were measured for investigation of surface properties of silver particles as changing alkyl chain length of alkanethiol. Silver powders were modified by various alkanethiol (C4∼C12). Adsorption of alkanethiol on silver particles was confirmed by DRIFT (diffuse reflectance infrared fourier transform) spectrum. Contact angles were measured by liquid penetration method based on Washbum equation and sessile drop method on tablet of compressed powder. In result. the value of contact angles on water were 53°, 40°about two method. Contact angles of surface treated particles by alkanethiol of varied alkyl chain length were larger than 90°. Because of bonding between silver and sulfur in alkanethiol, silver surface was surrounded by alkyl groups of alkanethiol. Surface properties of silver particles were increased on hydrophobicity with alkyl chain length of alkanethiol. In comparison with increase of contact angle accordingto increase of alkyl chain length of alkanethiol. the widths of increasing contact angle were relatively decreased.

VP-16으로 성공적으로 치료된 위 Kaposi 육종 1예

양웅석,송근암,조몽,이재승,송철수,김형욱,김영민,이수봉,김태오,이성훈 대한소화기내시경학회 1999 Clinical Endoscopy Vol.19 No.4

The skin is an uncommon site of distant metastasis from any internal malignancy, and the incidence of metastatic skin lesions as the first symptom of disease is only 0.8% in patients with all systemic malignancies. Furthermore, cutaneous metastasis from adenocarcinoma of the stomach has been found to be extremely rare. A 35-year-old female patient was admitted due to multiple cutaneous nodules in her chest, abdomen, and back. A gastroendoscopic examination and biopsy was made according to the results of skin pathologic findings. Stomach and skin biopsy results revealed a signet ring cell type of adenocarcinoma. A case of gastric adenocarcinoma in which metastatic skin nodules appeared as the first sign of disease, is here in reported with a review of related literature.

러시아 농업과학기술 연구기관과 운영체체의 변화

이상덕,김종환,정남진,오대근,오성종 한국국제농업개발학회 2003 韓國國際農業開發學會誌 Vol.15 No.2

This work is dedicated to main directions of Agricultural science policy of Russia during the transition to the market economy. In this study, Russian R&D system, R&D expenditure and structure of research institutes were introduced. Especially, Studies on organizations such as RFBR : Russian Foundation for Basic Research, RFTD : Russian Fund for Technological Development, Russian Foundation for Promotion of Small Enterprises in S&T, FPP : Fund for presidential Programs, SRC : State Research Center, ISTC : International Science & Technology Center were carried out. Analysis of the problems of Agricultural Science sector of Russia shows the situation is very complicated. Despite all efforts of Government, the national institutes is still in crisis. It is clear today that without energetic and intelligent reforms, it would be impossible to implement resonable reorganization of Agricultural sector and have to strong and deserved science and technical sector in Russia.

The Preparation of Fluorine-Containing Soil Release Polymer and Its Application in Fabric Treatment Agents

김재원,하종욱,박인준,이수복,오성근 한국공업화학회 2005 응용화학 Vol.9 No.1

The fluorine-containing soil-release polymer was prepared by radical polymerization. This was used as the fabric treatment agents to improve water/oil repellency and soil release property because soil release polymer is oleophobic in air/water and hydrophilic in water. The dual function is based on interface rearrangement of the oleophobic and hydrophilic segments in air and water. The micro-phase separation by environmental response was investigated by transmission electron microscopy(TEM) and atomic force microscopy(AFM). For the evaluation of the water/oil repellency and soil release property, we used the AATCC test method.

Ether-free polymeric anion exchange materials with extremely low vanadium ion permeability and outstanding cell performance for vanadium redox flow battery (VRFB) application

Cha, Min Suc,Jo, Sang Woo,Han, Seung Hui,Hong, Soo Hyun,So, Soonyong,Kim, Tae-Ho,Oh, Seong-Geun,Hong, Young Taik,Lee, Jang Yong Elsevier 2019 Journal of Power Sources Vol.413 No.-

<P><B>Abstract</B></P> <P>Ether-free poly(<I>p</I>-phenylene)-based anion exchange membrane materials with outstanding vanadium ion blocking properties are reported. The synthesized ionomers with a rigid backbone structure show small dimensional variations despite the high ion exchange capacities. Among the synthesized membranes, the QPPP-2 membrane with ion exchange capacity of 2.1 meq·g<SUP>−1</SUP> exhibits high anion (OH<SUP>−</SUP>, SO<SUB>4</SUB> <SUP>2−</SUP>, and Cl<SUP>−</SUP>) conductivity. The QPPP-2 membrane shows an extremely low diffusion coefficient (2.12 × 10<SUP>−9</SUP> cm<SUP>2</SUP> min<SUP>−1</SUP>) for VO<SUP>2+</SUP>, which is much lower than that of Nafion 115 (2.88 × 10<SUP>−6</SUP> cm<SUP>2</SUP> min<SUP>−1</SUP>), indicating the vanadium ion blocking property of QPPP-2. Moreover, the chemical and operational stabilities of the membranes are investigated <I>via</I> 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 vanadium redox flow battery single cell assembled with the QPPP-2 membrane exhibits a coulombic efficiency of 99%, voltage efficiency of 87%, and energy efficiency of 86% during 100 cycles at 80 mA cm<SUP>−2</SUP>. The excellent chemical, morphological, and electrochemical properties of the QPPP-2 membrane make it suitable for use in vanadium redox flow battery.</P> <P><B>Highlights</B></P> <P> <UL> <LI> AEMs are fabricated by a Ni(0)-catalyzed cross-coupling reaction. </LI> <LI> The synthesized ionomers indicated excellent dimensional and chemical stability. </LI> <LI> Ether-free polymeric AEMs showed extremely low vanadium ion cross over. </LI> <LI> The performance of developed AEM showed high EE (87%) with high capacity retention. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

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>

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>

Preparation and characterization of BaTiO3 particles coated with yttrium compound

Seong-Geun Oh,Young-Ho Lee 한양대학교 세라믹연구소 2004 Journal of Ceramic Processing Research Vol.5 No.2

Barium titanate (BaTiO3) particles were homogeneously coated with yttrium compound by the decomposition of yttrium nitrate with urea in aqueous solution. The morphologies of the yttrium compound- coated BaTiO3 particles were controlled by varying the initial concentration of yttrium nitrate for a fixed reaction temperature and time. The relationship between the initial yttrium concentration and the coating layer thickness was confirmed by transmission electron microscopy (TEM)images. Electron probe microanalyzer (EPMA) and XRD data showed that the BaTiO3 particles were homogeneously coated with yttrium compound.