The Microencapsulation of Eicosane with Interfacial Polymerization of Polyurea

Bona CHOI,Jeong Soo KIM 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2

Microencapsulation of Eicosane with Suspension and Emulsion Copolymerizations of PMMA

Bona Choi(최보나),Jeong Soo Kim(김정수) 한국고분자학회 2019 폴리머 Vol.43 No.1

파라핀계 상변환 축열재의 응용 확대를 위해 모델 물질로 탄소수 20개인 아이코산을 택하고 이를 분산중합에 의해 미세캡슐화한 후 그 축열 거동을 관찰하였다. 메틸 메타크릴레이트(MMA)을 기본 단량체로 하고 유화중합법과 현탁중합법이 사용되었으며, 공단량체로는 메틸 메타크릴산(MAA), 에틸 메타크릴레이트(EMA), 부틸 메타크릴레이트(BMA)가 사용되었다. 미세캡슐화 방법을 달리하는 인자로는 중합법, 공단량체의 종류 및 무게분율, 가교제의 종류 및 투입량이 있다. 미세캡슐화 입자의 모폴로지, 입자 크기, 미세피낭 효율, 열적 거동 등이 관찰되었으며, 이들의 관찰은 FTIR, SEM, DSC, TGA를 통해 이루어졌다. Eicosane, which is a saturated linear hydrocarbon with 20 carbons, was selected as a core phase change material (PCM) for microencapsulation with dispersion polymerizations. The microencapsulation reactions were carried out by emulsion and suspension copolymerization of methyl methacrylate (MMA) with comonomers such as methacrylic acid (MAA), ethyl methacrylate (EMA), and butyl methacrylate (BMA). The preparation methods were diversified through varying different factors, such as polymerization method, the kinds and composition of comonomers, and crosslinking agents. The morphology, particle sizes, and thermal properties including encapsulation efficiency of the prepared microcapsules were analyzed using Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis.

Silver nanowire catalysts on carbon nanotubes-incorporated bacterial cellulose membrane electrodes for oxygen reduction reaction.

Kim, Bona,Choi, Youngeun,Cho, Se Youn,Yun, Young Soo,Jin, Hyoung-Joon American Scientific Publishers 2013 Journal of Nanoscience and Nanotechnology Vol.13 No.11

<P>Silver nanowires have unique electrical, thermal and optical properties, which support their potential application in numerous fields including catalysis, electronics, optoelectronics, sensing, and surface-enhanced spectroscopy. Especially, their application such as catalysts for alkaline fuel cells (AFCs) have attracted much interest because of their superior electrical conductivity over that of any metal and their lower cost compared to Pt. In this study, multiwalled carbon nanotubes (MWCNTs)-incorporated bacterial cellulose (BC) membrane electrode with silver nanowire catalyst was prepared. First, acid-treated MWCNTs were incorporated into BC membranes and then freeze-dried after solvent exchange to tert-butanol in order to maintain the 3D-network macroporous structure. Second, silver nanowires synthesized by polyol process were introduced onto the surface of the MWCNTs-incorporated BC membrane through easy vacuum filtration. Finally, thermal treatment was carried out to confirm the effect of the PVP on the silver nanowire catalysts toward oxygen reduction reaction. The electrode with thermally treated silver nanowire had great electrocatalytic activity compared with non-treated one. These results suggest that the MWCNTs-incorporated BC electrode with silver nanowire catalysts after thermal treatment could be potentially used in cathodes of AFCs.</P>

셰일 저류층에서 케로젠, GOR 변화에 따른 속도 변화 및 AVO 반응 분석

최준환 ( Junhwan Choi ),이재욱 ( Jaewook Lee ),변중무 ( Joongmoo Byun ),김보나 ( Bona Kim ),김소영 ( Soyoung Kim ) 한국지구물리·물리탐사학회 2016 지구물리와 물리탐사 Vol.19 No.1

Recently, the studies about rock physics model (RPM) in shale reservoir are widely performed. In shale reservoir, the degree of the maturity can be estimated by kerogen and GOR (Gas-Oil Ratio). The researches on the rock physics model of shale reservoir with the amount of kerogen have been actively carried out but not with GOR. Thus, in this study, we analyzed the changes in seismic velocity and density, and AVO (Amplitude Variation with Offset) response depending on changes in GOR and the amount of kerogen. Since the shale consists of plate-like particles, it has vertical transverse isotropy (VTI). Therefore we estimated the seismic velocity and density by using Backus averaging method and analyzed AVO responses based on these estimated properties. The results of analysis showed that the changes in the velocity with the GOR variation are small but the velocity changes with the variation in kerogen amount are relatively larger. In case, GOR 180 (Litre/Litre) which is boundary between heavy oil and light oil, when volume fraction of kerogen increased from 5% to 35%, the P-wave velocity normal to the layering increased 51%. That is, it helps estimating maturity of kerogen through the velocity. Meanwhile, when rates of oil-gas mixture are large, the effect of GOR variation on the velocity change became larger. In case volume fraction of kerogen is 5%, the P-wave velocity normal to the layering was estimated 1.46 km/s2 in heavy oil (GOR 40) but 1.36 km/s2 in light oil (GOR 300). The AVO responses analysis showed class 4 regardless of the GOR and amount of kerogen because variation of poisson’s ratio is small. Therefore, shale reservoir has possibility to have class 4.

Free-standing nitrogen-doped reduced graphene oxide anode for lithium-ion batteries.

Park, Hyun Ho,Choi, Youngeun,Kim, Bona,Yun, Young Soo,Jin, Hyoung-Joon American Scientific Publishers 2013 Journal of Nanoscience and Nanotechnology Vol.13 No.12

<P>Graphenes have been considered suitable candidate materials for electrodes of energy storage devices such as lithium-ion batteries (LIBs) because of their outstanding mechanical, thermal and electrical properties. However, there are problems when using these carbon materials for electrodes because of their low electrochemical performance. In this work, to improve the electrochemical performances of graphenes, free-standing nitrogen-doped reduced graphene oxides (FNRGOs) were prepared as an anode for LIBs using a facile vacuum filtration method and thermal annealing at different temperatures. X-ray diffraction and X-ray photoelectron spectroscopy were employed to characterize the prepared samples, and then their electrochemical performance was investigated by galvanostatic charge/discharge (GCD) tests. GCD tests revealed that FNRGO prepared from thermal annealing at 500 degrees C exhibited good initial reversible capacity (502 mA h/g at 50 mA/g (0.14 C)) and enhanced cycle stability (capacity retention of 90.5% after 50th cycles at 100 mA/g (0.27 C), which demonstrated that FNRGOs were suitable candidates as anodes for LIBs.</P>

Induction of Serum Amyloid A Genes Is Associated with Growth and Apoptosis of HC11 Mammary Epithelial Cells

KHO, Yoonjung,KIM, Sungchan,YOON, Byung Sun,MOON, Jai-Hee,KIM, Bona,KWAK, Sungwook,WOO, Junghee,OH, Sejong,HONG, Kichang,KIM, Saehun,KIM, Hyunggee,YOU, Seungkwon,CHOI, Yunjaie Japan Society for Bioscience, Biotechnology, and A 2008 Bioscience, Biotechnology, and Biochemistry Vol.72 No.1

<P>In this study, we examined the expression and functions of serum amyloid A (SAA) isoforms during apoptosis of HC11 mammary gland epithelial cells. Expression of SAA mRNAs and apoptosis were increased in HC11 cells by serum withdrawal and gradually decreased upon the addition of serum, or epidermal growth factor (EGF). TNFα treatment of HC11 cells also induced expression of SAA genes, and the effect on SAA1 and SAA2 expression was suppressed by treatment with MG132, and in cells transfected with a dominant negative mutant form of IκBα. Similar results were observed in response to interleukin-1 (IL-1), IL-6 and interferon γ (IFNγ). Furthermore, overexpression of the SAA1 and SAA2 isoforms suppressed growth and accelerated apoptosis of HC11 cells by increasing caspase 3/7 and caspase 8 activities, but the apoptotic effect of tumor necrosis factor α (TNFα) on HC11 cells was not enhanced. We found that expression of <I>SAA1</I> and <I>SAA2</I>, but not <I>SAA3</I>, was regulated by an NFκB-dependent pathway, and that overexpression of SAA isoforms accelerated the apoptosis of HC11 cells.</P>

방사성폐기물 처분시설 부지특성 조사 및 평가 규제요건(안)

현승규(Seung Gyu Hyun),심택모(Taekmo Shim),진소범(Sobeom Jin),최호선(Hoseon Choi),양준모(Junmo Yang),최강룡(Kang Ryong Choi),박선종(Sunjong Park),이세현(Sei Hyun Lee),우현동(Hyeon Dong Woo),박보나(Bona Park),배재석(Jae Seok Bae) 대한지질학회 2021 대한지질학회 학술대회 Vol.2021 No.10

방사성폐기물의 지질학적 처분은 공학적 방벽 및 천연방벽의 종합적인 조합에 의해 이루어지며, 이를 위해서는 처분시설이 위치하는 부지에 대한 부지특성화를 통해 처분시설 설계, 장기안전성 평가 등을 통해 처분시설의 안전성이 확인된다. 이와 같이 고준위방사성폐기물의 심층 처분 안전성 평가와 관련한 부지특성 조사 및 평가에 대한 규제요건은 처분프로그램의 이행 단계에 적합하게 되어야 한다. US NRC 10 CFR Part 60(Disposal of High-Level Radioactive Wastes in Geological Repositories)는 인허가 이전 검토, 건설허가 단계 등에서 처분시설 부지의 특성에 대한 요건을 제시하고 있으며, 이에 따라 US NRC는 DOW가 1988년에 제출한 Site Characterization Plan을 검토하여 NUREG-1347 (NRC Staff Site Characterization Analysis of the Department of Energy’s Site Characterization Plan, Yucca Mountain Site, Nevada)을 발행하였다. IAEA Specific Safety Requirements No. SSR-5 (Disposal of Radioactive Waste) 요구사항 2는 ‘규제기관은 방사성 폐기물을 위한 서로 다른 유형의 처분시설 개발을 위한 규제 요건을 수립하여야 하며, 다양한 단계의 인·허가 과정에 대한 요건에 부합되는 절차를 수립하여야 한다.’고 정하고 있다. 그러나 현재 원자력안전법 체계 내에서는 고준위방사성폐기물 처분시설 부지특성 조사 및 평가에 관한 상세 요건이 마련되지 않은 실정이다. 2018년 4월부터 수행된 본 연구[고준위방사성폐기물 처분시설 부지특성 평가 및 조사를 위한 기준개발]의 목표 중 하나인 고준위방사성폐기물 처분시설 부지특성보고서 작성지침 고시(안) 개발 관련하여 부지특성 현황, 처분시설의 설계·건설·운영·폐쇄, 장기처분안전성 평가 측면에서 요구되는 부지특성 분야별(지질학적 및 지구물리학적 특성, 수리지질학적 특성, 수리지화학적 특성, 암반공학적 특성, 암반의 열적 특성, 암반 내 오염물질 이동특성, 생태계 특성) 조사 및 평가에 대한 규제요건(안)을 도출하였다.