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Bora Jeong(정보라),Myeung-jin Lee(이명진),Bora Ye(예보라),Seung-Yeop Chun(전승엽),Taewook Kim(김태욱),Hong-Dae Kim(김홍대) 한국에너지기후변화학회 2021 한국에너지기후변화학회 학술대회 Vol.2021 No.5
Regulation of air pollution (e.g., EURO 6, TIER 3) has been strengthened in many jurisdictions due to the occurrence of problems such as particulate matter (PM). At present, selective catalytic reduction (SCR) is the most effective method to control NOX emissions. Industrial V2O5-WO3/TiO2 catalysts (usually containing 0.5–3wt% V2O5 and 5–10wt% WO3) exhibit high de-NOX efficiency, and excellent resistance to sulfur (SO2) and H2O. Nevertheless, they also have several disadvantages such as high and narrow effective temperature range(300–400°C), and a tendency to oxidize SO2 to SO3. Therefore, SCR catalysts with high de-NOX efficiency at lower operating temperatures are required in order to obtain economic benefits and reduced energy consumption. Typically, silica has a good candidate to improve catalytic properties such as led to generation acid site, specific surface area, thermal stability. In this reason, enhanced the SCR catalyst property by using colloidal silica and glass fiber. The aim of this work, we confirmed the effect of silica on the chemi-physical properties and de-NO<sub>X</sub> efficiency of vanadium based catalyst. These synthesized catalysts were analyzed by BET, TPD, FT-IR and catalytic performances using fixed-bed reactor in the range of 200-450°C.
목재접착에서 아미노 수지 접착제의 분자량이 경화거동, 접착층 특성 및 접착력에 미치는 영향
정보라 ( Bora Jeong ) 한국목재공학회 2020 한국목재공학회 학술발표논문집 Vol.2020 No.1
As a part of understanding the adhesion in wood, this study investigated impact of the synthesis method of urea-formaldehyde (UF) and melamine-urea-formaldehyde (MUF) resins to their cohesive and interphase features, and adhesion in bonding wood products. UF resins at two final F/U molar ratios (1.0 and 1.2) with low-viscosity (LV) and high-viscosity (HV), respectively, were mixed at five different blending ratios of 100:0, 75:25, 50:50, 25:75, and 0:100 to obtain different viscosities. In addition, MUF resin at three additional levels (5, 10 and 20%) was simultaneously reacted with urea and formaldehyde to obtain MUF-A resins, while melamine at the same levels was initially reacted with formaldehyde and then with urea to prepare MUF-B resins. The results showed that the UF resins as the viscosity during the condensation phase increased, the MW increased while the gelation time and the low molecular weight fraction decreased. The UF resins with F/U molar ratio of 1.2 had higher MW and activation energy than those with F/U molar ratio of 1.0. Isoconversional analysis showed that the 1.0 F/U molar ratio resin went through a multiple-step process in their curing mechanism, unlike the 1.2 F/U molar ratio resin, whose cohesion during bond formation was likely affected by the higher F content. As the MW increased, the resins with 1.0 and 1.2 F/U molar ratios exhibited the highest maximum storage modulus (E′max), greatest depth of resin penetration, thinnest bond-line, and highest adhesive strength at apparent Mw of 2000-2400 g/mol for the 1.0 F/U molar ratio resins (according to mixing ratios LV/HV = 50:50 and 25:75) and 3500- 4500 g/mol for the 1.2 F/U molar ratio resins (again according to mixing ratios LV/HV = 50:50 and 25:75). MUF resins as the melamine content increased, MW, curing peak temperature, activation energy, bondline thickness, E’max, and adhesion strength of wood products increased. These results indicated that the cohesive features of these resins mainly affected the adhesion strength in wood products while the interphase features had a partial contribution to the adhesion. - 7
바나듐 담지된 그래핀 나노복합체를 첨가한 SCR 촉매의 제조 및 활성 평가
정보라,이희수,김억수,김홍대,Jeong, Bora,Lee, Heesoo,Kim, Eok-Soo,Kim, HongDae 한국결정성장학회 2015 韓國結晶成長學會誌 Vol.25 No.6
질소산화물 ($NO_X$)은 고정원(화력발전소, 산업시설) 및 이동원(자동차, 선박) 등에서 배출되어지며, 발암물질 및 광화학 스모그의 주범으로 작용하고 있다. 선택적 촉매 환원법(SCR)은 $NO_X$를 제거하는 가장 효율적인 방법이며, 상업용으로 사용되어지는 $V_2O_5-WO_3/TiO_2$계 촉매에서 $V_2O_5$ 함량은 0.5~3 wt%, $WO_3$ 함량은 5~10 wt%이다. 촉매 성분 중 $V_2O_5$의 경우 $NO_X$ 환원 반응을 통해 촉매 작용을 촉진시키지만, 과량으로 첨가될 경우, $SO_2$에서 $SO_3$로의 산화 반응을 증가시킨다. 본 연구에서는 높은 탈질 효율을 유지시킴과 더불어, 바나듐의 함량을 줄이기 위하여, 그래핀을 바나듐 담지 matrix로 사용하여 나노복합체를 합성하였으며, 합성된 나노복합체를 첨가하여 Honeycomb형 1 inch SCR 촉매를 제조하였다. 제조된 SCR 촉매는 XRD(X-ray Diffraction), XRF(X-ray Fluorescence Spectrometer), BET(Brunauer, Emmett & Teller) 등의 분석을 통해 물성 평가를 진행하였으며, Micro Reactor(MR)를 이용하여 활성평가를 진행하였다. 그 결과, 촉매 상용 운전 온도인 $350^{\circ}C$에서 나노복합체가 첨가된 SCR 촉매의 탈질 효율은 77.1 %로 상용촉매의 탈질 효율인 77.8 %와 유사한 효율을 나타내는 것을 확인하였다. Nitrogen oxides ($NO_X$) was emitted from flue gas of stationary sources and exhaust gas of mobile sources, can leads to various environments problems. Selective Catalysts Reduction (SCR) is the most effective $NO_X$ removal system. Commercial $V_2O_5-WO_3/TiO_2$ catalysts, usually containing $V_2O_5$ 0.5~3 wt%, $WO_3$ 5~10 wt%, and $V_2O_5$ is active in the reduction of $NO_X$ but also in the desired oxidation of $SO_2$ to $SO_3$. To reduce the amount of vanadium, using graphene matrix supported vanadium to synthesize nanocomposite. Then, we fabricated to 1 inch honeycomb type of SCR catalysts adding graphene-vanadium nanocomposite. The chemical-physical characteristics and the catalytic activity were performed by XRD, XRF, BET and Micro-Reactor (MR). As a result, the De-NOX performance was showed, similar to the commercial catalyst activity as 77.8 % and using nanocomposite catalyst as 77.1 % at $350^{\circ}C$.
저유전율을 가지는 D-Glass Fiber의 제조 및 특성
정보라,이지선,이미재,임태영,이영진,전대우,신동욱,김진호,Jeong, Bora,Lee, Ji-Sun,Lee, MiJai,Lim, Tae-Young,Lee, Youngjin,Jeon, Dae-Woo,Shin, Dongwook,Kim, Jin-Ho 한국재료학회 2018 한국재료학회지 Vol.28 No.4
General D-glass(Dielectric glass) fibers are adaptable to PCBs(Printed circuit boards) because they have a low dielectric constant of about 3.5~4.5. However, very few papers have appeared on the physical characteristics of D-glass fibers. D-glass fibers were fabricated via continuous spinning process using bulk D-glass. In order to fabricate the D-glass, raw materials were put into a Pt crucible, melted at $1650^{\circ}C$ for 2 hrs, and then annealed at $521{\pm}10^{\circ}C$ for 2 hrs. We obtained transparent clear glass. The transmittance and adaptable temperature for spinning of the bulk marble glass were characterized using a UV-visible spectrometer and a viscometer. Continuous spinning was carried out using direct melting spinning equipment as a function of the fiberizing temperature in the range of $1368^{\circ}C$ to $1460^{\circ}C$, while the winder speed was between 100 rpm and 200 rpm. We investigated the physical properties of the D-glass fibers. The average diameters of the glass fibers were measured by optical microscope and FE-SEM. The average diameters of the D-glass fibers were 21.36 um at 100 rpm and 34.06 um at 200 rpm. The mechanical properties of the fibers were confirmed using a UTM(Universal materials testing machine). The average tensile strengths of the D-glass fibers were 467.03 MPa at 100 rpm and 522.60 MPa at 200 rpm.
정보라,이지선,이미재,임태영,이영진,전대우,신동욱,김진호,Jeong, Bora,Lee, Ji-Sun,Lee, MiJai,Lim, Tae-Young,Lee, Youngjin,Jeon, Dae-Woo,Shin, Dongwook,Kim, Jin-Ho 한국재료학회 2017 한국재료학회지 Vol.27 No.1
E-glass (electrical glass) fiber is the widely used as a reinforced composite material of PCBs (printed circuit boards). However, E-glass fiber is not stable because it has a dielectric constant of 6~7. On the other hand, D-glass (dielectric glass) fiber has a low dielectric constant of 3~4.5. Thus, it is adaptable for use as a reinforcing material of PCBs. In this study, we fabricated D-glass compositions with low dielectric constant, and measured the electrical and optical properties. In the glass composition, the boron content was changed from 9 to 31 wt%. To confirm the dependence of the dielectric constant on melting properties, D-glass with 22 wt% boron was melted at $1550^{\circ}C$ and $1650^{\circ}C$ for 2hrs. The glass melted at $1650^{\circ}C$ had a lower dielectric constant than the glass melted at $1550^{\circ}C$. Therefore, the D-glass with boron of 9~31 wt% was fabricated by melting at $1650^{\circ}C$ for 2hrs, and transparent clear glass was obtained. We identified the non-crystalline nature of the glass using an XRD (x-ray diffractometer) graph. The visible light transmittance values depending on the boron contents were measured and found to be 88.6 % ~ 82.5 %. Finally, the dielectric constant of the D-glass with 31 wt% boron was found to have decreased from 4.18 to 3.93.
Geumyeon Lee(이금연),Bora Jeong(정보라),Hangyu Im(임한규),Hong-Dae Kim(김홍대),Teawook Kim(김태욱) 한국에너지기후변화학회 2021 한국에너지기후변화학회 학술대회 Vol.2021 No.5
Nitrogen oxides (NOx) discharged from stationary sources such as industrial facilities, cement kilns and fossil fuel power stations, which are recognized as place where it occurs severe environmental pollution problems causing nitrate particulate and photochemical smog. Because the regulations related with NOx emission has been become more stringent, denitration catalysts are required following: high performance and wide active temperature for a variety of applications. V2O5-WO3/TiO2 catalysts, commercially used selective catalytic reduction (SCR) catalysts, have relative narrow and active temperature range of 350-450°C. This study is investigated to extend to wide operating temperature range of 240-450°C. The catalysts are prepared by co-precipitation of V-W-Ti which briefly described as V2O5, WO3 and Ti supported on TiO2 powder. Through method of co-precipitation, the formed functional group increase active sites. Consequently synthesized catalyst with co-precipitation shows the high NOx removal efficiency in a wide active temperature range of 240-450°C by controlling active sites.