벽면에서의 촉매 효과를 고려한 우주쓰레기의 궤적 예측 프로그램 개발

박성현(Seong hyeon Park),박기수(Gisu Park) 한국항공우주학회 2016 한국항공우주학회 학술발표회 논문집 Vol.2016 No.4

극초음속으로 재진입하는 우주쓰레기의 생존성 및 궤적 예측은 지난 수십 년 동안 연구되어 왔다. 공력에 의한 열(heat) 계산에 있어서 NASA의 ORSAT프로그램 및 ESA의 SCARAB프로그램과 같은 기존의 재진입 해석 프로그램들은 평형 경계층 및 벽면에서의 super-catalytic 가정을 사용한 Fay and Riddell 이론을 접목하였다. 그러나 이러한 가정들은 공력가열에 의한 열을 크게 예측하므로 정확하지 않다. 본 연구에서는 Goulard가 제안한 비평형 열 계산식을 접목하여 super-catalytic 효과와 non-catalytic 효과를 비교해보았다. Non-catalytic 효과인 경우에 우주쓰레기가 더 오래 살아남는 것을 확인하였다. 따라서 우주쓰레기 생존성 예측에 있어서 벽면에서의 촉매 현상은 중요하다. Survivability and trajectory estimation of reentry space debris have been carried out over the past few decades. In aerodynamic heat calculation, the reentry analysis programs such as ORSAT by NASA, and SCARAB by ESA, use Fay and Riddell’s formula which has several assumptions of equilibrium boundary layer and a super-catalytic surface. However, these assumptions are inaccurate because they overestimate aerodynamic heating from the surface. In this paper, Goulard formula is used to calculate non-equilibrium aerodynamic heating and to compare super-catalytic effect with non-catalytic effect. In the modelling of a non-catalytic effect, it is shown that the space debris survivability was higher than that of the super catalytic effect. Therefore, the catalytic effect on the wall is important to estimate space debris survivability.

Synergistic effect of –COOH and Zr(IV) with a short distance in Zr-MOFs for promoting utilization of H2O2 in oxidative desulfurization

Zhaoyang Qi,Yan Wang,Changshen Ye,Jie Chen,Ting Qiu 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.111 No.-

The effectiveness of the catalytic oxidative desulfurization (CODS) process crucially depends on the catalyticactivity of the catalyst and the utilization of oxidizing agent. Catalyst with multiple active sites is aneffective method to improve the CODS effectiveness. The Zr(IV) and –COOH-containing metal–organicframework, UiO-66-(COOH)2, was synthesized and used as an active and recyclable catalyst for CODS. The UiO-66-(COOH)2 shows higher catalytic activity and H2O2 utilization in the CODS process thanUiO-66/–COOH, UiO-66, and H2BDC. And the high catalytic performance is derived from the synergisticeffect between the Zr(IV) open site and free –COOH functionality within the framework. Experimentalanalysis and DFT calculations results indicate that the synergistic effect, which changes the reaction pathand protects the *O2 – radical, is a very effective strategy to promote desulfurization efficiency and the utilizationefficiency of H2O2. In addition, it is essential to highlight that the active-site distance also has asignificant influence on the effectiveness of CODS. This research may provide a new avenue for improvingthe CODS performance.

Synthesis of Carbon Materials with Hierarchical Porosity and Catalytic Effects

권예림,유주현,김지만 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1

Secondary batteries are becoming important with increased use of portable electronic devices. Li-ion battery is the most commonly used but it shows the limitation of capacity for electric vehicle. Li-S battery is a one of the promising alternative to Li-ion battery. It has high theoretical energy density, low cost, eco-friendliness and safety. But polysulfide anions are dissolved in the repetitive charging and discharging so it makes the capacity decrease, which is called shuttle effect. To minimize shuttle effect, we synthesized carbon materials with porosity and metal nanoparticles. Ordered mesoporous carbon (OMC) has high thermal and chemical stability, high surface area and high pore volume. We synthesized the OMC materials with micropores by introducing silica nanoparticles and loaded metal nanoparticles as the catalytic factor. The materials were characterized by X-ray diffraction(XRD), N2-sorption, scanning electron microscope(SEM), and energy dispersive X-ray(EDX).

Enhanced Carbon Materials with Physical Block and Catalytic Effects for Li-S Batteries

권예림,유주현,문현지,김수진,김지만 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-

Nowadays portable electronic devices are used widely and these are indispensable part of everyday life. It makes secondary batteries important for future innovation. Li-S battery is becoming one of the promising batteries. It has high theoretical energy density and low cost. Also it is eco-friendly and safe. However, there is the primary problem to be commercialized, which is shuttle effect. It makes capacity decrease and internal resistance increase. To minimize the shuttle effect, we modified ordered mesoporous carbon(OMC) materials. OMC has high thermal and chemical stability, high surface area and high pore volume. First, we synthesized the OMC materials with micropore by introducing silica nanoparticles. We expected that polysulfides with long chain could be blocked due to the small pore size. In the second place, we loaded metal nanoparticles on the OMC. Nanoparticles of platinum could catalyze the reaction of polysulfides so dissolved polysulfides could be trapped.

Synthesis of pompon-like ZnO microspheres as host materials and the catalytic effects of nonconductive metal oxides for lithium-sulfur batteries

송현기,서석호,박형훈,장다은,김지훈,김형진 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.99 No.-

Lithium-sulfur batteries have attracted tremendous attention as promising next-generation batterysystems because of their high theoretical specific capacity and cost-competitiveness. Nevertheless, thecommercialization of sulfur-based cathodes has been limited by substantial problems such as theinsulating property of S8/Li2S, low active material utilization, and inevitable dissolution of lithiumpolysulfides into organic electrolytes. Among the materials used to solve these problems, metal oxidematerials have attracted attention because of their strong chemical/physical interactions withpolysulfides and catalytic effect. However, most studies include strategies to add electron networksor synthesize metal oxides into nanosize because of the nonconductive properties of metal oxides. Herein, to demonstrate the intrinsic effect of metal oxides, pompon-like ZnO microspheres (p-ZnO) areemployed by a hydrothermal method and subsequent calcination for a sulfur host (p-ZnO/S) for thefirsttime. The composite of p-ZnO/S significantly enhanced the sulfur utilization and rate capability withoutadditional efforts to improve the electrical conductivity. In addition, the decrease of reaction resistanceand charge-transfer resistance was shown in electrochemical impedance spectroscopy (EIS) andgalvanostatic intermittent titration technique (GITT) results. Furthermore, the catalytic effect isdescribed by analyzing the lithium ion diffusion coefficient and verifying the chemical compositionchange on the cathode surface during the sulfur redox reaction.

졸-겔법에 의한 SiO₂-TiO₂ 박막의 초친수성

박민정,이경석,강종봉,문종수,Park, Min-Jung,Lee, Kyoung-Seok,Kang, Jong-Bong,Mun, Chong-Soo 한국재료학회 2007 한국재료학회지 Vol.17 No.3

[ $TiO_{2}-solution$ ] was aaded in $SiO_{2}-solution$ by various composition. $SiO_{2}-TiO_{2}$ thin films were obtained by the dip-coating method on the $SiO_{2}$ glass substrates, and then heat-treated at various temperature. Nano-size $TiO_{2}$ particles dispersed $SiO_{2}-TiO_{2}$ films showed absorption peak by quantum size effect at short wavelength region $350{\sim}400nm$, which made them good candidates for non-linear optical materials and photo-catalytic materials. The thickness of $SiO_{2}-TiO_{2}$ films were $300{\sim}430nm$. The contact angle of $SiO_{2}-TiO_{2}$ films for water was $5.3{\sim}47.9^{\circ}$, and therefore it is clear that $SiO_{2}-TiO_{2}$ films have super hydrophilic properties and the self-cleaning effects.

Study on ultra-high sensitivity piezoelectric effect of GaN micro/nano columns

Haixia Zhang,Xiaodong Hu,Hua Zong,Jianbo Fu 나노기술연구협의회 2019 Nano Convergence Vol.6 No.33

High-quality GaN micro/nano columns were prepared with self-organized catalytic-free method. Young’s modulus of GaN nanocolumns were measured under both compressive stress and tensile stress. It was found that the Young’s modulus decreases with the increasing of nanocolumn diameter due to the increase of face defect density. Furthermore, we measured the piezoelectric properties and found that there was a 1000-fold current increase under a strain of 1% with a fixed bias voltage of 10 mV. Based on the Schottky Barrier Diode model, we modified it with the effect of polarization charge, image charge and interface state to analyze the experiment results which reveals that the strong piezopolarization effect plays an important role in this phenomenon. Therefore, the GaN nanocolumns has a great prospect to be applied in high-efficiency nanogenerators and high-sensitivity nanosensors.

Smart and recyclable Fe3O4@APTES-β-CD nanoparticles with supramolecular host-guest synergistic enhancement effect for 2-chloro- 4-nitrophenol removal

Jinrong Jiang,Xuze Hu,Meiying Huang,Guoxin Lan,Lian Ma,Jiahui Lin,Junsheng Qi,Changjun Zou 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.127 No.-

A facile and efficient strategy was introduced to prepare p-tolylsulfonyl-b-cyclodextrin (TsO-b-CD). Subsequently, the smart and recyclable Fe3O4@APTES-b-CD nanoparticles were prepared via betweenFe3O4@APTES and TsO-b-CD. And then, the structures of TsO-b-CD and Fe3O4@APTES-b-CD were characterizedand analyzed. Finally, the Fe3O4@APTES-b-CD nanoparticles was utilized as a heterogeneousFenton-like catalyst. The catalytic performance of Fe3O4@APTES-b-CD for 2-chloro-4-nitrophenol (4-C-2-NP) were assessed and studied. Accordingly, the degradation process of 4-C-2-NP fitted the pseudofirst-order kinetics model. In the meantime, the catalytic activity of Fe3O4@APTES-b-CD was higher thanthat of Fe3O4@APTES-a-CD or Fe3O4@APTES-c-CD. More importantly, the Fe3O4@APTES-b-CD possessedgood regeneration and reuse ability. In addition, the possible reaction route and degradation mechanismwere proposed with synergistic effects. Consequently, the Fe3O4@APTES-b-CD can potentially serve as asmart and recyclable heterogeneous Fenton-like catalyst.

Investigation of ambient aerosol effective density with and without using a catalytic stripper

Lin, Yue,Bahreini, Roya,Zimmerman, Stephen,Fofie, Emmanuel A.,Asa-Awuku, Akua,Park, Kihong,Lee, Seung-Bok,Bae, Gwi-Nam,Jung, Heejung S. Elsevier 2018 Atmospheric environment Vol.187 No.-

<P><B>Abstract</B></P> <P>Size-resolved effective densities of ambient aerosols in Riverside, CA were determined over 4 periods during 2015–2016. A DMA-CPMA-CPC technique was used to measure effective density for particles with selected diameters of 50, 70, 101 and 152 nm. A catalytic stripper (CS) was used alternately to remove the volatile fraction of aerosol before density measurements. Aerosol non-refractory composition measurement was conducted in June 2016 campaign to understand the effect of chemical composition on particle density. The average densities for particles over all the measurement campaigns over BP mode (i.e. bypassing the CS) were 1.17 g/cm<SUP>3</SUP> at 50 nm and 1.25–1.28 g/cm<SUP>3</SUP> at 70, 101 and 152 nm. The average density after CS conditioning (CS mode) showed a decreasing trend from 1.22 g/cm<SUP>3</SUP> to 1.04 g/cm<SUP>3</SUP>, with increase in the selected size, and a mass fractal dimension (D<SUB>f</SUB>) of 2.85. Both the BP and CS mode particles showed the lowest effective density at 6–9 am and highest density at 11 a.m.-3 pm. The diurnal variation of density for both modes became more intensive as particle size increased. The variation was also more intense for the CS mode compared to the BP mode. Organic aerosol and ammonium nitrate mass in the size range of density measurements correlated well positively (R<SUP>2</SUP> = 0.78) and negatively (R<SUP>2</SUP> = 0.62), respectively with BP mode effective density. The study provides an update to the aerosol density profiles of a well-known receptor site (Riverside, CA) and investigates the transformation of particles in different seasons. The effective density profiles will be used in a follow-up study to better estimate the respiratory-deposited ambient aerosol mass.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Seasonal variation of ambient particle effective densities. </LI> <LI> Size dependent refractive particle effective densities. </LI> <LI> Influence of particle chemical composition on diurnal variation of particle effective density. </LI> </UL> </P>

V2O5-P2O5계 유리의 B2O3 치환에 따른 구조 및 물성변화 (2)

최수연 ( Su Yeon Choi ),김영석 ( Young Seok Kim ),김종환 ( Jong Hwan Kim ),정재엽 ( Jae Yeop Jung ),김일구 ( Il Gu Kim ),박현준 ( Hyun Joon Park ),배종성 ( Jong Sung Bae ),류봉기 ( Bong Ki Ryu ) 대한금속재료학회(구 대한금속학회) 2015 대한금속·재료학회지 Vol.53 No.3

In this study, we verify the relationship among the catalytic effect, electrical conductivity, and structure of vanadium borophosphate glasses that have a coincidence of BO3 and BO4 and a coincidence of V4+ and V5+. We prepared vanadium borophosphate glasses with various compositions, given by 70V2O5- xB2O3-(70-x) P2O5(x=0-10mol%), and analyzed the catalytic effect, electrical conductivity, FT-IR spectroscopy, X-ray photoelectron spectroscopy, thermal properties, density, and molar volume. In V2O5-P2O5 binary glasses, the electrical conductivity increased from 0. 4073 × 10?7/Ω to 20.167 × 10?7/Ω but the catalytic effect for oxidation reactions of linoleic and stearic acid decreased with an increasing B2O3. From these results, we can deduce that electrons shift from V4+ to V5+ with an increasing B2O3. FT-IR analysis showed an occurrence peak at 680 cm?1 and XPS analysis showed that a V4+ decrease and a V5+ increase are the basis of the electron shift from V4+ to V5+. We also verify the structure and change in properties from quantitative properties such as thermal properties, density, and molar volume.(Received May 16, 2014)