SiO<SUB>2</SUB> 젤화제를 첨가한 Jet A-1 젤 추진제의 특성 연구

김재우(Jaewoo Kim),전두성(Doosung Jun),문희장(Heejang Moon) 한국추진공학회 2011 한국추진공학회 학술대회논문집 Vol.2011 No.5

본 연구에서는 케로신 계열 액체 연료인 Jet A-1에 SiO2계열의 젤화제인 Aerosilⓡ R972, Silica 230, Silica 530을 첨가하여 젤 추진제를 제작하고 젤화 (gelification) 여부를 확인하기 위해 비 Newton 유체의 대표 모델인 power law model을 이용하였다. 본 연구에서 제작한 모든 젤 추진제는 전단박화 효과와 함께 젤화제의 함유량이 증가할수록 젤 추진제의 점도가 높게 형성됨을 확인하였다. Aerosilⓡ R972를 첨가한 젤 추진제는 전단률 증가와 함께 점도가 power law model을 따르며 감소하는데 반해 Silica230과 Silica 530을 첨가한 젤 추진제는 전단률 100 [1/g] 이전 구간에 대해 power law model에 벗어남을 확인하였다. This study investigates the rheological characteristics of SiO2-Kerosene gel propellants with Aerosilⓡ R972, Silica 230, Silica 530. Power-law rheological model is used to confirm whether or not gelification is achieved. It was found that the produced gel have shear-thinning effect, and that the viscosity of the gel propellants increases with increasing SiO2 concentration. Among gellants used in this study, gel propellant with Aerosilⓡ R972 fits most to the power law model as the shear rate increases. However, gels produced with Silica 230 and Silica 530 gellant deviate from the power law model when the shear rate regime is below 100 [1/g].

SiO₂ 계열 젤화제에 따른 케로신 젤 연료의 유변학적 특성 연구

김재우(Jaewoo Kim),전두성(Doosung Jun),강태곤(Teagon Kang),장석필(Seok pil Jang),구자예(Jaye Koo),문희장(Heejang Moon) 한국추진공학회 2012 한국추진공학회지 Vol.16 No.6

Present work deals three families of SiO₂ gelling agents which have been used to produce gel fuel based on Kerosene. Jet A-1 is chosen as fuel where power-law rheological model is used to confirm whether or not the gelification is achieved depending on the %wt of gellant. It was confirmed that the produced jelly-like substance have shear-thinning effect, and that its apparent viscosity increases as SiO₂ concentration increases. Compared to other gellants, gel with Aerosil® R972 fits most to the power-law model, while gels with Silica 230 and Silica 530 deviate from the power-law model. The rheological characteristics behaved differently depending on the mixing method(vortex mixing and manual mixing) when gellant concentration is increased.

Voltage-Tunable Multicolor, Sub-1.5 V, Flexible Electrochromic Devices Based on Ion Gels

Oh, Hwan,Seo, Dong Gyu,Yun, Tae Yong,Kim, Chan Young,Moon, Hong Chul American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.8

<P>Voltage-tunable multicolor electrochromic devices (ECDs) are fabricated based on flexible ion gels consisting of copolymers and ionic liquids as an electrolyte layer. Dimethyl ferrocene (dmFc) is incorporated into the gel, which serves as an anodic species. In this study, two electrochromic (EC) materials, monoheptyl viologen (MHr(+)) and diheptyl viologen (DHV2+), are employed and show significantly different EC behavior despite the similar chemical structure. Both MHr(+)- and DHV2+-containing ECDs are slightly yellowish in the bleached state, whereas the colored states are magenta and blue, respectively. All devices have good coloration efficiency of 87.5 cm(2)/C (magenta) and 91.3 cm(2)/C (blue). In addition, the required power of similar to 248 mu WW/cm(2) (magenta) and similar to 72,mu W/cm(2) (blue) to maintain the colored state put the ion gel-based ECDs in a class of ultralow power consumption displays. On the basis of the distinct difference in the coloration voltage range between MHV+ and DHV2+, and the rubbery character of the gel, flexible ECDs showing multiple colors are demonstrated. These results imply that voltage-tunable multicolor ECDs based on the gel are attractive to functional electrochemical displays.</P>

Output voltage modulation in triboelectric nanogenerator by printed ion gel capacitors

Lee, Ju Hyun,Park, Yun Sung,Cho, Sunghwan,Kang, In Seok,Kim, Jin Kon,Jeong, Unyong Elsevier 2018 Nano energy Vol.54 No.-

<P><B>Abstract</B></P> <P>The triboelectric nanogenerator (TENG) has been investigated intensively during the last decade in terms of power improvement and application as sensors, however, its voltage is usually too high and spike-like to be used directly as a power source for electronic devices. Although there was an effort to adjust the voltage through the circuit design, the complexity and the bulkiness of the circuit board make it difficult. Here, we propose a simple approach to change the spike-like voltage profiles to square-like profiles and adjust the output voltage to be suitable range for electronics. We used printed ion gel electrolyte patterns as capacitors and investigated the effects of dimension of the capacitor, connection types (serial, parallel) of multiple capacitors, and electrochemical conditions. The voltage profile of the TENG-ion gel system was modulated by the contact frequency applied to the TENG, the contact area of the ion gel with the electrode, the type of ions in the electrolyte, reduction/oxidation reaction in the gel, and the connection type (parallel, series) between ion gel patterns. We successfully demonstrated the light emission of a large number of printed electrochemiluminescence patterns.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Triboelectric voltage profile is modulated by printed ion gel electrolyte patterns. </LI> <LI> Dimension and connection type of the ion gel capacitors determine voltage profiles. </LI> <LI> Self-powered lighting of printed electrochemiluminescence patterns is demonstrated. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

인젝터 형상 변화에 따른 Gel 추진제의 유동 특성 연구

오정수(Jeongsu Oh),전두성(Doosung Jeon),최상태(Sangtae Choi),김덕윤(Deokyoon Kim),최양호(Yangho Choi),이정혁(Jeonghyuk Lee),문희장(Heejang Moon) 한국추진공학회 2010 한국추진공학회 학술대회논문집 Vol.2010 No.11

다양한 형상의 인젝터 내부 젤 추진제 유동을 수치적으로 연구하였다. 모사 젤 추진제의 유변학적 물성치를 측정하고 plain-orifice, chamfered-orifice 및 venturi 형상 인젝터의 유동 특성을 분석하였다. Plain-orifice 및 chamfered-orifice 인젝터의 경우 하류방향으로 유동이 진행할수록 점도가 높아지는 특성이 나타났으며 Venturi 형상의 경우 인젝터 내부 유동에서 낮은 점도가 지속적으로 유지됨을 알 수 있었다. Reynolds 수가 증가할수록 이러한 경향이 뚜렷하게 나타나는 것이 확인되었다. The present study investigates the flow characteristics of simulant gel propellant(carbopol 0.5%wt) in a variety of injectors. Rheological data for gel propellant has been measured and injector flow characteristics for plain-orifice, chamfered-orifice and venturi type injector have been numerically analyzed. The apparent viscosity of plain-orifice and chamfered-orifice have tendency to increase along axial direction, whereas for venturi type injector, low viscosity has been achieved in the injector flow. This phenomenon was clearly pronounced as Reynolds number is increased.

음극 Gel 조성에 따른 아연-공기 전지의 전기화학적 출력 및 용량 특성 연구

강민지(Minji Kang),정보영(Boyoung Jung),이병하(Byungha Lee),황갑진(Gabjin Hwang),유철휘(Cheolhwi Ryu) 한국전지학회 2023 한국전지학회지 Vol.3 No.1

저온공정 ZnO 적용에 따른 역구조 고분자 태양전지 소자 성능 연구

전재민(Jeon Jae-Min),신동열(Shin Dong-Yeol),정우진(Jeong Woo-Jin),곽희정(Kwak Hee-Jung),김준영(Kim Jun-Young) 한국태양에너지학회 2021 한국태양에너지학회 논문집 Vol.41 No.3

Recently, active research is being conducted on polymer solar cells to improve power conversion efficiency by developing new device structures, synthesizing polymer materials, and applying them to charge extraction layers. In this study, we analyzed the influence of ZnO on the performance of solar cells by using various ZnO thin films (using the high and low temperature sol-gel processes and the nanoparticle process) as an electron extraction layer in inverted polymer solar cells based on PBDB-T:ITIC. The ZnO thin film was formed by the high-temperature (450°C) sol-gel process, which resulted in an increase in the sheet resistance of the ITO electrode by five times. As a result, the power conversion efficiency of the polymer solar cells was low (4.12%). Conversely, in the nanoparticle process, butanol-based ZnO exhibited better dispersion and surface properties than the IPA-based ZnO, resulting in improved performance of the polymer solar cell (PCE of 6.35% and 4.58% with butanol and IPA-based ZnO, respectively). Additionally, a ZnO precursor solution was developed using the low-temperature (150°C) sol-gel process, which was applied as an electron extraction layer in an inverted polymer solar cell. Consequently, the device performance significantly improved (PCE of 8.89%)due to the formation of a ripple-shaped surface, which facilitated the extraction of electrons due to the excellent surface roughness.

Cavity Propagation Caused by Surface Discharge in Silicone Gel

Shin Nakamura,Masahiro Sato,Akiko Kumada,Kunihiko Hidaka,Sho Takano,Yuji Hayase,Keisuke Yamashiro,Tetsumi Takano 대한전기학회 2021 대한전기학회 학술대회 논문집 Vol.2021 No.10

Silicone gel is widely used to encapsulate power modules. The weakness of the insulation system is surface discharges propagating along with the interface between the silicone gel and substrate, which causes electrical degradation called a cavity. To realize more reliable power modules, there are high demands to clarify what mechanism the cavity propagates and what affects final cavity propagation length. This paper introduces our studies about the cavity phenomenon.

3-V Solid-State Flexible Supercapacitors with Ionic-Liquid-Based Polymer Gel Electrolyte for AC Line Filtering

Kang, Yu Jin,Yoo, Yongju,Kim, Woong American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.22

<P>State-of-the-art solid-state-flexible supercapacitors With sufficiently fast response speed for AC line filtering application suffer from limited energy density. One of the main causes of the low energy density is the low cell voltage (1 V), which is limited by aqueous-solution-based gel electrolytes. In this work, we demonstrate for the first, time a 3-V flexible supercapacitor for AC line filtering based on an ionic-liquid-based polymer gel electrolyte and carbon nanotube electrode material. The flexible supercapacitor exhibits an areal-energy density that is more than 20 times higher than that of the previously demonstrated 1-V flexible supercapacitor 0:66 vs 0.03 mu Wh/cm(2)) while maintaining excellent capacitive behavior at 120 Hz. The supercapacitor shows a maximum areal power density of 1.5 W/cm(2) and a time constant of 1 ins. The improvement of the cell voltage while maintaining the fast-response capability greatly improves the potential of supercapacitors for high-frequency applications in wearable and/or portable electronics.</P>

홍어껍질 추출물의 추출특성과 유지 산화억제 효과 및 콜라겐겔 제조

강건희(Kang, Keon-Hee),정갑섭(Jeong, Kap-Seop) 한국산학기술학회 2012 한국산학기술학회논문지 Vol.13 No.11

폐기되는 홍어껍질을 기능성 식품원으로 재이용하고자 홍어껍질 물 추출물의 추출특성과 세 종류의 식용유 에 대한 산화억제 효과를 측정하였으며, 추출 콜라겐의 겔화를 위한 최적조건 및 겔화제 선정, 겔의 저장성, 강도와 관능평가를 실시하였다. 50℃ 추출물의 방향족화합물 함량과 페놀성 화합물 함량은 25℃ 추출물에 비하여 각각 49.4%와 32.7% 높았으며, 50℃ 추출물의 환원력은 25℃ 추출물 보다 52.74% 높았으나 ascorbic acid의 14.9%, BHT의 27.8%였다. 추출물의 전자공여능은 방향족 화합물과 페놀성 화합물의 함량이 높을수록 높게 측정되었다. 식용유에 대 한 50℃ 추출물의 산화억제 효과는 옥수수 배아유, 대두유 및 올리브유 순이었으며, 식용유 종류에 따라 ascorbic acid 의 38.27~96.83%, BHT의 49.53~75.31%였다. 홍어껍질 추출물로부터 콜라겐 겔화의 최적 추출조건은 2.5배의 가수비 에서 100℃, 2시간이었으며, 조미하지 않은 경우에 비해 10% 조미한 경우 겔의 강도를 50%이상 저하시킬 수 있었고, 5개항에 걸친 관능평가 결과 상당한 개선을 보여 식품으로서의 제품화가 가능한 것으로 평가되었다. To enhance the reutilization of waste skate skin for the functional food resources, the investigations of extraction characteristics, antioxidative activity of skate skin water extracts on the oxidation of three cooking oils were carried out, and rheological properties, storage safety and sensory evaluation of collagen gel from skate skin were performed. Aromatic and phenolic compounds contents of 50℃ extracts were higher by 49.4% and 32.7%, respectively, than those of 25℃ extracts. Reducing power of extract at 50℃ was higher by 52.74% than that of 25℃ extract, but was 14.9% of ascorbic acid and 27.8% of BHT. Electron donating ability was corresponded to reducing power and phenolic compounds contents. Antioxidative effect of extracts on cooking oil was higher at 50℃ extract than 25℃ extract, and its order was on corn seed oil, soybean oil and olive oil. Antioxidative effect of 50℃ extract showed 38.27~96.83% and 49.53~75.31% of those of ascorbic acid and BHT, respectively, over three cooking oil. The optimum extraction condition for collagen gellation was 100℃, 2 hours extraction under 2.5 folds hydrolysis, and gel strength was lowered above 50% by 10% seasoning.