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Halide perovskite nanopillar photodetector
전도형,박종혁 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Enormous researches have been reported to introduce halide perovskite as a high-functional light-harvesting material. Composition and deposition approach have brought the impressive improvement; however, it has not shown a noticeable growth in performance of these materials these days. As a breakthrough, here a nanoimprinting crystallization technique is successfully demonstrated, which enables to fabricate the vertically-grown (VG) halide perovskites photodetectors. Ultimately, the 2-terminal lateral photodetectors based on the VG halide perovskite film shows far enhanced photocurrent, responsivity, and detectivity. We expect that the deposition method presented here help to surpass the technical limit and contribute to further improvement in various halide perovskite-based devices.
Tailored Porous Composite Separator via γ-ray Irradiation for Lithium Ion Battery
전도형,김진일,박종혁 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
Lithium ion battery (LIB) has taken a great part in modern industry and daily life because of its non-substitutable capability in energy storage system. However, safety problems such as explosion are occasionally reported, ensuing from thermally vulnerable property of commercial PE separator. So, safety issue about thermal stability is a problem awaiting solution to be solved, satisfying electrochemical characteristics and stability as well. In this work, tailored composite separator with uniform morphology is introduced to replace precarious PE separator, arising from nano-scale graphene oxide for controlling pore structure and distribution in polymeric coating layer via γ-ray irradiation technique. Uniform ion flux by regular pore morphology induces stable cell characteristics with various current density and long cycles. Moreover, its controlled morphology is not devastated and shrunk in harsh environment at 150°C condition, showing excellent thermal stability.
전도형,박종혁 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
Metal lead halide perovskites have been focused as a promising next generation photoelectronic materials. Compositional and deposition approaches have contributed to boosting the photoconversion efficiency and its stability against air and moisture. Although its unprecendented performance breakthrough, metal halide halide perovskites suffer from stagnation in terms of photoconversion efficiency. As a strategic modification, we introduced pressure-induced crystallization method, which can tailor not only nanostructure but also intrinsic properties of metal lead halide perovskites itself resulting in performance efficiency. By exerting pressure with simple and easy-tofollow technique, we developed high-performance photodetectors utilizing nanopillar-structured metal lead halide perovskites, which exhibited enhanced photoresponsivity. Additionally, we succesfully fabricated nanodot-arrayed metal lead halide perovskite films, which shows enhanced film stability against moisture.
전도형(Do-Hyung Jeon),최주형(Joo-Hyung Choi),조진래(Jin-Rae Cho),김기전(Gi-Jeon Kim),우종식(Jong-Shik Woo) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
This study is concerned with the braking distance estimation using frictional energy rate. First, steady state rolling analysis is performed, and using this result, the braking distance is estimated. Dynamic rolling analysis during entire braking time period is impratical, so that this study divides the vehicle velocity by 10㎞/h to reduce the analysis time. The multiplication of the slip rate and the shear stress provides the frictional energy rate. Using frictional energy rate, total braking distance is estimated. In addition. ABS(Anti-lock Brake System) is considered, and two type of slip ratios are compared. One is 15% slip ratio for the ABS condition. and the other is 100% slip ratio which leads to the almost same braking distance as the elementary kinematic theory. A slip ratio is controlled by angular velocity in ABAQUS/Explicit. A 15% slip ratio gives the real vehicle's braking distance when the frictional energy occurred at disk pad is included. Disk pad's frictional energy rate is calculated by the theoretical approach,
유한요소법을 이용한 구동상태에 따른 타이어의 특성 분석
전도형(Do-Hyung Jeon),최주형(Joo-Hyung Choi),조진래(Jin-Rae Cho),김기운(Kee-Woon Kim) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
This paper discusses the measurement of tire driving performance for 2 types of tire model. Tire is almost composed of rubber, and this is related with the bearing capacity of tire due to the external force. In this study, an explicit time integration method has been used to simulate steady state rolling along a straight path and over a cleat. And analysis for tire dynamic response rolling over a cleat is importnat to study automobile NVH properties. Besides, the evaluation of contact shear force is perfomed for steady state rolling and braking state. The results show that there are noticeable differences between 205/60R15 and 225/60R15 tire model.
이정환,전도형,박종혁 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Although its high photoconversion efficiency (PCE), low humidity stability blocks the way toward commercialization of halide perovskite-based photovoltaics. To overcome this critical hurdle, it is important to focus on grain boundary of halide perovskites. Accordingly, engineering grain boundary of halide perovskites can be a promising way to fabricate devices with high humidity stability. Herein, pressure-induced crystallization of halide perovskite film is demonstrated as a grain boundary healing technique for high moisture stability. After exposure to the condition of RH 85% 30 °C, we observed enhanced moisture stability. Also, we revealed that pressure-induced crystallization enhances moisture stability not only by enlarging grain size of halide perovskites but also by reducing grain boundary angles. The devices with pressure-induced crystallization exhibited dramatically stabilized performance, sustaining over 0.7 normalized PCE after 200hr under RH 45%, 30°C.