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도심환경에서의 전기자동차 친환경 자율주행 속도제어 전략
허슬기,정용환,이경수,Heo, Seulgi,Jeong, Yonghwan,Yi, Kyongsu 한국자동차안전학회 2018 자동차안전학회지 Vol.10 No.1
This paper proposes autonomous speed control strategy for an Electric Vehicle on urban road. SNU campus road is used to reperesent urban road situation. Motor efficiency of driving on campus circulation road can be improved by controlling velocity properly. Given information of campus road, especially slope of road, acceleration is selected from candidate, considering consumed power, human factor and driving time. To apply urban situation, preceding vehicle is also considered. With preceding vehicle, acceleration is defined according to clearance and relative velocity. Acceleration is bounded in normal range. Proposed acceleration control method is activated with proper velocity range for campus circulation road. With acceleration control, motor efficiency becomes better than driving with constant vehicle. To evaluate the performance of proposed acceleration controller, simulation study is conducted via MATLAB.
Lee, Su Jin,Lim, Yi Rang,Ji, Seulgi,Kim, Seong Ku,Yoon, Yeoheung,Song, Wooseok,Myung, Sung,Lim, Jongsun,An, Ki-Seok,Park, Jin-Seong,Lee, Sun Sook Elsevier 2018 Carbon Vol.126 No.-
<P><B>Abstract</B></P> <P>In order to realize the most suitable hybrid structure for air-stable graphene-based transparent and flexible electrodes, we systematically compared graphene oxide (GO)/Au/graphene and graphene/Au/GO hybrid films fabricated by layer-by-layer assembly. The sheet resistance of graphene/Au/GO was proportional to the concentration of AuCl<SUB>3</SUB> (1–5 mg/ml), which can be understood by a significant blue-shift in the G-band associated with the phonon stiffening. The size and density of formed Au nanoparticles strongly influenced their reduction reaction, which is a crucial factor for maximizing the doping effects. The optimized optical transmittance and sheet resistance of GO/Au/graphene were 94.9% and 198 ± 29 Ohm/sq, respectively. Furthermore, the hybrid films revealed stable doping effects (sheet resistance variation: 23–55%) against ambient conditions after 1 month. The variation in sheet resistance for GO/Au/graphene hybrid films corresponds to 30% with a bending radius of 10 mm after repeated bending tests (bending cycles of 10<SUP>5</SUP>).</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
전이학습을 활용한 군집제어용 강화학습의 효율 향상 방안에 관한 연구
이슬기,김권일,윤석민,Seulgi Yi,Kwon-Il Kim,Sukmin Yoon 한국군사과학기술학회 2023 한국군사과학기술학회지 Vol.26 No.4
Swarm has recently become a critical component of offensive and defensive systems. Multi-agent reinforcement learning(MARL) empowers swarm systems to handle a wide range of scenarios. However, the main challenge lies in MARL's scalability issue - as the number of agents increases, the performance of the learning decreases. In this study, transfer learning is applied to advanced MARL algorithm to resolve the scalability issue. Validation results show that the training efficiency has significantly improved, reducing computational time by 31 %.
김태우(Taewoo Kim),허슬기(Seulgi Heo),이경수(Kyongsu Yi),민경찬(Kyong Chan Min),신재곤(Jae Kon Shin) 대한기계학회 2018 大韓機械學會論文集A Vol.42 No.7
본 논문에서는 교통약자를 대상으로 하는 강건 자동비상제동 알고리즘을 개발하였다. 보행자와 자전거의 구분 없이 안전을 확보하기 위하여 등속 운동 모델을 사용하였으며, 자차량의 경우 일반 주행 상황과 운전자의 회피 거동을 모사하기 위하여 등가속도 모델을 사용하였다. 자동비상제동장치가 다양한 상황에서 안전 성능을 확보하도록 하기 위하여 측정 불확실성과 예측 불확실성을 고려하여 차량의 안전 영역을 설정하였다. 개발한 자동비상제동장치는 몇 가지 가정을 바탕으로 운전자가 사고를 회피하지 못한다고 판단될 경우 제동하도록 설계하였다. 개발한 강건 자동비상제동장치의 성능을 평가하기 위하여 차량시뮬레이션 프로그램인 Carsim과 MATLAB/Simulink를 이용하여 시뮬레이션을 수행하였다. 시뮬레이션 결과, 기존의 불변 안전거리 자동비상제동장치에 비해 제안한 알고리즘의 강건성을 확인하였다. This paper proposes a robust autonomous emergency braking (AEB) algorithm for vulnerable road users (VRU). Since it is difficult to distinguish between a pedestrian and cyclist, the behaviors of pedestrian and cyclist are described using a single constant velocity model. The motion of the host vehicle is then predicted using a constant acceleration model to describe the evasive as well as normal driving maneuvers of the driver. This predicted information is then used to judge the inevitability of a collision. To guarantee the robust safety performance of the AEB system, the measurement and prediction uncertainties are considered as safety boundaries. The proposed AEB algorithm is designed to be deployed if a collision is inevitable based on some assumptions. To evaluate the safety performance of the proposed AEB system, simulations are conducted with Carsim and MATLAB/Simulink. The robustness of the proposed algorithm compared with a deterministic AEB system is thus confirmed.
Kim, Seong Ku,Song, Wooseok,Ji, Seulgi,Lim, Yi Rang,Lee, Young Bum,Myung, Sung,Lim, Jongsun,An, Ki-Seok,Lee, Sun Sook Elsevier 2017 APPLIED SURFACE SCIENCE - Vol.425 No.-
<P><B>Abstract</B></P> <P>Recently, the importance of developing an effective catalyst for hydrogen evolution reaction is emphasized because hydrogen fueled energy conversion processes are gaining attention as the next generation energy production method. We propose a transition metal dichalcogenide composite catalyst based on molybdenum disulfide (MoS<SUB>2</SUB>) and tungsten disulfide (WS<SUB>2</SUB>) on reduced graphene oxide coated nickel (rGO-Ni) foams. The composite exhibited enhanced catalytic activity with observed on-set potential of ∼275mV at −10mA/cm<SUP>2</SUP> and Tafel slope of 54.1mV/dec when the composition of the composite was 50%MoS<SUB>2</SUB>-50%WS<SUB>2</SUB>. The composite catalyst demonstrated high-stability up to 300 cycles. In order to understand the enhanced catalytic activity, X-ray photoelectron spectroscopy compositional analysis was utilized. We propose that the enhancement of catalytic activities exhibited by the composited samples were achieved due to introduction of new type of interface between MoS<SUB>2</SUB> and WS<SUB>2</SUB> grains, regional transition of 2H phase MoS<SUB>2</SUB> and WS<SUB>2</SUB> to 1T phase, and formation of excess sulfur which depended directly on the composition.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A composite catalyst based on two 2D-dichalcogenides (MoS<SUB>2</SUB> and WS<SUB>2</SUB>) is proposed. </LI> <LI> The composite catalyst is synthesized based on solely on solution process. </LI> <LI> The composite catalyst exhibited 54.1mV/dec of Tafel slope. </LI> <LI> 1T-phase MoS<SUB>2</SUB> and WS<SUB>2</SUB> were found using XPS analysis. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Hong, Myunghee,Ye, Byong Duk,Yang, Suk-Kyun,Jung, Seulgi,Lee, Ho-Su,Kim, Byoung Mok,Lee, Soo Bin,Hong, Jeonghoon,Baek, Jiwon,Park, Sang Hyoung,Han, Buhm,Li, Yi,Liu, Wenting,Haritunians, Talin,Taylor, Oxford University Press 2018 JOURNAL OF CROHNS AND COLITIS Vol.12 No.6
<P>Conclusions: Our findings of new loci not previously associated with IBD support the importance of studying inflammatory bowel disease genetics in diverse populations.</P>