ScholarWorks@KumohThe ScholarWorks digital repository system captures, stores, indexes, preserves, and distributes digital research material.http://scholarworks.bwise.kr:80/kumoh2024-03-19T22:16:36Z2024-03-19T22:16:36ZToward feasible single atom-based hydrogen evolution electrocatalysts via artificial ensemble sites for anion exchange membrane water electrolyzerLim, Won-GwangTruong, Hoang NamJeong, Jae-YeopKim, DongkyuOh, Lee SeulJo, ChangshinKim, ChihoKim, Hyung JuChoi, Sung MookShin, HyeyoungLee, SeonggyuLim, Eunhohttps://scholarworks.bwise.kr/kumoh/handle/2020.sw.kumoh/264482024-02-28T04:30:38Z2024-04-01T00:00:00ZTitle: Toward feasible single atom-based hydrogen evolution electrocatalysts via artificial ensemble sites for anion exchange membrane water electrolyzer
Authors: Lim, Won-Gwang; Truong, Hoang Nam; Jeong, Jae-Yeop; Kim, Dongkyu; Oh, Lee Seul; Jo, Changshin; Kim, Chiho; Kim, Hyung Ju; Choi, Sung Mook; Shin, Hyeyoung; Lee, Seonggyu; Lim, Eunho
Abstract: Approaching an efficient anion exchange membrane water electrolyzer (AEMWE) with satisfactorily high ki-netics in the alkaline hydrogen evolution reaction (HER) is desired. We design an advanced platinum (Pt) single atom (SA)-based electrocatalyst by incorporating the Ni nanoparticle as an artificial ensemble site adjacent to Pt SA. The designed Pt SA electrocatalyst achieves higher areal current density (500 mA cm-2 at 1.8 V) in the single cell of the AEMWE and better cell voltage stability than the Pt/C electrocatalyst. The Ni nanoparticle assists in separating the binding sites of H* and OH*, in which Ni atoms provide adsorption sites for H*, while OH* adsorbs on the Pt SA. This separation effect drastically accelerates the energy barrier required for the water dissociation reaction in the Volmer step and simultaneously optimizes the H* and OH* binding energy, which extremely enhances the alkaline HER kinetics, thereby demonstrating the feasibility of Pt SA electrocatalysts for AEMWE.2024-04-01T00:00:00Z진공 브레이징을 통해 제조한 TiAl/HI-TEMP 820/SCM440H 재료의공정 온도에 따른 미세조직 및 기계적 특성 평가유상규김지원이초롱오명훈최인철https://scholarworks.bwise.kr/kumoh/handle/2020.sw.kumoh/285102024-03-13T01:30:28Z2024-03-01T00:00:00ZTitle: 진공 브레이징을 통해 제조한 TiAl/HI-TEMP 820/SCM440H 재료의공정 온도에 따른 미세조직 및 기계적 특성 평가
Authors: 유상규; 김지원; 이초롱; 오명훈; 최인철
Abstract: The TiAl alloy is attracting attention as a lightweight and heat-resistant material, because of itshigh specific strength, excellent high-temperature formability, and fatigue strength. However, its applicationsare limited by its high unit price and low room temperature ductility. To overcome this issue, dissimilarlybonded materials have been extensively employed. This involves joining a brittle metal to a low-cost metalthat possesses excellent plasticity, using various dissimilar bonding techniques. In this study, TiAl/HI-TEMP820/SCM440H materials were fabricated using a vacuum brazing process under different temperatureconditions. After the brazing process, the microstructure of the interfacial area revealed seven distinct layersresulting from chemical reactions between the base metals and the filler metal. These reaction layersconsisted of a Ni solid solution, intermetallic compounds (Ti3Al, TiNi2Al, Ti2Ni, FeNi), and borides (CrB, TiB2,FeB). To analyze the effect of brazing temperature on the relationship between the microstructure andmechanical properties at the interface of TiAl/HI-TEMP 820/SCM440H materials, conventional uniaxial testsand nanoindentation tests were performed. The measured nanohardness exhibited a significantly largedistribution for each reaction layer, with the highest hardness values observed in the intermetallic compoundsand borides layers. Additionally, room temperature tensile tests confirmed that fractures initiated in the highhardnessand brittle intermetallic compounds and borides layers.2024-03-01T00:00:00ZHead-Up Haptic Display Using Dual-Mode Haptic Actuator for VehiclesHeo, Yong HaeKim, Tae-HoonChoi, Dong-SooKim, Sang-Younhttps://scholarworks.bwise.kr/kumoh/handle/2020.sw.kumoh/285022024-03-13T01:30:25Z2024-03-01T00:00:00ZTitle: Head-Up Haptic Display Using Dual-Mode Haptic Actuator for Vehicles
Authors: Heo, Yong Hae; Kim, Tae-Hoon; Choi, Dong-Soo; Kim, Sang-Youn
Abstract: Driving assistance modules are important components to improving driver safety in driving environments, which can create overloaded multisensory information. This article introduces the concept of a head-up haptic display that assists drivers in keeping their visual attention focused, and then offers a haptic actuator that may be used as the main component in the head-up haptic display. We selected magneto-rheological elastomer (MRE) as the base material and adopted a porous structure to reduce its initial stiffness. Furthermore, we fabricate a haptic actuator based on an MRE having a porous structure (pMRE) and a solenoid. The current to the solenoid generates a magnetic field that causes the pMRE to stiffen, thereby increasing the resistive force. As soon as the current input is removed, the pMRE becomes soft again. We simulated the solenoid coil and the magnetic path to further maximize the magneto-motive force generated by the solenoid coil and experimentally optimized the pMRE. We showed that the proposed haptic actuator creates not only a sufficient resistive force but also vibration to generate various haptic sensations. Moreover, we constructed a head-up haptic display using four haptic actuators and demonstrated the possibility of utilizing a new user interface to increase driving safety.2024-03-01T00:00:00ZUtilizing machine learning for reactive material selection and width design in permeable reactive barrier (PRB)Ren, YangminCui, MingcanZhou, YongyueSun, ShiyuGuo, FengshiMa, JunjunHan, ZhengchangPark, JooyoungSon, YounggyuKhim, Jeehyeonghttps://scholarworks.bwise.kr/kumoh/handle/2020.sw.kumoh/284972024-03-13T01:30:23Z2024-03-01T00:00:00ZTitle: Utilizing machine learning for reactive material selection and width design in permeable reactive barrier (PRB)
Authors: Ren, Yangmin; Cui, Mingcan; Zhou, Yongyue; Sun, Shiyu; Guo, Fengshi; Ma, Junjun; Han, Zhengchang; Park, Jooyoung; Son, Younggyu; Khim, Jeehyeong
Abstract: Permeable reactive barrier (PRB) is an important groundwater treatment technology. However, selecting the optimal reactive material and estimating the width remain critical and challenging problems in PRB design. Machine learning (ML) has advantages in predicting evolution and tracing contaminants in temporal and spatial distribution. In this study, ML was developed to design PRB, and its feasibility was validated through experiments and a case study. ML algorithm showed a good prediction about the Freundlich equilibrium parameter (R2 0.94 for KF, R2 0.96 for n). After SHapley Additive exPlanation (SHAP) analysis, redefining the range of the significant impact factors (initial concentration and pH) can further improve the prediction accuracy (R2 0.99 for KF, R2 0.99 for n). To mitigate model bias and ensure comprehensiveness, evaluation index with expert opinions was used to determine the optimal material from candidate materials. Meanwhile, the ML algorithm was also applied to predict the width of the mass transport zone in the adsorption column. This procedure showed excellent accuracy with R2 and root -mean -square -error (RMSE) of 0.98 and 1.2, respectively. Compared with the traditional width design methodology, ML can enhance design efficiency and save experiment time. The novel approach is based on traditional design principles, and the limitations and challenges are highlighted. After further expanding the data set and optimizing the algorithm, the accuracy of ML can make up for the existing limitations and obtain wider applications.2024-03-01T00:00:00Z