Thin film solid oxide fuel cells (TF-SOFCs) are considered to be a promising next generation energy conversion device. TFSOFCs have many advantages such as rapid turn-on and off, fuel flexibility, material flexibility, high power density and availability of compact system. Electrodes and electrolytes of TF-SOFCs are fabricated by thin film processes. In order to fabricate high performance TF-SOFCs, proper thin film processes have to be used due to the unique requirements of each part of the TF-SOFCs. This paper reviews the thin film deposition process for fabrication of TF-SOFCs and the advantages and disadvantages of physical and chemical vapor deposition processes. In addition, materials prepared through thin film processes and the performance results of TF-SOFCs are reviewed.
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Manipulating the grain boundary properties of BaCeO3-based ceramic materials through sintering additives introduction Gennady Vdovin, Anna Rudenko, Boris Antonov, Vacheslav Malkov, Anatoly Demin, Dmitry Medvedev Chimica Techno Acta.2019; 6(2): 38. CrossRef
High-k dielectric thin films are widely applied in energy conversion/storage and information storage devices such as Dynamic Random access Memory (DRAM), Multilayer Ceramic Capacitor (MLCC), thermoelectric devices, etc. Among them, perovskite thin films, for instance, strontium titanate (STO) and barium titanate (BTO) are known to have extremely superior dielectric properties. Atomic layer deposition (ALD), can deposit thin films through atomic layering producing uniform and conformal high-k thin films with precise thickness control. While relatively low crystallinity of film quality due to low deposition temperatures of ALD can develop practical issues, they can be overcome by employing additional processes such as thermal annealing, plasma treatment, and seed layering. ALD, STO and BTO thin films treated with these additional processes demonstrate more improved crystallinity and electrical properties. In this paper, the processes to enhance properties of ALD high-k thin films, BTO and STO films are reviewed. Perspectives into high quality ALD high-k thin films as well as current efforts to further improve the film quality are discussed.
The objective of this study was to investigate the effect of heat treatment on electrochemical performance of aluminum (Al)-air battery. We prepared a pure Al and an annealed Al under an annealing environment [a mixture gas of Ar (97%) and H2 (3%)] of 400°C for 1 hr. Based on electron backscatter diffraction analysis of Al at the anode, the relative misorientation of the pristine Al was higher than that of the annealed Al. Electrochemical performances of the pristine Al-air and the annealed Al-air were also compared. The annealed Al-air battery showed slightly higher power density than the pristine Alair battery. These results suggest that annealing with heat treatment is an important process to improve the electrochemical performance of aluminum-air battery.
Solid oxide fuel cells (SOFCs) are at a technological level close to commercialization, which could be enabled by new material research. Especially, not only an electrolyte, but also a cathode material becomes very important to further increase electrochemical performance, due to the effort to lower operating temperature of SOFCs to intermediate range (400-600℃) to take advantage of high and low temperature operation. Unfortunately, this trend inevitably results in demand for new cathode materials with high oxygen reduction reaction activity, as well as high mechanical durability. Recently, ceramic materials which conduct oxygen ion, proton, and electron, thereby called ‘triple conducting oxide’ are being highlighted, due to their excellent material properties, to be used for cathodes of SOFCs. This paper reviews the three representative triple-conducting oxides, which were already used and tested in SOFC operating conditions.
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Recent advances in layered Ln2NiO4+δnickelates: fundamentals and prospects of their applications in protonic ceramic fuel and electrolysis cells Artem P. Tarutin, Julia G. Lyagaeva, Dmitry A. Medvedev, Lei Bi, Aleksey A. Yaremchenko Journal of Materials Chemistry A.2021; 9(1): 154. CrossRef
This paper presents a search methodology for the optimal operational path of robots using a genetic algorithm. The work scheduled to be performed using a robot was characterized. Collision avoidance between the robot including the working tool and the target object was considered. In this study, we followed the general steps of data mining. We compared the time taken by the robot moving along the path created by our proposed methodology with the time taken for the robot along the path created by real humans. The results show that the path generated by this study was more efficient than that of humans.
This study is to investigate convection cooling performance of the Secondary Battery of Electric Vehicle without heat sink. Research is focused on the comparative study on cooling between forced convection and natural convection cooling. Selected local locations for various temperature distributions had shown in the flow domain. Final temperature on the cell surface has been compared by forced convection with natural convection. According to the results of velocity and temperature distributions in the fluid domain, Buoyancy appear by density difference in the natural convection. Apparent vortex was detected in the fluid domain for forced convection. According to calculations of convective heat transfer coefficient between cell and atmosphere in the battery pack, average value of more 70-78% heat transfer coefficient increased by forced convection than natural convection. Average temperature value of the cell surface decreased up to 46.50% by forced convection. Due to vortex by air, cooling performance of forced convection is excellent. In addition, cooling on edge of the battery is better than heat source location.
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A Study on Heat Radiation Performance for Different Layout of Electric Vehicle Secondary Battery Cell Seung Bong Hyun, Byeong Yeop Kim, Ji Hun Song, Dong-Ryul Lee Journal of the Korean Society for Precision Engineering.2020; 37(4): 271. CrossRef
Silicon nitride/cobalt tungsten boride (SiN/CoWB) passivation layer improves mass transport rate at copper thin film layers of semiconductor wafers after chemical mechanical polishing process. This study evaluates mass transport at the interface between copper and passivation layers by stress relaxation method, followed by deduction of interface diffusivity via a kinetic model. For comparison, SiN/CoWB, SiN, silicon carbon nitride (SiCN) and silicon carbide (SiC) passivation layers are introduced. A thin layer of SiN/CoWB demonstrates an outstanding performance as diffusion retarding material, especially at high temperature. The order of stress relaxation in terms of passivation layers is SiN/CoWB < SiN < SiCN < SiC, implying the order of mass transport at the interface. Using the kinetic model, the diffusivities and activation energies regarding passivation layers are calculated and reveal a good agreement with experimental results.
The CSU (continuous ship uploader) is one of the most advanced and high-tech machines among the logistics facilities. It is giant heavy equipment and has a number of driving systems compared to a general crane. In general, CSU is designed to have a life of 20 years, but recently it has been increased up to 30-50 years or is being used as a semi-permanent facility. In this study, based on the structural analysis and the elasto-plastic fracture mechanics, fracture toughness test was performed on the front tension bar, which is the main load bar of the CSU machine. The J-integral analysis was performed on the front tension bar. Based on the results of the J-integral analysis and fracture resistance test, the critical crack length without instantaneous fracture was calculated and analyzed for each operating load.
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Prediction of the Remaining Useful Life of L-holder for Continuous Ship Unloader Seung-Hun Lee, Dong-Woo Lee, Jung-Il Song Journal of the Korean Society for Precision Engineering.2023; 40(8): 647. CrossRef
The vibration analysis of flexible rotor systems supported by angular contact ball bearings is presented. Vibration analysis of rotor-ball bearing systems has often been performed via simplification of supporting bearings as linear springs with constant stiffness. In this study, an improved model of rotor-ball bearing systems was proposed. It utilizes a general bearing model based on response and time-dependent bearing characteristics. The system equations of motion were established using the finite-element method and numerically solved using the Newmark-β method. The method was used to recalculate the bearing stiffness matrices at every interval of numerical integration as a function of the instantaneous bearing displacements using a separated five-degrees-of-freedom bearing model. The method was verified via comparison with experimental data available in the literature. The extended simulations were conducted to investigate the unbalanced responses of a rotor-ball bearing system using the proposed and conventional methods. Numerical results showed a meaningful discrepancy between the vibrational responses obtained by the proposed model using the response and timedependent bearing stiffness model and the traditional constant-stiffness model.
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Study on Thermo-mechanical Modeling and Analysis of High-speed Angular Contact Ball Bearings Under Oil-jet Lubrication Gilbert Rivera, Shinhyang Park, Chan-sik Kang, Dongjoo Kim, Seong-Wook Hong Journal of the Korean Society for Precision Engineering.2024; 41(7): 569. CrossRef
This study investigated the role of multi-layer lever type flexure hinges for high magnification of piezoelectric actuators and their optimal design. In order to obtain a displacement higher than 700 μm with a common PZT actuator of displacement less than 15 μm, the magnification ratio of a flexure hinge must be at least 50 or higher. Under a limited compact space, a multi-layer lever structure represents a useful alternative. Restricting the important design parameters to the number of layers and rotational stiffness of notch, the maximum required input displacement/force and the maximum output displacement were analyzed according to the number of layers. The two-layer structure was selected as the best option for large magnification ratio because the required input displacement was drastically reduced. FEM analysis revealed that the lever thickness should be larger than 12 mm to exhibit a rigid body behavior. The output displacement was 664 μm, which was less than 704 μm expected in the design stage. It might be attributed to elastic deformation of the notches of 1st and 2nd layers, which was not considered in the design stage.
Previous studies on joint angle estimation have been restricted to slow-speed level walking conditions, even though slope walking and running elicit unique biomechanical characteristics. Measurements were mostly based on an optical motion capture system despite in-the-lab limitation of measurement technique. The contribution of this study is twofold: (i) to propose a joint angle estimation method by applying a state-of-the-art parallel Kalman filter based on an inertial measurement unit (IMU) that can overcome in-the-lab limitation, and (ii) to demonstrate its application to level walking condition as well as slope walking and running conditions to fill a gap in joint kinematics literature. In particular, this study focuses on knee flexion/extension and ankle dorsiflexion/plantarflexion angles at various speed variations. The parallel Kalman filter applied in the proposed method can compensate external acceleration through Markov-chain-based acceleration modeling, that may enhance joint estimation performance in high speed walking conditions. To validate the proposed estimation method, an optical motion capture system was used as reference. In addition, patterns for each condition were investigated to identify and evaluate presence of classifying features.
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Evaluating Sparse Inertial Measurement Unit Configurations for Inferring Treadmill Running Motion Mackenzie N. Pitts, Megan R. Ebers, Cristine E. Agresta, Katherine M. Steele Sensors.2025; 25(7): 2105. CrossRef
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Comparison of Concurrent and Asynchronous Running Kinematics and Kinetics From Marker-Based and Markerless Motion Capture Under Varying Clothing Conditions Robert M. Kanko, Jereme B. Outerleys, Elise K. Laende, W. Scott Selbie, Kevin J. Deluzio Journal of Applied Biomechanics.2024; 40(2): 129. CrossRef
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Validity and repeatability of a new inertial measurement unit system for gait analysis on kinematic parameters: Comparison with an optoelectronic system Elodie Piche, Marine Guilbot, Frédéric Chorin, Olivier Guerin, Raphaël Zory, Pauline Gerus Measurement.2022; 198: 111442. CrossRef
Application of Artificial Neural Network for Compensation of Soft Tissue Artifacts in Inertial Sensor-Based Relative Position Estimation Ji Seok Choi, Jung Keun Lee Journal of the Korean Society for Precision Engineering.2022; 39(3): 233. CrossRef
Recreating the Motion Trajectory of a System of Articulated Rigid Bodies on the Basis of Incomplete Measurement Information and Unsupervised Learning Bartłomiej Nalepa, Magdalena Pawlyta, Mateusz Janiak, Agnieszka Szczęsna, Aleksander Gwiazda, Konrad Wojciechowski Sensors.2022; 22(6): 2198. CrossRef
Development of a Low-Cost Open-Source Measurement System for Joint Angle Estimation Túlio Fernandes de Almeida, Edgard Morya, Abner Cardoso Rodrigues, André Felipe Oliveira de Azevedo Dantas Sensors.2021; 21(19): 6477. CrossRef
Drift Reduction in IMU-based Joint Angle Estimation for Dynamic Motion-Involved Sports Applications Jung Keun Lee, Chang June Lee Journal of the Korean Society for Precision Engineering.2020; 37(7): 539. CrossRef
Relative Position Estimation using Kalman Filter Based on Inertial Sensor Signals Considering Soft Tissue Artifacts of Human Body Segments Chang June Lee, Jung Keun Lee JOURNAL OF SENSOR SCIENCE AND TECHNOLOGY.2020; 29(4): 237. CrossRef
Kinematic Constraint-Projected Kalman Filter to Minimize Yaw Estimation Errors Induced by Magnetic Distortions Tae Hyeong Jeon, Jung Keun Lee Journal of the Korean Society for Precision Engineering.2019; 36(7): 659. CrossRef
[Purpose] To investigate the correlation between joint position sense (JPS) during hip abduction and static/dynamic balance abilities. [Method] The study enrolled 22 healthy college undergraduates and a smartphone application known as Clinometer was used to measure JPS during hip abduction using the passive setting/active reproduction. Balance ability was measured at levels 12, 7, and 3 of the Biodex Balance System. The JPS error during hip abduction was correlated with balance ability in relation to sway level. [Results] Error in JPS during hip abduction was moderately correlated with all balance scores at all sway levels (r≥0.38, p≤0.04 for all), except for the anterior-posterior balance at levels 12 and 3 (r≤0.24, p≥0.30 for both). [Conclusion] A significant correlation existed between JPS during hip abduction and balance ability, regardless of sway level. Therefore, adequate sensory training of the hip joint is needed during balance training.
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