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In this research, a biomimetic, eagle-wing-type propeller was designed and applied to four pairs of counter-rotating propeller system to provide the necessary payload for a manned drone. The aerodynamic and noise characteristics were identified by model testing and compared with the numerical results using Ansys CFX 19.0 software. The structural analysis were also performed to reinforce the biomimetic blades by modifying the solid profiles near the hub. The aerodynamic performances of the counter-rotating propeller system were measured in terms of thrust forces by changing the distance between two counterrotating propellers and the pitch angle of the lower propeller. Based on the experiment, the best aerodynamic performance was identified at the pitch angle of 5° higher for the downstream propeller than that of upstream one and the non-dimensional distance of 0.3 between two counter-rotating propellers.

Objective To examine the effects of the gripping condition, device thickness, and hand length on bimanual perceived grip comfort associated with unrolling hand-held rollable screens. Background Rollable displays can be rolled and unrolled to change screen size. Although diverse rollable display device concepts have been suggested, little is known regarding ergonomic forms for comfortable screen unrolling. Method Thirty young individuals (10 in each hand-length group) evaluated three rollable display device prototypes in three gripping conditions (no restriction on using side bezels, minimal use of side bezels, and restriction on the gripping type). Prototypes differed in their right-side thickness (2, 6, and 10 mm). Side bezel regions grasped during screen unrolling and corresponding bimanual grip comfort ratings were obtained. Results To improve perceived grip comfort and accommodate user-preferred gripping methods, rollable display devices should be 6 mm (preferably 10 mm) thick (vs. 2 mm) and have at least 20-mm-wide side bezels. Relative to device thickness, gripping conditions were more influential on grip comfort ratings. The “no restriction” condition improved grip comfort ratings and strengthened bimanual coupling in terms of grip comfort ratings. Conclusion Contrary to current smartphone trends toward thinner and bezel-less designs, hand-held rollable display devices should be sufficiently thick and have sufficiently wide side bezels for screen unrolling. Application Hand-held rollable display devices should be 6- or preferably 10-mm thick (vs. 2 mm) and have at least 20-mm-wide side bezels to ensure higher perceived grip comfort during bilateral screen unrolling.

Limited information is available regarding ergonomic foldable display device forms. This two-stage study involving young South Koreans (divided into three hand-length groups) was conducted to determine ergonomic forms for hand-held foldable display devices considering folding/unfolding comfort and preference. Stage I obtained the suitability of three screen sizes for five tasks. Stage II evaluated 14 different bi- and tri-folding methods considering screen size, folding direction, and folding time. The effects of hand length were all non-significant. Screen size preferences were task-dependent; small screens were preferred for making calls, and medium screens for web searching and gaming. Folding methods affected folding/unfolding comfort and preference; outward screen and Z-shape screen folding were the most preferred bi- and tri-fold concepts, respectively. Screen protection and access appeared to be competing factors in the user preference determination process. Foldable screen size and folding method should be determined by considering tasks, folding/unfolding comfort, and user preferences.

This paper presents single-event upset (SEU) rates in flip-flops (FFs) in EUV 7 nm bulk-FinFET technology. EUV technology achieves high transistor-density, small FF cell-size, and low SEU rate. The alpha-SEU rate in EUV 7 nm FFs is 0.7X of the SEU rates in 10 nm FFs. The neutron-SEU rate in EUV 7 nm FFs is 0.6X of the SEU rates in 10 nm FFs. This paper also discusses the circuit dependence of the SEU rate in Normal-, Reset-, Set-FFs, and a soft-error immune FF (SEIFF), and SRAM.

This paper investigates soft error in memories and logic circuits in 28 nm planar-FDSOI technology by neutron, alpha, proton, and gamma-ray irradiation tests, and compares with SER in bulk-FinFET. The comparison elucidates the different SER trends between planar-FDSOI and bulk-FinFET.

This paper proposes an alternative method of alpha-irradiation test in flip-chip packages, backside irradiation test in EUV 7nm FinFET SRAM. The backside-test is conducted in backside-ground flip-chips. The sample thickness is measured, and the correlation factor is calculated by Monte-Carlo simulations. The results of backside- and front-side-tests show the dependability of the proposed method.

Objective: The authors aimed to identify ergonomic smartphone forms by investigating the effects of hand length, four major smartphone dimensions (height, width, thickness, and edge roundness), and smartphone mass on grip comfort and design attractiveness. Background: Despite their potential effect on grip comfort and design attractiveness, the dimensions specified above have never been simultaneously considered in a study investigating smartphone gripping. Method: Seventy-two young individuals participated in a three-stage study. Stage 1 determined the ranges of the four smartphone dimensions suitable for grip comfort and identified the strengths of their influences. Stage 2 investigated the effects of width and thickness (determined to have the greatest influence) on grip comfort and design attractiveness. Mock-ups of varying masses were fabricated using the dimensions determined during the first two stages to investigate the effect of mass on grip comfort and design attractiveness in Stage 3. Results: Phone width was found to significantly influence grip comfort and design attractiveness, and the dimensions of 140 × 65 (or 70) × 8 × 2.5 mm (height × width × thickness × edge roundness) provided high grip comfort and design attractiveness. The selected dimensions were fit with a mass of 122 g, with masses in the range of 106–137 g being comparable. Conclusion: The findings of this study contribute to ergonomic smartphone design developments by specifying dimensions and mass that provide high grip comfort and design attractiveness. Application: The dimensions and mass determined in this study should be considered for improving smartphone design grip comfort and attractiveness.

This paper presents the soft error rate (SER) in flip-flops of 10-nm FinFET technology, and discusses the scaling trend of SER from 14- to 10-nm FinFET technologies. Alpha and neutron irradiation test results show huge SER improvement in 10-nm FinFET technology. In a 10-nm FinFET, the alpha-induced SER decreases by $13.4\times $ , and the neutron-induced SER decreases by $3.1\times $ , compared to the 14-nm FinFET technology. The SER improvement is analyzed with the physics-based 3-D technology computer-aided design and Monte Carlo simulations. The simulation results show that fin-width scaling reduces the charge generation as well as charge collection which explains the SER improvement observed in 10-nm FinFET technology.

STT-MRAM has great attention as next generation memory to replace commercialized memory. However, not many articles are available on various MRAM reliability items. In this paper, we studied FBC trend of STT-MRAM with ECC off mode under various reliability stresses. We also show characterization of magnetic immunity for product design considerations. The STT-MRAM showed robustness against the FBC changes even after package level reliability stresses, magnetic stress and radiation stress. The negligible FBC changes with ECC off mode became to zero FBC with ECC on mode. This suggests that our intrinsic MRAM reliability is robust and also with design schemes like ECC, our STT-MRAM is ready for high volume production.

This paper proposes soft error immune flip-flop (SEIFF) for mitigating single event upset (SEU) in flip-flops (FFs) and impact of single event transient (SET) in combinational-logic. SEIFF mitigates the SET without enlarging setup-time and delay; there is no overhead in circuit performance. Alpha and proton tests validate the mitigation efficiency in SEIFF manufactured on 10 nm FinFET technology.