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Uplink time synchronization techniques for Non-terrestrial Network (NTN) in 3GPP Release 17 are introduced. Uplink time synchronization is important for NTN because the uplink waveform is based on OFDM (thus requiring the transmission from all users to arrive within the cyclic prefix), and it is challenging in the case of LEO and MEO, because the propagation delay changes orders-of-magnitude faster than that in a typical terrestrial network. The uplink time synchronization follows a dual-loop approach: an open loop that calculates the service link delay based on the UE location and the satellite location and the feeder link delay based on parameters received from the network, and a closed loop that accumulates timing advance (TA) commands, intended to correct any residual timing error from the open loop. We examine the double correction issue resulting from the interaction between the two control loops and explain the 3GPP specification that addresses the issue. We also explain how to calculate the timing advance with examples.

Fog screens offer a great advantage to be used as scattering screens in three‐dimensional displays. In the absence of a fixed rigid form, fog screens work as screens without any physical obstruction. The density of water droplets can be regulated to adjust the screen's transparency and scattering level. This study proposes a method for crosstalk reduction between adjacent viewing windows by decreasing the divergence of view of the projector, with concentration lenses. By applying the Scheimpflug principle, we also reduce the keystone effect, which occurs when the fog screen is slanted with respect to the optical axis. In this study, we have realized a tabletop multiview fog display without any structures on the table and established that the proposed method is feasible for decreasing crosstalk effectively.

In the present study, a methodology for conducting a system-level analysis of a fan–motor assembly in a vacuum cleaner is presented. This system consisted of three components, a fan, motor, and the flow resistance of the motor, or of the vacuum cleaner. The combined characteristics of the fan and the motor were obtained from torque matching at a constant throttling condition, and a pressure drop was implemented under a constant flow rate to account for the flow resistance. By combining these two steps, the performance characteristics of the fan–motor assembly and the vacuum cleaner system could be predicted over the whole range of operation, based on the characteristics of each component. The predicted performance for power, flow rate, pressure, and efficiency using the present method agreed well with the experimental results obtained for an equivalent system, within 2% difference at best efficiency point. Three models of the fan–motor assembly (S1, S2, and S3) were analyzed at the component level, and the decrease in efficiency produced by flow resistance was estimated to be 1% (S1 and S3 models) or 4.7% (S2 model) using the present method. The characteristics of the fan, extracted from those of the fan–motor assembly, were used for validating the computational fluid dynamics. The computational fluid dynamics results of this study predicted higher efficiency due to simplification of the geometry, but an accurate prediction of best efficiency point location was obtained. The proposed method is also applicable for detecting system leakage and identifying system resistance without direct measurement.

The determination of the shape and rising velocity of gas bubbles in a liquid pool is of great importance in analyzing the radioactive aerosol emissions from nuclear power plant accidents in terms of the fission product release rate and the pool scrubbing efficiency of radioactive aerosols. This article suggests a simple parameterization for the gas bubble rising velocity as a function of the volume-equivalent bubble diameter; this parameterization does not require prior knowledge of bubble shape. This is more convenient than previously suggested parameterizations because it is given as a single explicit formula. It is also shown that a bubble shape diagram, which is very similar to the Grace's diagram, can be easily generated using the parameterization suggested in this article. Furthermore, the boundaries among the three bubble shape regimes in the Eo–Replane and the condition for the bypass of the spheroidal regime can be delineated directly from the parameterization formula. Therefore, the parameterization suggested in this article appears to be useful not only in easily determining the bubble rising velocity (e.g., in postulated severe accident analysis codes) but also in understanding the trend of bubble shape change due to bubble growth.

This study examines the impact of extended tourist trust constructs on domestic travel experiences, subjective well-being, and future travel intention in the pandemic. Data was obtained through a survey conducted on 1181 Korean and American domestic tourists. The results show that policy trust and destination trust have positive effects on travel frequency and satisfaction. Moreover, interactional trust positively impacted travel satisfaction. While both travel frequency and travel satisfaction have positive impacts on subjective well-being of travelers, travel satisfaction has a stronger impact on subjective well-being than travel frequency. However, certain relationships were influenced by national backgrounds (U·S vs. Korea).

Mesencephalic precursors derived from early embryonic day 12 E12 rat embryos were grown in vitrousing mitogen basic fibroblast growth factor bFGF and these cells efficiently differentiated into dopaminergic DA neurons. However, this in vitroDA differentiation was poor in mesencephalic precursors isolated from later embryos E13–15. Ascorbate AA treatment enhanced yields of DA neurons from E12 precursors, and increased the number of DA neurons generated from E13 precursors to levels attained when using E12 precursors. AA markedly upregulated expression of bone morphogenetic protein 7 BMP7 and erythropoietin Epo in precursors, but did not affect expression of a number of genes known to regulate midbrain DA development. The addition of these recombinant proteins or blockers revealed that both BMP7 and Epo mediate AAinduced DA neuron differentiation.