Machine Learning-Based Air-to-Ground Channel Model Selection Method for UAV Communications Using Digital Surface Model Data.

This paper proposes an automatic air-to-ground (A2G) channel model selection method based on machine learning (ML) using digital surface model (DSM) terrain data. In order to verify whether a communication network for a new non-terrestrial user service such as Urban Air Mobility (UAM) satisfies the required performance, it is necessary to perform a simulation reflecting the characteristics of the corresponding terrain environments as accurately as possible. For this simulation, A2G channel models corresponding to various terrain environments and a method of automatically classifying the terrain type of the simulation area must be provided. Many A2G channel models based on actual measurement results exist, but the practical automatic topography classification method still needs to be developed. This paper proposes the first practical automatic topography classification method using a two-step neural network-based classifier utilizing various geographic feature data as input. Since there is no open topography dataset to evaluate the accuracy of the proposed method, we built a new dataset for five topography classes that reflect the characteristics of Korea's topography, which is also a contribution of our study. The simulation results using the new data set show that the proposed ML-based method could increase the selection accuracy compared to the technique for direct classification by humans or the existing cross-correlation-based classification method. Since the proposed method utilizes the DSM data, open to the public, it can easily reflect the different terrain characteristics of each country. Therefore, the proposed method can be effectively used in the realistic performance evaluation of new non-terrestrial communication networks utilizing vast airspace such as UAM or 6G mobile communications.

Virucidal efficacy of acidic electrolyzed water (AEW) against African swine fever virus and avian influenza virus.

This study evaluated the virucidal efficacy of acidic electrolyzed water (AEW) against African swine fever virus (ASFV) and avian influenza virus (AIV), according to the Animal and Plant Quarantine Agency (APQA) guidelines for efficacy testing of veterinary disinfectants. AEW (pH 5.0-6.5) was prepared using a commercially available "Electrolyzed Water Generator" with a free chlorine concentration (FCC) of 5-140 ppm, and its efficiency in reducing the titer of ASFV and AIV was tested in a suspension under low- and high-level organic soiling. Under low-level organic soiling conditions, AEW with FCC ≥40 ppm was effective against ASFV; under high-level organic soiling conditions, AEW with FCC ≥80 ppm was effective against ASFV. Under low-level organic soiling conditions, AEW with FCC ≥60 ppm was effective against AIV; under high-level organic soiling conditions, AEW with FCC ≥100 ppm was effective against AIV. The virucidal effect of AEW seemed dependent on the FCC and the presence of organic soiling. Based on these data, we recommend the following minimum FCCs in AEW treatment for routine disinfection in veterinary field under low- and high-level organic soiling conditions: for ASFV, 50 ppm and 100 ppm; and for AIV, 75 ppm and 125 ppm, respectively. In conclusion, the virucidal effects of AEW against ASFV and AIV emphasize its potential utility as a disinfectant, and we suggest considering organic soiling conditions while using AEW for implementing effective control measures for field applications.

Thermal modeling and measurement of junctions in photovoltaic packages.

This study reports the direct thermal observation of the junction temperature and determination of the thermal resistance in a commercial solar cell package under actual operating conditions. A thermal transient method was the key method that was utilized for the thermal characterization of the device. Sunlight directed into the solar cell package was found to increase significantly the heat generation inside the solar cell package. It was shown that the operation of the solar cell package with sunlight of 1 sun resulted in a junction temperature of about 113 degrees C. The simulation data were in good agreement with the measured values. Detailed thermal performance of the solar cell package was projected using a Computational Fluid Dynamics (CFD) method under various operating conditions. Thermal resistance was determined under various operating conditions.

[Development of indicators to assess the stability of remnant blood samples stored in a biobank: experience at one institution].

BACKGROUND: One of the major concerns with biobanking is the absence of standard operating procedures to eliminate pre-analytical variation arising from sample collection, preparation, and storage. Currently, there is a lack of tools to carry out quality control procedures for stored blood samples. The aim of this study is to assess the quality of stored blood samples in our biobank and to suggest appropriate indicators for their quality control. METHODS: The stored blood samples that we tested have been registered into our biobank since 2003. These were transferred to our biobank after carrying out routine requested tests, because the samples would have otherwise been discarded. For the purpose of quality control, we analyzed the concentrations and the integrity of DNA and RNA extracted from the stored samples and tested the levels of several serum proteins; the results were compared with the corresponding pre-storage levels. RESULTS: A total of 19 samples were stored from 2006 to 2009. Of the 22 samples stored between 2003 and 2005, 50% showed complete DNA integrity. However, sufficient RNA integrity was noted in only 1 sample stored as recently as 2009. High blood urea nitrogen levels were also noted in the stored sera, but the increase did not correlate to the duration of storage. CONCLUSIONS: The amount and integrity of nucleic acids extracted from stored blood samples are potential indicators that can be used for quality control. A guideline for the quality assessment of stored blood samples in a biobank is urgently needed.