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Abstract This study aimed to establish the optimal production conditions for mealworm chitosan oligosaccharides (MCOS) using the response surface methodology and measure the prebiotic effect of MCOS prepared on cecal microbiota through in vitro anaerobic fermentation. The optimal conditions for MCOS production using chitosanase were 2.5% substrate, 30 mg/g enzyme, and 6 h reaction time. Matrix-assisted laser desorption ionization-time of flight mass spectrometry, Fourier transform infrared spectroscopy, and in vitro assays to confirm that the chemical structure and physicochemical properties of MCOS are similar to those of commercially available chitosan oligosaccharides. The growth of Lactobacillus acidophilus, Lacticaseibacillus casei, and Bifidobacterium bifidum was increased by MOCS and confirmed that the prebiotic effect of MCOS was significant in a concentration-dependent manner. The addition of 1% and 2% MCOS to in vitro anaerobic fermentation resulted in changes in the content of short-chain fatty acids (SCFAs) and an increase in Verrucomicrobiota abundance compared with the control. In the case of Romboutsia, Turicibacter, and Akkermansia, a significant increase was confirmed in the MCOS-containing groups compared to that in the control group. Compared to 2% MCOS, 1% MCOS more significantly affected Lactobacillus levels. MCOS produced by chitosanase under optimal conditions contains oligosaccharides with 2–6 degree of polymerization and exerts a prebiotic effect that affects changes in the SCFA content and microbiota composition in the cecum.

This paper presents a large-scale base station antenna assembly structure that is low-cost, reliable, and easy to manufacture. The antenna element is composed of a low-loss liquid crystal polymer based on a plastic molded module and a modified wideband stacked patch antenna. The base station antenna consists of a 4 × 8 antenna module, with each module comprising 3 × 1 subarrays along with dual-polarized antenna elements. The antenna element achieved an efficiency of 91% and an impedance bandwidth of 1.14 GHz within a height of 10 mm at 3.7 GHz. Furthermore, the fabricated array antenna structure was tested and verified to have an effective isotropic radiated power of 75.6 dBm at boresight and a steering range of less than ±60°. Therefore, the proposed structure meets the required antenna and beam-forming performance for commercial 5G active antenna systems.

This paper proposes a novel packaging and large-scale antenna-assembled structure for a printed circuit board (PCB) that reinforces productivity, facilitates cost reduction, and maintains reliability. This was achieved by splitting the antenna from the main board and packaging it into a radio-frequency integrated circuit. In addition, two innovative solutions—an externally attachable flexible PCB antenna and a PCB-embedded coaxial line—are introduced to overcome the degradation in antenna performance and vertical RF transition loss in the proposed low-cost hybrid PCB. First, the proposed externally attachable flexible PCB antenna and a parasitic air-coupled antenna, which were easily assembled on the PCB, achieved an antenna efficiency of 95% and an impedance bandwidth of 7 GHz. Second, the fabricated coaxial line exhibited enhanced impedance matching over a wide frequency range of 30–40 GHz and improved insertion loss of approximately 1.4 dB. Furthermore, the packaged antenna, composed of 256 dual-polarized antenna elements per stream, incorporated a 39 GHz CMOS-based 16-channel phased-array transceiver IC. The set-level beam-forming measurements were verified considering an effective isotropic radiated power of 55 dBm at boresight and a steering range >±60°. In addition to being suitable for mass production in terms of cost and reliability, the proposed structures and solutions met the required antenna and beam-forming performance for commercial 39 GHz base stations without sacrificing performance.

In this paper, we present a method for obtaining the power density value, which is the standard for radio frequency (RF) electromagnetic field (EMF) human exposure from mmWave mobile devices, using a deep learning network. An mmWave mobile communication device that uses an array antenna requires a large number of phase conditions for covering a wide communication range. However, the power density values must be repeatedly obtained every time the phase conditions are changed, which incurs a lot of time and cost. For implementing the process seamlessly, we present a deep learning network that can input the phase conditions of the mmWave array antenna and simultaneously obtain the power density results for the phase conditions of the array antenna as an output. For a $4\times 1$ array patch antenna, which is commonly used in 5G mobile communication devices, the phases of the antenna were changed, and 5,832 electric and magnetic field data were acquired, which were then converted to power density values and learned thereafter. We examined whether appropriate power density values were output when inputting arbitrary phase sets of array antennas for the learned deep learning network. With the learned deep learning network, it was confirmed that when inputting unlearned phases for a $4\times 1$ array antenna, the power density values similar to the actual simulation were quickly obtained as output.

This paper presents a unified framework for Automatic Repeat reQuest (ARQ)-based retransmission schemes in multi-user broadcast environments. Two perspectives, namely, coded packet design and the enhancement of the ARQ protocol, are used to establish the unified framework. Consequently, the combined use of index coding and ARQ incorporated with memory is demonstrated to be beneficial toward performance enhancement in terms of transmission efficiency and memory overhead. Specifically, the asymptotic and finite transmission efficiencies of the index-coded ARQ incorporated with memory are analyzed to be close to the optimum over a wide range of packet error probabilities and the number of users, which is validated numerical evaluations. Furthermore, the use of index coding is analyzed to be also favourable in terms of memory overhead in comparison with the memory ARQ. Thus, index-coded ARQ with appropriate use of memory is shown to be a reasonable option in a practical sense, which sheds light on the possibility that multi-user coded ARQ can play a crucial role for a reliable broadcast beyond unicast.

When a current of ~300 A flows through a contact line that supplies power to a high-speed train traveling at maximum speed, it forms a strong magnetic field. Magnetometers - sensors that measure magnetic fields - are affected by this magnetic field around the contact line. In this study, the magnetic field formed around a contact line was measured and its effect on magnetometers was indicated. In order to confirm the degree of influence of such fields on a magnetometer, a magnetic field around a contact line was measured and simulated. For a high-speed train traveling at 300 km/h, the magnetic field was measured at 14.1 μT, 3 m away from the contact line. In addition, a magnetic field was formed when a current of 300 A flowing through the contact line was simulated in a laboratory environment. The outcome of the simulation was then compared with the measured values. This study experimentally verified the measurement error of the magnetometer caused by the contact line and confirmed that a filter can be used to reduce the error.

In this article, we propose a deep neural network (DNN)for the radiation pattern synthesis of an antenna. The DNN utilizes the radiation patterns as inputs and the amplitude and phase of the antenna elements as outputs. Consequently, the radiation patterns of the array antenna can be easily obtained from the outputs of the trained DNN, which are amplitude and phase of the antenna elements. However, it is difficult to determine the amplitude and phase of each antenna element from the desired pattern in an environment where inter-element coupling exists. For this purpose, 6,859 radiation pattern samples for a 4×1 array patch antenna were generated by changing the phases of the antenna elements, and those patterns were leveraged to train the proposed DNN with low complexity. The radiation patterns of the ideal square and triangular array shapes, which are practically infeasible to implement, were used as inputs to the DNN. It was confirmed that the radiation pattern generated from the output signals of the DNN was very similar to the input radiation pattern.

When a drone is used for inspection of facilities, there are often cases in which high-voltage power lines interfere, resulting in the drone being caught or falling. To prevent this type of incident, drones must be capable of detecting high-voltage power lines. Typically, a strong electric field is formed around the high-voltage lines. To detect the electric fields around high-voltage lines, this study proposes an electric field sensor that may be integrated within the body of a drone. In a laboratory environment, a voltage of 25 kV was applied to an overhead line, and the induced voltage in the proposed sensor was measured at various electric field intensities. Over an electric field range of 0.5 to 10.1 kV/m, a voltage of 0 to 0.77 V was measured with each proposed sensor. In addition, the electric field and the voltage induced in the sensor were measured in a real-world railway environment with overhead lines. Under these conditions, the proposed sensor has the compensated value of 4.5 when the measured electric field was 4.05 kV/m. Therefore, the proposed sensor may be applied in drones to measure large electric fields and to detect the presence of high-voltage lines in its vicinity.

We propose a deep neural network (DNN) to determine the matching circuit parameters for antenna impedance matching. The DNN determines the element values of the matching circuit without requiring a mathematical description of matching methods, and it approximates feasible solutions even for unimplementable inputs. For matching, the magnitude and phase of impedance should be known in general. In contrast, the element values of the matching circuit can be determined only using the impedance magnitude using the proposed DNN. A gamma-matching circuit consisting of a series capacitor and a parallel capacitor was applied to a conventional inverted-F antenna for impedance matching. For learning, the magnitude of input impedance S11 of the antenna was extracted according to the element values of the matching circuit. A total of 377 training samples and 66 validation samples were obtained. The DNN was then constructed considering the magnitude of impedance S11 as the input and the element values of the matching circuit as the output. During training, the loss converged as the number of epochs increased. In addition, the desired matching values for unlearned square and triangular waves were obtained during testing.

In general, a partially reflective surface (PRS) is mainly used to increase the gain of an antenna; some metallic objects placed on the PRS degrades the antenna performance because the objects change the periodic structure of the PRS. Herein, we propose a multifunctional PRS for smart block application. When a passenger passes over a smart block, the fare can be simultaneously collected and presented through the LED display. This requires high gain antenna with LED structure. The high gain characteristic helps the antenna identify passengers only when they pass over the block. The multifunctional PRS has a structure in which an LED can be placed in the horizontal direction while increasing the antenna gain. We used the antenna’s polarization characteristics to prevent performance deterioration when LED lines are placed in the PRS. We built the proposed antenna and measured its performance: At 2.41 GHz, the efficiency was 81.4%, and the antenna gain was 18.3 dBi. Furthermore, the half-power beamwidth was 18°, confirming a directional radiation pattern.

Objectives This study was conducted to investigate the relationships among job stress, job satisfaction, and mental health in marine officers. Methods The researchers gathered data on marine officers working at a harbor in Chungcheong Province, South Korea, using a self-reported questionnaire. Mental health was measured by the Symptom Checklist-90-Revision (SCL-90-R), and general characteristics including socioeconomic factors, job stress, and job satisfaction were measured by structured questionnaires. Multiple regression analysis was performed to investigate the relationships among job stress, job satisfaction, and mental health status according to the symptom dimensions of the SCL-90-R. Results Among the marine officers, obsessive-compulsive behavior, depression, and somatization were the most problematic symptoms. Those who reported poor health, low job satisfaction, and high job stress had a higher prevalence of psychoticism, somatization, depression, anxiety, and phobic anxiety. Conclusions An occupational health system should be introduced that would regularly check the mental health of marine officers in charge of ships and sailors, in order to help reduce their stress levels, enhance their job satisfaction, and thereby improve their mental health.

The high-power wireless power transfer (WPT) system in railways does not require physical contact to transfer electrical power, is electrically safe, and reduces maintenance costs from wear and tear. However, a high-power system generates a strong magnetic field that can result in problems of electromagnetic field (EMF) exposure and electromagnetic interference (EMI). In this study, EMF and EMI were measured at various positions under in-motion environment conditions for a 1-MW WPT light rail transit system. The measured maximum EMF was 2.41 μT, which is lower than the international guideline of 6.25 μT for the various locations with a potential presence of passengers. The measured EMI also satisfied international standards in the frequency range of 150 kHz–1 GHz.

A microstrip-to-slot line-fed miniaturized Vivaldi antenna using semicircular patch embedment is proposed in this study. The conventional Vivaldi antenna has ultrawide bandwidth, but suffers from low gain in the low-frequency band. The proposed antenna topology incorporates the embedment of semicircular patch elements into the side edge of the antenna. This enables the phases of electric fields at both ends of the antenna to be out of phase. Since the distance between the two ends are λL/2 where λL is the wavelength at a low operating frequency, this antenna topology can achieve the constructive addition of electrical fields at the radiating end, leading to gain enhancement at the chosen low frequency. In comparison with the conventional Vivaldi antenna, the proposed antenna has a wider bandwidth from 2.84 to 9.83 GHz. Moreover, the simulated result shows a gain enhancement of 5 dB at low frequency. This cannot be realized by the conventional low-band impedance matching techniques only relying on slotted topologies. The measured results of this proposed antenna with a size of 45 × 40 × 0.8 mm3 are in good agreement with the simulated results.

Imaging devices attached to unmanned aerial vehicles (UAVs) are used for crack measurements of railway bridges constructed for high-speed trains. This research aims to investigate track-side wind induced by high-speed trains and its effect on UAV thrust near the railway bridge. Furthermore, the characteristics of train-induced wind in three axial directions along a track, wind velocity, and the effect of train-induced wind on the UAV thrust were analyzed. This was achieved by installing 3-axis ultrasonic anemometers and a UAV thrust measurement system on top of a PSC box girder bridge. The changes in the train-induced wind velocity were monitored along the train travel, width, and height directions. The train-induced wind was measured at distances of 0.8, 1.3, 2.3, and 2.8 m away from the train’s body to analyze wind velocity based on distance. It was found that the maximum wind velocity decreased linearly as the distance from the train’s body increased. The UAV thrust increased by up to 20% and 60%, owing to train-induced wind when the leading and trailing power cars of a high-speed train passed, respectively. Thus, it is necessary to conduct further research to develop robust control and a variable pitch-propeller that can control thrust.

Background Pincer nail deformity is a transverse overcurvature of the nail. This study aimed to define the anatomical characteristics of pincer nail deformity and to evaluate the surgical outcomes. Methods A retrospective review was conducted on 20 cases of pincer nail deformity of the great toe. Thirty subjects without pincer nail deformity or history of trauma of the feet were selected as the control group. Width and height indices were calculated, and interphalangeal angles and base widths of the distal phalanx were measured with radiography. We chose the surgical treatment methods considering perfusion-related factors such as age, diabetes mellitus, kidney disease, and peripheral vascular disease. The zigzag nail bed flap method (n=9) and the inverted T incision method (n=11) were used to repair deformities. The outcomes were evaluated 6 months after surgery. Results The interphalangeal angle was significantly greater in the preoperative patient group (14.0°±3.6°) than in the control group (7.9°±3.0°) (P

Background The septal cartilage is the most useful donor site for autologous cartilage graft material in rhinoplasty. For successful nasal surgery, it is necessary to understand the developmental process of the nasal septum and to predict the amount of harvestable septal cartilage before surgery. Methods One hundred twenty-three Korean patients who underwent three-dimensional (3D) facial bone computed tomography (CT) were selected for evaluation of the midsagittal view of the nasal septum. Multiple parameters such as the area of each component of the nasal septum and the amount of harvestable septal cartilage were measured using Digimizer software. Results The area of the total nasal septum showed rapid growth until the teenage years, but thereafter no significant change throughout the lifetime. However, the development of the septal cartilage showed a gradual decline due to ossification changes with aging after puberty in spite of a lack of change in the total septal area. The area of harvestable septal cartilage in young adults was 549.84±151.26 mm2 and decreased thereafter with age. Conclusions A 3D facial bone CT scan can provide valuable information on the septal cartilage graft before rhinoplasty. Considering the developmental process of the septal cartilage identified in this study, septal surgery should not be performed until puberty due to the risk of nasal growth impairment. Furthermore, in elderly patients who show a decreased cartilage area due to ossification changes, septal cartilage harvesting should be performed carefully due to the risk of saddle nose deformity.

In this paper, we define the notion of a probability function on a poset which is similar to the probability function discussed on d-algebras, and obtain three probability functions on posets. Moreover, we define a probability realizer of a poset, and we provide some examples to describe its role for the standard probability function. We apply the notion of a probability function to the ordered plane and obtain three probability functions on it.