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The global obesity epidemic has nearly doubled since 1980, and this increasing prevalence is threatening public health. It has been reported that natural products could contain potential functional ingredients that may assist in preventing obesity. Bojungchiseub-tang (BJT), mentioned in the Donguibogam as an herbal medication for the treatment of edema, a symptom of obesity, consists of eleven medicinal herbs. However, the pharmacological activity of BJT has not been investigated. The present study was designed to investigate the putative effect of BJT on the adipogenesis of 3T3-L1 cells and the weight gain of high-fat diet (HFD-) fed C57BL/6 mice. Oil Red O staining was conducted to examine the amount of lipids in 3T3-L1 adipocytes. Male C57BL/6 mice were divided into three groups: standard diet group (control, CON), 45% HFD group (HFD), and HFD supplemented with 10% of BJT (BJT). The expression levels of genes and proteins related to adipogenesis in cells, WAT, and liver were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot, respectively. We found that BJT treatment significantly decreased the protein and mRNA levels of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein α (C/EBPα), and sterol regulatory element-binding protein 1 (SREBP1) in a dose-dependent manner in differentiated 3T3-L1 cells. Similar to the results of the in vitro experiment, BJT suppressed HFD-induced weight gain in an obese mouse model. In addition, BJT effectively reduced the HFD-induced epididymal adipose tissue weight/body weight index. BJT also downregulated the mRNA levels of PPARγ, C/EBPα, and SREBP1 in the epididymal adipose and liver tissue of HFD-fed obese mice. These findings suggest that BJT induces weight loss by affecting adipogenic transcription factors. [ABSTRACT FROM AUTHOR]

A novel implantable antenna, which is compact and insensitive to the implant locations in the human body, is proposed for wireless biotelemetry in the medical device radio communications (MedRadio) service frequency band (401–406 MHz). By adopting a magneto-dielectric material as an antenna substrate, the proposed antenna can be minimized and the bandwidth of the antenna is expected to be widened enough to perform in the various implant locations within the MedRadio band. The potential of the proposed antenna aimed at biotelemetry applications was verified through simulations and measurements with a 2/3 human muscle-emulating block. The designed antenna is 20 mm × 10 mm × 1.275 mm in volume and shows the bandwidth (return loss of 10 dB) of 22.65 MHz and the maximum gain of −32 dBi at 402 MHz, which are quite competitive for the wireless biotelemetry applications. [ABSTRACT FROM AUTHOR]

There has been a remarkable interest in finding lipid inhibitors from natural products to replace synthetic compounds, and a variety of oriental medicinal herbs are reported to have biological activity with regard to lipid inhibition. Buginawa (Bugi) is a novel combined formula that contains twelve medicinal herbs with potential for weight loss induction. We hypothesized that Bugi may have antiobesity effects in 3T3-L1 preadipocytes and in a high-fat diet- (HFD-) induced mouse model. In this study, 3T3-L1 cells were treated with varied concentrations of Bugi (62.5, 125, or 250 μg/mL). Bugi treatment inhibited adipocyte differentiation by suppressing adipogenic transcription genes, including peroxisome proliferator-activated receptor γ protein (PPARγ), CCAAT/enhancer-binding protein α (C/EBPα), sterol regulatory element-binding protein 1 (SREBP1), and CCAAT/enhancer-binding protein β (C/EBPβ). Mice were fed a normal diet or an HFD for 11 weeks, and Bugi was simultaneously administered at 50 or 100 mg/kg. Bugi administration significantly reduced body weight gain and white adipose tissue (WAT) weight and effectively inhibited lipid droplet accumulation in epididymal white adipose tissue (eWAT) and liver tissue. Further, Bugi treatment suppressed mRNA levels of PPARγ, C/EBPα, and SREBP1 in eWAT and liver tissue. Our findings demonstrate that Bugi could be an effective candidate for preventing obesity and related metabolic disorders. [ABSTRACT FROM AUTHOR]

In the wireless power transfer systems, a coupling coefficient is one of the measures of performance. In particular, the coupling coefficient at critical coupling does not ensure maximum system energy efficiency but guarantee maximum output power to the load. As the coupling coefficient goes beyond the critical-coupled state, output power begins to decline. In this letter, we propose a method to maximize output power even in an overcoupled state as in the critical-coupled state by adjusting the capacitance of the resonator. Our proposal is verified by comparing the calculations and simulations with measurements, and they are in good agreement. [ABSTRACT FROM AUTHOR]

In future, it is expected that RF and infrared-based WPT technology, which are less efficient than the current WPT technology but can wirelessly transmit power over a longer distance, will become more active. Despite several decades of progress in WPT technologies, the inductive WPT system still provides a short transmission distance, as large as the transmitting/receiving coils. RF technologies have been highly anticipated as potentially being able to realize the breakthrough transmission distance. [Extracted from the article]

For an automatic recognition system, a huge number of micro-Doppler signature images is required to train a classifier. However, in general, measurements are only possible for hovering drones, so the dynamic radar cross section (RCS) of a drone with various motions is estimated through EM simulation and converted into a micro-Doppler signature image. In this work, we use far-field approximation and mesh-element rotation in the method of moments to quickly estimate the dynamic RCS of a drone in various motions. First, 3-D meshes and the impedance matrix of a single propeller are generated only once. Instead of rotating the propeller, the position information of the mesh elements is rotated without recreating 3-D meshes or the impedance matrix. Next, using the mirror-image symmetric characteristics of drone propellers and the far-field approximation, the dynamic RCS of multiple propellers is synthesized from that of a single propeller. Finally, the dynamic RCS was estimated at 3 and 9 GHz and converted to micro-Doppler signatures, spectrogram, and cadence-velocity diagram (CVD). As a result, it was more accurate to estimate the dynamic RCS at 9 GHz, and it was easier to obtain the rotation frequency at 3 GHz in the CVD. [ABSTRACT FROM AUTHOR]

In this paper, we propose a measurement method with a simple procedure based on the definition of the impedance parameter using a two-port network analyzer. The main advantage of the proposed measurement method is that there is no limit on the number of measuring coils, and the method has a simple measurement procedure. To verify the proposed method, we measured the coupling coefficient among three coils with respect to the distance between the two farthest coils at 6.78 and 13.56 MHz, which are frequencies most common for a wireless power transfer (WPT) system in high-frequency band. As a result, the proposed method showed good agreement with results of the conventional S-parameter measurement methods. [ABSTRACT FROM AUTHOR]

• No need to control Tx current for multi-Tx coils with high mutual inductance ratios. • Criteria of the high mutual inductance ratio: 0.5 or more. • Proposal of stacked Tx-coil structure for high mutual inductance ratios. • Dramatical Improvement of the transfer distance using stacked coils structure. Conventional multiple-transmitter (multi-Tx) wireless power transfer (WPT) systems require cumbersome operation in that the Tx currents need to be adjusted to be proportional to the mutual inductance between transmitting and receiving coils for optimal efficiency. In addition, planar-arranged multi-Tx systems can hardly improve the transmission distance even with fine Tx-current control. In this paper, we disclose that when the ratio of the minimum value to the maximum value of mutual inductances between Tx coils and Rx coil is 0.5 or more, multi-Tx WPT systems with identical Tx currents can achieve near-optimal efficiency. That is, under this condition, the WPT system does not need to fine-tune Tx currents. Additionally, we suggest a stacked multi-Tx system with high mutual inductance ratios that satisfies the condition. For validation of the proposed scheme, COTS coils were used to implement the single series coil, and planar multi-Tx systems as well as the stacked multi-Tx system. The experiment confirmed that the stacked multi-Tx WPT system can dramatically improve the critical transmission distance without any tuning of currents or voltages. [ABSTRACT FROM AUTHOR]

Chaff is a passive jammer widely used to disrupt radar or radio-frequency sensors. A mass of chaff fibers dispersed in the air is commonly referred to as a chaff cloud. It is nearly impossible to numerically simulate in real-time the enormous amount of chaff fibers composing the chaff cloud. In this paper, we model the behavior of numerically estimated chaff clouds as probability density functions (PDFs) and apply approximation techniques to estimate the radar cross-section (RCS) of the chaff cloud in real time. To model the aerodynamics of the chaff cloud, we represented the combination of PDFs as functions of time and wind speed. The applied approximation techniques—vector radiative transfer and generalized equivalent conductor method—showed a computation time that cannot be achieved by low-frequency methods such as the method of moments or finite-difference time-domain. Moreover, the dynamic RCS results of the approximation techniques showed a similar trend to those of other studies simulating similar situations. The proposed scheme is effective for real-time chaff cloud simulation, and the modeled dynamics and estimated dynamic RCSs can be a standard baseline for developing new analysis methods for chaff clouds. In the future, the proposed scheme will extend to more chaff fibers and more diverse environmental parameters. [ABSTRACT FROM AUTHOR]

This communication presents a microstrip comb-line array antenna for the low sidelobe level (SLL) in the millimeter wave. As the width of the conventional stub-shaped radiating element becomes wider, not only the longitudinal current but also the transverse current increases; the longitudinal and transverse currents generate the co- and cross-polarized radiation, respectively. To reduce the transverse current flows on the large-width radiating element, the width of the connecting part with the feeding line in the radiating element is narrowed. In addition, the transverse current can be further reduced by adding a notch on the top of the radiating element. These two deformed radiating elements are proposed and used to design 18-element comb-line array antennas according to the array design procedure based on the radiation conductance. The array antennas were designed for the SLL of–20 dB at 79 GHz. The prototypes are fabricated and the antenna performance was measured. From the measurement results, the comb-line antenna composed only of the conventional stub-shaped elements shows the SLL of about–16.58 dB, whereas the array antenna using the proposed elements has the SLL of–19.4 dB. This communication demonstrates the feasibility of the proposed elements for low SLL, through analysis and measurement. [ABSTRACT FROM AUTHOR]

Magnetic beamforming techniques can enhance the power transfer efficiency using focused magnetic fields by the multiple transmitters to the receivers. However, the intra-couplings that cause power leakage and phase distortion among the arrayed coils inevitably occur due to the deployment of coils having strong couplings between each other. Here, we analyze the adverse influences of intra-couplings and present the advantages of magnetically independent transmitters for multiple-inputs and single-output (MISO) WPT. The independent coil array can achieve focused magnetic fields by simply adjusting the amplitude of the transmitter voltage source without phase adjustment. The system also can eliminate the reactive power with the independent coil array to efficiently use the supplying power from the source. The analytical studies are verified by numerical and circuit simulation and experiments. Our analysis can be generalized to the MISO-WPT with an arbitrary number of transmitters. It can provide insight into designing and implementing the MISO-WPT applying magnetic beamforming. [ABSTRACT FROM AUTHOR]

Along with the increase in renewable energy, research on energy harvesting combined with piezoelectric energy is being conducted. However, it is difficult to predict the power generation of combined harvesting because there is no data on the power generation by a single piezoelectric material. Before predicting the corresponding power generation and efficiency, it is necessary to quantify the power generation by a single piezoelectric material alone. In this study, the generated power is measured based on three parameters (size of the piezoelectric ceramic, depth of compression, and speed of compression) that contribute to the deformation of a single PZT (Lead zirconate titanate)-based piezoelectric element. The generated power was analyzed by comparing with the corresponding parameters. The analysis results are as follows: (i) considering the difference between the size of the piezoelectric ceramic and the generated power, 20 mm was the most efficient piezoelectric ceramic size, (ii) considering the case of piezoelectric ceramics sized 14 mm, the generated power continued to increase with the increase in the compression depth of the piezoelectric ceramic, and (iii) For piezoelectric ceramics of all diameters, the longer the depth of deformation, the shorter the frequency, and depending on the depth of deformation, there is a specific frequency at which the charging power is maximum. Based on the findings of this study, PZT-based elements can be applied to cases that receive indirect force, including vibration energy and wave energy. In addition, the power generation of a PZT-based element can be predicted, and efficient conditions can be set for maximum power generation. [ABSTRACT FROM AUTHOR]

Typically, the actual volume of the residual limb changes over time. This causes the prosthesis to not fit, and then pain and skin disease. In this study, a prosthetic socket was developed to compensate for the volume change of the residual limb. Using an inflatable air bladder, the proposed socket monitors the pressure in the socket and keeps the pressure distribution uniform and constant while walking. The socket has three air bladders on anterior and posterior tibia areas, a latching type 3-way pneumatic valve and a portable control device. In the paper, the mechanical properties of the air bladder were investigated, and the electromagnetic analysis was performed to design the pneumatic valve. The controller is based on a hysteresis control algorithm with a closed loop, which keeps the pressure in the socket close to the initial set point over a long period of time. In experiments, the proposed prosthesis was tested through the gait simulator that can imitate a human's gait cycle. The active volume compensation of the socket was successfully verified during repetitive gait cycle using the weight loads of 50, 70, and 90 kg and the residual limb model with a variety of volumes. It was confirmed that the pressure of the residual limb recovered to the initial state through the active control. The pressure inside the socket had a steady state error of less than 0.75% even if the volume of the residual limb was changed from −7% to +7%. [ABSTRACT FROM AUTHOR]

Classifying space targets from debris is critical for radar resource management as well as rapid response during the mid-course phase of space target flight. Due to advances in deep learning techniques, various approaches have been studied to classify space targets by using micro-Doppler signatures. Previous studies have only used micro-Doppler signatures such as spectrogram and cadence velocity diagram (CVD), but in this paper, we propose a method to generate micro-Doppler signatures taking into account the relative incident angle that a radar can obtain during the target tracking process. The AlexNet and ResNet-18 networks, which are representative convolutional neural network architectures, are transfer-learned using two types of datasets constructed using the proposed and conventional signatures to classify six classes of space targets and a debris–cone, rounded cone, cone with empennages, cylinder, curved plate, and square plate. Among the proposed signatures, the spectrogram had lower classification accuracy than the conventional spectrogram, but the classification accuracy increased from 88.97% to 92.11% for CVD. Furthermore, when recalculated not with six classes but simply with only two classes of precessing space targets and tumbling debris, the proposed spectrogram and CVD show the classification accuracy of over 99.82% for both AlexNet and ResNet-18. Specially, for two classes, CVD provided results with higher accuracy than the spectrogram. [ABSTRACT FROM AUTHOR]

Radar target classification is an important task in the missile defense system. State-of-the-art studies using micro-doppler frequency have been conducted to classify the space object targets. However, existing studies rely highly on feature extraction methods. Therefore, the generalization performance of the classifier is limited and there is room for improvement. Recently, to improve the classification performance, the popular approaches are to build a convolutional neural network (CNN) architecture with the help of transfer learning and use the generative adversarial network (GAN) to increase the training datasets. However, these methods still have drawbacks. First, they use only one feature to train the network. Therefore, the existing methods cannot guarantee that the classifier learns more robust target characteristics. Second, it is difficult to obtain large amounts of data that accurately mimic real-world target features by performing data augmentation via GAN instead of simulation. To mitigate the above problem, we propose a transfer learning-based parallel network with the spectrogram and the cadence velocity diagram (CVD) as the inputs. In addition, we obtain an EM simulation-based dataset. The radar-received signal is simulated according to a variety of dynamics using the concept of shooting and bouncing rays with relative aspect angles rather than the scattering center reconstruction method. Our proposed model is evaluated on our generated dataset. The proposed method achieved about 0.01 to 0.39% higher accuracy than the pre-trained networks with a single input feature. [ABSTRACT FROM AUTHOR]

Inductive power transfer (IPT) systems have become more and more popular recently. To improve transient responses and load disturbance responses, this paper proposes a predictive controller design for a three-winding inductive power transfer (IPT) system. First, a three-winding IPT is presented. Next, a predictive controller is designed based on augmented variables and a performance index. Finally, a digital signal processor, TMS 320F2808, made by Texas Instrument, is used to execute the predictive control algorithms and to control the switching states of the power devices. An IPT system, with DC 220 V input, DC 130 V output, and a rated power of 2 kW, is implemented. A buck converter is used to provide an adjustable output voltage and output current to charge a battery set. Experimental results show that the proposed predictive controllers of the IPT system have better performance than proportional-integral (PI) controllers, including faster transient responses and better load disturbance responses. [ABSTRACT FROM AUTHOR]