Search

Purpose: This study investigates the social support in both elderly who wear hearing aids and elderly who do not report any hearing loss.Methods: The study subjects were 48 seniors age 65 or older who wore hearing aids and 48 seniors who did not wear hearing aids. A Lubben social network scales survey was conducted. The Korean Version of International Outcome Inventory for Hearing Aids, Puretone Audiometry, and Word Recognition Score tests were carried out on the elderly who were wearing hearing aids.Results: A statistical analysis represented that the total social support scores were not significantly different between the two groups. Of all the social support factors, social network was statistically significant between the groups (p < 0.05), but social support was not statistically significant. The correlation between social support and the degree of hearing loss was not statistically significant. Further, there were no significant relationships found for the social support of older adults’ wearing hearing aids and satisfaction with hearing overall, and the level of social support.Conclusion: The results of the study indicated that users hearing aid users have a smaller social network than those who do not wear hearing aids. However, this result can be interpreted as an independent factor regarding satisfaction with hearing aid use and the degree of hearing. As a follow-up study, it will be necessary to proceed to study the diversity of the background factors for those elderly who do have hearing loss.

Odor is a very serious problem worldwide. Thus, odor prediction research has been conducted consistently to help prevent odor. Odor substances that are complex odors are known, but complex odors and odor substances do not have a linear dependence. In addition, depending on the combination of odor substances, the causal relationships, such as synergy and antagonism, are different for complex odors. Research is needed to know this, but the situation is incomplete. Therefore, in this study, research was conducted through data-based research. The complex odor was predicted using various machine learning methods, and the effect of odor substances on the complex odor was verified using an explainable artificial intelligence method. In this study, according to the Malodor Prevention Act in Korea, complex odors are divided into two categories: acceptable and unacceptable. Analysis of variance and correlation analysis were used to determine the relationships between variables. Six machine learning methods (k-nearest neighbor, support vector classification, random forest, extremely randomized tree, eXtreme gradient boosting, and light gradient boosting machine) were used as predictive classification models, and the best predictive method was chosen using various evaluation metrics. As a result, the support vector machine that performed best in five out of six evaluation metrics was selected as the best model (f1-score = 0.7722, accuracy = 0.8101, sensitivity = 0.7372, specificity = 0.8656, positive predictive value = 0.8196, and negative predictive value = 0.8049). In addition, the partial dependence plot method from explainable artificial intelligence was used to understand the influence and interaction effects of odor substances.

With an increase in the demand for smart wearable systems, artificial synapse arrays for flexible neural networks have received considerable attention. A synaptic device with a two-terminal configuration is promising for complex neural networks because of its ability to scale to a crossbar array architecture. To realize practical crossbar arrays with a high density, it is essential to achieve reliable electrode lines that act as signal terminals. However, an effective method to develop intrinsically flexible signal lines in artificial neural networks has not been developed. In this study, we achieved reliable polymer signal lines for flexible neural networks using coffee ring-free micromolding in capillaries (MIMIC). In a typical MIMIC, the outward convective flow of the polymer solution inherently deteriorates the pattern fidelity. To achieve reliable conducting polymer (CP) lines, we precisely controlled the flow of the polymer solution in the MIMIC by inducing the Marangoni force. When the convective and Marangoni flows for the solution were balanced in the MIMIC, the CP line patterns were reliably produced with high fidelity. The developed CP lines exhibited superior conductivity and high mechanical flexibility. Moreover, flexible memristor arrays consisting of CP signal lines demonstrated a high potential for realizing practical neuromorphic systems linked to artificial intelligence.

Background We hypothesized utilizing machine learning (ML) algorithms for screening septic shock in ED would provide better accuracy than qSOFA or MEWS. Methods The study population was adult (≥20 years) patients visiting ED for suspected infection. Target event was septic shock within 24 h after arrival. Demographics, vital signs, level of consciousness, chief complaints (CC) and initial blood test results were used as predictors. CC were embedded into 16-dimensional vector space using singular value decomposition. Six base learners including support vector machine, gradient-boosting machine, random forest, multivariate adaptive regression splines and least absolute shrinkage and selection operator and ridge regression and their ensembles were tested. We also trained and tested MLP networks with various setting. Results A total of 49,560 patients were included and 4817 (9.7%) had septic shock within 24 h. All ML classifiers significantly outperformed qSOFA score, MEWS and their age-sex adjusted versions with their AUROC ranging from 0.883 to 0.929. The ensembles of the base classifiers showed the best performance and addition of CC embedding was associated with statistically significant increases in performance. Conclusions ML classifiers significantly outperforms clinical scores in screening septic shock at ED triage.

N-type microcrystalline silicon carbide (μc-SiC:H(n)) is a wide bandgap material that is very promising for the use on the front side of crystalline silicon (c-Si) solar cells. It offers a high optical transparency and a suitable refractive index that reduces parasitic absorption and reflection losses, respectively. In this work, we investigate the potential of hot wire chemical vapor deposition (HWCVD)–grown μc-SiC:H(n) for c-Si solar cells with interdigitated back contacts (IBC). We demonstrate outstanding passivation quality of μc-SiC:H(n) on tunnel oxide (SiO2)–passivated c-Si with an implied open-circuit voltage of 742 mV and a saturation current density of 3.6 fA/cm2. This excellent passivation quality is achieved directly after the HWCVD deposition of μc-SiC:H(n) at 250°C heater temperature without any further treatments like recrystallization or hydrogenation. Additionally, we developed magnesium fluoride (MgF2)/silicon nitride (SiNx:H)/silicon carbide antireflection coatings that reduce optical losses on the front side to only 0.47 mA/cm2 with MgF2/SiNx:H/μc-SiC:H(n) and 0.62 mA/cm2 with MgF2/μc-SiC:H(n). Finally, calculations with Sentaurus TCAD simulation using MgF2/μc-SiC:H(n)/SiO2/c-Si as front side layer stack in an IBC solar cell reveal a short-circuit current density of 42.2 mA/cm2, an open-circuit voltage of 738 mV, a fill factor of 85.2% and a maximum power conversion efficiency of 26.6%.

This paper proposes a compensation method for interpolation error of the maximum power control of a PMSM control system that generates current commands through a look-up table. A torque control system using a look-up table created through experiments has superior characteristics, such as control stability and torque accuracy, compared to a system that executes torque control via a linear controller based on modeling. However, it is impossible to generate information on all the currents for the output torque in the table. Therefore, because the data stored in the look-up table have a discrete characteristic, they are linearly interpolated to generate a current command for the torque command. However, the PMSM current trajectory is generally elliptical, which causes an error owing to linear interpolation, reducing the maximum output power. In particular, when the table data are insufficient, such as in the high-speed operation range, the reduced maximum output cannot be ignored. This paper proposes a compensation method for the interpolation error using two feedforward compensators and a PI controller, which was verified through experiments.

This paper proposes a permanent magnet synchronous machine (PMSM) table-based torque control method considering a variable DC-link voltage that can be used in a low cost DSP. The current reference generation based on two-dimensional look-up table (2D-LUT) is widely used for PMSM drives used in industrial applications because of its torque control performance and operation stability. In general, a 2D-LUT is established based on the flux and torque to overcome the variation in DC-link voltage. However, this method requires a flux estimator for estimating the instantaneous flux, which is defined as a division of the operating speed used to obtain the flux data. Therefore, to obtain the operating flux, a variable division calculation or complex controller is used, which can be difficult to process through a low cost digital signal processor. In this paper, a novel look-up table-based control method that uses the newly established speed-torque 2D-LUT is proposed. This 2D-LUT inherently implements data on the d-/q-axis currents throughout the operating regions, not only the speed and torque, but also the DC-link voltage variation. The proposed method was verified through an experiment on the torque control a variation in the DC-link voltage.

PURPOSE To develop and validate regression models to estimate maximal oxygen uptake (VO2max) from the new estimation formula based on Astrand-Ryhming step test protocol (AR protocol) in Korean male and female youths aged 13-18 years. METHODS One hundred twenty participants performed maximal graded exercise test (GXT) on a treadmill and Astrand-Ryhming step test (AR test) to measure VO2max and VO2max estimates, respectively. Participants in the validation study performed the GXT with the stationary metabolic cart and the Astrand-Ryhming step test twice for test-retest reliability. All tests were conducted at least three days apart and in a random order. RESULTS Mean calculated VO2max (40.43±11.57 mL/kg/min) from the Astrand-Ryhming step test equation was significantly low from that measured during the GXT from stationary metabolic cart (47.32±8.75 mL/kg/min, p

Highly doped p-type Si thin films are hardly etched by alkaline etchants unlike i- and n-type Si films. In addition, the use of a HNO3/HF/H2O mixture to etch p-type Si films can lead to inhomogeneous etching of p-type Si films and consequently result in excessive surface roughness and inferior surface passivation. For these reasons, we have implemented a dry etching method to selectively pattern p-type Si films for interdigitated back contact (IBC) silicon heterojunction (SHJ) solar cells using a SiO x masking layer. In this way, the underlying passivation layer and the Si surfaces can be undamaged. In this study, the etch rates of all Si films that make up IBC-SHJ solar cells have been investigated in order to obtain high etch selectivity and establish proper patterning steps. Furthermore, we have fabricated IBC-SHJ solar cells on planar wafers by using dry and wet patterning methods developed in this study. As a result, a conversion efficiency of 15.7% is obtained with V oc of 682 mV, J sc of 33.8 mA/cm2, and FF of 0.68.

This paper proposes a battery simulator (BS) based on a Z-source rectifier (ZSR), with the intention of emulating the discharge or charge characteristic of an actual lithium-polymer battery with high voltage and large capacity. The proposed BS is used for power testing for battery applications. The battery model, combined with a Shepherd model and a Thevenin model, is adopted to freely change the properties and specifications of the battery and to replicate the dynamic behavior of the battery, which is discretized to utilize the digital controller of the BS. The closed-loop voltage controller at the dc side of the ZSR is designed to emulate the rapid dynamic characteristics of the battery based on small-signal methods, considering the influence of the components of the impedance network. In this paper, battery voltage control algorithm (BVCA) is also utilized to minimize the voltage stress across switches while controlling two dc-side voltages within a wide range of output voltages. Simulation and experimental results are provided to verify the BS of the new feature and the proposed control method.

Background Although there are well-established small-animal sepsis models, the longitudinal assessment of hemodynamic variables, laboratory values, and blood culture in a single living sepsis model is limited. Therefore, we aimed to comprehensively characterize fecal peritonitis–induced sepsis in a porcine model. Materials and methods Autologous feces (1 g/kg) was administered into the peritoneum of 11 male pigs (49 ± 8 kg). The pigs were monitored up to 12 h with full fluid and vasopressor support to maintain the mean arterial pressure at >65 mm Hg. Longitudinal blood culture and laboratory values were obtained at defined time intervals. The cytokine levels in plasma were analyzed. Furthermore, a clinical registry of sepsis patients at a single emergency department was used to compare the Sepsis-related Organ Failure Assessment scores with those of the porcine model. Results The hyperdynamic phase of increasing cardiac output with decreasing systemic vascular resistance was maintained until 2 h, followed by the reverse (hypodynamic phase). With the escalating requirement for fluid and vasopressor, the lactate level progressively increased while the platelet count, urine output, and serum albumin level consistently decreased. Bacteremia developed 7 h (median) after the administration of feces, and Escherichia coli was the most common pathogen. The pattern of Sepsis-related Organ Failure Assessment scores with prominent cardiovascular failure was comparable to clinical data. Conclusions We implemented a porcine fecal peritonitis–induced sepsis model that demonstrates culture-proven bacteremia and multiple organ failure, particularly cardiovascular system failure. This model could facilitate the development of technologies for the early diagnosis of bacterial pathogens in blood.

It is necessary to obtain the rotor position of the Interior Permanent Magnet Synchronous Motor (IPMSM) for instantaneous torque control in an electric vehicle system. A resolver is mostly used as a rotor position sensor, each motor has a resolver offset according to the fit tolerance of the resolver pressed into the rotor shaft when the motor is manufactured. This resolver offset is having a huge effect on IPMSM output characteristics. Therefore, resolver offset detection equipment with a method for high precision of detection is required in production lines in order to make uniform characteristics of IPMSM. It is also necessary to have robust performance in many different kinds of the noise of equipment in the production line. This paper presents a highly precise Resolver to Digital Converter (RDC) that is implemented with LabVIEW of National Instruments and a resolver offset detecting method that has the robust performance to noise based on coordinate transformation algorithm. Experiments with and without the proposed method were performed and a comparative analysis is conducted to test the validity.

A small angle x-ray scattering simulator has been developed for metrology and inspection applications based on the first Born approximation considering non-ideal equipment-related factors. The simulator shows good reproducibility in various device structures and measurement environments, including slit-configurations and incident angles. In addition, a Q-space adaptive weighting method is proposed to enhance about 300% accuracy, especially on non-single repeated pitch structures such as VNAND with complex x-ray diffraction patterns.

In this paper, a current-fed two-inductor bi-directional DC/DC converter using resonance (CF-TIBCR) and its design method are proposed. The CF-TIBCR has characteristics of low current ripple and a high current rating because of two separated inductors. Also, it achieves zero voltage switching for all switches and zero current switching for switches of a low voltage stage by using the resonant tank. Besides, a voltage spike problem in conventional current-fed converters is solved without the need for an additional snubber or clamping circuits. As a result, the CF-TIBCR features high step-up and high efficiency. Since the proposed converter has difficulty achieving the softswitching condition when the converter requires the low voltage transfer ratio, a method that varies the number of resonant cycles is adopted to extend the output voltage range with satisfying the softswitching condition. The principles of the operation characteristics are presented with a theoretical analysis, and the proposed converter is verified through results of an experiment using a laboratory prototype.