Manipulating the Cathodic Modification Effect on Corrosion Resistance of High Corrosion-Resistant Titanium Alloy.

Further improving the corrosion resistance of the ASTM Grade 13 (Gr13) titanium alloy was achieved by manipulating the cathodic modification effect. The cathodic modification of Gr13 was mainly related to the TiNi precipitate, where minor Ru was contained and controlled the precipitate in terms of size and distribution, which could manipulate the cathodic modification effect. Parameters such as temperature and cooling rate during the recrystallization process were designed to control precipitation behavior, where the temperature at 850 °C was selected to allow the full dissolution of the TiNi precipitate.

Blood pressure estimation and its recalibration assessment using wrist cuff blood pressure monitor.

The rapid evolution of wearable technology in healthcare sectors has created the opportunity for people to measure their blood pressure (BP) using a smartwatch at any time during their daily activities. Several commercially-available wearable devices have recently been equipped with a BP monitoring feature. However, concerns about recalibration remain.

Effect of Iron Content on Corrosion Properties of Pure Titanium as Grain Refiner.

Microstructures and corrosion properties of pure titanium were characterized when iron was used as a grain refiner. The added Fe element acted as a strong grain refiner for pure titanium by forming β Ti phase at grain boundaries, and 0.15 wt% Fe was revealed to be a sufficient amount to make the grain size of pure titanium below 20 μm, which was the requirement for the desired titanium cathode.

Beat-to-Beat Continuous Blood Pressure Estimation Using Bidirectional Long Short-Term Memory Network.

Continuous blood pressure (BP) monitoring is important for patients with hypertension. However, BP measurement with a cuff may be cumbersome for the patient. To overcome this limitation, various studies have suggested cuffless BP estimation models using deep learning algorithms.

Incidence of intussusception before and after the introduction of rotavirus vaccine in Korea.

Background: Recent studies have reported that after the introduction of rotavirus vaccine the incidence of intussusception did not change among infants, or slightly increased at the age immediately after the first dose. The rotavirus vaccines were introduced in Korea for private market use in 2007-2008. We investigated the incidence of intussusception before (2002-2006) and after (2009-2015) the vaccine introduction in Korea.

End-to-End Deep Learning Architecture for Continuous Blood Pressure Estimation Using Attention Mechanism.

Blood pressure (BP) is a vital sign that provides fundamental health information regarding patients. Continuous BP monitoring is important for patients with hypertension. Various studies have proposed cuff-less BP monitoring methods using pulse transit time.

Optimal Lead Position in Patch-Type Monitoring Sensors for Reconstructing 12-Lead ECG Signals with Universal Transformation Coefficient.

The aim of this study was to reconstruct a 12-lead electrocardiograph (ECG) with a universal transformation coefficient and find the appropriate electrode position and shape for designing a patch-type ECG sensor. A 35-channel ECG monitoring system was developed, and 14 subjects were recruited for the experiment. A feedforward neural network with one hidden layer was applied to train the transformation coefficient.

An Instant Donning Multi-Channel EEG Headset (with Comb-Shaped Dry Electrodes) and BCI Applications.

We developed a new type of electroencephalogram (EEG) headset system with comb-shaped electrodes that enables the wearer to quickly don and utilize it in daily life. Two models that can measure EEG signals using up to eight channels have been implemented. The electrodes implemented in the headsets are similar to a comb and are placed quickly by wiping the hair (as done with a comb) using the headset.

Effect of Intermetallic Compound Formation in Friction Welded Al Alloy Rods.

This study was carried out to evaluate the development of microstructures and mechanical properties on friction welded dissimilar materials with a light weight. For this work, Al6063 and Duralumin alloys with a shape of rod were selected as experimental materials, and friction welding was performed under conditions with a rotation speed of 2,000 RPM, a friction load of 12 kgf/cm2 and an upset force of 25 kgf/cm2, respectively. After welding, the microstructural analysis such as the grain boundary characteristic distributions and the formation of intermetallic compounds was analyzed by electron back-scattering diffraction method and transmission electron microscopy, respectively.

Effects of Intermetallic Compound Formation in Al/Cu Clad Material Fabricated by Differential Speed Rolling.

In this study, the microstructure and mechanical property of Al/Cu clad material fabricated by differential speed rolling at room temperature were evaluated. Al and Cu plates were prepared and mechanically cladded at a differential speed ratio of 2:1 between the upper and lower rolls. Post- heat-treatment was carried out after the mechanical cladding at 400 °C for 60 min to induce the formation of intermetallic compound layers at the bonded interface of Al/Cu.

Heart rate variability in patients with major depressive disorder and healthy controls during non-REM sleep and REM sleep.

The objectives of this study are to investigate heart rate variability (HRV) in major depressive disorder patients (MDD) and healthy controls during different sleep stages, and to examine the association of HRV during sleep and depression severity. Polysomnography was recorded from 15 depressive patients with a higher beck depression inventory index (BDI > 25, H-BDI-D), 15 depressive patients with a lower BDI index (BDI ≤ 25, L-BDI-D) and 15 healthy controls. HRV was calculated during the first three rapid eye movements (REM) periods and non-REM stages (i.

ECG authentication in post-exercise situation.

Human authentication based on electrocardiogram (ECG) has been a remarkable issue for recent ten years. This paper proposed an authentication technology with the ECG data recorded after the harsh exercise. 55 subjects voluntarily attended to this experiment.

Sinabro: A Smartphone-Integrated Opportunistic Electrocardiogram Monitoring System.

In our preliminary study, we proposed a smartphone-integrated, unobtrusive electrocardiogram (ECG) monitoring system, Sinabro, which monitors a user's ECG opportunistically during daily smartphone use without explicit user intervention. The proposed system also monitors ECG-derived features, such as heart rate (HR) and heart rate variability (HRV), to support the pervasive healthcare apps for smartphones based on the user's high-level contexts, such as stress and affective state levels. In this study, we have extended the Sinabro system by: (1) upgrading the sensor device; (2) improving the feature extraction process; and (3) evaluating extensions of the system.

Estimation of sleep posture using a patch-type accelerometer based device.

In this study, we developed a sleep posture estimation algorithm using 3-axis accelerometer signals measured from a patch-type sensor. Firstly, we inspected the characteristics of accelerometer signals for different sleep postures. Based on the results, we established decision rules to estimate 5 postures containing supine, left, right lateral, prone postures, and non-sleep postures such as sitting and standing.

ROI analysis for remote photoplethysmography on facial video.

As wide spreading of camera-equipped devices to the daily living environment, there are enormous opportunities to utilize the camera-based remote photoplethysmography (PPG) for daily physiological monitoring. In the camera-based remote PPG (rPPG) monitoring, the region of interest (ROI) is related to the signal quality and the computational load for the signal extraction processing. Designating the best ROI on the body while minimizing its size is essential for computationally efficient rPPG extraction.

Heart rate estimation from facial photoplethysmography during dynamic illuminance changes.

Camera-based remote photoplethysmography (rPPG) enables low-cost, non-contact cardiovascular activity monitoring. However, applying rPPG to practical use has some limitations caused from the artifacts by illuminance changes. During watching a video in a dark room, for example, watching a TV at night without illuminance, there is a high correlation between the brightness changes of a video and the illuminance variation on the skin of the viewer's face.

Highly wearable galvanic skin response sensor using flexible and conductive polymer foam.

Owing to advancements in daily physiological monitoring technology, diverse healthcare applications have emerged recently. The monitoring of skin conductance responses has extensive feasibility to support healthcare applications such as detecting emotion changes. In this study, we proposed a highly wearable and reliable galvanic skin response (GSR) sensor that measures the signals from the back of the user.

Unobtrusive monitoring of ECG-derived features during daily smartphone use.

Heart rate variability (HRV) is known to be one of the representative ECG-derived features that are useful for diverse pervasive healthcare applications. The advancement in daily physiological monitoring technology is enabling monitoring of HRV in people's everyday lives. In this study, we evaluate the feasibility of measuring ECG-derived features such as HRV, only using the smartphone-integrated ECG sensors system named Sinabro.

Estimation of body temperature rhythm based on heart activity parameters in daily life.

Body temperature contains valuable health related information such as circadian rhythm and menstruation cycle. Also, it was discovered from previous studies that body temperature rhythm in daily life is related with sleep disorders and cognitive performances. However, monitoring body temperature with existing devices during daily life is not easy because they are invasive, intrusive, or expensive.

Gender and measuring-position differences in the radial pulse of healthy individuals.

In this research, radial pulse differences according to gender and measuring positions in healthy individuals were investigated in an objective manner. A total of 372 healthy volunteers (189 males and 183 females) participated in this study. The radial pulse was measured at six different measuring positions using a multistep tonometry system.

CardioGuard: a brassiere-based reliable ECG monitoring sensor system for supporting daily smartphone healthcare applications.

We propose CardioGuard, a brassiere-based reliable electrocardiogram (ECG) monitoring sensor system, for supporting daily smartphone healthcare applications. It is designed to satisfy two key requirements for user-unobtrusive daily ECG monitoring: reliability of ECG sensing and usability of the sensor. The system is validated through extensive evaluations.

Ballistocardiography and seismocardiography: a review of recent advances.

In the past decade, there has been a resurgence in the field of unobtrusive cardiomechanical assessment, through advancing methods for measuring and interpreting ballistocardiogram (BCG) and seismocardiogram (SCG) signals. Novel instrumentation solutions have enabled BCG and SCG measurement outside of clinical settings, in the home, in the field, and even in microgravity. Customized signal processing algorithms have led to reduced measurement noise, clinically relevant feature extraction, and signal modeling.

Earth-Abundant Cobalt Pyrite (CoS2) Thin Film on Glass as a Robust, High-Performance Counter Electrode for Quantum Dot-Sensitized Solar Cells.

We report a cobalt pyrite (cobalt disulfide, CoS2) thin film on glass as a robust, high-performance, low-cost, earth-abundant counter electrode for liquid-junction quantum dot-sensitized solar cells (QDSSCs) that employ the aqueous sulfide/polysulfide (S(2-)/Sn(2-)) redox electrolyte as the hole-transporting medium. The metallic CoS2 thin film electrode is prepared via thermal sulfidation of a cobalt film deposited on glass and has been characterized by powder X-ray diffraction and electron microscopy. Using the CoS2 counter electrode, CdS/CdSe-sensitized QDSSCs display improved short-circuit photocurrent density and fill factor, achieving solar light-to-electricity conversion efficiencies as high as 4.