정조운 교수

We hypothesize that our smartphone-based arrhythmia discrimination algorithm with data acquisition approach reliably differentiates between normal sinus rhythm (NSR), atrial fibrillation (AF), premature ventricular contractions (PVCs) and premature atrial contraction (PACs) in a diverse group of patients having these common arrhythmias. We combine root mean square of successive RR differences and Shannon entropy with Poincare plot (or turning point ratio method) and pulse rise and fall times to

This paper proposes a novel structural health monitoring framework for damage detection of smart structures. The framework is developed through the integration of the discrete wavelet transform, an autoregressive (AR) model, damage-sensitive features, and a support vector machine (SVM). The steps of the method are the following: (1) the wavelet-based AR (WAR) model estimates vibration signals obtained from both the undamaged and damaged smart structures under a variety of random signals; (2) a n

Lateral flow assay (LFA) technology has recently received interest in the biochemical field since it is simple, low-cost, and rapid, while conventional laboratory test procedures are complicated, expensive, and time-consuming. In this paper, we propose a robust smartphone-based analyte detection method that estimates the amount of analyte on an LFA strip using a smartphone camera. The proposed method can maintain high estimation accuracy under various illumination conditions without additional d

In this article, a nonlinear multiclass support vector machine–based structural health monitoring system for smart structures is proposed. It is developed through the integration of a nonlinear multiclass support vector machine, discrete wavelet transforms, autoregressive models, and damage-sensitive features. The discrete wavelet transform is first applied to signals obtained from both healthy and damaged smart structures under random excitations, and it generates wavelet-filtered signal. It no

Photoplethysmography (PPG) is a commonly used in determining heart rate and oxygen saturation (SpO2). However, PPG measurements and its accuracy are heavily affected by the measurement procedure and environmental factors such as light, temperature, and medium. In this paper, we analyzed the effects of different mediums (water vs. air) and temperature on the PPG signal quality and heart rate estimation. To evaluate the accuracy, we compared our measurement output with a gold-standard PPG device (

In this paper, we propose a novel strep throat detection method using a smartphone with an add-on gadget. Our smartphone-based strep throat detection method is based on the use of camera and flashlight embedded in a smartphone. The proposed algorithm acquires throat image using a smartphone with a gadget, processes the acquired images using color transformation and color correction algorithms, and finally classifies streptococcal pharyngitis (or strep) throat from healthy throat using machine le

A new medium access control (MAC) scheme embedding physical channels into multiband carrier sense multiple access/collision avoidance (CSMA/CA) networks is proposed to provide strict quality of service (QoS) guarantee to high priority users. In the proposed scheme, two priority classes of users, primary and secondary users, are supported. For primary users physical channels are provided to ensure strict QoS, whereas secondary users are provided with best-effort service using CSMA/CA modified for

In this paper, the performance of carrier-sense multiple access (CSMA)/collision-avoidance (CA) protocols in the presence of carrier-sensing errors is analyzed. Two types of carrier-sensing errors, i.e., false alarm and miss-detection, are considered, and their impact on the system performance is analyzed using a new CSMA/CA model based on a Markov chain capturing the sensing error at the physical layer. The system throughput and delay as functions of the sensing error probabilities, as well as

In this paper, we analyze the operation of ZigBee devices under the presence of WLAN interference and formulate a mathematical model for evaluating the performance of ZigBee devices. Our proposed mathematical model for ZigBee devices is based on a Markov chain concept.We here utilize the fact that the transmission power of WLAN devices is set hundred to thousand times higher than that of ZigBee devices. Thus, we assume WLAN devices interfere with ZigBee devices, but the ZigBee devices do not. Th

We hypothesize that our smartphone-based fingertip image-based heart rate detection methods reliably detect the heart rhythm and rate of subjects. We propose fingertip curve line movement-based and fingertip image intensity-based detection methods, which both use the movement of successive fingertip images obtained from smartphone cameras. To investigate the performance of the proposed methods, heart rhythm and rate of the proposed methods are compared to those of the conventional method, which

Consumers and professionals realize the importance of adopting social and environmental responsibility, but it is not easy for companies to implement transparent sustainability strategies that consumers can trust. Thus, it is often hard for consumers to compare brands to make conscious sustainability decisions. Blockchain technology is proposed as a bridge between ecolabels and industry initiatives as this technology provides the transparency of sustainable business practices. The objective of t

We have recently found that our previously-developed atrial fibrillation (AF) detection algorithm for smartphones can give false positives when subjects' fingers or hands move, as we rely on proper finger placement over the smartphone camera to collect the signal of interest. Specifically, smartphone camera pulsatile signals that are obtained from normal sinus rhythm (NSR) subjects but are corrupted by motion and noise artifacts (MNAs) are frequently detected as AF. AF and motion-corrupted episo

The apparel e-commerce industry is growing day by day. In recent times, consumers are particularly interested in an easy and time-saving way of online apparel shopping. In addition, the COVID-19 pandemic has generated more need for an effective and convenient online shopping solution for consumers. However, online shopping, particularly online apparel shopping, has several challenges for consumers. These issues include sizing, fit, return, and cost concerns. Especially, the fit issue is one of t