• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.495-498
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• 2008

This paper describes design of a real-time, wearable reflectance pulse oximetry which is based Wireless Sensor Network. For the purpose of continuously monitoring vital signs of a human, wearable reflectance pulse oximetry is built into a wrist type that can be obtained $SpO_2$ value of patient unobtrusively. This designed $SpO_2$ module is based on a low-power 8 bit ATmega128L microcontroller operating in 3V. Low power operating $SpO_2$ module was integrated to wireless sensor node for user's health monitoring. This paper is focused on the successful integration of all these components into wearable reflectance pulse oximetry and evaluates its ability to measure patient' $SpO_2$ value. Information from this sensor was wirelessly transmitted to a base-station for storage and display purposes.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1780-1787
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• 2014

Arterial oxygen saturation ($SpO_2$) monitoring for newborns requires special attention in neonatal intensive care units (NICUs). Newborns have very low photo-plethysmogram (PPG) amplitudes and their body movements are difficult to contain. Hardware design and its associated signal processing algorithms should be robust enough so that faulty measurements can be avoided. In this study, improved designs were implemented to deal with low perfusion, motion artifact, and the influence of ambient light. Dynamic range was increased by using different LED intensities and a feedback system. To minimize the effects of motion artifact and to discard other unqualified data, four additional algorithms were used, which were based on dual-trace detection, continuity of DC level, morphology of PPG, and simultaneity check of $SpO_2$. Our $SpO_2$ system was tested with newborns with normal respiration in the NICU. Our system provided fast, real-time responses and 100% artifact detection was accomplished under 84% of $SpO_2$.

• Journal of IKEEE
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• v.18 no.1
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• pp.172-178
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• 2014

This paper describes the design technique and the method of analog front-end to measure the saturation of hemoglobin with oxygen sensor. To process the $SpO_2$ value from the sensor, the current data from the sensor should be converted into voltage domain. Designed analog front-end usually converts the current data from the sensor into voltage domain data to pass it on analog-to-digital converter called ADC with a different level of gain characteristics. This circuit was fabricated in a $0.11{\mu}m$ CMOS technology and has 4 level of gain properties. The occupied area is $0.174mm^2$.

• IEIE Transactions on Smart Processing and Computing
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• v.6 no.2
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• pp.129-132
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• 2017

A conventional pulse oximeter has high power consumption; thus, its mobility is severely limited. In this paper, we discuss the drawbacks of the existing pulse oximeters and propose a new ultra-low-power pulse oximeter that supports wireless data transmission for remotely monitoring vital signs, such as peripheral capillary oxygen saturation (SpO2) and beats per minute (BPM). We could notably reduce power consumption by using a low-frequency single clock in all well-customized modules. Also, our device is publicly certified, and thus, possibly engaged in clinical trials for commercial use.

• Journal of Oral Medicine and Pain
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• v.48 no.3
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• pp.96-105
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• 2023

Purpose: Mandibular advancement devices (MAD) are known to be insufficiently effective in all patients with obstructive sleep apnea (OSA). This study aimed to compare the treatment outcomes of MAD therapy according to OSA severity and to investigate the risk factors for the lack of response to MAD therapy. Methods: A total of 29 patients diagnosed with OSA received an adjustable two-piece MAD treatment. Sleep parameters measured with the home sleep apnea test device, including apnea-hypopnea index (AHI) and oxygen saturation (SpO₂), and daytime sleepiness using the Epworth Sleepiness Scale (ESS) were retrospectively assessed both before and after the MAD treatment. Results: The patients were classified into three groups according to AHI severity: mild (n=16, AHI<15), moderate (n=6, 15≤AHI<30), and severe OSA (n=7, AHI≥30). MAD therapy significantly improved the sleep parameters (p<0.001 for AHI and p=0.004 for minimum SpO₂) and daytime sleepiness (p<0.001 for ESS). Furthermore, successful outcomes (reduction in AHI>50% and AHI<10 events/h) were achieved in 83.3% and 71.4% of moderate and severe OSA cases, respectively. Of 13 patients with moderate and severe OSA, 10 were classified as responders and 3 as non-responders. The non-responders had significantly lower baseline value of SpO₂ (p=0.049 for average SpO₂ and p=0.007 for minimum SpO₂) and higher baseline AHI (p=0.049) than the responders. Conclusions: The results of the present study suggest that MAD is effective in the majority of patients with OSA of varying severities. The success of MAD therapy does not seem to depend solely on AHI severity. In addition to AHI, minimum SpO₂ may be a prognostic measure of the efficacy of MAD treatment in clinical dental practice.

• Journal of IKEEE
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• v.20 no.1
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• pp.115-118
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• 2016

This paper presents development of the alarm system for preventing of the lonely death of the elderly. The population of the elderly people are growing rapidly. So, Some problems is caused by the senior citizen who lives alone, because of their death alone. In this paper, we propose the alarm system that can announce the state of the elderly who live alone. The system can check the pulse and oxygen saturation continuously. If biological signals are not good, the system can announce the information of the elderly to family and neighborhood. This system is verified by SpO2 Simulator.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.578-579
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• 2015

Transmission and reflectance are two non-invasive techniques to perform pulse oximetry. This paper presents a design of reflectance-based pulse oximetry for watch-type wearable device, in which sensor and detector are located on the same surface of the body part. The basic principle of a pulse oximeter is based on the measurement of the red and infrared (IR) light absorption. Oxygenated blood has significant differences of light absorption characteristics than deoxygenated blood under red (660 nm) and infrared (940 nm) wavelength. Infrared is absorbed more by oxygenated hemoglobin than red. So the hardware implementation is included placing of the two LEDs (red and IR) with single photo-detector in the middle on the patient's wrist to get the corresponding pulsatile signals which are used to estimate the $SpO_2$.

• Journal of Sensor Science and Technology
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• v.27 no.3
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• pp.192-198
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• 2018

Pulse oximetry is a non-invasive method for monitoring how much oxygenated hemoglobin is present in the blood. The principle of pulse oximetry is based on the red infrared light adsorption characteristics of oxygenated and deoxygenated hemoglobin. Even through the convenience of a pulse oximeter, its weak signal-to-noise ratio against motion artifacts and low perfusion makes it difficult to be accepted by execs devices. Several researchers have suggested the use of an adaptive noise cancellation (ANC) algorithm. They have demonstrated that ANC is feasible for reducing the effects of motion artifacts. Masimo Corporation developed a discrete saturation transformation (DST) algorithm that uses a reference signal and ANC. In commercial devices, it is very hard to escape it because Masimo's patents are very powerful and a better method is yet to be developed. This study proposes a new method that can measure noise saturation as well as accurate oxygen saturation from signals with high motion artifacts without using ANC and DST. The proposed algorithm can extract a normal signal without noise from a signal with motion artifacts. The reference signal from a pulse oximeter simulator was used for the evaluation of our proposed algorithm and achieved good results.

• Korean Journal of Clinical Laboratory Science
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• v.43 no.4
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• pp.188-193
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• 2011

Obstructive sleep apnea (OSA) is the most common type of sleep apnea and is caused by obstruction of the upper airway. Since it is closely related to sleep parameter and body indices, the study was focused on the relationship with them. The results of polysomnography (PSG) in obstructive sleep apnea was done at ENT department of Ewha women university Mokdong hospital from March to September 2010 with 52 subjects (male 35, female 17). The leads were placed to measure electroencephalogram (EEG), electrooculogram (EOG), mandibular and anterior tibialis electromyogram (EMG), airflow in nasal and oral cavity, chest and abdominal breathing pattern, snoring sound and arterial oxygen saturation ($SpO_2$) level. From sleep parameter and body indices of adult obstructive sleep apnea compared to normal adult revealed that age (p<0.01) and snoring sound (p<0.05) were increased, stage 1 sleep (p<0.01) was increased, the deeper stages (3&4) of sleep (p<0.05) were reduced. Respiratory disturbance index (RDI) (p<0.01), mean $SpO_2$ (p<0.05) and lowest $SpO_2$ (p<0.01) were also decreased. The correlation analysis from sleep parameter and body indices of OSA showed the positive correlation with age (r=0.463, p<0.001), snoring sound (r=0.278, p<0.05), stage 1 sleep (r=0.391, p<0.01) and RDI (r=0.409, p<0.01), but showed the negative correlation with the deeper stages (3&4) of sleep (r=-0.307, p<0.05), mean $SpO_2$=(r=-0.274, p<0.05) and lowest $SpO_2$ (r=-0.392, p<0.01). This study proves that obstructive sleep apnea and indices have closed related.

• Journal of Biomedical Engineering Research
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• v.22 no.5
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• pp.431-438
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• 2001

Oxygen saturation of blood is defined as ratio of total hemoglobins density to oxyhemoglobins density And the accuracy of pulse oxymeter that measures the oxygen saturation of blood by a noninvasive method is influenced by a measuring environment, breathing and motion of patient. Especially when patient moved his arms and fingers, it is difficult to eliminate motion artifact because the motion artifact signal has features that are overlap or closed at normal signal in frequency domain. We propose the filtering method that construct the filter banks and a matched falter to improve the Problem. When experimented by the proposed method, the ratio regulation of the proposed methods has 4.1% below than an adaptive filter (39.7%) and a moving average filter (11.2%). So. the Proposed method will be able to get a stable ratio of SpO2.