• ETRI Journal
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• 제44권5호
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• pp.859-874
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• 2022

This paper presents a low-power and lightweight human body communication (HBC) receiver with an embedded dummy electrode for improved signal acquisition. The clock data recovery (CDR) circuit in the receiver operates with a low supply voltage and utilizes a clock phase inversion scheme. The receiver is equipped with a main electrode and dummy electrode that strengthen the capacitive-coupled signal at the receiver frontend. The receiver CDR circuit exploits a clock inversion scheme to allow 0.9-V operation while achieving a shorter lock time than at 3.3-V operation. In experiments, a receiver chip fabricated using 130-nm complementary metal-oxide-semiconductor technology was demonstrated to successfully receive the transmitted signal when the transmitter and receiver are placed separately on each hand of the user while consuming only 4.98 mW at a 0.9-V supply voltage.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2006년도 춘계종합학술대회
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• pp.1023-1026
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• 2006

가정이나 병원 등 해상에서 위급한 환자를 모니터링 할 때 현재의 심전도 측정기의 전극센서가 불편할 경우가 많다. 구급차량 내에서나 선박에서 환자를 측정시 흔들림이 심하기 때문에 전극이 떨어져 측정이 쉽지가 않으며 또 환자의 몸에 지방분이나 습기가 많을 경우를 쉽게 붙어있지 않아 측정이 더욱 힘들어진다. 본 연구에서는 환자가 언제든지 전극을 붙이고 화장실이나 외출까지도 자유롭게 할 수가 있도록 하였으며 또 흉부에 쉽게 착용이 용이하도록 부드러운 벤드 형태로 설계되었다. 심전도의 전극소재로는 전기저항특성이 우수하고 피부 트러블이 거의 없는 금을 소재로 한 제품을 적용하였으며 광전용적맥파 및 말초체온 등을 추가로 설계하여 다중생체신호를 모니터링 할 수 있도록 구현하였다. 본 실험에서는 가승이나 늑골부위에서는 생체신호전달이 좋았으며, 환자의 복부부위에서는 생체신호가 아주 작게 검출되었다. 전극소재로 금 전극을 사용하여 일반적인 전극을 이용할 때 보다 신호 검출이 우수하다는 결과를 얻었으며. 일반적인 전극은 단순1회용으로 끝나지만 금 전극센서는 반영구적이면서도 환자가 이동시 접촉력이 우수하여 보다 정확한 데이터를 얻을 수가 있었다.

• 센서학회지
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• 제23권6호
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• pp.402-408
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• 2014

Heart rate is one of the most important signal to monitor the health condition of the patient or exerciser. Various wearable devices have been developed for the continuous monitoring of ECG signal from human body during exercise. Among these, ECG chest belt has been widely used. However wearing chest belt with ECG sensor is uncomfortable in normal life due to the electrode contact between metal electrodes of ECG sensor and skin of the human body. So we develop the royal healthcare backpack that can measure ECG signal without skin contact by using capacitor-type ECG sensor. The position of the measurement point is critical to collect a clear ECG signal in the capacitive ECG measurement from backpack. Various tests were conducted to find the optimal ECG measurement position which has less noise and could get strong and clear ECG signal during exercise, walking, hiking, mountain climbing and cycling.

• 대한의용생체공학회:의공학회지
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• 제35권6호
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• pp.234-241
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• 2014

This study was designed to investigate the effects of stimulation intensity and inter-electrode distance on the parameters of the measured sensory nerve signal. 30 healthy subjects participated in this study. Sensory nerve signals were elicited by four different pulse amplitudes, i.e., 3, 6, 9, 12 mA, with the pulse width fixed at $500{\mu}s$. The sensory nerve signals elicited by the four different pulse amplitudes were measured by four different inter-electrode distances (20, 30, 40, and 50 mm). We extracted four parameters (pulse amplitude, pulse width, pulse area, and latency time from stimulation) from the sensory nerve signals. The measured pulse amplitude and pulse width were increased when the measuring inter-electrode distance was increased while the stimulating pulse amplitude was fixed. The measured pulse amplitude was saturated with the stimulating pulse amplitudes of over 6 mA while measuring inter-electrode distance. Under the same condition, measured pulse width was increased, and sensory nerve signal was initiated early. Sensory nerve signals, specially those of pulse amplitude, were distorted by a differential amplification method that commonly measures the human body signal. The experimental results indicate that the differential amplification method is required to be replaced when measuring nerve signals. Our observations suggested that the hyperpolarization of the action potential of the sensory nerve signal for preventing distortion could be used to clarify the correlation between the parameters of the sensory nerve signals and quantification of sensations.

• 한국전기전자재료학회논문지
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• 제21권8호
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• pp.776-781
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• 2008

In this study, ubiquitous health care system attaching in chair to monitor ECG for health care was developed at the unconsciousness state. The system conveniently and simple measured ECG at non-consciousness. We measured the contact impedance to skin-electrode of metal mesh electrodes of the system. Contact impedance enable the electrode to use for ECG measurement. The results are that the impedance of the metal mesh electrodes according to sizes is low when the size is 4$cm^2$. As the result, when the size of the metal mesh electrode is 4$cm^2$, the electrode is fit for ECG measurement. We can acquired by positing the arm on the metal mesh electrode. The ECG signal was detected using a high-input-impedance bio-amplifier, and then passed filter circuitry. The measured signal transmitted to a PC through the bluetooth wireless communication and monitored. Data of the non-constrained ECG system attaching in chair is noise-data when comparing metal mesh electrode with the Ag/Agcl electrode but the data is significant to monitor ECG for check the body state.

• 대한의용생체공학회:의공학회지
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• 제29권3호
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• pp.249-253
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• 2008

The indirect-contact ECG (IDC-ECG) was introduced by a prior study for daily non-intrusive measurements. To improve the signal quality and to extend the application area of IDC-ECG, close study of the frequency characteristics of the IDC-ECG is necessary. In this study, the frequency response of the active electrode for several sample clothes was measured under conditions of actual IDC-ECG measurement with human body. Higher gain in low frequency range than expected by prior study was observed. In addition to it, wide variation in gain according to the cloth type in the low frequency range was observed. Variation in gain caused by moisture variation in the clothes was also observed. This study shows that the parallel R-C connection is proper for electrode model and the resistive factor is influenced by moisture in the clothes. This study is the first that provides the frequency response of the electrode in the actual indirect-contact ECG measurement and it is expected that the results will be helpful to improve the indirect-contact ECG method.

• 대한의용생체공학회:의공학회지
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• 제35권6호
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• pp.203-210
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• 2014

Wearable medical device has been a resurgence of interest thanks to the development of technology and propagation of smart phone in recent years. Various types of wearable devices have been introduced and available in market. Capacitive coupled electrode which measures electrocardiogram over cloth is able to be applied wearable device. In previous approaches of capacitive electrode, they need proper pressure for stable contact of the electrode to body surface. However, wearable device that gives pressure on body surface is not suitable for long-term monitoring. In this study, we proposed adhesive polyurethane-based capacitive electrode for patch-type wearable electrocardiogram (ECG) monitoring device. Self-adhesive polyurethane make the electrode and whole system be adhered to the surface of skin without any pressure. The patch-type system is consisted of analog filter, analog-to-digital converter and wireless transmission module and designed to be attached on the body as a patch. To validate the feasibility of the developed system, we measured ECG signal in stable and active state and extracted heart rate. Therefore, we observed skin response after long-term attachment for biocompatibility of the adhesive polyurethane and adhesive strength of it. The result shows the possibility of applying the developed system for ECG monitoring in real-life.

• International Journal of Control, Automation, and Systems
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• 제5권5호
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• pp.601-605
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• 2007

In this paper, we propose a simple and relative electrode contact monitoring method. By exploiting the power line interference, which is regarded as one of the worst noise sources for bio-potential measurement, the relative difference in electrode impedance can be measured without a current or voltage source. Substantial benefits, including no extra circuit components, no degradation of the body potential driving circuit, and no electrical safety problem, can be achieved using this method. Furthermore, this method can be applied to multi-channel isolated bio-potential measurement systems and home health care devices under a steady measuring environment.

• Journal of Welding and Joining
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• 제28권4호
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• pp.81-86
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• 2010

In resistance spot welding, regardless of the optimal condition, bad weld quality was still produced due to complicated manufacturing processes such as electrode wear, misalignment between the electrode and workpiece, poor part fit-up, and etc.. Therefore, the goal of this study was to measure the process signal which contains weld quality information, and to develop the process fault monitoring system. Welding force signal obtained through variety experimental conditions was analyzed and divided into three categories: good, shunt, and poor fit-up group. And then a monitoring algorithm made up of an artificial neural network that could estimate the process fault of each different category based on pattern was developed.

• 센서학회지
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• 제25권4호
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• pp.235-242
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• 2016

A system for measuring the electrodermal activity (EDA) signal occurring at the sweat glands in the left palm and left finger of the human body was implemented in this study. The EDA measurement system (EDAMS) consisted of an algometer, a biopotential measurement system (BPMS), and a PC. Two experiments were performed to evaluate the function and clinical applicability of EDAMS. First, an experiment was carried out on the linearity of the voltage and the pressure that comprised the output signals of the algometer used for applying a pressure stimulus. Second, the amplitude of the EDA signal acquired from the electrode attached to the left palm or finger was measured while increasing the pressure stimulus of the algometer. When the pressure stimulus of the algometer applied to the left scapula was increased, the amplitude of the EDA signal increased. The amplitude of the EDA signal at the left palm was observed to be greater than that at the left finger. The amplitude of the EDA signal was observed to increase in a relatively linear relation with the intensity of the pressure stimuli. In addition, the latency of the EDA signal acquired from the electrode attached to the left palm or finger was measured while increasing the pressure stimulus of the algometer. When the pressure stimulus of the algometer applied to the left scapula was increased, the latency of the EDA signal decreased. The latency of the EDA signal at the palm was observed to be less than that at the finger. The latency of the EDA signal was observed to decrease nonlinearly with the pressure stimuli.