• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.247-247
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• 2000

A new bioelectric impedance measurement method is proposed for the precise measurement of the bioelectric impedance. To obtain the impedance from the known applied a.c. current and the measured voltage signals, a frequency conversion circuit, like the mixer in heterodyne receivers, is introduced to reduce the frequency of the original current. It can be observed from several lines of derivation that the impedance is independent on the amplitude and phase of the mixing signals. This makes it possible to use low-speed analog-to-digital converters and thus utilize cheaper electronic parts in the implementation. The possibility of the method is shown by simulations, and a generic structure applicable to bioelectric impedance measurement devices is also proposed.

• 대한예방의학회:학술대회논문집
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• 1996.10a
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• pp.153-154
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• 1996

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.955-958
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• 2005

Bioelectrical Impedance Analysis(BIA) can measure body water amount and then body fat mass. The formula is used here FFM=-4.104+0.518H+0.231W+0.130X+4.229S is used, In this work, H is height, R is resistance value, W is weight, X is reactance and S is distinction of sex.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.689-692
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• 2005

Bioelectrical Impedance Analysis(BIA) can measure body water amount and then body fat mass. Locate 4 electrode in palm to measure efficiently and flow current(50kHz, 800uA) in body for measuring voltage and capacitance. And proposed method to measure body fat with hight, weight, age and distinction of sex.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.2
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• pp.422-429
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• 2009

Meridian which used as the basic theory of acupuncture treatment, is an important functional connection system of acupuncture point in oriental medicine. Yangdorak and EAV have lack of precision because of using 2-electrode method, occurring high non-uniformed current density and electrode contact status on electrode placement spot. Therefore we implemented a meridian impedance measurement system for measuring meridian impedance using 4-electrode method. In order to confirm the precision of developed system, we made an constant current characteristic experiment using standard resistor. As a results of clinical study with 18 subjects, the meridian impedance showed that reproductivity and repeatability of HT7 acupuncture point are $0.515[k{\Omega}]{\pm}0.000$(mean${\pm}$standard deviation) and $0.515[k{\Omega}]{\pm}0.002$, respectively. And reproductivity and repeatability of PC7 are $0.521[k{\Omega}]{\pm}0.000$ and $0.521[{\Omega}]{\pm}0.001$ respectively. The proposed system was stable and reliable. Therefore this study proved AC impedance method to valid in measuring meridian impedance, and also verified precision and repeatability of the proposed meridian impedance measurement system. The proposed system will serve as more effective method of measuring meridian phenomena as a bioelectric signal in clinical practice.

• Journal of Preventive Medicine and Public Health
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• v.30 no.1 s.56
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• pp.31-43
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• 1997

Obesity usually is defined as the presence of and abnormally amount of adipose tissue. In many epidemiologic study, obesity as a health risk factor has been estimated by Body Mass Index(BMI) in general. This study was conducted to review of body fat percent measured by Bioelectric impedance analyzer as a estimator of obesity in a rural adult population. The study subjects were 421 men and 664 women who reside in the area on the Juam lake. They were sampled by multistage cluster sampling. Their mean age was 59 years old. Body fat percent increased with age, but BMI decreased with age in this study. Body fat percent was more larger at female and elder on the same BMI. The correlation coefficient between with body fat percent and body mass index was low (r=0.4737). Body fat percent was explained by not only BMI but also sex and age $(r^2=0.63)$. The result suggested that it is inadequate for BMI only to estimate obesity about elderly person who reside in the rural community. The relation of body fat percent and body mass index of this study agreed with the preceding know-ledges and studies in general.

• Journal of Chest Surgery
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• v.28 no.11
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• pp.973-976
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• 1995

The assessment method of human body composion by bioelectrical impedance is very simple, safe, rapid and noninvasive. Based on prediction formulas for total body water from bioelectrical impedance, the observed weight loss should be associated with an increase in impedance. However in edematous patients for dialysis, the calculated total body water loss as calculated from impedance were overestimated and significantly higher than the weight loss after dialysis. So determination of impedance were made in 50 edematous patients before, during and after dialysis. Mean weight loss, which was assumed to be only loss of water was 1719$\pm$ 866 gr and mean impedance change was 71.0 $\pm$ 23.0 Ohm under 50kHz. Body weight loss was highly correlated [r>0.81 with the increase in body impedance under variable frequencies[1, 10, 20, 30, 40, 50 kHz . But there were no differences between frequences. In conclusion, clinical application of bioelectrical impedance method is useful for individual edematous patients with new correlation equation[Y=230+26.8X, X;Impedance change, Y;Calculated total body water loss .

• Journal of Sensor Science and Technology
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• v.23 no.6
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• pp.368-376
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• 2014

In order to measure the segmental impedance of the body, a bioelectrical impedance measurement system (BIMS) using multi-frequency applying method and two-electrode method was implemented in this study. The BIMS was composed of constant current source, automatic gain control, and multi-frequency generation units. Three experiments were performed using the BIMS and a commercial impedance analyzer (CIA). First, in order to evaluate the performance of the BIMS, four RC circuits connected with a resistor and capacitor in serial and/or parallel were composed. Bioelectrical impedance (BI) was measured by applying multi-frequencies -5, 10, 50, 100, 150, 200, 300, 400, and 500 KHz - to each circuit. BI values measured by the BIMS were in good agreement with those obtained by the CIA for four RC circuits. Second, after measuring BI at each frequency by applying multi-frequency to the left and right forearm and the popliteal region of the body, BI values measured by the BIMS were compared to those acquired by the CIA. Third, when the distance between electrodes was changed to 1, 3, 5, 7, 9, 11, 13, and 15 cm, BI by the BIMS was also compared to BI from the CIA. In addition, BI of extracellular fluid (ECF) was measured at each frequency ranging from 10 to 500 KHz. BI of intracellular fluid (ICF) was calculated by subtracting BI of ECF measured at 500 kHZ from BI measured at seven frequencies ranging from 50 to 500 KHz. BI of ICF and ECF decreased as the frequency increased. BI of ICF sharply decreased at frequencies above 300 KHz.

• CELLMED
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• v.1 no.1
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• pp.7.1-7.9
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• 2011

Bioelectric impedance measurements have been reported to show significant variation between individuals. Different physiological conditions like thickened skin, obesity, and fluid retention can affect the impedance measurement. Therefore, it is important to learn what other factors can affect the measurements of impedance even in healthy individuals. Such information is a prerequisite for understanding the changes in impedance associated with acupuncture treatment. This study investigated the bio-impedance properties of tissue segments in the arms of a number of healthy subjects, so as to define the factors that might influence the variation of the bio-impedance data in acupuncture meridians studies. 51 healthy subjects were recruited through Liverpool Hospital, Sydney. Demographic data was collected from each subject including the age, sex, BMI, and time since most recent meal. Electrodes were applied to the forearms of each test subject. Measurements were done by a purpose-built Bio-Impedance Research Device (BIRD-I) which allowed the determination of core resistance (Rc) and core reactance (Xc) of each of the three meridian tissue segments on the anterior surface of the forearm. No significant difference was found in the core resistance attributable to age group, gender, BMI or meal intake. However, a statistically significant trend in increasing resistance from the radial to ulnar aspect of the forearm (p < 0.001) was found. No significant difference was found in the core resistance of test tissue segments among the 51 healthy subjects measured in this study. However, the trend of increasing core resistance from the radial to ulnar aspects of the arm deserves further investigation.

• Annals of Clinical Neurophysiology
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• v.13 no.2
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• pp.80-86
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• 2011

Background: A dry-type electrode is an alternative to the conventional wet-type electrode, because it can be applied without any skin preparation, such as a conductive electrolyte. However, because a dry-type electrode without electrolyte has high electrode-to-skin impedance, an impedance-converting amplifier is typically used to minimize the distortion of the bioelectric signal. In this study, we developed an active dry electroencephalography (EEG) electrode using an impedance converter, and compared its performance with a conventional Ag/AgCl EEG electrode. Methods: We developed an active dry electrode with an impedance converter using a chopper-stabilized operational amplifier. Two electrodes, a conventional Ag/AgCl electrode and our active electrode, were used to acquire EEG signals simultaneously, and the performance was tested in terms of (1) the electrode impedance, (2) raw data quality, and (3) the robustness of any artifacts. Results: The contact impedance of the developed electrode was lower than that of the Ag/AgCl electrode ($0.3{\pm}0.1$ vs. $2.7{\pm}0.7\;k{\Omega}$, respectively). The EEG signal and power spectrum were similar for both electrodes. Additionally, our electrode had a lower 60-Hz component than the Ag/AgCl electrode (16.64 vs. 24.33 dB, respectively). The change in potential of the developed electrode with a physical stimulus was lower than for the Ag/AgCl electrode ($58.7{\pm}30.6$ vs. $81.0{\pm}19.1\;{\mu}V$, respectively), and the difference was close to statistical significance (P=0.07). Conclusions: Our electrode can be used to replace Ag/AgCl electrodes, when EEG recording is emergently required, such as in emergency rooms or in intensive care units.