• Journal of Biomedical Engineering Research
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• v.29 no.6
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• pp.436-442
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• 2008

Magnetic resonance electrical impedance tomography(MREIT) has been suggested to produce cross-sectional conductivity images of an electrically conducting object such as the human body. In most previous studies, recessed electrodes have been used to inject imaging currents into the object. An MRI scanner was used to capture induced magnetic flux density data inside the object and a conductivity image reconstruction algorithm was applied to the data. This paper reports the performance of a thin and flexible carbon-hydrogel electrode that replaces the bulky and rigid recessed electrode in previous studies. The new carbon-hydrogel electrode produces a negligible amount of artifacts in MR and conductivity images and significantly simplifies the experimental procedure. We can fabricate the electrode in different shapes and sizes. Adding a layer of conductive adhesive, we can easily attach the electrode on an irregular surface with an excellent contact. Using a pair of carbon-hydrogel electrodes with a large contact area, we may inject an imaging current with increased amplitude primarily due to a reduced average current density underneath the electrodes. Before we apply the new electrode to a human subject, we evaluated its performance by conducting MREIT imaging experiments of five swine legs. Reconstructed conductivity images of the swine legs show a good contrast among different muscles and bones. We suggest a future study of human experiments using the carbon-hydrogel electrode following the guideline proposed in this paper.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.484-487
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• 2014

In this paper, We describe antenna characteristics for efficiently detecting human signs using small, planar and low power antenna. Then we can measure biological signals including respiration, heart rate, blood pressure, and blood sugar, using UWB (Ultra Wide Band) pulses, while does not contact the human body. The antenna need stable and wideband impedance characteristic, because it use gaussian pulse signal. Usually it has trade-off between wideband impedance and gain. But we don't considered array type antennas because we want to need small size. Generally the antennas that classified as frequency independent satisfy our requirements. Frequency independent antennas include spiral, log-periodic, sinuous, and etc. These antennas are possible to have shape planar type. In this paper, We tested these kind antenna's characteristics in center frequency 5 GHz, Especially circular patch and sinuous antenna designed and analyzed.

• Fashion & Textile Research Journal
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• v.7 no.3
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• pp.315-320
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• 2005

With regard to the fact that temperature of human body remains almost constant at $37^{\circ}C$, changes by circadian variation, this study intended to investigate the effect of circadian rhythm on physiological responses of human body according to body fat rate. Fifteen healthy adult women were recruited for this study and were measured body fat as a method of bio impedance. We organized subjects into three groups ; low body fat group(group L-less than 20% of body fat), medium body fat group(group M-20%~30% of body fat) and high body fat group(group H-more than 30% of body fat). The experiment was carried out in a climate chamber of $32^{\circ}C$, 60% RH with the repeat of 'Exercise' and 'Rest' period. Subjects participated in two experiments, one is morning experiment(called 'AM'), the other is afternoon experiment (called 'PM'). The results of this study are as follows ; As to the variation of rectal temperature, group L and M had a significant difference in the time of the day between AM and PM, but group H had almost the same rectal temperature in the two kinds of experimental time. The reason why group H had a smaller difference in the circadian rhythm of rectal temperature in this study is estimated at the Budd et al.(1991)'s results that body fat had effects on reduction in thermogenesis, radiation, mean skin temperature, and increase in insulation of the tissues. Group M had the highest mean skin temperature in the 'PM'. All the 3 groups didn't have stable values in 'AM'. But it showed more stable in 'PM' than 'AM'. Sweat rate was the highest in group H in both 'AM' and 'PM'. Group M had larger sweat rate in 'PM' than 'AM'. but in group L and H, sweat rate was almost the same in two kinds of time of the day. This result suggests that who have more or less body fat have larger difference in sweat rate between morning and afternoon than who have normal body fat.

• Journal of The Korean Society of Integrative Medicine
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• v.12 no.2
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• pp.1-10
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• 2024

Purpose : Sarcopenic obesity is associated with adverse health consequences in females. Nevertheless, there has been limited research on the hazardous components and prevailing rates of sarcopenic obesity among younger women. This study aimed to identify the hazardous components and prevailing rates of sarcopenic obesity in younger females. Methods : This study utilized data based on 2008~2011 from the Korea National Health and Nutrition Examination Surveys by the centers for disease control and prevention. The analysis was concentrated on a subset of 1,520 women aged between 30 and 39 years of age. The participants answered a questionnaire to gather demographic information. They then underwent a physical examination to measure the human detention variables, which was conducted utilizing bioelectrical impedance analysis. The blood pressure and blood laboratory tests were determined using established laboratory protocols for evaluating blood parameters. Results : This study included 1,520 patients aged 30~39 years old. The mean age of the participants was 34.97 (years)±2.74 and the overall prevailing rate was 1.84 %. The hazard components in human dimensions were the height, weight, body mass index (BMI), waist circumference (WC) and skeletal muscle mass index (SMI). The hazard components in biochemical and blood pressure were high fasting glucose, increased triglyceride, elevated total cholesterol, high systolic blood pressure, and increased diastolic blood pressure with p-values <.05. Conclusion : This study examined the hazardous components and prevailing rates of sarcopenic obesity in younger women living in the community. The results contribute to the current body of knowledge on sarcopenic obesity and shed light on possible hazardous components in a younger female population. Based on these findings, there should be increased health and medical attention towards the prevention, management, and health promotion related to reducing risk factors for sarcopenic obesity in younger women.

• Journal of IKEEE
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• v.23 no.4
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• pp.1122-1127
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• 2019

In this study, the bio-impedance of the human body is able to obtain a lot of information by monitoring the pathological and physiological conditions of clinical and biological tissues. The four electrode method system for biometrics measured the potential difference between two electrodes and the other two electrodes were used as electrodes for current flow. The newly developed dry gold electrode measured impedance from 1 Hz to 50 kHz and produced reproducible results. To verify the impedance measurement of the dry electrode, the pitting was performed using an equivalent circuit model of the bioelectrode skin, and the effectiveness was demonstrated through modeling. Fixed electrode types have a constant position of the electrodes attached during the measurement, so that a stable measurement can be obtained, thereby minimizing the error.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.9
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• pp.813-821
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• 2013

In this paper, a vital signal sensor based on impedance variation of resonator is presented. Proposed vital signal sensor can detect the vital signal, such as respiration and heart-beat signal. System is composed of resonator, oscillator, surface acoustic wave (SAW) filter, and power detector. The cyclical movement of a dielectric such as a human body, causes the impedance variation of resonator within the near-field range. So oscillator's oscillation frequency variation is effected on resonator's resonant frequency. SAW filter's skirt characteristic of frequency response can be transformed a small amount of frequency deviation to a large variation. Aim to enhance the existing sensor detection range, proposed sensor operates in 870 MHz ISM band, and detect respiration and heart-beat signal at distance of 120 mm.

• Korean Journal of Acupuncture
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• v.31 no.2
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• pp.66-78
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• 2014

Objectives : The specificity of acupuncture point has been a highly controversial subject. Existing researches said that ion-distribution differences are observed on the acupuncture point. This study was conducted under the assumption that multiple ionic changes induced by muscle fatigue would be different between the acupuncture point with non-acupuncture point. Methods : To induce the identical fatigue, twenty subjects performed the knee extension/flexion exercise using the Biodex System 3. ST32 and ST33 as well as adjacent non-acupuncture points were selected. We measured blood lactate and analyzed the median frequency(MF) and peak torque. To obtain the information on the extracellular fluid(ECW), intracellular fluid(ICW) and cell membrane indirectly, we used the multi-frequency bioelectrical impedance analysis(MF-BIA) method. Results : MF, peak torque and blood lactate level of all measurement sites were gradually returned to normal. Re resistance of ST32 had a stronger response, but a non-acupuncture point adjacent to ST33 had a larger response up to 20 minutes post exercise. Ri resistances were similar for both acupoints and non-acupoints. The $C_m$ capacitance of ST32 had a stronger response after inducing fatigue, but ST33 had a smaller response than a non-acupuncture point adjacent to it. Conclusions : In comparison with before and after inducing fatigue, the specificity of acupuncture points was not clearly observed. Hence, we concluded that the body composition factors extraction method had the limitation as a method of finding the specificity of acupuncture points by inducing fatigue.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.353-354
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• 2016

본 논문은 IEC 60479 표준 "인체감전의 생리학적 현상"에 제시되어 있는 인체감전 현상에 대하여 교류환경과 직류환경에서 인체임피던스의 특성을 실험을 통하여 분석한다. 연구 결과, 적어도 상용주파수 이하에서는 IEC 60479 표준에서 제시하는 인체 임피던스 모델의 수정이 필요함을 발견하였다. 또한 도출된 실험 결과를 활용하여 직류 배전시스템의 TN 접지방식에서 인체 감전 및 설비 누전에 따른 사고에 대하여 구분동작이 가능한 직류전용 누설전류 검출(DC Residual Current Detection) 기법을 제안한다.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.501-504
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• 2006

The estimation of the work of heart can be treated as one of the most important parameters for determining the amount of circulating blood needed for harmonious metabolism in the human body. By monitoring the work of heart, one can detect increased work load of heart and start the treatment at the early stage of CHF. Thus it is necessary to estimate the work of heart. The contractility of the left ventricle, the second important parameter for representing the motion of heart, can be estimated through information on the work of heart. In this study, the modified Windkessel model, which has been used for a measure of vascular hemodynamic impedance parameters, was adapted to estimate the work of heart.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.7
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• pp.1010-1024
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• 1995

An intelligent trajectory control method that controls a direction and a average velocity for a prosthetic arm by force and direction estimations using EMG signals is proposed. 3 stage linear filters are used as a real time joint trajectory planner to minimize the impact to human body induced by arm motions and to reduce muscle fatigues. We use combination of MLP and fuzzy filter for a limb direction estimation and a time model of force for determining a cartesian trajectory control parameter. EMG signals are acquired by using a amputation simulator and 2 dimensional joystick motion. Simulation results of the proposed method show that the arm is effectively followed the desired trajectory by estimated foreces and directions. This method reduces the number of electrodes and attatched sites compared with the method using Hogan's impedance control.