• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.7
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• pp.1287-1294
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• 2001

As size of waveform is very small, ECG(electrocardiogram) signal is difficult to analyze for noise which is occurred when it measures. In order to obtain ECG clearly, it must eliminate that power line interference, baseline wandering, noise of muscle constriction. In ECG, the worst problem which is recorded signal of ECG is the baseline wandering elimination, which is occurred by rhythm of respiration and muscle constriction of part from attaching to an electrode. Such the baseline is roughly irregular wandering and shaking up and down therefore the part of the baseline wandering elimination is very important because it is difficulty of ECG diagnosis. In this study, as implementation of real-time signal processing digital filter it is applicable to analyze patient's heart disease by way of design of the baseline wandering elimination system.

• Journal of Biomedical Engineering Research
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• v.21 no.6
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• pp.543-549
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• 2000

위전도(Electrogastrography, EGG)는 복부에 전극을 부착하여 위에서 발생하는 위 근육의 전기적인 활동성(gastric electrical activity)을 측정하는 방법으로, 비관혈적이며 다른 검사에 비해 측정비용이 적게 든다. 그러나 위전도 신호는 주파수가 매우 낮으며(0.2~10cpm) 진폭이 매우 작기(10~100 $\mu$V) 때문에 측정에 어려움이 있으며, 분석이 어려워 아직까지 위전도 신호해석에 대한 이론이 정립되어 있지않다. 본 연구에서는 running spectrum 분석을 이용한 4채널 위전도 시스템을 개발하여 위에서 발생하는 활동전위를 측정하였다. 본 연구에서 개발한 4채널 위전도 시스템의 4개 채널 중 가장 3 cpm 백분율이 높은 베스트 채널과, 상용화된 1채널 시스템인 Digitrapper EGG와 같은 전극부착 위치인 채널 1의 3 cpm 백분율을 비교하였다. 베스트 채널과 채널 1의 식전 평균 3 cpm 백분율은 각각 89.5%와 83.2%이었으며 통계적으로 유의하였다(p〈0.001). 식후에는 평균 3 cpm 백분율이 각각 90.4%와 76.5%이었으며 통계적으로 유의하였다(p〈0.001). 결론적으로 1채널위전도 측정기로서는 각 개인의 다양한 위의 위치를 커버할 수 없으며 그에 따른 오진을 초래할 수도 있으므로 1채널 위전도 측정기보다 4채널 위전도 측정기가 더 우수하다는 것을 확인하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.493-503
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• 2018

Recently, as living standards have improved, many people are becoming more interested in health, and self-training is increasing through exercise to prevent and manage pre-illness. In general, an imbalance of muscles causes asymmetry of posture, which can cause various diseases by accompanying an adjustment force, circulation action, displacement of internal organs, etc.. In this study, the development of fitness software that can be self - training among smart wears has attracted considerable attention in recent years. In this study, a technology was proposed for the commercialization of self - trainer fitness wear by a simulation through Android - based applications. Self - trainer fitness software was developed by combining a conductive polymer, fashion design, sewing, and electric and electronic technology to monitor the unbalance of the muscles during exercise and make smart wear that can calibrate the asymmetry by oneself. In particular, a polymer sensor was fabricated by deriving the optimal MWCNT concentration, and the electrode signal was collected by attaching the electrode to the optimal position, where the electrode signal line using the conductive fiber was designed and attached to collect the signal. A signal module that converts the bio-signals collected through electrical signal conversion and transmits them using Bluetooth communication was designed and manufactured. Self-trainer fitness software that can be commercialized was developed by combining noise cancellation with Android-based self-training application using a software algorithm method.

• Journal of Biomedical Engineering Research
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• v.25 no.5
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• pp.377-382
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• 2004

In the present study, thirteen healthy volunteers performed lumbar extension exercises at 48$^{\circ}$/s, loaded by 40, 50, 60kg(about 44, 55, 66％ of maximum voluntary contraction). During the whole period of exercises, electromyographic(EMG) signal was measured in the erector spinae muscle in order to determine muscle fatigue. Using the wavelet transform, EMG signal was separated by various frequency ranges in the time-frequency domain, and muscle fatigue was analyzed, comparing with the results based on the median frequency(MDF). MDF shifted toward the lower frequency ranges with the muscle fatigue, showing a single characteristic frequency. On the other hand, wavelet transform of EMG signals resulted in increased power amplitude in lower frequency ranges(0-125Hz), and decreased power amplitude in higher frequency ranges(375-468Hz). This study reveals that the muscle fatigue during dynamic movement is explained better by wavelet analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.10
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• pp.1345-1350
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• 2010

Sit-to-stand movement is a basic movement in daily activities. On the basis of this movement, the biomechanical functions of a person can be evaluated. The study of the joint kinematics, moment, and muscle coordination is necessary to understand the characteristics of the sit-to-stand movement. We have developed a motion-based program for inverse dynamics analysis and the electromyogram-based program for muscle force prediction. The joint kinematics and the kinetic results estimated on the basis of obtained motion data, ground reaction force, and electromyogram signals were compared with those reported in previous studies, and the muscle forces determined by the two methods were compared with each other. The methods and programs developed in this study can be used to understand biomechanics and muscle coordination involved in basic movements in daily activities.

• Journal of Biomedical Engineering Research
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• v.23 no.2
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• pp.109-117
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• 2002

Electrogastrography(EGG) is a noninvasive method for measuring gastric electrical activity on the abdomen resulting from gastric muscle. EGG signals have a very low frequency range (0.0083 ~0.15 Hz) and extremely low amplitude(10~100 uV). Consequently, EGG signal is easily influenced by other noises. Both finite impulse response(FIR) and infinite impulse response (IIR) filters need high orders or have phase distortions for passing very narrow bandwidth of the EGG signal. In this study, we decomposed EGG signals using a wavelet multiresolution method with Daubechies mother wavelet. The EGG signals were decomposed to seven levels. We reconstructed signal by summing the decomposed signals from level four to seven. To evaluate the performance of the wavelet multiresolution filter(WMF) with simulated EGG signal using two kinds of FIR and four kinds of IIR filters., we used two indices; signal to noise ratio(SNR) and reconstruction squared error(RSE). The SNR of WMF had 9.5, 6.9, and 4.7 dB bigger than that of the other filters at different noise levels, respectively. Also, The RSE of WMF had $1.22{\times}10^6, 1.16{\times}10^6, 1.02{\times}10^6$ smaller than that of the other filters at different noise levels, respectively. The WMF performed better in the SNR and RSE than two kinds of FIR and four kinds of IIR filters.

• Journal of Biomedical Engineering Research
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• v.10 no.2
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• pp.165-172
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• 1989

In this paper, the temperature dependence of tissue is estimated by measuring the attenuation coefficient and the propagation velocity of ultrasonic reflection signal. And, on the basis of expeiments, the possibility of non- invasive temperature estimation is considered. Specimens in the experiment are acryl 1)late. muscle, fat and liver of pig. The temperature of specimen is controlled by water bath which is able to adjust temperature a quarter of a degree. Through the series of experiments, we conformed that the ultrasonic parameters have lin earity to a certain extents with the change of tissue's temperature. And we expect that noninvasive temperature estimation of tissue can be realized after several preconditions be satisfied with the standard experiment conditions and a great number of base data.

• Journal of Biomedical Engineering Research
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• v.16 no.4
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• pp.507-516
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• 1995

The nonstationary identifier in the DCT domain is suggested in this study for the identification of AR parameters of above-lesion upper-trunk electromyographic (EMG) signals as a means of developing a reliable real time signal to control functional electrical stimulation (FES) in paraplegics to enable primitive walking. As paraplegic shifts his posture from one attitude to another, there is transition period where the signal is clearly nonstationary. Also as muscle fatigues, nonstationarities become more prevalent even during stable postures. So, it requires a develpment of time varying nonstationary EMG signal identifier. In this paper, time varying nonstationary EMG signals are transformed into DCT domain and the transformed EMG signals are modeled and analyzed in the transform domain. In the DCT domain, we verified reduction of condition number and increment of the smallest eigenvalue of input correlation matrix that influences numerical properties and mean square error were compared with SLS algorithm, and the proposed algorithm is implemented using IMS T-805 parallel processing computer for real time application.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2009.05a
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• pp.63-66
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• 2009

본 연구의 목표는 사용자에게 적합한 매트리스를 선택하는데 도움을 주는 신체적, 심리적 지표를 개발하고, 이를 분석하여 개인의 주관적 만족도와의 상관성을 알아보는 것이다. 시중에 판매되고 있는 5개의 매트리스의 강도를 2개씩 짝지어진 매트리스별 pared t-test를 통하여 강도별 순위를 5등급으로 분류하였다. 10명의 실험 참가자들의 신체적 지표(근전도, 심박수, 산소포화도 측정), 심리적 지표(개인 특성 설문 조사), 체압 및 주관적 만족도 측정을 실시하고, 상관분석을 통해서 이 측정결과와 개인간 주관적 만족도(선호하는 침대의 탄성)와도 일관성이 있는지 조사하였다. 연구 결과, 압력집중도(r=0.818)과 허리근육이완도(r=0.766) 그리고 심박수(r=0.670)가 주관적 만족도와 유의한 상관관계를 가지는 것으로 나타났다.

• Journal of Biomedical Engineering Research
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• v.21 no.3 s.61
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• pp.303-309
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• 2000

An accurate quantitative biomechanical evaluation for the spasticity caused by the disorder of central nervous system was made in this study. A sudden leg dropper was designed to generate objective testing environment at every trial. 3-dimensional motion analysis system(Elite. B.T.S. Italy) was used to measure kinematic data which were angle. and angular velocity of a lower limb. A program was developed to analyze the kinematic data of lower limb motion. and dynamic EMG data at the same time. To evaluate spasticity quantitatively. total 26 parameters including 14 parameters newly driven were analyzed, and statistical analysis were made for bilateral correlations. Results showed possibility to make accurate quantitative and objective evaluation for spasticity with various new parameters using new devices and program.