• Journal of Biomedical Engineering Research
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• v.30 no.4
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• pp.294-305
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• 2009

The bio signals essentially have different characteristics in each person. And the main purpose of automatic diagnosis algorithm based on bio signals focuses on discriminating differences of abnormal state from personal differences. In this paper, we propose automatic ECG diagnosis algorithm which discriminates normal heart beats from premature ventricular contraction using optimization of wavelet parameterization to solve that problem. The proposed algorithm optimizes wavelet parameter to let energy of signal be concentrated on specific scale band. We can reduce the personal differences and consequently highlight the differences coming from arrhythmia via this process. The proposed algorithm using ELM as a classifier show high discrimination performance between normal beat and PVC. From the experimental results on MIT-BIH arrhythmia database the performances of the proposed algorithm are 98.1% in accuracy, 93.0% in sensitivity, 96.4% in positive predictivity, and 0.8% in false positive rate. This results are similar or higher then results of existing researches in spite of small human intervention.

• 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.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.11
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• pp.78-81
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• 1995

In imaging the samples or human internal organs in a tube shape, general RF-probe types (that encircles a sample or places on top of the sample) are usually unsuitable for the internal imaging due to the degradation of signal-to-noise ratios(SNR's). In the present study the inside-out probes for Magnetic Resonance Imaging (MRI) have been constructed in the three different shapes such as an anti-solenoidal, a saddle and a dual surface types which are positioned as close to the area as possible by putting the probe inside the tubelike sample to improve filling factor. RF-field distributions have also been calculated depending upon the geometrical changes of anti-solenoid probes. Moreover, the performance of the inside-out probes has been checked by measuring SNR's of the images acquired. The inside-out probes constructed in this study produced better SNR's and rf-field uniformity in the area close to the probes in comparing with any other commercial probes. There is a high possibility that the constructed probes in the present study are applicable to the diagnosis of human bodies.

• Journal of Biomedical Engineering Research
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• v.38 no.6
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• pp.330-335
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• 2017

Cardiac arrest is owing to the failure of the heart that makes the blood circulation stop. Arrested blood circulation prevents the supply of the oxygen and the glucose and it results the loss of consciousness and, finally, brain death. Many public institution installed the AED for emergency treatment, but, it is not efficient when the patient is alone. In this paper, we made multiplexed wearable device for cardiac arrest detection. With this device, we measure the individual's electrocardiography, heart sound and motion. If the cardiac arrest is detected, the device make a warning horn and transmit the signal for defibrillation. We obtain 98.33% of ECG data, 94.5% of PCG data and 98.38% of IMU data accuracy for each evaluation and 93.33% accuracy for integrated evaluation.

• Journal of Biomedical Engineering Research
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• v.27 no.6
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• pp.409-417
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• 2006

Research on neural circuit is a difficult area due to complexity and inaccessibility. Due to recent developments, the research using multi-electrode array of cells or tissues has become an important research area. However, there are some difficulties to decode the submerged meaning from huge and complex neural data. Moreover, it needs a harmonic collaboration between informatics and bioscience. In this paper, we have developed a custom-designed signal processing technique for multi-electrode array measured neural responses induced by electrical stimuli to the hippocampal tissue slices of the rat brain. The raw data from hippocampal slice using the multi-electrode array system were saved in a computer. Then we estimated characteristic points in each channel and calculated the total activity. To estimate the points, we used the Polynomial Fitting Approximation Method. Using the calculated total activity, we could provide the histogram or pseudo-image matrix to help interpretation of results.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.55-58
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• 1997

In this paper we reviewed and stated the present state of our team's research of the moving-actuator type total artificial heart (MA-TAH). Especially, this paper showed new direction of researches. The integrated research of battery, telemetry, TET is required. And the real-time supervisory of the state of hemodynamic variables and MA-TAH is also needed. These requirement made us to think the supervisory control system (SCS). As functional abilities of the SCS require very high computational cost, the digital signal processor is an appropriate choice for our need.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.370-373
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• 1997

We are exposed to the various external stimuli input from the environment, which cause emotional changes based on the characteristics of the stimuli. Unfortunately there are no quantitative results on relationship between human sensibility and the characteristics of physiological signals. The objective of this study was to quantify EEG signals evoked by auditory stimulation based on the assumption that the analysis of the variability on the characteristics of the EEG waveform may provide the significant information regarding changes in psychological states of the subject. The experiment was devised with seven experimental conditions, which are control and six different types of auditory stimulation. Six subjects were used to obtain EEGs while introducing auditory stimulation. Wavelet transformation was employed to analyze the EEG signals. The results showed that the reconstructed signals at the decomposition level revealed the different energy value on the EEG signal. Also, general patterns of EEG signals in rest state compare with negative and positive stimulus were found. This study could be extended to establish an algorithm which distinguishes psychophysiological states of the subjects exposed to the auditory stimulation.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.275-278
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• 1997

Standard methods estimating the power spectral density(PSD) from an irregularly sampled cardiac event series require deriving a new evenly-spaced signal applicable to those methods. To avoid that requirement, in this study, the power spectrum of heart rate variability was estimated by Lomb-Scargle's algorithm, which is a means of obtaining PSD estimates directly from irregularly sampled timeseries observed in astronomy. To assess the performance of Lomb-Scargle algorithm in the power spectral analysis of heart rate variability, it was applied to various cardiac event series derived through integral pulse frequency modulation model(IPFM) simulation and from real ECG signals, and the resultant power spectra was compared with those obtained by a conventional method based on the FFT. In result, it is concluded that Lomb-Scargle's periodogram is very effective in the power spectral analysis of heart rate variability, especially in the presence of arrhythmia and/or dropouts of cardiac events.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.108-110
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• 1997

In MRI, gradient coils are needed for spatial selection and position coding to obtain the position information of the NMR signal. In this paper, a new design scheme for actively-shielded x, y-gradient coils, namely, a minimum-power and/or minimum-inductance design scheme using current-loop elements, has been proposed. Its utility in designing MRI gradient coils has been shown by using simulation. An actively-shielded x-gradient coil has been designed as an example and the results are presented. The design scheme seems to be useful for actively-shielded transverse gradient coils, even of non-cylindrical or of arbitrarily -selected shapes.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3654-3658
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• 2013

The synthesis of a DO3A conjugate of [(p-aniline benzothiazole)methyl]pyridine ($L^2H_3$) and its gadolinium complex of the type [$Gd(L^2)(H_2O)$] ($GdL^2$) is described. The $R_1$ relaxivity ($=4.50mM^{-1}sec^{-1}$) and kinetic inertness of $GdL^2$ compares well with those of structurally analogous Dotarem$^{(R)}$ ($R_1=3.70mM^{-1}sec^{-1}$), a typical extracellular (ECF) MRI contrast agent (CA). Yet, by comparison with Dotarem$^{(R)}$, $GdL^2$ exhibits non-covalent interactions with human serum albumin (HSA) as evidenced by the ${\varepsilon}^*$ titration curve along with in vivo MR signal enhancement in both aorta and heart. Liver-specific nature of $GdL^2$ is also observed as excretion is made through gallbladder. Most notably, $GdL^2$ further demonstrates specificity toward the MDA-MB-231 breast cancer.