• Proceedings of the KOSOMBE Conference
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• 대한의용생체공학회 1993년도 추계학술대회
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• pp.137-140
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• 1993

This paper describes a Chaos analyzer and its applications to characteristic analysis of ECG signals and the other signals. We can detect chaotic system among the various system by quantitative and qualitative analysis using the proposed system. And we also propose a new Possibility to recognize abnormal state of ECG signal using the chaotic characteristcs of signal.

• Proceedings of the KOSOMBE Conference
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.459-463
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• 1997

In this paper, we present the elimination of ECG artifact from the polysomnographic EEG and EOG. The idea of this method is that the ECG synchronized EEG segment is detected from ECG and regard samples of that segment a missing signal. After this, we used two interpolation methods to recover the missing segment. One is the Lagrange Polynomial Interpolation Method and the other is the Least Square Error AR Interpolation method. We tested those methods by applying to simulated signals. AR methods works well enough to reject the artifact about 10% of the main artifact level. We practically applied to real EEG and EOG signals. We also developed the algorithm to detect whether the artifact level is high or not. If the artifact level is high, then the interpolations are applied.

• Journal of Photoscience
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• 제5권2호
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• pp.73-81
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• 1998

Light signals constitute major factors in regulating gene expression and morphogenesis in plants and fungi. Phytochrome A and B were well characterized red and far-red light receptors in plants. Red light signals increased the phosphorylation of 18 kDa protein, which was identified to be nucleoside diphosphate (NDP) kinase. The NDP kinase catalyzed autophosphorylation and had a protein kinase activity similar to MAP (mitogen activated protein) kinase. As candidates for blue light photoreceptors, cDNAs for CRY1 and CRY2 were isolated. The N-teminal regions of these proteins showed a high hornology to DNA photolyase. The 120 kDa protein first detected in Pisurn sativurn, which showed blue light induced phosphorylation was also detected in Arabidopsis thaliana. The 120 kDa protein was encoded by the nphl gene, which regulated positive phototropism of the plant. In Neurospora crassa, blue light irradiation of the membrane fraction prepared from roycelia stimulated the phosphorylation of the 15 kDa protein, which was also identifmd to be an NDP kinase. Recent progress in understanding early events in light signal transduction mainly in Pisum sativum Alaska, Arabidopsis thaliana and Neurospora crassa was summarized.

• Molecules and Cells
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• 제39권1호
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• pp.6-19
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• 2016

Redox signalling comprises the biology of molecular signal transduction mediated by reactive oxygen (or nitrogen) species. By specific and reversible oxidation of redoxsensitive cysteines, many biological processes sense and respond to signals from the intracellular redox environment. Redox signals are therefore important regulators of cellular homeostasis. Recently, it has become apparent that the cellular redox state oscillates in vivo and in vitro, with a period of about one day (circadian). Circadian timekeeping allows cells and organisms to adapt their biology to resonate with the 24-hour cycle of day/night. The importance of this innate biological timekeeping is illustrated by the association of clock disruption with the early onset of several diseases (e.g. type II diabetes, stroke and several forms of cancer). Circadian regulation of cellular redox balance suggests potentially two distinct roles for redox signalling in relation to the cellular clock: one where it is regulated by the clock, and one where it regulates the clock. Here, we introduce the concepts of redox signalling and cellular timekeeping, and then critically appraise the evidence for the reciprocal regulation between cellular redox state and the circadian clock. We conclude there is a substantial body of evidence supporting circadian regulation of cellular redox state, but that it would be premature to conclude that the converse is also true. We therefore propose some approaches that might yield more insight into redox control of cellular timekeeping.

• The Korean Journal of Physiology and Pharmacology
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• 제23권4호
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• pp.237-249
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• 2019

Confirming the direct link between neural circuit activity and animal behavior has been a principal aim of neuroscience. The genetically encoded calcium indicator (GECI), which binds to calcium ions and emits fluorescence visualizing intracellular calcium concentration, enables detection of in vivo neuronal firing activity. Various GECIs have been developed and can be chosen for diverse purposes. These GECI-based signals can be acquired by several tools including two-photon microscopy and microendoscopy for precise or wide imaging at cellular to synaptic levels. In addition, the images from GECI signals can be analyzed with open source codes including constrained non-negative matrix factorization for endoscopy data (CNMF_E) and miniscope 1-photon-based calcium imaging signal extraction pipeline (MIN1PIPE), and considering parameters of the imaged brain regions (e.g., diameter or shape of soma or the resolution of recorded images), the real-time activity of each cell can be acquired and linked with animal behaviors. As a result, GECI signal analysis can be a powerful tool for revealing the functions of neuronal circuits related to specific behaviors.

• Microbiology and Biotechnology Letters
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• 제24권3호
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• pp.371-375
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• 1996

TFD is a transcription factor database which consists of short functional DNA sequences called as signals and their references. SIGNAL SCAN, developed by Dan S. Prestridge, is used to determine what signals of TFD may exist in a DNA sequence. This program searches TFD database by using a simple algorithm for character string comparison. We developed TFSCAN that aims at searching for signals in an input DNA sequence more efficently than SIGNAL SCAN. Our algorithms consist of two parts, one constructs an automata by scanning sequences of rFD, the other searches for signals through this automata. Searching for signal-related references is radically improved in time by using an indexing method. Usage of TFSCAN is very simple and its output is obvious. We developed and installed a TFSCAN input form and a CGI program in GINet Web server, to use TFSCAN. The algorithm applying automata showed drastical results in improvement of computing time. This approach may apply to recognizing several biological patterns. We have been developing our algorithm to optimize the automata and to search more sensitively for signals.

• Proceedings of the KOSOMBE Conference
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• 대한의용생체공학회 1997년도 춘계학술대회
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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.

• Journal of Biomedical Engineering Research
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• 제29권5호
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• pp.355-363
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• 2008

In order to extract only the alpha activity related signals from EEG recordings, we have applied Constrained Independent Component Analysis (cICA), a new extension of ICA in which some a priori knowledge of the alpha activity is utilized to extract only desired components. Its extraction (or filtering) performance has been compared to that of the conventional band-pass filtering via the scalp alpha power maps and cortical source maps of the alpha activity. Our results demonstrate that the alpha power maps and cortical source maps from the cICA-extracted alpha signals reveal more focalized alpha generating regions of the brain than those from the band-pass filtered alpha EEG signals. Furthermore they match more closely the activated regions of the brain mapped using fMRI, validating our results. We believe that the cICA-based filtering approach of EEG signals is a more effective means of extracting a specific brain activity reflected in EEG signals that will result in more accurate source localization or imaging maps.

• Biomedical Engineering Letters
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• 제8권4호
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• pp.345-353
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• 2018

This study suggested a new EMG-signal-based evaluation method for knee rehabilitation that provides not only fragmentary information like muscle power but also in-depth information like muscle fatigue in the field of rehabilitation which it has not been applied to. In our experiment, nine healthy subjects performed straight leg raise exercises which are widely performed for knee rehabilitation. During the exercises, we recorded the joint angle of the leg and EMG signals from four prime movers of the leg: rectus femoris (RFM), vastus lateralis, vastus medialis, and biceps femoris (BFLH). We extracted two parameters to estimate muscle fatigue from the EMG signals, the zero-crossing rate (ZCR) and amplitude of muscle tension (AMT) that can quantitatively assess muscle fatigue from EMG signals. We found a decrease in the ZCR for the RFM and the BFLH in the muscle fatigue condition for most of the subjects. Also, we found increases in the AMT for the RFM and the BFLH. Based on the results, we quantitatively confirmed that in the state of muscle fatigue, the ZCR shows a decreasing trend whereas the AMT shows an increasing trend. Our results show that both the ZCR and AMT are useful parameters for characterizing the EMG signals in the muscle fatigue condition. In addition, our proposed methods are expected to be useful for developing a navigation system for knee rehabilitation exercises by evaluating the two parameters in two-dimensional parameter space.

• Proceedings of the Microbiological Society of Korea Conference
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• 한국미생물학회 2007년도 International Meeting of the Microbiological Society of Korea
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• pp.140-140
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• 2007