• Molecules and Cells
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• 제43권4호
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• pp.397-407
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• 2020

DNAJB9 is known to be a member of the molecular chaperone gene family, whose cellular function has not yet been fully characterized. Here, we investigated the cellular function of DNAJB9 under strong mitogenic signals. We found that DNAJB9 inhibits p53-dependent oncogene-induced senescence (OIS) and induces neoplastic transformation under oncogenic RAS activation in mouse primary fibroblasts. In addition, we observed that DNAJB9 interacts physically with p53 under oncogenic RAS activation and that the p53-interacting region of DNAJB9 is critical for the inhibition of p53-dependent OIS and induction of neoplastic transformation by DNAJB9. These results suggest that DNAJB9 induces cell transformation under strong mitogenic signals, which is attributable to the inhibition of p53-dependent OIS by physical interactions with p53. This study might contribute to our understanding of the cellular function of DNAJB9 and the molecular basis of cell transformation.

• 대한의용생체공학회:의공학회지
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• 제26권4호
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• pp.199-205
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• 2005

When recording single-unit responses from neural systems, a common problem is the accurate detection of spikes (action potentials) in the presence of competing unwanted (noise) signals. While some sources of noise can be readily dealt with through filtering or 'template subtraction' techniques, other sources present a more difficult problem. In particular, noise components introduced by power supplies, which contain harmonics of the power-line frequency, can be particularly troublesome in that they can mimic the shape of the desired spikes. Thus, standard 'template subtraction' techniques or notch-filtering approaches are not appropriate. In this study, we propose the use of a novel template-subtraction scheme that involves estimating the power-line noise waveform and using cross-correlation techniques to subtract them from the recordings. This technique requires two key steps: (1) cross-correlation analysis of each recorded waveform extracts a robust representation of the power-line noise waveform and (2) a second level of cross-correlation to successfully subtract that representation from each recorded waveform. This paper describes this algorithm and provides examples of its implementation using actual recorded waveforms that are contaminated with these noise signals. An improvement (reduction) in the noise level is reported, as are suggestions for future implementation of this strategy.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.447-450
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• 1997

In this paper, the method is proposed, which enables us to assess baroreflex sensitivity noninvasively through the closed-loop feedback model between RR fluctuation and arterial blood pressure fluctuation, which are obtained in blood low signals. The proposed indexes of baroreflex sensitivity, $BRS_{LF}$ and $BRS_{HF}$, are calculated by the modulus(or gain) of the transfer unction between two fluctuations above in LF band and HF band, where the coherence is more than 0.5. To evaluate the performance of the proposed method, it is applied to blood low signals obtained from subjects at tilt angles of $0^{\circ},\;45^{\circ},\;90^{\circ}$ and $0^{\circ}$ successively. In result, it is concluded that the proposed method enables us to assess baroreflex sensitivity noninvasively.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.48-51
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• 1997

The purpose of this paper is to propose a method to protect the drowsiness of a driver. We measured the physiological signals, response time, and ace expression of the subjects in normal and drowsy state. Those data are used to establish the drowsiness index and fuzzy system. We employed the computer vision technology to extract and eye, track eyelids and measure the parameters related to drowsiness. These parameters were ed into the fuzzy system to decide the drowsiness level, When the drowsiness was detected, the fuzzy system generated warning signals which cons ist of sound and fragrance. Our system was available in decision of the drowsiness level and improvement of subjects' state.

• 대한의용생체공학회:의공학회지
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• 제26권6호
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• pp.373-381
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• 2005

The respiratory and heart beat signals are the fundamental physiological signals for sleep monitoring in the home. Using the air mattress sensor system, the respiration and heart beat movements can be measured without any harness or sensor on the subject's body which makes long term measurement difficult and troublesome. The differential measurement technique between two air cells is adopted to enhance the sensitivity. The concept of the balancing tube between two air cells is suggested to increase the robustness against postural changes during the measurement period. With this balancing tube, the meaningful frequency range could be selected by the pneumatic filter method. The mathematical model for the air mattress and balancing tube was suggested and the validation experiments were performed for step and sinusoidal input. The results show that the balancing tube can eliminate the low frequency component between two cells effectively. This technique was applied to measure the respiration and heart beat on the bed, which shows the potential applications for sleep monitoring device in home. With the analysis of the waveform, respiration intervals and heart beat intervals were calculated and compared with the signal from conventional methods. The results show that the measurement from air mattress with balancing tube can be used for monitoring respiration and heart beat in various situations.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.39-43
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• 1997

Posturography stands or quantitative assessment of body postural stability analysis. The present study developed a balance plate system to monitor patient's center of pressure (COP) movement and to analyze its stability. An equilateral triangular shaped plate was made of duralumin and forces were measured on the three vertices of the plate using industrial load cells. Specially designed electronic circuit picked up force signals ed into data acquisition system to calculate the cartesian coordinates of COP. COP calculation error was less than 2%. The force signals enabled to compute stability measures, which consisted of a variety of clinical parameters related to postural stability. Clinical experiments were carefully designed and performed on 40 normal subjects. The results were that 1) postural stability decreased with age and 2) the best parameters were those of posture deviation measures. A customized PC-based software package was developed to apply the present technique with a great convenience to monitoring and analyzing postural stability in an accurate and quantitative way.

• Journal of Photoscience
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• 제4권1호
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• pp.23-30
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• 1997

Leaf movements in nyctinastic plants are produced by changes in the turgor of extensor and flexor cells, collectively called motor cells, in opposing regions of the leaf movement organ, the pulvinus. In Samanea saman, a tropical tree of the legume family, extensor cells shrink and flexor cells swell to bend the pulvinus and fold the leaf at night, whereas extensor cells swell and flexor cells shrink to straighten the pulvinus and extend the leaf in the daytime. These changes are caused by ion fluxes primarily of potassium and chloride, across the plasma membrane of the motor cells. These ion fluxes are regulated by exogenous light signals and an endogenous biolgical clock. Inward-directed K$^+$ channels are closed in extensor and open in flexor cells in the dark period, while these channels are open in extensor and closed in flexor cells in the light period. Blue light opens the closed K$^+$ channels in extensor and closes the open them in flexor cells during darkness. Illumination of red light followed by darkness induces to open the closed K$^+$ channels in flexor and to close the open K$^+$ channels in extensor cells in the light. The dynamics of K$^+$ channels in motor cells that are controlled by light signals are consistent with the behavior of the pulvini in intact plants. Therefore, these cell types are an attractive model system to elucidate regulations of ion transports and their signal transduction pathways in plants. This review is focused on light-controlled ion movements and regulatory mechanisms involved in phosphoinositide signaling in leaf movements in nyctinastic plants.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권9호
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• pp.3559-3571
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• 2015

This paper addresses the problem of signal acquisition with a sparse representation in a given orthonormal basis using fewer noisy measurements. The authors formulate the problem statement for randomly measuring with strong signal noise. The impact of white Gaussian signals noise on the recovery performance is analyzed to provide a theoretical basis for the reasonable design of the measurement matrix. With the idea that the measurement matrix can be adapted for noise suppression in the adaptive CS system, an adapted selective compressive sensing (ASCS) scheme is proposed whose measurement matrix can be updated according to the noise information fed back by the processing center. In terms of objective recovery quality, failure rate and mean-square error (MSE), a comparison is made with some nonadaptive methods and existing CS measurement approaches. Extensive numerical experiments show that the proposed scheme has better noise suppression performance and improves the support recovery of sparse signal. The proposed scheme should have a great potential and bright prospect of broadband signals such as biological signal measurement and radar signal detection.

• 대한의용생체공학회:의공학회지
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• 제24권3호
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• pp.167-173
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• 2003

스퀴드 자력계는 외부의 배경잡음원에 대해서 매우 민감하므로 뇌자도 신호 측정을 목적으로 하는 미세 자기신호 측정에서는 배경자기잡음을 충분히 제거해야 한다. 배경잡음 제거에 일반적으로 사용되는 소프트웨어적 방법으로는 합성 미분계 및 적응필터 방법이 있다. 본 논문에서는 뇌자도 측정용으로 개발한 37채널 스퀴드 자력계에서 합성 미분계 적응필터 및 주파수 영역 적응필터를 적용하여 각각의 배경잡음 제거 효과 및 각 방법의 장단점을 살펴보고, 임상 뇌자도 측정시 상기 방법들의 선택적 적용에 관하여 논의한다

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2718-2720
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• 2002

The algorithm that can estimate frequency in real-time by using the resampling of a signal which was known frequency band like biological signals, was suggested in this study. A sinusoid signal is simulated as a practical measured signal. The sinusoid signal is sampled by using the impulse-train, and is subtracted the backward sample from forward by the sampled signals. The continuous sign, such as positive, negative or zero is counted from the calculation result of the subtraction, and those is stored. Therefore, the measured frequency is estimated by using the magnitude of continuous sign and the sampling period. The algorithm designed in this study is proven through the computer simulation.