• Journal of the Optical Society of Korea
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• 제14권3호
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• pp.240-244
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• 2010

In this work, we used PWM sampling for demodulation of a fiber-optic interferometric current transformer. The interference signal from a fiber-optic CT is sampled with PWM triggers that produce a 90-degree phase difference between two consecutively sampled signals. The current-induced phase is extracted by applying an arctangent demodulation and a phase unwrapping algorithm to the sampled signals. From experiments using the proposed demodulation, we obtained phase measurement accuracy and a linearity error, in AC current measurements, of ~2.35 mrad and 0.18%, respectively. The accuracy of the proposed method was compared with that of a lock-in amplifier demodulation, which showed only 0.36% difference. To compare the birefringence effects of different fiber-optic sensor coils, a flint glass fiber and a standard single-mode fiber were used under the same conditions. The flint glass fiber coil with a Faraday rotator mirror showed the best performance. Because of the simple hardware structure and signal processing, the proposed demodulation would be suitable for low-cost over-current monitoring in high voltage power systems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2421-2423
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• 2005

In this paper, we introduced a LIF measurement method and summarized the theoretical side. When an altered wavelength of laser and electric power, lamp applied electric power, we measured the relative density of the metastable state in mercury after observing a laser induced fluorescence signal of 404.8nm and 546.2nm, and confirmed the horizontal distribution of plasma density in the discharge lamp. The results confirmed the resonance phenomenon regarding the energy level of atoms along a wavelength change, and also confirmed that the largest fluorescent signal in 436nm, and that the density of atoms in 546.2nm $(6^3S_1{\rightarrow }6^3P_2)$ were larger than 404.8nm $(6^3S_1{\rightarrow}6^3P_1)$. According to the increase of lamp applied electric power, plasma density increased, too. When increased with laser electric power, the LIF signal reached a saturation state in more than 2.6mJ. When partial plasma density distribution along a horizontal axis was measured using the laser induced fluorescence method, the density decreased by recombination away from the center.

• 생약학회지
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• 제50권1호
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• pp.18-24
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• 2019

Andrographolide, the main compound of Andrographis paniculata (A. paniculata), shows various biological properties including anti-viral, anti-inflammatory, anti-diabetic, and hepatoprotective effects. Our previous study has shown that A. paniculata extract exerts antiaging effects by activation of stemness in epidermal stem cells (EpSCs). In this study, we investigated the effect of andrographolide as a main compound of A. paniculata on EpSCs and its mechnism of action using several in vitro assays. Andrographolide increased the proliferation of EpSCs and induced cell cycle progression. Additionally, andrographolide increased VEGF production and the expression of stem cell markers integrin ${\beta}1$ and p63. Furthermore, phosphorylation levels of extracellular signal-regulated kinase 1/2 (ERK1/2), S6 ribosomal protein (S6RP) and Akt were increased by andrographolide. Taken together, these results indicate that andrographolide-induced proliferation of EpSCs is mediated by the ERK1/2, Akt-dependent pathway with increased production of VEGF and upregulated stemness through integrin ${\beta}1$ and p63.

• Animal Bioscience
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• 제36권3호
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• pp.429-440
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• 2023

Objective: 12-oxo-5Z,8Z,10E,14Z-eicosatetraenoic acid (12-KETE), a metabolite of arachidonic acid, is a strong candidate signal for placenta separation following calf discharge at delivery. In the present study, the effects of 12-KETE on bovine trophoblast cells were investigated to determine its function in the placentome at delivery. Methods: Bovine trophoblast cells derived from blastocysts were used. They were cocultured with or without fibroblasts derived from bovine placentome and/or bovine uterine epithelial cells. 12-KETE was added to the culture medium. Results: Bovine trophoblast cells contained binucleate cells and strongly expressed caudal type homeobox 2 (CDX-2) genes. Addition of 12-KETE to the trophoblast cell colony without feeder cells or that on a fibroblast monolayer induced rapid exfoliation of the colony. After 12-KETE addition, trophoblast cells emitted strong fluorescence caused by the degradation of dye-quenched collagen, indicating that 12-KETE activated matrix metalloproteinase of the trophoblast cells. Exfoliated cell colonies were stained with YOPRO-1, but not propidium iodide (PI). Moreover, DNA fragmentation and Bcl-2 associated X protein (Bax) gene (apoptosis stimulator) upregulation were observed in exfoliated cells, indicating that 12- KETE induced trophoblast cell apoptosis. These results were consistent with previous in vivo observations; however, even a lower concentration of 12-KETE activated trophoblast protease. Meanwhile, fibroblasts derived from the bovine placentome converted arachidonic acid to 12-KETE. Conclusion: These observations indicate that 12-KETE may serve as a signal for placenta separation at delivery.

• International Journal of Oral Biology
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• 제35권3호
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• pp.113-119
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• 2010

Porphyromonas (P.) gingivalis lipopolysaccharide (Pg LPS) is the major pathogenic component of periodontal disease. In this study, we have attempted to determine the expression profiles of the signal transduction pathway genes induced by Pg LPS in comparison with Escherichia (E.) coli LPS (Ec LPS). DC2.4 cells were treated for two hours with $1\;{\mu}g/ml$ of Pg LPS or $0.5\;{\mu}g/ml$ of Ec LPS. The total RNA from these cells was then isolated and reverse-transcribed. Gene expression profiles were then analyzed with a signal transduction pathway finder GEArray Q series kit and significant changes in expression were confirmed by real-time PCR. The microarray results indicated that several genes, including Tnfrsf10b, Vcam1, Scyb9, Trim25, Klk6, and Stra6 were upregulated in the DC2.4 cells in response to Pg LPS treatment, but were downregulated or unaffected by Ec LPS. Realtime PCR revealed that the expression of Trim25, Scyb9 and Tnfrsf10b was increased over the untreated control. Notably, Trim25 and Tnfrsf10b were more strongly induced by Pg LPS than by Ec LPS. These results provide greater insight into the signal transduction pathways that are altered by P. gingivalis LPS.

• 한국산학기술학회논문지
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• 제11권12호
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• pp.4891-4895
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• 2010

본 자기공명영상장치(MRI: Magnetic Resonance Imaging)의 구성 요소인 RF Coil의 성능은 영상의 신호대 잡음비(Signal to Noise Ratio)를 결정하는 장치이다. RF Coil의 성능은 민감도(Sensitivity)와 라디오주파수 필드 균질성(RF Field Uniformity)으로 나타내고, RF Coil에 의해 유기되는 라디오 주파수 자기장(B1 Field)의 세기는 RF Coil의 구조 및 배열에 따라 공간적으로 달라진다. MRI 신호의 크기는 RF Coil이 만들어내는 자기장의 세기에 의해 결정되기 때문에 RF Coil에 의해 형성되는 공간상의 B1 Field의 분포를 확인할 수 있어야 한다. 본 논문에서는 다채널 RF Coil 설계에 있어서 가장 기본이 되는 형태의 RF Coil 구조와 이의 B1 Field 분포를 Matlab을 이용하여 모의실험을 통해 확인 하였다. Matlab을 이용하여 계산된 기본 구조의 RF 코일이 형성하는 B1 Field 분포는 다채널 RF 코일 설계시 매우 유용하게 사용될 수 있을 것이다.

• Toxicological Research
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• 제16권1호
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• pp.63-66
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• 2000

The effects of acute ethanol on the high K+ induced $Ca^{2+}}$ signals were examined from primary cultures of cerebellar granule neurons. $Ca^{2+}}$ signals were measured with Calcium Green-1 based microscopic video imaging. Because $Ca^{2+}}$ signal was low in most of granule neurons without stimuli, high KCI was used for depolarization. In most case, acute exposure to ethanol reduced the peak amplitude of the $Ca^{2+}}$ signals, induced by high K+, even though low concentration of ethanol(2~10mM) was used and the effects lasted more than 30min. In was also possible to see differences of ethanol inhibition, i.e. the temporal pattern of $Ca^{2+}}$ signal reductions and the strength of inhibition of $Ca^{2+}}$ signals in cerebellar granule neurons. These results indicate that low concentration of ethanol has diverse actions on the $Ca^{2+}}$ signals in cerebellar granule neurons.

• Smart Structures and Systems
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• 제22권1호
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• pp.95-103
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• 2018

Active vibration control via inertial mass actuators has been shown as an effective tool to significantly reduce human-induced vertical vibrations, allowing structures to satisfy vibration serviceability limits. However, a lot of practical obstacles have to be solved before experimental implementations. This has motivated simple control techniques, such as direct velocity feedback control (DVFC), which is implemented in practice by integrating the signal of an accelerometer with a band-pass filter working as a lossy integrator. This work provides practical guidelines for the tuning of DVFC considering the damping performance, inertial mass actuator limitations, such as stroke and force saturation, as well as the stability margins of the closed-loop system. Experimental results on a full scale steel-concrete composite structure (behaves similar to a footbridge) with adjustable span are reported to illustrate the main conclusions of this work.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2001년도 제6차 학술대회 초록집
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• pp.133-133
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• 2001

Purpose： To determine the relationship between anatomical variation at A-com. artery area an hemodynamically induced aneurysm-mimicking findings on 3D-TOF MRA clinically a experimentally. Method： Sixty-two patients who had no aneurysm at A-com artery on DSA were evalua with MRA. MRA was performed with 1.5T MR machine(Vision, Siemens). Scan parameters o MRA included TR/TE/FA=30/6.4/25$\psi$$\circledR$˙¡, 512＊192 of matrix with MIP technique. The occurrence of signal defect at shoulder area of bifurcated A-com artery on MRA was evalua for the relationship between the symmetricity of bilateral ACA and the patency of A-c artery. DSA images were acquired at both ICA and VA. To analyze hemodynamical facto of signal defect, experimental studies of MRA and DSA were peformed with elastic silic phantom using conducting pulsatile pump. We also compared the results with those o computational fluid dynamics(CFD).

• 대한전기학회논문지:시스템및제어부문D
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• 제52권9호
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• pp.560-567
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• 2003

EMG recordings of the electrical activity of muscle have proved to be a valuable tool in studying muscle function and reflex activity. SP(silent period) is elicited by a electrical stimulation on the chin during isometric contraction of jaw muscle. This paper proposes a model of the inhibitory reflex mechanism of jaw muscle after electrical stimulation. The SPs of jaw muscle after a electrical stimulation to the chin were divided into SP1 and SP2. SP1 is produced by the activation of periodontal receptors. The activation of nociceptors contributes to the SP2. As a result, the EMG signal generated by a proposed a model of inhibitory reflex mechanism is similar to real both EMG signal including SP1 and SP2. The present study have shown differences of SP1 and SP2 induced by inhibitory reflex mechanism.