• The Korean Journal of Pain
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• v.20 no.2
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• pp.116-122
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• 2007

Background: Lumbar zygapophysial joints are a common source of chronic lower back pain and radiofrequency thermocoagulation (RF) of the medial branches (MB) has been shown to be effective at providing substantial pain relief for chronic low back pain. Therefore, we carried out this study to determine the short term outcomes and prognostic factors of RF on the MB of patients with lumbar facet syndrome. Methods: We performed RF in fourteen patients who showed greater than 80% pain relief up to three times after a diagnostic MB block was conducted using 0.3 ml of 0.5% bupivacaine. Using 10 cm curved electrodes with 10-mm active tip, a 60 second, $80^{\circ}C$ lesion was made after electrical stimulation at 50 Hz for sensory and 2 Hz for motor nerve testing. The degree of pain relief was then assessed after 2 weeks, and again after 3 months using a visual analog scale (VAS) and a four point Likert scale. The outcome was regarded as 'success' if at least a 50% reduction in the VAS was observed. Possible prognostic factors between the two groups were also evaluated Results: The success rate was 71.4% (10/14) after three months of follow-up. However, there were transient complications, such as neuritis like syndrome, in 4 patients. In addition, short symptom duration and low minimal voltage (< 0.4 V) for sensory stimulation were shown to be the relevant prognostic factors for a successful outcome. Conclusions: RF may be an alternative to repeated MB block or intraarticular injection for palliation of lumbar facet syndrome. For better outcomes, early diagnosis and strict patient selection should be coupled with efforts to avoid anatomically incorrect RF.

• Journal of radiological science and technology
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• v.40 no.4
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• pp.533-542
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• 2017

In diagnostic radiology, the imaging system has been changed from film/screen to digital system. However, the method for removing scatter radiation such as anti-scatter grid has not kept pace with this change. Therefore, authors have devised the indirect flat panel detector (FPD) system with net-like lead in substrate layer which can remove the scattered radiation. In clinical context, there are many radiographic examinations with angulated incident X-ray. However, our proposed FPD has net-like lead foil so the vertical lead foil to the angulate incident X-ray would have bad effect on its performance. In this study, we identified the effect of vertical/horizontal lead foil component on the novel system's performance and improved the structure of novel system for clinical usage with angulated incident X-ray. Grid exposure factor and image contrast were calculated to investigate various structure of novel system using Monte Carlo simulation software when the incident X-ray was tilted ($0^{\circ}$, $15^{\circ}$, and $30^{\circ}$ from the detector plane). More photons were needed to obtain same image quality in the novel system with vertical lead foil only then the system with horizontal lead foil only. An optimal structure of novel system having different heights of its vertical and horizontal lead foil component showed improved performance compared with the novel system in a previous study. Therefore, the novel system will be useful in a clinical context with the angulated incident X-ray if the height and direction of lead foil in the substrate layer are optimized as the condition of conventional radiography.

• Korean Journal of Materials Research
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• v.8 no.4
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• pp.288-292
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• 1998

The p*-n ultra shallow junction diode with Co/Ti bilayer silicide was formed by ion implantation of $BF_{2}$ energy : 30KeV, dose : $5\times10^{15}cm^{-2}$] onto the n-well Si(100) region and RTA-silicidation of the evaporated Co($120\AA$)/Ti($40\AA$) double layer. The fabricated diode exhibited ideality factor of 1.06, specific contact resistance of $1.2\times10^{-6}\Omega\cdot\textrm{cm}^2$ and leakage current of $8.6\muA/\textrm{cm}^2$(-3V) under the reverse bias of 3V. The sheet resistance of silicided emitter region, the boron concentration at silicide/Si interface and the junction depth including silicide layer of ($500\AA$ were about $8\Omega\Box$, $6\times10^{19}cm^{-3}$, and $0.14\mu{m}$, respectively. In the fabrication of diode, the application of Co/Ti bilayer silicide brought improvement of ideality factor on the current-voltage characteristics as well as reduction of emitter sheet resistance and specific contact resistance, while it led to a little increase of leakage current.

• Journal of the Korean Society of Radiology
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• v.7 no.4
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• pp.307-311
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• 2013

This study examined the change of artifact volume by analyzing the level of image change associated with the setting of threshold through 3D imaging in scan parameter(slice thickness and helical pitch) and 3D image reconstruction to explore whether the presence of pathology was fully distinguished when CT was taken by lower dose than the existent dose to reduce exposure. Furthermore, this study attempted to investigate Scan Parameter acceptable in CT to reduce exposure dose. For materials and methods, silicon was used to produce samples. Five spherical samples were produced at 10-millimeter intervals(50, 40, 30, 20, and 10 mm) in diameter and were fixed at 120 Kvp of tube voltage and 50 mA of tube current. Varied slab thickness((1.0, 2.0, 3.0, 5.0, and 7.0mm) and Helical Pitch(1.5, 2.0, 3.0) were scanned. The image at an interval of 1.0, 2.0, 3.0, 5.0, and 7.0mm was transmitted to the workstation. Threshold(-200, -50, 50 ~ 1,000) was changed using the volume rendering technique, 3D image was reconstructed, and artifact volume was measured. In conclusion, 1.5 of Helical Pitch showed the least change of volume and 3.0 of helical pitch showed the greatest reduction of volume change. The experiment suggested that as slice thickness was increased, artifact volume was decreased more than actual measurement. Furthermore, in the 3D image reconstruction, when the range of threshold was set as -200 ~1,000, artifact volume was changed the least. Based on the results, it is expected to have an effect of reducing exposure dose.

• Molecules and Cells
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• v.43 no.1
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• pp.66-75
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• 2020

Saturated fatty acids contribute to β-cell dysfunction in the onset of type 2 diabetes mellitus. Cellular responses to lipotoxicity include oxidative stress, endoplasmic reticulum (ER) stress, and blockage of autophagy. Palmitate induces ER Ca²⁺ depletion followed by notable store-operated Ca²⁺ entry. Subsequent elevation of cytosolic Ca²⁺ can activate undesirable signaling pathways culminating in cell death. Mitochondrial Ca²⁺ uniporter (MCU) is the major route for Ca²⁺ uptake into the matrix and couples metabolism with insulin secretion. However, it has been unclear whether mitochondrial Ca²⁺ uptake plays a protective role or contributes to lipotoxicity. Here, we observed palmitate upregulated MCU protein expression in a mouse clonal β-cell, MIN6, under normal glucose, but not high glucose medium. Palmitate elevated baseline cytosolic Ca²⁺ concentration ([Ca²⁺]_i) and reduced depolarization-triggered Ca²⁺ influx likely due to the inactivation of voltage-gated Ca²⁺ channels (VGCCs). Targeted reduction of MCU expression using RNA interference abolished mitochondrial superoxide production but exacerbated palmitate-induced [Ca²⁺]_i overload. Consequently, MCU knockdown aggravated blockage of autophagic degradation. In contrast, co-treatment with verapamil, a VGCC inhibitor, prevented palmitate-induced basal [Ca²⁺]_i elevation and defective [Ca²⁺]_i transients. Extracellular Ca²⁺ chelation as well as VGCC inhibitors effectively rescued autophagy defects and cytotoxicity. These observations suggest enhanced mitochondrial Ca²⁺ uptake via MCU upregulation is a mechanism by which pancreatic β-cells are able to alleviate cytosolic Ca²⁺ overload and its detrimental consequences.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.4
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• pp.305-312
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• 2007

Among many types of light rail transits (LRT), the rubber-tired automated guide-way transit (AGT) is prevalent in many countries due to its advantages such as good acceleration/deceleration performance, high climb capacity, and reduction of noise and vibration. However, AGT is generally powered by high-voltage electric power feeding system and it may cause electromagnetic interference (EMI) to measurement sensors. The fiber optic sensor system is free from EMI and has been successfully applied in many applications of civil engineering. Especially, fiber Bragg grating (FBG) sensors are the most widely used because of their excellent multiplexing capabilities. This paper investigates a prestressed concrete girder bridge in the Korean AGT test track using FBG based sensors to monitor the dynamic response at various vehicle speeds. The serviceability requirements provided in the specification are also compared against the measured results. The results show that the measured data from FBG based sensors are free from EMI though electric sensors are not, especially in the case of electric strain gauge. It is expected that the FBG sensing system can be effectively applied to the LRT railway bridges that suffered from EMI.

• Journal of the Korean Chemical Society
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• v.36 no.4
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• pp.552-557
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• 1992

Chloramphenicol was studied by differential pulse polarography (DDP). A reduction peak which is dependent on pH of the solution appeared in the voltage range between zero and -1.50 volt vs. Ag/AgCl (sat. KCl) reference electrode. A plot of peak potentials (Ep) measured at room temperature (20$^{\circ}C$) vs. pH of the chloramphenicol solutions showed linear relationship changing slope (Ep/pH) at pH 8.9. The slope was -59.7 mV/pH in pH 2.7∼8.9 and -24.3 mV/pH in pH 8.9∼11.2, respectively. A log plot of peak currents (ip) vs. concentrations showed a linearity at the concentrations between 4.8 ${\times}$ 10$^{-7}$ M and 6.2 ${\times}$ 10$^{-5}$ M (0.16 ppm∼20 ppm) chloramphenicol in pH 8.0 ammonium buffer. Between the DPP method and the reference method measuring absorbance at 278 nm, the correlation coefficient was 0.996, which means an excellent linearity. The DPP method was able to detect degradation products of chloramphenicol in mild alkaline solution (pH = 8.0) more distinctly than the spectrophotometric method.

• Proceedings of the Ginseng society Conference
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• 2002.10a
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• pp.392-400
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• 2002

We have previously found that the saponins but not other components in the ginseng reduce the secretion of catecholamines (CAs) from bovine adrenal chromaffin cells, a model of sympathetic nerves, evoked by acetylcholine (ACh) due to the blockade of $Na^+$ influx through nicotinic ACh receptor-operated cation channels, and it has been concluded that the inhibitory effect may be associated with the anti-stress action of ginseng. However, the saponins, which showed the great reduction of the CA secretion, were mainly the protopanaxiatriols. The protopanaxadiol and oleanolic acid saponins had a little or little such effect. Recent studies demonstrated that the oligosaccharides connected to the hydroxyl groups of the aglycones of the saponins are in turn hydrolyzed by gastric acid and enzymes in the intestinal bacteria when the ginseng is orally administrated. In this study, the effects of their major 6 kinds of metabolites on the secretion of CAs were investigated. All metabolites (M1, 2, 3 and 5 derived from the protopanaxadiols, and M4 and 11 from the protopanaxiatriols) reduced the ACh-evoked secretion from the cells. In the metabolites, the M4 inhibition was the most potent ($IC_{50}({\mu}M):M4(9)$ < M2 (18) < M3 (19) < M1l (22) < M5 (36) < MI (38)). Although M4 also reduced the CA secretion induced by high $K^+$, a stimulation activating voltage-sensitive $Ca^{2+}$ channels, the inhibitory effect was much less than that on the ACh-evoked secretion. M4 inhibited the ACh-induced $Na^+$ influx into the cells in a concentration-dependent manner similar to that of the inhibition of the ACh-evoked secretion. When the cells were washed by the incubation buffer after the preincubation of the cells with M4 and then incubated without M4 in the presence of ACh, the M4 inhibition was not completely abolished. On the other hand, its inhibition was maintained even by increasing the external ACh concentration. These results indicate that the saponins are metabolized to the more active substances in the digestive tract and the metabolites attenuate the secretion of CAs from bovine adrenal chromaffin cells stimulated by ACh due to the noncompetitive blockade of the ACh-induced $Na^+$ influx into the cells. These findings may further explain the anti-stress action of ginseng.

• Journal of IKEEE
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• v.22 no.4
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• pp.1025-1030
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• 2018

The proposed modulator is designed by utilizing a conventional structure employing time division technique to realize the 4th order delta-sigma modulator using one op-amp. In order to reduce the influence of KT/C noise, the capacitance in the first and second integrators reused was chosen to be 20pF and capacitance of third and fourth integrators was designed to be 1pF. The stage variable technique in the low power reconfigurable op-amp was used to solve the stability issue due to different capacitance loads for the reduction of KT/C noise. This technique enabled the proposed modulator to reduce the power consumption of 15% with respect to the conventional one. The proposed modulator was fabricated with 0.18um CMOS N-well 1 poly 6 metal process and consumes 305uW at supply voltage of 1.8V. The measurement results demonstrated that SNDR, ENOB, DR, FoM(Walden), and FoM(Schreier) were 66.3 dB, 10.6 bits, 83 dB, 98 pJ/step, and 142.8 dB at the sampling frequency of 256kHz, oversampling ratio of 128, clock frequency of 1.024 MHz, and input frequency of 250 Hz, respectively.

• Journal of Institute of Convergence Technology
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• v.8 no.1
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• pp.33-39
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• 2018

The screen printing method for forming the electrode by applying the existing pressure is difficult to apply to thin wafers, and since expensive Ag paste is used, it is difficult to solve the problem of cost reduction. This can solve both of the problems by forming the front electrode using a plating method applicable to a thin wafer. In this paper, the process conditions of electrode formation are optimized by using LIEP (Light-Induced Electrode Plating). Experiments were conducted by varying the Ni plating bath temperature $40{\sim}70^{\circ}C$, the applied current 5 ~ 15 mA, and the plating process time 5 ~ 20 min. As a result of the experiment, it was confirmed that the optimal condition of the structural characteristics was obtained at the plating bath temperature of $60^{\circ}C$, 15 mA, and the process time of 20 min. The Cu LIEP process conditions, experiments were conducted with Cu plating bath temperature $40{\sim}70^{\circ}C$, applied voltage 5 ~ 15 V, plating process time 2 ~ 15 min. As a result of the experiment, it was confirmed that the optimum conditions were obtained as a result of electrical and structural characteristics at the plating bath temperature of $60^{\circ}C$ and applied current of 15 V and process time of 15 min. In order to form Ni silicide, the firing process time was fixed to 2 min and the temperature was changed to $310^{\circ}C$, $330^{\circ}C$, $350^{\circ}C$, and post contact annealing was performed. As a result, the lowest contact resistance value of $2.76{\Omega}$ was obtained at the firing temperature of $310^{\circ}C$. The contact resistivity of $1.07m{\Omega}cm^2$ can be calculated from the conditionally optimized sample. With the plating method using Ni / Cu, the efficiency of the solar cell can be expected to increase due to the increase of the electric conductivity and the decrease of the resistance component in the production of the solar cell, and the application to the thin wafer can be expected.