• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.522-526
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• 2007

Structural features and electrochemical performances of cokes pyrolized from oxidized cokes were examined, and compared with KOH-activated coke. Needle cokes ($d_{002}=3.5{\AA} $), having a graphene layer structure, were changed to a single phase of graphite oxide after oxidation treatment with an acidic solution having an $NaCLO_3$/needle coke composition ratio of above 7.5, and the inter-layer distance of the oxidized coke was expanded to $6.9{\AA} $ with increasing oxygen content. After heating at $200^{\circ}C$, the oxidized coke was pyrolized to the graphene layer structure with inter-layer distance of $3.6{\AA} $. However, the change of the inter-layer distance of the needle coke was not observed in the KOH activation process. On the other hand, an intercalation of electrolyte ions into the pyrolized coke, observed at first charge, occurred at 1.0 V, in which the value was lower than that of KOH-activation coke. The cell capacitor using pyrolized coke exhibited a lower internal resistance of $0.57{\Omega}$ in 1 kHz, and a larger capacitance per weight and volume of 30.3 F/g and 26.9 F/ml at the two-electrode system in the potential range 0~2.5 V than those of the cell capacitor using KOH-activation of coke. This better electrochemical performance may be associated with structure defects in the graphene layer derived from the process of the inter-layer expansion and shrinkage.

• Applied Chemistry for Engineering
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• v.19 no.4
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• pp.407-412
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• 2008

As an activation procedure, in this study, the oxidation treatment of needle cokes with a dilute nitric acid and sodium chlorate $(NaClO_3)$, combined with heat treatment, was attempted. The structures of acid-treated and pyrolyzed coke were examined with XRD, FESEM, elemental analyzer, BET, and Raman spectroscopy. The behavior of double layer capacitance was investigated with the analysis of charge and discharge. The structure of needle coke treated with acid was revealed to a single phase of (001) diffraction peak after 24 h. On the other hand, thecoke oxidized by heat treatment was reduced to a graphite structure of (002) at $300^{\circ}C$. The distorted graphene layer structure, derived from the process of oxidation and reduction of the inter-layer, makes the pores by the electric field activation at the first charge, and generates the double layer capacitance from the second charge. The cell using pyrolyzed coke with 24 h acid treatment and $300^{\circ}C$ heat treatment exhibited the maximum capacitance per weight and volume of 33 F/g and 30 F/mL at the two-electrode system in the potential range of 0~2.5 V.

• Geophysics and Geophysical Exploration
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• v.17 no.4
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• pp.247-252
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• 2014

Gagok Mine, which is skarn deposits, includes sulfide minerals such as sphalerite, galena, chalcopyrite, and pyrrhotite. To explore these minerals, spectral induced polarization (SIP) is relatively effective compared to other geophysical exploration methods because there is a strong IP effect caused by electrode polarization. In the SIP, the chargeability related to sulfide mineral contents and the time constant related to the grain size of the minerals are obtained. For this reason, we aim to compare difference in the mineralized characteristics between two orebodies in the Gagok Mine by using the chargeability and the time constant. For this study, we sampled ores from the south of Wolgok orebody and the north of Sungok orebody. In order to recognize the mineralization characteristics, the metal content of the samples was measured by a potable XRF and the SIP data of the samples were acquired by using a laboratory SIP measurement system. As a result, the metals in the samples such as Pb, Zn, Cu, and Fe were detected by the portable XRF measurement. In particular, the Fe and Zn contents were far higher than the other metals. The Fe and the Zn were caused by the sphalerite and the pyrrhotite through microscopy. The Wolgok orebody had higher sulfide mineral contents than the Sungok orebody and the result corresponded with the chargeability result. However, we considered that the Sungok orebody had a larger sulfide mineral grain size than the Wolgok orebody because the time constant of the Sungok orebody was larger.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.11
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• pp.985-993
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• 2014

This paper suggested a new evaluation method for optimal HUD position through a correlation based on between biological signal as and statistical analysis which using (Electroencephalogram, EEG) and ANOVA. This experiment was conducted two kinds of method to evaluate the optimal HUD position. At first, visual stimulus suggested from six different positions(the top and the bottom of the left, the top and the bottom of the center and the top and the bottom of the right on the screen) in laboratory and an object image was shown for 30 seconds in a screen which has $235{\times}197cm2$ size. And second, HUD image was configured from three different positions and an object image was shown for 30 seconds in a screen. EEG, which used ${\alpha}$-wave and ${\beta}$-wave for evaluate an emotional stability, were measured from Fp1, Fp2, F7 and F8 channel based on ten to twenty electrode system. From the result in laboratory, F7 ${\beta}$-wave was shown statistically significant to significance probability of 0.006 and between ${\alpha}$-wave and ${\beta}$-wave were showed a negative correlation(r=-0.190). Also, Both the top of left and the bottom of center were showed lower ${\beta}$-wave than the bottom of right. From the result in railway simulator, Fp1 ${\beta}$-wave was appeared statistically significant as significance probability of 0.033 and it was showed lower ${\beta}$-wave than center. The outcome of this study will be helpful about evaluation of optimal HUD position through correlation between alpha wave and beta wave.

• The Korean Journal of Physiology
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• v.20 no.1
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• pp.1-7
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• 1986

It has been well documented that the peripheral autonomic nervous system plays an important role in exocrine pancreatic secretion. However, the role of the central nervous system in pancreatic function is still obscure even though the central nervous system has been known to control gastrointestinal functions through the autonomic nervous system. Since the reticular formation in the mesencephalone seems to integrate the autonomic function, the present study was undertaken to investigate a possible influence of the reticular formation upon the exocrine pancreatic secretion. Twenty·two albino rats fasted for 24 hours were anesthetized by intraperitoneal injection of urethane in a dose of 1 g/kg, The pancreatic duct was cannulated to collect pancreatic juice and bile juice was diverted to the jejunum. The gastroduodenal junction was ligated to Prevent passage of gastic juice into the duodenum. A pair of electrodes were bilaterally inserted in the reticualr formation of the mesencephalone with aid of a stereotaxic apparatus. When the volume of pancreatic juice secreted for 10 min became constant, the reticular formation was electrically stimulated for 10 min. Parameters of the electical stimulation was 1.3V, 40 Hz and 2 msec. When the pancreatic secretion returned to the level before the electrical stimulation, cervical vagotomy (11 rats) or administration of propranolol (11 rats) in a dose of 0.1 mg/kg through the jugular vein was carried out. Ten minutes after the treatment, the electrical stimulation of the reticular formation was repeated. The brain was fixed by perfusion of 10% formaline solution through the heart, and then placement of the electrode tip was examined histologically. Protein concentration and amylase activity in samples of Pancreatic secretion were measured. The electrical stimulation of the reticular formation significantly increased in volume $({\mu}l/10\;min)$, Protein output $({\mu}g/10\;min)$ and amylase output (U/10 min) in the pancreatic secretion. The stimulatroy effects were not affected by the cervical vagotomy but completely abolished by propranolol. Meantime, it was also observed that both vagotomy and propranolol significantly reduced the pancreatic secretory function. These results indicate that the reticular formation in the mesencephalone may exert a stimulatory effect upon the Pancreatic secretory function not through the vagus nerve but through the sympathetic pathway in anesthetized rats.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.2
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• pp.262-274
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• 1999

Several alternatives for increasing the fluoride concentration in the mouth, such as water fluoridation, ingestion of fluoride supplements, fluoride paste, fluoride mouthrinse, application of fluoride gel are available. There is an impressive body of evidence that the topically deliverd fluorides are clinically effective in inhibiting the progression of dental caries. Recent studies on the cariostatic action of fluoride have indicated the importance of fluoride in the fluid environment of the teeth. The fluoride levels in unstimulated whole saliva can be considered indicative of F in the aqueous phase available for interaction with the tooth surface at a given time. The retention of F in the mouth after topical fluoride treatment is considered to be an important factor in the clinical efficacy of F. The aim of this study was to determine the elevation and clearance of fluoride in whole saliv after the following topical flouride treatments using HMDS-diffusion technique and fluoride ion electrode. The obtained results were as follow: 1. Average salivary fluoride concentration in the unstimulated whole saliva was $0.0152ppm{\pm}0.0091ppm$. Unstimulated salivary flow rate was between 0.34-0.36ml/min and there was no statistically significant difference among the groups(p>0.05). 2. Except for the immediate time after treatment, fluoride levels followed as APF gel>neutral gel>F-rinse>F-paste. There was no statistical difference between the salivary F concentration of F-paste group and that of control group after 2 hours. In case of F-rinse group, after 3 hours the concentration had dropped to baseline value. But there was statistically significant difference among the F concentraion of F gel groups and that of control group(p<0.05). 3. The mean $AUC_{0-120min}$ values were followed as neutral gel>APF gel>F-rinse>F-paste, and the values of the two former groups were significantly higher than those of the two latter groups(p<0.05).

• Progress in Medical Physics
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• v.14 no.4
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• pp.211-217
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• 2003

The Principal component analysis (PCA) is a well-known data analysis method that is useful in linear feature extraction and data compression. The PCA is a linear transformation that applies an orthogonal rotation to the original data, so as to maximize the retained variance. PCA is a classical technique for obtaining an optimal overall mapping of linearly dependent patterns of correlation between variables (e.g. neurons). PCA provides, in the mean-squared error sense, an optimal linear mapping of the signals which are spread across a group of variables. These signals are concentrated into the first few components, while the noise, i.e. variance which is uncorrelated across variables, is sequestered in the remaining components. PCA has been used extensively to resolve temporal patterns in neurophysiological recordings. Because the retinal signal is stochastic process, PCA can be used to identify the retinal spikes. With excised rabbit eye, retina was isolated. A piece of retina was attached with the ganglion cell side to the surface of the microelectrode array (MEA). The MEA consisted of glass plate with 60 substrate integrated and insulated golden connection lanes terminating in an 8${\times}$8 array (spacing 200 $\mu$m, electrode diameter 30 $\mu$m) in the center of the plate. The MEA 60 system was used for the recording of retinal ganglion cell activity. The action potentials of each channel were sorted by off­line analysis tool. Spikes were detected with a threshold criterion and sorted according to their principal component composition. The first (PC1) and second principal component values (PC2) were calculated using all the waveforms of the each channel and all n time points in the waveform, where several clusters could be separated clearly in two dimension. We verified that PCA-based waveform detection was effective as an initial approach for spike sorting method.

• Journal of Veterinary Clinics
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• v.19 no.2
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• pp.174-185
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• 2002

We investigated the effects of yohimbine and atipamezole in dogs anesthetized with xylazine-ketamine combination on electroencephalography (EEG) . Experiment groups were divided into three according to antagonists . Saline (1 ml) was used as an antagonist in group C, yohimbine (0.1 mg/kg) in group Y and atipamezole (50 ug/kg) in group A. Each group consisted of 5 dogs. Glycopyrrolate was injected 15 minutes prior to xylazine injection. Xylazine (1.1 mg/kg, IM) and ketamime (10 mg/kg, IV) were injected with the interval of 10 minutes. After 15 minutes, antagonists were administered intravenously. For EEG measurements, a recording electrode was positioned at Cz, which was applied to International 10-20 system. Heart rates, body temperature, respiratory rates, arterial blood pressure, $PaO_2$$PaCO_2$$PaCO_2$ at S4 in group Y was significantly decreased(p<0.05). Changes of electrolytes were not significant, except value of $Cl^-$ at S3 in group A. Mean head-up time (the time dogs showing head-up movement after antagonist injection, minutes) was $38.23^{\circ}$ae6.46 in group C, 2.54 $\pm$ 0.93 in group Y and 2.12$\pm$ 1.32 in group A. Mean sternal recumbent time (the time dogs showing sternal recumbency after antagonist injection, minutes) was 45.93$\pm$ 10.27 in group C, 11.91 $\pm$ 7.19 in group Y and 9.88$\pm$ 3.38 in group A. Mean walking time (minutes) was 53.49$\pm$ 9.21 in group C, 22.10$\pm$ 11.10 in group Y and 18.48$\pm$ 4.39 in group A. In group Y all dogs showed excitation and muscle rigidity in emergence. In group A, two dogs were also showed excitation and muscle rigidity, but were weaker than those of group Y.