• Applied Biological Chemistry
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• v.46 no.4
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• pp.380-384
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• 2003

Optimal extraction, separation and capillary rinsing conditions for capillary electrophoresis (CE) were established to discriminate the geographical origin of ligusticum root (Ligusticum wallichii) using 113 samples (domestic sample n = 62, foreign sample n = 51). Ligusticum root was extracted with 30% ethanol and separated on a uncoated fused-silica $(50\;{\mu}m{\times}27\;cm)$ capillary. Conditions for optimal analysis include: temperature, $40^{\circ}C$; voltage, 10 kV; and pressure injection time, domestic and foreign samples were 5 sec and 2 sec, respectively. The optimal separation buffer was 0.1 M phosphate buffer (pH 2.5) containing 15 mM iminodiacetic acid with 40% methanol. Under the optimal conditions established for CE, the ratio of specific peak area (peak LW-1) to other peak area (peak LW-5) was effective in discrimination geographical origin of ligusticum root. The mean accuracy for correct discrimination of geographical origin of domestic and foreign ligusticum roots were 65% and 63%, respectively.

• KSBB Journal
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• v.17 no.4
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• pp.339-344
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• 2002

Flow injection analysis technique for monitoring of xylitol concentrations in biological processes has been developed using xylitol oxidase (XYO) immobilized on VA-Epoxy Biosynth carrier. The immobilized XYO cartridge has been integrated into a FIA system with an oxygen electrode and systematically investigated with regards to the factors which can affect the activity of the immobilized XYO, such as pH, temperature, salt concentration etc. The activity of the immobilized XYO increased with the temperature ($19.0 - 29.0^{circ}C$) and sample injection volume ($75-250\muL$) and molarity of potassium phosphate buffer (0.1-1 M), but it reached the highest value at pH 8.5. The XYO-FIA system has been also applied for on-line monitoring of xylitol concentrations in a reactor and showed good operational stability and agreement with off-line data measured with HPLC.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.555-558
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• 2004

The efficiency of electron injection from the cathode is strongly dependent on the thickness of the LiF buffer-layer. We used LiF to electron Injection layer. We compared characteristics of organic light emitting device changing LiF thin film thickness from 1.0 m to 10.0 nm. Experiment result, we found that LiF thickness has the optimized electrical characteristics in 3.0 m. In this paper, we did research about electrical characteristics of organic light emitting device by LiF thickness change using method numerical analysis method. We proved adequate experimental results that compare results of numerical analysis, and come out through an experiment results is validity.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.30-33
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• 2002

In this study, feasibility of using hydrogen peroxide as a chemical oxidant for in-situ treatment by EK-Fenton technology were investigated. Kaolinite, kaolinite/sand mixture and illitic soil spiked by phenol and phenanathrene were used and variation of electrochemical characteristics were examined by EK-Fenton test. For kaolinite that having low buffer capacity, hydrogen peroxide was injected effectively from anode reservoir. However illitic soil that having relatively higher buffer capacity had low hydrogen peroxide introducing efficiency. The test results showed that Hydrogen ions generated by current increased during the treatment decreased under pH 3 in the most of kaolinite specimen. Therefore, stabilized hydrogen oxide was injected more effectively in the kaolinite specimen. This study suggests that efficiency of hydrogen peroxide injection by EK-Fenton thechnoloty is dependent of variation of pH in the soil

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.1
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• pp.24-28
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• 2012

In this study, we fabricated an amorphous InGaZnO pseudo-MOS transistor (a-IGZO ${\Psi}$-MOSFET) with a stacked $Si_3N_4/SiO_2$ (NO) gate dielectric and evaluated reliability of the devices with various thicknesses of a $SiO_2$ buffer layer. The roles of a $SiO_2$ buffer layer are improving the interface states and preventing degradation caused by the injection of photo-created holes because of a small valance band offset of amorphous IGZO and $Si_3N_4$. Meanwhile, excellent electrical properties were obtained for a device with 10-nm-thick $SiO_2$ buffer layer of a NO stacked dielectric. The threshold voltage shift of a device, however, was drastically increased because of its thin $SiO_2$ buffer layer which highlighted bias and light-induced hole trapping into the $Si_3N_4$ layer. As a results, the pseudo-MOS transistor with a 20-nm-thick $SiO_2$ buffer layer exhibited improved electrical characteristics and device reliability; field effective mobility(${\mu}_{FE}$) of 12.3 $cm^2/V{\cdot}s$, subthreshold slope (SS) of 148 mV/dec, trap density ($N_t$) of $4.52{\times}1011\;cm^{-2}$, negative bias illumination stress (NBIS) ${\Delta}V_{th}$ of 1.23 V, and negative bias temperature illumination stress (NBTIS) ${\Delta}V_{th}$ of 2.06 V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.277-278
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• 2005

Admittance Spectroscopic analysis was applied to study the effect of LiF buffer layer and to model the equivalent circuit for poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV)-based polymer light emitting diodes (PLEDs) with the LiF cathode buffer layer. The single layer device with ITO/MEH-PPV/Al structure can be modeled as a simple parallel combination of resistor and capacitor. Insertion of a LiF layer at the Al/MEH-PPV interface shifts the highest occupied molecular orbital level and the vacuum level of the MEH-PPV layer as a result the barrier height for electron injection at the Al/MEH-PPV interface is reduced. The admittance spectroscopy measurement of the devices with the LiF cathode buffer layer shows reduction in contact resistance ($R_c$), parallel resistance ($R_p$) and increment in parallel capacitance ($C_p$).

• Journal of Sensor Science and Technology
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• v.10 no.3
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• pp.180-186
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• 2001

Recently, FET type dissolved oxygen sensor was proposed to overcome the disadvantages of the amperometric Clark-type sensor. The inherent problem of the proposed sensor, however, is the flow dependence of the sensor performances since the proposed sensor detects the pH change in close proximity to the working electrode. In this study, we decided the direction which minimize the flow effect in FIA(flow injection analysis) system. And a hydrodynamic buffer layer which can reduce the flow dependence were proposed. The suggested buffer-layers were formed onto sensing area and working electrode with mixed polymer matrix of TEOS(tetraethylorthosilicate) and DEDMS(diethoxydimethylsilane).

• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.295-301
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• 2012

The collagen-liposomes were prepared with hydrogenated phosphatidylcholine and by solvent injection method for maximum protection and stable absorption of collagen into the body. Cholesterol was added to phosphatidylcholine to increase the stability of liposome membrane. The mixture was dissolved in ethanol and propylene glycol and PBS Buffer was used to Stabilize ions. The properties collagen-liposome were analyzed by DLS, SEM and POM.

• Transactions on Electrical and Electronic Materials
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• v.6 no.3
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• pp.101-105
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• 2005

Electroluminescence(EL) and current-voltage(I-V) characteristics of hybrid EL devices containing Pr and Mn co-doped ZnS nanoparticles were investigated in this study. For the insertion of a hole transport layer of poly (N-vinyl carbazole)(PVK), the current level became lower due to the accumulation of electrons at the interface between PVK and nanoparticles. When both PVK and buffer layer $BaF_2$ were simultaneously introduced, the enhanced EL efficiency and improved I-V characteristics were obtained. This results from the additional increase of hole injection owing to the internal field induced by the significant accumulation of electrons at the interface. The presence of buffer layer $BaF_2$ together with PVK makes it possible the charge accumulation enough to induce the sufficient internal field for further hole injection.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.4
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• pp.912-916
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• 1999

The purpose of this study was to investigate the effect of saponin in the shoot of Aralia elata on serum lipid level and glucose in streptozotocin(STZ) induced diabetic rats. Sprague Dawley normal male rats weighing 70$\pm$5g were randomly assigned to normal(control group), crude saponin(S group), and shoot of Aralia elata(D group). Experimental diets have been fed for 6 weeks. STZ induced diabetic rats were classified to diabetic control(DC group) and crude saponin(DS group). Diabetic rats were experimentally induced by intravenous injection of STZ(65mg/kg of body weight) dissolved in citrate buffer(pH 4.5). DS group has been i.p. injected with crude saponin solved in phosphate buffer(pH 7.0, 10mg/100g body weight) and DC group fed for 10 days. Body weight decreased significantly in crude saponin group. Feed intakes and feed efficiency ratio were not significantly different among C, S, and D group. The crude saponin group has indicated the lowest values of serum total cholesterol, glucose, and triglyceride. However, the values of serum glucose and triglyceride were not significant. Insulin levels among the crude saponin group, the shoot powder group, and the control group were not significantly different. When STZ induced diabetic rats have i.p. injection of crude saponin, the crude saponin has reduced the serum glucose but it is not been significant.