• Analytical Science and Technology
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• v.15 no.3
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• pp.214-220
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• 2002

The interfacial accumulation of the chromium-cupferron complex and the catalytic wave of its redox process is characterized by cyclic voltammetry. One cathodic peak is observed in the forward scan at -1.45 V. Scanning in the reverse direction produces a inverted peak at -1.39 V, which is indicative of a catalytic process. The optimal conditions of inverted peak were found to be 1 mM borate buffer solution(pH 9.48) containing $1{\times}10^{-4}M$ cupferron, holding potential of -1.8 V and scan rate of 20 mV/s. Using main peak, a preconcentration time of 1 min results in a detection limit of $3.2{\times}10^{-10}M$.

• Journal of Sensor Science and Technology
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• v.9 no.2
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• pp.106-112
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• 2000

A FET-type reference electrode(REFET) is an effective method to eliminate typical problems with ISFET(ion sensitive field-effect transistor) such as drift, temperature, light-dependence and miniaturization of reference electrode. However, it is difficult to make the highly reliable REFET with excellent long-term stability and reproducibility. In this paper, an ion-blocking membrane was applied to the REFET for the PET-type electrolyte sensors(pH, pNa-ISFET). The fabricated REFET indicated the stable sensitivity (55.4 mV/pH, 53.5 mV/decade) and good linearity in the pH and pNa measurement. In the measurement, ISFET/Pt/REFET configuration showed excellent stability and reproducibility.

• Analytical Science and Technology
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• v.5 no.2
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• pp.177-184
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• 1992

A preparation method and response characteristics of a glucose sensor which consisted of pH-ISFET and glucose oxidase-immobilized membrane were investigated. The pH-ISFET glucose sensor was fabricated by immbilizing bovine serum albumin and glucose oxidase with glutaraldehyde on gate of the pH-ISFET. Effects of pH and concentration of working buffer and enzyme load on the pontentiometric response of the pH-ISFET glucose sensor were examined. Response characteristics for the determination of glucose in synthetic physiological saline solution(pH 7.4) were as follows. That is the concentration range of linear response, slope of linear response(sensitivity), and response time were $1.0{\times}10^{-4}{\sim}6.0{\times}10^{-3}M $, 4.1 mV/decade, and 12~15 min., respectively.

• Journal of Electrical Engineering and Technology
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• v.10 no.6
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• pp.2364-2367
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• 2015

In this study, we fabricated an electrolyte-insulator-metal (EIM) device incorporating a high-k Al₂O₃ sensing membrane using a porous anodic aluminum oxide (AAO) through a two-step anodizing process for pH detection. The structural properties were observed by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction patterns (XRD). Electrochemical measurements taken consisted of capacitance-voltage (C-V), hysteresis voltage and drift rates. The average pore diameter and depth of the AAO membrane with a pore-widening time of 20 min were 123nm and 273.5nm, respectively. At a pore-widening time of 20 min, the EIM device using anodic aluminum oxide exhibited a high sensitivity (56mV/pH), hysteresis voltage (6.2mV) and drift rate (0.25mV/pH).

• Journal of Microbiology and Biotechnology
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• v.4 no.1
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• pp.49-55
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• 1994

A fungal strain capable of producing extracellular cellulase was isolated from farmland. It was identified as Aspergillus niger, and named Aspergillus niger KKS. Production of cellulase and xylanase by the A. niger KKS was studied through a shake-flask culture. The effects of culture conditions such as inoculum size, temperature, pH, and medium composition on the cellulase and xylanase production were examined. The optimum temperature and pH for the enzyme production were $30^{\circ}C$ and pH 7.0, respectively. The optimized medium was composed of 2.0% (w/v) rice straw, 0.5% (w/v) proteose peptone, 0.5% (w/v) $KH_2 PO_4$, 0.05% (w/v) yeast extract, 0.01% (w/v) $CoSO_4 \cdot 7H_2O$, and 0.05% (w/v) $CuSO$_4$\cdot 5H_2O$. When the strain was incubated with the optimized medium, it gave the activities of endoglucanase, $\beta$-glucosidase, $\beta$-xylosidase, xylanase were 3.80, 4.20, 4.00, 80.0 (IU/mL), respectively. Filter paper and cotton activities were 0.68 and 0.045 (IU/mL), respectively. The results of this study show that A. niger KKS is a potential organism with a wide spectrum of enzyme activities, such as those of $\beta$-glucosidase, $\beta$-xylosidase, and xylanase.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.864-871
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• 1992

A preparation method and response characteristics of a urea sensor which consisted of pH-ISFET and urease-immobilized membrane were investigated. The pH-ISFET urea sensor was fabricated by immobilizing BSA and urease with glutaraldehyde on gate of the pH-ISFET. Effects of pH and concentration of working buffer and enzyme load on the pontentiometric response of the pH-ISFET urea sensor were examined. Response characteristics for the determination of urea in synthetic physiological saline solution (pH 7.4) were as follows. That is, the concentration range of linear response, slope of linear response (sensitivity), and response time were 5.0 ${\times}$ $10^{-4}$ ${\sim}$ 5.0 ${\times}$ $10^{-2}$M, 31.6 mV/decade and 4${\sim}$10 min, respectively.

• Food Science and Preservation
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• v.18 no.1
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• pp.72-78
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• 2011

The physiological properties of oak mistletoe slice extracts were investigated. The total polyphenol content of mistletoe extracts was 50.28-109-69 mg%, depending on extraction conditions. The polyphenol content increased as extract concentration rose (25 mL/g>50 mL/g>100 mL/g). The electron-donating ability (EDA) of the 60% (v/v) ethanolic extract was 68.88% at 25 mL/g; this was the highest value of all extracts tested (p<0.05). The SOD-like activities of water, 30%, 60%, and 90% (all v/v) ethanolic extracts were 15.24-30.84% lower than those of 1.0% and 0.1% (both w/v) L-ascorbate solutions. Tyrosinase inhibitory activities of all samples were 3.40-30.92% lower than those of 1.0% and 0.1% (both w/v) L-ascorbate solutions. Nitrite-scavenging abilities measured at pH 1.2 and pH 3.0 were highest when the water, and the 30%, 60% and 90% (all v/v) ethanolic extracts, were tested. The results expand our understanding of the physiological properties of oak mistletoe slice extracts.

• Journal of Plant Biology
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• v.29 no.1
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• pp.53-65
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• 1986

The montane forests of Ulreung Island, Korea, were investigated by the ZM school method. By comparing the montane forests of this island with those of Korean Peninsula and of Japan, a new order, F a g e t a l i a m u l t i n e r v i s, a new alliance, F a l g i o n m u l t i n e r v i s, a new association, H e p a t i c o-F a g e t u m m u l t i n e r v i s and Rhododendron brachycarpum-Pinus parviflora community were recognized. The H e p a t i c o - F a g e t u m m u l t i n e r v i s was further subdivided into four subassociations; Subass. of Sasa kurilensis, Subass. of Rumohra standishii, Subass. of Rhododendron brachycarpum and Subass. of typicum. Each community was described in terms of floristic, structural and environmental features.

• Korean Journal of Animal Reproduction
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• v.23 no.4
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• pp.281-291
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• 1999

The objective of this study was to optimize the freezing/thawing method of in vitro produced Hanwoo blastocysts. Day 7 blastocysts after IVF were vitrified using EFS40 (40% ethylene glycol, 18% ficoll, 0.3 M sucrose and 10% FBS added m-DPBS) as a freezing solution and electron microscope (EM) grid (V-G) or straw (V-S) as an embryo container. In both method, freezing/thawing were treated by 2-step, treatment time was required in V-G method and V-S method, for 2 min / 3 min and 3.5 min / 10 min, respectively. Embryo survival was assessed as re-expanded and hatched rates at 24 h and 48 h after warming, respectively. The results obtained in these experiments were summarized as follows: when the effect of exposure in vitrification solution and chilling injury from freezing procedure on in vitro produced expanded blastocysts were examined, at 24 h after warming, embryo survival in exposure group (100.0%) was not different compared to that in control group (100.0%), although those results were significantly different with two vitrified groups (V-G: 87.8, V-S: 77.8%) (P＜0.001). However, at 48 h after warming, hatched rates of V-G group (67.8%) were significantly higher than those of V-S group (53.3%) (P＜0.05). In addition, this hatched rate in V-G group was not different with that in exposure group (73.3%). When the effects of embryo developmental stage (early, expanded and early hatching blastocysts) and embryo container (EM grid and straw) to the in vitro survival of vitrified-warmed day 7 Hanwoo blastocysts were simultaneously examined, fast developed embryos were indicated the better resistance to freezing than delayed developed one, irrespective of embryo containers (early; 57.1 ＆ 24.4%, expanded; 84.7 ＆ 60.6%, early hatching; 91.7 ＆ 80.0%) (P＜0.001). Especially, in expanded and early hatching blastocysts, embryo survival of V-G group (67.8, 95.0%) was significantly higher than those of V-S group (53.0, 65.0%) at 48 h post warming, respectively (P＜0.05, P＜0.001). Therefore, this study indicates that Hanwoo blastocysts can be cryopreserved more simple, efficient and successful by vitrification method using EM grid.

• The Korean Journal of Mycology
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• v.19 no.1
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• pp.61-65
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• 1991

For the production of mycelia of mushroom by submerged culture, the experiment was carried out. mushroom. The optimum culture broth for Ganoderma lucidum NG-L were compo­sed of CMC 0.8%(w/v) and $(NH_4)_2SO_4$ 0.2%, with 10%(v/v) of inoculum size and pH 5.5 when the milk whey was used as basal medium. In case of Grifola frondosa ATCC48688, the optimum broth were composed of soluble starch 2%(w/v) and $KNO_3$ 0.l%(w/v), with 8%(v/v) of inoculum size and pH 5.2. Among several plant growth hormones,indole-3-acetic acid and gibberellin $A_3-3-acetate$ stimulated the mycelial growth of Ganoderma lucidum NG-L and Grifola frondosa ATCC 48688 respectively. The culture broth of these mushrooms inhibited the growth of B. subtilis and P. aeruginosa.