• Journal of Biosystems Engineering
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• v.36 no.2
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• pp.96-108
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• 2011

Several methods of in-field measurements of Nitrogen and other soil properties using cores extracted by a hydraulic soil sampler were evaluated. A prototype core scanner was built to accommodate Veris Technologies commercial Vis-NIRS equipment. The testing result for pH, P and Mg were close to RPD (Ratio of Prediction to Deviation = Standard deviation/RMSE) of 2, however the scanner could not achieve the goal of RPD of 2 on some other properties, especially on nitrate nitrogen ($NO_3$) and potassium (K). In situ NIRS/EC probe showed similar results to the core scanner; pH, P and Mg were close to RPD of 2, while $NO_3$ and K were RPD of 1.5 and 1.2, respectively. Correlations between estimations using the probe and the core scanner were strong, with $r^2$ > 0.7 for P, Mg, Total N, Total C and CEC. Preliminary results for mid-IR spectroscopy showed an $r^2$ of 0.068 and an RMSE for nitrate (N) of 18 ppm, even after the removal of calcareous samples and possible N outlier. After removal of calcareous samples on a larger sample set, results improved considerably with an $r^2$ of 0.64 and RMSE of 6 ppm. However, this was only possible after carbonate samples were detected and eliminated, which would not be feasible under in-field measurements. Testing of $NO_3$ and K ion-selective electrodes (ISEs) revealed promising results, with acceptable errors measuring soil solutions containing nitrate and potassium levels that are typical of production agriculture fields.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.72-73
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• 1998

A new method for enzyme immobilization has been developed to remove interference by potential interferents in body fluids. Instead of using electron mediators, we chose direct hydrogen peroxide measurement route. Extremely hydrogen peroxide-selective polymer was coated as an inner membrane to exclude interferents and then glucose oxidase(GOx) was entrapped by electropolymerization of inert monomers. There was no solvent casting step throughout the whole fabrication procedure but all membranes on Pt-Ir electrode were formed by electropolymerization. Thus, membrane thickness, quantity of enzyme loaded and can be controlled by electrochemical parameters. As a result, reproducibility of biosensor characteristics becomes remarkably improved in terms of mass production.

• Analytical Science and Technology
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• v.10 no.3
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• pp.161-167
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• 1997

This is on hydrogen ion-selective memebrane electrodes which were made of tetrabenzylmethylenediamine (TBMDA), tetrabenzylethylenediamine (TBEDA), tetrabenzylpropylenediamine(TBPDA) and tetrabenzylhexylenediamine(TBHDA) as neutral carriers. Their response potentials to carbon number between amino groups showed linear selectivities to hydrogen ion in the range of pH 1~pH 9, pH 2~pH 9, pH 3~pH 9 and pH 4~pH 9 and slopes were 48mV/pH, 52mV/pH, 64mV/pH, 59mV/pH respectively. The interferences effect on the cations were measured to alkali metal ions($Li^+$, $Na^+$, $K^+$), alkaline earth metal ions ($Mg^{2+}$, $Ca^{2+}$, $Sr^{2+}$, $Ba^{2+}$), transition metals ions($Cu^{2+}$, $Ni^{2+}$, $Co^{2+}$) and anions($I^-$, $Br^-$, ${NO_3}^-$, $SCN^-$), and selectivity coefficients were measured by separate-solution method. The membrane electrode made of TBMDA among the electrodes showed the best selectivity in acidic solution.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.6
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• pp.513-521
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• 2009

The primary goal of this research was to develop an optimized analytical procedure for soil analysis based on ion-selective microelectrodes for agricultural purposes, which can perform on-site measurement of various ions in soil easily and rapidly. For the simple and rapid on-site diagnosis, an analysis of soil chemicals was performed employing a multicomponent-in-situ-extractant and an evaluation of ionselective microelectrodes were conducted through the regressive correlation method with a standard analytical approach widely employed in this area. Examination of sensor responses between various soil nutrient extractants revealed that 0.01M HCl and 1M LiCl provided the most ideal Nernstian response. However, 1M LiCl deteriorated the selective response for analytes due to high concentration (1M) of lithium cation. Thus, employing either 0.1M HCl as an extractant followed by 10 times dilution, or 0.01M HCl as an extractant without further dilution was chosen as the optimal extractant composition. A study of regressive correlation between results from ion-selective microelectrodes and those from the standard analytical procedure showed that analyses of $K^+$, $Na^+$, $Ca^{2+}$, and $NO_3{^-}$ showed the excellent consistency between two methods. However, the response for $NH_4{^+}$ suffered the severe interference from $K^+$. In addition, the selectivity for $Mg^{2+}$ over $Ca^{2+}$ was not sufficient enough since available ionophores developed so far do not provide such a high selectivity for $Mg^{2+}$. Therefore, as an agricultural on-site diagnostic instrument, the device in development requires further research on $NH_4{^+}$ analysis in the soil sample, development of $Mg^{2+}$-selective ionophore, and more detailed study focused on potassium, one of the most important plant nutrients.

• PNF and Movement
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• v.11 no.2
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• pp.9-19
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• 2013

Purpose : Study on the effects of attention(working memory) for normal adults by applying transcranial Direct Current Stimulation(tDCS). Methods : There are two groups of 10 random people aged between 20 to 30, one is an experimental group(stimulation) and the other is a comparison group(simulate stimulation). For the 1st da y, pre-stimulation test is executed, and for the 2nd day to the 4th day, tDCS is applied stimulated both on the right prefrontal lobe and the left occipital lobe through the electrode. The stimulation lasts for 15 minutes with voltage power of 1mA for each day. The post-stimulation test is executed on the day of 5th. In this paper, a FAIR attention test is used for measuring the attention. Results : As the result of the experiment, there are significant gaps both on the value of P, the ability of selective attention, and the value of C, the consistent ability after the stimulation on right prefrontal and left occipital lobe. And there is no significant gap on the value Q, the quality(Control). However, all the P, Q, and C values are increased according to the average value between the pre-stimulation test and the post-stimulation. Conclusion : Finally, ability of selective attention and self-control, and consistent attention is progressed by applying the tDCS to the normal people.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.393-404
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• 1992

The response properties of continuous automated system using an enzyme reactor for determination of urea were investigated. The enzyme reactor was constructed to packed-bed form which filled with nylon-6 beads (42∼48 mesh), which immobilized urease with glutaraldehyde, in teflon tube (2 mm I.D., 20 cm length). The system was composed of the enzyme reactor, gas dialyzer, and tublar PVC-nonactin membrane ammonium ion-selective electrode as an indicator electrode in serial order. The response characteristics of this system were as follows. That is, the concentration range of linear response, slope of linear response, detection limit, and conversion percentage were $5.5{\times}10^{-6}$∼$2.4{\times}10^{-3}M$, 57.8 mV/decade, $1.5{\times}10^{-6}$, and 80.8%, respectively. The optimum buffer and life time of urease reactor were 0.01M Tris-HCl buffer solution (pH 7.0∼7.8) and 0.01M phosphate buffer solution (pH 6.9∼7.5) and about 150 days, respectively. And the urease reactor had no interferences of the other physiological materials.

• Analytical Science and Technology
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• v.10 no.6
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• pp.427-432
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• 1997

A selective method for the determination of iron(III) ion with a sodium dodecyl sulfate(SDS) modified glassy carbon electrode was proposed. It was based on the electrostatic attraction and complexation of the SDS modifier, $(DS^-)_n-Fe^{3+}$. The determination of iron(III) ion was performed by a differential pulse voltammetry(DPV), and the reduction peak potential of $(DS^-)_n-Fe^{3+}$ was +0.466(${\pm}0.002$)V vs. Ag/AgCl. For the determination of iron(III) ion, a linear calibration curve was obtained within the iron(III) ion concentration range of $0.50{\times}10^{-5}{\sim}10{\times}10^{-5}mol/L$, and the detection limit was $0.14{\times}10^{-5}mol/L$. $Cu^{2+}$, $Ni^{2+}$, $Co^{2+}$, $Pb^{2+}$, $Zn^{2+}$, and $Mn^{2+}$ showed little or no effect on the determination of iron(III) ion, respectively. But, ion such as each $CN^- $ and $SCN^-$ interfered seriously.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.10
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• pp.1372-1376
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• 2011

The content of Ca in milk exceeds the typical saturation level of Ca salts, which is necessary for neonate growth. This calcium is distributed between the casein micelles in the colloidal and aqueous phases. Information on the properties of calcium activity in the aqueous phase is limited compared with that on the properties of bound or sequestrated calcium. The objectives of this study were to evaluate the changes in calcium activity in fresh milk using an ion-selective electrode and to assess the relationship between calcium activity and milk production in hot season. Milk samples collected from 10 cows at the National Agricultural Research Center for Kyushu Okinawa Region in June to October (Min-Max: 7.2-$35.2^{\circ}C$, 24.3-100% RH) were analyzed on total calcium concentrations and calcium activity. We observed that the rectal temperature of the cows increased according to elevation of ambient temperature but that the pH of the collected milk ($6.61{\pm}0.01$ (Mean${\pm}$SEM)) was not significantly influenced by rectal and ambient temperature. Total calcium concentrations and calcium activity in fresh milk decreased in July (Min-Max: 21.1-$33.5^{\circ}C$, 48.9-100.0% RH) compared with the values after August (Min-Max: 18.1-$35.0^{\circ}C$, 26.5-96.2% RH) (p<0.05); however, there was no significant correlation between the two parameters. The ratio of calcium activity to total calcium concentration decreased after August compared with the values in June and July (p<0.05). The calcium activity in fresh milk was positively correlated with milk yield (r = 0.45, p<0.01) and negatively correlated with milk lactose content (r = -0.53, p<0.01). These results suggest that the calcium activity in milk could be affected by ambient temperature and might be associated with milking production in hot season.

• Clinical and Experimental Reproductive Medicine
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• v.24 no.1
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• pp.67-81
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• 1997

To determine the concentration and the physiologic role of metal components in blood plasma and seminal plasma in relation to male infertility, the concentrations of twelve metal components in blood plasma and seminal plasma including Na, Mg, K, Ca, Cr, Mn, Fe, Cu, Zn, Se, Cd and Pb were measured by atomic absorbance spectrophotometery or ion selective electrode analysis. Semen and blood samples were obtained from a total of 110 men including 70 male infertility patients, 20 vasectomized persons and 20 fertility proven volunteers visited to the Male Infertility Clinic of Pusan National University Hospital. The concentrations of Ca, Zn, Mg, Cr and Cd in control group were higher in seminal plasma than in blood plasma, and additionally Pb were higher in infertility group. The concentrations of all metal components revealed no significant difference according to patients' age, resident, occupation, sperm density, motility and hormone level in blood plasma, but some metal components including Ca, Mg, Cu, Mn, Cd and Pb revealed a significant difference according to each these parameters except patient's age in seminal plasma. The concentrations of Mn, Cd and Pb in the vasectomy persons were higher than in the infertility group III including testicular and epididymal factors, but not in blood plasma. We conclude that the quantitative changes of metal components in the seminal plasma may have effects on not only spermatogenesis and sperm function, but also contribute to diagnostic parameter according to organ specificity of the metal in the male reproduction.

• Korean Journal of Clinical Laboratory Science
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• v.43 no.3
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• pp.105-112
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• 2011

More accurate evaluation of iodine consumption of Koreans can be made by measuring the urinary iodine excretion of people living in representative areas. The data about average iodine excretions by region, sex and age were gathered in order to suggest as a factor the criteria on the progress or prognosis of thyroid disease patients. This study was conducted on 3,000 subjects (2,000 Younggwang-gun residents and 1,000 Muan-gun residents) between July 2004 and August 2005. The data sampling was done based on stratified random sampling and the data were analyzed according to age (the subjects were divided into age groups, five years each) and sex of the subjects. Of the 3,000 subjects, a total of 1,592 people (1,174 in Younggwang-gun and 418 in Muan-gun) participated in this study, which used ISE (iodine ion selective electrode) to measure the concentration of iodine in urine. The 1,592 subjects are composed of 732 males and 860 females. The average urinary iodine excretion was $3.10{\pm}1.75mg/L$ (0.31~15.2 mg/L). The average iodine excretion of males was $3.09{\pm}1.61mg/L$ (0.42~15.2 mg/L) while it was $3.11{\pm}1.86mg/L$ (0.31~12.5 mg/L) among females, which represents no significant difference between males and females. However, the values were significantly higher than those of Europeans and Americans. There were statistically significant differences among the regions. When the data were analyzed according to age, females in their 40s were found to have a little less urinary iodine excretion and males had less and less iodine excretion as they get older. These results are deemed to have a statistically significant difference. This study was conducted on a large number of people (N=1,592) for the first time in Korea. If the data collected through this study can be regarded as the average urinary iodine excretion of Koreans, it is possible to conclude that the average iodine consumptions of Koreans are a lot more than Europeans and Americans. Thus, the effect of much iodine consumption should be studied further.