• Advances in materials Research
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• v.2 no.2
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• pp.119-131
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• 2013

Impedance and electrical conduction studies of $Ba(Nd_{1/2}Nb_{1/2})O_3$ ceramic prepared using conventional high temperature solid-state reaction technique are presented. The crystal symmetry, space group and unit cell dimensions were estimated using Rietveld analysis. X-ray diffraction analysis indicated the formation of a single-phase cubic structure with space group $Pm\bar{3}m$. Energy dispersive X-ray analysis and scanning electron microscopy studies were carried to study the quality and purity of compound. The circuit model fittings were carried out using the impedance data to find the correlation between the response of real system and idealized model electrical circuit. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type and negative temperature coefficient of resistance character. The correlated barrier hopping model was employed to successfully explain the mechanism of charge transport in $Ba(Nd_{1/2}Nb_{1/2})O_3$. The ac conductivity data were used to evaluate the density of states at Fermi level, minimum hopping length and apparent activation energy.

• Journal of the Korean Electrochemical Society
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• v.10 no.2
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• pp.145-149
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• 2007

Electrochemical studies were performed for a single particle of nickel hydroxide for the cathode of Ni-MH batteries. A carbon fiber microelectrode was manipulated to make electrical contact with an alloy particle, and electrochemical experiments were performed. As a result of cyclic voltammetry, the oxidation/reduction and oxygen evolution reaction (OER) are clearly separated for a single particle. The total cathodic charge (Qred) is practically constant for the scan rate investigated, indicating that the whole particle has reacted. The total anodic charge(Qox) was larger than that of reduction reaction, and the magnitude of oxygen evolution taking place as a side reaction was enhanced at lower scan rates. As a result of galvanostatic charge and discharge measurement, the discharge capacity of single particle was found to be 250 mAh/g, value being very close to the theoretical capacity (289 mAh/g). The apparent proton diffusion coefficient(Dapp) using potential step method inside the nickel hydroxide was found to range within $3{\sim}4{\times}10^{-9}\;cm^2/s$.

• Applied Biological Chemistry
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• v.30 no.1
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• pp.1-8
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• 1987

The distribution of the surface charges in two kinds of peats and their physico-chemical properties have a been studied by means of the potentiometric titration and by ion adsorption in different strength of electrolytes. The organic matter contents were 43.3% and 53.7% in Yeong Yang peat and Peong Tack peat, respectively. Their X-ray diffractograms showed that quartz was dominant in both peats, and illite, kaolinite, hydrated-halloysite and feldspars were contained in a trace. Total acidic group contents was 1.257me/g in Poeng Tack peat that was a little more than of Peong Yang heat were pKa values of Yeong Yang and Poeng Tack peat were 13.1 and 12.65, respectively. The titration curves at different ionic strength of electrolytes crossed at pH 3.9 and 4.4 in Yeong Yang peat, and pH 3.8 and 4.0 in Peong Tack peat. The pH ranges of suspensions when the net surfacecharge of the peats varied from positive to negative value were $pH\;4.55{\sim}5.20\;(NaCl)$ and $pH\;3.95{\sim}5.70\;(CaCl_2)$ in Yeong Fang peat, and $pH\;4.15{\sim}5.40\;(NaCl)$ and $pH\;3.80{\sim}4.15\;(CaCl_2)$ in Peong Tack peat. Therefore it is apparent that the zero point of charge of these peats was about pH 4.0.

• Journal of Fisheries and Marine Sciences Education
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• v.29 no.3
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• pp.920-931
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• 2017

Since the export of Korean-type APR 1400 in 2009 to the UAE, Korea has been achieved management performance, quality inspections, training, nuclear fuel exports for the nuclear power plant. Despite this apparent growth, there are lacking of the research on the marine transportation of radioactive waste. And the terrible accident at the Japan nuclear power plant in 2011 has caused another reconsideration such as emergency response training and plan, reinforcement of safety regulation. According to the Korean government aims to rebuild the appropriate regulation, training, education that is necessary in order to ensure the safety of marine transportation of radioactive waste. Therefore, this study analyzed the various problems identified by the team of experts for the radioactive waste and marine field, the investigation of relevant legal basis, the need for emergency response training for the person in charge of radioactive waste and suggested the simulation-based interactive curriculum during the process of safety verification related to the marine transport of mid- and low-level radioactive waste generated at the Yeon-ggwang nuclear power(Hanbit) plant in 2015.

• Journal of the Korean Chemical Society
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• v.18 no.6
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• pp.400-407
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• 1974

Steady-state anodic and cathodic polarization curves were developed for the Al electrode in 60 mole %$AlCl_3$-40 mole % NaCl at $180^{\circ}C$$453^{\circ}K$). Ohmic resistance contributed substantially to the anodic polarization at current densities greater than 50 mA/$CM^2$ even with capillary tip placed close to the electrode. This could not be rationalized from the resistivity of the melt, which would lead to a much smaller polarization. It was therefore concluded that a layer of high resistance $AlCl_3$ (or $AlCl_3$-rich melt) formed close to the anode surface. From the IR-corrected anodic Tafel and Allen-Hickling plots an apparent anodic charge-transfer coefficient of ${\alpha}_a$ = (2.3 RT/F)(d log i/d${\eta}$) = $1.5{\pm}0.25$ was obtained. At cathodic current densities greater than approximately 30 mA/$cm^2$, slow ion diffusion and dendrite growth both interfered with the measurement of kinetic parameters.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.12
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• pp.831-836
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• 2015

This paper dealt with the PD (partial discharge) characteristics produced by metallic particles presented in a gas insulated switchgear. Four types of metallic particles such as a ball, a trapezoid, a rectangle, and a twist were fabricated and placed in a PD cell filled with $SF_6$ gas. PD pulses were detected through a $50{\Omega}$ non-inductive resistor. Calibration was carried out according to IEC 60270 and the sensitivity was calculated as 4 mV/pC. Apparent charge, pulse count, DIV (discharge inception voltage), DEV (discharge extinction voltage), and TRPD (time resolved partial discharge) were analyzed. Among the metallic particle types, the twist frequently occurred PD pulse at the lowest DIV, while the rectangle showed the highest. DEV of the twist was about 2 times lower than that for the rectangle. Kurtosis of ball clustered at high value, and skewness of other three metallic particles distributed at low value. TRPD showed different distribution by metallic particle types.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.4
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• pp.429-439
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• 1999

Potentiometric titration data were collected for some humic acids purified from Korean upland and paddy soils over a range of pH (3.0 - 11.0) with $NaNO_3$ background electrolyte concentrations (0.01, 0.10, 0.50 and 1.00 M). The data were applied to model A and V which included both intrinsic heterogeneity of humic materials and electrostatic interaction influences on binding sites. The elemental analysis were conducted for various type of humic samples. The $E_4/E_6$ ratio proposed negative correlation with the total carboxyl groups ($r^2$= 0.9988). The charge ($cmol_c\;kg^{-1}$) on the humic acids became more negative as the ionic strength increased. In both continuous and batch titrations, the ionic strength effect was greater in Namweon series (pH 6.39) than others at pH 5.00. The effect of ionic strength on surface charge appears to be greater in batch titrations. This could suggest that continuous titrations do not represent an equilibrium state and the effects of electrolyte concentration was not fully realized during the course of titrations. Both models described experimental data obtained from continuous and batch titrations well over a range of ionic strengths. Model A is more simpler than model V but adaptes more fitted parameters. Thus, the observed change in apparent binding constants with surface charge is regarded solely due to electrostatic influences rather than functional group heterogeneity. However, Model V is more mechanistically realistic in a number of discrete ligand binding sites.

• Journal of Environmental Policy
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• v.14 no.2
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• pp.49-72
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• 2015

Forests in the upstream contributed to improve the quality of water resources for the residents downstream. However, upon structural examination of how the Han River Watershed Management Fund was spent, it became apparent that the fund was not spent toward forest management in the upstream. An additional budget must be allocated if the Watershed Management Committee is to contribute to the management of the upstream forests with such awareness. Therefore, the aim of the study was to assess the willingness to pay and to calculate of budget for forest management in the upstream for water quality improvement. Three hundred surveys on watershed beneficiaries were conducted using biased sampling method. The result was analyzed with conditional logit model and mixed logit model. Forest management, a target variable, was found to have statistical significance. Based on this result, the size of the expected budget was estimated to be minimum 20,526 million won to maximum 20,928 million won.

• The Journal of Fisheries Business Administration
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• v.29 no.2
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• pp.77-96
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• 1998

Fisheries products in Korea generally go through three markets, namely the wholesale market at production site (Market A), the wholesale market at consumption site (Market B), and the retail market (Market C), from producers to end consumers. As the products move from Market A through Market B to Market C, the marginal gap of prices asked in these markets demonstrates an apparent relationship. The producers, middlemen, consumers, and governmental departments concerned may influence the marketing prices of fisheries products. This study employing the cointegration theory tries to investigate whether causality of the price-setting among these markets exists and, if any, what it is. The authors have focused their attention on fisheries markets in Pusan, analyzing the long-run equilibrium relationship and causality between the prices of hairtail and squid among markets at different levels. Data used in this study cover the period f개m August 1984 to December 1997 fer hairtail, and the period from May 1989 to December 1997 for squid. The main findings of the study may be summarized as follows: First, regardless of the price time-series of hairtail and squid in individual market, the first difference is necessary fur satisfying the stationary conditions since each time-series is a first integration. This means homogeneous integration of time-series, which is a requirement of the long-run equilibrium of prices at different markets, is satisfied. Second, the study of the long-run equilibrium relationship between the prices at Market A and Market B shows that a long-run equilibrium relationship does exist for selling prices of the two species at Market A and Market B. Third, the ECM (error correction model ) used here to describe the long- and short-run dynamics of price change demonstrates that, in the case of squid, the price change in Market A will lead to a corresponding price change in Market B in the long-run period. In the short-run, however, the price at Market H is not only influenced by the price change in Market A but influence the price at Market A as well, that is, the Prices between Market A and Market B have a feedback effect. It should be stressed that the limitation in data collection, which cover only two species of hairtail and squid, is likely to cause a sampling bias. Nonetheless, we may conclude that a dynamic relation in the formation of prices does exist in view of the transaction amount of species at different markets. It is believed that the conclusion drawn from this study would not only contribute to a long-lasted debate on the direction of causality of price-setting among academic circle and fishing community, but would provide a useful standard for the policy makers in charge of the price-setting of fisheries products as well.

• The Korean Journal of Physiology
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• v.22 no.2
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• pp.307-318
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• 1988

Properties of succinate transport were examined in basolaterat membrane vesicles (BLMV) isolated from rabbit renal cortex. An inwardly directed $Na^+$ gradient stimulated succinate uptake and led to a transient overshoot. $K^+,{\;}Li^+,{\;}Rb^+$ and choline could not substitute for $Na^+$ in the uptake process. The dependence of the initial uptake rate of succinate on $Na^+$ concentration exhibited sigmoidal kinetics, indicating interaction of more than one $Na^+$ with transporter Hill coefficient for $Na^+$ was calculated to be 2.0. The $Na^+-dependent$ succinate uptake was electrogenic, resulting in the transfer of positive charge across the membrane. The succinate uptake into BLMV showed a pH optimum at external pH $7.5{\sim}8.0$, whereas succinate uptake into brush border membrane vesicles (BBMV) did not depend on external pH. Kinetic analysis showed that a Na-dependent succinate uptake in BLMV occurred via a single transport system, with an apparent Km of $15.5{\pm}0.94{\;}{\mu}M$ and Vmax of $16.22{\pm}0.25{\;}nmole/mg{\;}protein/min$. Succinate uptake was strongly inhibited by $4{\sim}5$ carbon dicarboxylates, whereas monocarboxylates and other organic anions showed a little or no effect. The succinate transport system preferred dicarboxylates in trans-configuration (furmarate) over cis-dicarboxylates (maleate). Succinate uptake was inhibited by the anion transport inhibitors DIDS, SITS and furosemide, and $Na^+-coupled$ transport inhibitor harmaline. These results indicate the existence of a $Na^+-dependent$ succinate transport system in BLMV that may be shared by the other Krebs cycle intemediates. This transport system seems to be very similar to the luminal transport system for dicarboxylates.