• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.1 no.2
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• pp.137-144
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• 1997

Flocculation-spectrophotometry and streaming current detector(SCD) method were investigated and compared in order to determine the optimum dosages of synthetic cationic polymers of different charge density and molecular mass for the removal of humic acid. The optimum dosage for each of the polymers was determined with the dosage at which the lowest absorbance of humic acid was shown for the former and was determined with the dosage required during charge neutralization of humic acid for the latter. It was in good agreement between both methods and there is a strong inverse correlation between the optimum dosage and charge density of the polymers, with highly charged polymer giving the lowest optimum dosage, pointing out the importance the charge neutralization. By flocculation-spectrophotometry, it was found that the absorbance of humic acid with the amount of each of the polymers dosed, changes sharply for polymers of high charge density, but changes rather broadly for polymers of low and middle charge density. Both methods showed that a stoichiometric correlation exists between the optimum dosage of each of the cationic polymers and the negatively charged humic acid.

• Journal of Powder Materials
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• v.13 no.2 s.55
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• pp.112-118
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• 2006

[ $R_{1/3}Sr_{2/3}FeO_{3}$ ](R=Pr, Nd, and Sm) was synthesized and their magnetic properties and charge ordering(CO) transition related with lattice dynamics and oxygen vacancy were systematically investigated. The charge disproportion ation(CD) in $R_{1/3}Sr_{2/3}FeO_{3}$(R=Pr,Nd) was in which two kins of iron with valence state $Fe^{3+}$ and $Fe^{5+}$ were found with ratio of 2:1. In this charge ordering state a sequence of $Fe^{3+}Fe^{3+}Fe^{5+}Fe^{3+}Fe^{3+}Fe^{5+}$ exists aligned along the [111] direction of the pseudocubic perovskite structure. The charge ordering exist in distorted structure involving $t_{pd}$ hybridization. The disordering phases coexist in distorted structure as temprature in creases that is controlled amount of oxygen vacancy. The magnetic hyperfine fields indicate charge tranfering temperature as it dissapeared drastically.

• Transactions on Electrical and Electronic Materials
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• v.11 no.1
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• pp.42-47
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• 2010

Polymer insulating materials such as cross linked polyethylene (XLPE) are employed in electric cables used for extra high voltage. These materials can degrade due to chemical, mechanical and electric stress, possibly caused by voids, the presence of extrinsic materials and protrusions. Therefore, this study measured discharge patterns, discharge phase angle, quantity and occurrence frequency as well as changes in XLPE under different temperatures and applied voltages. To quantitatively analyze the irregular partial discharge patterns measured, the discharge patterns were examined using a statistical program. A three layer sample was fabricated, wherein the upper and lower layers were composed of non-void XLPE, while the middle layer was composed of an air void and copper particles. After heating to room temperature and $50^{\circ}C$ and $80^{\circ}C$ in silicone oil, partial discharge characteristics were studied by increasing the voltage from the inception voltage to the breakdown voltage. Partial discharge statistical analysis showed that when the K-means clustering was carried out at 9 kV to determine the void discharge characteristics, the amount discharged at low temperatures was small but when the temperature was increased to $80^{\circ}C$, the discharge amount increased to be 5.7 times more than that at room temperature because electric charge injection became easier. An analysis of the kurtosis and the skewness confirmed that positive and negative polarity had counterclockwise and clockwise clustering distribution, respectively. When 5 kV was applied to copper particles, the K-means was conducted as the temperature changed from $50^{\circ}C$ to $80^{\circ}C$. The amount of charge at a positive polarity increased 20.3% and the amount of charge at a negative polarity increased 54.9%. The clustering distribution of a positive polarity and negative polarity showed a straight line in the kurtosis and skewness analyses.

• Journal of Korea Port Economic Association
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• v.20 no.2
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• pp.73-87
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• 2004

The purpose of this paper is to setup reasonable criterion for underwriters to reimburse the expenses of suing and labouring incurred by assured, using game theory. As for the upper limit for the reimbursement, MIA and ICC do not mention at all but stipulate that proper and reasonable expenses shall be reimbursed, while ITC-Hulls set the amount insured as the upper limit to compensate the sum of expenses and damage loss. And as for failed measures of averting and minimizing loss, MIA and ICC do not mention either, while ITC-Hulls stipulates underwriters shall compensate the expenses and damage loss within the amount insured. The main results of this paper are as follows: First, it is for the benefit of underwriters to reimburse the expenses incurred to take such reasonable measures to avert or minimizing a loss which would be recoverable under the insurance. Second, the expenses of single measure should not be above the amount insured. Third, even if the measures failed, the expense should be reimbursed if it is less than the expected value of the subject-matter insured that could be recovered by the measures. Last, if the measures are taken several times individually, even if the sum of expenses might be above the amount insured, it should be reimbursed.

• Journal of the Korean Institute of Gas
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• v.4 no.2 s.10
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• pp.33-36
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• 2000

As a result of electrostatic hazard analysis of electrostatic removing wear about combustible gas, in accordance with using period, character of charge voltage is shown that propensity is increased. but character of electrostatic charge amount is below standard(0.6 $\mu$C) of the hazard of electrostatic removing wear, It would seem that character of charge voltage is raised because of swelling phenomenon of the normal fiber and other phenomena. Besides, In some case '96 parka of electrostatic removing wear shown as 0.82$\mu$C that exceed the uppermost limit of the fire and explosion. Therefore, countermeasure or improvement and control are needed.

• Journal of Information Display
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• v.1 no.1
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• pp.42-47
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• 2000

The relationship between driving voltage and the amount of wall charge in the address period of surface discharge type AC Plasma Display Panel has been investigated. The amount of wall charge on each electrode is obtained simultaneously from the current profiles after applying only one addressing discharge pulse. The wall charge $Q_y$ on the scan electrode Y is almost the sum of $Q_x$ on the address electrode X and $Q_z$ on the sustain electrode Z. The $Q_y$ increased with the driving voltage regardless of the kind of electrode, whereas the addressing $T_d$ decreased. The $Q_x$ and $Q_y$ are increased considerably by blocking voltage $V_z$, whereas $Q_x$ is decreased. The $V_z$ dependence of $Q_x$ $Q_y$ and ${\varrho}_z$ in addressing discharge was $-13{\times}10^{-2}$ (pc/$V_z$), and $60{\times}10^{-2}$ ($pc/V_z$) and $70{\times}10^{-2}(pc/V_z)$, respectively.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.2
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• pp.17-22
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• 2003

The priming discharge characteristic at the reset period in the ADS drive method of PDP was experimentally analyzed in this research. The amount of wall charge accumulated by the discharge and the accumulated time are unrelated to the priming pulse width. The self-erase discharge by excessive wall charge is related to the amount of wall charge by the priming discharge and this is related to space charge generated by the priming discharge. From the experimental result, in the optimized priming condition the plus width is 8$mutextrm{s}$ and the voltage is about 163V. The space charge which helps the self-erase discharge exists during about 16$mutextrm{s}$ immediately after generating the priming discharge. Therefore, it is suitable within 16$mutextrm{s}$ of the priming pluse width for the effective reset process.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.9
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• pp.96-102
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• 2015

This paper presents battery charging method using 3-phase AC-DC boost converter. General battery charging method is that charging the battery voltage to the reference voltage according to the constant current(CC) control, when it reaches the reference voltage, charging the battery fully according to the constant voltage(CV) control. However, battery chaging time is increased because of the battery impedance, constant current charging section which shoud take the large amount of charge is narrow, and constant voltage charging section which can generate insufficient charge is widen. To improve this problem, we proposes the method to reduce the charging time according to the SOC(State of Charge) estimation using battery impedance.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.187-192
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• 2001

A homogeneous premixed charge compression ignition engine is experimentally investigated for the reduction of exhaust emissions in diesel engines. In this study, the premixed fuel is injected into the intake manifold to form homogeneous pre-mixture in the combustion chamber and then this pre-mixture is ignited by small amount of diesel fuel directly injected into the cylinder. In the premixed charge compression ignition engine, NOx and smoke concentration of the exhaust emissions were reduced simultaneously as compared with the conventional diesel engine. But HC and CO emissions were increased with the increase of premixed ratio. The combustion characteristics of premixed charged diesel engine such as the power output, the rate of heat release, and the other characteristics are discussed.

• International Commerce and Information Review
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• v.10 no.4
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• pp.513-532
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• 2008

The purpose of this study was to analyze which factors have had impacts on extension export insurance charge of Korean export insurance. In order to attainment of this study, an empirical study was proceeded. The export insurance charge was hired as the dependent variable and export insurance premium, insurance compensation charge, export insurance collection charge and export insurance fund were used as independent variables. Data was used for estimation are the annually data from 1969 to 2007. From results of this analysis, we find the hired variables have highly correlation among them and the most influential factor turns out to be export insurance fund. Main results of this study was as follows : i) The export insurance fund must be increased immediately. ii) It is necessary that Korea Export Insurance Corporation give their attention to the compensate amount of export insurance compensation on specific insurance item. iii) It is necessary that Korea Export Insurance Corporation extension the collection efforts of the export insurance. iv) A reasonable raising of export insurance premium need to be done.