• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.217-220
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• 2007

The purpose of study is a development of the high reliance electric driven water-pump that fuction is forcing the movement of water using basic design, proto sample and test at the cooling system. It was important to supply a coolant quickly and accurately for the requirement of flow rate at the system when we carried out the designs for BLDC Motor, Controller and water pump(Impeller, Volute Casing, Sealing Device) First, we attained ours purpose that the target efficiency for water pump was over 40% and then we are doing the optimum design for Brushless Motor and Controller that its target is over 55% of efficiency.

• 분석과학
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• 제8권4호
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• pp.405-410
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• 1995

A study on elemental speciation of trace metals in lake water (Lake Biwa in Japan) has been carried out by a size exclusion chromatography (SEC) / inductively coupled plasma mass spectrometry (ICP-MS) system. Before analysis, the water sample was preconcentrated with a ultrafiltration technique, where the large molecules with molecular weight larger than 10,000 were concentrated. Then the preconcentrated water samples (500-1000 fold) were analyzed by a SEC/ICP-MS system. Most trace metals were found at the UV absorption peaks corresponding to the molecular weights of ca. 300,000 and 10,000-50,000, where trace metals were on-line detected by ICP-MS. The results suggest that many of trace metals exist as the large organic molecules-metal complexes in natural water.

• Journal of Radiation Protection and Research
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• 제38권4호
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• pp.185-188
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• 2013

Heating method using electric heater was used to reduce water content in fingernail clippings. Authors found that low water content is helpful to measure EPR signal of fingernail sample with enhanced variability. Generally, natural dehydration happens in normal room condition at least one month and needs much time for using in experiment. So, artificial heating method is applied in this study for time savings. Fingernail samples were tested to find effect of water content to the EPR signal on microwave power levels for dosimetry. Low water content in fingernail reduced variability of EPR signal and makes it possible to measure accurate EPR signal. It also made it possible to measure constant movement of EPR signals on several microwave power levels. Although this method was difficult to apply directly in fingernail/EPR dosimetry, we, authors, believe that this heating method would be useful to differentiate MIS2 and RIS which are generally located at the same g-factor and almost impossible to be identified with each other.

• 자원ㆍ환경경제연구
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• 제11권2호
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• pp.321-333
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• 2002

Approximating bottled water consumption distribution is complicated by zero observations in the sample. To deal with the zero observations, a mixture model of bottled water consumption distributions is proposed and applied to allow a point mass at zero. The bottled water consumption distribution is specified as a mixture of two distributions, one with a point mass at zero and the other with full support on the positive half of the real line. The model is empirically verified for household bottled water consumption survey data. The mixture model can easily capture the common bimodality feature of the bottled water consumption distribution. In addition, when covariates were added to the model, it was found that the probability that a household has non-consumption significantly varies with some variables.

• 상하수도학회지
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• 제27권5호
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• pp.611-619
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• 2013

In this study, Back Tracing Calculation Method was developed to determine the leakage location and leakage amount. Previously developed determination method of monitoring location and newly developed Back Tracing Calculation Method were applied to the sample pipe network and real size pilot plant. After leakage was assumed in the pilot plant, leakage location and leakage amount could be traced by Back Tracing Calculation Method. From the results, it was found that Back Tracing Calculation Method can be applied for the leakage detection in water distribution system. Furthermore, this method can be applied for the pressure management or leakage detection as a pressure control method in water distribution system.

• 상하수도학회지
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• 제13권3호
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• pp.56-60
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• 1999

In this study the feasibility of usage of raw sludge (sludge from water treatment plant) and chalk from schools and institutes was investigated to remove the phosphorus in water and wastewater. In this study phosphorus removal efficiencies of sludge and chalk were investigated by changing various factors. The time to reach the equilibrium using chalk and raw sludge under different pHs was obtained. Based on this result, Freudlich adsorption isotherm was applied. Results showed that a portion of phosphorus was removed by adsorption to chalk and raw sludge. The phosphorus removal efficiency using calcinated chalk was about three times higher than that of chalk. It means that some portion of $CaCO_3$ contained in chalk was converted to CaO by calcination and this was proved by X-ray diffraction experiment. About 90% phosphorus removal was observed using sludge and calcinated chalk respectively while about 20% phosphorus removal efficiency was achieved using chalk from the water sample in Lake Sihwa.

• 한국물환경학회지
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• 제22권2호
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• pp.321-327
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• 2006

This interlaboratory study was designed to evaluate protozoan test methods in water and to predict the major causes of deviation of the methods. Each of four laboratories with previous experience of protozoa analysis in water participated, and met the initial performance criteria of EPA 1623 method provided. The protozoan analysis procedure consists of filtrations, concentration, immunomagnetic separation, dyeing (staining) and counting with observation. We tested three different filtration equipments: capsule filter for 10 L of surface water, and high volume (HV) capsule filter and membrane filter for 100 L of finished water. When the recovery of each step of the procedure was evaluated with EasySeed, the commercial stock of each 100 Cryptosporidium and Giardia, immunomagnetic separation and filtration step were the most crucial steps affecting the stability of the recovery, especially for Cryptosporidium. There was no significant difference of recovery among the filtration methods. Recovery of protozoa from source water were evaluated with spiked EasySeed as matrix tests. The recoveries of Giardia increased significantly in the matrix tests compared those in the deionized water. We also applied red stained mixture stocks of Cryptosporidium and Giardia called ColorSeed as internal standards of water sample tests. The recoveries of both EasySeed and ColorSeed in samples tested were within the range of the criteria, however, the Giardia recoveries using ColorSeed decreased significantly. Further optimization study with ColorSeed will be necessary, considering the convenience of using the internal standard without additional sample analysis. The significant factors of the recovery variation were identified as the differences of laboratories as well as water quality and type of the stock for spiking. The results of this study emphasize the importance of the quality assurance program for protozoan analysis lab in water.

• 한국환경보건학회지
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• 제14권1호
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• pp.33-38
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• 1988

Natural mineral water is generally quite different from ordinary drinking water due to its original nature and various properties. The complexity of natural mineral water requires, therefore, not only to identify its nature and proper characteristics, but also to classify them by a reasonable scientific basis of comparison. The study was concentrated on a possible classification technique to natural mineral waters by their constitutions and physico-ehemical properties. The classification was carried out by the computation of such numerical parameters as ionic equivalent percentage, electrolytic conductance or mobility, ionic molecular weight, molecular concentration, equivalent conductivity and degree of ionization in consideration of the determinative criteria as follows -particular single element or molecule -major components of natural waters as bicarbonate, sulphate, chloride,caloride, calcium, magnesium, and sodium -moleculat concentration related to blood osmotic pressure -water temperature at emergence from spring -contents of free carbon dioxide (CO2) -pH value of water -total dissolved solids or salts (NaCl) The results obtained proved out to be clearly distinguhhable from ordinary drinking water as far as concern natural mineral water as an example on the subject -simple water -bicarbonate-predominating water -cold spring -carbonated-non gaseous water -weak alkaline water -non saline water Putting these various results together, the sample turned out to be a kind of natural mineral water that can be used as a drinking water if microbiologically safe.

• 한국해양공학회지
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• 제25권2호
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• pp.85-91
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• 2011

Many protection methods such as surface coating, electric protection, or other methods have been applied to the numerous steel structures widely used in continental and marine areas to control their corrosion, which is done from an economic point of view. Most of these steel structures are primarily protected by coating methods. However, some steel piles under seawater are protected by the electric protection method, that is, either using an impressed current or a sacrificial anode method. Furthermore, environmental contamination may cause a severely corrosive environment, which, in turn, causes the accelerated corrosion of steel structures. Subsequently, coated steel structures could deteriorate more rapidly than the designed lifetime because of the acid rain caused by air pollution, etc. Therefore, a coating of marine paint exposed to seawater, that is, underwater hardening painting, is increasingly required to be fast drying as well as highly corrosion resistant. In this study, five types of underwater hardening paints were prepared with different resin series and additives. Their corrosion and water resistances were investigated using electrochemical methods such as corrosion potential, polarization curves, impedance and cyclic voltammogram measurements, etc. Even though it is generally accepted that the corrosion resistance of bare steel tends to increase with a shift of the corrosion potential in the noble direction, the corrosion resistance of a sample with a coating exhibited a relatively better tendency when it had a lower corrosion potential in this study. The corrosion current density was also decreased with a decrease in the diffusion limiting current density, which may mean that there is some relationship between corrosion and water resistance. The S sample of the ceramic resin series showed the relatively best corrosion and water resistance among those of samples, while the worst corrosion and water resistance were observed for the R sample of the epoxy resin series. The corrosion and water resistance of those samples tended to deteriorate with an increase in the immersion days, and their corrosion and water resistances were considered to be apparently improved by the types of resin and additives.

• Bulletin of the Korean Chemical Society
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• 제27권3호
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• pp.413-418
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• 2006

Sodium hyaluronate (NaHA), water soluble polymer having ultra-high molecular weight, is characterized by using on-line frit inlet asymmetrical flow field-flow fractionation (FI-AFlFFF) and multiangle light scattering (MALS). This study demonstrates the capability of power programming FI-AFlFFF for the separation of NaHA and the applicability of FI-AFlFFF with MALS for the characterization of molecular weight distribution and their structural information. Since sample injection and relaxation in FI-AFlFFF are achieved by using hydrodynamic relaxation, separation of high molecular weight polymers can be achieved smoothly without halting the separation flow. Experiments are carried out with the two different NaHA products (a raw NaHA sample and a thermally degraded NaHA product) and molecular weight distribution and conformations in solution are determined. Influence of sample filtration on the change of molecular weight distribution is also discussed.