• Plant Journal
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• v.9 no.4
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• pp.26-30
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• 2013

Based on case that HRSG low pressure steam generator tube was damaged by FAC in 500 MW A CCPP. This case analyzed the effect of application about the block of hydrazine water treatment which is applied for increasing dissolved oxygen. And also try to deduce the major factor of FAC Which is caused by lacking of dissolved oxygen of boiler feed system. After 1 year of water treatment, the figure of dissolved oxygen in the boiler feed water has increased from 0.15 ppb to 3~5 ppb and the figure of oxidation reduction potential has increased from -245 mV to 170 mV. And Iron content, the corrosion products by FAC has decreased from 18.5 ppb to 5~7 ppb. According to the result of experiment, we could able to confirm that the interception of hydrazine of water treatment is effective to reduce FAC.

• Journal of Korean Society on Water Environment
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• v.36 no.3
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• pp.185-193
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• 2020

Bimodal flocculation describes the aggregation and breakage processes of the flocculi (or primary particles) and the flocs in the water environment. Bimodal flocculation causes bimodal size distribution with the two separate peaks of the flocculi and the flocs. Extracellular polymeric substances and ionic species common in the water environment increase the occurrence of bimodal flocculation and flocculi-floc size distribution, under the flocculation mechanisms of electrostatic attraction and polymeric bridging. This study investigated bimodal flocculation and flocculi-floc size distribution, with respect to the extracellular polymeric substance concentration and ionic strength in the kaolinite-containing suspension. The batch flocculation tests comprising 0.12 g/L of kaolinite showed that the highest flocculation potential occurred at the lowest xanthan gum (as extracellular polymeric substances) concentration, under all the ionic strengths of 0.001, 0.01, and 0.1 M NaCl. Also, it was important to note that the higher ionic strength resulted in the higher flocculation potential, at all the xanthan gum concentrations. The bimodal flocculation and flocculi-floc size distribution became apparent in the experimental conditions, which had low and intermediate flocculation potential. Besides the polymeric bridging flocculation, steric stabilization increased the flocculi mass fraction against the floc mass fraction, thereby developing the bimodal size distribution.

• Applied Chemistry for Engineering
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• v.16 no.3
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• pp.361-365
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• 2005

Cement-reinforcing carbon fibers were surface-modified with $O_2$, $H_2O$, acrylic acid, diaminocyclohexane plasmas and their effects were investigated. Hydrophobic surfaces with water contact angles of $75{\sim}80^{\circ}$ were changed to hydrophilic surfaces. The water contact angles were reduced down to lower than $10^{\circ}$. As a result, the fiber's hygroscopic property and dispersion in water were improved. Also, Zeta potential of the fiber in water was changed from a negative value to positive values. As a result, adhesion with cement that had a negative Zeta potential was improved up to 57~124% through increased electrostatic interaction.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.2
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• pp.241-249
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• 2013

Ethanolamine (ETA) is widely used for alkalinization of water in steam cycles of nuclear power plants with pressurized water reactor. When ETA contained wastewater was released, it could increase COD and T-N. The treatment of the COD and T-N from ETA wastewater was investigated using the GAC as particle electrodes in three-dimensional electrode reactor (TDE). This study evaluated the effectiveness of GAC as particle electrode using different packing ratio at 300 V. The results showed that GAC-TDE could reduce ETA much more efficiently than ZVI-TDE at the mass ratio of GAC to insulator, 1:2. Additionally, The effect of applied electric potential to COD and T-N reduction was investigated. The results showed the high COD, T-N reduction and current efficiency at the low electric potential. Using the GAC-TDE will provide a better ETA reduction with reducing electrical potential dissipation.

• The Korean Journal of Ecology
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• v.20 no.3
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• pp.175-179
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• 1997

To explanin allopatric distribution of Carpinus cordata and C. laxiflora in the field the effect of soil flooding on photosynthesis and water relations was tested with field grown saplings. Under the flooding condition stomatal conductance of C. laxiflora decreased markedly from day two after flooding treatment and remanined low throughout the experiment. In contrast, flooding had no effect on stomatal conductance of C. cordata throughout the exper iment. The rate of photosynthesis of C. laxiflora was significantly suppressed under flooding conditions, whereas that of C. cordata was not affected in the flooded condition. On day seven after flooding treatment xylem pressure potential of C. laxiflora significantly decreased. Flooding, however, did not have any effect on the xylem pressure potential of C. cordata throughout the experiment. From these findings it is concluded that there is a difference in resistance to flooding between C. cordata and C. laxiflora and that one of the the factors responsible for allopatric distribution in the two species is flooding.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.2
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• pp.65-70
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• 2016

Power interruption is a phenomenon that no voltage is displayed over a short time or long time. Most devices will not operate normally when the supply voltage is low or does not exist. However, the device can also be operated with a different power which is ensured by a separate power generation. Recently, power interruption has been reduced gradually by the improvement of electricity quality, its duration also has been very short. Induction motors are widely used for the pumping in the water and sewage facilities and power plant applications. The pump is used as a machine for moving the fluid in the high place from a low location. So pump equipment always have a potential energy. If a momentary interruption occurs, the potential energy of the pump is reversed as that of water turbine and motor is operated as generator. This study is an analysis for the voltage variation, current, torque and power flow by the generating operation of the induction motor before and after the change of momentary interruption.

• Environmental Analysis Health and Toxicology
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• v.21 no.1 s.52
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• pp.1-11
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• 2006

Arsenic is a ubiquitous element found in several forms in environment. Although certain foods, such as marine fish, contain substantial levels of organic arsenic forms, they are relatively low in toxicity compared to inorganic forms. In contrast, arsenic in drinking water is predominantly inorganic and very toxic. Chronic ingestion of arsenic-contaminated drinking water is therefore the major pathway posing potential risk to human health. World populations are exposed to low to moderate levels of arsenic of parts per billion (ppb) to thousands of ppb. When exposed to human, it could metabolize into monomethylarsonous acid ($MMA^{III}$) and dimethylarsinous acid ($DMA^{III}$) which are highly toxic. Lots of stuides have been recently focused how $MMA^{III}\;and\;DMA^{III}$ induce toxic insults in various target tissues. Epidemiological studies revealed that chronic arsenic exposure caused cancer, cardiovascular diseases, and diabetes etc. In this review, the current understanding of arsenic on health effects will be discussed.

• Proceedings of KOSOMES biannual meeting
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• 2005.05a
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• pp.161-165
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• 2005

Recently, it is on the increase interest for Al alloy with new material for ship application to substitute for FRP ship. The reason is thatAl alloy ship has beneficial characteristics such as high sea speed, increase of loadage and easy to recycle compared with FRP ship. In this paper, mechanical and electrochemical properties are investigated by slow strain rate test experiment in various applied potential condition. These results will provide as reference data to design ship by deciding optimum protection potential regard to hydrogen embrittlement and stress corrosion cracking. In general, Al and Al alloys are not corroded with forming film which has the corrosion resistance property in neutral solution. However, it was observed that formation and destruction of passive film by $Cl^-$ ion in sea water environment. At comparison of current density after 1200 sec in potentiostatic experiment, the current density in the potential range of -0.68 $\~$-1.5 V is shown low value. The low current density means protection potential range. Elongation in applied potential of 0 V was high. However, the corrosion protection application in this condition is impossible potential because the toughness is low value by decreasing strength by active dissolution reaction at parallel part of specimen. The film composed with $CaCO_3$ and $Mg(OH)_2$ has a corrosion resistance property. However, the uniform electrodeposition coating at below -1.6 V potential is not formed since the time to form the uniform electrodeposition coating is short. Therefore, it is concluded that mechanical property is poor because effect by hydrogen gas generation is larger than that of electrodeposition coating. It is concluded that the optimum protection potential range from comparison of_maxim urn tensile strength, elongation and time to fracture is -1.3$\~$0.7 V (SSCE).

• Environmental Engineering Research
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• v.18 no.2
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• pp.85-90
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• 2013

This study is an attempt to quantify rainwater utilization and miscellaneous water demand in Tokyo's 23 special wards, the core of the urban area in Tokyo, Japan, in order to elucidate the potential of further rainwater utilization. The rainwater utilization for miscellaneous appropriate water demands, including toilet flushing, air conditioning, and garden irrigation, were calculated for six different types of building: residential house, office, department store, supermarket, restaurant, and accommodation. Miscellaneous water demands in these different types of building were expressed in terms of equivalent rainfall of 767, 1,133, 3,318, 1,887, 16,574, and 2,227 (mm/yr), respectively, compared with 1,528 mm of Tokyo's average annual precipitation. Building types, numbers and its height were considered in this study area using geographic information system data to quantify miscellaneous water demands and the amount of rainwater utilization in each ward. Area precipitation-demand ratio was used to measure rainwater utilization potential for miscellaneous water demands. Office and commercial areas, such as Chiyoda ward, showed rainwater utilization potentials of <0.3, which was relatively low compared to those wards where many residential houses are located. This is attributed to the relatively high miscellaneous water demand. In light of rainwater utilization based on building level, the introduction of rainwater storage mechanisms with a storage depth of 50 mm for six different types of buildings was considered, and calculated as rainfall of 573, 679, 819, 766, 930, and 787 (mm), respectively. Total rainwater utilization using such storage facilities in each building from 23 wards resulted in the retention of 102,760,000 $m^3$ of water for use in miscellaneous applications annually, and this volume corresponded to 26.3% of annual miscellaneous water demand.

• Journal of Forest and Environmental Science
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• v.23 no.1
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• pp.29-33
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• 2007

This study was purposed to elucidate the best optimum sites by ecophysiological response measurements of Kalopanax pictus samplings of plantation. The diurnal changes of the stomatal transpiration, water use efficiency, water potential, and intercellullar $CO_2$ concentration of leaves were measured by the portable IR $CO_2$ analyzer. The results obtained are summarized as follows. 1) The daily stomatal transpiration rate was highest at 10:00 a.m. After 16:00, the stomatal transpiration rate rapidly decreased. 2) The daily water use efficiency was maximum at 8:00 a.m., and then rapidly decreased until midday with decreasing water potential. 3) The daily $C_i/C_a$ ratio rapidly decreased until 9:00 a.m., and then showed a stable value until 16:00, and then rapidly increased. The daily intercellullar $CO_2$ concentration ($C_i/C_a$ ratio) showed the same tendency as water potential changes. Consequently, stomatal transpiration and water use efficiency was increased with high water potential of leaves at am, and then remarkably decreased with low water potential at pm.