• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.3
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• pp.105-113
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• 2007

This study was conducted to analyze the effects of environmental factors such as soil moisture, light intensity, temperature and humidity on changes in cambial electrical resistance. To improve data quality, cambial electrical resistance was continuously measured at fixed points by using a data logger isolated from alternating current. The relationship between environmental factors and changes in cambial electrical resistance was also analyzed. The results are as follows: 1. Cambial electrical resistance is highly correlated to the temperature of the measured area(r=-0.934). Therefore, temperature compensation is needed to analyze the effects of other environmental factors on cambial electrical resistance changes. 2. If temperature is compensated for, the change of cambial electrical resistance is highly correlated to water vapor pressure(r=-0.836). 3. If temperature and humidity are compensated for, the change of cambial electrical resistance is highly correlated to intensity of light(r=-0.738). 4. Diurnal deviation of soil water potential is not more significantly related than the change of cambial electrical resistance. However, in the long-term, soil water potential and cambial electrical resistance are highly correlated(r=-0.831). This indicates that soil moisture significantly influences the long-term change of cambial electrical resistance.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.6
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• pp.709-715
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• 2007

The dewaterability of a sludge can be characterized by two ways: the residual moisture content in the sludge cake after dewatering process, and the filtration of the sludge. Time to filter (TTF) represents filtration processes that are special cases of the flow through a solid matrix concept. TTF characterizes a resistance to filtration. The sludge resistance, in turn, can be subdivided into resistances associated with the solid phase and the liquid phase to evaluate the effect of each of the two phases on sludge dewaterability. In order to determine the dewatering characteristics of the water sludge samples, TTF and zeta potential were measured. For these studies cationic polymer was chosen for water sludge dewatering experiments. The zeta potential of thickener sludges neared from minus values to zero values till 4 days after sampling. The dewaterability of thickener sludges using cationic polymer was deteriorated according to the increase of detention time. As the detention time was increased from 4 to 10 days, the optimal dose of the polymer was increased from 4 to 8mg/L. Therefore, the optimal detention time plays an important part for the dewaterability of a sludge.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.1 s.109
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• pp.1-9
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• 2005

Many factors which affect the adsorption of cationic polymers on fibers and fines have been investigated by many researchers that include contact time, pH, collision frequency, properties of cationic polymers and adsorbent, etc. But the effect of white water quality on the adsorption of cationic polymer have not been examined throughly. In this study, the adsorption of cationic PAM was analyzed as a function of white water quality. The adsorption of the cationic PAM was analyzed by two analysis methods, Kjeldahl nitrogen content measurement and electrokinetic measurements. When the distilled water was used, adsorbed amount of C-PAM and zeta-potential of fibers increased as a function of the addition of C-PAM. When closure level increased, nitrogen content of fibers increased indicating that the cationic PAM was adsorbed. Zeta-potential of fibers, however, showed no significant change with the increased addition of C-PAM. This showed that adsorption of C-PAM was not reflected by zeta-potential of fibers due to the deteriorated efficiency of C-PAM by the anionic contaminants in white water.

• Journal of Environmental Health Sciences
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• v.45 no.6
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• pp.561-568
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• 2019

Objectives: The most commonly detected heavy metals in rocks and soils, including Pb, Cd, Cu, Fe, Mn and As, are representative pollutants discharged from abandoned mines and have been listed as potential sources of contamination in drinking water. This study focused on increasing the removal efficiency of heavy metals from drinking water resources by surface modification of natural adsorbents to reduce potential health risks. Methods: Iron oxide coating and graft polymerization with zeolites and talc was conducted for bipolar surface modification to increase the combining capacity of heavy metals for their removal from water. The removal efficiency of heavy metals was measured before and after the surface modification. Results: The removal efficiency of Pb, Cu, and Cd by surface modified zeolite showed 100, 92, and 61.5%, respectively, increases compared to 64, 64, and 38% for non-modified zeolite. This implies that bipolar surface modified natural adsorbents have a good potential use in heavy metal removal. The more interesting finding is the removal increase for As, which has both cation and anion characteristics showing 27% removal efficiency where as non-modified zeolite showed only 2% removal. Conclusions: Zeolite is one of the most widely used adsorptive materials in water treatment processes and bipolar surface modification of zeolite increases its applicability in the removal of heavy metals, especially As.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.6
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• pp.71-76
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• 2007

This paper describes a risk assessment of electric shock based on a experiment which demonstrates a submerged commercial power source. For the experiment a water tank was made and an outlet was installed on an interior wall. After filling the tank with a conductive water solution, the electric potential was measured with the distance, the direction from the power source, the conductivity and the level of the water solution. As a result, the potential distribution due to the outlet energized and exposed to the water solution depends on the distance from the submerged power source, however, the direction from the power source, the conductivity and the level of the water solution seemed to scarcely affected on the electrical shock risk.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2000.06a
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• pp.34-39
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• 2000

Today's size of production operations in the packaging paper sector I sconstantly increasing , featuring integral processing systems, high-speed paper machines, and the increased marketing of lower basis weight products. The risk factors involved in these large investments lie more than ever in the available furnish potential and ongoing requirements for further closure of water loops and lower operating costs. A comparison is drawn between recovered paper furnish mixtures used in European mills with regard to fibre properties, strength potential and contaminant content, Both the furnish situation and development trends in modern fluting and testliner machines are instigating concept changes in stock preparation, the approach flow as well as in process water and rejects technology. Developments are currently focussed for example on more efficient debris separation using fine slotted screening, optimized refining , more systematic process water management with loop separation and integral water clarification as well as more efficient removal of microstickies, fillers and fines through appropriate combination of rejects handling and water clarification processes. Product quality differentiation depends decisively on strength characteristics as a function of refining , fines removal , paper machine technology, and sizing . Maximum availability of today's high speed paper machines and , as a result, cost effective production can be ensured by optimum balancing of all subsystems with in the overall concept and by reliable control of problems with contaminants and deposits.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.218-218
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• 2019

Jeju island has an area of $1,810km^2$ and is considered the largest island in South Korea. In Jeju Island the average annual precipitation is 1,957mm. About 54% of precipitation is estimated to be lost due to evapo-transpiration and direct runoff, and the remainder is recharged. Historically springs and puddles were the island's primary sources of water. However, after 1970 all sectors, including the urban and industrial sectors depended solely on groundwater as their water resource. As vast amount of water is being recharged the Island has many springs, especially near the coastlines. Historlcally, spring of Jeju Island formed village and make it possible to continue a life. Also it produces many values such as the spring related story, culture, tourism and ecosystems. Especially, the naturally rare phenomenon that about 900 springs appear over the whole area of Jeju Island makes it possible to call it as a natural heritage. As a result of this most springs have either been destroyed or been in the state of neglect. In some cases it has been observed that springs were preserved by nature, however majority of the cases saw springs losing their own nature as a result of abandonment. It was recorded that there were 911 springs in Jeju Island with most of them being distributed along the coast, which consequently increases their susceptibility to seawater intrusion. The objective of this study is therefore to analyze Eco-cultural and Engineering characteristics about springs in the island, highlighting its past utilization and reestablishing its potential as a source of spring.

• Korean Journal of Weed Science
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• v.17 no.3
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• pp.310-313
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• 1997

The seedling of barley and weed would be generally inhibited by rice straw residues in the field. This experiment was carried out to investigate the allelopathic effects of rice straw and environmental conditions of germination such as osmotic potential, pH on the seedling of barley and water foxtail. The pH did not affect the germination of barley and water foxtail. Osmotic potential to -2.9bar, -0.6bar did not affect the germination of barley and water foxtail, respectively. Rice straw mixed with soil at the concentration of 4%(w/w) reduced the dry weight of shoot and root, and volume of barley root, as compared to the untreated control. Dry weight of water foxtail by rice straw mulching was decreased by 87.1%, 86.2%, respectively.

• Journal of Korea Water Resources Association
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• v.40 no.8
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• pp.665-675
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• 2007

An equation is developed to estimate potential groundwater resources available for development. This equation is useful for preliminary planning stages prior to detailed design stages. The equation is a function of major factors such as aquifer characteristics, saltwater intrusion length, coastal groundwater discharge and potential locations of pumping wells. Thus, most important factors are taken into account. The equations are derived using well-known analytical solutions. Thus, the basis is scientifically sound. Use of the equation is quite simple since it is an explicit function of variables. A logical method is proposed to assess a radius of influence of a pumping well considering aquifer characteristics and the pumping rate. Applications to a hypothetical problem and comparison with results from a more rigorous numerical simulation model indicate that results obtained from the proposed equation are conservative.

• Journal of Environmental Science International
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• v.4 no.2
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• pp.121-139
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• 1995

Based on the Results of Marine Meteorological and Oceanographical Observations (1966 -1987), the phenomenon of chimney is found as a candidate for the formation of the Japan Sea Proper Water (JSPW). The chimney phenomenon occurs twelve times Inuring 1966∼ 1987. The water types in the chimney denoting the deep convection are similar to those of the JSPW 0∼ 1℃ in potential temperature, 34.0∼34.1 ‰ in salinity and 68∼80 cl/t in potential thermosteric anomaly from the sea surface to the deep layer. The static stabilities in the chimney stations are unstable or neutral. This indicates that the winter time convection occurs. The JSPW sunken from the surface layer of chimney in winter spreads out under the Tsushima Warm Current area, following the isosteric surface of about 76 cl/t in Potential thermosteric anomaly. The formation of the deep water of the JSPW is mainly affected by the cooling of the sea surface than the evaporation of winds because the temperature and the salinity on the isoteric surface of about 76 cl/t in potential thermosteric anomaly ate cold and low The phenomenon of chimney occurred in here and there of the area in the north of 40" 30'N, west of 138" E. This suggests that the deep water of the JSPW is formed not in a limited area but probably in the overall region of the northern open ocean.