• Journal of Korean Society of Water and Wastewater
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• v.30 no.1
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• pp.1-8
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• 2016

Temperature correction trans-membrane pressure (TC-TMP) is frequently used as a fouling index in membrane water treatment plants. TC-TMP equation is derived based on an assumption that the total membrane resistance (i.e. the sum of the intrinsic membrane resistance and fouling resistance) is not affected by temperature. This work verified the validity of this assumption using microfiltration (MF) and ultrafiltration (UF) membranes with and without fouling. The foulants used in the work were kaolin (inorganic) and humic acid (organic). The intrinsic resistances of MF and UF membranes remains at constant values regardless of temperature change. When the same amount of foulants were accumulated on the membrane, inorganic fouling resistance with kaolin was constant regardless of temperature change while organic fouling resistance with humic acid decreased at higher temperatures, which means that TC-TMP cannot be used as a fouling index when organic fouling occurs in a real field application. Since TC-TMP underestimates the amount of fouling at higher temperatures, more attention should be necessary in the operation of membrane water treatment plant in a hotter season like summer.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1838-1844
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• 2007

The Wonhyo Tunnel on KTX railroad line is a section of latest concerns from domestic environmental NGOs, which focus on potential destruction of ecosystem or the like due to ever-depleted swamp water at about 300m upward from the tunnel under construction. As a result of study, out of all swamps in the vicinity of the tunnel, it was found that Mujechi 1st and 2nd swamps have been getting smaller in their area little by little since 50 years ago primarily under the influence of eroded streams around lower swamp and even ever-increasing annual mean temperature. As the result of monitoring about swamp before work, it was found that swamp water depends absolutely on amount of rainfall. Besides, the results of monitoring during work also didn't show any leakage generated in the tunnel during and after excavation works with regard to a wheat field swamp in the most vicinity of the tunnel (80m away). On the other hand, it was found that the range affected by ground water sink in tunnel section without grouting process amounted to about 100m around the tunnel, which indicates that such ground water sink has no significant impact upon most of swamps near the tunnel. As the result of testing by two well tracer test around swamps, it was noted that swamp water didn't run out from the bottom of swamp even with adjacent ground water level sunk in factitious ways. And the results of physical survey showed that swamp kept saturated even in dry season when ground water level becomes lower than the bottom of swamp. Therefore, even supposing that ground water level becomes sunk due to tunnel works, it is estimated that the water level of swamps would be still kept owing to impervious layer(peat beds).

• Explosives and Blasting
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• v.10 no.4
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• pp.6-18
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• 1992

This Test Blasting aims to dig pier foundation in the water, therefore the Caps & Powder needs 5-20% more Than the amount of ground blasting works. It results in the Dimension of water blasting standardization This project is Contracted with th office of HAM River Development of Kyunggi province.

• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.10-15
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• 2010

The performance analysis of water systems is very important to urban disaster mitigation. It will benefit the task of preparedness and emergency response through a more practical and more quantitative approach. In this research work, an overview of hydraulics of water system has been provided. A methodology for such implementation based on scenario simulation and hydraulic analysis has been developed. The water system of Taipei Water Department was selected as a test bed for case study. Its serviceability following a major earthquake around Taipei metropolitan area has been quantified.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.6
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• pp.570-579
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• 2010

Since the temperature of waste heat source is relatively low, it is difficult to maintain high level of efficiency in power generation when the waste heat recovery is employed in the system. In an effort to improve the thermal efficiency and power output, use of ammonia-water mixture as a working fluid in the power cycle becomes a viable option. In this work, the performance of ammonia-water mixture based Rankine cycle is thoroughly investigated in order to maximize the power generation from the low temperature waste heat. In analyzing the power cycle, several key system parameters such as mass fraction of ammonia in the mixture and turbine inlet pressure are studied to examine their effects on the system performance. The results of the cycle analysis find a substantial increase both in power output and thermal efficiency if the fraction of ammonia increases in the working fluid.

• Nuclear Engineering and Technology
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• v.44 no.7
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• pp.709-718
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• 2012

The pressurized water reactor APR1400 adopts DVI (Direct Vessel Injection) for the emergency cooling water in the upper downcomer annulus. The International Standard Problem number 50 (ISP-50) was launched with the aim to investigate thermal hydraulic phenomena during a 50% DVI line break scenario with best estimate codes making use of the experimental data available from the ATLAS facility located at KAERI. The present work describes the calculation results obtained for the ISP-50 using the RELAP5/MOD3.3 system code. The work aims at validation and assessment of the code to reproduce the observed phenomena and investigate about its limitations to predict complicated mixing phenomena between the subcooled emergency cooling water and the two-phase flow in the downcomer. The obtained results show that the overall trends of the main test variables are well reproduced by the calculations. In particular, the pressure in the primary system show excellent agreement with the experiment. The loop seal clearance phenomenon was observed in the calculation and it was found to have an important influence on the transient progression. Moreover, the collapsed water levels in the core are accurately reproduced in the simulations. However, the drop in the downcomer level before the activation of the DVI from safety injection tanks was underestimated due to multi-dimensional phenomena in the downcomer that are not properly captured by one-dimensional simulations.

• Journal of Environmental Science International
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• v.13 no.1
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• pp.11-17
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• 2004

The purpose of this study is to present the model of ecological restoration through analysis on the condition of hydrach succession process in brackish water lake. To this study, we investigate and research the present condition of brackish water lake in South Korea. Most brackish water lake in South Korea have characteristics that is come into being malignant hydrach succession. Many lakes were reclaimed to increase foodstuff production. And river conservation work seperate lakes from the ocean. In a embryological view, most lakes based on the brackish water lakes, But present lakes show many different types such as a fresh water lake, a salt lake, a brackish water lake, a swamp, and a marshland. As a result, brackish water lakes have greatly damaged by diverse artificial interventions to promote people's activities. Therefore, in order to manage brackish water lakes systematically, criteria of lake preservation must be coincide with the present conditions of hydrach succession in each lake.

• Journal of Industrial Technology
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• v.28 no.A
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• pp.125-132
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• 2008

As of 2003, construction waste has been produced at the level of 130,614.8 tons/day, in which the amount of waste concrete was 92,639.1 tons/day and accounted for about 66.4% of the amount of construction waste. Waste concrete is mainly produced in construction work and civil engineering work. Especially, road surface crushing method using a large amount of water requires thorough management of concrete wastewater. The aim of this study was to analyze water pollution due to concrete wastewater generated in repair of bridge deck using road surface crushing equipment and to suggest reasonable countermeasures for solve the problem. In this study, it was surveyed current conditions of produced concrete wastewater in bridge deck repair, analyzed physical features of concrete wastewater, expected effects of water pollution on inflow rivers if it is not treated, established treatment plan of water pollution by categories, and calculated capacity of each treatment process and required amount of necessary chemicals. As a result of sampling wastewater generated in field sites and testing it at a lab scale, it was revealed that the original wastewater was produced in removing concrete from bridge deck slabs using surface crushing equipment whose pH was 12.53, CODMn was 12.910mg/L, SS was 547.0mg/L, and other heavy metals were included in extremely small quantities.

• Environmental Engineering Research
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• v.15 no.2
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• pp.85-91
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• 2010

Romania aims to adopt and implement the European Union's legislation, also including that for the field of water management. Like other countries, groundwater in Romania is locally polluted from point sources, such as leaking landfills, as well as from diffuse pollution sources, include fertilizers, pesticides and leakages from sewers, in urbanized areas. Diffuse pollution can also occur indirectly, by over-exploitation of groundwater wells, resulting in salt water intrusion, as well as from mining and exploitation of mineral aggregates. Romania has quite an intensive monitoring scheme to measure groundwater quality in phreatic and confined aquifers. The purpose of the work resumed in this paper was to derive natural background levels (NBL) for groundwater in order to distinguish the natural elevated concentrations of some substances (natural phenomena) from point and diffuse pollution (anthropogenic phenomena). Based on these NBLs, threshold values (TV) for groundwater will be set according to the requirements of the European Water Framework Directive and the related Groundwater Directive. This paper describes the results of a study for the derivation of NBL and TV in a pilot Groundwater Body. Also, the process and draft results for extrapolating this work for all Romanian groundwater bodies is explained, as well as points for future consideration with respect to monitoring and management.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.72-76
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• 2004

Wetland is an important eco-system on the earth and can effectively control agricultural non-point source pollution. Reed is a typical wetland plant for land/inland water ecotone in north China. The studies indicated that reed had a underground rooted-stem, which formed a 'high speeded-connecting vessels' i.e. reed root channel (RRC) in Baiyangdian lake of Hebei province. It spread predominantly along horizontal direction underground and are mainly distributed at 18-75 cm. The results of field work from healthy reed-wetland (HRW) and regarded reed-wetland (RRW) showed that the reed, averagely, in HRW is 4.2 m height, 1 cm diameter, 65/m2 density; in RRW is 2.4 m height, 3 mm diameter, 86/m2 density. These results indicated the regradation of the function of RRC in RRW. The results of laboratory work of sewage purification from reed soil column (RSC) $(0\~100cm)$ and wheat soil column (WSC) showed that the efficiency of purification to sewage, in RSC, is high than in WSC, especially for phosphorus. The efficiency of purification, in RSC, is $92.6\%$ for total phosphorus, $43.5\%$ for total nitrogen, $54.1\%$ fur COD, respectively; in WSC, is $86.0\%$ for total phosphorus, $241.3\%$ for total nitrogen, $29.8\%$ for COD, respectively.