• Journal of Korean Society of Environmental Engineers
• /
• v.34 no.2
• /
• pp.73-78
• /
• 2012

In this study, three different synthetic musk compounds (SMCs) in the Nakdong river water (raw water) and rapid sand filtered water were treated by $O_3$ process. The experimental results showed that the removal efficiency of musk ketone (MK) was lower than removal efficiency of AHTN (7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene) and HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[c]-2-benzopyran) for both the raw water and the rapid sand filtered water. And in general, the removal efficiencies of three SMCs in the raw water were lower than that in the sand filtered water. Under the $O_3$ dose of 0.5~10.0 mg/L, the removal rate constants (k) of three SMCs for the raw and sand filtered waters increased rapidly with the increased $O_3$ dose. In the case of drinking water treatment plants (DWTPs) which were selected pre- and post-$O_3$ processes (located in the downstream of Nakdong River), operation conditions of pre- and post-$O_3$ process were $0.5{\sim}2.0mg{\cdot}O_3/L$ (2~4 min) and $0.5{\sim}2.5mg{\cdot}O_3/L$ (6~8 min). Therefore, $O_3$ doses and contact times of same conditions with above were very difficult to remove SMCs in DWTPs.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.6
• /
• pp.1351-1360
• /
• 1993

The fatigue behavior of GFRP composites is affected by environmental parameters. Therefore, we have to study on effect of sea water on fatigue behavior of GFRP composites as to maintain the safety and confidence in design of ocean structure of GFRP. In this paper, we investigated the fatigue properties of chopped strand glass mat/polyester composite in synthetic sea water. (pH 8.2) In case of the glass fiber (CSM type) reinforced polyester composite materials, the fatigue crack in the both dry and wet specimens tested in air or synthetic sea water occurred at the initial of cycle. Thereafter, it was divided with two regions that one decreased with the crack extension and the other increased with the crack extension. The transition point occurred during the crack propagation shifted to high ${\Delta}K$ value as load increase but its point is not changed regardless of immersion or test environment under a constant load. The synthetic sea water degrades the bond strength between fiber and matrix, thereby the tendency of rapid deceleration and acceleration of the crack growth was appeared.

• Water for future
• /
• v.8 no.2
• /
• pp.54-55
• /
• 1975

• Proceedings of the Korea Water Resources Association Conference
• /
• 2002.05a
• /
• pp.257-262
• /
• 2002

• Proceedings of the Korea Water Resources Association Conference
• /
• 1985.07a
• /
• pp.7-16
• /
• 1985

본 연구는 유역 추적에 자주 쓰이는 합성단위 유량도(synthetic unit hydrograph) 방법의 하나인 Snyder 방법에 있어서의 계수를 남한강수계에서 재조정하는 과정(procedure)을 제시하였다. 그 과정을 간략하게 설명하며, 이전에 구한 남한강 수계에서의 snyder 계수를 초기치로 하여 HEC-1 program을 이용하여 계수를 재조정한다. 이와 같은 과정을 통하여 재조정된 계수는 그 전의 계수에 의한 합성단위 유량도보다 지체시간($$)이 작아지고 첨두(peak)값이 커지는 특성을 가지고 있다.

• Journal of environmental and Sanitary engineering
• /
• v.5 no.2
• /
• pp.95-102
• /
• 1990

Since the production of synthetic detergents in 1966, the demand of detergents increased rapidly during the past in Korea. Its production which was solely for donlestic consumption leaped from 402 tons in 1966 to 259387 tons in 1989. Practically all of these products were the anionic detergents primarily sodium salts of Alkyl Benzene Sulfonate(ABS). ABS persists for long periods in stream because of its resistance to triodegradation. Therefore synthetic detergents have been considered major contributors to water pollution. The detergents give a raise to be noted is foaming at sewage treatment plant and the drinking water contaminated by detergents have often been accompanying taste and odor. So the biodegradable Linear Alkyl benzene Sulfonate(LAS) has been adapted as the substituents for the Alkyl Benzene Sulfonate (ABS) since the 1980. However, the Inassive bubbles stemmed from use of synthetic detergents in the sewage treatment plant and the branch of tile Han River had been reported. Therefore, this investigation less undertaken so as to know the pollution of detergents in domestic sewage and the receiving river, and determine the biodegradation of synthetic detergents since ABS has been replaced by LAS in 1980. The study results on the pollution and biodegradation of synthetic detergents were as follows . 1. The major streams in Seoul were contaminated by synthetic detergents. The concentration of detergents were 2.48 mg/l of Anyangchon. 2. The biodegradation were determined by spontaneous settling and aeration. Since the LAS was substitute for ABS in 1980, detergents was more easy to biodegradable. The reduction ratio of Tanchon, Chungranchon, and Anyangchon were 15% , 11% and 16% by the settling and 76%, 77% and 82% by aerations for 5 days.

• Journal of Korean Society of Water and Wastewater
• /
• v.21 no.3
• /
• pp.273-278
• /
• 2007

Modern society has moved from a phosphorus recycling loop, where animal manure and human wastes were spread on farming land to recycle nutrients, to a once-through system, where phosphates are extracted from mined, non-renewable phosphate rock and end up either in landfill(sewage sludge, incinerator ash) or in surface waters. In this research, crystallization of nitrogen and phosphate with natural sources of $Mg^{2+}$ in synthetic water was tested. The operational parameters of pH, mixing time, and the magnesium molar ratio were investigated to find optimal conditions of the MAP precipitation using synthetic wastewater. The removal efficiency of phosphate increased with pH up to 11. By MAP precipitaiton of the synthetic waste water, 94% of the phosphate were eliminated at pH 11. It was found that at least 10 minutes mixing time was required and 20 minutes mixing time was recommended for efficient phosphate removal. High efficiency removal of phosphate was possible when the magnesium molar ratio was 1.0~2.0. The comparative study of different magnesium sources showed that coagulants (PAC) was the more efficient sources than only magnesium. The result showed that 97% of phosphate removal. In conclusion, coagulants (PAC) induced crystallization of struvite and hydroxyapatite was shown to be a technically viable process that could prove cost effective for removing phosphate in wastewater.

• Corrosion Science and Technology
• /
• v.4 no.5
• /
• pp.178-190
• /
• 2005

In order to develop a new corrosion sensor for detecting and monitoring the external and internal corrosion damage of buried pipeline, the electrochemical property of sensors and the correlation of its output to corrosion rate of steel pipe, were evaluated by electrochemical methods in two soils of varying resistivity (5,000 ohm-cm, 10,000 ohm-cm) and synthetic tap water environments. In this paper, two types of galvanic probes were manufactured: copper-pipeline steel (Cu-CS) and stainless steel-pipeline steel (SS-CS). The corrosion behavior in synthetic groundwater and synthetic tap water for the different electrodes was investigated by potentiodynamic test. The comparison of the sensor output and corrosion rates revealed that a linear relationship was found between the probe current and the corrosion rates. In the soil resistivity of $5,000{\Omega}-cm$ and tap water environments, only the Cu-CS probe had a good linear quantitative relationship between the sensor output current and the corrosion rate of pipeline steel. In the case of $10,000{\Omega}-cm$, although the SS-CS probe showed a better linear correlation than that of Cu-CS probe, the Cu-CS probe is more suitable than SS-CS probe due to the high current output.

• Nuclear Engineering and Technology
• /
• v.53 no.11
• /
• pp.3563-3579
• /
• 2021

Measured decay heat data of light water reactor (LWR) spent nuclear fuel (SNF) assemblies are adopted to train machine learning (ML) models. The measured data is available for fuel assemblies irradiated in commercial reactors operated in the United States and Sweden. The data comes from calorimetric measurements of discharged pressurized water reactor (PWR) and boiling water reactor (BWR) fuel assemblies. 91 and 171 measurements of PWR and BWR assembly decay heat data are used, respectively. Due to the small size of the measurement dataset, we propose: (i) to use the method of multiple runs (ii) to generate and use synthetic data, as large dataset which has similar statistical characteristics as the original dataset. Three ML models are developed based on Gaussian process (GP), support vector machines (SVM) and neural networks (NN), with four inputs including the fuel assembly averaged enrichment, assembly averaged burnup, initial heavy metal mass, and cooling time after discharge. The outcomes of this work are (i) development of ML models which predict LWR fuel assembly decay heat from the four inputs (ii) generation and application of synthetic data which improves the performance of the ML models (iii) uncertainty analysis of the ML models and their predictions.

• Environmental Analysis Health and Toxicology
• /
• v.5 no.1_2
• /
• pp.37-44
• /
• 1990

Synthetic detergents and surfactants are in widespread usage as household and industrial detergents. Potential human toxic hazard arises following percutaneous absorption or oral ingestion of solution residues from kitchen and feeding utensils, fruits, and vegetables and contaminated water supplies. A toxicological investigations was performed with the synthetic detergents and surfactants [linear alkyl benzene sulfonate (LAS), ${\alpha}$-olefin sulfonate (AOS), sodium lauryl sulfonate (SLS), sodium lauryl ester sulfonate (SLES)］, In acute toxicity, agents were administered subcutaneously into ICR mice. In acute study, after lowering of spontaneous motility, respiratory failure, death appeared, vomitting was often associated with salivation and or retching. No sex difference was observed in LD$\sub$50/ of mice. In subacute toxicity, agents were administered orally into SD rats. Body weight increase was suppressed and there was no adverse effect on food and water consumption. The weight of organs were not changed by agents as compared with control group. No specific change was observed in biochemical and hematologicalor data.