• Journal of environmental and Sanitary engineering
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• v.23 no.4
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• pp.37-44
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• 2008

In this study we developed the analytical methods for the determination of three neurotoxin; anatoxin-a, saxitoxin and neosaxitoxin using HPLC/FLD system and this analytical methods were applied to real sample; algae culture and algae extracts. For the HPLC/FLD analysis of anatoxin-a samples were concentrated on WCX(Weak Cation Exchanger) SPE and then anatoxin-a in concentrate was derivatized with NBD-F solution. Supernatant was injected on HPLC system. For the HPLC/FLD analysis of saxitoxin and neosaxitoxin samples were separated on the column and then derivatizied by post column reactor for fluorescen detection. For post column reaction of saxitoxin we feed two kinds of reaction solution; Oxidizing Reagent of which composition was periodic acid(7mM) in 50mM potassium phosphate buffer, pH 9 and acidifying reagent of which Composition was 0.5M acetic acid. The LOD value for anatoxin-a, saxitoxin and neosaxitoxin in HPLC/FLD method was 24.3 ng. $35{\mu}g/L$, $27{\mu}g/L$ respectively. We determined the anatoxin-a content of lyophilized anabaena flos-aquae and $20{\mu}g/g$ d.w. of anatoxin-a was detected. We analyzed saxitoxin and neosaxitoxin in algae culture media and extracts of lypopyllized algal cell cultured and that of Deachung reservior. Saxitoxin and neosaxitoxin in real sample were below the limit of detection. Although there are various water treatment processes for removing neurotoxins were suggested no process give simultaneous and complete removal of neurotoxins. It was cocluded that nanofiltration which reject material by size can be a process for removal of neurotoxins.

• Archives of Craniofacial Surgery
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• v.19 no.3
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• pp.194-199
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• 2018

Background: Cases of simultaneous multiple skin cancers in a single patient have become more common. Due to the multiplicity of lesions, reconstruction in such cases is more difficult than after a single lesion is removed. This study presents a series of patients with multiple facial skin cancers, with an analysis of the surgical removal, reconstruction process, and the results observed during follow-up. Methods: We reviewed 12 patients diagnosed with multiple skin cancers on the face between November 2004 and March 2016. The patients' medical records were retrospectively reviewed to identify the type of skin cancer, the site of onset, methods of surgical removal and reconstruction, complications, and recurrence during follow-up. Results: Nine patients had a single type of cancer occurring as multiple lesions, while three patients had different skin cancer types that occurred together. A total of 30 cancer sites were observed in the 12 patients. The most common cancer site was the nose. Thirteen defects were reconstructed with a flap, while 18 were reconstructed with skin grafting. The only complication was one case of recurrence of basal cell carcinoma. Conclusion: Multiple skin cancers are removed by performing Mohs micrographic surgery or wide excision, resulting in multiple defect sites. The authors emphasize the importance of thoroughly evaluating local lesions surrounding the initially-identified lesions or on other sites when reconstructing a large defect which can not be covered by primary closure. Furthermore, satisfactory results can be obtained by using various methods simultaneously regarding the condition of individual patients, the defect site and size, and the surgeon's preference.

• Economic and Environmental Geology
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• v.35 no.3
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• pp.229-239
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• 2002

The objective of this study was to design an optimal electro-remediation system for TCE contaminated water using zero talent iron (ZVI) and direct current (DC). A series of column experiments were conducted to evaluate the effects of electrode arrangement and the location of permeable iron barrier in the column on the TCE removal efficiency and iron corrosion process. In twelve different combinations of ZVI and/or DC application in the test columns, the rate of reductive degradation of TCE was improved with simultaneous application of both ZVI and DC compared to that used ZVI only. The moot effective arrangement of electrode and ZVI for TCE removal from water was a column set with ZVI and cathode installed at the down gradient, respectively.

• Journal of Environmental Science International
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• v.28 no.11
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• pp.983-991
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• 2019

This study investigated the use of a hydroxyl-radicals-generated microbubble/catalyst (MB/Cat) system for removing organic pollutants, nitrogen, and phosphorous from liquid fertilizer produced by livestock wastewater treatment. Use of the MB/Cat system aims to improve the quality of liquid fertilizer by removing pollutants originally found in the wastewater. In addition, a reduction effect has been reported for antibiotics classified as representative non-biodegradable matter. Samples of liquid fertilizer produced by an aerobic biological reactor for swine wastewater treatment were first analyzed for initial concentrations of pollutants and antibiotics. When the MB/Cat system was applied to the liquid fertilizer, TCOD, TOC, $BOD_5$, and $NH_3-N$, and $PO_4-P$ removal efficiencies were found to be approximately 52%, 51%, 30%, 21%, and 66%, respectively. Additionally, Amoxicillin hydrate was removed by 10%, and Chlortetracycline HCl and Florfenicol were not present at detectable levels These findings confirm that the MB/Cat system can be used with livestock wastewater treatment to improve liquid fertilizer quality and to process wastewater that is safe for agricultural re-use.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.1
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• pp.39-46
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• 2011

NO oxidation is an important prerequisite step to assist the selective catalytic reduction (SCR) at low temperatures ($<200^{\circ}C$). Therefore, we conducted the lab- and bench-scales experiments appling the sodium chlorite powder ($NaClO_2(s)$) for the oxidation of NO to $NO_2$ and the carbon-based catalyst for the reduction of $NO_x$ and $SO_2$; the lab- and bench-scales experiments were conducted in laboratory and iron-ore sintering plant, respectively. In the lab-scale experiment, known concentrations of $NO_x$ (200 ppm), $SO_2$ (75 ppm), $H_2O$ (10%) and $NH_3$ (400 ppm) in 2.6 L/min were introduced into a packed-bed reactor containing $NaClO_2(s)$, then gases produced by the reaction with $NaClO_2(s)$ were fed into the carbon-based catalyst (space velocity = $2,000hr^{-1}$) at $130^{\circ}C$. In the bench-scale experiment, flue gases of $50Nm^3/hr$ containing 120 ppm NO and 150 ppm $SO_2$ were taken out from the duct of iron-ore sintering plant, then introduced into the flow reactor; $NaClO_2(s)$ were injected into the flow reactor using a screw feeder. Gases produced by the reaction with $NaClO_2(s)$ were introduced into the carbon-based catalyst (space velocity = $1,000hr^{-1}$). Results have shown that, in both lab- and bench-scales experiments, NO was oxidized to $NO_2$ by $NaClO_2(s)$. In addition, above 90% of $NO_x$ and $SO_2$ removal were obtained at the carbon-based catalyst. These results lead us to suggest that the combination of $NaClO_2(s)$ with the carbon-based catalyst has the potential to achieve the simultaneous removal of $NO_x$ and $SO_2$ at low temperature ($<200^{\circ}C$).

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.185-188
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• 2003

오염된 지하수 정화에 있어 반응벽체(Permeable Reactive Barriers, PRBs)를 이용한 정화기법은 최근 가장 큰 관심을 모으고 있는 기술이다. 반응벽체의 적용에 있어 가장 중요한 사항은 오염물질의 특성을 고려하여 적절한 반응성을 가지는 충진물질을 선택하는 일이다. 지금까지 연구된 반응물질 중 제올라이트는 취득이 용이하고 가격이 저렴하여, 암모늄이나 중금속과 같은 양이온성 오염물질의 정화에 그 적용성을 인정받아왔다. 하지만 표면에 음전하를 띠는 제올라이트의 특성 때문에, 지하수내에서 음이온의 형태로 존재하는 Cr(VI) 등에는 반응성이 없는 것으로 알려져 왔다. 이에 본 연구에서는 제올라이트에 영가철을 결합한 ZanF란 물질을 개발하여 양이온성 중금속의 하나인 납과 음이온성 중금속의 하나인 Cr(VI)을 동시 제거하는 실험을 수행하였다. 실험결과 ZanF는 초기농도 2-15mmol를 가지는 납 오염용액에 대해 90% 이상의 제거율을 보였으며, 초기농도 0.1 mmol을 가지는 Cr(VI) 오염용액의 농도를 5시간 내에 검출한계 이하로 떨어뜨리는 탁월한 효과를 보였다. 실험결과를 토대로 ZanF는 납과 Cr(VI)으로 동시에 오염된 지하수 정화에 효과적으로 사용될 수 있으리라 기대된다.

• 한국연소학회:학술대회논문집
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• 1997.06a
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• pp.69-76
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• 1997

Industrial-scale pulse corona process to remove $SO_2$ and $NO_x$ simultaneously from combustion flue gas has been studied. The pilot plant built in the present study treats 2,000 $Nm^3$/hr of flue gas from a boiler. The geometry of the pulse corona reactor is similar to that of an electrostatic precipitator commonly used in industry, A thyratron switch and magnetic pulse compressors, which can generate up to 130 kV of peak pulse voltage and up to 30 kW of average pulse power, have been used to produce pulsed corona. The removal efficiencies of $S0_2$ and $NO_x$ with the present process are maximum of 95 % and 85 %, respectively. Electrical power consumption to produce the pulsed corona, which has been one of the major difficulties to apply this process to industry, has been evaluated in the present study. The results showed that the power consumption can be reduced significantly by simultaneous addition of hydrocarbon injection and heterogeneous phase reactions to the process.

• Advances in materials Research
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• v.1 no.2
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• pp.129-146
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• 2012

Polycrystalline diamond is an ideal material for parts with micro-holes and has been widely used as dies and cutting tools in automotive, aerospace and woodworking industries due to its superior wear and corrosion resistance. In this research paper, the modeling and simultaneous optimization of multiple performance characteristics such as material removal rate and surface roughness of polycrystalline diamond (PCD) with ultrasonic machining process has been presented. The fuzzy logic and taguchi's quality loss function has been used. In recent years, fuzzy logic has been used in manufacturing engineering for modeling and monitoring. Also the effect of controllable machining parameters like type of abrasive slurry, their size and concentration, nature of tool material and the power rating of the machine has been determined by applying the single objective and multi-objective optimization techniques. The analysis of results has been done using the MATLAB 7.5 software and results obtained are validated by conducting the confirmation experiments. The results show the considerable improvement in S/N ratio as compared to initial cutting conditions. The surface roughness of machined surface has been measured by using the Perthometer (M4Pi, Mahr Germany).

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.2
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• pp.152-160
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• 2016

The market demand for diesel engine tends to increase in general passenger cars as well as commercial vehicles because of its advantages. However, to meet the vehicle emissions regulation which will be more stringent in the future, it is necessary to plurally apply all after-treatment technologies such as diesel oxidation catalyst (DOC), catalyzed diesel particulate filter (CDPF), lean NOx trap (LNT) and selective catalytic reduction (SCR), and so on. Accordingly, the exhaust after-treatment system for diesel vehicle requires the technology of minimizing the numbers of catalysts by integrating every individual catalysts. The purposes of this study is to develop hybrid exhaust after-treatment device system which simultaneously uses LNT/DPF and SCR/DPF catalyst concurrently reducing NOx and particulate matter (PM). As the results, the hybrid system with $NH_3$ generated at LNT/DPF working as a reducing agent of SCR/DPF catalyst, improving NOx conversion rate, was found to be more excellent in de-NOx performance than that in LNT/DPF alone system.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.10a
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• pp.113-116
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• 2000

The purpose of this study is to present a method for determining the k most vital arcs in shortest path problem using an evolutionary algorithm. The problem of finding the k most vital arcs in shortest path problem is to find a set of k arcs whose simultaneous removal from the network causes the greatest increase in the total length of shortest path. The problem determining the k most vital arcs in shortest path problem has known as NP-hard. Therefore, in order to deal with the problem of real world the heuristic algorithm is needed. In this study we propose to the method of finding the k-MVA in shortest path problem using an evolutionary algorithm which known as the most efficient algorithm among heuristics. For this, the expression method of individuals compatible with the characteristics of shortest path problem, the parameter values of constitution gene, size of the initial population, crossover rate and mutation rate etc. are specified and then the effective genetic algorithm will be proposed. The method presented in this study is developed using the library of the evolutionary algorithm framework (EAF) and then the performance of algorithm is analyzed through the computer experiment.