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이온크로마토그래프를 이용한 수중의 퍼클로레이트 농축 및 분석
김학철,Kim, Hak-Chul 대한환경위생공학회 2006 대한환경위생공학회지 Vol.21 No.4
This study included the development of analytical method for determining perchlorate in water sample. The analytical condition was referred in EPA 314.0 method which use ion chromatography and the concentrator column was replaced by the guard column. Concentrating 10mL raw or treated water sample on to AGl6 guard column made it possible to get the LOD(Limit of Detection) of $0.73\;{\mu}g/L$. The total run time was 11 minutes and during run time next sample could be concentrated on AGl6 guard column. Compared to the Concentration method which needed manual operation, the Direct Injection method could screen the many water samples. The LOD of the Direct Injection method was higher and the sensitivity was lower than that of the Concentration method. The RSDs(Relative Standard Deviations) were lower than 2.5 % for peak height and 0.7 % for retention time in pre-concentration methods. This method Showed good reproducibility and reliability and it was thought the deviations of recovery value could be reduced by considering column capacity and making water sample homogeneous. Matrix Elimination could be done using the pre-concentration method if perchlorate were in complex matrix of sample.
배양조류 및 댐 저수지 조체중 신경독소 Anatoxin-a, Saxitoxin류의 분석 및 수처리방안
김학철(Hak-Chul Kim),최일환(Il-Whan Choi) 대한환경위생공학회 2008 대한환경위생공학회지 Vol.23 No.4
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 ㎍/L, 27 ㎍/L respectively. We determined the anatoxin-a content of lyophilized anabaena flos-aquae and 20 ㎍/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.
김학철(Hak-chul Kim),최일환(Il-whan Choi) 대한환경위생공학회 2009 대한환경위생공학회지 Vol.24 No.2
Unusual bloom of toxic cyanobacteria in water bodies have drawn attention of environmentalists world over. Major bloom of Anabaena, Microcystis in water storage reservoir, rivers and lake leading to adverse health effects have been reported from Australia, England and many part of the world. These cyanobacterial cells can release intercellular matter like toxin in water and these intercellular matter can increase the concentration of organic matter. Cellysis can occur when algal cells meet the disinfectants like chlorine in water treatment plant and the resultant rising up of DOC(Dissolved Organic Carbon) or TOC(Total Organic Carbon) can increase the formation of disinfection by products. Disinfectants that kill microorganisms react with the organic or inorganic matter in raw water. In general disinfectants oxidize the matter in raw water and the resultant products can be harmful to human. There are always conflict about which is more important, disinfection or minimizing disinfection by products. The best treatment process for raw water is the process of the lowest disinfection by products and also the the lowest microorganism. In this study the cultured cells, Microcytis Aeruginosa(MA), Anabaena Flos-aquae(AF), Anabaena Cylindrica(AC), and the cells obtained in Daechung Dam(DC) whose dominant species was Anabaena Cylindrica were subjected to chlorination. Chlorination oxidizes inorganic and organic compounds and destruct live cells in raw water. Chloroform was analyzed for the cultured cells which were treated with 20㎎/ℓ dose of chlorine. In general chloroform is easily formed when dissolved organic matter react with chlorine. The cultured cells contributes the concentration of dissolved organic carbon and also that of total organic carbon which might be potent precusors of chloroform formed. The correlations of the concentration of chloroform, DOC and TOC were investigate in this study.
김학철 ( Hak Chul Kim ),최일환 ( Il Whan Choi ) 한국환경분석학회 2009 환경분석과 독성보건 Vol.12 No.4
In general, chloride and sulfate ions in soil can be extracted with deionized water and then each ion can be measured by a wet chemistry method or an ion chromatography method. The Korea Standard Method for Soil Samples does not include methods for chloride and sulfate ion. The method for evaluating the degree of soil corrosion is used to determine chloride and sulfate ions in soil. In the method, chloride and sulfate ions are extracted from soil samples and then analyzed by a wet chemical or an ion chromatographic method described in the Korean Drinking Water Analytical Method and in KS I ISO 11 11048. In this study, extraction efficiencies of chloride and sulfate ions from soil samples at different temperatures were investigated. In short, extraction of sulfate ion from soil was more influenced by temperature change than that of chloride ion. This phenomenon could be explained by the drastic change of the solubility of sulfate salts and nearly constant solubility of chloride salts. It was also observed that the contact time of the soil and extractant might result in the increase of extracted sulfate ions.
HOT 데이터 블록 병합 지연을 이용한 효율적인 플래시 메모리 로그 버퍼 관리 기법
김학철(Hak-Chul Kim),박용훈(Yong-Hun Park),윤종현(Jong-Hyeong Yun),서동민(Dong-Min Seo),송석일(Suk-Il Song),유재수(Jae-Soo Yoo) 한국콘텐츠학회 2010 한국콘텐츠학회논문지 Vol.10 No.1
본 논문에서는 데이터의 접근성에 따른 병합 가치를 고려한 새로운 로그 버퍼 관리 기법을 제안한다. 제안하는 기법은 로그 블록의 병합 가치를 평가하여 빈번하게 갱신이 발생하지 않는 데이터에 대해서 데이터 블록과의 병합연산을 수행한다. 또한 빈번하게 갱신되는 데이터에 대해 데이터 블록과의 병합을 최대한 지연한다. 이를 통해 불필요한 데이터 블록의 병합 연산을 방지하여 플래시 메모리의 소거 연산 횟수를 크게 감소시켰고, 공간 활용을 극대화 하였다. 마지막으로, 로그 버퍼 관리 기법의 대표적인 기법인 BAST와 FAST와의 성능 비교를 통해 본 논문에서 제안하는 기법의 우수성을 증명하였다. 성능평가 결과 제안하는 기법이 BAST와 FAST에 비해 소거연산 측면에서 평균 25%와 65%의 성능 향상이 있었다. In this paper, we propose a new log buffer management scheme considering the accessibility of the data. Our proposed scheme evaluates the worth of the merge of log blocks. It conducts the merge operations between infrequently updated data and the data blocks and postpones as much as possible the merge operations between frequently updated data and the data blocks. As a result, the proposed method prevents the unnecessary merge operations, reduces the number of the erase operations, and improves the utilization of the flash memory storage. In order to show the superiority of the proposed scheme, we compare it with BAST and FAST. It is shown through performance evaluation that the proposed method achieves about 25% and 65% performance improvements over BAST and FAST on average in terms of the number of the erase operations.