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우라늄 分離定量에 있어서 Amberlite LA-2의 利用
尹鉉勝,鄭昌雄,金演斗 충남대학교 자연과학연구소 1980 學術硏究誌 Vol.7 No.2
The liquid anion exchanger, Amberite LA-2, has been used to separate the trace amount of uranium from synthetic graphite in sulfuric acid solution As reducing the impurity metals with NaHSO_(3) the complete extraction of uranium has been made successfully in organic phase. The mixed solution, NaOH-HClO_(4)-H_(2)O_(2), was found to be good solution for stripping and developing of the uranium complex.
이승현,곽봉순,이종형 金烏工科大學校 1998 論文集 Vol.19 No.-
A study on the fatigue divides the whole fatigue domain into six zones and therefore can guide the designer as to which prediction tool to use. being a function of crack length and stress amplitude. The fatigue domain has been divided into six different zones, each governed by a separate fatigue regime. The proposed predictions are to be considered as practical curve fitting relations for special case. but these cases can also be fairly general and useful for design purposes. The fatigue diagram can be used to show that experimental results should only be compared when they were measured in the same fatigue zone. and there by avoiding the possibility of confusion
염해손상을 입은 철근콘크리트 구조물의 내구성 증진을 위한 하부대단면 보강공법
박길현,박종환,양승현 朝鮮大學校 建設技術硏究所 2007 建設技術硏究 Vol.27 No.1
This paper deals with the strengthening method for the Increase durability of the reinforced concrete structures with Chloride Damage, and the purpose of this research is to develop the construction method and materials for extending the lower cross-section of the structures which is set up on the sea. Accordingly, a reinforced concrete pier, which has serious damage at the lower cross-section, is adopted as the subject structure for the study. In the cases of repairing or extending the lower cross-section for the structural reinforcement like the matter in this study, the most important component of choosing an method is the adhesion between the boundary sides of the existing and new concrete, and as the operation is taken on the sea, the material and method, which suit to the ocean surroundings and operating condition, should be chosen. The structural properties and operation condition taken into consideration, the material, which causes far less pollutant and have much better adhesion and strength, is developed, and with this material, this study indicates the best strengthening method to minimize the amount of rebound and to prevent the joints from breaking out. The lower cross-section extension work of the subject is executed with the newly-developed material and the method for strengthening, and as a result of the quality inspection, the material and method prove their superiority since the compression, ultimate and adhesion strength of the concrete was huge, and the adhesion between the glass fiber and the section extended is great. As the material and the strengthening method developed in this study bring about little possibilities of polluting the ocean, make it easy to operate on the sea, and have great adhesion not only between the existing and new concrete but also among each mortar layers, they are considered to be very suit to strengthening and extension of the reinforced concrete structure set up on the sea.
Water Quality and Cyanobacterial Anatoxin-a Concentration in Daechung Reservoir
( Seung Hyun Joung ),( Jee Hwan Kim ),( Chi Yong Ahn ),( Shin Sok Choi ),( Hee Sik Kim ),( Hee Mock Oh ) 한국하천호수학회 2002 생태와 환경 Vol.35 No.4
남조류에 의해 생성되는 anatoxin-a의 양과 환경요인과의 관계를 알아보기 위해 대청호에서 2001년 6월부터 2001년 11월까지 조류 및 물 시료를 채취하였다. 환경요인 중 물리적 요인은 현장에서 측정하였고, 생물·화학적 요인은 실험실에서 측정하였다. 조류 및 물 시료에 존재하는 anatoxin-a의 양은 fluorescence detector를 이용하여 HPLC로 측정하였고, 조류 시료와 물 시료의 경우 각각 0.61-8.68 ㎍/g dry wt, 0.01-0.08 ㎍/ℓ로 측정되었다. 음용수의 안전을 고려한 anatoxin-a의 권고 기준 농도는 1 ㎍/ℓ로 제안되고 있다. 조류세포와 물 시료에서 anatoxin-a 농도가 가장 높게 검출된 시기는 7월이었다. 독소 생성에 중요한 요인을 확인하기 위해 환경요인과 anatoxin-a 농도와의 상호관계를 살펴보았다. 조류 시료내 anatoxin-a 농도는 nitrate, 총질소와 총인 비율, 총용존질소(P<0.05) 및 총입자성질소와 총입자성인 비율(P<0.05)과 높은 상관관계를 나타내었고, 물 시료내 anatoxin-a 농도는 수온, 전기전도도(P<0.01), 수소이온농도, phycocyanin, phycocyanin과 엽록소 a 비율(P<0.01)과 높은 상관관계를 나타내었다. The current study was performed to elucidate the relationship between the anatoxin-a produced by cyanobacteria and aquatic environmental factors. Algal and water samples were collected from the Daechung Reservoir from June to November 2001. The physical factors of the water quality were measured in situ, while the biological and chemical factors were examined in the laboratory. The concentrations of anatoxin-a in the algal and water samples were analyzed by HPLG using a fluorescence detector and ranged from 0.61-8.68 ㎍/g dw in the algal samples and 0.01-0.08 ㎍/ℓ in the water samples. The suggested maximum concentration of anatoxin-a for safe drinking water is 1 ㎍/ℓ. The concentrations of anatoxin-a in the algal and water samples were highest in July. The relationships between the aquatic environmental factors and the anatoxin-a concentration were also analyzed to identify the crucial elements for toxin production. The anatoxin-a concentrations in the algal samples exhibited a high correlation with nitrate, the TN/TP ratio, TDN(P<0.05), and TPN/TPP ratio(P<0.01), whereas the anatoxin-a concentrations in the water samples were highly related to the water temperature, conductivity(P<0.01), pH, phycocyanin, and phycocyanin/chlorophyll a ratio(P<0.05).
Seung-Hyun Joung,Hee-Mock Oh,Kyung-A You 한국미생물학회 2016 The journal of microbiology Vol.54 No.8
This study was conducted to determine the environmental factors affecting the level of potentially toxic Microcystis. The long-term tendencies of temperature, precipitation, and water quality factors were analyzed to determine the environmental characteristics of the Daechung Reservoir in Korea, and water samples were directly collected to analyze the dynamics of toxic and non-toxic Microcystis at weekly intervals from May to October 2012. Microcystis was the dominant genus during the study period, and it was composed of potentially toxic and non-toxic Microcystis. The fraction of potentially toxic Microcystis ranged from 6.0% to 61.1%. The amount of toxic Microcystis was highly related to the intracellular microcystin concentration (r = 0.760, P < 0.01). Therefore, the fraction of potentially toxic Microcystis is an important concern in Microcystis blooming because the intracellular microcystin concentration may reflect microcystin levels in the water. The prevalence of potentially toxic Microcystis was highly related to water temperature in Daechung Reservoir (r = 0.585, P < 0.01). Thus, temperature increase during Microcystis blooming may lead to more frequent toxic Microcystis blooms in eutrophic water bodies.
Simple Method for a Cell Count of the Colonial Cyanobacterium, Microcystis sp.
Joung, Seung-Hyun,Kim, Choong-Jae,Ahn, Chi-Yong,Jang, Kam-Yong,Boo, Sung-Min,Oh, Hee-Mock The Microbiological Society of Korea 2006 The journal of microbiology Vol.44 No.5
The cell counting of colonial Microcystis spp. is a rather difficult and error-prone proposition, as this genus forms irregularly-shaped and irregularly-sized colonies, which are packed with cells. Thus, in order to facilitate a cell count, four methods of dividing the colonies into single cells were compared, including vortexing, sonication, $TiO_2$ treatment, and boiling. As a result, the boiling method was determined to generate the greatest number of single cells from a colony, and all colonies were found to have divided completely after only 6 min of treatment. Furthermore, no significant cell destruction, which might alter the actual cell density, was detected in conjunction with the boiling method (P=0.158). In order to compute the cell number more simply, the relationship between the colony size and the cell number was determined, via the boiling method. The colony volume, rather than the area or diameter was correlated more closely with the cell number ($r^2=0.727$), thereby suggesting that the cell numbers of colonial Microcystis sp. can also be estimated effectively from their volumes.
낙동강 물금 지점의 겨울 및 봄철 식물플랑크톤 생물량에 대한 기후변화 영향
정승현 ( Seung Hyun Joung ),박혜경 ( Hae Kyung Park ),이혜진 ( Hae Jin Lee ),이수형 ( Soo Hyung Lee ) 한국물환경학회 2013 한국물환경학회지 Vol.29 No.2
To confirm the relationship between climate change and Stephanodiscus in Mulgeum station of Nakdong River, Korea, this study was conducted. The temperature in crease by climate change was observed in the study site, where the temperature was gradually increased in most seasons, except for summer season. The mass proliferation of Stephanodiscus constantly appeared in every year, especially between November and March, and when Stephanodiscus abundance was above 90% in phyto plankton biomass. Among this period, phytoplankton biomass was high related with water temperature r2=0.249, p<0.01 than nutrient factors such as nitrogen and phosphorus in the study site. Finally, temperature by climate change can be regarded as the affecting factor for ch1.a variation, because temperature was strongly related with water temperature r2=0.748, p<0.01. From 1997 to 2010, the annual maximum phytoplankton biomass was recorded in the rang of temperature from 4.8 to 8.4, and the range was regarded as the temperature condition for the optimal growth of Stephanodiscus in the study site. On the optimal growth temperature, the trend of monthly average temperature correspondded to the trend of ch1.a variation from November to March. In future, the increase of temperature by climate change can prolong Stephanodiscus blooming period in winter and spring seasons.