• Journal of the Korean Chemical Society
• /
• 제44권1호
• /
• pp.74-80
• /
• 2000

The purpose of this study is to analyze comparatively and improve the preparation of chlorine gas in the high school chemistry II textbooks on the basis of the revised curriculum. From the results of the preparation experiment of chlorine gas which is commonly dealing with 9 kinds of textbook in the nation, we have found some problems and have suggested the solution of these problems. The problem is the students may inhale the chlorine gas that is to be injurious on the human body, so the research is focused on safe experimental method without inhalation of chlorine gas. The simple conviction method of character in laboratory is to propose at 5 kinds.

• Proceedings of the Korean Fiber Society Conference
• /
• 한국섬유공학회 1998년도 가을 학술발표회논문집
• /
• pp.114-117
• /
• 1998

양모의 수축은 양모를 습윤 처리할 때 양모 스케일의 모근과 모단방향의 마찰계수가 다르기 때문에 일어나는 현상이므로 양모의 스케일을 화학적으로 개질하여 두 방향의 마찰계수의 차를 감소시키면 양모의 수축을 감소시킬 수 있다. 이와 같은 원리로 방축효과를 주는 양모의 방축 가공제로는 90% 이상이 염소 또는 염소를 발하는 물질인데 이 가공으로 인한 폐수는 환경문제를 일으키는AOX를 함유하고 있어서 이를 대체하고자 하는 연구가 여러 곳에서 진행되고 있다. (중략)

• Journal of the Korea Concrete Institute
• /
• 제15권4호
• /
• pp.606-614
• /
• 2003

The major cause of deterioration for the concrete bridge decks exposed to de-icing chemicals would be chloride-induced reinforcement corrosion. Thus, in this paper, in order to predict time to corrosion for concrete bridge decks in the urban area, chloride concentration was measured with depth from the surface. A frequency analysis on surface chloride concentration and chloride diffusion coefficient of concrete bridge deck equals 0.192, 29.828 in the scale parameter and 7.899, 1.983 in the shape parameter of gamma distribution. The average value of surface chloride concentration equals 1.5 kg/㎥ and condenses from 1 to 2 kg/㎥ in the level of probability 70%. From the probabilistic results, it is confirmed that 26mm of minimum cover depth in order to target 20 years over is calculated. The countermeasure strategy to extend the service life of concrete bridge deck exposed to de-icing chemicals would be an effective method to increase cover depth and to place high performance concrete, which could lead to reduce the chloride diffusion coefficient and distribution range.

• Environmental engineer
• /
• 통권36호
• /
• pp.18-21
• /
• 1989

• Environmental engineer
• /
• 통권35호
• /
• pp.26-28
• /
• 1989

• Environmental engineer
• /
• 통권34호
• /
• pp.36-37
• /
• 1989

• Applied Biological Chemistry
• /
• 제23권1호
• /
• pp.58-63
• /
• 1980

Present investigation is undertaken to evaluate residues of organochlorine pesticides and PCBs in river sediments and cultivated soils by GLC. Main sampling areas chosen were three industrial estates, Suwon, Iri and Kumi. Samples consist of river sediments and cultivated soils, in Suwon, Iri and Chilgok, which are likely to be accumulated with PCBs from nearby factories. Organochlorine pesticide residues were found in all sediments and soil samples while no PCBs residue was detected in all samples analyzed. The pesticide residues were greatest in the Suwon and least in Chilgok soils. p,p'-DDT and BHC isomers $({\alpha}-,\;and\;{\gamma}-)$ were found in all soil samples. p,p'-DDT, at the range of 0.006-0.840 ppm, was the most abundant residues among organochlorine insecticides.

• Journal of the Korean Recycled Construction Resources Institute
• /
• 제12권2호
• /
• pp.206-213
• /
• 2024

The present study concerns the inhibition of Calcium Nitrite Inhibitor(Ca(NO₂)₂) in mortar contaminated by chloride ions. Thus, the corrosion resistance and chloride transport were measured for the mortar containing calcium nitrite inhibitor. As a result, an increase in the dosage of calcium nitrite inhibitor resulted in an increase in the chloride threshold concentration for reinforcement corrosion, while the rate of chloride transport was accelerated. However, the calcium nitrite inhibitor could not guarantee the time to corrosion, due to the increased mobility of chlorides. To ensure the passivity of steel, the dosage of calcium nitrite inhibitor must exceed a certain dosage, ranging from 2.0~3.0 % by cement weight.

• Journal of Veterinary Clinics
• /
• 제31권3호
• /
• pp.199-205
• /
• 2014

Acidosis conditions either acute or chronic following ingestion of excessive amounts of readily fermented carbohydrate are great production problems for goat in Bangladesh. This study designed to investigate the prevalence of lactic acidosis and then response to different therapeutic agents. For this purpose, 1,128 goat were examined at outdoor District Veterinary Hospital, Faridpur, Bangladseh for treatment of which 40 goats were found positive for lactic acidosis showing 3.55% prevalence of disease. The highest occurrence found in female (4.64%) of over 3 years age (4.64%) in indigenous goat (2.7%). For therapeutic assessment the forty affected goats were divided into four groups A, B, C and D comprising of 10 animals each. Group A were given magnesium hydroxide 8% w/v at 1 g/kg body weight orally. In group B magnesium hydroxide 8% w/v at a dose as group A combination with 7.5% sodium bicarbonate at the rate of 0.9 ml/Kg body weight intravenously administered. Goat in group D were treated with mixture of ginger, nuxvomica, sodium carbonate, cobalt sulphate, dried ferrous sulphate and thiamin mononitrate at the rate of 1 g/kg body weight orally. Goat of group C treated with combination drugs of group A, B and D. The rectal temperature, pulse rate, respiration rate, was performed before and after treatment. It was found that the highest recovery in group C with an average period of $21{\pm}1.8$ hours. It was concluded that lactic acidosis is a common disease of goats and its severity can be effectively reduced by using combination drugs.

• Korean Journal of Environmental Biology
• /
• 제17권2호
• /
• pp.129-138
• /
• 1999

Chlorinated aromatic compounds are one of the largest groups of environmental pollutants as a result of world-wide distribution by using them as herbicides, insecticides, fungicides, solvents, hydraulic and heat transfer fluids, plasticizers, and intermediates for chemical synthesis. Because of their toxicity, persistence, and bioaccumulation, the compounds contaminated ubiquitously in the biosphere has attracted public concerns in terms of serious influences to wild lives and a human being, such as carcinogenicity, mutagenicity, and disturbance in endocrine systems. The biological recalcitrance of the compounds is caused by the number, type, and position of the chlorine substituents as well as by their aromatic structures. In general, the carbon-halogen bonds increase the recalcitrance by increasing electronegativity of the substituent, so that the dechlorination of the compounds is focused as an important mechanism for biodegradation of chlorinated aromatics, along with the cleavage of aromatic rings. The removal of the chlorine substituents has been known as a key step for degradation of chlorinated aromatic compounds under aerobic condition. This can occur as an initial step via oxygenolytic, reductive, and hydrolytic mechanisms. The studies on the biochemistry and genetics about microbial dechlorination give us the potential informations for microbial degradation of xenobiotics contaminated in natural microcosms. Such investigations might provide biotechnological approaches to solve the environmental contamination, such as designing effective bioremediation systems using genetically engineered microorganisms.