• Journal of Radiation Protection and Research
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• v.24 no.3
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• pp.155-160
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• 1999

In the natural, there exist several kinds of radioactive isotopes. From atmospheric weapon tests and then some isotopes are naturally radioactivity above all things, nuclear power plant operation and man-made radioactive isotopes concern steadily growing in the environment. During the fission process of nuclear weapon tests and nuclear power plant operation, more than 200 radioactive isotopes are generated. Among them, $^{90}Sr$ and $^{137}Cs$ has been regarded as very important isotopes due to characteristics. In this paper, a quantitative analysis method of environment low level $^{90}Sr$ is studied. Radioactivity level of the environmental $^{90}Sr$ is very low, and it emits continuous beta spectrum, and $^{90}Sr$ exists together with $^{89}Sr$, $^{90}Y$ and other radioactive isotopes. It very difficult to make the quantitative analysis of $^{90}Sr$. For the analysis of low level radioactive strontium, enrich and chemical separation of strontium from the other radioactive isotopes are needed. For the estimation of strontium recovery ratio, so called SGAT(Strontium Gravimetric Analysis Technique) was generally used among the domestic research groups, and chemical procedures were developed appropriation for the SGAT, Recently, by using ICP(Inductively Coupled atomic Plasma emission spectrophotometer), amounts of stable atoms can be measured easily and accurately to the extend of ppm or ppb. In this paper, new chemical procedures are developed to exploits the ICP technique. New developed method has simpler chemical treatment procedures and then it gives more accurate results compared with the traditional SGAT.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.123-128
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• 2001

This study was performed to find out variation of carbonation progress of agricultural hydraulic concrete structures along the used years with using Thermo Gravimetric analysis/Differential Thermal Analysis(TG/DTA) and Indicator(phenolphthalein). In this study some conclusions such as follows were derived. Firstly, The result that the age of structures and the content of $Ca(OH)_{2}\;and\;CaCO_{3}$ in concrete have proportional relationships was found in the method of TG/DTA. This relational functions could be used to estimate remain lifetime of structures, obtaining the limits of the content of $CaCO_{3}$ in concrete which reinforcement corrosion could be occurred with breaking protection cover of alkalinity. Second, if the result of strength, voids, permeability characteristics could be combined with this relational function this may be able to be used as a new more accurate assessment technique for the quality of concrete than current usual methods. Third, environmental affect could be more superintendent for concrete carbonation than the age of agricultural hydration structures. Forth, It is difficult to estimate the used year of agricultural hydraulic concrete structures with the carbonation depth measured by indicator method. Finally, the accuracy of this relational function could be decided to be upgraded with continue analysis for more structures.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.8-16
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• 2024

Limestone (CaCO₃, calcium carbonate), which is used as a raw material in the portland cement and steel industry, emits CO₂ through decarbonation by high temperatures in the manufacturing process. To reduce CO₂ emissions by the use of raw materials like limestone, it has been proposed to replace limestone with various industrial by-products that contain CaO but less or none of the carbonated minerals, that cause CO₂ emissions. Loss of Ignition (LOI), Thermogravimetric analysis (TG), and Infrared Spectroscopy (IR) are used to quantitative the amount of CO₂ emission by using these industrial by-products, but CO₂ emissions can be either over or underestimated depending on the characteristics of by-product materials. In this study, we estimated CO₂ contents by LOI, TG, IR and DTG(Differential Thermogravimetric analysis) of calcite(CaCO₃) and samples that contain CO₂ in the form of carbonate and whose weight increases by oxidation at high temperatures. The test results showed for CaCO₃ samples, all test methods have a sufficient level of reliability. On the other hand, for the CO₂ content of the sample whose weight increases at high temperature, LOI and TG did not properly estimate the CO₂ content of the sample, and IR tended to overestimate compared to the predicted value, but the estimated result by DTG was close to the predicted valu e. From these resu lts, in the case of samples that contain less than a few percent of CO₂ and whose weight increases during the temperature that carbonate minerals decompose, estimating the CO₂ content using DTG is a more reasonable way than LOI, TG, and IR.

• Applied Chemistry for Engineering
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• v.23 no.3
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• pp.352-357
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• 2012

Techniques of thermal analyses such as DSC and TGA have been used in the study of activation energy (Ea) and frequency factor (A) depending on the particle size of RDX and HMX. Activation energy and frequency factor were calculated by Kissinger's method and Vyazovkin's method. As the particle size of RDX increased, TGA showed activation energy increased, but DSC didn't show. However, In case of HMX, as the particle size increased, both of DSC and TGA showed increase in activation energy. Moreover, Vyazovkin's method can obtain activation energy and mechanism according to decomposition of RDX and HMX.

• Journal of the Korean Applied Science and Technology
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• v.14 no.2
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• pp.115-122
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• 1997

The field of printing use to pressurization ink using screen gassamer that is called screen printing. Existing cleaning solvent using screen printing are the organic solvents including aromatic compounds carried with poisonous and stench. Besides, cleaning method of current screen printing are for the most part mixed cleaning method of dipping and polish. Using 1,1,1-TCE, CFC-113 alternative system cleaning solvent be substituted for existing cleaning solvent against screen printing ink measured the cleaning efficiency according to gravimetric analysis method and property change of gassamer according to Image Analyzer. Also, Cleaning process system carry with excellent cleaning efficiency studied which was proposed new cleaning process including ultrasonic and vibration cleaning process be substituted for existing mixed cleaning method of dipping and polish.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.6
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• pp.689-698
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• 2007

Particular attention is paid to the validity of PM-10 measurement using beta attenuation method. In this study, the inter-comparison studies were undertaken for PM-10 sampler with different measuring methods. The three beta attenuation monitoring instruments (BAM1020, FH C-14, and DIGS-150) and filter based gravitational method using High Volume Air Sampler were collocated and mass concentrations were compared from August to November, 2006. The results of the investigation show that beta attenuation monitoring instruments are comparable with gravitational method within 10% of measurement error. For specific conditions under high humidity and high concentrations, the inter-comparison results also showed a relatively good agreement and this can be explained as the effect of inlet heating of beta attenuation instrument. Subsequently, this study shows that beta attenuation monitoring instruments can be equivalently used with reasonable validity when compared gravimetric method.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.10 s.241
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• pp.1130-1138
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• 2005

A national standard system for the petroleum field has been developed to calibrate and test the oil flow meters in Korea. The operating system and the uncertainty of the system were evaluated by the peer reviewers of foreign national metrology institutes in 2002. Since the characteristics of the system might be changed by time, the uncertainty of the system is reevaluated with the consideration of the long term stability of the system. It is found that the system has a relative expanded uncertainty of 0.048 $\%$ in the range of $15\~120\;m^3/h$. According to the uncertainty budget, the uncertainties of the fluid density and the final mass measurement, which are temperature dependent, contribute about $94\%$ of the total uncertainty in the oil flow standard system

• Advances in aircraft and spacecraft science
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• v.4 no.5
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• pp.573-583
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• 2017

This paper presents a first step towards the understanding of water diffusion in RTM textile composite materials for aircraft applications and focuses on the development of experimental and numerical approaches to characterize the diffusion kinetics within the material. The method consists in making samples which are representative of the materials architecture and carrying out gravimetric tests on such samples. Analysis of results with the aid of a diffusion model reconstructing the architecture of the samples helps identifying the diffusion behaviour of the material.

• Journal of the Korean Chemical Society
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• v.6 no.2
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• pp.122-124
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• 1962

The silver halide precipitate tends to separate in curdy form of flocculated colloid when it is precipitated by direct mixing of reactant solutions. This type of precipitate has a great tendency to adsorb or occlude foreign ions in the solution.When silver halide in precipitated from homogeneous solution using the slow hydrolysis of Alkyl halide or Ally halide, the precipitate becomes dense, filterable and uniform in particle size which is very advantageous in gravimetric analysis.We found that silver halide precipitates obtained from homogeneous solution with hydrogen halide formed by the hydrolysis of alkyl halide do not give the color change with fluorescein as adsorption indicater, while silver halide precipitates obtained by direct mixing method give sharply pink color which appear to be uniformly distributed through the solution in silver ion excess.

• Journal of the Korean Applied Science and Technology
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• v.16 no.3
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• pp.237-240
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• 1999

This study showed that the optimized cleaning process using non-aqueous cleaning solvents is adaptable in the industrial field for existing 1.1.1-TCE cleaning solvents which is an ozone depleting sustance. Alternative cleaning solvent system substituted for existing cleaning solvent against non-aqueous pollutants(cutting & flux oil), was evaluated for the cleaning efficiency using gravimetric analysis method and surface change of sample by Image analyzer. The results showed that alternative solvents and process had excellent cleaning efficiency.