• Nuclear Engineering and Technology
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• v.52 no.7
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• pp.1517-1523
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• 2020

The widely used medical isotope technetium-99 m (^99mTc) is a daughter of Molybdenum-99 (⁹⁹Mo), which is mainly produced using dedicated research reactors from the nuclear fission of uranium-235 (²³⁵U). ^99mTc has been used for several decades, which covers about 80% of the all the nuclear diagnostics procedures. Recently, the instability of the supply has become an important topic throughout the international radioisotope communities. The aging of major ⁹⁹Mo production reactors has also caused frequent shutdowns. It has triggered movements to establish new research reactors for ⁹⁹Mo production, as well as the development of various ⁹⁹Mo production technologies. In this context, a new research reactor project was launched in 2012 in Korea. At the same time, the development of fission-based ⁹⁹Mo production process was initiated by Korea Atomic Energy Research Institute (KAERI) in 2012 in order to be implemented by the new research reactor. The KAERI process is based on the caustic dissolution of plate-type LEU (low enriched uranium) dispersion targets, followed by the separation and purification using a series of columns. The development of proper waste treatment technologies for the gaseous, liquid, and solid radioactive wastes also took place. The first stage of this process development was completed in 2018. In this paper, the results of the hot test production of fission ⁹⁹Mo using HANARO, KAERI's 30 MW research reactor, was described.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.106-110
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• 2001

Formation of stoichiometric lithium-, nickel-, and zinc- ferrites by calcining organo-metallic precursors a temperature below 40$0^{\circ}C$ is examined using DTA/TG, and XRD techniques. It attempts to simulate th immobilization of metal ions in industrial liquid influents (waste) through the synthesis of stoichiometric spinel ferrites (SSF). Two steps of the SSF formation during thermal treatments are noted. The transformation of magnetite to ${\gamma}$ - Fe$_2$O$_3$and subsequent first formation of SSF were observed at temperatures ranging from 200 to 45$0^{\circ}C$. Th formation of cation-containing ${\gamma}$-Fe$_2$O$_3$and subsequent second formation of the ferrite occurred at temperature ranges of < 45$0^{\circ}C$ and 500 to $650^{\circ}C$, depending on the heating rate used. Then the temperature range of 200t 45$0^{\circ}C$ is critical to the performance of the technique, because a calcination at the range would lead to a complete formation of SSF, avoiding the occurrences of ${\gamma}$-Fe$_2$O$_3$and ion-containing ${\gamma}$-Fe$_2$O$_3$. If not, so $\alpha$-Fe$_2$O$_3$would occur. And annealing at temperature above $650^{\circ}C$ must be employed by which solid-state reactio of $\alpha$-Fe$_2$O$_3$with metal ions (possibly metal oxides) to form SSF can be conducted.

• Korean Journal of Environmental Agriculture
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• v.23 no.1
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• pp.22-27
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• 2004

The activated paper mill sludge was treated with WF and some additives (sodium sulfide, nickel nitrate, ethyl acetate) for methane fermentation at $35^{\circ}C$. Optmum C/N ratio was 60 out of three conditions (20, 30 and 60). The Period of 40% of methane content possibly ignition, was 2 days shorter than with non-treatment during 10 days. Nevertheless, the total amount of methane production showed the 1/8 level of control far the same period. The yield and content of methane were increased by the addition of sodium Sulfur and ethyl acetate. Sulfur was an essential factor in methane fermentation of paper mill sludge.

• Journal of Animal Environmental Science
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• v.19 no.2
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• pp.101-108
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• 2013

This study was to investigate the effect of addition levels of odor reducing contents on reducing the concentration of odorous compounds. Slurry treatments included three levels mixture of horseradish powder (HP), mushroom waste (MW) and probiotics powder (PP), and non-treatment control (n=4 each group). Levels of odorous compounds were measured from the liquid slurry incubated in room temperature ($20{\sim}25^{\circ}C$) for 2 wk in chamber whose structure is similar to slurry pit. Concentration of phenols and indoles was lower (p<0.05) in level 1, which was mixed HP 0.01%, MW 0.4% and PP 0.004% (98.69, 1.87 ppm) compared to control. Short chain fatty acid (SCFA) and branched chain fatty acid (BCFA) was lowest (p<0.05) level 1 (6,557, 1675 ppm). Taken together, lower level are effective in reducing odorous compounds in pig slurry.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.692-700
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• 1996

The objective of this study is to develop a systematic purification plant using the metabolism of aerobic microorganisms. This system is subsequently aerated and continuously removes suspended solids and settling sludges caused by aerating pressure at the bottom of a lower pipe (i.e., Continuous Removal of Suspended solids and Settling sludges, CRSS). The CRSS plants are brought out by introducing fine air bubbles into the liquid phase of a lower pipe in the bio-reactor. These plant uses aeration pipe, with multiple inlets to sweep the floor of bio-reactor tank, instead of the conventional scraper mechanisms. The principal advantage of this system is that it can continuously remove very small or light particles that settles completely within a short time. Once the particles have been floated to the surface, they can be moved into the pipe and collected in the settling tank by sequently aerated pressure. The experimental results shows that about 99.0% of the biochemical oxygen demand(BOD), 99.3% of the suspended solid(SS), 92.3% of the total nitrogen(T-N), 99.0% of the turbidity(TU), 100% of the total coliform(TC)and ammonia was respectively removed during aerobic digestion for 9 days. These result indicates that the CRS S plants are very effective for reduction and deodorization of swine wastewater contaminants, and the efflux from CRS S can either be discharged in the river or used as nutrient solution of formulation for plant growth factories. The developed CRSS plant proved to be flexible and it can simply be adapted to any type of biological waste treatment problem.roblem.

• International Journal of Highway Engineering
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• v.7 no.3 s.25
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• pp.53-62
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• 2005

Efficient snow-removing work is one of important processes of winter road management. Calcium chloride has been used as a typical deicing agent in Korea. It presents superial performance as snow deicing agents, however it has been known to give serious environmental problem and to deteriorate durability of concrete structure in road by corrosion. The environment-friendly road deicing agents made from the waste material which is liquid phase organic matter that is Ca Mg and reactant of organic acid (nitric acid and propionic acid) have been introduced by number of researchers. They indicated the calcium magnesium salt of organic acids have advantage over the calcium choride in terms of lower production unit cost by resources recycling and can solve environmental problem and durability deterioration of structures. In this study, the deicing performance of calcium magnesium salt of organic acids(CMO) is investigated based on the series of experiments including the test for heat of dissolution, freezing point, ice melting test and ice penetration test.

• Fire Science and Engineering
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• v.30 no.3
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• pp.110-116
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• 2016

The major aim of this study was to provide information on the chemical accidents that occurred in laboratories over the last 3 years. The total incidence of laboratory chemical accidents was 30 cases; 25 cases occurred at educational institutions. Most accidents (19 cases) occurred due to spills and leaks. The main cause of the accidents analyzed was worker carelessness (21 cases). Twenty-two accidents were related to hazardous chemical substances. In addition, general chemical substances as well as waste liquid contributed 26% to the incidents related to the laboratory. Among the 22 hazardous chemical substances involved in laboratory chemical accident, 67% of accident substances were accident preparedness substances.

• Applied Chemistry for Engineering
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• v.17 no.1
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• pp.111-117
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• 2006

The improvement of energy conservation mandates decrease consumption of fossil fuels and minimize negative impacts on the environment, which originates from large cooling and heating demand. The absorption heat pump technology has a large potential for energy saving in this respect. Adsorption heat pump is a means to upgrade waste heat without addition of extra thermal energy. The increase of absorbed amount is of great importance for absorption heat pump cycle. In this study, in order to improve the performance of absorber, the absorbers of two different types have been investigated using methanol-glycerine as a working fluid. The former was tangential feed of liquid phase without spiral tube in the absorber and the latter was with spiral tube in the absorber. The latter was found to be more effective in enhancing the mass and heat transfer to increase the absorption performance.

• Journal of the Korean GEO-environmental Society
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• v.6 no.3
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• pp.17-23
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• 2005

In Korea, the production of reclaimed concrete materials has been increased due to the increase in the concrete structures taken down every year. The reclaimed concrete materials have been reused as road materials. However, the studies on their mechanical and environmental properties have been very limited. The recycled rate of the materials is currently low in Korea. This paper presents the investigation of mechanical and environmental properties of the reclaimed concrete materials, as well as the comparisons with those of gravel. For the evaluation of the mechanical and environmental characteristics, following tests were conducted on both reclamed materials and gravel; liquid limit, plasticity index, CBR, sand equivalent test, abrasion test, pH test, and column leaching test. The test results showed that the reclaimed concretes satisfy the requirements for use as roadbase, subbase, and subgrade materials, except base materials. The pH of reclaimed concrete materials was less than 11 and the leaching test results satisfied the regulatory requirement of Waste Management Act in Korea. Based on the investigations, it appears that the reclaimed concrete materials are environmentally safe and applicable for use as road materials.

• Nuclear Engineering and Technology
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• v.6 no.2
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• pp.97-111
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• 1974

The adsorption mechanism of Cs-137 in low level radioactive solution by vermiculite treated with Na ion is studied in order to investigate its effective utilization for the radioactive effluent treatment. The beneficial role of Na-vermiculite is that Na ion can induce the wider c-axis spacing in which Cs ion can be sorbed in vermiculite. Cation exchange capacity and distribution coefficient of cesium seems to be influenced by the variation of c-axis spacing of vermiculite. Comparative identification and detection with the characteristic analyses of X-ray diffraction and electron diffraction patterns, diffrential thermal analysis and electron microscopy of Na-, K- and Cs-vermiculite are studied for the phemomena of Cs adsorption by vermiculite. This importance of the utilization in terms of adsorption and fixation of cesium involving vermiculite is discussed. It is found that the Na-vermiculite is valuable outside charging material for high level radioactive liquid waste storage tank of underground to protect the pollution of the underground water.