• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.455-460
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• 2004

There have been many speculations about the presence of cosmic ray protons (CRps) in galaxy clusters over the past two decades. However, no direct evidence such as the characteristic $\gamma$-ray signature of decaying pions has been found so far. These pions would be a direct tracer of hadronic CRp interactions with the ambient thermal gas also yielding observable synchrotron and inverse Compton emission by additionally produced secondary electrons. The obvious question concerns the type of galaxy clusters most likely to yield a signal: Particularly suited sites should be cluster cooling cores due to their high gas and magnetic energy densities. We studied a nearby sample of clusters evincing cooling cores in order to place stringent limits on the cluster CRp population by using non-detections of EGRET. In this context, we examined the possibility of a hadronic origin of Coma-sized radio halos as well as radio mini-halos. Especially for mini-halos, strong clues are provided by the very plausible small amount of required CRp energy density and a matching radio profile. Introducing the hadronic minimum energy criterion, we show that the energetically favored CRp energy density is constrained to $2\%{\pm}1\%$ of the thermal energy density in Perseus. We also studied the CRp population within the cooling core region of Virgo using the TeV $\gamma$-ray detection of M 87 by HEGRA. Both the expected radial $\gamma$-ray profile and the required amount of CRp support this hadronic scenario.

• Nuclear Engineering and Technology
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• v.45 no.1
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• pp.61-66
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• 2013

Among the radioactive wastes generated from the nuclear power plant, a radioactive nuclide such as $^{129}I$ is classified as a difficult-to-measure (DTM) nuclide, owing to its low specific activity. Therefore, the establishment of an analytical procedure, including a chemical separation for $^{129}I$ as a representative DTM, becomes essential. In this report, the adsorption and recovery rate were measured by adding $^{125}I$ as a radio-isotopic tracer ($t_{1/2}$ = 60.14 d) to the simulation sample, in order to measure the activity concentration of $^{129}I$ in a pressurized-water reactor primary coolant. The optimum condition for the maximum recovery yield of iodine on the anion exchange resins (AG1 x2, 50-100 mesh, $Cl^-$ form) was found to be at pH 7. In this report, the effect of the boron content in a pressurized-water reactor primary coolant on the separation process of $^{129}I$ was examined, as was the effect of $^3H$ on the measurement of the activity of iodine. As a result, no influence of the boron content and of the simultaneous $^3H$ presence was found with activity concentrations of $^3H$ lower than 50 Bq/mL, and with a boron concentration of less than 2,000 ${\mu}g/mL$.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.104-109
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• 2010

Purpose: $[^{18}F]$Fallypride plays an effective radiotracer for the study of dopamine $D_2/D_3$ receptor occupancy, neuropsychiatric disorders and aging in humans. This tracer has the potential for clinical use, but automated labeling efficiency showed low radiochemical yields about 5~20% with relatively long labelling time of fluorine-18. In present study, we describe an improved automatic synthesis of [$^{18}F$]Fallypride using different base concentration for routine clinical use. Materials and Methods: Fully automated synthetic process of [$^{18}F$]Fallypride was perform using the TracerLab $FX_{FN}$ synthesizer under various labeling conditions and tosyl-fallypride was used as a precursor. [$^{18}F$]Fluoride was extracted with various concentration of $K_{2.2.2.}/K_2CO_3$ from $^{18}O$-enriched water trapped on the ion exchange cartridge. After azeotropic drying, the labeling reaction proceeded in $CH_3CN$ at $100^{\circ}C$ for 10 or 30 min. The reaction mixture was purified by reverse phase HPLC and collected organic solution was exchanged by tc-18 Sep-Pak for the clinically available solution. Results: The optimal labeling condition of [$^{18}F$]Fallypride in the automatic production was that 2 mg of tosyl-fallypride in acetonitrile (1 mL) was incubated at $100^{\circ}C$ for 10 min with $K_{2.2.2.}/K_2CO_3$ (11/0.8 mg). [$^{18}F$]Fallypride was obtained with high radiochemical yield about $66{\pm}1.4%$ (decay-corrected, n=28) within $51{\pm}1.2$ min including HPLC purification and solid-phase purification for the final formulation. Conclusion: [$^{18}F$]Fallypride was prepared with a significantly improved radiochemical yield with high specific activity and shorten synthetic time. In addition, this automated procedure provides the high reproducibility with no synthesis failures (n=28).

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.91-96
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• 2005

O-(3-[$^{18}$F]Fluoropropyl)-L-tyrosine (L-[$^{18}$F]FPT) was synthesized by nucleophilic radiofluorination followed by acidic hydrolysis of protective groups and evaluated with 9 L tumor bearing rat. L-[$^{18}$F]FPT is an homologue of O-(2-[$^{18}$F]fluoroethyl)-L-tyrosine (L-[$^{18}$F]FET) which recently is studied as a tracer for tumor imaging using positron emission tomography (PET). [$^{18}$F]FPT was directly prepared from the precursor of O-(3-ptoluenesulfonyloxypropyl)- N-(tert-butoxycarbonyl)-L-tyrosine methyl ester. FPT-PET image was obtained at 60 min in 9 L tumor bearing rats. The radiochemical yield of [$^{18}$F]FPT was 0-45% (decay corrected) and the radiochemical purity was more than 95% after HPLC purification. The total time elapsed for the synthesis of [$^{18}$F]FPT was 100 min from EOB (End-of-bombardment). A comparison of uptake studies between [$^{18}$F]FPT and [$^{18}$F]FET was performed. In biodistribution, [$^{18}$F]FPT showed similar pattern with [$^{18}$F]FET in various tissues, but [$^{18}$F]FPT showed low uptake in brain. Furthermore, [$^{18}$F]FPT showed higher tumor-to-brain ratio than [$^{18}$F]FET. In conclusion, [$^{18}$F]FPT seems to be more useful amino acid tracer than [$^{18}$F]FET for brain tumors imaging with PET.

• Nuclear Engineering and Technology
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• v.10 no.4
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• pp.215-222
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• 1978

Using tracer technique of $^{65}Zn$, a field experiment has been carried out to evaluate the efficiency of zinc fertilizer by rice plant grown under flooded conditions. The treatments include zinc slufate mixed throughout the soil with and without organic matter, combined urea-zinc fertilizer (N: 37.7%, Zn: 3.1%), and surface application at transplaning and two weeks after transplanting at the rate of 5kg Zn/ha respectively. Other treatments were zinc sulfate mixed throughout the soil at the rate of 10 kg and 20 kg Zn/ha respectively. Root dipping in 2 % ZnO suspension, only organic matter added, and control were also included. There was not much difference in rough grain yield between zinc levels and different application methods, but the highest yield was obtained from the treatment of the root dipping in 2% ZnO suspension. Among the 5kg Zn/ha treatments, the highest total zinc yield was observed from the zinc mixed throughout the soil. The organic matter treatment seemed to reduce the zinc fertilizer efficiency. In case of the zinc fertilizer levels, 5kg Zn/ha mixed throughout the soil showed the highest zinc fertilizer efficiency as compared with 10kg and 20kg Zn/ha treatments.

• Water for future
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• v.22 no.1
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• pp.81-90
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• 1989

A numerical simulation technique of three-dimensional finite difference model is developed to study the groundwater flow system in Dejima, an upland area which faces Kasumigaura Lake. For general perspectives of the groundwater flow system, a steady state three-dimensinal model is simulated. For the sedimentary mud formations which are found in the representative formation, three situations where the horizontal permeability is equal to 10 times and 100 times of the vertical one. The finite difference grid used in the simulation has 60$\times$50$\times$30=90,000 nodes. A converged solution with a tolerance of 0.001 meter of hydraulic head is set. Having determined the flow net by using a steady state three-dimensional model, the results for the three cases of hydraulic conductivity are compared with the results of the tracer methods (Bae and Kayane, 1987). With the aid of four representative vertical cross-sections, groundwater flow systems in the study area are assumed. The results of these are reasonally good comparable with the results of the basin yield and thd recharge-discharge distribution 8.

• Journal of the Korean Chemical Society
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• v.13 no.1
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• pp.68-74
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• 1969

Flourination of Ethyl, ${\alpha},{\beta$}-dichloro-${\beta$}-phenyl propionate, Ethyl ${\alpha},{\beta$}-dibromo ${\beta$}-phenyl propionate, Ethyl ${\alpha},{\beta$}-dichloro ${\beta$}-(p-chloro-phenyl) propionate, and dibromostyrene by potassium fluoride were investigated in presence of dimethyl formamide, diethylene glycol, and diethylene glycol monomethyl-ether. The reactivity of these organic halogen esters and hydrocarbons towards potassium fluoride was checked further by means of radioactive fluorine-18. tracer. Generally, the reaction gave monofluoride together with dehalogenated olefin. The formation of olefine was increased when the reaction was done at high reaction temperature in presence of diethylene glycol, whereas the lower reaction temperature in presence of diethyleneglycol monomethyl ether favored the formation of mono fluoride in a good yield. The procedures and methods of the identification of monofluorides were described and the feasibility of this reaction of fluorine containing ester including the F-18 labelled compounds was discussed.

• Nuclear Engineering and Technology
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• v.24 no.2
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• pp.121-129
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• 1992

Radio-tracer experiments on the Sr-90 absorption by rice and soybean from a sandy-loam soil of pH 6.35 treated with 5.2 and 31.2Bq Sr-90 per g-soil were carried out through pot cultivations. Sr-90 absorption rates of both crops increased till the mature stage when the rates were about 1.0%. Concentrations in their whole tops, however, decreased or changed little as they grew. Sr-90 concentrations in plant parts of both crops increased with the increase of those in soil. Soil-to-plant transfer coefficients of Sr-90 for rice and soybean at mature stages ranged, on the dry weight basis, from 0.07(unpolished seed) to 3.67(lean and from 0.86(seed) to 9.26(leaf), respectively. Only the unpolished rice seed showed a significant difference in the coefficient with 0.17 in 5.2Bq treatment and 0.07 in 31.2Bq treatment. Sr-90 retention rates of the upper 15cm soil after crop harvests were about 80% Sr-90 absorptions had no effect on the plant growth and yield of the crops.

• Analytical Science and Technology
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• v.13 no.6
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• pp.751-758
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• 2000

A study was carried out on the dissolution of spent PWR fuels and performed on the fuels and the separation of iodide for the quantitative analysis using SIMFUEL which has chemical composition of a simulated spent PWR fuel (burn-up; 35,000 MWd/MTU and cooling time; 10 years). To dissolve the SIMFUEL effectively and to minimize the formation of volatile iodine through dissolution process, the optimum ratio of mixed acid ($HNO_3/HCl$ 80: 20 mol%) was established and ozone gas was purged. In the separation step of iodine with $CCl_4$, $NH_2OH{\cdot}HCl$ was used for reducing ${IO_3}^-$ to $I_2$.The optimum acidity of the dissolved solution and the added of $NH_2OH{\cdot}HCl$ were 2.5 M and more than $1.5{\times}10^{-3}mole$, respectively. The recovery of iodide by ion chromatography was $82.8{\pm}4.1%$ and the total yield was corrected by gamma spectrometery using $^{131}I$ as a tracer.

• Journal of Radiation Protection and Research
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• v.41 no.3
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• pp.245-252
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• 2016

Background: Ingestion of $^{210}Po$ laden seafood accounts for a substantial amount of the effective dose of $^{210}Po$. Among seafood items, mollusks, especially domestically produced oysters and mussels, are highly enriched in $^{210}Po$ and are consumed in large quantities in Korea. Materials and Methods: Oysters and mussels around the Korean coasts were collected from major farm areas in November 2013. Samples were spiked with an aliquot of $^{209}Po$ as a yield tracer, and they were digested with $6mol{\cdot}L^{-1}$ $HNO_3$ and $H_2O_2$. The $^{210}Po$ and $^{209}Po$ were spontaneously deposited onto a silver disc in an acidic solution of $0.5mol{\cdot}L^{-1}$ HCl and measured using an alpha spectrometer. The activity concentrations of $^{210}Pb$ and $^{210}Po$ were decay corrected to the sampling date, accounting for the possible in-growth and decay of $^{210}Po$. Results and Discussion: $^{210}Po$ activity concentrations in oysters were in a range from 41.3 to $206Bq{\cdot}(kg-ww)^{-1}$ and mussels in a range from 42.9 to $46.7Bq{\cdot}(kg-ww)^{-1}$. The $^{210}Po$ activity concentration of oysters in the turbid Western coast was higher than the Southern coast. The $^{210}Po$ activity concentration of the oysters was positively correlated ($R^2=0.89$) with those of the suspended particulate matter in the surface water. The calculated annual effective dose of $^{210}Po$ from oysters and mussels consumed by the Korean population was 21-104 and $5.01-5.46{\mu}Sv{\cdot}y^{-1}$. The combined effective dose due to the consumption of oysters and mussels appears to account for about $35{\pm}19%$ of that arising from seafood consumption in the Korean population. Conclusion: The annual effective dose of $^{210}Po$ for oysters in the Korean population was found to be higher than other countries. The total annual effective dose of $^{210}Po$ due to consumption of oysters and mussels consumed in Korea was found to be $76{\pm}42{\mu}Sv{\cdot}y^{-1}$, accounting for $28{\pm}16%$ of the total effective dose of $^{210}Po$ from food in Korea.