• Journal of Radiation Protection and Research
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• v.11 no.2
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• pp.123-129
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• 1986

Using Cs-137 and Co-60 gamma-ray irradiation systems, the buildup factors for 2.9 cm thick lead absorber and the air scattering factors are determined for different beam solid angles from$2.4{\pi}{\times}10^{-3}sr\;to\;17.3{\pi}{\times}10^{-3}sr$. The corresponding buildup factors are turned out to be the values from 1.054 to 1.194 and the scattering factors to be the values from 1 to 1.064, respectively. To verify our results, calculated values using these factors and experimental values are compared. The differences between them are not more than 3. 3%.

• Nuclear Engineering and Technology
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• v.50 no.6
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• pp.886-889
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• 2018

This article presented two-staged chemical precipitation for radioactive wastewater decontamination by using chemical agents. The total amount of radioactive wastewater was $35m^3$, and main radionuclides were Cs-137, Cs-134, and Co-60. Initial radioactivity concentration of the liquid waste was 2264, 17, and 9 Bq/L for Cs-137, Cs-134 and Co-60, respectively. Potassium ferrocyanide, nickel nitrate, and ferrum nitrate were selected as chemical agents at high pH levels 8-10 according to the laboratory jar tests. After the process, radioactivity was precipitated as sludge at the bottom of the tank and decontaminated clean liquid was evaluated depending on discharge limits. By this precipitation method decontamination factors were determined as 66.5, 8.6, and 9 for Cs-137, Cs-134, and Co-60, respectively. By using the potassium ferrocyanide, about 98% of the Cs-137 was removed at pH 9. At the bottom of the tank, radioactive sludge amount from both stages was totally $0.98m^3$. It was transferred by sludge pumps to cementation unit for solidification. By chemical processing, 97.2% of volume reduction was achieved. The potassium ferrocyanide in two-staged precipitation method could be used successfully in large-scale applications for removal of Cs-137, Cs-134, and Co-60.

• Korean Journal of Environmental Agriculture
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• v.15 no.2
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• pp.198-206
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• 1996

Leaching of $^{54}Mn$, $^{60}Co$, $^{85}Sr$ and $^{137}Cs$ in paddy soil was studied using lysimeter cultures in a greenhouse. The radionuclides were applied to the water surfaces shortly before transplanting and five different times between transplanting and harvest. Fertilizer KCl and slaked lime were added simultaneously in the rate of 83kg and 200kg, respectively, per l0a following the first application after transplanting. Percolating water was sampled until two days before harvest. Concentrations of the radionuclides in percolating water decreased in the order of $^{85}Sr$ > $^{54}Mn$ > $^{60}Co$ > $^{137}Cs$ on the whole. Time taken to reach the maximum was the shortest for $^{137}Cs$(< one week) and the longest for $^{54}Mn$ and $^{85}Sr$. Six days' water dropping started 47 days after transplanting reduced the concentrations of $^{54}Mn$, $^{60}Co$, $^{85}Sr$ and $^{137}Cs$ by factors of 30-180, 3-75, 2-4 and 3-6, respectively, depending on the application time. After the significant decrease, $^{54}Mn$ concentration tended to gradually increase but $^{137}Cs$ did to the contrary Percent leaching varied 0.09-6.2% for $^{54}Mn$, 0.009-0.9% for $^{60}Co$, 1.4-14.4% for $^{85}Sr$ and 0.002-0.06% for $^{137}Cs$, with the application time. The highest leaching came from the application at 40 days after transplanting for all the radionuclides. The addition of KCl and lime increased percent leaching of the radionuclides by factors of 9, 85, 4 and 9, respectively.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.228-228
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• 1996

1, 흰쥐에서 IPM 단독투여시보다 DHP-I 저해제인 CS와의 병용투여시 AUC가 4배 이상, t$_{1}$2/가 약 3배 증가하였으며 MEPM의 경우는 AUC가 5배 이상, t$_{1}$2/가 약 1.8배 증가하였다. 2. Guinea pig에서 IPM 단독투여시보다 CS와의 병용투여시 AUC가 약 2.5배, t$_{1}$2/가 약 1.4배 증가하였으며 MEPM의 경우는 AUC, t$_{1}$2/ 모두 거의 변함이 없었다. 3. 위의 결과 흰쥐에서 IPM과 MEPM에 대한 CS의 영향이 매우 큰 것으로 나타났으며 따라서 약물동력학적인 파라메타에도 커다란 변화를 주었다. 반대로 Guinea Pig에서는 CS의 병용투여로 IPM의 AUC에만 변동을 주었을 뿐 t$_{l}$ 2/에는 크게 영향을 미치지 않았고 MEPM의 체내동태에는 거의 영향을 미치지 않았다. 4. Guinea pig에서 전체 투여량에 대한 MEPM의 요중회수율은 66.58$\pm$3.44%이었고 IPM의 경우는 7.00$\pm$0.95%이었다. 그러나 DHP-I 저해제인 CS와의 병용투여시 IPM의 요중회수율이 57.77$\pm$11.46%로 증가하여 MEPM과 거의 비슷한 양상을 나타냈다. 이는 guinea pig에서 DHP-I에 의한 IPM의 대사가 CS에 의해 차단됨을 시사하는 것이라고 사료되며 guinea pig에 존재하는 DHP-I은 MEPM보다 IPM에 대해 더 높은 친화도를 갖는 것으로 사료된다. 5. Carbapenem계 항생제의 약물동력학적 스크리닝을 위한 소동물로는 흰쥐보다도 guinea pig가 적합한 것으로 생각되나 동물종차에 의한 약물동력학적 연구 및 DHP-I의 활성에 대한 연구가 더 면밀히 이루어져야 할 것으로 생각되며 BO-2727, panipenem, biapenem 등 다른 carbapenem 항생제에 대한 광범위한 약물동력학적 연구가 진행되어 새로운 carbapenem계 항생제 개발에 따른 인체내 거동을 예측할 수 있는 치적의 실험동물모델이 확립되어야 할 것이다.

• Korean Journal of Materials Research
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• v.9 no.4
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• pp.341-344
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• 1999

We reported compositional separation(CS) into Co-enriched and Cri-enriched components inside the grains of Co-Cr based thin films prepared by rf sputtering. CS strongly depends on the sputtering conditions of substrate temperature and target composition. Tuning the microstructure of the Co-Cr films is important in order to employ the CS for high-density magnetic recording. We investigated the origin of CS from thermodynamic viewpoint. We employ a spinodal decomposition-like model to describe the origin of the CS in Co-Cr films. We consider the total free energy of the Co-Cr films as the sum of several free energies of; 1) thermodynamic mixing entropy of a binary solid solution, 2) magnetic ordering interaction(MOI) energy below the Curie temperature, and 3) excess interaction energy(XS) caused by the sputtering process as a function of temperature and composition. Those energies distorted the total free energy like the spinodal decomposition and caused the compositionally separated fine microstructure inside the grains. If the second derivative of the total free energy with respect to Cr composition becomes negative at a given substrate temperature, we may observe a metastable compositional separation inside the Co-Cr alloy films. We expect to exploit the microstructure of CS for ultra-high density magnetic recording.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.1
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• pp.19-22
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• 2003

The co-evaporated cathodes composed of A1 and CsF is adopted to enhance the electrical and the optical properties of organic light emitting diodes (OLEDs). The hole transport layer (HTL), made of 50nm thick N,N-dipheny1-N,N-bis(3-methylphenyl)-1,1-bipheny14,4-diamine (TPD), and the electron transport layer (ETL), made of 50nm thick tris(8-hydroxy-quinoline) aluminum (A1q$_3$), were deposited under the base pressure of 1.6$\times$10$^{-6}$ Torr. In depositing A1-CsF, the mass ratio of CsF is varied between 1 and 10wt%. OLEDs with co-evaporated cathodes have luminance of about 35,000cd/$m^2$, and external quantum efficiency of about 1.38%. Cs tends to diffuse into the organic layer and then re-forms Cs$^{+}$cation and free electron with the Cs-doped surface region.n.

• Journal of Radiation Protection and Research
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• v.23 no.1
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• pp.7-15
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• 1998

In order to evaluate the effectiveness of some decontamination agents against skin contamination of $^{60}Co$ and $^{137}Cs$, the experiments were carried out in this study. In the experiments, pig skin was used instead of human skin , $^{60}CoC1_2$ and $^{137}CsCl$ were used the liquid sources of skin contamination. To examine the effectiveness of decontamination agents, skin decontamination was tried using soup, EDTA, KAERICON which was developed for decontamination of radionulides on the surface of building structure, and new decontamination agents such as IOCON, TRICON, and CHARCON, which were developed in this study. The absorption of radionuclides through the skin was evaluated by the gamma-tay detection on the surface of sample skin after radionuclides were penetrated into the skin during 16 hour soiling time. The results of this absorption experiment indicated that 11.5% and 3.2% of initial amounts of $^{137}Cs$ and $^{60}Co$, respectively, were panerated into the skin. In the experiment to remove the residual radioactivity fixed on the skin, KAERICON showed the decontamination rates up to 52.1%(decontamination factor of 2.1) and IOCON showed the equivalent decontamination rate (decontamination factor 1.9) for $^{137}Cs$. However, IOCON and CHARCON showed the poor decontamination rates of less than 20%(decontamination factor of 1.2) for $^{60}Co$, and KAERICON showed the poor decontamination rate (decontamination factor 1.1) for $^{60}Co$. For TRICON, the decontamination factors were 1.6 to 1.8 for $^{137}Cs$, and 1.0 to 1.2 for $^{60}Co$, respectively.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.1
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• pp.9-17
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• 2007

In order to compare the correlation of radioactivity ratio between the radwaste streams and the primary coolant of PWR NPPs, A RCS sampling kit was installed to primary coolant system for the collection of the radionuclides during the normal operation of NPPs. RCS samples were collected from PWR type of domestic NPPs through 2004 to 2005, and pretreated with acid microwave digestion or leaching method to assay quantitatively of several interesting radionuclides. The radioactivity ratios of $^{137}Cs\;to\;^{60}Co$ in a filter cartridge and a resin cartridge were 2.3E-2 and 7.3E-1, respectively. At a same period of the reactor operating cycle, the radioactivity ratios of $^{137}Cs\;to\;^{60}Co$ were 6.3E-1 for a evaporator bottom, 6.7E-1 for a spent resin, and 5.6E-2 for a dry active waste, so that these radwaste streams were identified as having similar characteristics with the corresponding RCS samples.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.209-212
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• 2002

Main radionuclides of the soil waste stored in Korea Atomic Energy Research Institute are Co-60 and Cs-137. Moisture content of soil is 12%, pH of soil is 5.8, and content of organic matter is 2.2 %. Radioactive concentrations of the soil particle size of which is less than 0.063mm and soil in the drum surface of which is more than radiation dose rate 0.05mR/hr are higher. Meanwhile, radioactive concentration of soil in the drum surface of which is less than radiation dose rate 0.02 mR/hr are mostly lower. On using the mixing solution of ammonium sulfate and citric acid, 62% Co was removed from soil and 41% Cs was removed. Also, on using the mixing solution of ammonium nitrate and citric acid, 61% Co was removed from soil and 39% Cs was removed, and on using the mixing solution of ammonium potassium oxalate, 36% Co was removed and only 3% Cs was removed. And on using only water, removal efficiency is less than 5%.

• Journal of the Korean Chemical Society
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• v.24 no.1
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• pp.1-7
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• 1980

Solvolysis rate constants for methylchloroformate, methylthionochloroformate, methylthiolchloroformate and methyldithiochloroformate have been determined conductometrically in methanol, ethanol and ethanol-water mixtures and activation parameters have been derived. Results show that methylchloroformate solvolyzes through $S_N2$ process while methyldithiochloroformate solvolyzes by $S_N1$ process in all the solvent systems. The rate of hydrolysis decreased in the order, $CH_3S(CS)Cl>CH_3S(CO)Cl>CH_3O(CS)Cl>CH_3O(CO)Cl$ which corresponds to the order of decreasing $S_N1$ character. In methanol, $CH_3S(CS)Cl$ solvolyzed via the $S_N1$ mechanism while the others solvolyzed via the $S_N2$ process. In ethanol, however, $S_N2$ character was dominant for all the compounds, except methyldithiochloroformate, for which $S_N1$ character was still strong enough to accelerate the rate of ethanolysis. In ethanol-water mixtures, $CH_3S(CS)Cl$ and $CH_3S(CS)Cl$ solvolyzed via $S_N2$ process in ethanol-rich region while the $S_N1$ character increased greatly in water-rich region for the solvolysis of these compounds. The order of $S_N1$ character for solvolysis in water-rich region was the same as the order of hydrolysis rate.