In this study, an experiment was conducted in order to determine what cryopreservatives (CPVs) were more effective in supporting the motility and viability of sperm from experimental animals. The sperm of mice, rats, beagle dogs, and rabbits were frozen using different CPVs, including DMSO, TYB, and Sperm CryoProtec. The results from freezing the sperm of each laboratory animal in Sperm CryoProtec showed a high level of sperm motility and viability in sperm samples from mice, rats, and beagle dogs melted at the end of the first week. For rabbits, a high level of motility was observed in sperm thawed during the first week, whereas a high level of viability was observed in sperm thawed during the second week. The results of analysis of sperm motility and viability using different CPVs according to laboratory animals showed a significantly higher level of sperm motility (26.28%) and viability (36.20%) for mice in Sperm CryoProtec and the lowest levels of motility and viability were observed in DMSO (p < 0.05). Significantly higher levels of motility (27.94%) and viability (37.94%) were observed for rats in Sperm CryoProtec compared with TYB, which showed the lowest levels of motility and viability (p < 0.05). The study findings described above suggest that the selection of appropriate cryopreservatives is required for each experimental animal. This is because there are differences in the levels of sperm motility and viability of experimental animals depending on the CPVs that are typically used for freezing human sperm, including Sperm CryoProtec and TYB.

As Korea has recently become a multicultural society, English teachers acknowledge the need to address anti-racism in the classroom. However, how to raise students’ racial awareness and ways to incorporate racial issues into English language instruction have not been sufficiently studied in the Korean teacher education context. The aims of this study were to provide pre-service English teachers with a guide to implementing antiracist pedagogy in their language teaching and assessing its impact on their racial literacy development and to examine how pre-service English teachers’ racial literacy can be developed through multiple self-reflective practices and microteaching experiences in their teacher education programs. This paper first introduces an anti-racist curriculum for pre-service English teachers intended to raise their multicultural awareness, and then provides multiple educational resources and teaching strategies to help them become culturally responsive language teachers. The paper concludes with some pedagogical implications regarding the necessity of including culturally responsive teaching in teacher education programs.

최근 국제해사기구의 해양환경오염규제가 강화되어 오고 있다. 선박의 에너지 효율지수는 선박의 설계관점에서 매우 중요 한 지표이다. 더욱이 새롭게 건조되는 선박은 물론 기존 운항 선박에도 에너지 효율지수를 만족하도록 강화하고 있다. 이에 따라 운항 되고 있는 기존선박의 에너지 효율지수를 높이기 위해 선수 벌브개조, 운항 중 트림 최적화, 에너지 절감장치등 다양한 방법이 적용되 고 있다. 본 연구에서는 전산 유체역학을 이용하여 다양한 선수/선미 트림조건에서 선박의 저항성능을 계산하고 분석하였다. 이를 바 탕으로 최적화 된 트림조건에서 선박의 저항성능을 더욱 개선하기 위해 선수 벌브의 형상을 재설계하였다. 그 결과 정수 중에서 개선 된 벌브 형상을 적용한 경우, 유효마력이 약 5% 향상되는 것을 확인하였으며, 향후 파도 중에서 재설계된 벌브형상이 저항성능에 미치 는 영향을 조사할 예정이다.

In 2018, media reports raised issues related to radon released from building materials used as finishing materials in apartment houses. Accordingly, related ministries recommended not to use materials with a radiation index value exceeding 1. In order to calculate the radioactivity index, not only 226Ra producing radon (222Rn) but also 232Th and 40K radioactivity concentrations are required. To determine the concentration of the radionuclide, 40K is measured by a single gamma ray of 1,460.8 keV. And the 228Ac used to measure 232Th mainly utilizes gamma rays of 911.2 keV. However, 228Ac does not appear as a single peak unlike 40K, and appears as multiple peaks at various energies. Among them, gamma rays are emitted at a intensity of 0.83% at 1,459.2 keV, which is likely to interfere with 40K. Therefore, what is actually measured at 1,460.8 keV is theoretically a compound peak of 40K and 228Ac. Because the probability of emission at 1,459.2 keV (0.83%) is low, a low concentration of 232Th will result in little 40K radioactivity error. However, samples containing a high concentration of 232Th overestimate the 40K radioactive concentration, so correction is required. In this study, the IAEA standard substance (IAEA-RGTh-1) ontaining 232Th of actual high concentration was analyzed, and the results of the analysis without correction of 40K were compared and verified. As the 40K correction method, the 911.2 keV gamma-ray of 228Ac was used as the reference peak to separate the peak of 228Ac (1,459.2 keV) from the 40K (1,460.8 keV) mixed peaks. And, the coefficient value obtained by subtracting the peak of 228Ac (1,459.2 keV) from the 40K (1,460.8 keV) mixed peak was set to a pure peak of 40K and the radioactivity concentration was calculated therefrom. As a result of calculating the IAEA-RGTh-1 reference material without correction, it was confirmed that the 40K value was overestimated by about 38 times. If a measurement beyond the MDA of 40K is generated by 228Ac radioactivity because the 40K correction constant is not applied, there is an error in determining that there is 40K radioactivity. However, even if 40K radioactivity is overestimated due to the high concentration of 232Th, the degree to which this effect contributes to the radioactivity index is very small. However, as an analyst, 40K radioactivity correction should be made for more accurate analysis.

Considering the Fukushima nuclear accident and the marine discharge plan of contaminated (or treated) water, it is necessary a seafood monitoring system for radioactive material screening. Currently, radioactivity tests in seafood are conducting in Korea. Although current method using a HPGe detector can provide very low uncertainty in determining radioactivity, there is a limitation in that rapid inspection cannot be performed because of a time-consuming pretreatment process as well as long measurement time (typically 10,000 s). To overcome this limitation, we are developing an insitu inspection device, a kind of screening system, which can monitor the radioactivity in seafood in a near real-time basis. In this study, the actual seafood with a check source was measured to verify the reliability of the Monte Carlo simulation model. The detector used in the experiment was a 5-cm-thick polyvinyl toluene (PVT) plastic scintillator with a 0.5-cm-thick lead shield for background reduction. A Cs-137 check source was placed within seafood. The seafood used in the experiment was fishcake, raw oyster, and dried laver, which is the representative seafood of fish, shellfish, and seaweed. These three seafood products of the same size and shape as the manufacturing process were used to predict the performance realistically. We compared the energy spectrum of the Cs-137 check source obtained from measurements and simulations. The region of interest (ROI) around the Compton edge was set to reduce the influence of the background and electronic noise. The results showed that the measured and simulated spectrum were in good agreement.

Radioactive waste generated in large quantities from NPP decommissioning has various physicochemical and radiological characteristics, and therefore treatment technologies suitable for those characteristics should be developed. Radioactively contaminated concrete waste is one of major decommissioning wastes. The disposal cost of radioactive concrete waste is considerable portion for the total budget of NPP decommissioning. In this study, we developed an integrated technology with thermomechanical and chemical methods for volume reduction of concrete waste and stabilization of secondary waste. The unit devices for the treatment process were also studied at bench-scale tests. The volume of radioactive concrete waste was effectively reduced by separating clean aggregate from the concrete. The separated aggregate satisfied the clearance criteria in the test using radionuclides. The treatment of secondary waste from the chemical separation step was optimally designed, and the stabilization method was found for the waste form to meet the final disposal criteria in the repository site. The final volume reduction rates of 56.4~75.4% were possible according to the application scenario of our processes under simulated conditions. The commercial-scale system designs for the thermomechanical and chemical processes were completed. Also, it was found that the disposal cost for the contaminated concrete waste at domestic NPP could be reduced by more than 20 billion won per each unit. Therefore, it is expected that the application of this technology will improve the utilization of the radioactive waste disposal space and significantly reduce the waste disposal cost.

Radiological characterization is important in decommissioning and dismantling of nuclear facilities, in order to assess the radioactivity concentration, classify the wastes, and secure workers’ safety. The Some components such as Reactor Pressure Vessel (RPV) in nuclear facilities has dose rate higher than Sv/hr, thus in-situ gamma spectroscopy systems suffer from a very high count rate which causes energy resolution degradation, photo-peak shift, and count loss by pile-up and dead-time. The system must be operated in a very high count rate, in order to measure spectra precisely and to quantify radionuclide contents. In order to apply in-situ measurement in high radiation dose rate environment, the sensor, front-end electronics, and data acquisition (DAQ) should be carefully selected and designed as well as precise design of collimators and radiation shield. In this paper, the components of the detector system were selected and performance was evaluated in a high count rate before design the collimator and shield. A LaBr3 coupled with a PMT having short decay time constant (16 nsec) was selected for high count rate application, and two different amplifiers (a conventional charge sensitive preamplifier with 50 usec decay time constant, and wide-band voltage amplifier) were tested. As DAQs, DT5781 (14 bit, 100 MS/s, CAEN) of Pulse Height Analysis (PHA) which is conventionally used signal processing method in the gamma spectroscopy, and DT5730 (14 bit, 500MS/s, CAEN) of Pulse Shape Discrimination (PSD) which is similar to Charge to Digital Convertor (QDC) were used. The number of photons incident to the detector was varied by changing the detector-source distance with Certificate Radiation Material (CRM), and compared to the output count rate. The count rate capability, and energy resolution with different amplifier and DAQ was evaluated. Additionally, the performance of DAQs in extremely high count rate was evaluated with signal data generated by the emulator which can simulate the detector signal waveforms fed into the DAQ based on the measured spectrum.

The safe, efficient and cost-effective decommissioning and dismantling of radioactive facilities requires the accurate characterization of the radionuclide activities and dose rate environment. And it is critical across many nuclear industries to identify and locate sources of radiation accurately and quickly. One of the more challenging aspects of dealing with radiation is that you cannot see it directly, which can result in potential exposure when working in those environments. Generally, semiconductor detectors have better energy resolution than scintillation detectors, but the maximum achievable count rates are limited by long pulse signals. Whereas some high pure germanium detectors have been developed to operate at high count rates, and these HPGe detectors could obtain gamma-ray spectra at high count rates exceeding 1 Mcps. However, HPGe detectors require cooling devices to reduce the leak currents, which becomes disadvantageous when developing portable radiation detectors. Furthermore, chemicalcompound semiconductor detectors made of cadmium telluride and cadmium zinc telluride are popular, because they have good energy resolution and are available at room temperature. However, CdTe and CZT detectors develop irradiation-induced defects under intense gamma-ray fields. In this Review, we start with the fundamentals of gamma rays detection and review the recent developments in scintillators gamma-ray detectors. The key factors affecting the detector performance are summarized. We also give an outlook on the field, with emphasis on the challenges to be overcome.