Activated corrosion products deposited on the reactor coolant system in a nuclear power plant should be removed to reduce the radiation exposure to workers. Chemical decontamination processes using organic acids have been widely applied to remove the activated corrosion products. However, they are highly corrosive to the base metal and generate a considerable amount of ion exchange resin waste, which is hard to be treated. In order to resolve this problem, KAERI has been developed a chemical decontamination process using chelate-free inorganic acid, HyBRID (Hydrazine Based Reductive metal Ion Decontamination) process. Especially, the Cyclic SP (Sulfuric acid/Permanganate)- HyBRID process was suggested as the decontamination process for applying to the remove the double oxide layer generated on the reactor coolant system in the pressurized water reactor (PWR). During the Cyclic SP-HyBRID process, the process is continuously applied without discharging or recharging of the decontamination process solution from the primary circuit. Thus, it is necessary to include the removal processes of the decontamination reagents middle of the Cyclic SP-HyBRID process, e.g., ‘Mn removal step’ for removing the permanganate ions and ‘hydrazine decomposition step’ for decomposition of the remaining hydrazine. During these removal processes, the metal ions can also be removed from the process solution. In this study, the behaviors of metals were investigated during the Cyclic SP-HyBRID process. The concentration changes of metal ions in the process solution were analyzed using atomic absorption (AA) spectroscopy. The metal precipitates generated during the process were characterized using X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) spectroscopy. From the results of the analysis, it was observed that the metal ions dissolved in the process solution were converted into metal hydroxides and precipitated at the Mn removal process. It was confirmed by equilibrium calculation result that the OH− ions generated at the Mn removal can react with the metal ions and form the metal hydroxides. It is considered that this removal behaviors of the metals can contribute the decontamination performance.

Laser scabbling experiments were conducted with the aim of developing concrete decontamination technology. Laser scabbling system contains a 6 kW fiber laser (IPG YLS-6000, λ=1,070 nm) and optical head, which are connected with process fiber (core dia.: 600 μm, length: 20 m). Optical head consists of two lenses (f = 160 mm and 100 mm) to collimate and focus laser beam. The focused laser beam is passed through the small diameter of nozzle (throat dia.: 3 mm) to prevent the laser-produced debris into head. And then, the focused beam is directed toward concrete block as continuously diverging. The diverged laser beam was incident on the high-strength concrete with 300 mm (length) × 300 mm (height) × 80 mm (width) to induce explosive spalling on the concrete surface. The optical head was moved by X-Y-Z manipulate coupled with a computerized numerical control while scabbling. We have observed not only active spalling on the concrete surface but energetic scattering of laserproduced debris when scabbling on high-strength concretes. It indicates the need for a device capable of collecting the laser-produced debris. We newly designed and manufactured dust collector coupled with cylindrical tube to prevent scattering of laser-produced debris into ambient environment. The collecting system was evaluated by estimating the collecting efficiency for laser-produced debris while scabbling. The collecting efficiency was calculated on the basis of the information on the mass loss of concrete block after laser scabbling and the mass of collected debris in a container. The collecting efficiency was found to be over 85%.

Cutting reactor pressure vessels (RPV) into acceptable sizes for waste disposal is a key process in dismantling nuclear power plants. In the case of Kori-1, a remote oxyfuel cutting method has been developed by Doosan Heavy Industry & Construction to dismantle RPVs. Cutting radioactive material, such as RPV, generates a large number of fine and ultrafine particles incorporating radioactive isotopes. To minimize radiological exposure of dismantling workers and workplace surface contamination, understanding the characteristics of radioactive aerosols from the cutting process is crucial. However, there is a paucity of knowledge of the by-products of the cutting process. To overcome the limitations, a mock-up RPV cutting experiment was designed and established to investigate the characteristics of fine and ultrafine particles from the remote cutting process of the RPV at the Nuclear Decommissioning Center of Doosan Heavy Industry & Construction. The aerosol measurement system was composed of a cutting system, purification system, sampling system, and measurement device. The cutting system has a shielding tent and oxyfuel cutting torch and remote cutting robot arm. It was designed to prevent fine particle leakage. The shielding tent acts as a cutting chamber and is connected to the purification system. The purification system operates a pressure difference by generating an airflow which delivers aerosols from the cutting system to the purification system. The sampling system was installed at the center of the pipe which connects the shielding tent and purification system and was carefully designed to achieve isokinetic sampling for unbiased sampling. Sampled aerosols were delivered to the measurement device. A high-resolution electrical low-pressure impactor (HR-ELPI+, Dekati) is used to measure the size distribution of inhalable aerosols (Aerodynamic diameter: 6 nm to 10 μm) and to collect size classified aerosols. In this work, the mock-up reactor vessel was cut 3 times to measure the number distribution of fine and ultrafine particles and mass distribution of iron, chromium, nickel, and manganese. The number distribution of aerosols showed the bi-modal distribution; two peaks were positioned at 0.01−0.02 μm and 0.04–0.07 μm respectively. The mass distribution of metal elements showed bi-modal and trimodal distribution. Such results could be criteria for filter selection to be used in the filtration system for the cutting process and fundamental data for internal dose assessment for accidents. Future work includes the investigations relationships between the characteristics of the generated aerosols and physicochemical properties of metal elements.

Elite trees of evergreen oaks (Quercus glauca, Quercus acuta, Quercus salicina, and Quercus gilva) were selected from Jeju Island and Wando Island. Elite trees were carried out by modifying the tree selection criteria. Elite trees were selected by height, DBH, clear length, crown diameter, leaf length, and leaf depth. Regarding height, Q. acuta was the highest, and the other three tree species were similar. Clear length showed the same trend as height. In the case of Q. glauca, height showed a positive correlation with DBH, crown diameter and leaf depth. In the case of Q. acuta, positive correlations were shown with all characteristics of DBH, and correlation analysis between DBH and crown diameter, and leaf length and leaf depth also showed positive correlations. In the Pearson correlation coefficient of Q. salicina, height showed a positive correlation with DBH. In the case of Q. gilva, height showed a positive correlation with DBH (0.539). As a result of analyzing the principal components for each of the six growth characteristics, the four species were divided into two principal components with an eigenvalue of 1 or higher, and the cumulative explanatory power was 57% or more. Based on the principal component results, it was possible to confirm the relationship between growth and trait characteristics by species. Still, it was not easy to understand the relationship among each selection tree, so a cluster analysis was performed using the principal component score. Based on the distance levels 5.0 and 6.0 of the selection tree of each species, they were classified into 4-5 clusters. It is judged that the above results can be used as data for the selection of elite trees of evergreen oaks.

Background: Although rectus femoris (RF) eccentric training and static stretching (SS) have been reported effectively on lumbar flexibility, and muscle architecture, most studies are results using machines and long-term effects. Therefore, we want to investigate the effect of Reverse Nordic Hamstring Exercise (RNHE), a self-eccentric training, by immediately comparing it with SS. Objectives: To compare the RNHE and SS of RF to show the effects of lumbar flexibility, and fascicle length (FL). Design: Randomized controlled trial. Methods: A total of 30 study subjects were randomly allocated into an experimental group(Reverse Nordic Hamstring Exercise) and a control group(Static Stretching). Before and after the intervention, the subject performed fingertip to floor test (FFT) to evaluate the flexibility of the lumbar spine and measured FL through the SONON 300L (Healcerion Inc., Seoul, South Korea). Results: There was a significant effect on lumbar flexibility within both groups (P<.05), also there were clear results between the two groups (P<.05). FL showed a significant increase in RNHE (P<.05), but not in SS, and there was a no significant difference between the two groups. Conclusion: RNHE is effective in improving lumbar flexibility, and FL of RF muscle.

In the current study, lactic lactic acid bacteria (LAB) Lactobacillus plantarum and Pediococcus pentosaceus were used as a mixed additive for the production of Orchardgrass silage by ensiled method and nutritional change fermentation ability and microbial content of experimental silages. The addition of LAB to Orchardgrass during ensiling process rapidly reduced the pH of the silages than the non-inoculated silages. In addition, the lactic and acetic acid content of silage was increased by LAB strains than the non-inoculated silages whereas butyric acid content was reduced in silage treated with LAB. A microbiological study revealed that higher LAB but lower yeast counts were observed in inoculated silages compared to non-inoculated silage. Overall data suggested that the addition of LAB stains could have ability to induce the fermentation process and improve the silage quality via increasing lactic acid and decreasing undesirable microbes.

In weapon assignment studies to defend against threats such as ballistic missiles and long range artillery, threat assessment was partially lacking in analysis of various threat attributes, and considering the threat characteristics of warheads, which are difficult to judge in the early flight stages, it is very important to apply more reliable optimal solutions than approximate solution using LP model, Meta heuristics Genetic Algorithm, Tabu search and Particle swarm optimization etc. Our studies suggest Generic Rule based threat evaluation and weapon assignment algorithm in the basis of various attributes of threats. First job of studies analyzes information on Various attributes such as the type of target, Flight trajectory and flight time, range and intercept altitude of the intercept system, etc. Second job of studies propose Rule based threat evaluation and weapon assignment algorithm were applied to obtain a more reliable solution by reflection the importance of the interception system. It analyzes ballistic missiles and long-range artillery was assigned to multiple intercept system by real time threat assessment reflecting various threat information. The results of this study are provided reliable solution for Weapon Assignment problem as well as considered to be applicable to establishing a missile and long range artillery defense system.