Protein can be provided by cultivating various microbes, which contain more than 30% protein content by cell dry weight. This study compared intracellular protein concentrations of various wild-type yeasts from different sources to select the best yeast strain with high protein concentration. Among them, Saccharomyces cerevisiae KCCM 34709, used for molasses fermentation, exhibited 4.1-fold higher protein concentration than a laboratory yeast strain, S. cerevisiae D452-2. In this study, an approach consisting of random mutagenesis coupled with the Bradford protein assay-based screening method was applied to enhance the S. cerevisiae KCCM 34709 protein content. Among 1,000 mutants, the #180 mutant strain produced 5,041±519 mg/L total amino acid in 48 h, which was 31% higher than the parental S. cerevisiae KCCM 34709 strain. These results demonstrate that the #180 mutant strain can be an attractive cell factory for animal-free protein production.

The Deep Borehole Disposal (DBD) method has various advantages, such as minimizing the use of site area and corrosion of the disposal container and improving long-term structural safety. However, it is necessary to review the problems that may occur in various technologies related to the emplacement and retrieval of the disposal container and the sealing of the borehole. Therefore, the purpose of this study is to evaluate the structural integrity of an emplacement and retrieval device (hereinafter, the disposal container connecting device) of a DBD container. The disposal connecting device was evaluated according to ANSI 14.6 and NUREG-0612 standards. The allowable stress should be less than the yield strength under the load condition of 3g. The length of the disposal container connecting device was about 2,900 mm, the diameter was 406 mm, and the weight was about 1.2 tons. In addition, 10 disposal containers weighing up to 2.2 tons were handled. The disposal container connecting device was made of stainless steel, and the maximum operating temperature was about 300°C. For structural evaluation, ABAQUS finite element analysis program was used. The analysis model was modeled only 1/2 part considering symmetry condition. The analysis model was modeled using 410,431 nodes and 344,119 solid elements. Three times load was applied to the weight of the disposal container. Axisymmetric conditions were applied to the symmetrical surface of the disposal container, and vertical restraints were applied to the upper lifting lugs. A surface-to-surface contact condition was applied to the part where the contact occurred. As a result of the analysis, the greatest stress was generated at the part supported by the clamp at the disposal container connector at 168.9 MPa. In the lugs and pins connecting the guide and the connecting device, a stress of 530.1 MPa was generated by shearing. In the bolts of the disposal container connecting device, a stress of 498MPa was generated and the safety margin was 1.73. A stress of 486.1 MPa was generated in the disposal container connecting device, and the safety margin was the smallest 1.16. As a result of the analysis, all components of the disposal container connecting device showed a safety margin of 1.16 or more at the maximum operating temperature and satisfied the allowable stress.

국내에서 개발중인 콘크리트 저장용기는 방사성 물질의 격납 건전성을 유지하기 위하여 내부에 캐니스터를 포함하고 있다. 본 논문에서는 콘크리트 저장용기 내부 캐니스터의 뚜껑 용접시, 용접시간 저감과 이에 따른 캐니스터 용접부의 구조적 건 전성을 확보하기 위한 방안으로, 정상, 비정상 및 사고조건에서 캐니스터 용접부 균열을 진전시키는 하중에 의해 발생되는 균열 깊이를 분석하여, 용접부의 최대 허용결함깊이를 평가하였다. 정상, 비정상 및 사고조건에서의 구조해석은 범용 유한 요소해석 프로그램인 ABAQUS를 사용하였으며, 허용결함깊이는 ASME B&PV Code Section XI에 따라 막응력과 조합하중 에 대해 평가하였다. 평가결과 콘크리트 저장용기의 캐니스터 용접부의 허용결함깊이는 18.75 mm로 평가되었으며, 이는 NUREG-1536에서 권고하고 있는 임계결함깊이를 만족하고 있는 것으로 나타났다.

The aim of this study was to evaluate immunopotentiating activities of β-glucan derived from Saccharomyces (S.) cerevisiae and to select new strains having possibility as an immune-enhancing substance. We examined SB20 strains derived from commercial product as a control, and extracted β-glucans from the four strains of S. cerevisiae. RAW264.7 macrophages were treated with heat-killed yeasts, β-glucans, and lipopolysaccharide (LPS). The production of nitric oxide (NO) and cytokines such as TNF-α and IL-1β were then quantified. When macrophages were induced directly by in vitro addition of β-glucan, little production of NO and IL-1β was observed. When pretreated with strong stimulants, i.e., LPS, most yeasts showed down-modulation of NO and IL-1β production. However, TNF-α secretion was triggered by β-glucans and even more increased by the mixture effect of LPS and β-glucans. In particular, S6 strain induced TNF-α secretion more than other strains. Therefore, we can conclude that the S6 strain has possibility as an immune-enhancing substance.