The Republic of Korea is implementing safeguards for domestic nuclear facilities through cooperation with the IAEA. But it is not to evaluate the material balance for the material unaccounted for, MUF in the bulk handling facility. Although the development of a material balance evaluation program is underway, there are no related regulations. The State Regulatory Authority, SRA is performing material balance evaluation, MBE on the facility based on the design information and material balance results of the facility. However, it is not possible to directly derive measurement uncertainty for the facility’s measurement equipment, which is an important variable of MBE. To solve this problem, it is trying to derive a method suitable for the domestic environment by investigating the some measurement uncertainty estimation methods and analyzing characteristics of them. In this study, the traditional measurement uncertainty estimation method, GUM method and GUM-S1 method were studied and the advantages and disadvantages were analyzed. Due to the problems mentioned above, the uncertainty quantification technique currently being used cannot be applied to the evaluation of the domestic material balance. Therefore, we are tying to apply them to the evaluation the domestic material balance through the above three methods or a combination of them appropriately. Through this continuing study, it is expected that it will be possible to present a plan to derive measurement uncertainty optimized for the domestic MBE environment.

The method of evaluating the forming limit of sheet metal is using the forming limit diagram(FLD), and the test method for measuring forming limit curve(FLC) is ISO standardized. On the other hand, in the case of metal bulk materials, it was confirmed that the forming limit was defined by using various predictive models based on the ductile fracture theory. However it did not show a constant forming limit (limit damage value) depending on the shape of the specimen. Therefore, a study was conducted on the derivation of the triaxial stress curve to predict the fracture of the material for various stress triaxiality, not the existing limit damage value.

덤프 트럭 데크의 경량화를 통한 연료 소비를 줄이고 에코 친화적인 설계를 위해서는 정확한 구조 분석이 필요하다. 지금까지 데크의 하중은 정수압 또는 토압 이론을 기반으로 계산되었다. 이 방법으로 데크의 하중 불균일을 계산할 수 없다. 하중 분포는 골재 입자의 크기 분포 및 상호 작용에 따라 달라진다. 이산요소법은 유한요소법보다 효과적으로 골재의 거동을 시뮬레이션할 수 있다. 본 논문에 서는 벌크 밀도와 안식각을 측정하여 주요 특성을 얻었다. 15톤 덤프 트럭 데크는 범핑, 브레이킹 및 회전 시의 운동 조건을 적용하여 얻은 하중을 사용했다. 시뮬레이션은 이산요소해석 소프트웨어인 EDEM을 사용했다. 데크의 응력 및 변형 분포는 NASTRAN에 의해 계산되었다. 측정된 값과 비교하였고, 이를 통해 DEM 시뮬레이션의 결과는 수학적 가정에 의한 결과보다 정확함을 확인하였다.

A bulk-type Ta material is fabricated using the kinetic spray process and its microstructure and physical properties are investigated. Ta powder with an angular size in the range 9-37 μm (purity 99.95%) is sprayed on a Cu plate to form a coating layer. As a result, ~7 mm-sized bulk-type high-density material capable of being used as a sputter material is fabricated. In order to assess the physical properties of the thick coating layer at different locations, the coating material is observed at three different locations (surface, center, and interface). Furthermore, a vacuum heat treatment is applied to the coating material to reduce the variation of physical properties at different locations of the coating material and improve the density. OM, Vickers hardness test, SEM, XRD, and EBSD are implemented for analyzing the microstructure and physical properties. The fabricated Ta coating material produces porosity of 0.11~0.12%, hardness of 311~327 Hv, and minor variations at different locations. In addition, a decrease in the porosity and hardness is observed at different locations upon heat treatment.

Titanium alloys are extensively used in high-temperature applications due to their excellent high strength andcorrosion resistance properties. However, titanium alloys are problematic because they tend to be extremely difficult-to-cut material. In this paper, the powder synthesis, spark plasma sintering (SPS), bulk material characteristics and machin-ability test of hybrid Ti2AlC ceramic bulk materials were systematically examined. The bulk samples mainly consistedof Ti2AlC materials with density close to theoretical value were synthesized by a SPS method. Random orientation andgood crystallization of the Ti2AlC was observed at 1100℃ for 10 min under SPS sintering conditions. Scanning electronmicroscopy results indicated a homogeneous distribution and nano-laminated structure of Ti2AlC MAX phase. The hard-ness and electrical conductivity of Ti2AlC were higher than that of Ti 6242 alloy at sintering temperature of 1000℃~1100℃. Consequently, the machinability of the hybrid Ti2AlC bulk materials is better than that of the Ti 6242 alloy formicro-EDM process of micro-hole shape workpiece.

In this study, nanocrystalline Cu-Ni bulk materials with various compositions were cold compacted by a shock compaction method using a single-stage gas gun system. Since the oxide layers on powder surface disturbs bonding between powder particles during the shock compaction process, each nanopowder was hydrogen-reduced to remove the oxide layers. X-ray peak analysis shows that hydrogen reduction successfully removed the oxide layers from the nano powders. For the shock compaction process, mixed powder samples with various compositions were prepared using a roller mixer. After the shock compaction process, the density of specimens increased up to 95% of the relative density. Longitudinal cross-sections of the shock compacted specimen demonstrates that a boundary between two powders are clearly distinguished and agglomerated powder particles remained in the compacted bulk. Internal crack tended to decrease with an increase in volumetric ratio of nano Cu powders in compacted bulk, showing that nano Cu powders has a higher coherency than nano Ni powders. On the other hand, hardness results are dominated by volume fraction of the nano Ni powder. The crystalline size of the shock compacted bulk materials was greatly reduced from the initial powder crystalline size since the shock wave severely deformed the powders.