Large amounts of concrete, metal, soil, and other radioactive waste are generated not only from nuclear power plants operating in Korea but also from nuclear power plant decommissioning. If it is confirmed through measurement of residual radioactivity that the concentration is below the allowable clearance level, they can be managed as general or industrial waste in accordance with the Nuclear Safety Act. The Korea Radioactive Waste Agency predicts that very low-level radioactive waste will be generated the most, at about 67.1%. If waste below clearance level among very low-level radioactive waste can be evaluated and reduced, a lot of costs can be saved. Among radioactive wastes, metal wastes in particular have various sizes, shapes, and densities. If radioactivity is measured without properly considering this, a large error occurs in the measured value even if the radioactivity value is the same. This requires a conservative measurement method using density correction taking into account the self-absorption effect. For conservative measurements, it is essential to compare measured values with calculated values using MCNP6 (Monte Carlo N-Particle). You must enter the geometry of the measurement environment and derive calculated values using F8 Tally. Clearance level of radioactive waste is determined through the above method. In addition, sufficient MDA (Minimum Detectable Activity) must be secured to determine clearance level by using NaI(Tl), plastic scintillator configuration, and lead shielding. Nuclide analysis is performed using a NaI(Tl) scintillator and the total gamma radioactivity is evaluated using a highly efficient plastic scintillator.

전자상거래를 이용한 해외직구는 가격과 품질을 우선시하고 합리적으로 물품을 구매하는 소비자의 인식변화, 모바일을 포함한 인터넷의 확산, 국제배송의 신속화, 온라인 쇼핑몰 운영자의 적극적인 마케팅과 결제방법의 편리성 등으로 인해 2011년부터 2017년까지 매년 평균 40% 이상 증가하고 있다. 해외직구물품은 목록통관을 원칙으로 하나, 밀수․관세탈루 방지와 미화 150불 이상에 해당하는 경우에는 목록통관을 배제하고 일반통관절차를 적용하고 있다. 그러나 일반통관절차는 기업이 수입하는 물품에 적용되는 절차이므로 개인이 수입하는 해외직구물품에 적용하는 것은 적합하지 않다. 따라서 본 연구는 간이통관이 배제되는 해외직구물품에 대한 관세 등의 납세신고 방법 개선, 물품신고시 전자 상거래에 적합하도록 신고항목 축소, 그리고 서류보관 의무 면제 등의 방안을 제시하였다.

An interference fit is a fastening between two parts which is achieved by friction after the parts are pushed together, rather than by any other means of fastening. A fit is depending on which part has its size controlled to determine the fit. To select an amount of interference see KS standard tables for class from light to heavy drive fits. The aim of this paper is to find the optimal gap under the interference fit with lowest contact pressure to the two cylinders. To accurately determine the amount of interference clearance, must consider the fluctuation of the response parameters such as contact pressure, displacements and stresses. The response of the cylinder system is modelled with the probabilistic finite element method using the Monte Carlo simulation. The probabilistic design is carried out using ANSYS probabilistic design software. And then the optimal design of the interference gap is sequentially solved to find the solution. The practical optimal design is proposed for the design of the interference fit system. The numerical results are obtained where the displacements and stresses treated as constraints.

ASCE 4 requires that a hard stop be built around the seismic isolation system in nuclear power plants. In order to maintain the function of the isolation system, this hard stop is required to have clearance-to-stop, which should be no less than the 90th-percentile displacements for 150% Design Basis Earthquake (DBE) shaking. Huang et al. calculated clearance-to-stop by using a Latin Hypercube Sampling technique, without considering the rocking behavior of the isolated structure. This paper investigates the effects on estimation of clearance-to-stop due to 1) rocking behavior of the isolated structure and 2) sampling technique for considering the uncertainties of isolation system. This paper explains the simplified analysis model to consider the rocking behavior of the isolated structure, and the input earthquakes recorded at Diablo Canyon in the western United States. In order to more accurately approximate the distribution tail of the horizontal displacement in the isolated structure, a modified Latin Hypercube Sampling technique is proposed, and then this technique was applied to consider the uncertainty of the isolation system. Through the use of this technique, it was found that rocking behavior has no significant effect on horizontal displacement (and thus clearance-to-stop) of the isolated structure, and the modified Latin Hypercube Sampling technique more accurately approximates the distribution tail of the horizontal displacement than the existing Latin Hypercube Sampling technique.