목적 : 대학생을 대상으로 디지털기기의 사용시간을 조사하고, 비침습적 눈물막파괴시간(NITBUT)을 측정하여 디지털기기가 눈물막에 미치는 영향을 알아보고자 하였다. 방법 : 2022년 8월부터 2개월간 충남 소개 대학에 재학 중인 대학생 55명을 대상으로 분석하였다. 눈물막 평 가는 Cornea 550을 이용하여 NITBUT를 측정하여 안구건조증과 정상안으로 구분하였다. 설문은 대상자의 일반 적 특성, 디지털기기의 사용 환경, 그리고 안구건조증 관련 자각 증상에 관해 총 14문항을 조사하였다. 결과 : 대상자들이 디지털기기를 사용하는 시간은 하루 평균 9.93±4.90시간이었다. 하루에 디지털기기를 8 시간 이상 사용하는 그룹에서 NITBUT가 안구건조증에 속한 경우는 58.5%였고, 8시간 미만의 21.4% 보다 유의 하게 높았다(p=0.029). 또한, 하루에 8시간 이상 디지털기기를 사용한 대상자들은 눈의 건조감과 안정피로를 더 크게 호소하였고, 연령, 성별, 콘택트렌즈, 굴절수술, 흡연, 수면시간을 보정한 후에 8시간 이상의 디지털기기의 사용은 안구건조증에 걸릴 확률을 5.18배 높였다(p=0.023). 디지털기기가 스마트폰인 경우는 NITBUT가 정상인 그룹에서 53.8%였고, 안구건조증 그룹에서는 69.0%였다(p>0.050). 결론 : 디지털기기의 사용시간이 8시간 이상 일 경우에는 비침습적 눈물막파괴시간이 짧아졌고, 안구건조증에 걸릴 확률이 높아짐을 확인할 수 있었다.

High-entropy alloys (HEAs) are attracting attention because of their excellent properties and functions; however, they are relatively expensive compared with commercial alloys. Therefore, various efforts have been made to reduce the cost of raw materials. In this study, MIM is attempted using coarse equiatomic CoCrFeMnNi HEA powders. The mixing ratio (powder:binder) for HEA feedstock preparation is explored using torque rheometer. The block-shaped green parts are fabricated through a metal injection molding process using feedstock. The thermal debinding conditions are explored by thermogravimetric analysis, and solvent and thermal debinding are performed. It is densified under various sintering conditions considering the melting point of the HEA. The final product, which contains a small amount of non-FCC phase, is manufactured at a sintering temperature of 1250oC.

본 연구는 국내 플라워숍에서 절화의 판매가격표시제도를 활용하는 것에 대한 소비자와 판매자의 인식 및 만족도를 알 아보고 국내 화훼시장에서의 효과적인 판매가격표시제도의 활용방안을 모색하고자 국내 소비자 237명, 판매자 32명을 대상으로 설문을 진행하였다. 소비자와 판매자 모두 절화의 가격이 절화 상품의 포장법과 함께 가장 높은 구매 결정 요인 으로 나타났다. 플라워숍의 절화 판매가격표시제도 활용 장점 에 대해 소비자가 판매자보다 높게 인식하고 있었으며, 소비 자와 판매자 모두 판매가격표시제도를 활용함으로써 소비자 의 합리적인 절화 소비 및 절화 가격 신뢰에 가장 큰 도움을 준다고 응답하였다. 소비자는 절화 판매가격표시제도에 대한 불편한 점이 모두 보통(3.00) 이하로 나온 것에 비해, 판매자 의 경우 매번 바뀌는 가격(4.25) 및 가격 표기 기준의 애매함 (3.78), 가격 표기의 번거로움(3.69)을 불편한 요인으로 인식 하였다. 효과적인 판매가격표시제도 방법에 대한 설문에서 소 비자는 한 송이, 한 단 보다는 3~4줄기의 한 묶음씩 판매를 선호하였고, 판매자는 판매 단위에 따른 선호 차이가 없었다. 가격 표시 방법에는 소비자와 판매자 모두 화병에 가격을 표 시하는 것을 가장 선호하였다. 전반적인 절화 판매가격표시제 도에 대하여 소비자들은 판매자들이 기대하는 이상으로 만족 도가 높았으며(P<0.001), 특히 절화 품질(3.75)보다도 절화 가격(3.97)에 대한 만족도가 더 높아지는 것으로 나타났다. 이 를 통해, 절화 판매가격표시제도가 활성화된다면 소비자들의 절화 가격에 대한 신뢰도와 만족도를 높여줄 것이며 국내 화 훼산업 활성화에 도움이 될 것으로 판단한다.

The analysis of uranium migration is crucial for the accurate safety assessment of high-level radioactive waste (HLW) repository. Previous studies showed that the migration of the uranium can be affected by various physical and chemical processes, such as groundwater flow, heat transfer, sorption/ desorption and, precipitation/dissolution. Therefore, a coupled Thermal-Hydrological-Chemical (THC) model is required to accurately simulate the uranium migration near the HLW repository. In this study, COMSOL-PHREEQC coupled model was used to simulate the uranium migration. In the model, groundwater flow, heat transfer, and non-reactive solute transport were calculated by COMSOL, and geo-chemical reaction was calculated by PHREEQC. Sorption was primarily considered as geo-chemical reaction in the model, using the concept of two-site protolysis nonelctrostatic surface complexation and cation exchange (2 SP NE SC/CE). A modified operator splitting method was used to couple the results of COMSOL and PHREEQC. Three benchmarks were done to assess the accuracy of the model: 1) 1D transport and cation exchange model, 2) cesium transport in the column experiment done by Steefel et al. (2002), and 3) the batch sorption experiment done by Fernandes et al. (2012), and Bradbury and Baeyens (2009). Three benchmark results showed reliable matching with results from the previous studies. After the validation, uranium 1D transport simulation on arbitrary porewater condition was conducted. From the results, the evolution of the uranium front with sequentially saturating sites was observed. Due to the limitation of operator splitting method, time step effect was observed, which caused the uranium to sorbed at further sites then it should. For further study, 3 main tasks were proposed. First, precipitation/ dissolution will be added to the reaction part. Second, multiphase flow will be considered instead of single phase Darcy flow. Last, the effect of redox potential will be considered.

The design of the high-level radioactive waste (HLW) repository is made for isolating the HLW from the groundwater system by using artificial and natural barriers. Granite is usually considered to be a great natural barrier for the HLW repository in various countries including Sweden, Canada, and Korea due to its low hydraulic permeability. However, many fractures that can act as conduits for groundwater and radionuclides exist in granite. Furthermore, the decay heat generated by the HLW can induce groundwater acceleration through the fracture. Since the direction, magnitude, and lasting time of the heat-induced groundwater flow can be differed depending on the fracture geometry, the effect of fracture geometry on the groundwater flow around the repository should be carefully analyzed. In this study, groundwater models were conducted with various fracture geometries to quantify the effect of various properties of fractures (or fracture networks) on the heat-induced groundwater flow. In all models, the pressure around the repository only lasted for a short period after it peaked at 0.1 years. In contrast, the temperature lasted for 10,000 years after the disposal inducing the convective groundwater flow. Single fracture models with different orientations were conducted to evaluate the variations in groundwater velocities around the repository depending on the fracture slope. According to the results, the groundwater velocity on the fracture was the fastest when the regional groundwater flow direction and the fracture direction coincided. In double fracture models, various inclined fractures were added to the horizontal fracture. Due to the intersecting, the groundwater flow velocity showed a discontinuous change at the intersecting point. Lastly, the discrete fracture network models were conducted with different fracture densities, length distributions, and orientations. According to the modeling results, the groundwater flow was significantly accelerated when the fracture network density increased, or the average fracture length increased. However, the effect of the fracture orientation was not significant compared to the other two network properties.