In this paper, a shot peening was conducted to improve fatigue life by increasing resistance to hydrogen embrittlement of STS316 steel, which is widely used in hydrogen environments. First, considering the efficiency of the shot peening process, an effective Almen intensity was selected and applied to the specimen surface. Second, the specimen was hydrogen embrittled at room temperature (25°C) and high temperature (60°C) using electrochemical hydrogen charging. Third, the mechanical property tests (tensile, hardness, roughness) and 4-points rotational bending fatigue tests of the specimen were performed. All mechanical properties decreased, but the fatigue life of the shot peened specimens improved at the both temperature conditions. Ultimately, the fatigue characteristics against hydrogen embrittlement of STS316 steel, which is used in various industrial fields, are improved through an effective shot peening process, and the effect is believed to be very significant.

본 연구의 목적은 키워드 네트워크를 활용하여 삶의 질과 거주성 측면에서 국내 농촌지역의 실제 생활 환경을 분석하고 농촌 생활환경의 개선을 위한 정책적 방향성을 제시하는 것이다. 현재 우리나라의 농 촌은 고령화, 인구감소, 경제활동 저하, 기초생활서비스 부족 등의 문제가 발생하고 있다. 이를 해결하 기 위한 농촌 생활환경 개선방안의 연구가 필요하다. 따라서 본 연구에서는 삶의 질(Quality of life)과 거주성(Livability)개념을 바탕으로 이론적 측면에서 국외 연구 동향을 분석하였다. 또한 국내 농촌 생 활환경에 대한 현황을 파악하기 위해 키워드 네트워크 분석을 실시하였다. 이를 토대로 삶의 질과 거주 성 측면에서의 이론적 연구 경향 분석을 통해 실제 우리나라 농촌 생활환경에 직면한 문제점을 분석하 였다. 그 결과 국내에서 농촌 생활환경 개선을 위해 고려해야 할 사항으로 1)녹지 및 생태시설 조성, 2)지 역과 개인 및 주민 간 상호작용 개선, 3)에너지 효율을 고려한 주거공간 마련, 4)다양한 관점에서 농촌환 경을 포괄할 수 있는 목표 설정의 4가지 방안을 제안하였다. 국내 농촌의 개선 목표로 제시되고 있는 지속가능성과 더불어 농촌 회복력(Rural resilience)의 개념을 도입하면 농촌의 기능 회복에 기여할 수 있을 것이다.

Deep geological disposal is generally accepted to be the most practical approach to handling radioactive wastes. Bentonite has been considered as a buffer material in deep geological disposal repositories (DGR) for high-level radioactive wastes. Evaluating the effect of short-term bentonite alteration on EBS performance has limitations in safety assessment over thousands of years. Information on bentonite characteristics under various conditions obtained from natural systems can be used to evaluate long-term safety of bentonite buffer. The purpose of this study was to investigate mineralogical and physicochemical characteristics of bentonite in the Naah mine located in Yangnam-myeon, Gyeongju-si for a natural analogue of the bentonite barrier in DGR. A total of 15 samples were collected at regular intervals from the bentonite layer and andesitic lapilli tuff (i.e., parent rock) at the boundary with the bentonite layer. The bentonite layer is located at a depth of about 1 m below the ground surface. Each sample was separated into particles < < 75 μm and particles < 2 μm through grinding and sedimentation processes. The separated subsamples were characterized mineralogically and physiochemically using various analytic techniques. Bentonite samples have a similar SiO2/Al2O3 ratio to the parent rock and a lower (Na+K)/Si ratio than the parent rock, indicating depletion of alkali components during bentonitization. The parent rock and bentonite samples have similar mineral composition (i.e., quartz, feldspars, opal-cristobalite-tridymite and montmorillonite). Results of XRD analysis on the randomly distributed particles < 2 μm indicate that bentonite is mostly composed of Ca-montmorillonite, which is a typical dioctahedral smectite. Results of FTIR and VNIR analysis indicate that montmorillonite contained in bentonite is Al-dioctahedral montmorillonite, and Al is substituted with Mg in some octahedron units. The mineralogical and physicochemical characteristics are similar regardless of sampling location. These results suggest that bentonite potentially exposed to weathering, located near the ground surface, has hardly altered.

Gluten-free industry has experienced consistent growth with increasing the number of individuals with celiac disease. Among gluten-free products, the popularity of rice noodles has been worldwide increasing over the recent years. However, rice noodles have several processing limitations such as high cooking turbidity and long cooking time. Therefore, various ingredients have been incorporated into the formulation of rice noodles in order to improve their quality attributes. In this study, turanose which is known to be a new sugar alternative with low sweetness was applied to rice noodles and their effects were characterized in terms of thermal, rheological, and textural properties. Gluten-free rice noodles were prepared with different levels of turanose (0.5, 1.0, 1.5%, w/w) by using a twin-screw extruder. Rice flour with turanose had higher gelatinization temperature and also showed higher enthalpy values after storage at 4°C. The use of turanose also increased the pasting and mixing parameters of rice flour. In addition, the application of turanose to rice noodles affected their qualities such as texture and cooking loss. Thus, this study demonstrated that turanose could positively contribute to enhancing the qualities of gluten-free rice noodles as a new additive.

The sintering mechanisms of nanoscale copper powders have been investigated. A molecular dynamics (MD) simulation with the embedded-atom method (EAM) was employed for these simulations. The dimensional changes for initial-stage sintering such as characteristic lengths, neck growth, and neck angle were calculated to understand the densification behavior of copper nano-powders. Factors affecting sintering such as the temperature, powder size, and crystalline misalignment between adjacent powders have also been studied. These results could provide information of setting the processing cycles and material designs applicable to nano-powders. In addition, it is expected that MD simulation will be a foundation for the multi-scale modeling in sintering process.