This study investigated rice production status, rice consumption characteristics, and rice import and export trends in sub-Saharan Africa for researchers and policy makers on rice production in Africa and to suggest key strategy to improve rice self-sufficiency in Africa. In recent years, sub-Saharan Africa has seen an increasing number of food security conflicts because of climate change. The ultimate solution is to increase their food productivity and self-sufficiency in their countries. Rice is very important for poverty reduction in Africa because of its availability and affordability, making it accessible to the poor in Africa as a staple food. The total area of rice production in sub-Saharan Africa has nearly doubled from 7 million ha in 2000 to 13 million ha in 2020, and rice demand is also on the rise. However, the climate change and extreme weather events have led to greater variability in rice productivity, and international rice prices have increased continuously, making it increasingly difficult to improve Africa's rice self-sufficiency. In order to increase rice production and improve self-sufficiency in Africa, there are many challenges, such as irrigation facilities, improving soil quality, and supplying pesticides and fertilizers, but the most important is to develop and disseminate new rice varieties suitable for the African region. This will require not only breeding appropriate varieties for Africa's climate and soil, but also selecting proper varieties that meet the preferences of Africans. Additionally, an infrastructure system from production, cultivation, harvesting and storage to processing for the appropriate rice varieties should be aligned at the same time.

본 연구는 스마트 자율운항선박(Maritime Autonomous Surface Ship, MASS) 기술 개발 및 실증을 위한 산학 과제로서 목포해양 대학교와 삼성중공업이 함께 참여한 연구가 안전하게 실시되어 질수 있도록 안전관리 절차서를 개발하였다. 본 연구에서는 국내 및 국 제해사기구(International Maritime Organization, IMO)의 관련 가이드라인 및 해사 관련법 검토를 거쳐 안전관리 절차서를 개발하였다. 안전관리 절차서는 자율운항선박의 관련 해당 당국과 이해관계자들이 시스템 및 기반 시설에서 시험의 안전 및 환경 보호와 관련하여 적절하게 실시하기 위하여 국제해사기구에서 제시한 자율운항선박 시험을 위한 지침(MSC.1/Circ.1604, Annex : Interim guidelines for MASS trials)의 의거하여 개발 하였다. 개발된 안전관리 절차서는 당직체제로 운항 중인 선박에 항해보조기기로 탑재한 자율운항요소기술을 적용한 시스템의 해상 실증 시험을 위하여, 대한민국 연안의 해양환경보호와 항행 안전을 준수하면서, 관련 시스템의 시험이 안전하고 안정적으로 수행할 수 있도록 개발되었다.

A shake table test is conducted for the three-story reinforced concrete building structure using 0.28 g, 0.5 g, 0.75 g, and 1.0 g of seismic input motions based on the Gyeongju earthquake. Computational efforts are made in parallel to explore the mechanical details in the structure. For engineering practice, the elastic modulus of concrete and rebar in the dynamic analysis is reduced to 38% and 50%, respectively, to calibrate the structure's natural frequencies. The engineering approach to the reduced modulus of elasticity is believed to be due to the inability to specify the flexibility of the actual boundary conditions. This aspect may lead to disadvantages of nonlinear dynamic analysis that can distort local stress and strain relationships. The initial elastic modulus can be applied directly without the so-called engineering adjustment with infinite element models with spring and spring-dashpot boundary conditions. This has the advantage of imposing the system flexibility of the structure on the sub-boundary conditions of springs and damping devices to control its sensitivity in a serial arrangement. This can reflect the flexibility of realistic boundary conditions and the effects of system damping (such as the gap between a concrete footing and shake table, loosening of steel anchors, etc.) in scalar quantities. However, these spring and dashpot coefficients can only be coordinated based on experimental results, making it challenging to select the coefficients in-prior to perform an experimental test.

초음파 탐상은 다양한 콘크리트 구조물의 비파괴검사에서 활용된다. 본 연구에서는 골재형상을 고려한 골재-모르타르 모델 생성과 초음파 전파 해석을 수행하였다. 실제 골재형상을 반영하기 위해 이미지처리를 통한 골재-모르타르 단면으로부터 모르타르와 골재 영역을 파악하고, 영역 경계형상을 보존하면서 격자를 생성하는 기법을 개발하였다. 개발된 기법에서는 모든 격자가 4각형으로 생성된다. 골재-모르타르 모델을 통해 초음파 전파 해석을 수행하였고 모델을 반무한체로 간주하기 위해 CALM 기반 경계흡수 조건을 적용하였다. 골재 및 결함을 포함한 이미지로부터 격자를 생성한 뒤, 결함 영역에 포함된 격자를 제거하여 공극결함을 모사하였다. 본격적인 결함탐지 전 선행 해석을 통해 모델 동특성을 고려한 적절한 가진 주파수를 결정 및 가진 신호형상을 설계하였다. 이후 case 별 초음파 전파 해석을 통해 신호를 획득하고 신호 에너지 맵핑 작업을 통해 내부 결함을 가시화 하였다. 가시화 결과, 골재에 의한 다수 반사 및 산란현상이 관찰되지만 결함부에서 신호 에너지는 가장 높게 나타났으며 모든 해석 case에서 결함위치 추정이 가능하였다. 또한 균열의 경우 형상파악도 가능하였다.

The purpose of this study is to investigate the distribution patterns of displacement and acceleration fields in a nonlinear soil ground based on the interaction of high-speed train, wheel, rail, and ground. For this purpose, a high-speed train in motion was modeled as the actual wheel, and the vertical contact of wheel and rail and the lateral contact, caused by meandering motion, were simulated; this simulation was based on the moving mass analysis. The soil ground part was given the nonlinear behavior of the upper ground part by using the modified the Drucker– Prager model, and the changes in displacement and acceleration were compared with the behavior of the elastic and inelastic grounds. Using this analysis, the displacement and acceleration ranges close to the actual ground behavior were addressed. Additionally, the von-Mises stress and equivalent plastic strain at the ground were examined. Further, the equivalent plastic and total volumetric strains at each failure surface were examined. The variation in stresses, such as vertical stress, transverse pressure, and longitudinal restraint pressure of wheel-rail contact, with the time history was investigated using moving mass. In the case of nonlinear ground model, the displacement difference obtained based on the train travel is not large when compared to that of the elastic ground model, while the acceleration is caused to generate a large decrease.

본 연구는 2016년부터 2019년까지 3년에 걸쳐 수행 된 파라과이 KOPIA 센터의 참깨 시범마을 사업의 경영성과와 투자타당성을 분석하기 위한 목적으로 수행되었다. 시범사업 참여농가는 1,172천~2,928천Gs/ha의 수익이 증가하는 것으로 나타났으며, 가구 기준으로 산출할 경우 연간 760$ 이상의 소득 증가가 발생하는 것으로 분석되었다. 시범사업 투자의 타당성에 대한 평가지표로 활용된 B/C Ratio는 1.52로 분석되어 경제적 타당성이 있는 것으로 평가되었다. 시범사업에 참여한 농가들의 만족도를 7점 척도로 분석한 결과 시범사업의 전반적인 만족도, 소득증가에 대한 만족도, 수량증가에 대한 만족도 모든 항목에 대해서 만족함, 매우 만족함에 응답하였다. 계속 참여의향 역시 매우 높은 것으로 나타났으며, 종자의 균일성에 대한 만족도가 6.9점으로 가장 높았다. 성공적으로 평가되는 파라과이 KOPIA센터의 참깨 시범마을 사업의 성공요인은 첫째, 적합품목의 선택, 둘째, 현지 적응 신품종의 선발 및 보급, 셋째, 수동파종기, 배무식 분무기, 공동경운을 도입하여 생산성을 향상하고, 노동력을 절감, 넷째, 적정시비량, 윤작체계, 친환경 엽면시비 등의 재배교육을 통해 농약과 비료비는 절감하고, 수확량 증가와 품질향상을 도모한 것 등이다. 특히, 수익성이 떨어지고 있는 목화의 대체품목이며, 생산 증가에도 가격하락 위험이 적은 수출품목인 참깨를 선발한 부분과, 단기간에 이루어지기 어려운 현지적합 품종을 선발했다는 점, 수동파종기와 배무식 분무기, 녹비작물, 지렁이액비 등 저소득 농업인이 지속적으로 수용 가능한 기술이 보급되었다는 점을 높이 평가할 수 있다.

The objectives of this study were the development of a synthesis technique for highly active nanosized ITO powder and the understanding of the reaction mechanisms of the ITO precursors. The precipitation and agglomeration phenomena in ITO and precursors are very sensitive to reaction temperature, pH, and coexisting ion species. Excessive ion and ions had a negative effect an synthesizing highly active powders. However, with a relevant stabilizing treatment the shape and size of ITO and precursors could be controlled and high density sintered products of ITO were obtained. By applying the reprecipitation process (or stabilization technique), highly active ITO and powders were synthesized. Sintering these powders at for 5 hours produced 97% dense ITO bodies.

The effects of fillers on the mechanical and thermal properties of glass/novolac composites have been studied. The matrix polymer and reinforcement were novolac type phenolic resin and milled glass fiber, respectively. Three different fillers, such as calcium carbonate, aluminum oxide, and wood powder were used for glass fiber reinforced plastic(GFRP) manufacture. Gravity, moisture content, tensile and flexural strength were measured to analyze the mechanical properties of GFRP and the final composites was burned in the electronic furnace at 1000℃ to confirm thermal properties GFRP containing aluminium oxide shows the highest thermal stability with 32% of weight loss at 1000℃ for one hour. GFRP containing calcium carbonate shows the maximum flexural strength (146 MPa), but that containing wood powder dose the highest tensile strength (65 MPa). Conclusively, we found that the characteristics of final composites strongly depend on several factors, such as types of materials, contents and chemical affinity of fillers. Therefore, it is very important to set up the combination of fillers for GFRP manufacturing to improve both mechanical and thermal properties at the same time.