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AI 합금의 원소가 용융산화에 미치는 영향 -lll. 오원계 합금의 산화거동-
하용수,김철수,강정윤,김일수,조창현,Ha, Yong-Soo,Kim, Chul-Soo,Kang, Chung-Yun,Kim, Il-Soo,Cho, Chang-Hyun 한국재료학회 1998 한국재료학회지 Vol.8 No.8
오원계 AI-합금의 용융산화에 의한 $AI_2O_3$ 복합재료의 형성속도와 미세구조에 대하여 연구하였다. AI-1Mg-3Si-3Zn 합금과 AI-1Mg-3Si-5Zn합금에 Cu, Ni 각각을 1% 무게비로 첨가하였다. 각 오원계 합금은 1373K, 1473K에서 최대 20시간 동안 산화시켰으며, 산화속도는 무게증가 측정을 통하여 조사하였다. 산화층의거시적 형상과 미세구조를 광학현미경으로 관찰하였다. AI-1Mg-3Si-5Zn-1Cu 합금이 가장 우수한 산화거동을 보였으나, 산화층이 불균일하였다. 합금위에 $SiO_2$를 도포하였더니 산화속도가 증진되었으며, 균일하고 조직이 친밀한 산화층이 얻어졌다. The following work examines the growth rate and microstructure of the $AI_2O_3$-composite formation by melt oxdation of pentad AI-alloys. The I weight % of each metal elements Cu and Ni were added to AI-IMg-3Si-3Zn and AI-IMg- 3Si-5Zn alloys. The diffenent pentad AI-alloys were oxidized 20 hours long at 1373K and 1473K. The oxidation rates were determined by observing the weight gain. The macro- and microstructure of formed oxide layer were examined by optical microscopy. The AI-IMg-3Si-5Zn-lCu alloy revealed the best oxidation behavior, but formedoxide layer was inhomogeneous.The oxidation rate were accelerated, and the uniform growth of the oxide layer with fine microstructure were obtained by putting a thin layer of $SiO_2$ on the surface of the alloy.
하용수(Yong-Soo Ha),김윤태(Yun-Tae Kim) 한국해양공학회 2015 韓國海洋工學會誌 Vol.29 No.1
Geosynthetics such as geogrids or geotextiles have been widely used to improve the bearing capacity of soft ground. This study investigated the California bearing ratio (CBR) of waste fishing net (WFN)-reinforced sand. CBR tests were carried out to evaluate the improvement in the bearing capacity of WFN-reinforced sand with different embedded depths. The experimental results indicated that the CBR increased as the embedded depth of the WFN decreased. The bearing capacity ratio (BCR) is the ratio of the bearing capacity of reinforced ground to that of unreinforced ground. The BCR at the penetration depths of 2.5 mm, 5 mm, and the peak point decreased with an increase in the embedded depth.
토목섬유를 이용한 인공어초 침하 저감에 대한 실험 연구
하용수(Yong-Soo Ha),김윤태(Yun-Tae Kim) 한국지반신소재학회 2015 한국지반신소재학회 논문집 Vol.14 No.3
인공어초는 해양환경을 개선하고 어류와 해양생물들에게 주거지를 제공하는 인공 수중 구조물이다. 특히 인공어초가 느슨한 모래, 연약한 점성토와 같은 연약지반에 설치될 경우 인공어초의 자중에 의해 인공어초의 침하가 발생하게 된다. 본 연구에서는 관입실험을 통해 토목섬유 보강 넓이에 따른 인공어초의 지지력 보강효과를 확인하였고, 실내 대형 토조 실험을 통해 침하 저감효과를 확인하였다. 관입실험과 실내 대형 토조 실험을 통해 지오그리드와 같은 토목섬유를 인공어초 하부에 포설하게 되면 지지력이 증가하며, 침하가 감소하는 경향을 나타내었다. An artificial reef is a human-made underwater structure to improve marine environment and to provide a habitat for fish and other ocean wildlife. An artificial reef is placed on the ocean ground. In soft ground like most of the seabed soil, the ground has been settled due to weight of artificial reef. This study investigated the bearing capacity and settlement reduction effect of geosynthetics which were reinforced on the ground in a large size tank. Penetration tests and large soil tank laboratory tests were performed to investigate settlement reduction effect and bearing capacity on artificial reef with different spreading area of geogrid. Laboratory test results indicate that the spreaded geogrid under artificial reef reduce the settlement of ground and increase bearing capacity of ground.
하용수 ( Yong-soo Ha ) 한국중견기업학회 2020 중견기업연구 Vol.7 No.2
오늘날 중소기업은 혁신적 경영환경을 선도하는 데 중추적 역할을 담당하고 있다. 해외의 중소기업들은 신규 기업 설립, 일자리 창출, 디지털 전환, 글로벌 시장 진출 등 다양한 분야에서 경영환경을 선도하고 있는 반면, 국내 중소기업들은 핵심 경쟁력을 확보하고 있음에도 다양한 내, 외부 요인으로 인해 중견기업으로 발돋움하지 못하고 있다. 본 연구는 OECD 국가들의 중소기업 경영환경과 국내 중소기업 경영환경을 비교하여 국내 중소기업 경영환경의 장, 단점을 분석하였다. 이를 통해 세계 각국의 중소기업 정책을 기반으로 국내 중견기업 육성을 위한 정책 솔루션을 제안하였다. 하나의 사례로 디지털패션생태계를 구축한 무신사 사례를 제시하였다. Today, SMEs are playing a pivotal role in leading an innovative business environment. Overseas SMEs are leading the business environment in various fields such as establishing new companies, creating jobs, digital transformation, and entering the global market. However, despite securing core competitiveness, domestic SMEs have not been able to develop into high potential enterprises due to various internal and external barriers. This study compared the business environment of SMEs in OECD countries with the business environment of SMEs in Korea and analyzed the advantages and disadvantages of domestic SMEs environment. Based on the policies of SMEs in OECD countries, policy solutions were proposed to foster high potential enterprises in Korea. As an example, we present a case of Musinsa, which established a digital fashion ecosystem.
하용수(Yong-Soo Ha),김윤태(Yun-Tae Kim) 한국지반신소재학회 2014 한국토목섬유학회 학술발표회 Vol.2014 No.11
Geosynthetics such as geogrid has been widely used to improve the bearing capacity of the soft ground. This study investigates CBR values of waste fishing net(WFN) - reinforced sand for recycling WFN as a geosynthetic material. CBR tests were carried out to evaluate the improvement of bearing capacity of WFN - reinforced sand with different embedded depths. The experimental results indicated that CBR values increased as embedded depths of WFN decreased. Bearing capacity ratio(BCR) is the ratio of bearing capacity of reinforced ground to that of unreinforced ground. BCR values at the penetration depths of 2.5mm, 5mm, peak point decreased with an increase in embedded depth.