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검색결과 92건 처리시간 0.027초

Effect of FRP composites on buckling capacity of anchored steel tanks

  • Al-Kashif, M.A.;Ramadan, H.;Rashed, A.;Haroun, M.A.
    • Steel and Composite Structures
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    • 제10권4호
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    • pp.361-371
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    • 2010
  • Enhancement in the seismic buckling capacity of steel tanks caused by the addition of fiber reinforced polymers (FRP) retrofit layers attached to the outer walls of the steel tank is investigated. Three-dimensional non-linear finite element modeling is utilized to perform such analysis considering non linear material properties and non-linear large deformation large strain analysis. FRP composites which possess high stiffness and high failure strength are used to reduce the steel hoop stress and consequently improve the tank capacity. A number of tanks with varying dimensions and shell thicknesses are examined using FRP composites added in symmetric layers attached to the outer surface of the steel shell. The FRP shows its effectiveness in carrying part of the hoop stresses along with the steel before steel yielding. Following steel yielding, the FRP restrains the outward bulging of the tank and continues to resist higher hoop stresses. The percentage improvement in the ultimate base moment capacity of the tank due to the addition of more FRP layers is shown to be as high as 60% for some tanks. The percentage of increase in the tank moment capacity is shown to be dependent on the ratio of the shell thickness to the tank radius (t/R). Finally a new methodology has been explained to calculate the location of Elephant foot buckling and consequently the best location of FRP application.

한국 전통목가구 평상(平床) 연구 I (A Study on Traditional Korean Furniture, PyeongSang I)

  • 김민경;문선옥
    • 한국가구학회지
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    • 제28권2호
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    • pp.126-134
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    • 2017
  • This study explores PyeongSang, a piece of traditional Korean furniture, in order to make people know the details about what the piece is in the first paper. And based on the paper, PyeongSang will be developed as moulded multi-useful beds and sofas adapting the joint and ornament from the structure and pattern of the piece in the next paper. As the result, it appeared as two styles such as bed types mentioned as SalPyeongSang and ttulmaru in Korean. The pieces have been used from the three Kingdoms period in Korean history. The styles appeared as the structure of four parts with the lower fences called as nangan, the seats jointed by thin wood pieces, the wind hole, and the legs of foot types. The parts were beautifully carved with the ornament such as lattice patterns like geokjamun and manjamun, flower patterns like dangchomun, elephant eyes patterns like ansangmun from the Korean tradition. And the legs showed various shapes such as supports transformed from horse foots, tiger legs and bamboo, and board types carved with elephant eyes and geometric patterns. Hence, in the next paper based on this paper, PyeongSang will be developed as moulded multi-useful beds and sofas adapting the joints and ornaments from the structure and patterns of the piece.

Metagenomic Analysis of the Fecal Microbiomes of Wild Asian Elephants Reveals Microflora and Enzymes that Mainly Digest Hemicellulose

  • Zhang, Chengbo;Xu, Bo;Lu, Tao;Huang, Zunxi
    • Journal of Microbiology and Biotechnology
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    • 제29권8호
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    • pp.1255-1265
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    • 2019
  • To investigate the diversity of gastrointestinal microflora and lignocellulose-degrading enzymes in wild Asian elephants, three of these animals living in the same group were selected for study from the Wild Elephant Valley in the Xishuangbanna Nature Reserve of Yunnan Province, China. Fresh fecal samples from the three wild Asian elephants were analyzed by metagenomic sequencing to study the diversity of their gastrointestinal microbes and cellulolytic enzymes. There were a high abundance of Firmicutes and a higher abundance of hemicellulose-degrading hydrolases than cellulose-degrading hydrolases in the wild Asian elephants. Furthermore, there were a high abundance and a rich diversity of carbohydrate active enzymes (CAZymes) obtained from the gene set annotation of the three samples, with the majority of them showing low identity with the CAZy database entry. About half of the CAZymes had no species source at the phylum or genus level. These indicated that the wild Asian elephants might possess greater ability to digest hemicellulose than cellulose to provide energy, and moreover, the gastrointestinal tracts of these pachyderms might be a potential source of novel efficient lignocellulose-degrading enzymes. Therefore, the exploitation and utilization of these enzyme resources could help us to alleviate the current energy crisis and ensure food security.

원위부에 스텐트가 포함된 인조혈관 (Frozen Elephant Trunk)을 이용한 대동맥궁 동맥류 수술 (Aortic Arch Aneurysm Repair using a Prosthetic Graft with a Pre-mounted Distal Stent (Frozen Elephant Trunk))

  • 장형우;정의석;최진호;임청;박계현
    • Journal of Chest Surgery
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    • 제42권3호
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    • pp.375-379
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    • 2009
  • 원위부 대동맥궁에 발생한 대동맥류에 대한 수술을 위해서는 정중흉골 절개술 또는 측방개흉을 통한 수술방법이 있으나 문합 부위의 시야 확보가 용이하지 않은 경우가 자주 있다. 수술 대신 중재시술로 스텐트 그라프트를 삽입하는 방법 또한 가능하지만 동맥류보다 근위부에 충분한 고정 거리를 확보하기 위해서 대동맥궁 분지 일부를 결찰하고 우회로를 조성해야 할 필요가 있다는 제한이 있다. 저자들은 이들 방법의 장점을 취하고자 정중흉골절개술 후 완전 순환 정지 상태에서 대동맥궁을 치환하는 수술 중 외과적 문합 대신 스텐트 그라프트를 이용하여 인조혈관 원위부를 고정하는 방법을 취하여 양호한 결과를 얻은 경험을 보고한다.

스프링 백본과 와이어를 이용한 3자유도 내시경 (3DOF Endoscope with Spring Backbone and Wires)

  • 최동걸;이병주
    • 로봇학회논문지
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    • 제3권3호
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    • pp.203-211
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    • 2008
  • This work proposes structure of spring backbone micro endoscope. For effective surgery in narrow and limited space, many manipulators are developing that different to existed structure. This device can move like elephant nose or snake unlike the existing robots. For this motion, a mechanism that uses spring backbone and wires has been developed. The new type endoscope that has Z axis motion for spring structure, therefore it has 3 degree of freedom, two rotations and one linear motion. And new kinematics for backbone structure is proposed using simple geographic analysis. The Jacobian and stiffness modeling are also derived. Exact actuator sizing is determined using stiffness model. Finally, the proposed kinematics are verified by simulation and experiments.

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Girl-Favored Tessellations Using Technology

  • Sangsook Choi-Kho
    • 한국수학교육학회지시리즈D:수학교육연구
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    • 제9권3호
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    • pp.275-284
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    • 2005
  • Tessellations are the pattern of iterations of geometric symmetry and translation. We can find them in the works of Escher who is the famous Dutch artist, and the American Indean life. Also, we can find the beauty of tessellations in the Korean traditional house door, Buddist temple architecture, palace's fence, etc. In the article, the figures of patterns we present are bird, fish, cat, pig, elephant, penguin, child and horse riding man, including Escher's, which are constructed using the computer geometric program, GSP (Geometer's Sketchpad). We want to talk about girl's disposition toward mathematics related to the figures. If they are supported by this kind of interesting figures constructed by their own hands, students will have more interest in learning geometric figures.

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The Ripple Effects of Climate X-Events

  • Sang-Keun Cho;Ji-Min Lee;Sang-Hyuk Park
    • International Journal of Advanced Culture Technology
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    • 제11권3호
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    • pp.83-88
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    • 2023
  • The increasing global average temperature and the emergence of various abnormal climate phenomena are already being experienced in reality. The problems arising from climate change are expanding and becoming catastrophic, despite the efforts of various organizations to prevent them. In order to avoid climate issues from becoming black elephants, we conducted interviews with emergency planning officer from various institutions to identify potential X-events caused by climate change. The results of analyzing the anticipated X-events by these emergency planning officer revealed a chain of ripple effects associated with their occurrence. This implies that once an X-event happens, its influence is broader and more significant. Through this study, we aim to share the understanding of the ripple effects of climate X-events with many people, raising awareness of the severity of climate issues. We hope that this will serve as a starting point for more institutions, individuals, and nations to make efforts in resolving climate problems, turning X-events into opportunities rather than crises.

6축 협동 로봇 암을 이용한 바리스타 로봇 개발 (Development of Baristar Robot Using 6-DOF Cooperative Robot Arm)

  • 김용환;박찬흠;오경택;오유민
    • 한국정보처리학회:학술대회논문집
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    • 한국정보처리학회 2022년도 추계학술발표대회
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    • pp.785-787
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    • 2022
  • 인공지능 로봇 산업의 발달로 우리의 일상생활 속 다양한 곳에서 활용되고 있다. 그러나 로봇의 고비용, 높은 진입 장벽의 문제로 상용화하기에 쉽지 않은 것은 사실이다. 따라서 본 논문에서는 기존 바리스타 로봇의 고비용, 높은 진입 장벽의 한계점을 해결하기 위해 저렴한 오픈소스 로봇인 elephant robotics사의 my cobot 280 pi와 Python을 통한 영상처리 기술을 접목하여 가성비 바리스타 로봇을 제작하고자 한다.

Design optimization of turning machine process

  • T. Jagan;S. Elizabeth Amudhini Stephen
    • Coupled systems mechanics
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    • 제13권3호
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    • pp.219-229
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    • 2024
  • By introducing optimization algorithms into the machining process, product quality can be improved, time saved, and costs reduced. The cutting speed and feed can be handled by the turning machine. The approach of optimizing is used to manage pyrotechnics, Lawler's, greedy, bacterial colony, elephant herding, ant lion, spiral, auction, and pattern search for these ten odd ways. Ten artificial optimization methodologies were used to investigate the time and cost of a turning machine. It has been discovered how to create the optimal turning machine procedure. The best solution approach for the turning machine process problem is found, and the results are verified using ANSYS.