• 제목/요약/키워드: macro/micro

검색결과 796건 처리시간 0.021초

Milli-Structure 생산기술개발 (Development of Manufacturing Technology for Milli-Structure)

  • 나경환;박훈재;조남선
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2000년도 춘계학술대회 논문집
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    • pp.1039-1042
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    • 2000
  • This research will deal with Innovative manufacturing technology for milli-structure manufacturing technology which is located betweon the traditional manufacturing technology for macro-sized structure and the recently emerging manufacturing technology for micro-scaled structure such as MEMS. There are four fields in this research, which are micro-sheet metal forming technology, micro-bulk forming technology micro-molding technology and micro die making technology. As a project for new-technology in next generation, this research will be carried out through three terms and each term and be composed of three years.

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Numerical Simulation of the Effect of Finite Diaphragm Rupture Process on Micro Shock Tube Flows

  • ;김희동
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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    • pp.309-317
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    • 2012
  • Recent years have witnessed the use of micro shock tube in various engineering applications like micro combustion, micro propulsion, particle delivery systems etc. The flow characteristics occurring in the micro shock tube shows a considerable deviation from that of well established conventional macro shock tube due to very low Reynolds number and high Knudsen number effects. Also the diaphragm rupture process, which is considered to be instantaneous process in many of the conventional shock tubes, will be crucial for micro shock tubes in determining the near diaphragm flow field and shock formation. In the present study, an axi-symmetric CFD method has been applied to simulate the micro shock tube, with Maxwell's slip velocity and temperature jump boundary conditions. The effects of finite diaphragm rupture process on the flow field and the shock formation was investigated, in detail. The results show that the shock strength attenuates rapidly as it propagates through micro shock tubes.

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한국 연안산 해산 무척추동물의 미네랄 함량과 영양평가 (Mineral Content and Nutritional Evaluation of Marine Invertebrates from the Korean Coast)

  • 목종수;이두석;심길보;윤호동
    • 한국수산과학회지
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    • 제42권2호
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    • pp.93-103
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    • 2009
  • To measure the mineral contents of marine invertebrates, we collected 239 individuals from 52 species from the east (Pohang), west (Gunsan), and south (Tongyeong) coasts of Korea: 34 species of molluscan shellfish (Gastropoda and Bivalvia), 6 species of Cephalopoda, 8 species of Crustacea, and 4 other species. The mean contents of the macro mineral in the 100g edible portion of molluscan shellfish were high in the oder of Na (355.1 mg), P (128.1 mg), K (110.8 mg), Mg (83.8 mg) and Ca (57.5 mg). And the mean contents of the micro mineral in the molluscan shellfish were high in the oder of Fe ($41.12{\mu}g/g$), Zn ($30.48{\mu}g/g$), Mn ($3.81{\mu}g/g$), Cu ($3.49{\mu}g/g$) and Ni ($0.35{\mu}g/g$). We could not observe clear regional variation in the mineral content of the molluscan shellfish species. The mean contents of the macro mineral in the 100g edible portion of other marine invertebrates (Cephalopoda, Crustacea, etc.) were high in the oder of Na (400.7 mg), P (145.1 mg), K (105.0 mg), Mg (63.2 mg) and Ca (49.0 mg). And the mean contents of the micro mineral in other marine invertebrates were high in the oder of Zn ($24.4{\mu}g/g$), Fe ($13.8{\mu}g/g$), Cu ($4.88{\mu}g/g$), Mn ($2.14{\mu}g/g$) and Ni ($0.12{\mu}g/g$). The daily average intakes of the macro mineral through fisheries products consisted of P (125.9 mg), Na (119.3 mg), K (101.8 mg), Ca (31.0 mg), Mg (27.6 mg). And the daily average intakes of the micro mineral through fisheries products consisted of Zn (0.92 mg), Fe (0.68 mg), Cu (0.12 mg) and Mn (0.07 mg). The respective intakes of the minerals (P, Mg, Na, Ca, K) from fish were about 18.0, 7.9, 8.0, 4.4 and 2.2% of the dietary reference intakes for Koreans (KDRIs) set by the Korean Nutrition Society. And the respective intakes of micro mineral (Cu, Zn, Fe, Mn) from fish were about 14.6, 9.2, 6.7, and 2.1% of the dietary reference intakes for Koreans (KDRIs). Therefore, fisheries products play a very important role as a source of mineral.

Assessment of Perspective Development of Transport and Logistics Systems at Macro and Micro Level under the Conditions of Industry 4.0 Integration

  • Maiboroda, Olha;Bezuhla, Liudmyla S.;Gukaliuk, Andrii F.;Shymanska, Viktoriia;Momont, Tetiana;Ilchenko, Tetiana V.
    • International Journal of Computer Science & Network Security
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    • 제21권3호
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    • pp.235-244
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    • 2021
  • The change of the development of transport and logistics systems occurs with the active change of technology and the advent of the era of Industry 4.0. It requires modernization of approaches to the development of transport and logistics systems at the macro and micro levels. The present study aims to identify perspective directions of development and evolution, find out the existing obstacles in the integration of technological solutions of transport and logistics systems at the macro and micro levels. This study is based on a quantitative and qualitative methodology for assessing the level of integration of technologies into transport and logistics systems to study the prospects for their development at the micro level. Macroeconomic indicators of transport and logistics in the context of different regions of the world were used to quantify the development prospects. For a qualitative assessment of the development of the transport and logistics system, the case study method was used. The object of the study was selected logistics company Sensco Logistics Inc., Austin TX. At the macro level, countries with more innovative logistics sectors have stronger mechanisms for coordinating private sector activities. Simplification of administrative procedures of control and regulation by the public sector in order to facilitate trade between countries is a promising direction for the development of transport and logistics systems. Such reforms are more effective in developing a "rigid" transport infrastructure. The integration of Industry 4.0 technology solutions into the international logistics sector is defined by political and legal barriers, especially in developing countries. In low-income countries, hard and soft infrastructure reforms are hindering the development of logistics companies that provide transport services. This determines the national level of development of transport and logistics systems, and in general the global level of development of transport and logistics. In developed countries, the legal barriers to the development of new technological logistics are environmental requirements for the integration of technologies into the transport system. These trends are slowing down the development of International Logistics, which, compared to other industries, is slower to integrate Industry 4.0 technologies. This study combines macroeconomic factors that determine the prospects for the development of transport and logistics systems at the micro level.

Effectiveness of steel fibers in ultra-high-performance fiber-reinforced concrete construction

  • Dadmand, Behrooz;Pourbaba, Masoud;Sadaghian, Hamed;Mirmiran, Amir
    • Advances in concrete construction
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    • 제10권3호
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    • pp.195-209
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    • 2020
  • This study investigates the behavior of ultra-high-performance fiber-reinforced concrete (UHPFRC) with hybrid macro-micro steel and macro steel-polypropylene (PP) fibers. Compression, direct and indirect tension tests were carried out on cubic and cylindrical, dogbone and prismatic specimens, respectively. Three types of macro steel fibers, i.e., round crimped (RC), crimped (C), and hooked (H) were combined with micro steel (MS) and PP fibers in overall ratios of 2% by volume. Additionally, numerical analyses were performed to validate the test results. Parameters studied included, fracture energy, tensile strength, compressive strength, flexural strength, and residual strength. Tests showed that replacing PP fibers with MS significantly improves all parameters particularly flexural strength (17.38 MPa compared to 37.71 MPa). Additionally, the adopted numerical approach successfully captured the flexural load-deflection response of experimental beams. Lastly, the proposed regression model for the flexural load-deflection curve compared very well with experimental results, as evidenced by its coefficient of correlation (R2) of over 0.90.

기능좌표계를 이용한 교시 및 실행 전문가 시스템(TOES/WCS)에 있어서의 로보트의 동작제어 개선에 관한 연구 (A study on improvement of robot motion control in teaching and operating expert system/world coordinate system (TOES/WCS))

  • 이순요;한장희
    • 대한인간공학회지
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    • 제8권1호
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    • pp.41-46
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    • 1989
  • The purpose of this study is to improve robot motion control in teaching and operating the expert system/world coordinate system (TOES/WCS) constructed in the previous study. The major contribution of this study is reduction of the inaccuracy in coordinated reading and the movement time of robots in macro motion control. This study also reduces undesirable time of micro motion control by using an unit control (UC) and a micro unit control (MUC) in micro motion control.

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UNIFICATION OF THERMO-PHYSICS OF MATERIALS AND MECHANICS OF STRUCTURES - TOWARD A LIFE SPAN SIMULATOR OF STRUCTURAL CONCRETE -

  • Maekawa, K.;Ishida, T.
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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    • pp.29-46
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    • 1999
  • The performance based design obligates quantitative assessment of required performances by means of transparent and objective science. In this design scheme, simulation of both macro and micro-scale structural behaviors is thought to be a powerful tool. This paper proposes a way how to unify the structural safety and serviceability check method and durability assessment of RC structures. Though component chemical-physical processes are crudely assumed, system dynamics of micro-scale pore structure formation and macro-scale defects and deformation of structures was shown as possible and promising approach in future. The authors understand that the unification of structural and durability design has just started. For further progress and development, predictive tool of structural behaviors from birth to death of concrete under any specified environment and load serves as an essential technicality.

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마이크로 및 매크로 섬유를 사용한 하이브리드 HPFRCC의 역학적 특성에 관한 연구 (A Study on the Mechanical Properties of Hybrid HPFRCs Using Micro and Macro Fibers)

  • 김재환;이의배;김영선;김영덕;주지현;김무한
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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    • pp.276-279
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    • 2004
  • Concrete is one of the principal materials for the structure and it is widely used all over the world. but it shows extremely brittle failure under bending and tensile load. Recently to improve such a poor property. High Performance Fiber Reinforced Cementitious Composites (HPFRCC) have been developed. and it are defined by an ultimate strength higher than their first cracking strength and the formation of multiple cracking during the inelastic deformation process. This study is to develop the hybrid HPFRCC with high ductility and strain capacity in bending and tensile load. and the three-point bending test on hybrid HPRFCC reinforced with micro and macro fibers is carried out in this paper. As the results of the bending tests. hybrid HPFRCCs reinforced with PVA40+SF and PVA100+PVA660 showed the high ultimate bending stress, multiple cracks and displacement hardening under bending load.

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A composite crack model for concrete based on meshless method

  • Lu, Xin-Zheng;Jiang, Jian-Jing;Ye, Lie-Ping
    • Structural Engineering and Mechanics
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    • 제23권3호
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    • pp.217-232
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    • 2006
  • A crack model for the fracture in concrete based on meshless method is proposed in this paper. The cracks in concrete are classified into micro-cracks or macro-cracks respectively according to their widths, and different numerical approaches are adopted for them. The micro-cracks are represented with smeared crack approach whilst the macro-cracks are represented with discrete cracks that are made up with additional nodes and boundaries. The widely used meshless method, Element-free Galerkin method, is adopted instead of finite element method to model the concrete, so that the discrete crack approach is easier to be implemented with the convenience of arranging node distribution in the meshless method. Rotating-Crack-Model is proved to be preferred over Fixed-Crack-Model for the smeared cracks of this composite crack model due to its better performance on mesh bias. Numerical examples show that this composite crack model can take advantage of the positive characteristics in the smeared and discrete approaches, and overcome some of their disadvantages.

도서관기획에 있어서 목표실현에 관한 일 고찰 (A Study on the Library Planning to Objectives)

  • 윤영
    • 한국문헌정보학회지
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    • 제28권
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    • pp.3-21
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    • 1995
  • The library as nonprofit organization is required to have micro-planning for the organization itself and macro-planning for the relationship of the organization and its environment. Both the micro and macro planning are rational and effective means to library objectives. The library planning must be based on clearly formulated objectives that will encourage all parts of the organization to work toward the same goal and mission. The planning to library objectives should make programming. which should make processing. The mission here should precede goal. which should precede objectives and objectives should precede activities in planning. There is an integral relationship among them. Just as the objectives of the library may be thought of in a hierarchy such as the above. so the library planning must be based on such a hierarchy from strategic or long range planning to administrative planning, from administrative planning to operational planning or short range ones.

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