• Title/Summary/Keyword: Plastic Forming

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Experimental Study on Two-Seam Cold Formed Square CFT Column to Beam Connections with Asymmetric Diaphragms (상하 이형 다이아프램으로 보강된 2심 냉간성형 각형 CFT 기둥-보 접합부의 실험적 연구)

  • Oh, Heon Keun;Kim, Sun Hee;Choi, Sung Mo
    • Journal of Korean Society of Steel Construction
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    • v.25 no.1
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    • pp.35-45
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    • 2013
  • The concrete-filled tube column has the excellent structural performance. But it is difficult to connect with column and beam because of closed section. It suggests that pipe should be produced by welding two sides together where two shapes are joined after a channel is pre-welded onto the three sides in order to form an internal diaphragm. The upper diaphragm of the connection used the horizontal plate and the lower diaphragm used the Vertical plate. This research performed 6 monotonic tension experiments describing the connection upside and downside in order to evaluate the structural capability of the offered connection. And the cyclic loading experiment was performed about 2 T-Type column to beam connections. As to the experimental result edge cutting geometry, there was no big effect. An increase in the number of holes of the plate ultimate strength was increased by 5% and The thickness of the plate increases, the maximum strength was increased by 4%. T-Type connections until it reaches the plastic moment showed a stable behavior.

A Study on the Seismic Response of a Non-earthquake Resistant RC Frame Using Inelastic Dynamic Analyses (비선형 동적 해석을 이용한 비내진 상세 RC 골조의 지진거동 특성 분석)

  • Jeong, Seong-Hoon;Lee, Kwang-Ho;Lee, Soo-Kueon
    • Journal of the Korea Concrete Institute
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    • v.22 no.3
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    • pp.381-388
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    • 2010
  • In this study, characteristics of the seismic response of the non-earthquake resistant reinforced concrete (RC) frame were identified. The test building is designed to withstand only gravity loads and not in compliance with modern seismic codes. Smooth bars were utilized for the reinforcement. Members are provided with minimal amount of stirrups to withstand low levels of shear forces and the core concrete is virtually not confined. Columns are slender and more flexible than beams, and beam-column connections were built without stirrups. Through the modeling of an example RC frame, the feasibility of the fiber elementbased 3D nonlinear analysis method was investigated. Since the torsion is governed by the fundamental mode shape of the structure under dynamic loading, pushover analysis cannot predict torsional response accurately. Hence, dynamic response history analysis is a more appropriate analysis method to estimate the response of an asymmetric building. The latter method was shown to be accurate in representing global responses by the comparison of the analytical and experimental results. Analytical models without rigid links provided a good estimation of reduced stiffness and strength of the test structure due to bond-slip, by forming plastic hinges closer to the column ends. However, the absence of a proper model to represent the bond-slip poased the limitations on the current inelastic analysis schemes for the seismic analysis of buildings especially for those with round steel reinforcements. Thus, development of the appropriate bond-slip model is in need to achieve more accurate analysis.

Acquisition and Verification of Dynamic Compression Properties for SHPB of Woven Type CFRP (Woven Type CFRP의 SHPB에 대한 동적 압축 물성 획득 및 검증)

  • Park, Ki-hwan;Kim, Yeon-bok;Kim, Jeong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.48 no.5
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    • pp.363-372
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    • 2020
  • Dynamic compressive material properties at high strain rates is essential for improving the reliability of finite element analysis in dynamic environments, such as high-speed collisions and high-speed forming. In general, the dynamic compressive material properties for high strain rates can be obtained through SHPB equipment. In this study, SHPB equipment was used to acquire the dynamic compressive material properties to cope with the collision analysis of Woven tpye CFRP material, which is being recently applied to unmanned aerial vehicles. It is also used as a pulse shaper to secure a constant strain rate for materials with elastic-brittle properties and to improve the reliability of experimental data. In the case of CFRP material, since the anisotropic material has different mechanical properties for each direction, experiments were carried out by fabricating thickness and in-plane specimens. As a result of the SHPB test, in-plane specimens had difficulty in securing data reproducibility and reliability due to fracture of the specimens before reaching a constant strain rate region, whereas in the thickness specimens, the stress consistency of the specimens was excellent. The data reliability is high and a constant strain rate range can be obtained. Through finite element analysis using LS-dyna, it was confirmed that the data measured from the pressure rod were excessively predicted by the deformation of the specimen and the pressure rod.

Laser crystallization in active-matrix display backplane manufacturing

  • Turk, Brandon A.;Herbst, Ludolf;Simon, Frank;Fechner, Burkhard;Paetzel, Rainer
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.1261-1262
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    • 2008
  • Laser-based crystallization techniques are ideally-suited for forming high-quality crystalline Si films on active-matrix display backplanes, because the highly-localized energy deposition allows for transformation of the as-deposited a-Si without damaging high-temperature-intolerant glass and plastic substrates. However, certain significant and non-trivial attributes must be satisfied for a particular method and implementation to be considered manufacturing-worthy. The crystallization process step must yield a Si microstructure that permits fabrication of thin-film transistors with sufficient uniformity and performance for the intended application and, the realization and implementation of the method must meet specific requirements of viability, robustness and economy in order to be accepted in mass production environments. In recent years, Low Temperature Polycrystalline Silicon (LTPS) has demonstrated its advantages through successful implementation in the application spaces that include highly-integrated active-matrix liquid-crystal displays (AMLCDs), cost competitive AMLCDs, and most recently, active-matrix organic light-emitting diode displays (AMOLEDs). In the mobile display market segment, LTPS continues to gain market share, as consumers demand mobile devices with higher display performance, longer battery life and reduced form factor. LTPS-based mobile displays have clearly demonstrated significant advantages in this regard. While the benefits of LTPS for mobile phones are well recognized, other mobile electronic applications such as portable multimedia players, tablet computers, ultra-mobile personal computers and notebook computers also stand to benefit from the performance and potential cost advantages offered by LTPS. Recently, significant efforts have been made to enable robust and cost-effective LTPS backplane manufacturing for AMOLED displays. The majority of the technical focus has been placed on ensuring the formation of extremely uniform poly-Si films. Although current commercially available AMOLED displays are aimed primarily at mobile applications, it is expected that continued development of the technology will soon lead to larger display sizes. Since LTPS backplanes are essentially required for AMOLED displays, LTPS manufacturing technology must be ready to scale the high degree of uniformity beyond the small and medium displays sizes. It is imperative for the manufacturers of LTPS crystallization equipment to ensure that the widespread adoption of the technology is not hindered by limitations of performance, uniformity or display size. In our presentation, we plan to present the state of the art in light sources and beam delivery systems used in high-volume manufacturing laser crystallization equipment. We will show that excimer-laser-based crystallization technologies are currently meeting the stringent requirements of AMOLED display fabrication, and are well positioned to meet the future demands for manufacturing these displays as well.

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A Study on Modern Changes in European Clothing - with an emphasis on the effect of industrial revolution - (서구복식(西歐服飾)의 근대적(近代的) 변천(變遷)에 대한 연구(硏究) - 산업혁명(産業革命)의 영향(影響)을 중심(中心)으로 -)

  • Choo, Hi-Kyung;Im, Weon-Ja
    • Journal of the Korean Society of Costume
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    • v.6
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    • pp.7-26
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    • 1982
  • Investigation for industrial revolution has been recognized as an important issue of historical science, since industrial revolution itself was a historical moment in modern economic society and in the forming of modern capitalistic culture. If clothing culture had been developed in close relation to social culture. industrial revolution which gave a base for modern capitalistic culture, would be a birth of modern clothing as well as a moment for modernization of western clothing. As it takes for granted that industrial revolution, historical phenomenon is a developmental base of modern clothing culture. This study tried to enlighten the origin of modern clothing culture phenomenon with investigation of industrial revolution as a historical moment in modern clothing culture through documental study. Historian's point of view and method of studying are important when we investigate the clothing phenomenon. Although culture phenomenon of industrial revolution has been evaluated usually through socialogical aspect, studying for clothing culture phenomenon must be carried out on aethetical as well as well as sociological aspect, on account of dualism of clothing, as it is social and artistic nature. In 19th century, there were technical improvement, changing patterns of production, changing social relation and beginning of mass culture. At the same time clothing culture phenomenon was changed in relation to modern capitalistic society. The findings of the study could be summarized as follows. 1. Technical improvement in textile industry and fitting process brought about mechanization of clothing industry. 2. Appearance of popular clothing culture made it easy to spread to various classes of society. 3. Development of transportation system and communication channel made it internationalization of western clothing. 4. Recognition of importance in functional style of clothing. 5. The pursuit of modern aesthetics made rapid changing mode of clothing. Above distinctive features of modern clothing culture were derived from by-product of machinary culture, mass culture, internationalism, rapidly changing mode of various culture during industrial revolution. Industrial revolution was a change of the material world as well as in industry owing to machine advent, then the culture part that displayed directly these changes was the plastic arts of living that mould the material. The problem of clothing construction caused by industrial revolution was solved by pursuing the functional aesthetics. Clothing phenomenon as a process of value transfer participates mass culture in closs relation to general change of various culture caused by industrial revolution. Therefore western clothing gained the qualities of modern culture, condensed as function, and popularity in the process of modernization.

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Adenocarcinoma of Meibomian Glands and Moll Glands in the Eyelid of Canine (개의 안검에 존재하는 내검판선 및 외검판선에서 발생한 선암종)

  • Yuan, Dong-wei;Goo, Moon-Jung;Yang, Hai-jie;Hong, Il-Hwa;Ki, Mi-Ran;Park, Jin-Kyu;Lee, Hye-Rim;Yoo, Sung-Eun;Jeong, Kyu-Shik
    • Journal of Life Science
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    • v.18 no.3
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    • pp.414-417
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    • 2008
  • A 4-year-old female beagle with progressive exophthalmos and which had a neoplastic mass with diameter of 1.4 cm in the left lower ocular adnexa. Histologically, the mass was composed of hyper-plastic lobules and tubular structures separated by fibrous septum. The well differentiated sebaceous gland forming various sized lobules, and infiltration of mast cells and mononuclear inflammatory cells were observed. Apical decapitation secretion of these tubular structures with basophilic materials in their lumen showed mild sebaceous gland metaplasia. Immunohistochemical studying, cell groups were positive in ${\alpha}-SMA$ and vimentin. The primary tumor was diagnosed as adenocarcinoma originated from moll gland and meibomian gland of the eyelid, and the infiltrating intraocular neoplasm was diagnosed as a malignant mixed tumor.

Changes of Indicator Microorganisms and Pathogenic Bacteria in Spinach during Cook-Chill Process (시금치의 cook-chill 가공 중 오염지표균 및 병원성세균의 변화)

  • Kim, Hye-Jung;Park, Jae-Kap;Lee, Dong-Sun;Paik, Hyun-Dong
    • Korean Journal of Food Science and Technology
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    • v.34 no.5
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    • pp.927-930
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    • 2002
  • Spinach minimally processed using cook-chill and sous vide techniques was vacuum-packed in low gas permeable plastic film, pasteurized at $70^{\circ}C$ for 2 min, cooled rapidly at $3^{\circ}C$, and stored at 3 and $10^{\circ}C$. Contents of mesophilic bacteria, psychrophilic bacteria, anaerobic bacteria, spore-forming bacteria, total coliforms, yeast and molds, fecal Streptococcus, and Enterobacteriacea were measared to identify the degree of food contamination. Number of mesophilic bacteria, detected at $2.2{\times}10^8\;cfu/g$ in raw spinish, decreased to about $6.0{\times}10^3\;cfu/g$ after cook-chill process. During the storage at 3 or $10^{\circ}C$, levels of mesophilic, psychrophilic and anaerobic bacteria increased, whereas total coliforms, yeast and molds, fecal Streptococcus, and Enterobacteriacea were not detected. Twelve strains of Aeromonas hydphila, Escherichia coli O157:H7, Plesiomonas shigelloides, Pseudomonas aeruginosa, Salmonella spp., Shigella spp., Yersinia enterocolitica, Bacillus cereus, Campylococcus spp., Clostridium perfringens, Listeria monocytogenes, and Staphylococcus aureus were examined for detecting the presence of pathogenic bacteria in spinach. B. cereus and C. perfringens were isolated from raw, washed, and cook-chilled spinach, whereas A. hydrophila was isolated only from washed spinach. S. aureus was isolated from raw and washed spinach, but not from cook-chilled spinach. Other pathogenic organisms were not detected in raw, washed, and cook-chilled spinach.

A Mechanical Information Model of Line Heating Process using Artificial Neural Network (인공신경망을 이용한 선상가열 공정의 역학정보모델)

  • Park, Sung-Gun;Kim, Won-Don;Shin, Jong-Gye
    • Journal of the Society of Naval Architects of Korea
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    • v.34 no.1
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    • pp.122-129
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    • 1997
  • Thermo-elastic-plastic analyses used in solving plate forming process are often computationally expensive. To obtain an optimal process of line heating typically requires numerous iterations between the simulation and a finite element analysis. This process often becomes prohibitive due to the amount of computer time required for numerical simulation of line heating process. Therefore, a new techniques that could significantly reduce the computer time required to solve a complex analysis problem would be beneficial. In this paper, we considered factors that influence the bending effect by line heating and developed inference engine by using the concept of artificial neural network. To verify the validity of the neural network, we used results obtained from numerical analysis. We trained the neural network with the data made from numerical analysis and experiments varying the structure of neural network, in other words varying the number of hidden layers and the number of neurons in each hidden layers. From that we concluded that if the number of neurons in each hidden layers is large enough neural network having two hidden layers can be trained easily and errors between exact value and results obtained from trained network are not so large. Consequently, if there are enough number of training pairs, artificial neural network can infer similar results. Based on the numerical results, we applied the artificial neural network technique to deal with mechanical behavior of line heating at simulation stage effectively.

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The Critical Pigment Volume Concentration Concept for Paper Coatings: II. Later-Bound Clay; Ground Calcium Carbonate, and Clay- carbonate Pigment Coatings

  • Lee, Do-Ik
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.34 no.5
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    • pp.18-38
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    • 2002
  • A previous study on the model coatings based on latex-bound plastic pigment coatings (1) has been extended to latex-bound No. 1 clay, ultra-fine ground calcium carbonate (UFGCC), and clay-carbonate pigment mixture coatings, which are being widely used in the paper industry. The latex binder used was a good film-forming, monodisperse S/B latex or 0.15$\mu\textrm{m}$. No. 1 clay was representative of plate-like pigment particles, whereas UFGCC was of somewhat rounded rhombohedral pigment particlel. Both of them had negatively skewed triangular particle size distributions having the mean particle suet of 0.7${\mu}{\textrm}{m}$ and 0.6$\mu\textrm{m}$, respectively. Their packing volumes were found to be 62.5% and 657%, respectively. while their critical pigment volume concentrations (CPVC's) were determined to be 52.7% and 50.5% ( average of 45% caused by the incompatibility and 55.9% extrapolated) by coating porosity, respectively. Each pigment/latex coating system has shown its unique relationship between coating properties and pigment concentrations, especially above its CPVC. Notably, the clay/latex coating system hat shown higher coating porosity than the UFGCC/latex system at high pigment concentrations above their respective CPVC's. It was also found that their coating porosity and gloss were inter-related to each other above the CPVC's, as predicted by the theory. More interestingly, the blends of these two pigments have shown unique rheological and coating properties which may explain why such pigment blends are widely used in the industry. These findings have suggested that the unique structure of clay coatings and the unique high-shear rheology of ground calcium carbonate coatings can be judiciously combined to achieve superior coatings. Importantly, the low-shear viscosity of the blends was indicative of their unique packing and coating structure, whereas their high-shear rheology was represented by a common mixing rule, i.e., a viscosity-averaging. Transmission and scanning electron and atomic force microscopes were used to probe the state of pigment / latex dispersions, coating surfaces, freeze fractured coating cross-sections, and coating surface topography. These microscopic studies complemented the above observations. In addition, the ratio, R, of CPVC/(Pigment Packing Volume) has been proposed as a measure of the binder efficiency for a given pigment or pigment mixtures or as a measure of binder-pigment interactions. Also, a mathematical model has been proposed to estimate the packing volumes of clay and ground calcium carbonate pigments with their respective particle size distributions. As well known in the particle packing, the narrower the particle size distributions, the lower the packing volumes and the greater the coating porosity, regardless of particle shapes.

Study on the Surface Characterization of Structure made of Polyamide 12 manufactured by Additive Manufacturing Process (적층 기법으로 제작한 polyamide 12 소재 적용 구조물 표면 특성 분석 연구)

  • Kim, Moosun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.9
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    • pp.481-487
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    • 2019
  • Additive manufacturing is a state-of-the-art manufacturing process technology in which three-dimensional structures are fabricated by laminating two-dimensional sections of a structure using various materials such as plastic, ceramics, and metals. The additive manufacturing technology has the advantage of high design freedom, while the surface property (roughness) of the finished product varies depending on the process conditions, which necessitates performing a post-process after the products are manufactured. In this study, the surface roughness of a structure made of polyamide 12, which was manufactured by SLS (Selective Laser Sintering) and MJF (Multi Jet Fusion) process was compared. The processing condition was classified by the building orientation of structure as 0, 45, and 90 degrees, which is the angle between the analytical surface and the horizontal plane of the fabrication platform. Structures with a hole of various diameters ranging from 1mm to 10mm were manufactured and the hole characteristics (ratio of hole depth to diameter) and results of the specimens were compared. As a result of the surface characteristics analysis, the surface roughness value of the specimens manufactured with a building orientation of $45^{\circ}$ was the highest in both technologies. In the case of the through-hole structure fabrication, the shape was maintained with 5mm and 10mm diameter holes regardless of the building orientation, although the hole forming was difficult for the smaller holes.