• Title/Summary/Keyword: bar code

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How does the gas in a disk galaxy affect the evolution of a stellar bar?

  • Seo, Woo-Young;Kim, Woong-Tae
    • The Bulletin of The Korean Astronomical Society
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    • v.42 no.2
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    • pp.44.1-44.1
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    • 2017
  • In barred galaxies, gaseous structures such a nuclear ring and dust lanes are formed by a non-axisymmetric stellar bar potential, and the evolution of the stellar bar is influenced by mass inflows to the center and central star formation. To study how the presence of the gas affects the evolution of the stellar bar, we use the mesh-free hydrodynamics code GIZMO and run fully self-consistent three-dimensional simulations. To explore the evolution with differing initial conditions, we vary the fraction of the gas and stability of initial disks. In cases when the initial disk is stable with Q=1.2, the bar strength in the model with 5% gas is weaker than that in the gas-free model, while the bar with 10% gas does not form a bar. This suggests that the gaseous component is unfavorable to the bar formation dynamically. On the other hand, in models with relatively unstable disk with Q=1.0, the presence of gas helps form a bar: the bar forms more rapidly and strongly as the gas fraction increases. This is because the unable disks form stars vigorously, which in turn cools down the stellar disk by adding newly-created stars with low velocity dispersion. However, the central mass concentration also quickly increases as the bar grows in these unstable models, resulting in fast bar dissolution in gas rich models. We will discuss our results in comparison with previous work.

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Cracking Behavior of Steel-Concrete Composite Girders at Negative Moment Region (합성거더 부모멘트부의 균열거동 평가)

  • Youn, Seok-Goo;Seol, Dae-Ho;Ryu, Hyung-Keun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05a
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    • pp.402-405
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    • 2006
  • Inner support regions of continuous steel and concrete composite bridge decks, transverse crackings are easely developed by tensile forces due to live loads and primary and secondary effects of concrete shrinkage. Since these cracks have an influence on the durability of bridge decks, crack width should be controlled within allowable limit values. Although crack width is a function of steel stress, bar diameter, bar spacing, etc, the current code for the amount of longitudinal reinforcements provides only one value of 2 percent of the concrete area. In order to investigate cracking bahaviors of composite girders with the variation of the longitudinal steel ratios, negative flexural tests are conducted on five composite girders and crack width and crack spacing are compared to ACI Code and Eurocode. Based on the test results, it is discussed the suitability of the current code for the longitudinal steel ratio.

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A Study on Interfacial Bond Capacity of Deformed Bars to Concrete : Top Bars and Epoxy-Coated Bars (콘크리트와 이형철근의 계면 부착성능 : 상단철근 및 에폭시도막철근 효과)

  • 강석원;홍건호;정일영
    • Proceedings of the Korea Concrete Institute Conference
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    • 1995.10a
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    • pp.204-209
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    • 1995
  • The influence of the interfacial properties on the bond capacity of reinforcing bars to concrete is studied in this paper. In this study, the deterioration of the interfacial bond capacity when top-cast bars or epoxy-coated bars are used is examined. The effect of such variables on bond capacity in reinforced concrete is studied by experiment which use beam-end specimens. The main objective of this study is that comparing the test results and the requirements in ACI 318-89 code. the verification of the factor in ACI code is also presented in this paper. The results of the test show that "top bar effect" is considerably affected by the slump of fresh concrete, so the influence of slump shoud be taken into account for top bar effect factor in code. Test results also shows that the bond-slip curve of the epoxy-caoted bars is similiar to that of the uncoated and bond strength is reduced about 15% and that coating thickness seems to influence the bond strength deterioration.rioration.

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Structural Performance of Mortar-filled Sleeve Splice for SD500 High-strength Reinforcing Bar under Cyclic Loading (반복하중을 받는 SD500 고강도 철근용 모르타르 충전식 슬리브 철근이음의 구조성능)

  • Kim, Hyong-Kee
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.6
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    • pp.180-192
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    • 2008
  • The purpose of this research is to evaluate the structural performance of mortar-filled ductile cast iron sleeve splice developed for SD500 high-strength reinforcing bar under cyclic loading. The test variables adopted in this study are the development length of bar, compressive strength of mortar, bar size, sleeve types and others. In this research, it is showed that the mortar-filled sleeve splice for SD500 high-strength bar satisfied the structural performance required in ACI, AIJ code as well as domestic code. Also the results of experimental research presented in this paper provided basic engineering data for developing a reasonable design method of mortar-filled sleeve splice for SD500 high-strength reinforcing bar.

Applicability of Current Design Code to Class B Splice of SD600 Re-Bars (SD600 철근의 B급 겹침 이음에 대한 현행설계기준의 적용성)

  • Choi, Won-Seok;Chung, Lan;Kim, Jin-Keun;Park, Hong-Gun
    • Journal of the Korea Concrete Institute
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    • v.23 no.4
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    • pp.449-459
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    • 2011
  • An experimental study was performed to evaluate the applicability of current design code to the class B splice of SD600 reinforcing bars. Twelve simply supported beam and slab specimens with re-bar splices were tested under monotonic loading. Parameters for this test were re-bar diameter, concrete cover thickness, concrete strength, and stirrup spacing. Concrete strengths ranged 24.7~55.3 MPa. Most of the specimens were designed to satisfy the class B splice length specified by current design code. Average bar stresses resulting from this test were compared with the predictions by the KCI code provisions. Based on the result, the applicability of the current design code to SD600 re-bars were evaluated. The re-bar splices gave satisfactory performance for all D13 re-bar splices and for D22 and D32 splices with transverse reinforcement. On the basis of the test result, for D22 and the greater diameter bars, the use of either transverse reinforcement of the thicker concrete cover was recommended.

A Study on the Method of High-Speed Reading of Postal 4-state Bar Code for Supporting Automatic Processing (우편용 4-state 바코드 고속판독 방법에 관한 연구)

  • Park, Moon-Sung;Kim, Hye-Kyu;Jung, Hoe-Kyung
    • The KIPS Transactions:PartD
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    • v.8D no.3
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    • pp.285-294
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    • 2001
  • Recently many efforts on the development of automatic processing system for delivery sequency sorting have been performed in ETRI, which requires the use of postal 4-state bar code system to encode delivery points. This paper addresses the issue on the extension of read range and the improvement of image processing method. For the improvement of image processing procedure, applied information acquisition method through basic two thresholds onto the horizontal axial line of gray image based on reference information of 4-state bar code symbology. Symbol values are computed after creating two threshold values based on the obtained information through search of horizontal axial values. The implementation result of 4-state bar code reader are obtained the symbol values within 30~60 msec (58,000~116,000 mail item/hour)without noise removal or image rotation in spite of the incline $\pm 45^{\circ}$.

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Prediction of Laminar Flame Thickness of Ethanol-Air Pre-Mixture (에탄올-공기 예혼합기의 층류 화염두께 예측)

  • Kwon, Soon-Ik;Kim, Sang-Jin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.11
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    • pp.1417-1423
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    • 2004
  • The thickness of laminar flame and preheat zone was computed from equation with burning velocity and the temperature profile, which is obtained by using premix code of Chemkin program for ethanol-air mixture. The computations were carried out under the unburned gas pressure 0.5bar-30bar and temperature of 300k-700K at 1.0. A difference flame thickness showed between temperature profile and equation with burning velocity. The ratio of flame thickness derived from the equation was about 45∼65% of the temperature profile, and the thickness of preheat zone was about 67.1% of the flame thickness. The flame thickness was decreased by increasing the pressure and temperature, but the effect of pressure is more significant than the effect of temperature on the flame thickness. The flame thickness was predicted by using the following equation. X(mm) = $X_{st}$ (T/300)$^{-0}$.65/(P)$^{-0}$.68/ (0.5bar$\leq$P$\leq$30bar, 300K$\leq$T$\leq$700K)K)

Structural Performance of Steel Pipe Splice for SD500 High-strength Reinforcing Bar under Cyclic Loading

  • Kim, Hyong-Kee
    • Architectural research
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    • v.10 no.1
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    • pp.13-23
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    • 2008
  • It is the purpose of this study to evaluate the structural performance of steel pipe splice for SD500 high-strength reinforcing bar, through a cyclic loading test. The experimental variables adopted in this study include the development length of rebar, the type of sleeve, and size of reinforcing bar, among others. The results of this study showed that the developed steel pipe splice system for SD500 high-strength reinforcing bar, retained the structural performance required in domestic, ACI and AIJ code. It is considered that the study result presented in this paper can be helpful in developing a reasonable design method for a steel pipe splice system for SD500 high-strength reinforcing bar.

An Experimental Study on the Evaluation of Shear Performance of PVA Fiber Reinforced RC Deep Beam with High Strength Headed Rebar

  • Kim, Seunghun;Lee, Kyuseon;Lee, Yongtaeg
    • Architectural research
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    • v.19 no.4
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    • pp.109-115
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    • 2017
  • This study is done to evaluate how existence of shear-span ratio and shear reinforcing bar effects on shear performance from through shear experiment using PVA fiber reinforced ferroconcrete building. Ratio of shear-span was set 1, 1.7, and arrangement of shear reinforcing bar was set with KCI2012 regulation. In result, subject with less shear-span ratio, and shear reinforcing bar with arrangement of bar shows high stiffness. Subjects with high shear-span ratio show large difference depending on existence of shear reinforcing bar. Therefore, theoretical shear strength followed by CEB code underestimates experimental shear strength by 43.9%. Shear strength of the deep beam with headed bars is more affected by the bearing strength of head than the bond strength of bar.

A Study of Mobile Content Generation System using 2-Dimensional bar code in Smart Device Environment (스마트 기기 환경에서 2차원 바코드를 활용한 모바일 콘텐츠 생성 시스템 연구)

  • Jin, Byung-Wook;Lee, Keun-Wang
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.4
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    • pp.2349-2354
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    • 2014
  • While the number of smart phone subscribers excessing 30 million people, Korea is leaping into the 'smart powerhouse' from IT powerhouse. The popularizat+ion of smart devices so called 'PC in the hand', brought surely change to people's life style, and also it had led to a revolutionary change to and also to business and government. In several corporations of each countries, a variety of smart devices smart devices such as smart phone, tablet PC and E-books have been developing. Nowadays, the usage of the smart phone is not only the simple function calling. It has become a culture of the terminal type in the hand anywhere at any time, which makes can communicate with the others in anywhere and anytime. However, some of the subscribers who visit the website for PC version with the mobile devices screen, can feel kind of discomfort while surfing the net on a smartphone devices because the install of the existing video and flash files and the screen size for computer is not available for mobile devices. Therefore, in this paper, we studied on effective mobile contents generation program using QR code that is two dimensions bar code under the smart device environment. Also, unlike previous QR code generator that decorate standardized design, we realize an original QR code generation system from user perspective.