• Title, Summary, Keyword: 인발속도

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Load Sharing Control of Driven Roll in Continuous Caster (연속주조기에서 스트랜드 구동롤의 인발력 분배 제어)

  • 천창근;김철우
    • The Transactions of the Korean Institute of Power Electronics
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    • v.8 no.4
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    • pp.321-327
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    • 2003
  • As the continuous casting process is to product slab with high temperature liquid steel, the main role of strand driven roll is to withdraw slab from mold as operator set up casting speed pattern. The strand driven roll in old cast machine is controlled casting speed only. Due to inaccuracies in drive setting up, varying roll diameters, bulging in the product, withdrawal force was distributed irregularly. As a result, because of horizontal crack in slab comer, high casting speed can't be achieved. In this paper, the correlation between the distribution of withdrawal force and slab quality is investigated and the new control algorithm which can be distributed regularly the withdrawal force of strand driven roll is proposed. The principle of proposed algorithm is not to control motor torque directly but to control motor speed reference according to sharing ratio of withdrawal force which is set up in high level controller. The proposed algorithm implemented in POSCO Kwangyang 1-4 continuous casting plant.

Limit Analysis of Plane Strain Drawing (평면 변형 인발의 극한 해석)

  • 김병민;최인근;최재찬;이종수
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.5
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    • pp.1407-1416
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    • 1991
  • 본 연구에서는 Liu의 수식화를 바탕으로 가공 경화성을 고려하여 수식화를 재 구성하고, 유한요소 프로그램을 개발하여 평면 변형 인발문제를 극한 해석함으로써, 성형에 필요한 한계 하중 및 최적 속도장을 직접적으로 구하였다.수렴되어진 최적 속도장으로 각 요송에서의 변형률 속도, 변형률 및 격자 변형등을 수치적으로 계산함 으로써 가공에 따른 변형 특성도 파악하였다. 한계 하중은 항공기 구조용 소재인 알 루미늄 6061 재료를 이용하여 판재 인발 실험을 행함으로써 얻은 결과치와 비교 검토 하였으며, 유동 특성을 관찰하기 위하여 격자 왜곡(grid distortion) 실험을 하여 얻 은 변형 패턴과 수치 계산에서 구한 격자변형 패턴을 상호 비교하였다.

Analysis of Ultimate Capacity of Plate Anchor on Loading Rate Capacity in Clay (점토 지반에서 인발속도에 따른 판앵커의 극한 인발저항력 분석)

  • Seo, Young-Kyo;Ryu, Dong-Man
    • Journal of Ocean Engineering and Technology
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    • v.27 no.3
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    • pp.15-21
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    • 2013
  • Anchors are primarily designed and constructed to resist outwardly directed loads imposed on the foundation of a structure. These outwardly directed loads are transmitted to the soil at a greater depth by the anchors. Buried anchors have been used for thousands of years to stabilize structures. Various types of earth anchors are now used for the uplift resistance of transmission towers, utility poles, submerged pipelines, and tunnels. Anchors are also used for the tieback resistance of earth-retaining structures, waterfront structures, at bends in pressure pipelines, and when it is necessary to control thermal stress. In this research, we analyzed the uplift behavior of plate anchors in clay using a laboratory experiment to estimate the uplift behavior of plate anchors under various conditions. To achieve the research purpose, the uplift resistance and displacement characteristics of plate anchors caused by the embedment ratio, plate diameter, and loading rate were studied, compared, and analyzed for various cases.

Effect of Embedment Ratio and Loading Rate on Uplift Adhesion Factor of Concrete Driven Pile (근입비와 인발속도가 콘크리트 항타말뚝의 인발부착계수에 미치는 영향)

  • Kim Jong-In;Park Jeong-Jun;Shin Eun-Chul
    • Journal of the Korean Society for Railway
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    • v.8 no.4
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    • pp.367-371
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    • 2005
  • Pile foundations are utilized when soil is so weak that shallow foundations are not suitable or point load is concentrated in small area. Such soil can be formed by the land reclamation works which have extensively been executed along the coastal line of southern and western parts of the Korean Peninsula. The working load at pile is sometimes subjected to not only compression load but also lateral load sad uplift forces. But in most of the practice design, uplift capacity of pile foundation is not considered and estimation of uplift capacity is presumed on the compression skin friction. This study was carried out to determine that the effect of embedment ratio and loading rate on uplift adhesion factor of concrete pile driven in clay. Based on the test results, the critical embedment ratio is about 9. Adhesion factor is constant under the critical embedment ratio, and decreasing over the critical embedment ratio. Also, adhesion factor is increased with the loading rate is increased.

Load Sharing Control by Following Average Torque Current in Continuous Casting (연속 주조 공정에서 평균 토크전류 추종에 의한 인발력 분배 제어)

  • Chun, Chang-Keun;Kim, Cheul-U
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.18 no.3
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    • pp.74-80
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    • 2004
  • If the withdrawal force of strand driven roll which is controlled with predetermined speed isn't distributed regularly in continuous casting process, mold level is changed cyclically and slab quality is not good. In this paper, both casting speed control and load sharing control algorithm of strand driven roll according to ratio which is set up by operator at same time is proposed. The proposed algorithm is to share the withdrawal force by following torque current of each driven roll as average torque current by changing speed reference of each driven roll motor. The load sharing control with anti-wind up for improvement transient state is adopted and the proposed algorithm is implemented in POSCO pilot caster.

Evaluation of Weathered Granite Soil l Geogrid Friction Properties and Pull out Test (화강 풍화토/지오그리드 인발시험 및 마찰특성 평가)

  • 조삼덕;김진만
    • Geotechnical Engineering
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    • v.12 no.4
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    • pp.87-100
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    • 1996
  • The pull -out test has been used to investigate the friction properties between soil and grid type geosynthetics which is useful to measure the passive bearing resistance as well as the skin friction. In this paper, the friction properties between geogrid and a weathered granite soil are investigated by performing various pull-out tests. From the test results, a rational pull out test equipment and test method is suggested by evaluating the effects of major factors (such as geogrid width, location of soil box facing, vertical loads and pulll -out displacement rate, etc.) on pull -out test results.

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Friction Features of Geosynthetics Through the Pullout Test (인발실험을 통한 토목섬유의 마찰특성 평가)

  • Shin, Eun-Chul;Yun, Sock-Ho
    • Journal of the Korean Geosynthetics Society
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    • v.2 no.1
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    • pp.3-13
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    • 2003
  • Recently, construction of the reinforced earth structures, which adopts reinforcing materials of geosynthetic, is rapidly increasing due to its good economic advantages, beautiful appearance, and convenient construction. Nonetheless, the most important factor of interpretation and design of the reinforced earth structures, which is assessment ways of friction features between earth and geosynthetic, has not been standardized yet. It has great difference of interpretation and design methods which suggested to the design engineer. This study is to present the way how to assess more reasonably friction features between geogrid and weathered granite soil through the pullout test. Based on a large-scale pullout test of geogrid, the maximum shear stress, interface fricton angle, and friction efficiency are presented with consideration of various test condition.

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Pull-out Resistance Behavior of the Anchor with the Bump Type Resistors (돌기형 저항체를 설치한 앵커의 인발저항거동)

  • You, Min-Ku;Lee, Sang-Duk
    • Journal of the Korean Geotechnical Society
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    • v.33 no.11
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    • pp.35-43
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    • 2017
  • In this study, the pull-out resistance behavior of the anchor with the bump type resistors at the anchor body was experimentally investigated. In the model tests, the pull-out resistance was measured by pulling out the anchor at a constant speed. Anchor body was installed in the center of the circular sand tank. Pull-out tests were conducted for 10 conditions. The anchor type (existence of the resistor), the friction conditions of the anchor body surface ($1/3{\phi}$, $2/3{\phi}$, ${\phi}$), the bump type resistor set number (1set, 2set, 4set), and the height of resistors (0.05d, 0.10d, 0.20d) were varied. The load-displacement relationship for each conditions was measured during the pull-out tests at a constant speed (1 mm/min). Maximum pull-out length was 80 mm. As a result, the pull-out behavior of the friction type anchor and the expansion type anchor was different. As the number of resistor increased, the maximum pull-out resistance increased and the residual pull-out resistance ratio increased significantly, which were at 171~591 percent larger than that of the friction type anchor.

Direct Tensile Properties of Fiber-Reinforced Cement Based Composites according to the Length and Volume Fraction of Amorphous Metallic Fiber (비정질 강섬유의 길이 및 혼입률에 따른 섬유보강 시멘트복합체의 직접인장특성)

  • Kim, Hong-Seop;Kim, Gyu-Yong;Lee, Sang-Kyu;Choe, Gyeong-Cheol;Nam, Jeong-Soo
    • Journal of the Korea Institute of Building Construction
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    • v.19 no.3
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    • pp.201-207
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    • 2019
  • In this study, the direct tensile properties of amorphous metallic fiber-reinforced cement based composites according to the strain was evaluated. A thin plate-shape amorphous metallic fiber with 15mm and 30mm in length was used. And fiber-reinforced cement based composites were prepared with contents of 1.0, 1.5, 2.0%. The direct tensile test was conducted under the conditions of $10^{-6}/s(static)$ and $10^1/s(dynamic)$ strain rate. As a results, amorphous metallic fiber with a length of 15mm was observed in pull-out behavior from the cement matrix because of the short fiber length and large portion of mixed fiber. On the other hand, amorphous metallic fiber with a length of 30mm were not pulled out from matrix because the bonding force between the fiber and matrix was large due to rough surface and large specific surface area. However, fracture occurred because thin plate shape fibers were vulnerable to shear force. Tensile strength, strain capacity and toughness were improved due to the increase in the fiber length. The dynamic increase factor of L15 was larger that of L30 because the bonding performance of the fiber-matrix interface is significantly affected by the strain rate.

A Study on Pull-out Capacity and Shear resistance strength change by grasses (초본류에 의한 인발저항력 및 전단저항력 변화에 관한 연구)

  • Kim, Taegyun;Chae, Soo Kwon;Chun, Seung Hoon
    • Journal of Wetlands Research
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    • v.15 no.4
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    • pp.431-440
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    • 2013
  • It was tested in field that a Pull-out Capacity and Shear resistance strength change of reed, common reed and sedge which were planted by mat-type turf and used for revegetation of bank. The testes were done for 9 weeks from end of May and the grasses were planted on sandy soil. Roots grew fastly after planted and increasement of a common reed and sedge root were reduced after 4 weeks but increasement of reed roots were not reduced. The difference of increasement of roots is due to a difference of propagation method. Sedge propagate by seed. Reed and commom reed propagate by seed and subterranean stem and reed has bigger subterranean stem than common reed. So increasement of common reed and sedge roots were slow than reed. By root growth pattern, increasement of pull-out capacity and shear resistance strength showed very similar way of root growth, those of common reed and sedge were fast in early stage of cultivation but were reduced. But increasement of pull-out capacity and shear resistance strength of reed was not reduced. A Maximum shear resistance strength called critical shear resistance strength of common reed and sedge can be Analyzed at 11 weeks after planted.