• Title/Summary/Keyword: hinge

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Mechanical behaviour of waterway culvert structure assembled by precast segments (프리캐스트 세그먼트를 이용한 조립식 수로암거구조물의 역학적 거동 특성)

  • Lee, Gyu-Phil;Hwang, Jae-Hong;Shin, Hyu-Sung;Hong, Se-Kyun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.12 no.2
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    • pp.193-200
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    • 2010
  • Due to the characteristic of culvert structure, the standard section of the culvert has been established and applied in field. However, this becomes a limitation in selecting a section design corresponding to various field conditions although it can improve the design and applicability of culvert structure. In order to overcome this limitation, we have developed the design and application technology of culvert structure corresponding to the field conditions that various shapes of culvert structure can be covered by assembly of precast segments. Because the structural characteristics of assembling-type waterway culvert structure, the thickness of structure and amount of reinforcing rods can vary according to the fixation or internal hinge status in the connection part of precast segments. This has a strong influence on the applicability and economic efficiency of culvert structure. Accordingly, in order to suggest a reasonable modeling technique of segment connection parts, this study has conducted the field experiment and numerical analysis. According to the results of field experiment and numerical analysis, the slab, wall and base slab with mortar splice sleeves have shown that the assembling-type of waterway culvert structure behaves like an integrated structure.

Evaluation of Flexural Ductility of Negative Moment Region of I-Girder with High Strength Steel (고강도 강재 적용 I-거더의 부모멘트부 휨연성 평가)

  • Joo, Hyunsung;Moon, Jiho;Choi, Byung-Ho;Lee, Hak-Eun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.6A
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    • pp.513-523
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    • 2010
  • For continuous I-girder bridges, a large negative bending moment is generated near pier region so that plastic hinge is first formed at this point. Then, the bending moment is redistributed when the I-girder has enough flexural ductility (or rotational capacity). However, for I-girder with high strength steel, it is known that the flexural ductility is considerably decreased by increasing the yield strength of material. Thus, it is necessary to conduct a study for guaranteeing proper flexural ductility of I-girder with high-strength steel. In this study, the evaluation of flexural ductility of negative moment region of I-girder with high strength steel where yield stress of steel is 680 MPa is presented based on the results of finite element analysis and experiment. From the results, it is found that the flexural ductility of the I-girder is significantly reduced due to the increase of elastic deformation and the decrease of plastic deformation ability of the material when the yield strength increases. In this study, the method to improve the flexural ductility of I-girder with high strength steel is proposed by an unequal installation of cross beam and an optimal position of cross beam is also suggested. Finally, the effects of the unequal installation of cross beam on the flexural ductility are discussed based on the experimental results.

Development of a Structural-Analysis Model for Blast-Resistant Design of Plant Facilities Subjected to Vapor-Cloud Explosion (증기운 폭발을 받는 플랜트 시설물의 내폭설계를 위한 구조 해석 모델 개발)

  • Bo-Young Choi;Seung-Hoon Lee;Han-Soo Kim
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.37 no.2
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    • pp.103-110
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    • 2024
  • In this study, a nonlinear dynamic analysis of a frame and single member, which reflect the characteristics of a plant facility, is performed using the commercial MIDAS GEN program and the results are analyzed. The general structural members and material properties of the plant are considered. The Newmark average-acceleration numerical-analysis method is applied to a plastic hinge to study material nonlinearity. The blast load of a vapor-cloud explosion, a representative plant explosion, is calculated, and nonlinear dynamic analysis is conducted on a frame and single member. The observed dynamic behavior is organized according to the ratio of natural period to load duration, maximum displacement, ductility, and rotation angle. The conditions and range under which the frame functions as a single member are analyzed and derived. NSFF with a beam-column stiffness ratio of 0.5 and ductility of 2.0 or more can be simplified and analyzed as FFC, whereas NSPF with a beam-column stiffness ratio of 0.5 and ductility of 1.5 or more can be simplified and analyzed as FPC. The results of this study can serve as guidelines for the blast-resistant design of plant facilities.

Sturctural Geometry of the Pyeongchang-Jeongseon Area of the Northwestern Taebaeksan Zone, Okcheon Belt (옥천대 북서부 태백산지역 평창-정선일대 지질구조의 기하학적 형태 해석)

  • Jang, Yirang;Cheong, Hee Jun
    • Economic and Environmental Geology
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    • v.52 no.6
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    • pp.541-554
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    • 2019
  • The Taebaeksan Zone of the Okcheon Belt is a prominent fold-thrust belt, preserving evidence for overlapped polyphase and diachronous orogenic events during crustal evolution of the Korean Peninsula. The Pyeongchang-Jeongseon area of the northwestern Taebaeksan Zone is fault-bounded on the western Jucheon and southern Yeongwol areas, showing lateral variations in stratigraphy and structural geometries. For better understanding these geological characteristics of the northwestern Taebaeksan Zone, we have studied the structural geometry of the Pyeongchang-Jeongseon area. For this, we have firstly carried out the SHRIMP U-Pb age analysis of the age-unknown sedimentary rock to clarify stratigraphy for structural interpretation. The results show the late Carboniferous to middle Permian dates, indicating that it is correlated to the Upper Paleozoic Pyeongan Supergroup. In addition to this, we interpreted the geometric relationships between structural elements from the detailed field investigation of the study area. The major structure of the northwestern Taebaeksan Zone is the regional-scale Jeongseon Great syncline, having NE-trending hinge with second-order folds such as the Jidongri and Imhari anticlines and the Nambyeongsan syncline. Based on the stereographic and down-plunge projections of the structureal elements, the structural geometry of the Jeongseon Great syncline can be interpreted as a synformal culmination, plunging slightly to the south at its southern area, and north at the northern area. The different map patterns of the northern and southern parts of the study area should be resulted in different erosion levels caused by the plunging hinges. Considering the Jeongseon Great syncline is the major structure that constrains the distribution of the Paleozoic strata of the Pyeongchang and Jeongseon areas, the symmetric repetition of the lower Paleozoic Joseon Supergroup in both limbs should be re-examined by structural mapping of the Hangmae and Hoedongri formations in the Pyeongchang and Jeongseon areas.

Geological Structure and Deformation History in the Gwangju area, Gyeonggi-do, Korea (경기도 광주시 일대의 지질구조와 변형사)

  • Lee Hee-Kwon;Kim Man-Kwang
    • The Journal of the Petrological Society of Korea
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    • v.14 no.2 s.40
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    • pp.108-115
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    • 2005
  • Gyeonggi metamorphic complex in the Gwangju area include banded biotite gneiss and quartzofeldspathic gneiss. Detailed structural analysis suggests that structural elements in the study area were formed by at least five phase of deformations. Penetrative compositional foliations(S1) formed in the banded gneiss during the first metamorphism and deformation (D1). After intrusion of plutonic rocks, the second deformation (D2) produced S2 foliations in the banded gneiss and quartzofeldspathic gneiss during the second metamorphism. D3 structures are represented by isoclinal folds (F3) whose axial surfaces are parallel to S3 foliations. The N-S oriented shortening (D4) was accommodated by closed upright F4 fold with about 100m of axial surface separation. F4 fold is refolded by regional F5 folding resulting in different orientation and fold style of F4 fold according to the position of F5 fold. The F4 fold with tight interlimb angle is subparallel to the axial surface (north-south) of F5 fold in the core of the F5 fold. In contrast the F4 fold trends northeast in the western limb and northwest in the eastern limb of F5 fold. The interlimb angle is larger in the limbs than that in the core of F5 fold. The trace of foliations is constrained by mainly F4 and F5 folds. Joint fanning around fold is developed in the limbs of F5 fold and bc joints are dominant in the hinge area of F5 fold. A strike-slip fault had developed in tile central part of the study area after F5 folding. The orientation of joint and foliation is rotated anticlockwise about $15^{\circ}$ by the landslide occurred during the Quaternary.

On the penecontemporaneous deformation structures of the Sinri area at the mid western boundary of the Jinan Basin (진안분지 서변 중앙부 신리지역의 준퇴적동시성 변형구조)

  • Lee Young-Up
    • The Korean Journal of Petroleum Geology
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    • v.6 no.1_2 s.7
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    • pp.8-19
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    • 1998
  • In the Sinri area located at the mid western boundary of the Jinan basin, the Manduksan Formation which mainly consists of coarse sandstone narrowly intercalated with shale and the alternation of sand and shale and the Dalgil Formation mainly of shale are distributed. It consists of four lithofacies, such as coarse sandstone, interbedded sandstone/shale, shale and volcanic rock lithofacies. All sediments are interpreted to be deposited by turbidity currents and free fallouts in a lacustrine basin. In these rocks many penecontemporaneous defomation structures are observed such as fold and thrust fault at large scale, and swelling, boudin structure, flame structure, load structure, ptygmatic fold and convolute bedding at small scale. All these structures are developed between upper and lower undisturbed sedimentary strata. Two large folds are similar folds, but lower one gradually developed into concentric shape. The swelling structures by convergence of the sediments are observed in the hinge area and the boudin structures are developed in the limb. The thrust faults including minor folds and sandstone lobes show duplex structure with asymmetric and kink fold on and below in front of the detached sandstone layer. Development of the swellings, boudins and lobes indicates the flexbility of the sediments during deformational episodes. The folds and thrust faults rarely contain fractures relative their scales and lithologies. This feature also indicates the retrievability of sediments during deformation. At the flanks of the thrust faults the normal faults are formed contemporaneously. The deformation structures at small scale such as flame structures, load structures, ptygmatic folds and convolute beddings are syndepositional and penecontemporaneous, which show the effects of tectonic movements. All these deformed sedimentary structures of the Sinri area suggest the continuing tectonic movements during and/or after deposition.

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Object Tracking Based on Exactly Reweighted Online Total-Error-Rate Minimization (정확히 재가중되는 온라인 전체 에러율 최소화 기반의 객체 추적)

  • JANG, Se-In;PARK, Choong-Shik
    • Journal of Intelligence and Information Systems
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    • v.25 no.4
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    • pp.53-65
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    • 2019
  • Object tracking is one of important steps to achieve video-based surveillance systems. Object tracking is considered as an essential task similar to object detection and recognition. In order to perform object tracking, various machine learning methods (e.g., least-squares, perceptron and support vector machine) can be applied for different designs of tracking systems. In general, generative methods (e.g., principal component analysis) were utilized due to its simplicity and effectiveness. However, the generative methods were only focused on modeling the target object. Due to this limitation, discriminative methods (e.g., binary classification) were adopted to distinguish the target object and the background. Among the machine learning methods for binary classification, total error rate minimization can be used as one of successful machine learning methods for binary classification. The total error rate minimization can achieve a global minimum due to a quadratic approximation to a step function while other methods (e.g., support vector machine) seek local minima using nonlinear functions (e.g., hinge loss function). Due to this quadratic approximation, the total error rate minimization could obtain appropriate properties in solving optimization problems for binary classification. However, this total error rate minimization was based on a batch mode setting. The batch mode setting can be limited to several applications under offline learning. Due to limited computing resources, offline learning could not handle large scale data sets. Compared to offline learning, online learning can update its solution without storing all training samples in learning process. Due to increment of large scale data sets, online learning becomes one of essential properties for various applications. Since object tracking needs to handle data samples in real time, online learning based total error rate minimization methods are necessary to efficiently address object tracking problems. Due to the need of the online learning, an online learning based total error rate minimization method was developed. However, an approximately reweighted technique was developed. Although the approximation technique is utilized, this online version of the total error rate minimization could achieve good performances in biometric applications. However, this method is assumed that the total error rate minimization can be asymptotically achieved when only the number of training samples is infinite. Although there is the assumption to achieve the total error rate minimization, the approximation issue can continuously accumulate learning errors according to increment of training samples. Due to this reason, the approximated online learning solution can then lead a wrong solution. The wrong solution can make significant errors when it is applied to surveillance systems. In this paper, we propose an exactly reweighted technique to recursively update the solution of the total error rate minimization in online learning manner. Compared to the approximately reweighted online total error rate minimization, an exactly reweighted online total error rate minimization is achieved. The proposed exact online learning method based on the total error rate minimization is then applied to object tracking problems. In our object tracking system, particle filtering is adopted. In particle filtering, our observation model is consisted of both generative and discriminative methods to leverage the advantages between generative and discriminative properties. In our experiments, our proposed object tracking system achieves promising performances on 8 public video sequences over competing object tracking systems. The paired t-test is also reported to evaluate its quality of the results. Our proposed online learning method can be extended under the deep learning architecture which can cover the shallow and deep networks. Moreover, online learning methods, that need the exact reweighting process, can use our proposed reweighting technique. In addition to object tracking, the proposed online learning method can be easily applied to object detection and recognition. Therefore, our proposed methods can contribute to online learning community and object tracking, detection and recognition communities.

Cyclic Seismic Testing of Cruciform Concrete-Filled U-Shape Steel Beam-to-H Column Composite Connections (콘크리트채움 U형합성보-H형강기둥 십자형 합성접합부의 내진성능)

  • Park, Chang-Hee;Lee, Cheol-Ho;Park, Hong-Gun;Hwang, Hyeon-Jong;Lee, Chang-Nam;Kim, Hyoung-Seop;Kim, Sung-Bae
    • Journal of Korean Society of Steel Construction
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    • v.23 no.4
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    • pp.503-514
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    • 2011
  • In this research, the seismic connection details for two concrete-filled U-shape steel beam-to-H columns were proposed and cyclically tested under a full-scale cruciform configuration. The key connecting components included the U-shape steel section (450 and 550 mm deep for specimens A and B, respectively), a concrete floor slab with a ribbed deck (165 mm deep for both specimens), welded couplers and rebars for negative moment transfer, and shear studs for full composite action and strengthening plates. Considering the unique constructional nature of the proposed connection, the critical limit states, such as the weld fracture, anchorage failure of the welded coupler, local buckling, concrete crushing, and rebar buckling, were carefully addressed in the specimen design. The test results showed that the connection details and design methods proposed in this study can well control the critical limit states mentioned above. Especially, the proposed connection according to the strengthening strategy successfully pushed the plastic hinge to the tip of the strengthened zone, as intended in the design, and was very effective in protecting the more vulnerable beam-to-column welded joint. The maximum story drift capacities of 6.0 and 6.8% radians were achieved in specimens A and B, respectively, thus far exceeding the minimumlimit of 4% radians required of special moment frames. Low-cycle fatigue fracture across the beam bottom flange at a 6% drift level was the final failure mode of specimen A. Specimen B failed through the fracture of the top splice plate of the bolted splice at a very high drift ratio of 8.0% radian.

Conservation and Reproduction of Cheongpung Buwongun Kim Wumyeong's Funeral Bier (청풍부원군 김우명 상여의 보존 및 복제)

  • Jeong, Jaeung;Huh, Ilkwon;Park, Seungwon;Yi, Yonghee
    • Conservation Science in Museum
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    • v.14
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    • pp.91-113
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    • 2013
  • Cheongpung Buwongun Kim Wu-myeong's Funeral Bier, an important folklore cultural property No.120, possessed by Chuncheon National Museum was donated in 2002 (by Kim Seonggu). It consists of a bier, yoyeo(腰輿), myeongjeongdae(銘旌臺), and manjangdae(輓章臺). It has a high value as the oldest royal bier. The bier which had a resting time in the storage for special exhibition of "The great cultural treasure of Gangwon province" was inspected in September 2012 and colored pigment layer of the wooden part had the risk of peeling off and surface damage of the textile was serious. Therefore, conservation treatment was conducted. In addition, knots and susiks(垂飾) were severely damaged and their exhibition was impossible. Therefore, a reproduction to replace them through a close investigation was made. All parts of the funeral bier were in separation except for the basic furniture. Conservation was made by dividing the parts into wooden parts and textile parts. Yoyeo was reinforced after disassembling bujae from it and then was reassembled. Paraloid B-72 2 wt% (in ethyle acetate), acrylic resin, was applied to the wooden part of the bier in order to reinforce the colored pigment layer with the addition of sodium alginate 2 wt%(in stilled water) and glue 4 wt%(in stilled water). The pollutants on the surface of the textile part were removed (vacuuming) and its creases were smoothed out (steaming). Fat-soluble pollutants were removed using an nonionic surfactant(Saponin, concentration at 0.25 to 0.5 g/𝑙, in de-ionized water). After the disassembly of the yoyeo from the broken wooden, it was bonded with glue (3 wt% for the first gluing, 35 wt% for gluing), and pine wood was used to restore missing parts. In the process of connecting Wongak(雲角), the original metal hinge and nails were reused to complete the assembly.

4D Printing Materials for Soft Robots (소프트 로봇용 4D 프린팅 소재)

  • Sunhee Lee
    • Fashion & Textile Research Journal
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    • v.24 no.6
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    • pp.667-685
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    • 2022
  • This paper aims to investigate 4D printing materials for soft robots. 4D printing is a targeted evolution of the 3D printed structure in shape, property, and functionality. It is capable of self-assembly, multi-functionality, and self-repair. In addition, it is time-dependent, printer-independent, and predictable. The shape-shifting behaviors considered in 4D printing include folding, bending, twisting, linear or nonlinear expansion/contraction, surface curling, and generating surface topographical features. The shapes can shift from 1D to 1D, 1D to 2D, 2D to 2D, 1D to 3D, 2D to 3D, and 3D to 3D. In the 4D printing auxetic structure, the kinetiX is a cellular-based material design composed of rigid plates and elastic hinges. In pneumatic auxetics based on the kirigami structure, an inverse optimization method for designing and fabricating morphs three-dimensional shapes out of patterns laid out flat. When 4D printing material is molded into a deformable 3D structure, it can be applied to the exoskeleton material of soft robots such as upper and lower limbs, fingers, hands, toes, and feet. Research on 4D printing materials for soft robots is essential in developing smart clothing for healthcare in the textile and fashion industry.