• Title/Summary/Keyword: Structural Element

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Study of a "wing-type" implant on stress distribution and bone resorption at the alveolar crest

  • Park, Jong-Wook;Kim, Sin-Guen;Choi, Dong-Won;Choi, Mi-Ra;Yoon, Youn-Jin;Park, Jun-Woo;Choi, Dong-Ju
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.38 no.6
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    • pp.337-342
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    • 2012
  • Objectives: Implants connect the internal body to its external structure, and is mainly supported by alveolar bone. Stable osseointegration is therefore required when implants are inserted into bone to retain structural integrity. In this paper, we present an implant with a "wing" design on its area. This type of implant improved stress distribution patterns and promoted changes in bone remodeling. Materials and Methods: Finite element analysis was performed on two types of implants. One implant was designed to have wings on its cervical area, and the other was a general root form type. On each implant, tensile and compressive forces ($30N/m^2$, $35N/m^2$, $40N/m^2$, and $45N/m^2$) were loaded in the vertical direction. Stress distribution and displacement were subsequently measured. Results: The maximum stresses measured for the compressive forces of the wing-type implant were $21.5979N/m^2$, $25.1974N/m^2$, $29.7971N/m^2$, and $32.3967N/m^2$ when $30N/m^2$, $35N/m^2$, $40N/m^2$, and $45N/m^2$ were loaded, respectively. The maximum stresses measured for the root form type were $23.0442N/m^2$, $26.9950N/m^2$, $30.7257N/m^2$, and $34.5584N/m^2$ when $30N/m^2$, $35N/m^2$, $40N/m^2$, and $45N/m^2$ were loaded, respectively. Thus, the maximum stresses measured for the tensile force of the root form implant were significantly higher (about three times greater) than the wing-type implant. The displacement of each implant showed no significant difference. Modifying the design of cervical implants improves the strength of bone structure surrounding these implants. In this study, we used the wing-type cervical design to reduce both compressive and tensile distribution forces loaded onto the surrounding structures. In future studies, we will optimize implant length and placement to improve results. Conclusion: 1. Changing the cervical design of implants improves stress distribution to the surrounding bone. 2. The wing-type implant yielded better results, in terms of stress distribution, than the former root-type implant.

A Study on a Classical Construction Paradigm in Modern Fashion (현대 패션에 나타난 고전적 조형 패러다임에 관한 연구)

  • Kim Hye-Young;Lee Shin-Young
    • The Research Journal of the Costume Culture
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    • v.13 no.6 s.59
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    • pp.960-976
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    • 2005
  • Classicism pursued beauty comprised of a perfect form, and beauty was perceived as a state of sufficiency. Accordingly, a completed and permanent beauty was sought after; as a result, a perfect and flawless form became the mainstream, and there was an effort to visualize the eternal proportional perfection. In classicism, forms were perfectly embodied with systematic inevitability and absolute inflexibility, by which an extremely clear aspect appeared. This study analyzes a classical construction paradigm in modern fashion according to the five categories: 'Harmony and order by numerical proportion', 'Clear form', 'Simplification of form and two-dimensional Seh-form', 'Completed contracture structure', and 'Pluralistic unification', and the respective formative characteristics are as follows. First, in terms of the formative aspect of modern fashion,'Harmony and order by numerical proportion' results from thorough observance of extreme and golden section (proportion of 5 :8) which was an aesthetic standard of beautiful body in classicism. Second, 'Clear form' appears in clothes as individual clearness of structural elements expressing each part of body, and shows a well-established form possible to be grasped with equal and clear contour line. Third,'Simplification of form and two-dimensional Seh-form' comes out as form composition, single line, single layer structure, two-dimensional form and arrangement of elements of clothes through the front viewpoint caused by 2D diagramming work while fashion-designing and producing. Also, it is seen that two-dimensional proportion which is composed of sections through various harmonious lines and sides according to the simple two-dimensional compatibility principle is accomplished. Fourth, 'Completed contracture structure' emerges as an expression of stationariness, in other words, fixation of an overall impression. This is a tendency that the overall form is grasped as a fixedly intact shape without a big change of the silhouette of clothes. Fifth, 'Pluralistic unification' means that it respectively emphasizes all the parts composing clothes by making them individually independent at the same time as each element is inclusively shown with the harmony of the overall silhouette of clothes and many other details. This study examined classical formative characteristics through a theoretical research on a formative paradigm revealing the classical style. Also, the significance of classical or rational value of art was illuminated by observing what characteristics a classical formation paradigm shows in modern fashion. As a result, classical characteristics in modern fashion prove that classicism is not a merely past construction style separated from the present but a construction paradigm deeply involved in our reason system.

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Analysis and Design Theory of Aperture-Coupled Cavity-Fed Back-to-Back Microstrip Directional Coupler (개구면 결합 공진기 급전 마이크로스트립 방향성결합기 해석 및 설계)

  • Nam, Sang-Ho;Jang, Guk-Hyun;Nam, Kyung-Min;Lee, Jang-Hwan;Kim, Chul-Un;Kim, Jeong-Phill
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.3 s.357
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    • pp.7-17
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    • 2007
  • An analysis and design theory of an aperture-coupled cavity-fed back-to-back microstrip directional coupler is presented for the efficient and optimized design. For this purpose, an equivalent network is developed, and simple but accurate calculations of circuit element values are described. Design equations of the coupler are derived based on the equivalent circuit. In order to determine various structural design parameters, the evolutionary hybrid optimization method based on the genetic algorithm and Nelder-Mead method is invoked. As a validation check of the proposed theory and optimized design method, a 10 dB directional coupler was designed and fabricated. The measured coupling was 10.3 dB at 3 GHz, and the return loss and isolation were 31.8 dB and 30.5 dB, respectively. The directional coupler also showed very good quadrature phase characteristics. Good agreements between the measured and the design specifications fully validate the proposed network analysis and design procedure.

A Study on Unstable Phenomenon of Space Truss Structures Considering Initial Imperfection (트러스형 공간구조물의 초기 불완전을 고려한 불안정 현상에 관한 연구)

  • Lee, Jin-Hyouk;Baik, Tai-Soon;Shon, Su-Deok;Kim, Seung-Deog;Kang, Moon-Myung
    • Journal of Korean Association for Spatial Structures
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    • v.4 no.2 s.12
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    • pp.63-71
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    • 2004
  • The structural space is gradually wide and is wanting agreeable environment by the requirement and necessity of people who lives modem stage. The building coincides with such requirements and is the high rise building actual circumstances which is doing ultra-large. The confirmed report of the technology to organize great merit is becoming currently considerably important issue in constructing a building field. Thus, this paper examine closely for nonlinear unstable taking a picture uneasiness height of prosperity considering to initial imperfection by a numerical method with a space frame structure of discrete system in large space structure. Based on previous investigation method, this paper induce nodal stiffness matrix of solid truss elements considering geometrical nonlinear using finite element method. In this paper, three types of space structure considered; i) 1-free node space structure, ii) 2-free node space structure, iii) multi-free node space structure. It apply the above examples to a nonlinear program, next, grasp the characteristic of an unstable conduct and the result was a clearing low.

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Effect of the Member Joint on Structural Performance of an Arch-type Multi-span Greenhouse: A Full-scale Experimental and Numerical Study (부재 접합부가 아치형 연동온실의 구조 성능에 미치는 영향: 실대형 실험적 및 해석적 연구)

  • Choi, Man-kwon;Ryu, Hee-ryong;Cho, Myeong-whan;Yu, In-ho
    • Journal of Bio-Environment Control
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    • v.26 no.4
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    • pp.402-410
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    • 2017
  • The effect of the steel pipe member joint on the design performance of a plastic multi-span greenhouse was analysed through the comparing full-scale experiment and numerical analysis. The design performance of the greenhouse is generally evaluated through numerical analysis, but it is rare to consider the characteristics of the connections or joints of the members. In this study, the effect of the column-gutter beam-rafter-wind break wall joint on the design performance of the whole structure of a plastic multi-span greenhouse was analysed. The numerical results with assuming that the member joint are rigid condition were compared with the full-scale load test results using member joints used in the field. The stiffness of the entire structure was compared using the load-displacement relationship and the change of the load sharing ratio that the main members such as column, rafters, and wind break wall was analysed. The results of the load test were about 40% larger than the numerical result and the member stress was more than twice as large as those of the loaded columns. In order to increase the reliability of the design performance of the greenhouse, it is necessary to develop a numerical analysis model which can consider the characteristics of various joints.

Bearing resistance design of stainless steel bolted connections at ambient and elevated temperatures

  • Cai, Yancheng;Young, Ben
    • Steel and Composite Structures
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    • v.29 no.2
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    • pp.273-286
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    • 2018
  • In recent years, significant progress has been made in developing design rules for stainless steel members, while the investigation on bolted connections is relatively limited, in particular at elevated temperatures. In this paper, experimental and numerical investigations on stainless steel bolted connections at ambient and elevated temperatures from the literature were reviewed. Firstly, the research program that focused on structural behavior of cold-formed stainless steel (CFSS) bolted connections at elevated temperatures carried out by the authors were summarized. Over 400 CFSS single shear and double shear bolted connection specimens were tested. The tests were conducted in the temperature ranged from 22 to $950^{\circ}C$ using both steady state and transient state test methods. It is shown that the connection strengths decrease as the temperature increases in the similar manner for the steady state test results and the transient state test results. Generally, the deterioration of the connection strengths showed a similar tendency of reduction to those of the material properties for the same type of stainless steel regardless of different connection types and different configurations. It is also found that the austenitic stainless steel EN 1.4571 generally has better resistance than the stainless steel EN 1.4301 and EN 1.4162 for bolted connections at elevated temperatures. Secondly, extensive parametric studies that included 450 specimens were performed using the verified finite element models. Based on both the experimental and numerical results, bearing factors are proposed for bearing resistances of CFSS single shear and double shear bolted connections that subjected to bearing failure in the temperature ranged from 22 to $950^{\circ}C$. The bearing resistances of bolted connections obtained from the tests and numerical analyses were compared with the nominal strengths calculated from the current international stainless steel specifications, and also compared with the predicted strengths calculated using the proposed design equations. It is shown that the proposed design equations are generally more accurate and reliable than the current design rules in predicting the bearing resistances of CFSS (EN 1.4301, EN 1.4571 and EN 1.4162) bolted connections at elevated temperatures. Lastly, the proposed design rules were further assessed by the available 58 results of stainless steel bolted connections subjected to bearing failure in the literature. It is found that the proposed design rules are also applicable to the bearing resistance design of other stainless steel grades, including austenitic stainless steel (EN 1.4306), ferritic stainless steel (EN 1.4016) and duplex stainless steel (EN 1.4462).

Differentiation of Border Cells During Oogenesis in Drosophila melanogaster (노랑초파리 난자 형성과정 동안의 경계세포의 분화)

  • Gye, Myung-Chan;Cho, Kyoung-Sang;Lee, Chung-Choo
    • Development and Reproduction
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    • v.2 no.1
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    • pp.45-52
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    • 1998
  • An enhncer detector line(EDL) having P[1ArB] insertion in X chromosome with expression of reporter gene (lacZ) in the polar cells and border cell of egg chamber was established and used to monitor the differentiation and migration of border cells during the oogenesis of Drosophila. differentiation of border cell from the anterior polar follicle cells was evident in stage-9 egg chamber of EDL149 which was characterized by migration of columnar follicle cells toward posterior of egg chamber surrounding the oocyte. Migration of border cells was observed in the stage-9 and -10 egg chambers. \beta -galactosidase activities were rapidly increased during the first 4 days after eclosion, and it coincided with the timing of border cell differentiation in the ovary during adult life. Homozygote of EDL149 showed some retardation of border cell migration , resulting absence of migration of some border cells in the anterior part of egg chamber or delayed migration of some border cells in the stage-10 egg chamber. These results suggest that the P[1ArB] of EDL149 is inserted at the locus of the structural gene required for the border cell migration. In addition to the expression in egg chambers, lacZ expression was also detected in the meiotic germ cells of testis and antenna, suggesting the possible requirement of the trapped gene function in these organ. this EDL and enhancer trapped gene might be useful for the study of developmentally regulated cell migration.

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Prestressing Effect of LNG Storage Tank with 2,400 MPa High-Strength Strands (2,400 MPa급 고강도 강연선이 적용된 LNG 저장탱크의 프리스트레싱 효과)

  • Jeon, Se-Jin;Seo, Hae-Keun;Yang, Jun-Mo;Youn, Seok-Goo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.36 no.6
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    • pp.999-1010
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    • 2016
  • High-strength strands have been increasingly applied to recent actual structures in Korea. Structural effect of the increased spacing of sheaths was investigated in this study when the usual 1,860 MPa strands of an LNG storage tank are replaced with 2,400 MPa high-strength strands. First, finite element models of a cylindrical wall of an LNG tank were established and prestressing effect of the circumferential and vertical tendons was considered as equivalent loads. As a result of varying the tendon spacing and prestressing force with the total prestressing effect kept the same, the stress distribution required in design was obtained with the high-strength strands. Also, a full-scale specimen that corresponds to a part of an LNG tank wall was fabricated with 31 high-strength strands with 15.2 mm diameter inserted in each of two sheaths. It was observed that such a high level of prestressing force can be properly transferred to concrete. Moreover, an LNG tank with the world's largest 270,000 kl capacity was modeled and the prestressing effect of high-strength strands was compared with that of normal strands. The watertightness specifications such as residual compressive stress and residual compression zone were also ensured in case of leakage accident. The results of this study can be effectively used when the 2,400 MPa high-strength strands are applied to actual LNG tanks.

Hydrodynamic Analysis of Submerged Floating Tunnel Structures by Finite Element Analysis (유한요소해석을 통한 해중터널의 유체동역학 해석)

  • Kim, Seungjun;Park, Woo-Sun;Won, Deok-Hee
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.36 no.6
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    • pp.955-967
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    • 2016
  • As transportation systems for connecting lands and islands, oversea long-span bridges, underwater tunnels, and immersed tunnels have been mainly used so far. Submerged floating tunnels (SFTs) moored under specific water depth are one of the newest oversea transportation system. Compared to other existing systems, the new system requires relatively less construction cost and time. But, there is still no construction example. For reasonable design of the tunnel and mooring lines the rational structural analysis should be firstly performed. Unlike common transportation structures, the submerged tunnels are mainly affected by the wave, vary irregular excitation component. So, the analysis scheme might be difficult because of the characteristics of the submerged structures. This study aims to suggest the rational global performance analysis methodology for the submerged tunnels. Using ABAQUS the dynamic response of the experimental models studied by KIOST (2013) was investigated considering regular waves. By comparing the simulation results with the experimental results, the feasibility of the numerical simulation was verified. Using the suggested method, the effects of initial inclination of the tethers and draft of the tunnel on the dynamic behavior were studied. In addition, dynamic response of a SFT under the irregular wave was examined.

Structural Study on Dance Story-Telling (무용의 스토리텔링 구조연구)

  • Kim, Ki-Hwa;Baek, Hyun-Soon
    • The Journal of the Korea Contents Association
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    • v.12 no.1
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    • pp.265-274
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    • 2012
  • This study aims to examine the physical language of dance art's acceptability of the discourse method of story-telling as a narrative discourse system from the view of story-telling of cultural contents. Dance, through the establishment of relationship between dancers and stage art, can form a discourse system with various literary devices including figures of speech, metaphors, and symbols. The argument over manifestation of dance's narrative components in the concept of story-telling is shown as follows; the background as an object can offer time and spatial backgrounds through stage art and the dancers' performance elements; and, for the character, the dancer himself can be the first-person-narrator and possibly makes plane personality descriptions. As for the elements of main affairs of dance, the stage art components present the background of primary motif of incident and the dancer's diverse relationships form conflicts through the correlation of solo dance, duet, and group dance. The plot as a process of developing the main affair is led by actant such as the dancer's mime actions, gestures, facial expressions, etc. The element of dance's revealing narration is the dance art itself and the developing structure of narration is the dance language's own grammar. Choreographers should compose persuasive dance texts to convey stories efficiently through character decisions, their actions, stage art's elements that display the time and spatial backgrounds, and the development of plot, as a narrative discourse of dance.