• Title, Summary, Keyword: 단면 치수

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Safety Analysis of the Flood Control of Urban River in Flash Flood (돌발홍수 발생시 도시하천의 치수안전도 분석)

  • Park, Ho-Sang;Sim, Ou-Bae;Song, Jai-Woo
    • Journal of Korean Society of Hazard Mitigation
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    • v.3 no.3
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    • pp.125-132
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    • 2003
  • In this study, safety analysis of river in flash flood due to local extraordinary rainfall was conducted for the Hong-Je river, which was selected as a representative sample basin because it is one of the most urbanized rivers in Seoul. The rainfall data of precipitation 310.1 mm and probable maximum precipitation (PMP) 740.0 mm in July $14{\sim}15$, 2001 was used to perform safety analysis. Resulting of safety analysis of the flood control in Hong-Je river, case of the 50 year of design frequency, safety section, management section, and danger section were represented to be 85%, 15%, and 0% respectively. For the 200 year of design frequency, safety section decreased by 6% and management section and danger section increment by 4% and 2%, respectively, The variation of management section was not observed with respect to 200 year of frequency. Little variation of safety value for management section for 300 and 500 of frequency increased by 8% and 12% relative to 50 year of frequency, respectively. management section and danger section for 1000 year of frequency increased by 19% and 13% relative to 50 year of frequency.

The size and shape optimization of plane trusses using the multi-levels method (다단계 분할기법에 의한 평면트러스의 단면치수 및 형상 최적화)

  • Pyeon, Hae-Wan;Oh, Kyu-Rak;Kang, Moon-Myung
    • Journal of Korean Society of Steel Construction
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    • v.12 no.5
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    • pp.515-525
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    • 2000
  • The purpose of this paper was to develop size & shape optimization programming algorithm of plane trusses. The optimum techniques applied in this study were extended penalty method of Sequential Unconstrained Minimization Techniques(SUMT) and direct search method with multi-variables proposed by Hooke & Jeeves. Upper mentioned two methods were used iteratively at each level of size and shape optimization routines. The design variables of size optimization were circular steel tube(structural member) diameter and thickness, those of shape optimization were joint coordinates, and the objective function was represented as total weight of truss. During the optimum design, two level procedures of size and shape optimization were interacted iteratively until the final optimum values were attained. At the previous studies about shape optimization of truss, the member sectional areas and coordinates were applied as design variables. So that they could not apply the buckling effect of compression member. In this paper, actual sizes of member and nodal coordinates are used as design variables to consider the buckling effect of compression member properly.

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Study on Hydration Properties of High Strength Mass Concrete to apply Precast Concrete (PC 적용을 위한 고강도 매스콘크리트의 수화특성에 관한 연구)

  • Park, Heung-Lee;Kim, Sung-Jin;Lee, Hoi-Keun;Lee, Seung-Hoon;Park, Byung-Keun;Jung, Sang-Jin
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.661-664
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    • 2008
  • As architectures have recently become high-risers and megastructured, stable high strength products have been ensured. Accordingly, use of precast concrete accouplement has been increased in order to facilitate air compression and rationalize construction. Since not only external heating but also internal temperature rise caused by the accumulation of cement hydration heat in manufacturing process, precast concrete members with large cross-section used for high-rise mega-structure's columns and beams may exhibit different temperature history compared to the precast concrete members for wall and sub-floor with relatively small cross-sections. Therefore, this study aims to elucidate the characteristics of temperature history of mass concrete members cast with high-strength concrete for precast concrete application. In this study, large cross-sectional precast concrete mock-up, unit cement quantity, and temperature histories in manufacturing precast concrete member under different curing condition were inclusively investigated.

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A Study on the Effects of Cross-sectional Dimension Change of Brake Pad Specimen on the Uncertainty of the Compressive Strength (제동 패드의 압축강도시편의 단면치수변화가 압축강도 불확도에 미치는 영향 분석)

  • Park, Soo Hong;Park, Jin Kyu;Kim, Si Wan;Park, Chan Kyoung
    • Journal of the Korean Society for Railway
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    • v.17 no.4
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    • pp.223-227
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    • 2014
  • The brake pad is one of the basic brake elements of a railway vehicle. It accomplishes braking action by friction between a pad and a brake disc. Because the brake pad must endure specified high pressure, the compressive strength is managed as the main performance factor. The standards for measuring the compressive strength of brake pads are KRS, KRCS, and KRT. These standards specify the size of the test piece for measuring compressive strength as $20mm{\times}10mm{\times}15mm$ ($W{\times}D{\times}H$). To reduce the uncertainty of the compressive strength, factors of uncertainty were analyzed. The results show that changing the dimensions of the cross section was useful to reduce the uncertainty. The uncertainty due to the new cross-sectional dimension shows the effectiveness of reducing uncertainty.

Optimum of Reinforced Concrete Framed Structures by Multilevel Decomposition (다단계분할법에 의한 철근콘크리트 뼈대구조의 최적화에 관한 연구)

  • 변근주;최홍식
    • Magazine of the Korea Concrete Institute
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    • v.1 no.1
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    • pp.87-94
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    • 1989
  • 철근콘크리트 뼈대구조와 같이 설계변수가 과다하고, 제약조건식이 복잡한 구조물의 최적화를 위하여는 구조물을 여러개의 부분구조물로 분할하여 최적해를 구하는 분할법이 많이 사용되고 있다. 그러나 기존의 분할법에 의한 최적화는 구조해석과정과 고정된 부재력에대한 단면설계변수의 부분최적화 과정만으로 이루어지기 때문에, 최적해를 구하려면 반복적인 재해석과정만을 수행하지 않으면 안된다. 따라서 본 연구에서는 다단계분할법에 의하여 철근콘크리트 뼈대구조의 최적화 문제를 3단계로 형성하고, 분할된 부분최적화문제의 최적화시 전체구조의 강성 및 부재력 변화가 반영되어 부분 구조물의 결합을 유지시킬 수 있는 최적화 알고리즘을 제안하였다. 최적화 문제에서 설계변수로는 단면의 크기, 철근량, 모멘트 재분배율등을 취하고,목적함수는 경비함수, 제약조건으로는 강도설계법에 의한 부재강도, 시방서의 요구사항등을 고려하여 문제를 형성하였다. 본 연구에서 개발한 다단계 최적화과정의 첫째 단계에서는 탄성해석에 의하여 재분배모멘트의 설계공간을 형성한다. 이 때 부재력변화량추정(forece approximation technique)에 의하여 단면치수의 변화에 따른 부재력의 변화를 제약조건식 내에 포함시킬 수 있도록 하였다. 둘째 단면에서는 첫째 단계에서 구한 부재력변화량추정이 포함된 제약조건식 내에서 무제약최소화기법에 의하여 단면치수를 최적화하도록 하였다. 셋째 단계에서는 재분배 모멘트를 최적화하였으며, 이 때 재분배모멘트의 변화에 따른 단면설계 변수의 변화는 둘째 단계에서 구한 설계민감도(design sensitivity)를 이용하여 반영시키도록 하였다. 제안된 알고리즘을 1층 2경간 및 2층 1경간 뼈대구조에 적용하여 알고리즘의 타당성과 효율성을 입증하였다. 따라서 본 연구의 알고리즘은 철근 콘크리트 뼈대구조의 최적설계에 안정성있게 적용할 수 있을 것으로 판단된다.

A Study on Size/Scale Effects in the Failure of Specially Orthotropic Slab Bridges (특별직교이방성 슬래브 교량의 파괴시 치수효과에 관한 연구)

  • Han, Bong-Koo;Kim, Duck-Hyun
    • Composites Research
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    • v.23 no.1
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    • pp.23-30
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    • 2010
  • Most of the bridge systems, including the girders, cross-beams, and concrete decks behave as specially orthotropic plates. In general, the analytical solution for such complex system is very difficult to obtain. In this paper presented, a design method of slab bridge of simple supported made by composite materials. For the design of bridge made by the composite materials, cross-section was used the form-core shape because of this shape is economical and profitable, and for output of the stress value used finite difference method. In this paper, the rate of tensile strength reduction due to increased size was considered. Strength-failure analysis procedure, using the reduced tensile strength, was presented. And also numerical study was made for these cases.

Transmission Characteristics on Dimensional Tolerances of Millimeter-Wave Rectangular Waveguides (밀리미터파용 구형 도파관의 단면 치수 변화에 의한 전송 특성)

  • Park, Kyung-Sik;Kim, Ki-Chai;Kang, Jin-Seob;Kim, Jeong-Hwan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.7
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    • pp.722-729
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    • 2013
  • This paper presents the influence on the transmission characteristics of dimensional tolerances of rectangular waveguides usually used as a low-loss transmission line in the millimeter-wave band. We derived the Green's functions of the waveguide with eigenfunction expansion method. The reflection coefficient of the waveguide with a post is calculated by using internal impedance in order to investigate the influence of dimensional tolerances of the waveguide. In order to check the validity of the theoretical analysis, the calculated reflection coefficients are compared with the measured results.

Size Optimization Design Based on Maximum Stiffness for Structures (구조물의 최대강성 치수최적설계)

  • Shin, Soo-Mi;Park, Hyun-Jung
    • Journal of the Korea Society of Computer and Information
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    • v.14 no.1
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    • pp.65-72
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    • 2009
  • This study presents a structural design optimizing sizes of high-rise steel plane truss members by maximizing stiffness subjected to given volume constraints. The sizing optimum design is evaluated by using a well-known optimality criteria (OC) of gradient-based optimization methods. In typical size optimization methods, truss structures are optimized with respect to minimum weight with constraints on the value of some displacement and on the member stresses. The proposed method is an inversed size optimization process in comparisons with the typical size optimization methods since it maximizes stiffness associated with stresses or displacements subjected to volume constraints related to weight. The inversed approach is another alternative to classical size optimization methods in order to optimize members' sizes in truss structures. Numerical applications of a round shape steel pipe truss structure are studied to verify that the proposed maximum stiffness-based size optimization design is suitable for optimally developing truss members's sizes.

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Optimal Section Design for Metal Press Door Impact Beam Development by 3-Point Bending Analysis (3점 굽힘 하중 해석을 통한 금속 판재형 도어 임팩트 단면형상 최적설계)

  • Kim, Sun-Yong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.7
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    • pp.166-172
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    • 2019
  • A case study was performed in order to develop well-designed of thin plate door impact beam. The conventional impact beam was consisted of steel-pipe welded two brackets on the both side, which causes low productivity and high cost. In order to overcome those disadvantage, it is necessary to develop a new type of door impact; thin plate impact beam. The thin plate impact beam was not needed a welding procedure, which can lead low cost and high productivity. In order to maximally resist from an external force, the cross-section design should be well designed. 6 different cross-section design were proposed based on engineer's experience. Three point bending test was simulated those 6 different impact beam and compared the reaction forces. Among them, one case was chosen and redesigned for detail design.

Dimensional Stability of Waterlogged Archaeological Wood in PEG, Lactitol and Sucrose Treatment (수침목재의 PEG, 락티톨, 슈크로오스 처리에 의한 치수안정화 효과)

  • Lee, Hyo Sun;Kang, Ae Kyung;Park, Sang Jin
    • Journal of Conservation Science
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    • v.8 no.1
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    • pp.28-32
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    • 1999
  • The performance of dimensional stabilization of lactitol, PEG (Mw, 4000), and sucrose was evaluated for thin sections of oak wood (Quercus sp.) that had been buried in underground for presumably 1500 years. Thin wood sections of the specimen were soaked for three and seven days in each stabilizing agent with wide concentration ranges of 10, 30, 50, and $70\%$ by weight. Sucrose showed the largest weight gain among three agents, and the shrinkage of cross sections were found to be $1\%\;and\;4\%$ for three and seven days soaking, respectively. The result showed that sucrose among three stabilizing agents used was the best for the dimensional stabilization of the oak wood.

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