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Experimental Study on the Development of Void Precast Concrete Slab using Rubber Tube Mold for Inner Core (고무튜브 몰드 프리캐스트 콘크리트 유공 슬래브 개발에 관한 실험적 연구)

  • Bae, Kyu-Woong;Hong, Sung-Yub
    • Journal of the Korea Institute of Building Construction
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    • v.21 no.4
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    • pp.293-303
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    • 2021
  • The void PC slab has a structurally reasonable cross-section by forming the hollow section of the neutral axis that is unnecessary for bending behavior. Domestic PC factories have introduced automation equipment to produce hollow PC slabs, and are achieving hollow sections through inserts. However, since the excessive initial investment cost of the PC factory is the main factor in the increase in production cost, other alternatives are needed. Therefore, in this study, when producing hollow PC slab members, by using a rubber tube as a formwork to form an internal hollow space, it is intended to contribute to securing productivity through molding various hollow shapes, making it larger, lightweight, and enabling rapid production. To implement a hollow PC slab using a rubber tube mold, the shape of a hollow cross-section in which the tube is combined was implemented by considering the shape of the rubber tube first. In addition, to secure the concrete quality of the hollow part, the finish properties of the rubber tube mold and concrete were evaluated, and the hollow PC production process was established.

Root Development end Branching farms of Norway Spruce(Picea abies) in the Differently Acidified Forest Soil (토양(土壤) 산성화(酸性化) 정도(程度)에 따른 독일가문비나무(Picea abies)의 뿌리 발달(發達)과 분지형태(分枝形態)에 관(關)한 연구(硏究))

  • Lee, Do-Hyung
    • Journal of Korean Society of Forest Science
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    • v.90 no.4
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    • pp.458-464
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    • 2001
  • In this study, the annual growth of roots and their branching forms of Norway spruce(Picea abies [L.] Karst.) were analysed to compare the development of their root in the differently acidified forest soils. And there was no significant difference among the stands for the modified roots and the non-modified roots depending on the root branch forms, and however in the most acidified Weidenbrunnen stand, the modified roots, the abnormal root branch form such as fork, gun and rake types were appeared. As a result of the ring of the root, the annual horizontal root growth were 6.3cm for Weidenbrunnen and Barbis stands and 9.5cm for Eberg$\ddot{o}$tzen stand. The average annual vertical root growth was 4.4cm, 5.4cm, and 6.7cm for Weidenbrunnen stand, Barbis stand, and Eberg$\ddot{o}$tzen stand, respectively. The cross section area by root distribution at 80cm deep showed that the thick and thin roots were evenly distributed in of Eberg$\ddot{o}$tzen stand and the sum of root cross section area was $32.6cm^2$. In Barbis stand, the thick roots were distributed in the center while the thin roots were comparatively rare. And the sum of root cross section area was $29.2cm^2$. In Weidenbrunnen stand, only a few thin roots were found, and the total root cross section area was $10.9cm^2$. The stability coefficient of roots were in the order of Eberg$\ddot{o}$tzen stand(1.04), Barbis stand (0.3), and Weidenbrunnen(0.08) stand. Among the investigated Norway spruce stands, the modified abnormal root branching form and the low root growth appeared in the Weidenbrunnen stand could be attributed by the soil acidification etc.

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Three-Dimensional Analysis of the Shapes of Gathered Skirts (개더스커트 형상프로포션의 3차원적 해석)

  • Lee, Myung-Hee;Jung, Hee-Kyeong
    • Journal of the Korean Society of Clothing and Textiles
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    • v.30 no.11 s.158
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    • pp.1598-1607
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    • 2006
  • The purpose of this study was to analyze the proportion of gathered skirts using a three-dimensional measurement system. And in this experiment, we have attempted to accumulate three-dimensional data of wearing model and find out adequate methods for analyzing shape of clothes. The experimental design consists of two factorial designs. We established three different kinds of fabrics, ratio of gathers. The measurement tool for three-dimensional model was whole body 3D scanner(Exima-WBS2H). Analysis program used in experiment is RapidForm 2004 PP1 and Pattern Design 2000. Data analysis utilizes SPSS WIN 10.0 Package. As the results show, there were different effect of gather and proportion of shapes among the measurements of width, thickness and areas made by different lines of vision in cross-sectional silhouette. And there were difference shapes of section area at each part of gathered skirts between vertical-outline silhouette and vortical-plane silhouette made by gathering conditions. And also the cross-sectional silhouettes and vertical silhouettes were related to shape of clothes.

Practical resolution of angle dependency of multigroup resonance cross sections using parametrized spectral superhomogenization factors

  • Park, Hansol;Joo, Han Gyu
    • Nuclear Engineering and Technology
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    • v.49 no.6
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    • pp.1287-1300
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    • 2017
  • Based on the observation that ignoring the angle dependency of multigroup resonance cross sections within a fuel pellet would result in nontrivial underestimation of the spatial self-shielding of flux, a parametrized spectral superhomogenization (SPH) factor library (PSSL) method is developed as a practical means of resolving the problem. Region-wise spectral SPH factors are calculated by the normal and transport corrected SPH iterations after ultrafine group slowing down calculations over various light water reactor pin-cell configurations. The parametrization is done with fuel temperature, U-238 number density, fuel radius, moderator source represented by ${\Sigma}_{mod}V_{mod}$, and the number density ratio of resonance nuclides to that of U-238 in a form of resonance interference correction factors. The parametrization is successful in that the root mean square errors of the interpolated SPH factors over the fuel regions of various pin-cells are within 0.1%. The improvement in reactivity error of the PSSL method is shown to be superior to that by the original SPH method in that the reactivity bias of -200 pcm to -300 pcm vanishes almost completely. It is demonstrated that the environment effect takes only about 4% in the reactivity improvement so that the pin-cell based PSSL method is effective in the assembly problems.

Transverse Shear Behavior of Thin-Walled Composite Beams with Closed Cross-Sections (폐쇄형 단면을 갖는 박벽 복합재료 보의 전단변형 거동 해석)

  • Park, Il-Ju;Jung, Sung-Nam
    • Composites Research
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    • v.19 no.5
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    • pp.1-6
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    • 2006
  • In this study, a closed-form analysis has been developed for the transverse shear behavior of thin-walled composite beams with closed cross-sections. The shear flow distributions and cross-section stiffness coefficients are derived analytically by using a mixed beam approach. The theory has been applied to single-celled composite box-beams with elastic couplings. The location of the shear center and the effect of transverse shear deformation on the static behavior of composite beams are investigated in the framework of the analysis. The present results are validated against those of a two-dimensional finite element analysis and a good correlation has been obtained for box-beam cases considered in this study.

Three Dimensional Correction Factors for the Added Mass in the Horizontal Vibration of Ships (선체수평진동(船體水平振動)에 있어서의 부가질량(附加質量) 3차원수정계수(次元修正係數))

  • K.C.,Kim;B.K.,Yoo
    • Bulletin of the Society of Naval Architects of Korea
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    • v.11 no.1
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    • pp.9-16
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    • 1974
  • To contribute towards more accurate estimation of the virtual inertia coefficient for the horizontal vibration of ships, three dimensional correction factor $J_H$ for the added mass of finitely long elliptic prismatic bars in horizontal vibration in a free surface of an ideal fluid are calculated. In the problem formulation Dr. T. Kumai's quasi-finite length concept[1,11,12] is employed. Now that, in Dr. Kumai's work[1] for the horizontal vibration the mathematical model was a circular cylinder, the principal aim of the authors' work is to investigate the influence of the beam-draft ratio B/T on $J_H$. The numerical results of this work are shown in Fig.3 graphically, from which we may recognize that the influence of B/T on $J_H$ is remarkable as much as that of the length-draft ratio L/T(refer to Fig.1 also). In Fig.3 the curves for B/T=2.00 are of those based on Dr. Kumai's result[1]. On the other hand, the experimental data obtained by Burril et al.[9] for the horizontal vibration of finitely long prismatic bars of various cross-section shapes are compared with the theoretical added mass coefficients defined by combination of the authors' $J_H$ from Fig.3 and two dimensional coefficients $C_H$ obtained by Lewis form approximation for the corresponding sections. They are in reasonable correspondence with each other as shown in Fig.2. Finally, considering that the longitudinal profile of full-form ship's hull is well resembled to that of an elliptic cylinder and that the influences of other factors such as the sectional area coefficient and the shape of section contour itself can be well merged in the two dimensional added mass coefficient, the authors recommend that the data given in Fig.3 may be successfully adopted for the three dimensional correction factor the added mass in the horizontal vibration of hull-form ships.

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Failure Strength Analysis of Simply Supported Sandwich Slab Bridges made by Composite Materials (복합재료로 만들어진 단순지지 샌드위치 슬래브 교량의 파괴강도해석)

  • Han, Bong-Koo;Kim, Se-Won
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.11 no.1
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    • pp.77-84
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    • 2007
  • In this paper presented, a design method of sandwich slab bridge of simple supported made by composite materials. Many of the bridge systems, including the girders and cross-beams, and concrete decks behave as the special orthotropic plates. Such systems with sections, boundary conditions other than Navier or Levy solution types, or with irregular cross sections, analytical solution is very difficult to obtain. Thus, Finite Difference Method is used for analysis of the pertinent problem. For the design of bridge made by the composite materials, cross-section is used the form-core shape because of this shape is economical and profitable, and for output of the stress value used F.D.M. Based the experimental of a composite specialist, an equation expressing the rate of decrease of tensile strength of glass fibers based on increase of mass was obtained. From these equations, one can estimate the rate of tensile strength reduction due to increased size. Tasi-Wu failure criterion for stress space is used. Strength-failure analysis procedure, using these reduced tensile strength, is presented.

Observation of Papillary Tubercles on the Capsule of Swine Spleen : II. Histological Stuctures of Papillary Tubercles (돼지 비장표면(脾臟表面)의 유두양(乳頭樣) 결절(結節)에 관한 관찰(觀察) : II. 유두양(乳頭樣) 결정(結節)의 조직학적(組織學的) 구조(構造))

  • Kwak, Soo-dong
    • Korean Journal of Veterinary Research
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    • v.26 no.2
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    • pp.195-199
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    • 1986
  • The papillary tubercles (PTs) developed on the splenic capsule of normal Landrace pigs were collected and their histological structures were observed with light microscope. The results were summarized as follows : 1. The external features of the PTs were smooth spherical or oval form protruded on the splenic capsules. On cross section of PTs, the shapes were predominantly round or elliptical single follicular form, and were often multifollicular and irregular form in some PTs. 2. The PTs were interposed into the splenic capsule. Therefore the peripheral boundary of PT was consisted of splenic capsular tissue and this tissue was covered with mesothelium, The basal tissues of PT were consisted of thick connective tissue and smooth muscle of splenic capsule, and capsular foramen for transport tract between splenic parenchyma and the PT was found at the center of the basal boundary of PT. 3. The basal region of PT was composed of parenchyma and this tissue was the splenic red pulp but the central and peripheral regions of PT contained much more erythrocytes than in the splenic parenchymae. 4. The splenic parenchymae adjoining to PT contained more erythrocytes than in other splenic parenchymal regions and parallel fixed cells directed to the capsular foramen.

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Study of Hull Form Development and Resistance Performance of Catamaran-type High Speed Fishing Leisure Boat (고속 쌍동형 낚시 레저보트 선형개발과 저항성능에 관한 연구)

  • Jeong, Uh-Cheul;Kwon, Soo-Yeon;Choi, Ji-Hoon;Kim, Do-Jung;Hong, Ki-Sup
    • Journal of Ocean Engineering and Technology
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    • v.27 no.6
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    • pp.1-6
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    • 2013
  • A 25ft class fishing leisure boat is developed, and the resistance performances are investigated by a model test in a high-speed circulating water channel. The design speed of the developed ship is 25 knots using a 150 ps outboard engine. A catamanan type hull form using a planing section is adopted considering the Froude number and large deck area. The effect of a center body attached on the bottom of the cross deck is studied under various conditions. Wave patterns are observed to make clear the relationship between the resistance performance and the wave characteristics. The results show that the shape of the center body and the position of the chine line can have a strong effect on the resistance performance in a certain velocity range.

Hydraulic Assessment about Correlation of Fluvial Movement and River Bed Form on the Narrow Pass of Channel (하천 협소부에서 하상 이동성과 형태와의 상관성에 관한 하도수리학적 평가)

  • Choi, Ho-Kyun;Kim, Won-Il;Lee, Sam-Hee;Ahn, Won-Sik
    • Journal of Korea Water Resources Association
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    • v.42 no.2
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    • pp.141-148
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    • 2009
  • Each river in each country has peculiar channel characteristics at every section. Korea consists of mountains at the rate of 70%. Due to this, the sections that display unique channel form are scattered. One of the typical features is the narrow pass of channel section that presents in the process of the generation of alluvial channel and deformation channel. Around as this narrow pass of channel, it often comes to be regular flood disaster section. Regardless of this situation, investigations and plans that reflect channel characteristics at the narrow pass of channel have been wholly wanting until now. In accordance with this, we have investigated and analysed hydraulic significance and channel form of the narrow pass of channel in Seonsan in this study. The study has found real minute classification of sediment phenomenon at river bed of low flow channel on investigation section which is sand-bed river, but it was vaguely difficult to conclude that classification of sediment arises from explicit natural force. We were able to assume that the phenomenon comes from gentle bed slope, supply of river bed materials which is nearly uniformity. However, classification of sediment would come from collecting an aggregate rather than natural force. And we found that compound cross section conversion has been developing dramatically with channel form of movable bed section referring to movement which was active before at drainage district of the narrow pass of channel. With this, we could find the phenomenon that river width of low flow channel diminished largely. This kind of situation implies that it may cause compound section weighting, flood dimension decreasing, revetment at low flow channel or the local scour at bottom of levee when extraordinary flood occurs.