The precast concrete (PC) method allows for simple assembly and disassembly of structures; however, ensuring airtight connections is crucial to prevent energy loss and maintain optimal building performance. This study focuses on the analytical investigation of the shear capacity of precast ultra-high-performance concrete (UHPC) ribs combined with standard concrete PC cladding walls. Five specimens were tested under static loading conditions to evaluate their structural performance and the thermal behavior of the UHPC rib shear keys. Test results indicated that the specimens exhibited remarkable structural performance, with shear capacity approximately three times greater than that of standard concrete. Numerical models were subsequently developed to predict the shear capacity of the shear keys under various loading conditions. A comparison between the experimental results and finite element (FE) models showed a maximum strength difference of less than 10% and a rib displacement error of up to 1.76 mm. These findings demonstrated the efficiency of the FE model for the simulation of the behavior of structures.

In this study, We designated the injection molded plug housing for charging electric vehicles as a research subject. And we analyzed the effect of Rib design on the quality of injection molded products. First, we used the Taguchi method to derive optimal conditions for rib design. The factors were set as the Thickness of the rib, the Height of the rib, and the Radius of the rib. Each factor consisted of 5 levels and generated conditions for a total of 125. We performed an injection molding analysis and confirmed significant factors affecting the deformation of injection molded products through ANOVA. Based on this, the 25th design detail was selected as the optimal condition. In addition, We compared the results of the molding analysis with the molded products that did not design ribs. We confirmed that the molded product designed with ribs under optimal design detail improved the deformation amount by 22.22% and the residual stress by 8.35%, compared to the molded product not designed with ribs.

본 연구는 재래 철근콘크리트공법의 거푸집 및 철근보강재를 FRP 판으로 대체한 개념이다. FRP판에 리브를 갖게 하여 FRP 판과 콘크리트 합성을 개선하고 거푸집의 강성증가를 유도하여 영구거푸집 및 철근보강재로 활용하는 방안이다. 본 연구는 전단경간비가 짧고 리브가 있는 FRP 판과 콘크리트 합성보의 휨/전단 파괴거동과 균열형태를 비교 분석하였다. 콘크리트의 경우 CDP 모델을 사용하였고, 외연적 비선형 유한요소해석 결과와 기존 실험결과를 정점 하중 및 균열형태에 대해 비교 분석하였다. 유효균열방향 개념을 사용하여 콘크리트 균열패턴을 시각적으로 표현하였다. 인장 등가소성변형률이 0 보다 큰 곳에서 균열이 시작된다고 가정하고, 균열평면에 수직인 벡터의 방향은 최대 주소성변형률의 방향과 평행한 것으로 가정하였다. 이 방향을 콘 크리트의 균열으로 생각하여 실험에서 확보한 균열형태와 비교 분석하였다. ABAQUS/Explicit 의 CDP 모델은 FRP 합성구조체의 비선형 거동 및 균열형태 모사가 가능한 것으로 판단된다. 초기강성의 불일치는 리브가 있는 FRP 판과 콘크리트 사이의 미세균열 및 접착력 등의 문제로 인해 발생한 것으로 사료되며 1차 정점 하중 및 균열형태를 적절히 추적할 수 있으므로 앞으로 다양 한 FRP 합성구조시스템의 거동 및 균열해석에 이용 가능할 것으로 판단되나 보다 다양한 파괴 매카니즘에 대한 지속적인 연구가 필요하다고 사료된다.

When the product is taken out after the injection process, the surface of the product and the mold are attached and to separate them, it is necessary to consider the frictional force between the mold surface and the product surface. Therefore, to reduce the frictional force, a subtraction gradient for the rib shape is generally applied, and a lapping process is performed to improve the surface roughness of the rib shape surface of the processed mold. Therefore, research is needed to improve the surface roughness when processing the rib. In this study, slotting processing was applied to improve surface roughness when processing ribs. Slotting processing is a processing method that removes material through the feed motion of the tool, and processing is possible regardless of the aspect ratio of the processing shape. A slotting tool was developed for rib machining and a comparative experiment with electric discharge machining was performed. Also after processing, the surface roughness and processing time were compared and analyzed, and the improved surface roughness and fast processing time characteristics of the slotting processing compared to electric discharge processing were confirmed.

Using closed-section ribs as longitudinal stiffeners have been proven to be an effective system for axially compressed members, however, studies on the application of these on laminated composite shell are insufficient. Thus, this study aims to evaluate the buckling behavior of the laminated composite shell when closed-section ribs were applied as longitudinal stiffeners. The effect of the rotational stiffness of the closed-section ribs on the buckling modes and strengths will be determined in this paper. The three-dimensional finite element modeling were set up using ABAQUS and a series of eigenvalue analysis were conducted, applying eight layers of the layup [(0°)4]s, [(45°/-45°)2]s and [(0°/90°)2]s on the orthotropic plates. Through the parametric studies, the increasing effect on the elastic buckling strengths due to the rotational stiffness are numerically verified, and the buckling strength of a longitudinally stiffened shell with a laminated composite material were compared with that of the isotropic material.

The ribs of the injection molded article are a necessary shape in order to maintain the rigidity without increasing the material cost. The ribs on the outside of the molded article in the form of a housing are located on the side of the cavity inside in the mold. This paper proposes slotting by machining side-ribs. The slotting was performed through CNC control along the edge profile of the rib width. The machining time and the roughness of the machined surface were compared to verify the machining efficiency and the practicality of the machining method as a side-rib machining method.

Recent studies have revealed that plates stiffened by closed-section ribs can be designed to have greater strength. Thus, this study is about the increasing effect on local plate buckling strength of isotropic plates when longitudinally stiffened with closed-section ribs, which is mainly due to the rotational restraint of the closed-section ribs. The effects on buckling strengths of the stiffened plates are examined by numerical analyses. Three-dimensional finite element models were obtained using a general structural analysis program ABAQUS and a series of eigenvalue analyses were conducted. Through this study, the increasing effect on the local buckling strength due to the rotational stiffness is numerically verified. From the parametric studies, there is an obvious tendency that the local buckling strength of the stiffened plate would converge to the buckling strength of plate with fixed boundary condition. The findings of this study would contribute in improving the optimum design of longitudinally stiffened isotropic plates.

This study is about the basic design technology to radically increase the structural stability of structural shell or tube, which are utilized in a variety of large structures like aircrafts, plant, bridges and buildings. Recent studies have revealed that the plates stiffened by closed-sections ribs can be designed to have greater strength as well as the reduction of used number of stiffeners. Then, the analytical models were selected based on the huge steel tube design and the finite element modeling has been conducted using the ABAQUS. Through this study, the elastic buckling strengths are compared with the flat plate buckling stress and the improved effect in the local buckling strength due to the closed-section ribs are numerically verified.

Molding trouble in injection-molded parts is caused by change of complexed molding product and molding process condition, etc. Warpage, which is one of the molding trouble, acts as possible factor which results in defect in assembly. In this study, a mold was designed to produce specimens with rib parallel to flow direction, specimens with rib perpendicular to flow direction and specimens without rib. This work researched change of warpage according to injection molding condition such as packing pressure, packing time, resin temperature in crystalline polymers(PP). Flat shape with ribs showed higher warpage than flat shape without ribs. The Specimens with ribs that are located perpendicular to the flow direction.

Most of the plastics products have been manufactured by injection molding. Molding trouble in injection-molded parts is caused by changing a molding product and molding process condition, etc. In this study, warpage in the injection molded part have been studied. specimens are rectangular flat shape with and without ribs. Non-crystalline resins (PC) and crystalline resins (PA66) were used for material and 30% glass fiber reinforced-resins(PC, PA66). Flat shape ribs showed higher warpage than flat shape without rib by 10 to 41%. the specimens with ribs that are located parallel to flow direction has higher warpage than the specimens with rib that are located perpendicular to flow direction by 11 to 50%. crystalline resins have higher warpage than non-crystalline resins by 22 to 78%.

Knit fabrics are created on diverse machines with diverse knit loops and conditions to make different patterns and fabric types1). Dimensional modifications of knit fabrics can also be achieved by numerous methods such as different knit-loop structures, different types of yarns, or different finishing processes including heat setting, steaming, chemical treatment et cetera. This research develops and explores sophisticated three-dimensional knit fabrics by combining the several different knit stitches including rib and purl. This study focuses on 3D knit models created on modern electronic weft (flat V-bed) knitting machines which have capability of individual needle selection. Several samples of the 3D knitted fabrics are also examined in this research. This research furthermore suggests new types of knitted fashion garment made by using the interesting physical effects.

최근 장대화 되어가는 강교량의 건설 기술발전에 따라, 자중이 가벼운 강바닥판 형식의 교량 사용이 증가되고 있다. 그러나 강바닥판 교량은 피로에 매우 취약한 구조형식이며, 특히 종리브와 횡리브가 교차되는 상세부에서의 피로균열은 강바닥판 교량이 가지고 있는 가장 큰 문제점 중 하나이다. 이러한 피로균열의 발생원인은 횡리브의 면외거동에 의한 2차 응력으로부터 유발된다. 본 연구에서는 강바닥판 교량의 피로균열을 억제하고, 종리브-횡리브 교차연결부의 상세개선을 위해 3차원 실물모형체의 피로실험과 범용구조해석 프로그램인 LUSAS를 이용한 세부변수 해석을 병행하여 최적의 상세를 제시하기 위한 연구를 수행하였다. 연구 결과, 국내 표준단면 형상에 곡선형 벌크헤드 플레이트를 부착한 상세가 가장 유리한 것으로 나타났으며, 세부 변수해석에 의한 개선 단면 적용시 발생되는 응력값이 최대의 경우 약 50%이상까지 감소하는 것으로 나타났다. 응력의 감소와 함께 횡리브의 간격 증대(G=400)에 따른 4%의 강재량과 34%의 용접길이 감소로 제작원가 절감 및 피로에 유리한 강바닥판교의 제작이 가능하게 되었다.

이 연구에서는 전단연결재의 종류를 변수로 더블리브유닛 깊은 데크플레이트 슬래브의 휨 실험을 수행하였으며, 실험결과를 기반으로 비선형유한요소해석을 통하여 춤이 깊은 데크플레이트와 콘크리트 사이의 합성도를 평가하였다. 그 결과, 전단 연결재가 설치되어 있는 경우 휨 강성 및 강도가 크게 향상되는 것으로 나타났다.

The purpose of this study is to investigate the causes of corrosion of steel plate deck longitudinal U-ribs and to investigate the reinforcement method. It was confirmed that the corrosion of the longitudinal U-ribs occurred due to penetration water of the bolt hole of the shear key used in construction. The longitudinal U-ribs which were corroded were stiffened by attaching reinforcing plates, and finishing treatment was performed to prevent the surface water from flowing into the inside.

In this study, long term monitoring of tensile force of pre-tensioned prestressing strand embedded in UHPC ribbed deck by means of FBG sensor encapsulated into 7-wire prestressing strand. Based on the monitoring result for two years, it was confirmed that the technique proposed in this study offers efficient and robust way of monitoring the internal prestress of pre-tensioned PSC structures.

In this paper, the buckling analysis was performed to compare the buckling mode and the buckling load for siffened plates having ㄷ, Reverse T, corrugated wave, ㄹ, honeycomb and ㅁ types of ribs. In the case of the rib space S=300mm, various types of buckling modes were appeared according to the rib types. In the case of the rib space S=450 and 600mm, the buckling loads of ㄹ, ㅁ and honeycomb were bigger than that of ㄷ and ㅁ type was the biggest.