• 한국해안·해양공학회논문집
• /
• 제36권3호
• /
• pp.116-127
• /
• 2024

부잔교는 연안에 설치되는 대표적인 부유식 구조물로 선박의 접안 및 계류시설로 주로 활용되고 있으나, 파랑제어 및 파력발전 구조체와 같은 다양한 목적으로 활용하려는 시도가 계속되고 있다. 본 연구에서는 상하동요와 제한된 횡동요만을 허용하는 말뚝계류 부잔교를 대상으로 부유체의 유공구조 및 몰수판 부착에 따른 반사특성 및 동요특성을 실험적으로 검토하였다. 수리실험결과, 말뚝계류된 부잔교의 반사특성과 동요특성은 뷰유체의 유공구조 유무에 비해 몰수판의 설치 유무와 설치수심에 크게 의존함을 확인하였다. 특히, 몰수판의 설치는 단주기 파랑에서 반사계수를 증가시키고, 부유체의 상하동요 및 횡동요를 감소시키는 효과가 있었다.

• Steel and Composite Structures
• /
• 제25권4호
• /
• pp.505-521
• /
• 2017

The steel plate shear wall with beam-only connected infill plate (SSW-BO) is an innovative lateral load resisting system consisting of infill plates connected to surrounding beams and separated from the main columns. In this research, the effects of perforation diameter as well as slenderness ratios of infill plates on the hysteresis behavior of SSW-BO systems were studied experimentally. Experimental testing is performed on eight one-sixth scaled one-story SSW-BO specimens with two plate thicknesses and four different circular opening ratios at the center of the panels under fully reversed cyclic quasi-static loading in compliance with the SAC test protocol. Strength, stiffness, ductility and energy absorption were evaluated based on the hysteresis loops. It is found that the systems exhibited stable hysteretic behavior during testing until significant damage in the connection of infill plates to surrounding beams at large drifts. It is also seen that pinching occurred in the hysteresis loops, since the hinge type connections were used as boundaries at four corners of surrounding frames. The strength and initial stiffness degradation of the perforated specimens containing opening ratio of 0.36 compared to the solid one is in the range of 20% to 30% and 40% to 50%, respectively.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2013년도 추계학술대회
• /
• pp.149-150
• /
• 2013

최근 외해의 파랑을 막기 위한 방파시설로 유공방파제가 다수 설치되고 있다. 일반적으로 유공방파제는 전면에 유공격실을 설치하여 유공에서 난류를 발생을 유도하여 반사파를 저감하고, 최대 파력도 저감하는 목적을 지닌다. 유공벽은 폭풍파에 직접 노출되어 있어 쇄파 발생시 충격적인 파압이 작용될 수 있어 설계 시 유의하여야 한다. 본 논문에서는 이러한 문제가 없는 공진수로를 이용한 새로운 개념의 유공방파제를 제안하고, 중요 설계변수 변화에 대하여 제안한 시스템의 반사특성을 수치적으로 모의하였다. 수치해석은 유공판을 통과하면서 발생하는 난류에 의한 에너지 소모효과를 고려할 수 있는 선형 포텐셜 이론에 기초한 Galerkin 유한요소 모델을 이용하여 수행하였다. 유공판의 유공율에 따른 반사율 변화를 살펴보았다.

• 한국산림과학회지
• /
• 제84권4호
• /
• pp.432-436
• /
• 1995

본(本) 연구(硏究)는 국산(國産) 장미과(科)의 찔레꽃, 덩굴장미, 해당화, 공조팝나무 및 국수나무에 있어서 목부(木部) 방사조직(放射組織)내에 천공(穿孔)을 지니는 방사조직(放射組織) 구성세포(構成細胞)가 존재(存在)함을 처음으로 보고(報告)하는 것으로 이들 방사조직(放射組織) 세포(細胞)의 천공(穿孔)은 도관요소(導管要素)에 발달(發達)하는 천공(穿孔)과 동일(同一)하게 단일천공(單一穿孔)을 지니는 것으로 밝혀졌다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문초록집
• /
• pp.388.1-388
• /
• 2002

The sound absorption coefficients for multiple layer perforated plate systems containing several companments with airspaces and porous absorbing materials are estimated using the transfer matrix method developed in the previous paper. The absorption coefficients from transfer matrix method agree well with the values measured by the two-microphone impedance tube method fur various combinations of perforated Plates, airspaces or porous materials. (omitted)

• Journal of Mechanical Science and Technology
• /
• 제19권12호
• /
• pp.2224-2230
• /
• 2005

In this study, the validity of the Eshelby-type model for predicting the effective Young's modulus and in-plane Poisson's ratio of the 2-dimensional perforated plate has been investigated in terms of the porosity size and its arrangement. The predicted results by the Eshelby-type model are compared with those by finite element analysis. Whenever the ratio of the porosity size to the specimen size becomes smaller than 0.07, the effective elastic constants predicted by finite element analysis are convergent regardless of the arrangement of the porosities. Under these conditions, the effective Young's moduli of the perforated plate can be predicted within the accuracy of $5\%$ by the Eshelby-type model, which overestimates and underestimates the effective Poisson's ratios by $10\%\;and\;6\%$ for the plates with periodically and non-periodically arranged porosities, respectively.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제49권1호
• /
• pp.64-69
• /
• 2000

This paper investigates the equeeze film damping of a perforated planar micromechanical structure that oscillates in the normal direction to the substrate. Special focus has been places on the effect of holes and edges of the perforated planar microstructures on the squeeze film damping of oscillatory motions. Theoretical models and test structures of the squeeze film damping have been developed for the transversely oscillating perforated plates. A set of nine different test structures, having three different sized with three different numbers of perforations, has been fabricated and tested. The experimental Q-factors, measured from the fabricated test structures, are compared with the theoretical values, estimated from finite element analysis. It is found that the finite element analysis overestimates the Q-factors up to 150% of the experimental values. Major discrepancy comes from the inaccuracy of the zero pressure condition, placed by the finite element analysis along the perforated edges.

• Nuclear Engineering and Technology
• /
• 제37권6호
• /
• pp.557-564
• /
• 2005

Air-water countercurrent flow limitation at perforated plates with four holes was investigated in a vertical tank to see the effects of the plate thickness, the number of hole, and the diameter of the hole on the onset of CCFL. The thickness of plates was 1 cm and 4 cm, with a relatively large hole diameter of 5 cm. The collapsed water level formed on the perforated plate and its distribution in the upper plenum were measured. The gas flow rate in the multi-hole plate is relatively higher than one in the single tube because some of holes in the multi-hole plate provide a flow path fur liquid with less air-liquid resistance than in the single tube. The onset of CCFL occurred at nearly the same air flow rate regardless of the plate thickness. The negligible effect of the plate thickness on CCFL means that the flooding is initiated at the top of the plate rather than at its bottom. It turns out that $j_k$ and $K_k$ better fit the data than $H_k$ when hole diameter is greater than 2.86 cm. In our experimental ranges, the collapsed water levels at the onset of CCFL ranged from 7.5 cm to 10.5 cm. There was no three dimensional distribution of water level before and after the onset of CCFL.

• Steel and Composite Structures
• /
• 제29권6호
• /
• pp.771-783
• /
• 2018

In this paper, topology optimization (TO) is applied to find a new configuration for the perforated steel plate shear wall (PSPSW) based on the maximization of reaction forces as the objective function. An infill steel plate is introduced based on an experimental model for TO. The TO is conducted using the sensitivity analysis, the method of moving asymptotes and SIMP method. TO is done using a nonlinear analysis (geometry and material) considering the buckling. The final area of the optimized plate is equal to 50% of the infill plate. Three plate thicknesses and three length-to-height ratios are defined and their effects are investigated in the TO. It indicates the plate thickness has no significant impact on the optimization results. The nonlinear behavior of optimized plates under cyclic loading is studied and the strength, energy and fracture tendency of them are investigated. Also, four steel plates including infill plate, a plate with a central circle and two types of the multi-circle plate are introduced with equal plate volume for comparing with the results of the optimized plate.

• Journal of the Korean Wood Science and Technology
• /
• 제22권1호
• /
• pp.40-43
• /
• 1994

본(本) 논문(論文)은 버즘나무과(科)의 버즘나무 (Platanus orientalis L.)에 있어서 목부(木部) 방사조직(放射組織)내에 천공(穿孔)을 지니는 방사조직(放射組織) 세포(細胞)가 존재(存在)함을 처음으로 보고(報告)하는 것으로 이들 방사조직(放射組織) 세포(細胞)의 천공판(穿孔板)은 도관요소(導管要素) 상호간(相互間)에 발달(發達)하는 천공판(穿孔板)과 동일(同一)하게 단일천공판(單一穿孔板)과 계단상천공판(階段狀穿孔板)을 지니는 것으로 밝혀졌다.