Dynamic Wind Response of Twin Tall Buildings Linked by a Skybridge

Lim Juntack 한국풍공학회 2019 한국풍공학회지 Vol.23 No.3

스카이브릿지로 연결된 쌍둥이 초고층건물은 두 가지 종류의 연동성-스카이브릿지로 인해 두 건물의 거동 동기화를 유발하는 구조적 연동성과 작용하는 풍하중의 높은 상관성으로 인한 공기역학적 연동성-이 나타난다. 단일 건물에 널리 적용되는 전통적인 풍력실험 방법으로는 이런 연동성과 영향들을 완벽히 파악할 수 없는 실정이다. 그런 이유로 보다 발전된 동적 풍응답 해석법이 요구된다. 이 논문은 스카이브릿지로 연결된 쌍둥이 건물에서 발생하는 구조적 및 공기역학적인 연동성을 다룰 수 있는 듀얼 풍력실험 방법을 자세히 다루었다. 제안된 방법을 적용하여 건물의 풍가속도에 대한 구조적 및 공기역학적 연동성의 영향을 평가하였다. 건물의 풍응답 산정에 스펙트럼 적분법과 백색 소음 근사법을 적용하였다. 실험 및 결과로 볼 때 동적 풍응답에 상당한 영향이 있음을 확인할 수 있었다. 여러 개의 풍력 측정센서를 활용한 풍력실험 기술은 구조적으로 연결된 초고층건물에 대한 풍동실험에 유용하게 사용될 것으로 판단된다. Twin tall buildings linked a skybridge involve two types of coupling: the structural coupling, developed by a skybridge, synchronizing the motions of vibration of the two building and the aerodynamic coupling resulting from high cross-correlations of the components of wind loading. From the wind engineering viewpoint, an understanding of these couplings and their impacts on the wind-induced response of the buildings can not be fully accounted for when using the traditional high-frequency force balance (HFFB) approach tailored for single tall buildings, and thus this requires utilization of advanced dynamic wind response analysis. This paper addresses the dual- HFFB approach accounting for correlated wind loading and structurally coupled response of twin buildings with a skybridge. The proposed method is subsequently used to investigate the effects of aerodynamic and structural couplings on the rooftop accelerations of the buildings. Spectral integration and white-noise approximation approaches are employed in calculations of the building responses. The presented results show significant effects of both the aerodynamic and structural couplings. The multi-HFFB technique would be useful for wind tunnel study of structurally connected tall buildings.

지적구조 규명을 위한 키워드서지결합분석 기법에 관한 연구

이재윤,정은경 한국정보관리학회 2022 정보관리학회지 Vol.39 No.1

Intellectual structure analysis, which quantitatively identifies the structure, characteristics, and sub-domains of fields, has rapidly increased in recent years. Analysis techniques traditionally used to conduct intellectual structure analysis research include bibliographic coupling analysis, co-citation analysis, co-occurrence analysis, and author bibliographic coupling analysis. This study proposes a novel intellectual structure analysis method, Keyword Bibliographic Coupling Analysis (KBCA). The Keyword Bibliographic Coupling Analysis (KBCA) is a variation of the author bibliographic coupling analysis, which targets keywords instead of authors. It calculates the number of references shared by two keywords to the degree of coupling between the two keywords. A set of 1,366 articles in the field of ‘Open Data’ searched in the Web of Science were collected using the proposed KBCA technique. A total of 63 keywords that appeared more than 7 times, extracted from 1,366 article sets, were selected as core keywords in the open data field. The intellectual structure presented by the KBCA technique with 63 key keywords identified the main areas of open government and open science and 10 sub-areas. On the other hand, the intellectual structure network of co-occurrence word analysis was found to be insufficient in the overall structure and detailed domain structure. This result can be considered because the KBCA sufficiently measures the relationship between keywords using the degree of bibliographic coupling. 학문의 구조, 특성, 하위 분야 등을 계량적으로 규명하는 지적구조 분석 연구가 최근 급격히 증가하는 추세이다. 지적구조 분석 연구를 수행하기 위하여 전통적으로 사용되는 분석기법은 서지결합분석, 동시인용분석, 단어동시출현분석, 저자서지결합분석 등이다. 이 연구의 목적은 키워드서지결합분석(KBCA, Keyword Bibliographic Coupling Analysis)을 새로운 지적구조 분석 방식으로 제안하고자 한다. 키워드서지결합분석 기법은 저자서지결합분석의 변형으로 저자 대신에 키워드를 표지로 하여 키워드가 공유한 참고문헌의 수를 두 키워드의 주제적 결합 정도로 산정한다. 제안된 키워드서지결합분석 기법을 사용하여 Web of Science에서 검색된 ‘Open Data’ 분야의 1,366건의 논문집합을 대상으로 분석하였다. 1,366건의 논문집합에서 추출된 7회 이상 출현한 63종의 키워드를 오픈데이터 분야의 핵심 키워드로 선정하였다. 63종의 핵심 키워드를 대상으로 키워드서지결합분석 기법으로 제시된 지적구조는 열린정부와 오픈사이언스라는 주된 영역과 10개의 소주제로 규명되었다. 이에 반해 단어동시출현분석의 지적구조 네트워크는 전체 구성과 세부 영역 구조 규명에 있어 미진한 것으로 나타났다. 이러한 결과는 키워드서지결합분석이 키워드 간의 서지결합도를 사용하여 키워드 간의 관계를 풍부하게 측정하기 때문이라고 볼 수 있다.

Coupling material characteristics with water–cement ratio for elastic wave based monitoring of underground structure

Lee, Jong-Won,Oh, Tae-Min,Kim, Hyunwoo,Kim, Min-Koan Elsevier 2019 Tunnelling and underground space technology Vol.84 No.-

<P><B>Abstract</B></P> <P>Elastic wave based technology (e.g., acoustic emission or micro seismic sensors) has been widely used to monitor the stability of underground structures or rock failure. To achieve successful measurement, it is important to select an appropriate coupling material for the installation of sensors that are embedded in holes bored into the wall of a structure. The characteristics of the coupling material are related to its wave propagation ability (i.e., wave velocity and damping ratio), setting ability in the borehole (i.e., bleeding), and its workability (i.e., viscosity) in relation to being able to fill the holes tightly with the sensors. In this study, micro cement, Portland cement, and gypsum were the materials considered to couple with sensors in the borehole. Laboratory tests were performed to evaluate the characteristics of the coupling material according to the water-cement ratio (w/c, range 0.5–2.0). The test results show that the propagation ability and setting ability tend to decrease with increasing w/c ratio; on the other hand, workability benefits from an increasing w/c ratio. In addition, the characteristics of the coupling materials were analyzed to suggest a material with an optimized w/c ratio appropriate for a target test-bed site. The most suitable coupling recipe was found to be micro cement with a w/c ratio of 1.0. This study provides information about coupling material characteristics that should be useful for determining a suitable coupling recipe for field applications.</P>

Feedback control strategies for active control of noise inside a 3-D vibro-acoustic cavity

Ashok K. Bagha,Subodh V. Modak 국제구조공학회 2017 Smart Structures and Systems, An International Jou Vol.20 No.3

This paper presents and compares three feedback control strategies for active control of noise inside a 3-D vibro-acoustic cavity. These are a) control strategy based on direct output feedback (DOFB) b) control strategy based on linear quadratic regulator (LQR) to reduce structural vibrations and c) LQR control strategy with a weighting scheme based on structural-acoustic coupling coefficients. The first two strategies are indirect control strategies in which noise reduction is achieved through active vibration control (AVC), termed as AVC-DOFB and AVC-LQR respectively. The third direct strategy is based on active structural-acoustic control (ASAC). This strategy is an LQR based optimal control strategy in which the coupling between the various structural and the acoustic modes is used to design the controller. The strategy is termed as ASAC-LQR. A numerical model of a 3-D rectangular box cavity with a flexible plate (glued with piezoelectric patches) and with other five surfaces treated rigid is developed using finite element (FE) method. A single pair of collocated piezoelectric patches is used for sensing the vibrations and applying control forces on the structure. A comparison of frequency response function (FRF) of structural nodal acceleration, acoustic nodal pressure, and piezoelectric actuation voltage is carried out. It is found that the AVC-DOFB control strategy gives equal importance to all the modes. The AVC-LQR control strategy tries to consume the control effort to damp all the structural modes. It is seen that the ASAC-LQR control strategy utilizes the control effort more intelligently by adding higher damping to those structural modes that matter more for reducing the interior noise.

LRB를 이용한 병렬전단벽 구조물의 지진응답제어

박용구,김현수,고현,김민균,이동근 한국지진공학회 2010 한국지진공학회논문집 Vol.14 No.6

대부분의 전단벽 구조물은 통로의 목적으로 개구부를 필요로 하게 되고 전단벽들 사이가 슬래브나 연결보로 연결된 병렬 전단벽의 형태를 띠게 된다. 이러한 구조물에 지진하중이 작용할 때 연결보에 과도한 전단력이 작용하여 연결보가 취성적으로 파괴되거나 전단벽이 먼저 항복하는 문제점이 발생할 수 있다. 이를 방지하기 위하여 연결보에 감쇠장치를 설치하게 되면 구조물의 진동제어효과와 더불어 연결보의 응력집중 및 취성적 파괴를 막을 수 있어서 내진성능 향상을 기대할 수 있다. 본 논문에서는 병렬전단벽 연결보 중앙부에 LRB (Lead Rubber Bearing)가 설치된 구조물의 지진응답제어효과 및 응력의 분포를 평가하여 구조적 효율성을 확인하고자 한다. 이를 위하여 병렬전단벽의 거동을 비교적 정확하게 모사할 수 있는 모형화 방법을 제안하였고, 제안된 모형화 방법을 통하여 지진하중을 받는 예제 병렬구조물에 대한 시간이력해석을 수행한 후 지진응답제어성능을 검토하였다. Most of shear wall structures require openings in shear walls and thus shear walls are linked by floor slabs or coupling beams resulting in the coupled shear wall structures. When these structures are subjected to seismic excitations, excessive shear forces are induced in coupling beams. Accordingly, brittle failure of coupling beams may occur or shear walls may yield first. To avoid this problem, damping devices can be installed in coupling beams. It can increase the vibration control effect and improve the seismic resistance performance of the coupled shear wall structure by avoiding stress concentration and the brittle failure of coupling beams. Based on this background research, an LRB (lead rubber bearing) was introduced in the middle of the coupling beam in this study and the authors investigated the seismic response control effect and stress distribution of the proposed system. To this end, a modeling technique that can effectively predict the structural behavior of coupled shear wall structures has been proposed. With this proposed technique, time history analyses of the example coupled shear wall structure subjected to seismic excitation were performed and the vibration control effects of the seismic responses were investigated.

입구와 유연한 구조물로 구성된 경계를 가지는 구조-음향 연성계의 수학적 표현

서희선(Seo, Hee-Seon),김양한(Kim, Yang-Hann) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.5

This paper explains a general coupling system in terms of the system parameters. impedance of a cavity or mobility of a structure. To easily access the mechanism of the structural-acoustic coupled system, a simple expression is derived. A general coupled equation is also derived of a general coupled problem constituted a flexible structure and an opening boundary in terms of vector and matrix notation, and is analyzed the coupling phenomena using the understanding acquired simple coupled system. The paper shows that the general coupled equation is expanded version of the simple coupled equation by some limiting checks. The paper also shows that the degree of coupling is proportioned to a stiffness of the acoustic system and a modal coupling coefficient, but is in inverse proportion to a mass of the structural system and the difference of the excitation frequency and resonant frequency of the acoustic or structural system.

소성거동을 고려한 병렬 RC 구조벽체시스템의 설계

유승윤,엄태성,강수민 한국전산구조공학회 2017 한국전산구조공학회논문집 Vol.30 No.4

본 연구에서는 다양한 변수를 갖는 병렬 RC 구조벽체시스템에 대한 성능기반설계의 타당성과 이에 따른 모멘트 재분배 개념의 적용성을 분석하기 위해 횡력을 지지하는 병렬 RC 구조벽체시스템에 대한 비선형해석을 수행하였다. 설계변수(철근 비, 콘크리트변형률, 벽체높이)가 병렬 RC 구조벽체시스템의 거동에 미치는 영향을 분석하였으며 이를 기반으로 병렬 RC 구조벽체시스템의 성능기반 설계를 위한 고려사항을 제안하였다. 비선형해석 결과, 병렬 RC 구조벽체시스템 성능기반 설계 와 모멘트 재분배 개념의 적용을 위해서는 연결보의 항복여부에 대한 고려가 필요한 것으로 나타났다. 높은 벽체의 경우, 연 결보가 항복하지 않고 탄성 상태로 거동할 수 있기 때문에 고층 병렬 RC 구조벽체시스템에 대해 성능기반 설계 및 모멘트 재분배 개념을 적용하기 위해서는 벽체에 높은 수준의 소성변형능력을 필요로 하며, 이를 위해 벽체 압축단부에 횡보강을 필수적으로 실시해야 한다. Reinforced concrete(RC) structural walls are major lateral load-resisting structural member in building structures. Generally these RC structural walls are coupled with each other by the coupling beams and slabs, and therefore they behave as RC coupled structural wall system. In the design of these coupled structural wall systems, member forces are calculated using elastic structural analysis. These elastic analysis methodologies for the design of coupled structural wall system was not reasonable because it can not consider their ultimate behavior and assure economic feasibility. Performance based design and moment redistribution method to solve these problems is regarded as a reasonable alternative design method for RC coupled structural wall system. However, it is not verified under various design parameters. In this study, nonlinear analysis of RC coupled structural wall system was performed according to various design parameters such as reinforcement ratio, ultimate concrete strain and wall height. Based on analysis results, design considerations for coupled RC structural wall system was proposed.

Dynamic Wind Response of Twin Tall Buildings Linked by a Skybridge

임준택 한국풍공학회 2019 한국풍공학회지 Vol.23 No.3

Twin tall buildings linked a skybridge involve two types of coupling: the structural coupling, developed by a skybridge, synchronizing the motions of vibration of the two building and the aerodynamic coupling resulting from high cross-correlations of the components of wind loading. From the wind engineering viewpoint, an understanding of these couplings and their impacts on the wind-induced response of the buildings can not be fully accounted for when using the traditional high-frequency force balance (HFFB) approach tailored for single tall buildings, and thus this requires utilization of advanced dynamic wind response analysis. This paper addresses the dual-HFFB approach accounting for correlated wind loading and structurally coupled response of twin buildings with a skybridge. The proposed method is subsequently used to investigate the effects of aerodynamic and structural couplings on the rooftop accelerations of the buildings. Spectral integration and white-noise approximation approaches are employed in calculations of the building responses. The presented results show significant effects of both the aerodynamic and structural couplings. The multi-HFFB technique would be useful for wind tunnel study of structurally connected tall buildings.

Structural Features of 2 Adrenergic Receptor: Crystal Structures and Beyond

방인진,최희정 한국분자세포생물학회 2015 Molecules and cells Vol.38 No.2

The beta2-adrenergic receptor (β2AR) belongs to the G protein coupled receptor (GPCR) family, which is the largest family of cell surface receptors in humans. Extra attention has been focused on the human GPCRs because they have been studied as important protein targets for pharmaceutical drug development. In fact, approximately 40% of marketed drugs directly work on GPCRs. GPCRs respond to various extracellular stimuli, such as sensory signals, neurotransmitters, chemokines, and hormones, to induce structural changes at the cytoplasmic surface, activating downstream signaling pathways, primarily through interactions with heterotrimeric G proteins or through Gprotein independent pathways, such as arrestin. Most GPCRs, except for rhodhopsin, which contains covalently linked 11 cis-retinal, bind to diffusible ligands, having various conformational states between inactive and active structures. The first human GPCR structure was determined using an inverse agonist bound β2AR in 2007 and since then, more than 20 distinct GPCR structures have been solved. However, most GPCR structures were solved as inactive forms, and an agonist bound fully active structure is still hard to obtain. In a structural point of view, β2AR is relatively well studied since its fully active structure as a complex with G protein as well as several inactive structures are available. The structural comparison of inactive and active states gives an important clue in understanding the activation mechanism of β2AR. In this review, structural features of inactive and active states of β2AR, the interaction of β2AR with heterotrimeric G protein, and the comparison with β1AR will be discussed.

Structural, vibrational, and enhanced magneto-electric coupling in Ho-substituted BiFeO₃

Muneeswaran, Muniyandi,Lee, Seung Hoon,Kim, Dong Hun,Jung, Beon Sung,Chang, Seo Hyoung,Jang, Jae-Won,Choi, Byung Chun,Jeong, Jung Hyun,Giridharan, N.V.,Venkateswaran, C. Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.750 No.-

<P><B>Abstract</B></P> <P>The effect of Holmium (Ho) substitution in BiFeO<SUB>3</SUB> [Bi<SUB>1-x</SUB>Ho<SUB>x</SUB>FeO<SUB>3</SUB> (x = 0.00, 0.05, 0.10, 0.15, 0.18, and 0.20)] ceramics is reported. The X-ray diffraction study shows composition-driven rhombohedral-to-orthorhombic (<I>R</I>3<I>c</I> to <I>Pnma</I>) phase transition for Bi<SUB>1-x</SUB>Ho<SUB>x</SUB>FeO<SUB>3</SUB> (x = 0.15, 0.18, and 0.20) which is confirmed by Reitveld refinement. Raman spectra of Bi<SUB>1-x</SUB>Ho<SUB>x</SUB>FeO<SUB>3</SUB> (x = 0.00, 0.05, and 0.10) belong to the rhombohedral (<I>R</I>3<I>c</I>) structure. Further increasing the Ho<SUP>3+</SUP> concentration in a BiFeO<SUB>3</SUB> (BFO) system revealed that Raman modes of Bi<SUB>1-x</SUB>Ho<SUB>x</SUB>FeO<SUB>3</SUB> (x = 0.15, 0.18 and 0.20) were assigned to an orthorhombic (<I>pnma</I>) structure, which is confirmed by the Rietveld analysis of X-ray diffraction data and TEM analysis. Ferroelectric studies show that the remnant polarization (P<SUB>r</SUB>) gradually decreases for Bi<SUB>1-x</SUB>Ho<SUB>x</SUB>FeO<SUB>3</SUB> (x = 0.15, 0.18, and 0.20), confirming the transformation from polar to non-polar systems. Magnetic measurement shows ferromagnetic behavior observed for Bi<SUB>1-x</SUB>Ho<SUB>x</SUB>FeO<SUB>3</SUB> (x = 0.10 and 0.20) samples. Further, the magneto-electric coupling is measured in terms of magneto-capacitance of Ho<SUP>3+</SUP>-substituted BiFeO<SUB>3</SUB> samples.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ho<SUP>3+</SUP> substituted BFO ceramics were synthesized by a solid-state reaction. </LI> <LI> Structural transformation from rhombohedral (<I>R</I>3<I>c</I>) to orthorhombic (<I>Pbnm</I>). </LI> <LI> Higher Ho<SUP>3+</SUP> substituted BFO is assigned orthorhombic (<I>Pbnm</I>) by Raman studies. </LI> <LI> Enhanced magneto-electric coupling observed in Ho<SUP>3+</SUP> substituted BFO samples. </LI> </UL> </P>