Study of the distribution and species composition of the megabenthos in the South Sea of Korea

우리나라 남해, 제주도 및 이어도 해역은 고온, 고염분의 제주난류, 중국의 양쯔강으로부터 흘러나오는 저염수와 황해 저층냉수대의 영향을 받는다. 또한 계절에 따른 다양한 수괴 형성으로 인해 다양한 환경변화가 나타나는 것으로 알려져 있다. 이러한 다양한 환경 변화가 나타나는 제주도 주변 해역은 높은 생물다양성을 나타내며, 따라서 본 연구 지역의 생물다양성도 높을것으로 생각되어진다. 그러나, 본 연구지역의 저서동물에 관한 연구는 대형저서동물의 종 조성과 군집에 한정되었으며, 초대형저서동물에 관한 연구는 매우 제한적이다. 따라서 본 연구에서는 우리나라 남해 및 인근 해역의 초대형저서동물의 종 조성 및 분포를 분석하였다. 초대형저서동물은 2015년 6월, 11월 2016년 4월 17개 정점에서 Beam trawl (width:1.0m)을 10분 동안 예인하여 채집되었다. 초대형저서동물은 총 301종이 출현하였으며, 평균서식밀도는 28.7 ind/100 m2, 평균 생체량은 81.1 g/100 m2으로 나타났다. 주요 우점종은(> 1 % of the total density) 지붕거미불가사리(Stegophiura sterea), 버선조개(Mactrinula dolabrata), 호두조개(Acila divaricata), 고둥끈말미잘(Hormathia andersoni)순으로 나타났다. 초대형저서동물의 군집구조는 깊이에 따라 2015년 6월 3개의 그룹, 2015년 11월 두 개의 그룹으로 나뉘었으며, 2016년 4월 초대형저서동물의 군집구조는 퇴적물 조성에 따라 두 개의 그룹으로 나뉘었다. 총 종수, 종다양도, 평균 생체량은 남해에 위치한 정점 C3에서 각각 116종, 3.7, 1173 g/100 m2으로 높게 나타났으며, 총 종수, 종다양도, 평균서식밀도는 제주도 남쪽에 위치한 정점 H12에서 각각 5종, 1.3, 1.4 g/100 m2으로 낮게 나타났다. 생물다양성의 차이는 환경요인 중 수심, 자갈 함유량, 분급도에 영향을 받는것으로 나타났다. 이러한 결과는 남해 해역의 해양환경의 변동이 초대형저서동물의 종 조성과 분포 및 다양도에 영향을 주는 것으로 보인다.|The South Sea of Korea is affected by three systems of currents: the high-temperature, high-salinity Jeju Warm Current; the low-salinity Yangtze River discharge flow from China; and the cold-water bottom currents of the Yellow Sea. In addition, seasonal flow differences from various water flows drive environmental variability in these regions. As a result, biodiversity in this study area is assumed to be very high. However, there is no information on the diversity and distribution of the megabenthos. Therefore, in this study, we analyzed the diversity and distribution of the megabenthos in the South Sea based on environmental factors. Sampling of megabenthos were collected using a Beam trawl for 10 minutes towed at 17 stations in June 2015, November 2015, April 2016. The total number of species, density (ind/100 m2), and biomass (g/100 m2) of megabenthos were 301 species/9900 m2, 28.7 ind/100 m2, and 81.1 g/100 m2, respectively. The dominant species (> 1% of the total density) were Stegophiura sterea (10.4%), and two subtropical species Mactrinula dolabrata (9.0%), and Acila divaricate (8.3%) (bivalve mollusks). Megabenthic community structures in June and November 2015 were divided into three groups and two groups, respectively, which were affected by water depth. However, in April 2016, megabenthic community was divided into two groups according to sediment grain sizw and sorting value (σ). The total numbers of species, diversity and biomass were highest in st. C3 (116 species, 3.7 and 1173 g/100 m2 respectively) and lowest in st. H12 (5 species, 1.3 and 1.4 g/100 m2 respectively). According to the environmental factor analysis, the differences in megabenthos community were found to be related to depth, gravel contents, and sorting value (σ). This study suggests that variations in sediment conditions and depth in the South Sea of Korea are important factors controlling at the megabenthos species composition and diversity.1. Introduction 1 1.1 Megabenthos 1 1.2 Information of study area 2 1.3 Aims of this study 3 2. Materials and Methods 4 2.1 Collecting samples 4 2.2 Environment analysis 6 2.3 Making images 7 2.4 Data analysis 8 3. Result 9 3.1 Environmental conditions 9 3.2 Diversity of megabenthos 11 3.3 Distribution and species composition of megabenthos 35 3.3.1 Species composition 35 3.3.2 Dominant species 38 3.3.3 Community structure 41 4. Discussion 55 4.1 Environmental conditions 55 4.2 Ecological characteristics and biogeography on the megabenthos species in this study area 55 4.3 Impact of environmental conditions on the distribution and species composition of the megabenthos 56 감사의 글 60 References 61Maste

휨지배 구조벽체의 연성설계

Thesis (doctoral)--서울대학교 대학원 :건축학과,2004.Docto

A Case Study on the Performance Factors of Culture and Arts Organizations : focusing on Public Symphony Orchestras

학위논문(석사) --서울대학교 행정대학원 :행정학과(행정학전공),2009.2.Maste

긴 장방형 콘크리트 벽체의 극한 거동에 관한 연구

학위논문(석사)--서울대학교 대학원 :건축학과,2000.Maste

Moment-Curvature Relationoship of Structural Walls with Confined Boundary Element

For performance-based design using nonlinear static analysis. it is required to predict the inelastic behavior of structural members accurately. In the present study, a nonlinear numerical analysis was performed to develop the method describing the moment-curvature relationship of structural wall with boundary confinement. Through the numerical analysis. variations of behavioral characteristics and failure mechanism with the arrangement of vertical reinforcement and the length of boundary confinement were studied, According to the analysis. the maximum moment-carrying capacity of structural walls with adequately confined boundary elements is developed at the moment the unconfined concrete reaches the ultimate compressive strain, Walls with flexural re-bars concentrated on the boundaries fails in a brittle manner. As vertical re bars in the web increases. the brittle failure is prevented and a ductile failure occurs, Based on the findings. moment-curvature curves for walls with a variety of re-bar arrangement were developed, According to the proposed relationships. deformability of the structural walls wth boundary confinement increases as the compressive strength of the confined concrete increases compared to the applied compressive force.본 연구는 두뇌한국212 핵심분야사업 및 한국과학재단 특정기초연구사업(과제번호:1999-1-310-002-3)의 재정적 지원에 의하여 이루어졌

Design of Boundary Confinement of Structural Walls

For a performance-based design of structural walls, it is necessary to develop a rational design method for determining the length and detail of boundary confinement so as to satisfy the given ductility demand. In the present study, the curvature capacity of a structural wall with boundary confinement was estimated considering the effects of various design parameters. The curvature demand of the plastic hinge corresponding to the given design displacement was also determined. By equalizing the curvature capacity to the demand, a design method for determining the length of boundary confinement, was developed. According to the design method, the length of boundary confinement increases as axial compressive load and design displacement increase, and as concrete strength, wall thickness, amount of lateral reinforcement and aspect ratio decrease. A study was performed on details for effective lateral confinement of walls with rectangular cross- section. Based on the findings, design guidelines on spacings of ties and cross-ties were proposed.본 연구는 한국과학재단 특정기초연구사업 (과제번호 : 1999-1-310-002-3)의 재정적 지원에 의하여 이루어졌음을 밝히며, 지원에 감사드립니다

Ductility Confinement of RC Rectangular Shear Wall

In designing the boundary confinement of shear walls, the current design provisions and recommendations are empirical and prescriptive; they specify a certain confinement length and details, regardless of the actual requirement of ductility. Therefore, they are inappropriate to the performance based-design. The purpose of the present study is to develop a ductility design method that is applicable to the performance based-design of shear wall. For the purpose, experimental studies were performed to investigate variations in the ductility of shear walls with the length of the boundary confinement. Five specimens modeling the compressive zone of cross sections with different confinement area were tested against eccentric vertical load. Through the experimental studies, strength, ductility, and failure mode of the compression zone were investigated. In addition, nonlinear numerical analyses for the overall cross-sections of shear wall were performed to investigate variations of the stress and strain profiles with the length of compression zone. On the basis of the experimental and numerical studies, a ductility design method for shear wall was developed. By using the proposed design method, for a given ductility demand, the area of lateral confinement and corresponding reinforcement ratio can be precisely determined so that the ductile behavior and economical design are assured.본 연구는 두뇌한국21 핵심분야사업 및 한국과학재단 특정기초연구사업 (과제번호:1999-1-310-002-3)의 재정적 지원에 의하여 이루어졌음을 밝히며, 지원에 감사드립니다

Behavioral Characteristics and Energy Dissipation Capacity of Short Coupling Beams with Various Reinforcement Layouts

The cyclic behavior and energy dissipation mechanism of short coupling beams with various reinforcement layouts were studied. For numerical analysis of coupling beams, nonlinear truss model was used. The results of numerical analysis showed that the coupling beams with conventional reinforcement layout showed pinched cyclic behavior without significant energy dissipation, whereas the coupling beams with diagonal reinforcement exhibited stable cyclic behavior without pinching. The energy dissipation of the coupling beams was developed mainly by diagonal reinforcing bars developing large plastic strains rather than concrete which is a brittle material Based on this result, simplified equations for evaluating the energy dissipation of coupling beams were developed. For verification, the predicted energy dissipation was compared with the test results. The results showed that the simplified equations can predict the energy dissipation of short coupling beams with shear span-to-depth ratio less than 1.25 with reasonable precision, addressing various design parameters such as reinforcement layout, shear span-to-depth ratio, and the magnitude of inelastic displacement. The proposed energy equations can be easily applied to performance-based seismic evaluation and design of reinforced concrete structures and members. ; 본 연구에서는 다양한 배근상세를 갖는 짧은 연결보(short coupling beam)의 주기거동특성과 에너지소산 메커니즘을 연구하였다. 주기하중을 받는 연결보의 수치해석을 위하여 비선형트러스모델 (nonlinear truss model)을 사용하였다. 수치해석 결과, 일반적인 수직·수평배근상세를 갖는 연결보는 핀칭이 심한 주기곡선을 보이며 거의 에너지를 소산하지 못하였다. 반면 대각배근상세를 갖는 연결보는 핀칭이 없는 안정적인 주기거동을 보이며 많은 에너지를 소산하였으며, 연결보의 에너지소산은 취성재료인 콘크리트보다 주로 대각 방향으로 배치된 철근에 의하여 발생됐다. 이러한 분석 결과를 토대로 대각철근의 변형률 이력을 사용하여 연결보의 에너지소산량을 예측할 수 있는 간편한 평가식을 개발하였다. 검증을 위하여 제안된 평가식과 실험으로 구한 연결보의 에너비소산량을 실험 결과와 비교하였다. 그 결과, 제안된 평가식은 배근형태, 전단경간비, 비탄성 변형 크기 등 다양한 설계변수의 영향을 고려하여 전단경간비가 1.25이하인 짧은 연결보의 에너지소산량을 비교적 정확히 예측하였다. 제안된 에너지소산량 평가 방법은 철근콘크리트구조물 및 부재의 성능 기초 내진평가/설계에 손쉽게 활용될 수 있다

Earthquake-Resistance of Slendor Shear Wall with No Boundary Confinement

Experimental and numerical studies were done to investigate seismic performance of slender shear walls with no boundary confinement that are principal structural members of high-rise bearing wall buildings. 1/3 scale specimens that model the plastic region of long slender shear walls subjected to combined axial load and bending moment were tested to investigate strength, ductility, capacity of energy dissipation, and strain distribution. The experimental results show that the slender shear walls fail due to early crushing in the compressive boundary, and then have very low ductility. The measured maximum compressive strain is 0.0021, much less than 0.004 being commonly used for estimation of ductility. This result indicates that the maximum compressive strain is not a fixed value but is affected by moment gradient along the shear wall height and distance from the neutral axis to the extreme compressive fiber.본 연구는 "97년도 건설기술연구개발사업 제4 세부과제 2차년도 연구"의 연구비 지원으로 수행되었습니다