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Wind tunnel tests of 3D wind loads on tall buildings based on torsional motion-induced vibrations

  • Zou, Lianghao;Xu, Guoji;Cai, C.S.;Liang, Shuguo
    • Wind and Structures
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    • v.23 no.3
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    • pp.231-251
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    • 2016
  • This paper presents the experimental results of the wind tunnel tests for three symmetric, rectangular, tall building models on a typical open terrain considering the torsional motion-induced vibrations. The time histories of the wind pressure on these models under different reduced wind speeds and torsional amplitudes are obtained through the multiple point synchronous scanning pressure technique. Thereafter, the characteristics of both the Root Mean Square (RMS) coefficients and the spectra of the base shear/torque in the along-wind, across-wind, and torsional directions, respectively, are discussed. The results show that the RMS coefficients of the base shear/torque vary in the three directions with both the reduced wind speeds and the torsional vibration amplitudes. The variation of the RMS coefficients in the along-wind direction results mainly from the change of the aerodynamic forces, but sometimes from aeroelastic effects induced by torsional vibration. However, the variations of the RMS coefficients in the across-wind and torsional directions are caused by more equal weights of both the aerodynamic forces and the aeroelastic effects. As such, for the typical tall buildings, the modification of the aerodynamic forces in the along-wind, across-wind, and torsional directions, respectively, and the aeroelastic effects in the across-wind and torsional directions should be considered. It is identified that the torsional vibration amplitudes and the reduced wind speeds are two significant parameters for the aerodynamic forces on the structures in the three directions.

Future Directions and Perspectives for Performance Assessment in Mathematics (수학과 학업성취도 평가를 위한 수행평가의 과제와 전망)

  • 성태제;권오남
    • School Mathematics
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    • v.1 no.1
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    • pp.217-234
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    • 1999
  • The first part of this paper examines the assumptions underlying traditional types of standardized testing compared with assumptions underlying innovative types of performance assessment. The second part focuses on directions for the future. The third part gives examples from closed related projects which were designed to find practical ways to implement recommendations.

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Directions for Eco-friendly Utilization and Industrialization of Fishery By-products (수산부산물의 발생·처리 실태 및 산업화 방향)

  • Kim, Dae-Young;Lee, Jung-Sam
    • Journal of Fisheries and Marine Sciences Education
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    • v.27 no.2
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    • pp.566-575
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    • 2015
  • The study aims to identify the generation and treatment of fishery by-products in Korea and suggests future directions and strategies for their eco-friendly utilization and industrialization. First, the study focuses on the identification of the generation and their treatment in Korea since merely few study were conducted and they did not provide enough information regarding the overall generation and treatment at the national level. According to the estimation, Korea generates 800 thousand to 1,200 thousand tones of fishery by-product every year. The fishery by-products generated at large seafood markets and processing facilities are used or processed as fish meal and feed, but those generated from households and small seafood restaurants are currently treated as food waste. In addition, inadequately treated fishery by-products cause various problems such as spoiling urban landscape, creating odor and incubating pest. After identifying the generation and treatment of fishery by-products, the study suggests directions for the formulation of infrastructure for transition into resource circulation society, minimization of dumped waste and their eco-friendly recycling as resources, diversification of recycled goods and development into a high-value added industry. Finally, the study suggests detailed strategies for the directions such as establishment of legal and institutional foundation, separation of fishery by-products from wastes, development of technology tailored for commercialization, introduction of pilot projects for industrialization and cultivation of social enterprises.

A Study on Establishment of the Directions for Environmentally-friendly Restoration of Underground Stream by Citizen Participation - In the Case of the Yangjae Underground Stream Restoration Project - (주민참여를 통한 도시복개하천의 환경친화적 복원방향설정에 관한 연구 - 과천 양재천 복개하천 복원사업을 사례로 -)

  • Song, Byeong Hwa;Yang, Byoung-E
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.9 no.2
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    • pp.33-44
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    • 2006
  • The purpose of this study is to establish future directions of environmentally-friendly restoration of Yangjae underground stream and reflect various opinions of inhabitant in the plan and design process. The opinions from the citizens include the economic and environmental suitability of the restoration projects and preference for the future directions of restoration. The citizens are favorable to removing the existing parking lot and want to have jogging course, walking path and bike road in the stream. Different opinions and resulted in preferred facilities and diminishing existing park along the stream depending on the restoration influencing zone. As a result, citizens agree in restoration but they have different opinions about the feasibility of new facilities, streams restoration and central park reduction locally. It is desirable to reflect the opinions of citizens in the process of plan and design of restoration project.

Determination of Driving Rain Index by Using Hourly Weather Data for Developing a Good Design of Wooden Buildings

  • Ra, Jong Bum
    • Journal of the Korean Wood Science and Technology
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    • v.46 no.6
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    • pp.627-636
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    • 2018
  • This research was performed to supplement the previous research about the driving rain index (DRI) for Korea determined by using daily weather data for 30 years. The average annual driving rain index (AADRI) was calculated from the hourly weather data, and the magnitude of DRI was investigated according to wind directions. The hourly climate data were obtained from the Korea Meteorological Administration (KMA) for the period 2009 to 2017. Of 82 locations investigated, seven were classified into regions where the level of exposure of walls to rain was high. The result showed quite a difference from the previous results, in which no high exposure regions were observed. Since the hourly-based and the daily-based annual driving rain index (ADRI) values showed only a slight difference, the result may be explained by the length of the periods used in both studies. The change of DRI according to wind directions showed that there was a certain range of wind directions in which driving rain easily approached building walls. It suggests that the consideration of wind directions with high DRI would be useful to develop a good design of wooden buildings from the point of wood preservation and maintenance.

A Proposal on Dormitory furniture Design for University Students - Focusing on Dorm Units - (대학교 기숙사가구 디자인방향 제안 - 기숙사 개인실을 중심으로 -)

  • Park, Young-Soon;Jung, Eui-Chul;Kim, Eun-Jeong;Oh, Se-Hwan
    • Korean Institute of Interior Design Journal
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    • v.17 no.6
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    • pp.197-206
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    • 2008
  • This study aimed to suggest practical and useful design directions for furniture for the rapidly-increasing university dormitory population. The process of the study took four steps; theoretical research, in-depth interview based on questionnaire, analysis, and development of design directions. Interviews were conducted with 25 university students living in dormitories in Seoul to find out problems with the existing furniture, students' satisfaction with the furniture, and their needs for other options. From these interviews, we found a few problems with dorm units, such as insufficient storage space, spaces too small for privacy, monotonous & standardized furniture design, and lack of multi-purpose furniture, etc. To support college students' complex lifestyles, five design directions were suggested from the analysis, such as a furniture design with highly multiple uses, modular furniture design, sufficient storage space, an application of various colors & materials, and practical use of dead space. Among these, two items were selected to be manufactured by the furniture design company. We expect that our suggested design directions for dorm furniture will support students' complex lifestyles, and satisfy students' needs with highly enhanced and better designed environments.

Development of Evaluation Indices for Redundant Farmlands Rehabilitation-Policy Directions (유휴농지의 활용방향 설정을 위한 평가지표 개발)

  • Bae, Seung-Jong;Yoon, Seong-Soo;Han, Yi-Cheol;Yoon, Hong-Il
    • Journal of The Korean Society of Agricultural Engineers
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    • v.52 no.5
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    • pp.97-108
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    • 2010
  • The objective of this study is to develop evaluation indices which can be applied to analyze rational rehabilitation-policy directions of redundant farmlands. To achieve this objective, the main tasks of this research are 1) categorizing the redundant farmlands rehabilitation types 2) developing the evaluation indices of redundant farmlands rehabilitation 3) determining the weights of each index. The redundant farmlands rehabilitation types were classified into agricultural rehabilitation type, non-agricultural rehabilitation type and hybrid type which are called by agricultural income model, rural environment improvement model and hybrid model as development project name, respectively. The 5 parts and 21 indices for evaluation of redundant farmlands rehabilitation directions were extracted by case studies and experts brainstorming. The weights of each index were determined by Analytic Hierarchy Process (AHP). The developed evaluation indices were applied to study areas located on Yanghwa district of Gongju-city and Aewol district of Jeju-city. From the results of this study, it was ascertained that the evaluation indices developed in this study would help the decision-makers in the planning process of redundant farmlands rehabilitation directions.

A Direction-of-Arrival Estimation Based Adaptive Beamforming Algorithm for OFDMA Smart Antenna Systems (OFDMA 스마트 안테나 시스템을 위한 도래각 추정 기반의 적응 빔 형성 알고리즘)

  • Yun, Young-Ho;Park, Yoon-Ok;Park, Hyung-Rae
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.12A
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    • pp.1214-1222
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    • 2006
  • In this paper, an efficient direction-r)f-arrival based adaptive beamforming algorithm for orthogonal frequency-division multiple-access smart antenna systems is proposed. The proposed algorithm provides a high performance by steering main beams to the directions of a desired signal, whereas steering nulls to the directions of the interference, using the estimated directions. The beamforming outputs obtained by steering the main beams to the distinct directions of resolvable multipath signals are combined in a maximal ratio manner to exploit angular diversity gain. The performance elf the proposed algorithm is finally evaluated in cellular mobile environments to verify its efficiency and is compared with that of least-squares beamforming algorithm, by taking the WiBro system as a target system.