• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.4
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• pp.267-274
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• 1996

This experiment was carried out to investigate the effect of pasture types(mixture and mono tall fescue pasture) and endophyte infection on the animal behavior of Korean native cattle at the Experimental Field of Grassland and Forage Crops Division, National Livestock Research Institute, Suweon, in 1994. The results obtained are sumunarized as follows: DM intake of Korean native cattle was increased with mixture and endophyte-free tall fescue for both pasture types. Mixture and endophyte-free tall fescue showed good animal preference. Daily grazing time was increased with mixture and endophyte-free tall fescue in monoculture, while annual grazing period was increased with monoculture and endophyte-infect tall fescue. Amount of drinking water of Korean native cattle was increased with tall fescue monoculture rather than mixture, however the amount of drinking water was higher with endophyte-infect tall fescue in monoculture. Salt intake of Korean native cattle was increased with mixture and endophyte-6ee tall fescue in monoculture. Rectal temperature of Korean native cattle was not influenced by pasture types and endophyte infection. Based on the results of this experiment, DM intake of Korean native cattle and daily grazing time were increased by mixture and endophyte-free tall fescue with good quality.

• International Journal of High-Rise Buildings
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• v.2 no.2
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• pp.85-91
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• 2013

Tall building has some controversial aspects with low carbon city, but it is still a sensible choice for the metropolitan city. This paper aims to develop holistic urban design strategies to minimize impacts on the environment, increase energy efficiency and improve the quality of living in tall building communities by utilizing tall building characteristics. It puts forward the concept of integrated tall building-low carbon community design from the perspective of urban design, and summarizes five core strategies: Temporal state based on energy use, Complementary energy use state based on functions, Spatial state based on regional environment features, Transportation state based on low-carbon lifestyle and Waste utilization state based on tall building characteristics. It also applies the strategies to a practical project. The results show that the proposed urban design strategies are available approaches to mitigate the side effects of tall building on low carbon city.

• International Journal of High-Rise Buildings
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• v.1 no.2
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• pp.81-85
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• 2012

Vertical meteorological conditions encountered by super tall buildings, such as wind speed, temperature and humidity, vary due to their height. Therefore, it is necessary to consider these environmental changes to properly estimate the heating and cooling loads, and to minimize the energy demands for HVAC in super tall buildings. This paper aims to analyze how vertical meteorological changes affect heating and cooling loads of super tall buildings by using numerical simulation. A radiosonde, which observes atmospheric parameters of upper air such as wind speed, wind direction, temperature, relative humidity and pressure, was used to provide weather data for the building load simulation. A hypothetical super tall building was used for the simulation to provide quantified characteristics of the heating and cooling loads, comparing the lower, middle and upper parts of the building. The effect of weather data on the heating and cooling loads in super tall building was also discussed.

• Wind and Structures
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• v.27 no.6
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• pp.439-449
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• 2018

Wind loading of a tall building built amidst a group of buildings in urban environment is always greatly affected by shielding effects. Wind tunnel tests were carried out to assess the shielding provided by a row of low-rise or medium-rise buildings upstream a square-section tall building of height-to-breadth ratio 6. Mean and dynamic wind loads on the tall building were measured at different wind incidence angles and presented as interference factors (IFs). It is found that presence of a row of upstream buildings provides significant shielding to the tall building. At normal wind incidence, the mean along-wind loads and all components of fluctuating wind loads on the tall building are always reduced by shielding. Vortex shedding seems to still occur on the upper exposed part of the tall building but the vortex excitation levels are largely reduced. The degree of shielding is found to depend on a number of arrangement parameters of the row of upstream buildings. Empirical equations are proposed to quantify the shielding effect based on the wind tunnel data.

• International Journal of High-Rise Buildings
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• v.8 no.1
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• pp.29-36
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• 2019

Tall buildings are one of the most viable solutions to deal with the global phenomenon of rapid population increase and urbanization. While tall buildings are an essential building type to accommodate ever-growing urban population, as buildings become very tall they also produce many critical design challenges related to social interactions, emergency egress, structural systems, etc. While many different design solutions can be sought to resolve these challenging issues of tall buildings, this paper investigates potential of conjoined towers in producing more livable and sustainable megatall building complexes with an emphasis on their capability in efficiently providing exceedingly tall building structures.

• International Journal of High-Rise Buildings
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• v.12 no.4
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• pp.307-320
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• 2023

Tall buildings are built with an abundant amount of materials, including structural materials, coming from our limited natural resources. Tall buildings that began from about 10-story tall office towers have evolved to over 150-story tall mixed-use megastructures. As a building becomes taller, structural material requirement to resist lateral wind loads becomes exponentially larger. Therefore, it is crucial to employ efficient structural systems and optimize their design, which will contribute to sustainable vertical built environments through preservation of resources. Tube type structures with large perimeter diagonals are among the most efficient structural systems for tall buildings. Developments of braced tube, braced megatube, diagrid structures, and their optimal design strategies are reviewed. Superframed conjoined towers, produced by interconnecting multiple clustered braced tubes, are presented as a new design direction to achieve not only structural but also architectural and social sustainable design goals.

• Structural Engineering and Mechanics
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• v.58 no.6
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• pp.967-988
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• 2016

Due to the significant aerodynamic interference from sub-towers and surrounding tall buildings, the wind loads and dynamic responses on main tower of three-tower connected tall building typically change especially compared with those on the isolated single tall building. This paper addresses the wind load effects and equivalent static wind loads (ESWLs) of three-tower connected tall building based on measured synchronous surface pressures in a wind tunnel. The variations of the global shape coefficients and extremum wind loads of main tower structure with or without interference effect under different wind directions are studied, pointing out the deficiency of the traditional wind loads based on the load codes for the three-tower connected tall building. The ESWLs calculation method based on elastic restoring forces is proposed, which completely contains the quasi-static item, inertia item and the coupled effect between them. Then the wind-induced displacement and acceleration responses for main tower of three-tower connected tall building in the horizontal and torsional directions are investigated, subsequently the structural basal and floor ESWLs under different return periods, wind directions and damping ratios are studied. Finally, the action mechanism of interference effect on structural wind effects is investigated. Main conclusions can provide a sientific basis for the wind-resistant design of such three-tower connected tall building.

• International Journal of High-Rise Buildings
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• v.8 no.4
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• pp.235-253
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• 2019

This paper reviews shape optimization studies for tall and super-tall building design. Firstly, shape effects on aerodynamic and response characteristics are introduced and discussed. Effects of various configurations such as corner modifications, taper, setback, openings, and twists are examined. Comprehensive comparative studies on various configurations including polygon building models, and composite type building models such as corner-cut and taper, corner-cut and taper and helical, and so on, are also discussed under the conditions of the same height and volume. Aerodynamic characteristics are improved by increasing the twist angle of helical buildings and increasing the number of sides of polygon buildings, but a twist angle of $180^{\circ}$ and a number of sides of 5 (pentagon) seem to be enough. The majority of examined configurations show better aerodynamic characteristics than straight-square. In particular, composite type buildings and helical polygon buildings show significant improvement. Next, shape effects on pedestrian-level wind characteristics around tall and super-tall buildings are introduced and discussed. Corner modification buildings show significant reductions in speed-up areas. On the other hand, setback and tapered models with wider projected widths near the ground show adverse effects on pedestrian-level wind characteristics.

• International Journal of High-Rise Buildings
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• v.9 no.4
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• pp.387-396
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• 2020

While tall buildings are an essential building type to accommodate an ever-growing urban population, as buildings become taller and taller, many design challenges arise. As floor spaces are repeated vertically, the occupants' natural horizontal circulation-based social interactions are limited. As buildings become ever taller, safe evacuation to the ground level becomes more challenging in emergencies. With respect to safety as well as serviceability, one of the most fundamental design challenges of exceedingly tall buildings is their structural systems that make the physical existence of tall buildings possible. While many different design solutions can be sought to resolve these issues as well as other design challenges of extremely tall buildings, this paper investigates the potential of conjoined towers to create more livable and sustainable vertical environments. Emphasis is placed on the social and structural capabilities of conjoined towers in providing enhanced social interactions and more efficient ultra-tall structures. The related brief history of conjoined towers is presented. To understand their current status, contemporary design practices of conjoined towers are discussed. Lastly, a new concept of superframed conjoined towers developed for exceedingly tall building complexes is introduced through design studies. Though envisioning future tall buildings is challenging, conjoined towers can be among the strong candidates toward more livable and sustainable vertical urbanism.

• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.4
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• pp.275-282
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• 1996

This experiment was canied out to investigate the effect of pasture types(mixture and mono tall fescue pasture) and endophyte infection on the dry matter yield, forage quality and animal performance of pasture plants at the Experimental Field of Grassland and Forage Crops Division, National Livestock Research Institute, Suweon, in 1994. The results obtained are surmmarized as follows : DM yield of tall fescue monoculture was significantly higher(p<0.05) than that of mixture pasture, while DM yield of endophyte-infected pasture was significantly higher(p<0.05) than that of endophyte-free for two pasture types. Crude protein yield(CPY) of tall fescue monoculture was significantly higher(p<0.05) than that of mixture, and the higher CPY with endophyte-infect tall fescue for both pasture types resulted from higher DM yield of the pastures. NDF and ADF contents of pasture plants were not influenced by pasture types, and there was no difference for NDF and ADF contents between endophyte-infect and -free pasture mixture, however, those of pasture plants were increased with endophyte-infect tall fescue in monoculture. IVDMD of pasture plants was increased with mixture and endophyte-free tall fescue for both pasture types. IVDMD of pasture plants was greatly influenced by pasture types and endophyte infection. There were no significant differences in average daily gain of Korean native cattle between pasture types, but those of the cattle were significantly increased with endophyte-free tall fescue for both pasture types(p<0.05). Based on the results of this experiment, it is suggested that a slightly more forage yield could be obtained , from monoculture and endophyte-infected tall fescue. However, liveweight gain was increased by mixture and endophyte-free tall fescue with good quality.