• KIEAE Journal
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• v.13 no.5
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• pp.111-118
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• 2013

This study aims to investigate advantages of complex installation of green roof and PV system in a public building, to analyze the impact of green roof on the efficiency of PV power generation, and to consider the correlation between green roof and PV power generation. When the temperature and power generation of the modules installed in the green roof and non-green roof of the public building were measured for 3 days, the average temperature of the green roof was 23.6 degrees, and it was 36.1 degrees in the non-green roof which increased by nearly 53%. Overall, the module temperature in the green roof was lower. On the other hand, in relation to the PV generation depending on temperature reduction during the same period, the mono-crystalline module and the poly-crystalline module in the green roof showed an increase in generation at nearly 222.2W and 341.6W, and the efficiency rose by 5.5% and 6.2%, respectively, compared to the modules in the non-green roof. Therefore, it is analyzed that green roof has a positive influence on PV power generation. Finally shows the efficiency of the installed on the Green Roof PV system (complex Installation) higher than on the concrete roof PV system. Thus, the complex PV systems as well as the usual benefits of green roofs will provide greater synergies.

• Wind and Structures
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• v.39 no.4
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• pp.259-269
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• 2024

The current research on the wind resistance of standing seam metal roofs primarily focuses on the failure modes of the entire roof panel and the contact areas between the seams and supports, with little consideration given to the synergy between the roof seam reinforcements, the web, and the supports. As a result, the failure mechanisms of roof systems cannot be accurately represented. This paper, based on wind uplift tests and ABAQUS simulation modeling, provides a detailed analysis of the wind resistance and failure mechanisms of reinforced standing seam metal roof systems. The study reveals that the deformation and failure of the roof system under wind load can be divided into three stages: elastic deformation, plastic deformation, and failure. In the elastic deformation stage, the areas with higher stress are mainly distributed in the mid-span of the roof panels and along the ribs, where the roof stress remains below the material's yield strength, and the displacement at the roof panel seams is minimal. During the plastic deformation stage, as the load increases, significant vertical deformations appear in the roof panels, the lateral displacement at the seams gradually increases, and the stress growth is pronounced. Without reinforcement, the roof panel withstands a maximum wind pressure of 3.2 kPa, with a central vertical displacement of 109 mm, while the ultimate lateral displacement at the seams reaches 2.3 mm, resulting in unseating failure, marking the structural failure. With reinforcement, the roof panel can withstand a maximum wind pressure of 4.3 kPa, corresponding to a central vertical displacement of 122 mm. The growth of lateral displacement at the seams slows down, and the reinforcement significantly suppresses seam displacement. As the load continues to increase, the reinforcements and the web work synergistically, exhibiting reciprocating counterclockwise and clockwise rotations, with the maximum lateral displacement at the seams increasing to 3.05 mm. Ultimately, unseating occurs at the roof panel seams or tearing at the web. Therefore, the reinforcement system significantly enhances the wind resistance of the roof system, providing theoretical guidance for wind-resistant design in roofing engineering.

• KIEAE Journal
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• v.14 no.2
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• pp.11-19
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• 2014

Building energy consumption takes up almost 25% of the total energy consumption. Therefore, diversified ways, such as improving wall and window insulation, have been considered to reduce building energy consumption. Recently, green roof system has been explored as an effective alternative for dealing with reducing heating and cooling energy, thermal island effect and improving water quality. However, recent studies regarding a green roof system have only focused on building energy reduction without considering the applied usage, location, and story of the green roof system. Therefore, this study pays attention to the heating and cooling energy in relation to the applied usage, location, and story of a green roof system for investigating its impact on energy reduction. The result of simulations show that the reduction in heating energy consumption is higher when applied to Cherwon-gun province which has a continental climate condition, compared to the city of Busan that is distinguished by its warm climate. Cooling energy saving turns out to be higher when the green roof system is applied to Busan in comparison with Cherwon. As for the applied usage or function of the building, residential space acquires the highest heating and cooling energy saving effect rather than commerce, educational or office space because of HVAC's running time based on usage. When it comes to the story of the green roof, both heating and cooling energy saving become the highest when the green roof is applied to single-storied buildings. The reason is that single story building is affected by the ground largely. Generally, the variations of heating energy consumption are larger than the cooling energy consumption. The outcome of the simulations, when a green roof system is applied, indicates that the energy consumption reduction rate is dynamically responding to the applied usage, location, and story. Therefore, these factors should be counted closely for maximizing the reduction of energy consumption through green roof systems.

• Structural Engineering and Mechanics
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• v.8 no.2
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• pp.165-180
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• 1999

The cost effectiveness of using steel roof systems for residential buildings is becoming increasingly apparent with the decrease in manufacturing cost of steel components, reliability and efficiency in construction practices, and the economic and environmental concerns. While steel has been one of the primary materials for structural systems, it is only recently that its use for residential buildings is being explored. A comprehensive system for the design of residential steel roof truss systems is presented. In the first stage of the research the design curves obtained from the AISI-LRFD code for the manufactured cross-sections were verified experimentally. Components of the truss systems were tested in order to determine their member properties when subjected to axial force and bending moments. In addition, the experiments were simulated using finite element analysis to provide an additional source of verification. The second stage of the research involved the development of an integrated design approach that would automatically design a lowest cost roof truss given minimal input. A modified genetic algorithm was used to handle sizing, shape and topology variables in the design problem. The developed methodology was implemented in a software system for the purpose of designing the lowest cost truss that would meet the AISI code provisions and construction requirements given the input parameters. The third stage of the research involved full-scale testing of a typical residential steel roof designed using the developed software system. The full scale testing established the factor of safety while validating the analysis and design procedures. Evaluation of the test results indicates that designs using the present approach provide a structure with enough reserve strength to perform as predicted and are very economical.

• Journal of the Korean Solar Energy Society
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• v.26 no.1
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• pp.73-79
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• 2006

The integration of PV modules into building facades or roof could raise PV module temperature that results in the reduction of electrical power generation. Lowering operating temperature of PV module is important in this respect, and PV module temperature should be considered more accurately, for building-integrated PV(BIPV) systems in predicting their performance. This paper describes a BIPV solar roof design and verifies its performance through experiment In relation to the effect of ventilation in space between PV module and roof surface. The results showed that the ventilation in the space had a positive effect in lowering the module temperature of the BIPV solar roof that enhanced the performance of its electricity generation.

• KIEAE Journal
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• v.3 no.3
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• pp.3-11
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• 2003

The purpose of this study is to develope an available outdoor insulation construction for the green roof system in Korea. On its own economical and structural problems of constructional risk, the typical outdoor insulation construction on the korean spot does not function efficiently with the green roof. Therefore, this study consists of four main contents as follows: 1. The objectives of the study are established by analysing the problems of the typical in- and outdoor roof insulation system in korea. 2. The foreign outdoor insulation systems for the green roof are clarified to find out an acceptable prototype for Korea. 3. According to loadtest, the prototype, which has a waterproof on the thermal insulation, is tested to demonstrate the structural safety. 4. The U-value test of the prototype on KS F 2277 brings the thermal performance of the green roof system, which can influence the thickness of the insulation.

• Journal of Korean Association for Spatial Structures
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• v.17 no.1
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• pp.31-40
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• 2017

The objective of this study is to analysis the mechanical characteristics and nonlinear behaviors on the geometric nonlinear behavior of a cable spoke wheel roof system for long span lightweight roof structures. The weight of a cable spoke wheel roof dramatically can reduce and the cable roof system can easily make the required rigidity and shape by the sag ratio and pretension forces. Determining the pretension and initial sag of cable roof system is essential in a design process and the shape of roof is changed by pretension. The nonlinear behavior of flexible cable system has greatly an affect on the sag and pretension. This paper will be carried out analyzing and comparing the tensile forces and deflection of a cable spoke wheel system for the large span retractable roof, and analyzed to deflections and tensile forces by the post height of center hub. The double arrangement of a spoke wheel system with reverse curvature works more effectively as a load bearing system, the pretension can easily increase the structural stiffness. The cable truss system can carry vertical load in up and downward direction, and act effectively as load bearing elements.

• Journal of Korean Living Environment System
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• v.21 no.6
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• pp.959-964
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• 2014

Energy performance of building envelope components, including external walls, floors, roofs, windows and doors, is crutial for determining how much energy is required for heating and cooling in a building. Among various building technologies, a green roof system can be a good option for reducing heat gain and loss in new buildings as well as existing buildings for green remodeling. This paper evaluates the performance of green roof systems according to soil depth and Leaf Area Index (LAI) for existing buildings. It also attempts to quantify the energy saving effects on new and existing buildings with different insulation levels. Thermal performance of green roofs is mainly dependent on soil thickness and LAI. Installation of green roofs in deteriorated existing buildings can lead to improvements in roof insulation, due to the soil layer. An increase in soil depth leads to a decrease in heating load, regardless of conditions of vegetation on the green roof. Larger LAI values may reduce cooling loads in the cooling season. Installation of green roof in deteriorated existing buildings showed bigger energy saving effect in comparison to a case in new buildings. A simulation study showed that the installation of green roof systems in deteriorated existing buildings with low insulation levels, due to low thermal performance requirements when constructed, could improve the energy performance of the buildings similar or better to the peformance on new buildings with the most updated insulation standard. Thus, when remodeling a deteriorated building, green roofs could be a good option to meet the most recent energy requirements.

• Journal of KSNVE
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• v.9 no.4
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• pp.822-827
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• 1999

The reduction of booming noise level and improvement of sound quality in the vehicle interior have been major fields of vehicle NVH for many years. In order to reduce the booming noise this paper proposed a system variable, which takes account of mode shapes and natural frequencies of the structural-acoustic system, measurement points and excitation frequency. By simplifying the system variable, the major contributors of panels inculding roof, roof lining, wind shield glasses, doors and floor to booming noise at a specific frequency was experimentally found. Also the relationships between structural modes of roof lining, one of the major contributors, and acoustic modes of compartment cavity were investigated from the viewpoint fo structure-borne noise. In addition, the roof lining was modified structurally by applying marble sponge to the gap between roof and roof lining. Asthe result of structural modification, the booming noise was reduce at target frequency.

• Journal of Korean Association for Spatial Structures
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• v.18 no.1
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• pp.93-100
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• 2018

The retractable roof structures have actions of various types of loads and external forces depending on the retraction and operation conditions of the roof in terms of efficiency of control and maintenance as the aspect of structural plan. In particular, there is a need for studies on the establishment of retraction controlled wind velocity to maintain the stable control and usability of roof structure against strong winds or sudden gusts during the retraction of the roof. In this paper, it was intended to provide basic materials for the development of guidelines on the operation and maintenance of domestic retractable buildings with large space by analyzing the factors affecting the retraction controlled wind velocity for the overseas stadiums with the large spatial retractable roof structures where the sliding system was applied on the steel retractable systems. As a result, the controlled wind velocity tends to decrease as the retractable roof area increases. On the other hand, the controlled wind velocity tends to increase as the retraction time increases. In addition, in the space-grid roof structures, the spherical roof structures type showed the average controlled wind velocity of 10m/sec lower than that of 17.3m/sec for curved-roof structure type, and in the curved-roof structure type, the truss roof structure showed the average controlled wind velocity of 8.9m/sec which is lower than that of 17.3m/sec for the space for the space-grid roof structure.