• Proceedings of the Korea Concrete Institute Conference
• /
• 1990.10a
• /
• pp.73-78
• /
• 1990

Large panel building systems are composed of vertical wall panels which support horizontal roof and floor panels to form a box like structure. The simplecity of the connections, which makes precast concrete economically viable, causes a lack of continuity in stiffness, strength and ductility. This precast concrete large panel systems typically have weak connection regions. Three types of 2-story full-scale precast concrete subassemblages were tested under reversed cyclic loading. The seismic resistance capacity and failure mode of each system are compared in connection with the characteristics of joint connection details.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.248-250
• /
• 2003

An automatic approach and strategy for extracting building information from aerial images using combined image analysis and interpretation techniques is described in this paper. A dense DSM is obtained by stereo image matching. Multi-band classification, DSM, texture segmentation and Normalised Difference Vegetation Index (NDVI) are used to reveal building interest areas. Then, based on the derived approximate building areas, a shape modelling algorithm based on the level set formulation of curve and surface motion has been used to precisely delineate the building boundaries. Data fusion, based on the Dempster-Shafer technique, is used to interpret simultaneously knowledge from several data sources of the same region, to find the intersection of propositions on extracted information derived from several datasets, together with their associated probabilities. A number of test areas, which include buildings with different sizes, shape and roof colour have been investigated. The tests are encouraging and demonstrate that the system is effective for building extraction, and the determination of more accurate elevations of the terrain surface.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.11 no.6
• /
• pp.143-152
• /
• 2008

A comparative analysis of rooftop greening in Korea and Japan was carried out to understand current status of rooftop greening creation and technology and to give directions to frame a policy or plan on rooftop greening in Korea. Besides literature studies, questionnaire survey to Korean and Japanese experts on rooftop greening were done. As results, the annual creation areas, the types and the scales of rooftop greening in Seoul and Tokyo until 2007 were analysed and the satisfaction on the creation areas and technologies, the preference types, the present levels of and the most important parts among policies (support systems), technologies (creation methods), materials, maintenances and user programs for the development or expansion of rooftop greening in Korea and Japan were compared. The creation areas of rooftop greening in Seoul until 2007 was around 15% in Tokyo but the increasing rate of those in Seoul was faster than in Tokyo. Korean needs for the improvement on the rooftop greening systems and technologies were higher than Japanese, but both desired the expansion of rooftop greening areas in both countries. Korean preferred semi-intensive rooftop greening system but Japanese preferred intensive system. Korean and Japanese rooftop greening experts preferred policies (support systems) and technologies (creation methods) for the most important part for the development or expansion of rooftop greening in both countries.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2009.05a
• /
• pp.524-528
• /
• 2009

The objectives of this study were to install RCR systems at a typical single family house and a school in Alabama, and evaluate the feasibility and efficiency of using the RCR systems for water harvesting in Alabama. The RCR systemswere equipped with a control system and a CR10X data logger to monitor the system operation and to collect data on precipitation, temperature, overflow, water depth in the storage tank and daily uses of toilet flushing. Daily average water use of the home for toilet flushing was 95 liter and 2100 liter was used at the school during the school days. Rainwater harvesting efficiency was 83.3 and 89 percent and RCR use efficiency was 18 and 98 percent from the home and the school, respectively. A computer program was developed to estimate potential effectiveness of RCR systems. From the analysis result with 10 years rainfall data, a total of 67,000 liters of rainwater could be harvested for domestic uses from a typical single family house which supplies 190 liters per day.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.21 no.6
• /
• pp.311-322
• /
• 2017

In this study, the seismic performance of concrete-steel composite moment frame structures equipped with seismic retrofitting systems such as seismic reinforcement, base isolators, and bracing members, which are typical earthquake damage mitigation systems, is evaluated through nonlinear dynamic analyses. A total of five frame models were designed and each frame model was developed for numerical analyses. A total of 80 ground acceleration data were used to perform the nonlinear dynamic analysis to measure ground shear force and roof displacement, and to evaluate the behavioral performance of each frame model by measuring inter-story drift ratios. The analysis results indicate that the retrofitting device of the base isolator make a significant contribution to generating relatively larger absolute displacement than other devices due to flexibility provided to interface between ground and column base. However, the occurrence of the inter-story drift ratio, which is a relative displacement that can detect the damage of the structure, is relatively small compared with other models. On the other hand, the seismic reinforced frame model enhanced with the steel plate at the lower part of the column was found to be the least efficient.

• Wind and Structures
• /
• v.4 no.3
• /
• pp.213-226
• /
• 2001

Wind uplift rating of roofing systems is based on standardised test methods. Roof specimens are placed in an apparatus with specified table size (length and width) then subjected to the required wind load cycle. Currently, there is no consensus on the table size to be used by these testing protocols in spite of the fact that a table size plays a significant role in evaluating the performance. This paper presents a study with the objective to investigate the impact of table size on the performance of roofing systems. To achieve this purpose, extensive numerical experiments using the finite element method have been conducted to investigate the performance of roofing systems subjected to wind uplift pressures. Numerical results were compared with results obtained from experimental work to benchmark the numerical modeling. Required table size and curves for the determinations of appropriate correction factors are suggested. This has been completed for various test configurations with thermoplastic waterproofing membranes. Development of correction factors for assemblies with thermoset and modified bituminous membranes are in progress. Generalization of the correction factors and its usage for wind uplift rating of roofs will be the focus of a future paper.

• Journal of Korean Association for Spatial Structures
• /
• v.20 no.4
• /
• pp.141-147
• /
• 2020

Single-layered grid space steel roof structure is an architectural system in which the structural ability of the nodal connection system greatly influences the stability of the entire structure. Many bolt connection systems have been suggested to enhance for better construct ability, but the structural behavior and maximum resistance of the connection system according to the size of bolt clearance play were difficult to identify. In particular, the identification of bending stiffness of the connection system is very important due to the characteristics of shell structures in which membrane stresses based on bending force effect significantly. To identify effective structural behavior and maximum bearing force, four representative nodal connection systems were selected and nonlinear numerical analysis were performed. The numerical analysis considering the size of the bolt clearance were performed to investigate structural behavior and maximum values of the bending force. In addition, the type of effective nodal connection system were evaluated. As a result, the connection system, which has two shear plane, represented high bending stiffness.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.12 no.2
• /
• pp.69-80
• /
• 2008

In this study, improved capacity spectrum method (CSM) is proposed. The method can account for higher mode contribution to the seismic response of MDOF systems. The CSM has been conveniently used for determining maximum roof displacement using both demand spectrum and capacity curve of equivalent SDOF system. Unlike the conventional CSM, the maximum roof displacement is determined without iteration using inelastic displacement ratio and R factor calculated from demand spectrum and capacity curve. Three moment resisting steel frames of 3-, 9- and 20-stories are considered to test the accuracy of the proposed method. Nonlinear response history analysis (NL-RHA) for three frames is also conducted, which is considered as an exact solution. SAC LA 10/50 and 2/50 sets of ground motions are used. Moreover, this study estimates maximum story drift ratios (IDR) using ATC-40 CSM and N2-method and compared with those from the proposed method and NL-RHA. It shows that the proposed CSM estimates the maximum IDR accurately better than the previous methods.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.1
• /
• pp.1-7
• /
• 2015

A gutter is generally a fixed beneath the edge of a roof to carry off rainwater, or a narrow trough that collects rainwater from the roof of a building to diverts it from the structure, typically into a drain. Reasonable designs reduce the mass of the gutters (~ 16.9%), make it faster and easier to assemble, and gives it consistent strength and integrity (about 10%). New gutter systems are presented according to the results of structural analyses performed by ANSYS and ADAMS/Durability Hot Spots. In addition, the CATIA program can improve the precision of the 3D system simulations. The design of a gutter system installations also needs to comply with the specific rainfall intensities and adequate overflow provisions needs to be provided to prevent water from sides of the roofs during heavy rainfall periods. The principle outcome of this work is a computational design tool that can be used to improve the gutter performance considering a variety of factors (gutter geometry, drainage and rainfall intensity). A good gutter design must satisfy many criteria, including durability, low cost, and ease of repair and cleaning.

• Journal of Bio-Environment Control
• /
• v.23 no.3
• /
• pp.181-191
• /
• 2014

Modern commercial greenhouse requires the use of advanced climate control system to improve crop production and to reduce energy consumption. As an alternative to classical sensor-based control method, this paper introduces a model-based control method that consists of two models: the predictive model and the evaluation model. As a first step, this paper presents straightforward models to predict the effect of natural ventilation in a greenhouse according to meteorological factors, such as outdoor air temperature, soil temperature, solar radiation and mean wind speed, and structural factor, opening rate of roof ventilators. A multiple regression analysis was conducted to develop the predictive models on the basis of data obtained by computational fluid dynamics (CFD) simulations. The output of the models are air temperature drops due to ventilation at 9 sub-volumes in the greenhouse and individual volumetric ventilation rate through 6 roof ventilators, and showed a good agreement with the CFD-computed results. The resulting predictive models have an advantage of ensuring quick and reasonable predictions and thereby can be used as a part of a real-time model-based control system for a naturally ventilated greenhouse to predict the implications of alternative control operation.