• Steel and Composite Structures
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• v.26 no.6
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• pp.793-808
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• 2018

In this study, the seismic performance of the connections between L-shaped columns composed of concrete-filled steel tubes (L-CFST columns) and H-beams used in high-rise steel frame structures was investigated. Seven full-scale specimens were tested under quasi-static cyclic loading. The variables studied in the tests included the joint type, the axial compression ratio, the presence of concrete, the width-to-thickness ratio and the internal extension length of the side plates. The hysteretic response, strength degradation, stiffness degradation, ductility, plastic rotation capacity, energy dissipation capacity and the strain distribution were evaluated at different load cycles. The test results indicated that both the corner and exterior joint specimens failed due to local buckling and crack within the beam flange adjacent to the end of the side plates. However, the failure modes of the interior joint specimens primarily included local buckling and crack at the end plates and curved corners of the beam flange. A design method was proposed for the flexural capacity of the end plate connection in the interior joint. Good agreement was observed between the theoretical and test results of both the yield and ultimate flexural capacity of the end plate connection.

• Korean Journal of Construction Engineering and Management
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• v.12 no.3
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• pp.11-21
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• 2011

The most critical issue in free-form buildings is how to construct the free-formed exterior facade panels. Their geometric complexity delivers many cons and problems in fabricating and constructing their shapes. To construct a free-form building, first of all, its skin has to be chopped into small pieces, which is called panelization. After panelization, the panels go through an optimization process to construct them economically. The panel's geometries are modified or regenerated through this optimization process. In this study, the panel optimization process of free-form buildings are performed through a case study. The panel shapes of the case study are modeled with Digital Project. To test the constructability of the various panels, 8 mock-up panels are made and laser scanning technology is applied to measure the preciseness of the panels manufactured in comparison with their original design.

• Korean Journal of Materials Research
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• v.22 no.8
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• pp.416-420
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• 2012

Recently nanoscience and nanotechnology have been studied intensively, and many plants, insects, and animals in nature have been found to have nanostructures in their bodies. Among them, lotus leaves have a unique nanostructure and microstructure in combination and show superhydrophobicity and a self-cleaning function to wipe and clean impurities on their surfaces. Coating films with combined nanostructures and microstructures resembling those of lotus leaves may also have superhydrophobicity and self-cleaning functions; as a result, they could be used in various applications, such as in outfits, tents, building walls, or exterior surfaces of transportation vehicles like cars, ships, or airplanes. In this study, coating films were prepared by dip coating method using polypropylene polymers dissolved in a mixture of solvent, xylene and non-solvent, methylethylketon, and ethanol. Additionally, attempts were made to prepare nanostructures on top of microstructures by coating with the same coating solution with an addition of carbon nanotubes, or by applying a carbon nanotube over-coat on polymer coating films. Coating films prepared without carbon nanotubes were found to have superhydrophobicity, with a water contact angle of $152^{\circ}$ and sliding angle less than $2^{\circ}$. Coating films prepared with carbon nanotubes were also found to have a similar degree of superhydrophobicity, with a water contact angle of 150 degrees and a sliding angle of 3 degrees.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.4
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• pp.31-38
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• 2009

Most 3D models found in the literature focus on theoretical topology for exterior 3D volumes. Although there are a few indoor models such as CityGML or IFC, implementing a full topology for the indoor spaces is either less practical due to the complexity or not even necessary in some application domains. Moreover, current spatial DBMSs do not support functionalities explicitly for 3D topological relations. In this study, an alternative method to build a 3D indoor model with less complexity ernativespatial DBMS is suggested. Focusnation the fact that semantic attributes can be storedion the floor surface, we suggestivemulti-layered 3D model for indoor spaces. We show the process to build the proposed model in the PostGIS, a spatial DBMS. And, then, as an example application, we illustrate the process to build and run a campus building information system.

• Journal of Korean Association for Spatial Structures
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• v.18 no.2
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• pp.59-67
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• 2018

Various pilotis are installed in the lower part of high rise buildings. Strong winds can generate sudden airflow around the pilotis, which can cause unexpected internal airflow changes and may cause damage to the exterior of the piloti ceiling. The present study investigates the characteristics of peak wind pressure coefficient for the design of piloti ceiling exteriors by conducting wind pressure tests on high rise buildings equipped with penetration-type and end-type pilotis in urban and suburban areas. The minimum peak wind pressure coefficient for penetration-type piloti ceilings ranges from -2.0 to -3.3. Minimum peak wind pressure coefficient in urban areas was 30% larger than in suburban areas. In end-type piloti ceilings, maximum peak wind-pressure coefficient ranges from 0.5 to 1.9, and minimum peak wind-pressure coefficient ranges from -1.3 to -3.6. With changes in building height, peak wind pressure coefficient decreases as the aspect ratio increases. Peak wind-pressure coefficient increases with taller pilotis. On the other hand, when piloti height decreases, the absolute value of the minimum peak wind pressure coefficient increases.

• Journal of the Korea Society of Computer and Information
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• v.12 no.3
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• pp.27-35
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• 2007

The majority of farm managers growing the garden products in greenhouse concern massively about the diagnosis and prevention of the breeding and extermination for pests. especially, the managing problem for pests turns up as main issue. In the paper, we first build a wireless sensor network with soil and environment sensors such as illumination, temperature and humidity. And then we design and implement multimedia pest predication and management system which is able to predict and manage various pest of garden products in greenhouse. The proposed system can support the database with information about the pests by building up wireless sensor network in greenhouse compared with existing high-priced PLC device as well as collect various environment information from soil, the interior of greenhouse, and the exterior of greenhouse. To verify the good capability of our system, we implemented several GUI interface corresponding desktop. web, and PDA mobile platform based on real greenhouse model. Finally, we can confirm that our system work well prediction and management of pest of garden products in greenhouse based on several platforms.

• Journal of the Korean Solar Energy Society
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• v.33 no.1
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• pp.89-95
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• 2013

A DBLP(Double blind light pipe) daylight system can be installed at a building exterior wall or roof to replace artificial light during the day time. This system was consisted of a double blind light collector, a mirror duct type light transformer and a prism light pipe distributor. The double blinds were used to track the sun's altitude and azimuth movements to collect the sunlight throughout the day. The sunlight collected by the light collector was reflected on the first mirror and the second mirror and sent to the light pipe through the light transformer. The transformer was designed to deliver the sunlight into the light pipe efficiently. The light distributor plays a role in diffusing the sunlight coming in through the light collector to be used for indoor lighting. In this paper, a DBLP system has been designed, installed and tested at a KIER daylighting twin test cell. The DBLP daylighting system was applied to the experimental test cell which has an indoor area of 2.0 m wide ${\times}$ 2.4 m height ${\times}$ 3.8 m length. The experiment was conducted from January 30 to February 27, 2012, under clear skies and partially cloudy skies. Data was collected from 10:00 am to 16:00 pm every 2 minute and the average was calculated for every 30 minute of the data collection to obtain the system efficiency. The results indicated that the DBLP system efficiency was evaluated as 11.67%. The DBLP system indoor illumination energy reduction was predicted as 0.822 kWh/day. This could replace 4 sets of a 32W fluorescent lamp operating 6.4 hours per a day.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.808-812
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• 2008

Recently, the buildings have been likely to shape Super Tall trend. Therefore, the exterior parts of the buildings come to be changed. Instead of early heavy wall structure, it is changed to light wall concept of curtain wall system. However, the curtain wall system causes lots of loads due to the external surrounding factors of building. In particular, due to the densely built-up condition in Korea, the generation of dew condensation is getting severer Since there has been no standardized process that reviews this generation of dew condensation, it is very urgent for us to prepare the reviewing process for the dew condensation for construction business managers. The purpose of this study is to assess dew condensation function of the curtain wall and provide the basic data for the provision of the future dew condensation review process by comparing and analyzing the range of generation of dew condensation as well as temperature distribution according to the change of relative humidity at the identical temperature by selecting the Unitized system and Stick system which are the representative types of curtain wall system.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.3
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• pp.60-67
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• 2014

Exhaust system used in toilet and cooking place of high riser public house is roof fan of two basic types : natural roof ventilator and natural/forced roof ventilator. Natural/forced roof ventilator has a motor in the rotary shaft. There are many high riser public house in Korea. These buildings were not viewed as being major contributors to exhaust pollutants producted in indoor. It was because many engineers thought that exhaust in high riser building depend on stack effect. This study investigates on stack pressure determined by exterior pressure and the difference pressure control in exhaust stack used in high riser public house. This paper focuses mainly on the effect of the time interval for power supply of motor installed in roof fan with function of natural wind velocity and of exhaust air volume of toilet. It is observed there are higher exhaust efficiency than the existing natural roof ventilator.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.6
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• pp.37-46
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• 2012

In Korea, most existing school buildings have been constructed with moment frames with un-reinforced infill walls designed only considering gravity loads. Thus, the buildings may not perform satisfactorily during earthquakes expected in Korea. In exterior frames of the building, un-reinforced masonry infill walls with window openings are commonly placed, which may alter the structural behavior of adjacent columns due to the interaction between the wall and column. The objective of this study is to evaluate the seismic performance of existing school buildings according to the procedure specified in ATC 63. Analytical models are proposed to simulate the structural behavior of columns, infill walls and their interaction. The accuracy of the proposed model is verified by comparing the analytical results with the experimental test results for one bay frames with and without infill walls with openings. For seismic performance evaluation, three story buildings are considered as model frames located at sites having different soil conditions ($S_A$, $S_B$, $S_C$, $S_D$, $S_E$) in Korea. It is observed that columns behaves as a short columns governed by shear due to infill masonry walls with openings. The collapse probabilities of the frames under maximum considered earthquake ranges from 62.9 to 99.5 %, which far exceed the allowable value specified in ATC 63.