• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1307-1316
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• 2009

In this case, powerfulness quorum of destruction side which we have expected are supposed general limit value for rock floor when retaining of earth on the section of rock floor in the urban area. For digging in the urban area, there are a lot of dislocations to be disadvantage for safety of digging ants. The displacement of the pondside didn't converged with the phase of the excavation. Also, the speed of displacement got higher than the percentages of risk in the construction. So, we put into operation Face mapping for checking special quality of dislocations which appear on the digging ants. This results were used to decide a destruction in the case of the final excavation by analyzing with other results. It was possible to know the unstable distribution of a fault line in Face Mapping and to get powerful lens of a surface of discontinuity by tests indoors and outdoors. The results were also used to make a solution. Therefore, It's a successful example using the Partial TopDown for stable digging. And it is important that Face Mapping have to be practiced for solving the uncertainty of ground organization when digging design in the urban city.

• Computers and Concrete
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• v.28 no.5
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• pp.497-506
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• 2021

Steel-concrete composite structures and precast concrete elements have a common prefabrication process and allow fast construction. The use of hollow-core slabs associated with composite floors can be advantageous. However, there are few studies on the subject, impeding the application of such systems. In this paper, a numerical model representing the considered system using the FE (finite element)-based software DIANA is developed. The results of an experimental test were also presented in Souza (2016) and were used to validate the model. Comparisons between the numerical and test results were performed in terms of the load versus displacement, load versus slip, and load versus strain curves, showing satisfactory agreement. In addition, a wide parametric study was performed, evaluating the influence of several parameters on the behaviour of the composite system: The strength of the steel beam, thickness of the web, thickness and width of the bottom flange of the steel beam and concrete cover thickness on top of the beam. The results indicated a great influence of the steel strength and the thickness of the bottom flange of the steel beam on the capacity of the composite floor. The remaining parameters had limited influences on the results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.4
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• pp.108-118
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• 2006

The purpose of this study is to investigate the effectiveness of a LQG Hybrid controller to suppress the earthquake disturbance for the building structure. The ground acceleration of N-S component of El-Centro earthquake was scaled to confirm that the building behaved within the elastic range. The tuned mass damper(TMD) on the top floor regulated by LQG algorithm was designed to control the floor displacements. The displacement responses of the hybrid control were compared with those obtained from an active control along with a passive control. The results showed that the LQG hybrid control used approximately 50% less input forces than an active control to satisfy the performance criteria.

• Korean Institute of Interior Design Journal
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• v.21 no.1
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• pp.258-268
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• 2012

The bathroom is a space where humans fulfil certain daily needs, but for the disabled, it can be the most difficult space to use and may even be a cause of accidents and a source of danger. Previous studies on the bathroom have mostly proposed an ideal model of bathroom, but the majority of disabled people live in small homes of about $50m^2$ in size. As their bathrooms are usually very small, and existing houses have various structural limitations, more research should be conducted on the remodeling of residential bathrooms. This study analyzed a number of remodeling items in bathrooms, all of which were listed in previous studies. Based on 17 cases of residential bathroom remodeling in the homes of disabled people residing in Incheon in 2009, this study analyzed several remodeling items required according to the subject's characteristics, such as a lifestyle, gender, and family composition; and proposed the following remodeling requirements and improvement measures for ambulatory-disabled persons and sedentary-disabled people. First, as ambulatory-disabled people have lower-limb impairments, they required bathroom remodeling designed to improve their mobility in the bathroom. These subjects desired the installation of grab bars, as well as the elimination of floor level differences, the installation of non-slip flooring, a counter-top, a sink stand, and a shower holder whose height can be adjusted. Second, sedentary-disabled people move around in a sitting or crawling position, so many of them asked to eliminate floor level differences and vertically-installed bathroom furnishings. Basically, both people with ambulatory disabilities and people with non-ambulatory impairments requested the elimination of floor level differences and the installation of non-slip flooring and grab bars for the toilet and bathtub. They also asked for the heights of sinks, faucets, mirrors, shower holders, and cabinets to be adjusted to suit their needs.

• Journal of Environmental Health Sciences
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• v.35 no.5
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• pp.355-361
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• 2009

This study evaluated the bacterial concentrations and affecting factors at the laboratories of a university in Seoul, Korea. Thirty-three samples of total airborne bacteria (TAB) and eighteen samples of gram negative bacteria (GNB) were collected from both microbiology laboratories (7) and chemistry laboratories (6). GM (GSD) of TAB and GNB concentrations were 194 (2.52) $cfu/m^3$, 24 (4.1) $cfu/m^3$, respectively. TAB concentrations in the chemical laboratories (GM (GSD): 193 (2.0) $cfu/m^3$) were not significantly different from those in microbial laboratories (GM (GSD): 202 (2.7) $cfu/m^3$, (p>0.05)). GM (GSD) of TAB concentrationsat the top of sink, the center of laboratory, and the front of ventilation ventilation device within laboratories, 182 (3.2) $cfu/m^3$, 217 (2.2) $cfu/m^3$, 176 (2.4) $cfu/m^3$, respectively, were not significantly different (p=0.48). Related factors were measured such as temperature, relative humidity, floor of laboratory, number of persons and laboratory area. TAB concentrations were significantly related to temperature (r=0.36, p<0.05), and the floor of laboratory and temperature were also significantly related (r=0.49, p<0.001). However, other factors such as relative humidity, number of persons and laboratory area did not show any significant relationship with TAB concentrations (p>0.05). TAB concentrations were affected significantly by cleaning frequency (p<0.001) and floor of laboratory (p<0.05). There was also a significant difference (p<0.01) between TAB indoor concentrations and TAB outdoor concentrations. However, other factors such as general ventilation did not affect TAB concentrations (p>0.05) in this study.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.879-882
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• 2008

The market of Korea of post-tension system for building is growing up since 2000 and many engineers and construction companies show interest in it. This paper introduces the structure system and construction of post-tension tall buildings including recent trend in the industry of post-tension system for buildings in Korea and the point to be considered when design post-tensioned tall building. Park Polis is composed of two towers of 39 stories with a level to the top of the roof +144m and is currently under construction at Ulsan in Korea. This building designed as the unbonded post-tension floor system and will be the tallest and first high-rise post-tensioned building in Korea. The structural system is composed of the flat slabs, perimeter columns and core walls. At first, this building had designed as regular RC flat slab with perimeter beams. However, floor structure system was reconsidered because the construction company wants to improve efficiency of construction. As a result, the floor system of PARK POLIS re-designed as PT flat slab.

• Smart Structures and Systems
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• v.14 no.4
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• pp.595-615
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• 2014

This study aims to investigate the relationship between structural damage and sensitivity indices using the Hilbert-Huang transform (HHT) method. Two damage detection indices are proposed: the ratio of bandwidth (RB), and the ratio of effective stiffness (RES). The nonlinear four bays multiple degree of freedom models with various predominant frequencies are constructed using the SAP2000 program. Adjusted PGA earthquake data (Japan 311, Chi-Chi 921) are used as the excitations. Next the damage detection indices obtained using the HHT and the fast Fourier transform (FFT) methods are evaluated based on the acceleration responses of the structures to earthquakes. Simulation results indicate that, the column of the 1 st floor is the first yielding position and the RB value is changed when the RES<90% in all cases. Moreover, the RB value of the 1 st floor changes more sensitive than those from the top floor. In addition, when the structural response is nonlinear (i.e., RES<100%), the RB and the RES curves indicate the incremental change in the HHT spectra. However, the same phenomenon can be found from FFT spectra only when the stiffness reduction is large enough. Therefore, the RB estimated from the smoothed HHT spectra is an effective and sensitive index for detecting structural damage.

• Journal of architectural history
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• v.17 no.4
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• pp.97-112
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• 2008

In this study, I attempted to the architectural design characteristics of Daeung-Jeon in Sudeok Temple. For this purpose, After I set up several assumptions in the basis of the general characteristics of Korean wood architecture, and then, analyzed floor plan, structural formation and section sizes of structure and bracket members in relation to module and unit. As the results, the characteristics of the design process of plan and structure are follows. (1) 1 ja(尺), the unit applied to this building is measured $307.6{\sim}318.3mm$) and the average is 312.9mm (2) It is estimated that the floor plan designed on the basis of the top of columns. By the applied unit, every bay of the front side and the side is each designed by 15 ja and 8.5 ja. (3) The section is composed of piled members which have same section size. As basic module of section size called 'jae(재;材)', it is estimated at width 0.45 ja by height 0.75 ja. And as the secondary module, height between jae and is called 'gyoe(계;)' and it wes designed by three height size of 0.25 ja, 0.27 ja and 0.30 ja, (4) It is estimated that the section plan was designed by the order as follows. Firstly, the horizontal position of purlins wes decided on the basis of the intersection point of long and short rafters, and then the position and the section size of purlins and jangheyo(長舌) wes decided on the basis of the slope of roof and rafters. Secondly, going down from purlins, the members of structure composed of 'jae' and 'gyoe' was repeated. Lastly, for the purpose of linking the structure members located on the center line of adjacent purlins organically, the height of whaban(화반) was controlled.

• Structural Monitoring and Maintenance
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• v.8 no.4
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• pp.329-344
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• 2021

The use of structural control devices to minimize structural response to seismic/dynamic excitations has attracted increased attention in recent years. The use of magnetorheological (MR) dampers as a control device have captured the attention of researchers in this field due to its flexibility, adaptability, easy control, and low power requirement compared to other control devices. However, little attention has been paid to the effect of configuration and number of dampers installed in a structure on responses reduction. This study assesses the control of a five-story structure using one and two MR dampers at different stories to determine the optimal damper positions and configurations based on performance indices. This paper also addresses the fail-safe current value to be applied to the MR damper at each floor in the event of feedback or control failure. The model is mathematically simulated in SIMULINK/MATLAB environment. Linear control strategies for current at 0 A, 0.5 A, 1 A, 1.5 A, 2 A, and 2.5 A are implemented for MR dampers, and the response of the structure to these control strategies for different configurations of dampers is compared with the uncontrolled structure. Based on the performance indices, it was concluded that the dampers should be positioned starting from the ground floor, then the 2^nd floor followed by 1^st and rest of the floors sequentially. The failsafe value of current for MR dampers located in lower floors (G+1) should be kept at a higher value compared to dampers at top floors for effective passive control of multi-story structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.3
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• pp.30-37
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• 2023

The PSCB girder bridge is a closed cross-section in which the top and bottom flanges and the web are integrated, and the structural characteristics are generally different from the bridges in which the girder and the floor plate are separated, so a maintenance plan that reflects the characteristics of the PSCB girder bridge is required. As a result of analyzing damage types by collecting detailed safety diagnosis reports of highway PSCB girder bridges, most of the deterioration and damage occurring during use is concentrated on the top flange. In particular, cracks in the bridge direction on the underside of the top flange occurred in about 70 % of the PSCB girder bridges to be analyzed, and these cracks were judged to be caused by indirect loads such as heat of hydration and drying shrinkage rather than structural cracks caused by external loads. In order to improve durability and reduce maintenance costs of PSCB girder bridges in use, it is necessary to control restraint drying shrinkage cracks from the design stage. Therefore, in this paper, the cracks caused by drying shrinkage under restraint, which is the main cause of cracks under the flanges of the top part of the PSCB girder bridge, were directly calculated using the Gilbert Model, and the influencing factors such as the amount of reinforcing bars, diameter and spacing of reinforcing bars were analyzed. As a result of the analysis, it was found that the crack width caused by restraint drying shrinkage exceeded the allowable crack width of 0.2 mm for reinforcing bars with a reinforcing bar ratio of 0.01 or less based on the H16 reinforcing bar and a reinforcing bar with a diameter greater than H19 based on the reinforcing bar ratio of 0.01. Finally, based on the results of the crack width review, a method for controlling the crack width of the top flange of the PSCB girder bridge was proposed.