• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.114-120
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• 2017

In this paper, the effect of the masonry infill walls on the seismic performance of the reinforced concrete(RC) frames with non-seismic details was evaluated through the static test of an masonry infilled RC frame sub-assemblage with non-seismic details of real size, and comparison with the test results of the RC frame sub-assemblage with non-seismic details. As the test results, lots of cracks occurred on the surface of the entire frame due to the compression of the masonry infilled wall, and the beam-column joint finally collapsed with the expansion of the shear crack and buckling(exposure) of the reinforcement. On the other hand, the stiffness of the shear force-story drift relationship decreased due to the wall sliding crack and column flexural cracks, and the strength finally decreased by around 60% of the maximum strength. The damage that concentrated on the upper and lower parts of columns was dispersed in the entire frame such as columns, a beam, and beam-column joints due to the wall, and the specimen was finally collapsed by expansion of the shear crack of the joint, not the shear crack of the column. Also, the stiffness of RC frame increased by 12.42 times and the yield strength by 3.63 times, while the story drift at maximum strength decreased by 0.18 times.

• Journal of Korean Academy of Nursing
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• v.28 no.1
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• pp.70-80
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• 1998

This study is designed to contribute to the nursing intervention of adolescent domestic violence victims by describing specifically what they go through and on this basis work out a grounded theory on the adolescent's experience in domestic violence. The data were analyzed in the framework of grounded theory as mapped out by Strauss & Corbin(1990). The major findings of this research are as follows : The core category was found to be the the adaptation of "Joyudeum" or “Straight jacketing”. The sub-categories identified in the process of grounded data analysis were 'menacing', 'being harassed', 'being pressed', 'being attacked', 'being strapped', 'being filled with anger'. 'getting angry', 'being oppressed', 'being strained', 'becoming hard', 'endurance', 'regulation', 'seriousness'. 'repitition'. 'being helpful', 'dependence', 'thinking oriented', 'blowing off', 'going astray', 'self-deprecating', 'shaking off', 'covering up', 'governing', 'being devoted', 'performing', 'being transformed'. 'bolting', 'being shaken', 'withdrawing', 'disliking', 'bitterness'. These categories were again grouped into 13 categories including 'threatening'. 'straight jacketing', 'tolerance', 'violence', 'supporter', 'supporting type', 'thinking oriented'. 'impulsive response', 'self-controlled', 'response', 'self-reliance', 'wandering', 'withdrawal' and pain'. Of these the five sub-categories 'being filled with anger'. 'getting angry', 'being oppressed', 'being strained', 'becoming hard' were grouped into a core category "straight jacketing". Those adolescents brought up in a violent family go through three stages of the adaptation of "straight Jacketing". that is, generation, response and adaptation. The following four theses were confirmed on the basis of repetitive relations : 1) If a subject's tolerance is strong, the episodes of the violence are frequent and serious, with the resulting straight jacketing being stronger but the subject's supporter is highly mature, the supporting type is concrete and the thinking oriented is wishful, the responses to the straight jacketing result in a self-control whose consequence is self-reliance with part of it resulted in withdrawal and pain. 2) If a subject's tolerance is weak, the episodes of the violence are frequent but not serious, with the resulting straight jacketing being weaker but the subject's supporter is immature, the supporting type is superficial and the thinking oriented is extemporary, the responses to the straight jacketing result in an impulsion whose consequence is wandering with part of it resulted in withdrawal and pain. 3) If a subject's tolerance is weak, the episodes of the violence are frequent and serious, the straight jacketing is strong, the subject's supporter is immature and the supporting type is superficial but the thinking oriented is wishful, the responses to the straight jacketing result in an impulsion whose consequence is withdrawal and pain with part of it resulted in wandering. 4) If a subject's tolerance is strong and the episodes of the violence are infrequent and not serious, the straight jacketing is weak, the subject's supporter is immature and the supporting type is superficial but the thinking oriented is wishful, the responses to the straight jacketing result in a self-control whose consequence is withdrawal and pain with part of it resulted in self-reliance.

• Journal of the Korea Concrete Institute
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• v.15 no.1
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• pp.102-109
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• 2003

The grouted splice steeve has been applied widely due to its superior construction efficiency, such as the unnecessity of post concrete and the large allowable limit to the arrangement of reinforcing bars. However, studies on grout-filled splice steeve still have not been sufficiently peformed. The purpose of this study is to investigate the confining effect of mortar grouted splice sleeve on reinforcing bar, known to strengthen the bond capacity between grout mortar and reinforcing bar. To accomplish this objective, totally 6 full-sized specimens were made and tested under monotonic loading. Each specimens were equipped with strain gauges at the 12 location of sleeve and reinforcing bar. The experimental variables adopted in this study are embedment length and size of reinforcing bars. Following conclusions are obtained; 1) Under ultimate strength condition, the confining pressure of grouted splice sleeve calculated from measured tangential and axial strain of the sleeve is over $200{\sim}300kgf/{cm}^2$ at any location of sleeve and improved with reduction in embedment length of reinforcing bar. 2) Untrauer and Henry's equation which describe bond strength of mortar as a function of its compressive strength and confining pressure, predicted the measured bond capacity of this test within the 5% limits.

• Journal of the Korean Geotechnical Society
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• v.32 no.8
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• pp.5-14
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• 2016

The leakage of water under sewer pipelines is one of main sources of sinkholes in urban areas. We performed laboratory model tests to investigate the presence of cavities using impact-echo method, which is a nondestructive test method. To simulate a concrete sewer pipe, a thin concrete plate was built and placed over container filled with sand. The cavity was modeled as an extruded polystyrene foam box. Two sets of tests were performed, one over sand and the other on cavity. A new impact device was developed to apply a consistent high frequency impact load on the concrete plate, thereby increasing the reliability of the test procedure. The frequency and transient characteristics of the measured reflected waveforms were analyzed via fast Fourier transform and short time Fourier spectrum. It was shown that the shapes of Fourier spectra are very similar to one another, and therefore cannot be used to predict the presence of cavity. A new index, termed resonance duration, is defined to record the time of vibration exceeding a prescribed intensity. The results showed that the resonance duration is a more effective parameter for predicting the presence of a cavity. A value of the resonance period was proposed to estimate the presence of cavity. Further studies using various soil types and field tests are warranted to validate the proposed approach.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1377-1387
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• 2013

Most embankment of the reservoirs (99.1 %) have been constructed in the earth filled type in Korea because the construction of this type is less expensive and simpler than others such as concrete one. However, it has to be reinforced the slope to prevent the breach due to overtopping or piping under unexpected flood conditions. This study has been analyzed the retardation effect using three types (L, T, $L^*$ shape) of stiffener in order to reinforce embankment when they are collapsed by overtopping flow. Experimental results showed that L-type stiffener is the most effective in delaying the breaching of embankment and reducing the soil erosion when compared with others. The reinforced embankment breaching showed that time delay was occurred about 1.73 to 2.29 times and the peak flowrate was reduced compared to non-stiffener embankments due to energy dissipation by collision and less soil erosion. The embankment breaching mostly leads to major damages because of the lack of repair time. Thus, since these stiffeners can resist the rapid breach, it would be possible to earn the time to emergency repair and lifesaving, as well as reduction of damages of embankment in downward region with decreasing peak flowrate. Results from this study would be used for the basis when establishing the emergency action plan for the reservoirs on the verge of hazard.

• Journal of the Korean Institute of Rural Architecture
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• v.18 no.1
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• pp.57-65
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• 2016

When the castle of the city was destructed from 1911 through 1915 in Cheongju, the city's spatial structure was reorganized and "Han-ok Housing", a dwelling site filled with Korean traditional houses, was newly formed around the former castle site. These days, the Han-ok housing in Seoun-dong, Cheongju in which elderly couples and senior citizens live is enclosed by modernized roads and three or four-story buildings, leaving the housing as an isolated island in the city block. Nonetheless, the Han-ok housing not only plays an important role in sustaining the historic and local identity of the city, but also offers environmental benefits in terms of daylighting and ventilation. The purpose of this study is to reorganize the housing suitable for those who currently live and recreate it by adding new functionality. Consequently, three strategies are established; the conservation of existing building through the improvement of existing facilities; the conversion of vacant buildings into a new use; and the creation of the urban mid-rise Han-ok housing at street sides. The first strategy has a significance in that the traditional building's single wing plan, small room sizes and lack of storages now cause great inconvenience for current life style. The second strategy also promotes the practical use of abandoned buildings through alterations and additions. Finally, the creation of the urban mid-rise Han-ok housing that is accomplished by the combination of reinforced concrete and wooden structure interacts with or respond to the city's development. As a result, this study for the adaptive reuse of Han-ok housing proves how the traditional properties can be maintained in a careful manner and how its creative reuse can be achieved.

• Steel and Composite Structures
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• v.22 no.5
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• pp.1085-1114
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• 2016

This paper investigates the transverse impact response for ultra lightweight cement composite (ULCC) filled pipe-in-pipe structures through a parametric study using both a validated finite element procedure and a validated theoretical model. The parametric study explores the effect of the impact loading conditions (including the impact velocity and the indenter shape), the geometric properties (including the pipe length and the dimensions of the three material layers) as well as the material properties (including the material properties of the steel pipes and the filler materials) on the impact response of the pipe-in-pipe composite structures. The global impact responses predicted by the FE procedure and by the theoretical model agree with each other closely. The parametric study using the theoretical approach indicates the close relationships among the global impact responses (including the maximum impact force and the maximum global displacement) in specimens with the equivalent thicknesses, proposed in the theoretical model, for the pipe-in-pipe composite structures. In the pipe-in-pipe composite structure, the inner steel pipe, together with the outer steel pipe, imposes a strong confinement on the infilled cement composite and enhances significantly the composite action, leading to improved impact resistance, small global and local deformations.

• Structural Engineering and Mechanics
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• v.43 no.5
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• pp.607-621
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• 2012

The Expo Culture Centre is one of the permanent buildings at the World Expo 2010 in Shanghai, China. The main structure has an oval shape and consists of 36 radial cantilever steel trusses with different lengths and inner frames made of concrete-filled rectangular steel tube members. Tuned mass dampers are used to reduce the excessive vibrations of the sixth floor that are caused by human-induced resonance. A three-dimensional analytical model of the system is developed, and its main characteristics are established. A series of field tests are performed on the structure, and the test results show that the vertical vibration frequencies of most structural cantilevers are between 2.5 Hz and 3.5 Hz, which falls in the range of human-induced vibration. Twelve pairs of tuned mass dampers weighing 115 tons total were installed in the structure to suppress the vibration response of the system. These mass dampers were tuned to the vertical vibration frequency of the structure, which had the highest possibility of excitation. Test data obtained after the installation of the tuned mass dampers are used to evaluate their effectiveness for the reduction of the vibration acceleration. An analytical model of the structure is calibrated according to the measured dynamic characteristics. An analysis of the modified model is performed and the results show that when people walk normally, the structural vibration was low and the tuned mass dampers have no effect, but when people run at the structural vibration frequency, the tuned mass dampers can reduce the floor vibration acceleration by approximately 15%.

• Journal of the Korea Institute of Building Construction
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• v.24 no.1
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• pp.23-34
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• 2024

This research aims to assess the flexural bonding efficacy of polymer-cement composites(PCCs) in mending cracks within reinforced concrete(RC) structures. The study involved infilling PCCs into cement mortar cracks of varying dimensions, followed by evaluations of enhancements in flexural adhesion and strength. The findings indicate that the flexural bond performance of PCCs in crack repair is influenced by the cement type, polymer dispersion, and the polymer-to-binder ratio. Specifically, the use of ultra-high early strength cement combined with silica fume resulted in an up to 19.0% improvement in flexural bond strength compared to the application of ordinary Portland cement with silica fume. It was observed that the augmentation in flexural strength of cement mortar filled with PCCs was significantly more dependent on the depth of the crack rather than the width. Furthermore, PCCs not only acted as repair agents but also as reinforcement materials, enhancing the flexural strength to a certain extent. Consequently, this study concludes that PCCs formulated with ultra-high early strength cement, various polymer dispersions, silica fume, and a high polymer-to-binder ratio ranging from 60% to 80% are highly effective as maintenance materials for crack filling in practical settings.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.2
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• pp.69-77
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• 2017

By producing pre-engineered modular system in the factory, It is enable to expedite construction and can be distinguished from two types by the method resisting load. One is the open-sided modular system composed of beams and columns. The other is enclosed modular system composed of panels and studs. Of the modular systems, the open-sided modular system buildings the connection between modules are difficult due to closed member sections, and the overall strength is reduced as a result of local buckling. In this study, in order to solve these problems, a modular system with folded steel members filled with concrete are proposed. The capacity spectrum method presented in ATC 40 is used for seismic performance assessment of the proposed model structure and the structure with conventional steel members. The analysis results show that at the performance point of each model the number and rotation of plastic hinge formed in the proposed modular system are smaller than those in the conventional system. Based on this observation it is concluded that the proposed system with composite sections has superior seismic capacity compared with conventional system.