• Journal of Korean Society of Steel Construction
• /
• v.14 no.1
• /
• pp.87-94
• /
• 2002

In the preceding study, a series of results was presented according to factors like as attaching method of main bar, shear span to depth ratio, reinforcing method for different types of region among various factors, which could determine the properties of composite beams. Based on these results, this study was planned to investigate the structural behaviors of according to attaching method of main bar for composite beams(end-reinforced concrete(RC), center-steel concrete (SC)) varying ratio of tensile bar to steel mainly. Consequently, there were little difference according to attaching method of main bar. And as the ratio of tensile bar to steel increase, the efficiency of strength was high, but ductile capacity of beams could deteriorate. Therefore, to maximize the structural properties of composite beams, it was considered that the ratio of tensile bar to steel should be limited.

• Journal of Korean Society of Steel Construction
• /
• v.27 no.2
• /
• pp.207-217
• /
• 2015

A concentrically braced steel frame is a very efficient structural system because it requires relatively smaller amount of materials to resist lateral forces. However, primarily developed as a structural system to resist wind loads based on an assumption that the structure behaves elastically, a concentrically braced frame possibly experiences the deterioration in energy dissipation after brace buckling and the brittle failure of braces and connections when earthquake loads cause inelastic behavior. Consequently, plastic deformation is concentrated in the floor where brace buckling occurs first, which can lead to the rupture of the structure. This study suggests reinforcing H-shaped braces with non-welded cold-formed stiffeners to restrain flexure and buckling and resist tensile force and compressive force equally.

• Journal of Korean Society of Steel Construction
• /
• v.28 no.1
• /
• pp.1-12
• /
• 2016

An experimental study was conducted to evaluate the static shear strength of stirrup-reinforced cast-in anchors. The test parameters considered herein are an existence of front bearing bar and concrete crack. M36 anchor was used with an edge distance of 180mm. HD-10 bars were used for all reinforcing bars and the stirrups were placed with 100mm spacing. The shear resistance increased by 16% when the front bearing bar was installed. Meanwhile, the resistance reduced only 5% in the cracked concrete compared with the uncracked concrete. The test results showed that ACI 318 and ETAG 001 specifications could estimate the shear strength of stirrup-reinforced anchors conservatively and a rational method was proposed. A consideration on the fracture strength of stirrup-reinforced anchor is also given.

• Journal of the Korean BIBLIA Society for library and Information Science
• /
• v.31 no.3
• /
• pp.191-211
• /
• 2020

The main purpose of this research is to identify limitations and problems in access to information using reading aids devices for the visually impaired and to suggest ways to activate the use of alternative materials using reading aids devices. A survey was conducted on adults with visual impairment in order to identify the factors of limitation in using reading aids devices. The analysis resulted in six aspects of limiting factors in activating the use of reading aids devices. The approaches for activating the use of reading aids devices were proposed by dividing them into policy and operational aspects, focusing on the limiting factors derived. Policy aspects suggested developing low-cost reading aids devices, increasing awareness of the devices, and complying with Web standard guidelines for improving the applicability of the devices, while operational aspects suggested reinforcing hearing-use functions, expanding information services related to reading aids devices, and enhancing portability of the devices.

• Research in Community and Public Health Nursing
• /
• v.28 no.1
• /
• pp.23-33
• /
• 2017

Purpose: The purpose of this research is to enhance organizational competitiveness of health centers as well as private medical institutions serving as public health and medical institutions. It tries to help them to cope with the requirements from health consumers, to enhance public health nurses' job performance, Methods: After verifying the reliability of the tool, confirmatory factor analysis was used to detect a model, in which valid path coefficients exist among variables. The detected model was then selected as the subject and its validity was verified. Finally, a structural equation model was applied to verify whether the estimate was suitable for the purpose of this research. Results: As for the nursing organizational culture, the public health nurses considered relation-oriented culture the most desirable. As for the self-leadership, they considered self-compensation the most desirable. It was found that mediating effects of self-leadership was partially significant. Conclusion: To enhance job performance, it is necessary to make a transition from the organizational culture to the relation-oriented culture and it is also necessary to develop a program capable of reinforcing self-leadership. In addition, it is necessary to conduct a research to verify whether such a developed self-leadership program is influential on job performance enhancement.

• KCI Concrete Journal
• /
• v.12 no.2
• /
• pp.85-93
• /
• 2000

Potentially significant mechanical improvements in tension can be achieved by the incorporation of randomly distributed, short discrete fibers in concrete. The improvements due to the incorporation fibers significantly influence the composite stress - strain ($\sigma$-$\varepsilon$) characteristics. In general incorporating fibers in a plain concrete has relatively small effect on its precracking behavior. It, however, alters its post-cracking behavior quite significantly, resulting in greatly improved ductility, crack controls, and energy absorption capacity (or toughness). Therefore, a thorough understanding the complete tensile stress - strain ($\sigma$-$\varepsilon$) response of fiber reinforced concrete is necessary for proper analysis while using structural components made with fiber reinforced concrete. Direct tensile stress applied to a specimen is in principle the simplest configuration for determining the tensile response of concrete. However, problems associated with testing brittle materials in tension include (i) the problem related to gripping of the specimen and (ii) the problem of ensuring centric loading. Routinely, indirect tension tests for plain concrete, flexural and split-cylinder tests, have been used as simpler alternatives to direct uniaxial tension test. They are assumed to suitable for fiber reinforced concrete since typically such composites comprise 98% by volume of plain concrete. Clearly since the post-cracking characteristics are significantly influenced by the reinforcing parameters and interface characteristics, it would be fundamentally incorrect to use indirect tensile tests for determining the tensile properties of fiber reinforced concrete. The present investigation represents a systematic look at the failure and toughening mechanisms and macroscopic stress - strain ($\sigma$-$\varepsilon$) characteristics of fiber reinforced concrete in the uniaxial tension test. Results from an experimental parametric study involving used fiber quantity, type, and mechanical properties in the uniaxial tension test are presented and discussed.

• Journal of the Korea Concrete Institute
• /
• v.20 no.6
• /
• pp.785-796
• /
• 2008

Longitudinal elongation develops in reinforced concrete beams that exhibit flexural yielding during cyclic loading. The longitudinal elongation can decrease the shear strength and deformation capacity of the beams. In the present study, nonlinear truss model analysis was performed to study the elongation mechanism of reinforced concrete beams. The results showed that residual tensile plastic strain of the longitudinal reinforcing bar in the plastic hinge is the primary factor causing the member elongation, and that the shear-force transfer mechanism of diagonal concrete struts has a substantial effect on the magnitude of the elongation. Based on the analysis results, a simplified method for evaluating member elongation was developed. The proposed method was applied to test specimens with various design parameters and loading conditions.

• Journal of the Korean earth science society
• /
• v.30 no.5
• /
• pp.630-645
• /
• 2009

The tropopause fold event that took place on January 1, 1997 over mid-region on the Korean Peninsula is examined by means of a numerical simulation based on a Mesoscale Model (MM5). The purpose of this paper is to investigate the effects of moisture in reinforcing a tropopause fold linked to an explosive cyclone. Two types of simulations were carried out; 1) simulations for moist conditions in which full physical and dynamic processes are considered and 2) simulations for dry conditions in which cumulus parameterization and cloud microphysics process are excluded. The results of the moist condition simulations demonstrate that the intensity of the central pressure of the cyclone was overestimated compared with the observed values and that the location of the center and the pressure deepening rates (-17 hPa/12 hr) complied with the observed values. The potential vorticity (PV) anomaly on the isentropic surface at 305 K continued to move in a southeast direction on January 1, 1997 and thus created a single tube of tropopause fold covering the northern and the middle area of the Korean Peninsula and reaching the ground surface at 0300 UTC and 0600 UTC. The results of the dry condition simulations show that the tropopause descended to 500 and 670 hPa in 0300 and 0600 UTC, respectively at the same location for the moist condition simulation; however, there was no deep tropopause fold observed. A comparison of the simulated data between the moist and the dry conditions suggests that a deep tropopause fold should happen when there is sufficient moist in the atmosphere and significantly large PV in the lower atmosphere pulls down the upper atmosphere rather than when the tropopause descends itself due to dynamic causes. Thus, it is estimated that moisture in the atmosphere should have played a crucial role in a deep tropopause fold process.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.4
• /
• pp.39-47
• /
• 2004

The SCP(sand compaction pile) method which is a vertical reinforcing technique for soft ground using a sand compaction pile has received increasing popularity in Korea. Currently, there are different methods to evaluate the bearing capacity of the reinforced ground by the SCP method. However, a method that can consider the effect of the replacement ratio on the bearing capacity is not yet available. This study investigated the effect of the replacement ratio on the bearing capacity of the reinforced ground by the SCP method. The study involved laboratory experiments which were conducted on a centrifuge facility. Test conditions included various ranges of replacement ratios (20, 30, and 40%), centrifuged consolidation, and loading. From the results of the study, a method which can evaluate the bearing capacity of the reinforced ground was proposed and verified using the weighted average of the replacement ratio.

• Journal of the Korean GEO-environmental Society
• /
• v.21 no.11
• /
• pp.11-20
• /
• 2020

For water barrier and reinforcing grout in soft ground, the verification of durability was conducted over the initial and long-term ages under various curing conditions. The grout was made of water glass system, fast-hardening mineral (FHM) system, and acrylic polymer system. There were three types of curing conditions that were tab water curing, artificial seawater curing, and atmospheric curing. And the various tests were performed for each sample by age, uniaxial compressive strength, length change, and weight change. As artificial seawater, MgCl₂ and MgSO₄ aqueous solutions were prepared and used, respectively. As the test results, the fast-hardening mineral system and acrylic polymer system were cured stably without significant change in durability in tap water and artificial sea water, whereas water glass system showed a very rapid drop in durability under artificial sea water conditions compared to tap water. In atmospheric curing conditions, durability is lowered compared to water curing in all cases, and in particular, the weight loss in the FHM system and water glass system is about 62% and 60%, respectively, resulting in a significant decrease in durability.