• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.267-273
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• 2020

Suction anchors are used for floating structures because they have advantages in installation and stability. Recently, the demand for floating structures requiring low allowable displacement has increased. Thus, it is strongly suggested that the displacement of the suction anchor be evaluated. However, conventional studies regarding suction anchors have concentrated on the capacity of the anchor, and research on the displacement of the anchor is limited. In particular, rotation is the primary behavior of a suction anchor subjected to an inclined load, and related information has been insufficient. Therefore, the main objective of this paper is to investigate the rotation behavior of a suction anchor via centrifuge model tests. The experimental parameters are the inclination of the pull-out load, anchor dimensions, and aspect ratio. The rotation values of suction anchors were compared using a series of load-rotation curves. The results show that the inclination of the load has a dominant influence on the rotation behavior of the suction anchor.

• Geomechanics and Engineering
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• v.12 no.2
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• pp.295-312
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• 2017

Cast in situ and grouted concrete helical piles with 150-200 mm diameter half cylindrical ribs have become an economical and effective choice in Shanghai, China for uplift piles in deep soft soils. Though this type of pile has been successful used in practice, the reinforcing mechanism and the contribution of the ribs to the total resistance is not clear, and there is no clear guideline for the design of such piles. To study the inclusion of ribs to the contribution of shear resistance, the shear behaviour between silty sand and concrete slabs with parallel ribs at different spacing and angles were tested in a large direct shear box ($600mm{\times}400mm{\times}200mm$). The front panels of the shear box are detachable to observe the soil deformation after the test. The tests were modelled with three-dimensional finite element method in ABAQUS. It was found that, passive zones can be developed ahead of the ribs to form undulated failure surfaces. The shear resistance and failure mode are affected by the ratio of rib spacing to rib diameter. Based on the shape and continuity of the failure zones at the interface, the failure modes at the interface can be classified as "punching", "local" or "general" shear failure respectively. With the inclusion of the ribs, the pull out resistance can increase up to 17%. The optimum rib spacing to rib diameter ratio was found to be around 7 based on the observed experimental results and the numerical modelling.

• Journal of Oriental Neuropsychiatry
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• v.30 no.3
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• pp.185-198
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• 2019

Objectives: The purpose of this study was to identify the effectiveness of Korean medicine treatment in mild cognitive impairment (MCI) among a group of community dwelling elderly. Methods: Two-hundred and twenty-nine elderly living in a community and diagnosed with MCI were recruited. Participants were evaluated with various instruments such as the Korean version of Mini-Mental State Examination for Dementia Screening (MMSE-DS) and the Korean version of Montreal Cognitive Assessment (MoCA-K). Korean medicine treatment consisted of herbal medicine, acupuncture, and pharmacoacupuncture. The change in cognitive ability was assessed by using the MMSE-DS and the MoCA-K. Data were analyzed by SPSS/WIN 22.0 using the paired t-test, and the ANOVA. Results: The MMSE-DS and the MoCA-K score generally increased after six months of Korean medicine treatment and the differences in both instruments were statistically significant. Additionally, some consecutive participants maintained long-term cognitive improvement. When analyzed specifically by herbal medicine group based on syndrome differentiation and pharmacoacupuncture group, most showed improvement in the MMSE-DS and the MoCA-K but not all data were statistically significant. The satisfaction score was mostly high and most participants were willing to re-participate in the program. Conclusions: Korean medicine treatment may contribute to the improvement and prevention of cognitive decline in the elderly. However, further systematic research based on large scale sample data and standardized protocols is needed to uplift the welfare and mental health of the elderly.

• The Journal of the Korea Contents Association
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• v.22 no.10
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• pp.546-553
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• 2022

This research has focused on identifying a significant cause of the pavement cracks and irregularities of roads in Changwon city which have been constructed using steel slag, an auxiliary-based material. It is important to note that the cracks and irregularities yield logistics inconvenience, the risk of traffic accidents, and increased road maintenance costs. X-ray diffraction analysis tests have been conducted in this study on the sample collected by pavement cutting and excavating the three target roads. It is well known that the primary cause of the expansion of steelmaking slag is the hydration reaction between CaO and MaO. While the reaction of CaO is completed within a few months, that of MgO is pretty slow depending on the firing temperature. The test results reveal that the MgO content of the testing samples is approximately 47% of the total average, and that of CaO is around 14% of the total average. Hence, these results make it possible to be understood that the expansion induced by the slow hydration reaction of MgO results in road uplift in the long term, resulting in the cracks and irregularities of roads.

• Steel and Composite Structures
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• v.45 no.6
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• pp.797-818
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• 2022

Steel-precast ultra-high-performance concrete (UHPC) composite beams with demountable high-strength friction-grip bolt (HSFGB) shear connectors can be used for accelerated bridge construction (ABC) and achieve excellent structural performance, which is expected to be dismantled and recycled at the end of the service life. However, no investigation focuses on the demountability and reusability of such composite beams, as well as the installation difficulties during construction. To address this issue, this study conducted twelve push-out tests to investigate the effects of assembly condition, bolt grade, bolt-hole clearance, infilling grout and pretension on the crack pattern, failure mode, load-slip/uplift relationship, and the structural performance in terms of ultimate shear strength, friction resistance, shear stiffness and slip capacity. The experimental results demonstrated that the presented composite beams exhibited favorable demountability and reusability, in which no significant reduction in strength (less than 3%) and stiffness (less than 5%), but a slight improvement in ductility was observed for the reassembled specimens. Employing oversized preformed holes could ease the fabrication and installation process, yet led to a considerable degradation in both strength and stiffness. With filling the oversized holes with grout, an effective enhancement of the strength and stiffness can be achieved, while causing a difficulty in the demounting of shear connectors. On the basis of the experimental results, more accurate formulations, which considered the effect of bolt-hole clearance, were proposed to predict the shear strength as well as the load-slip relationship of HSFGBs in steel-precast UHPC composite beams.

• Journal of the Korean GEO-environmental Society
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• v.13 no.11
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• pp.61-68
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• 2012

Most widely methods for reinforcement of soil utilized in Korea are anchor method, soil nail method and micro pile method. These methods are classified by the intended use of the structure to be constructed, but the reinforcement of the ground is accomplished contains in common the process of grouting work after inserting the reinforcements. Domestically, gravity grouting has been used mostly so far, but there has always been the risk of insufficient restoration of the loose ground area from the drill holes because the grouting is conducted only by gravity. On the other hand, pressure reinjection grouting may enhance the grouting quality by solving the problem of the existing grouting method considerably since it additionally reinjects grouting through pre-installed tube a certain time after the first grouting. Accordingly, this study evaluated the pullout characteristics by the grouting methods by performing model test on decomposed granite soil, and investigated the support increasing characteristics of reinforcements depending on the curing time, reinjection pressure, and uplift force variation of the pressure reinjection grouting. The result of this research shows that the pressure reinjection grouting demonstrated 1.1~1.3 times of performance of the gravity grouting, and suggests some analysis on optimal water content, reinjection pressure and curing time of the pressure reinjection grouting.

• Journal of the Korean GEO-environmental Society
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• v.16 no.10
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• pp.15-22
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• 2015

In this study, to evaluate the long-term behavior characteristics and the loss of prestress force, the long-term measurement of the tensile anchors in the actual construction was performed and the results were analyzed comparing with the existing estimation. As the reinforcement member used for the purpose of slope stability or uplift-resisting of the permanent structure, etc, the permanent anchor should maintain the functions during the performance period of the structure differently from the temporary anchor. However, as the time passes by, since the relaxation and the creep of the anchor occur constantly, the management for the loss of tensile force is essential to perform the functions stably. So far, the loss of the tensile force has been estimated according to the reduction of the prestress using elasticity theory and using the relaxation value according to the type of tension member and the test using the long-term measurement is limited. Therefore, in this study, the site condition and the ground were investigated for the tensile anchor in the actual construction and the long-term measurement results more than 500 days was analyzed by installing the loadcell, inclinometer and the groundwater level gauge. In addition, the long-term behavior characteristics were evaluated by comparing the disposition of the measured earth retaining wall and the tension force loss of the anchor with the existing interpretation results. In the evaluation results, the most of the tension force loss occurs within 90 days and the loss was measured less than the estimated values.

• Journal of Distribution Science
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• v.13 no.4
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• pp.89-98
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• 2015

Purpose - In today's globalized and modern business environment, corporate social responsibility (CSR) activities are considered to be essential for the sustainable development of enterprises. In addition, the corporate philanthropy that is related to CSR practices, as well as their being capable of reducing the anti-corporate sentiment of people have facilitated a qualitative forward leap into the quantitative growth phase. This study aims to undertake a comparative evaluation of corporate philanthropy through the Importance-Performance Analysis (IPA) method focusing on service and manufacturing industries, and to eventually determine a differentiated approach that is needed for corporate philanthropy. Research design, data, and methodology - The survey responses were collected through online research on specialized companies from consumers nationwide who were aged from 20 to 60 and who are aware of corporate philanthropy. A total of 408 sheets of questionnaire survey were used. Frequency analysis was undertaken in this study. The interviewees had demographic characteristics of gender: 206 males (50.5%) and 202 females (49.5%). They also had demographic characteristics of age: 82 people were over 20 (20.1%), 96 over 30 (23.5%), 105 over 40 (25.7%), and 125 over 50 (30.7%) years of age. The distribution of interviewees' residences is as follows: 154 persons (37.7%) in the Special City, 102 persons (25.0%) in the Metropolitan City, and 152 persons (37.3%) in the Provincial Region. The interviewees have been working for the following companies: 34 persons (8.3%) in LG Display, 80 (19.6%) in KT&G, 49 (12.0%) in Amore Pacific, 42 (10.3%) in KIA Motors, 47 (11.5%) in SBS, 52 (12.8%) in Shinhan Bank, 86 (21.1%) in Asiana Airlines, and 18 (4.4%) in Hyundai Department Store. We applied the paired t-test for the IPA analysis. PASW Statistics 18 was used for statistical analysis. Results - The results of IPA analysis indicated that the importance and performance degrees in both manufacturing and service industries were significantly different. Major empirical results showed that, in consumer, social, economic, philanthropic, and environmental dimensions, in the sub-factors of philanthropy activities in both manufacturing and service industries, the importance degree was found to be higher than performance degree. Further, the average difference between importance degree and performance degree by the sub-factors of philanthropy activities. On the other hand, the average difference of environmental dimension was found to be highest in both service and manufacturing industries. Thus, while consumers consider the philanthropy activities of the environmental dimension as most important, actual companies treat performance of philanthropy activities of the environmental dimension insufficiently or negligibly to some degree. Conclusions - The differentiated approach method that is required for corporate philanthropy may be proposed to uplift corporate accomplishments by analyzing the IPA of the attributes of the sub-factors of corporate philanthropy. This is, to an extent, insufficient in the existing studies related to the use of the IPA technique, and it shows the items that are to be conducted intensively.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.65-74
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• 2003

Most of land reclamation projects are being implemented along the south and west coastal lines of the Korean Peninsula. The earth structures and in-ground LNG tank, and buildings can be constructed using artificial freezing method on the reclaimed land to control the uplift pressure caused by capillary forces. In this study, upon freezing a saturated soil in a closed-system from the top, a considerable frost heaving pressure was developed. Decomposed granite soils, silty soil, and sandy soil were used in the laboratory freeze test which is sometimes subjected to thermal gradients under closed-systems. A major concern has been the ability to predict the frost heaving pressure over the results of relatively short-term laboratory tests. The frost heaving pressure arising within the soil samples and the temperature of the samples inside were monitored with time elapse. The degree of saturation versus heaving pressure curve is presented for each soil sample and the maximum pressure is closely related to this curve. TDR apparatus was used to measure the volumetric water content by the measurement of unfrozen water contents of frozen soils. Unfrozen water increased in soils containing a high percentage of fine-grained particles. In fine-grained soils with strong attractive farces between soil grains and water molecules, additional water is attracted into the pores leading to further volume changes and ice segregation.