• International Journal of Highway Engineering
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• v.19 no.5
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• pp.107-115
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• 2017

PURPOSES : The piezoelectric energy road analysis technology using a three-dimensional finite element method was developed to investigate pavement behaviors when piezoelectric energy harvesters and a new polyurethane surface layer were installed in field conditions. The main purpose of this study is to predict the long-term performance of the piezoelectric energy road through the proposed analytical steps. METHODS : To predict the stresses and strains of the piezoelectric energy road, the developed energy harvesters were embedded into the polyurethane surface layer (50 mm from the top surface). The typical type of triaxial dump truck loading was applied to the top of each energy harvester. In this paper, a general purpose finite element analysis program called ABAQUS was used and it was assumed that a harvester is installed in the cross section of a typical asphalt pavement structure. RESULTS : The maximum tensile stress of the polyurethane surface layer in the initial fatigue model occurred up to 0.035 MPa in the transverse direction when the truck tire load was loaded on the top of each harvester. The maximum tensile stresses were 0.025 MPa in the intermediate fatigue model and 0.013 MPa in the final fatigue model, which were 72% and 37% lower than that of the initial stage model, respectively. CONCLUSIONS : The main critical damage locations can be estimated between the base layer and the surface layer. If the crack propagates, bottom-up cracking from the base layer is the main cracking pattern where the tensile stress is higher than in other locations. It is also considered that the possibility of cracking in the top-down direction at the edge of energy harvester is more likely to occur because the material strength of the energy harvester is much higher and plays a role in the supporting points. In terms of long-term performance, all tensile stresses in the energy harvester and polyurethane layer are less than 1% of the maximum tensile strength and the possibility of fatigue damage was very low. Since the harvester is embedded in the surface layer of the polyurethane, which has higher tensile strength and toughness, it can assure a good, long-term performance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.40-48
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• 2017

RC flat plates may be governed by a serviceability as well as a strength condition, and a construction sequence and its impact on the distributions of gravity loads among slabs tied by shores are decisive factors influencing short and long term behaviors of flat plate. Over-loading and tensile cracking in early-aged slabs significantly increase the deflection of a flat plate system under construction, and a reshoring work may be helpful in reducing slab deflections by controlling the vertical distributions of loads in a multi-shored flat plate system. In this study, a effect of reshoring works on short and long term deflections of flat plate systems are analyzed. The slab construction loads with various reshoring schemes and slab design and construction conditions are defined by a simplified method, and the practical calculation of slab deflections with considering construction sequences and concrete cracking and long term effects is applied. From parametric studies, the reshoring works are verified to reduce slab deflections, and the optimized conditions for the reshoring works and slab design and constructions are discussed.

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.21-28
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• 2018

Despite a number of studies on consolidation behavior that have been carried out in the Nakdong River estuary in Busan, these are focused on the prediction of final settlement during ground improvement process, and there is almost no research on the long-term settlement occurring after that. For the practical study on the long-term settlement, the field monitored settlement data that measured over 10 years in the Busan new port facilities area were used, and the final settlement and predicted time-settlement line were constituted by hyperbolic function. As a result, the measured settlements depend on the thickness of clayey soils, and the pattern were similar to each other and good agreement with the predicted time-settlement line using hyperbolic method. Also, the settlement in the lower non-improved layer occupied 62-76% of total settlement. Information about above results would be quite helpful to understand the long-term settlement behaviors as well as the non-improved layer's settlement is more careful consideration needed at design phase.

• Research in Community and Public Health Nursing
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• v.30 no.4
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• pp.400-413
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• 2019

Purpose: The use of video-recording offers important advantages in observing and assessing the relationship between specific behaviors in health care settings. The purpose of this systematic review is to investigate and synthesize the methodological characteristics of studies using video-technology for measuring interactions with the older persons with dementia and staff in long-term care facilities. Methods: We searched Medline, Embase and CINHAL databases for published articles in English using a video-recording method for both staff and the residents with dementia. Quantitative research design studies (e.g., descriptive or experimental studies) were included. Results: Among 5,605 searched papers, a total of 20 studies were selected for this review. Situations of video-recording were providing personal care (n=12), mealtime (n=6), and conversation (n=3). Concepts measured by video-recording were classified into two groups: 1) Staff [care practice by staff (n=13) and communication by staff (n=11)] and 2) residents [communication by resident (n=4), activities of daily life function of resident (n=8), and behavioral and psychological symptoms of dementia (n=10)]. Conclusion: This review demonstrates that video technologies are actively used to evaluate the relationship between quality of care and health outcomes of the elderly with dementia in many international nursing studies. This study provides the foundation for a future research using video-recording technologies to examine the interactions and relationships between staff and the residents in Korean long-term care settings.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.245-248
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• 2008

Concrete structures show time-dependent behavior due to creep and shrinkage of concrete and the uncertainties of creep and shrinkage are very huge. To reduce uncertainties of creep and shrinkage, it is substantially necessary to perform the long-term creep and shrinkage tests, but actual construction process doesn't allow it due to the limited time. Even though the tests are performed in laboratory, the values obtained from the tests could be different from the actual values in construction site because of the different environment between the laboratory and construction site and the model uncertainty itself. It is difficult to predict the long-term behaviors of concrete structures properly if the assumed creep coefficient obtained from Codes or the results of experiments is different from the real characteristics of concrete creep. In this study, for predicting the long-term behavior, the creep coefficients in reinforced concrete beams are estimated using creep sensitivity analysis from the measured deflections with time. And estimated creep coefficients using creep models of ACI Committee 209 and CEB-FIP MC90 are compared.

• The Journal of Korean Physical Therapy
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• v.25 no.1
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• pp.36-41
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• 2013

Purpose: To investigate whether the long-term use of a cane induces pain in the unaffected lower limb of stroke patients. Methods: A total of 107 stroke patients with chronic hemiparesis were recruited in this study and classified into two groups; a cane-use group (n=49) and non-cane-use group (n=58). The existence of pain in the unaffected lower limb was assessed on a visual analog scale in the hip, knee, and ankle joint, and the University of Alabama pain behaviors scale (UAB pain behavior scale) used to measure the intensity of pain. In addition, the Motricity Index (MI) was tested in the upper and lower extremities. Results: The proportion of pain in each joint of the lower limb was significantly higher in the cane-use group, compared to the non-cane-use group (p<0.05). In addition, significant differences were observed on the UAB pain behavior scale between the two groups. The lower MI score was significantly lower in the cane-use group, compared with the control group. However, no difference was observed in MI scores of the upper limb between the two groups. Conclusion: These findings reveal that long-term cane usage can induce pain in the unaffected lower limb of stroke patients. We suggest careful consideration when prescribing a cane, depending on functional ability in hemiparetic patients, and recommend continuous evaluation for pain in the affected lower limb.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.2
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• pp.119-129
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• 2022

It is essential to control the lateral displacement and differential axial shortening of the vertical elements in high-rise buildings. The differential axial shortening can cause challenges in the serviceability and safety of non-structural and structural elements, respectively. Hence, in this study, the differential axial shortening of the vertical elements and effects of long term behaviors of concrete are analyzed in 120-story high-rise buildings via the construction sequence analysis. Consequently, the axial shortening of the vertical elements is classified into elastic, creep, and shrinkage shortening, and dominant factors to the maximum axial shortening are analyzed. In addition, the serviceability of the non -structural elements is checked with a differential axial shortening at 30 years after completion of construction, and member forces at design and construction stages in girders and outrigger walls are compared.

• Journal of the Korean Geotechnical Society
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• v.24 no.7
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• pp.37-42
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• 2008

This paper estimates the long-term settlement of Incheon unsanitary solid waste landfill, which is 20 years old. The unsanitary solid waste landfill was subjected to pre-loading system over a period of 1 year, and 300 settlement monitoring provided the long term settlement data. This landfill contains relatively small amount of organic component, and therefore the initial stage of settlement was very small. The existing settlement models were examineed by comparing the observed behaviors of this site, and also they were used to predict the long-term settlement. Power Creep Law (PCL) model showed good agreement with the measured settlement obtained from the initial stage of the measurement, but other models showed satisfactory agreements after $50{\sim}70$ days of measurement.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.9
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• pp.51-61
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• 2020

This research investigates the consequences of the increase in corporate use of short-term debt in China over the past decades. Using a sample of Chinese firms from 2007 to 2018, we empirically explore the effect of corporate use of short-term debt for long-term investment (SFLI) on audit pricing. We first examine the relationship between SFLI and audit pricing for different groups of firms. Then, we investigate the role of the increase in short-term debt in alleviating principal-agent conflicts and reducing agency costs. We have four primary empirical findings. First, auditors tend to charge SFLI clients higher fees. Second, the negative relationship between SFLI and audit fee is found in private firms, firms audited by Chinese domestic auditors, and firms with higher information asymmetry. Third, the time auditors spent on SFLI clients is significantly more than that spent on non-SFLI clients, suggesting that the decrease in audit fee is not due to the decrease in cost. Fourth, SFLI significantly reduces the agency costs of the firm, which auditors regard as a low risk signal and grant an audit fee discount. Our findings suggest that the decrease in debt maturity, not only influences managerial behaviors, but also influences auditors' risk assessment and pricing decisions.

• Journal of Ocean Engineering and Technology
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• v.33 no.6
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• pp.632-640
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• 2019

Desalination plant ships have been recently regarded as one of the probable solutions for drought seasons in many countries. Because desalination plants should be mounted on the desalination ships and special purpose storages such as salty waste water tanks are necessary, onboard and compartment arrangements would be distinguished from those of other conventional commercial ships. This paper introduces some basic design procedure including resistance/propulsion and seakeeping performances. The ship lines were improved step by step after modification of the ship lines and verification of resistance/propulsion performances using computational fluid dynamics (CFD). After finalization of the ship lines, the seakeeping performance was also evaluated to check motion behaviors and drive wave-induced loads such as the wave shear force and bending moment. It was proved that the predicted long-term vertical wave shear force and bending moment were significantly less than the rule-based ones, thus it is expected that the deliverables of this study will reduce the construction cost of desalination plant ships.