• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.2
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• pp.69-76
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• 2024

The rheological properties of fresh concrete significantly influence its manufacturing and performance. However, the diversification of newly developed mixtures and manufacturing techniques has made it challenging to accurately predict these properties using traditional empirical methods. This study introduces a multiscale rheological property prediction model designed to quantitatively anticipate the rheological characteristics from nano-scale interparticle interactions, such as those among cement particles, to micro-scale behaviors, such as those involving fine aggregates. The Yield Stress Model (YODEL), the Chateau-Ovarlez-Trung equation, and the Krieger-Dougherty equation were utilized to predict the yield stress for cement paste and mortar, as well as the plastic viscosity. Initially, predictions were made for the paste scale, using the water-cement ratio (W/C) of the cement paste. These predictions then served as a basis for further forecasting of the rheological properties at the mortar scale, incorporating the same W/C and adding the cement-sand volume ratio (C/S). Lastly, the practicality of the predictive model was assessed by comparing the forecasted outcomes to experimental results obtained from rotational rheometer.

• Journal of Distribution Science
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• v.14 no.5
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• pp.115-123
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• 2016

Purpose - Nowadays the competition between companies has been intensified in the aviation industry. It is hard to maintain successful market share in challenging managerial environment. Not long ago, a Korean major aviation company had faced social condemnation cause of managerial staff's immoral behaviors. That company suffers great losses in company brand value in terms of authenticity as an aviation company. This research tried to show the effect of brand authenticity in the aviation industry. First of all, this research tried to define the dimensions of the brand authenticities based on the former researches. This research suggested the airline brand authenticities as three kinds of dimensions. The dimensions of authenticities consist of performance aspects, symbolic aspects and moral aspects. And this research also tried to show the relationships between brand authenticities and consumers attitudes. Research design, data and methodology - The empirical research design is based on the experiments with six types of advertisement prototypes. The advertisement prototypes were based on three types of authenticities' characteristics. The prototypes were made of core statements about each authenticity. And the advertisement prototypes also were based on the aviation company types. The types of aviation companies could be divided into FSC(full service carrier)and LCC(low cost carrier). So the whole experiments were performed with six kinds of advertisement prototypes(3 brand authenticities X 2 aviation company types). The age of participants were from 20s to 40s. The proportion of participants' demographics are as follow. Age proportion is 50% of 20s and 50% of 30s and 40s. Gender proportion is 46% males and 54% females. The experiments performed through mobile devices. Advertisement prototypes were exposed to the participants through their mobile devices, and they answered the questionnaires. All the process of experiments were performed by a professional research firm to maintain the quality of data. Results - This research suggested some important outcomes as follow. First, brand authenticity had an important role to make a positive consumer attitude on the aviation company. All the three types advertisement of authenticities had a positive impact on the consumer attitude for the aviation company. Second, the three types of brand authenticities in the performance aspects, symbolic aspects, and moral aspects had a major impact on the consumers attitudes. The performance authenticity had the biggest effect on the consumer attitudes. Third, the types of aviation companies like FSC and LCC had a different correlation with types of authenticities. All the types of authenticities affected on the consumers attitudes in the FSC case. The symbolic authenticity had the biggest effect in the FSC case. But the performance authenticity showed the most striking effect in the LCC case. Conclusion - From this research, we can get a conclusion. The brand authenticity of aviation company should be managed carefully to maintain a positive brand image and consumers attitudes. And airline brand authenticities can be consist of three type dimensions. All the types of authenticities affects on the consumers attitudes positively. The symbolic authenticity affects more in the FSC case, and the performance authenticity influences more in the LCC case.

• Journal of the Korean Geotechnical Society
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• v.28 no.8
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• pp.21-29
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• 2012

At-rest lateral stress coefficient that is used for the evaluation of geotechnical structures such as foundations and retaining walls plays a significant role in the analysis and design, as a state variable of in-situ stress condition. In the widely applied Jaky's Ko equation stress condition can be inferred from the internal friction angle obtainable from the laboratory experimentation whereas the eguation mares it challenging to evaluate the influences and criteria of particle characteristics which is essential for the application of friction angles in practices. Thus, this study experimentally explored the behaviors of Ko depending on the relative density, particle shape, and surface roughness effect during a range of loading stages. The Ko values of Jumumjin sand, glass beads, and etched glass beads were measured using a customized Ko device housing strain gauges during loading-unloading-reloading steps, and the effect of dominant factors on Ko is analyzed. Results show that the high Ko prevails for both round and angular specimens with low relative density and the surface roughness has a nominal effect. The angular particles exhibit low Ko for specimens with similar relative density. The characteristics of relevance between Ko and friction angles with varying relative density are also investigated based on the experimental results using empirical correlations and previously reported values.

• Korean Journal of Construction Engineering and Management
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• v.19 no.1
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• pp.21-31
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• 2018

The rapid increase of the elderly living alone is a critical issue in worldwide as it leads to a rapid increase of a social support costs (e.g., medical expenses) for the elderly. In early stages of dementia, the activities of daily living (ADL) including self-care tasks can be affected by abnormal patterns or behaviors and used as an evidence for the early diagnosis. However, extracting activities using non-intrusive approach is still quite challenging and the existing methods are not fully visualized to understand the behavior pattern or routine. To address these issues, this research suggests a model to extract the activities from coarse-grained data (spatio-temporal data log) and visualize the behavioral context information. Our approach shows the process of extracting and visualizing the subject's spaceactivity map presenting the context of each activity (time, room, duration, sequence, frequency). This research contributes to show a possibility of detecting subject's activities and behavioral patterns using coarse-grained data (limited to spatio-temporal information) with little infringement of personal privacy.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.3
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• pp.91-99
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• 2024

Piping systems are crucial facilities used in various industries, particularly in areas related to daily life and safety. Piping systems are fixed to the main structures of buildings and facilities but do not support external loads and serve as non-structural elements performing specific functions. Piping systems are affected by relative displacements owing to phase differences arising from different behaviors between two support points under seismic loads; this can cause damage owing to the displacement-dominant cyclic behavior. Fittings and joints in piping systems are representative elements that are vulnerable to seismic loads. To evaluate the seismic performance and limit states of fittings and joints in piping systems, a high-stroke actuator is required to simulate relative displacements. However, this is challenging because only few facilities can conduct these experiments. Therefore, element-level experiments are required to evaluate the seismic performance and limit states of piping systems connected by fittings and joints. This study proposed a method to evaluate the seismic performance of an elbow specimen that includes fittings and joints that are vulnerable to seismic loads in vertical piping systems. The elbow specimen was created by connecting straight pipes to both ends of a 90° pipe elbow using flexible groove joints. The seismic performance of the elbow specimen was evaluated using a cyclic loading protocol based on deformation angles. To determine the margin of the evaluated seismic performance, the limit states were assessed by applying cyclic loading with a constant amplitude.