• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.11
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• pp.3950-3969
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• 2021

Radio Frequency (RF)-based indoor localization technologies play significant roles in various Internet of Things (IoT) services (e.g., location-based service). Most such technologies require that all the devices comply with a specified technology (e.g., WiFi, ZigBee, and Bluetooth). However, this requirement limits its application scenarios in today's IoT context where multiple devices complied with different standards coexist in a shared environment. To bridge the gap, in this paper, we propose a cross-technology localization approach, which is able to localize target nodes using a different type of devices. Specifically, the proposed framework reuses the existing WiFi infrastructure without introducing additional cost to localize Non-WiFi device (i.e., ZigBee). The key idea is to leverage the interference between devices that share the same operating frequency (e.g., 2.4GHz). Such interference exhibits unique patterns that depend on the target device's location, thus it can be leveraged for cross-technology localization. The proposed framework uses Principal Components Analysis (PCA) to extract salient features of the received WiFi signals, and leverages Dynamic Time Warping (DTW), Gradient Boosting Regression Tree (GBRT) to improve the robustness of our system. We conduct experiments in real scenario and investigate the impact of different factors. Experimental results show that the average localization accuracy of our prototype can reach 1.54m, which demonstrates a promising direction of building cross-technology technologies to fulfill the needs of modern IoT context.

• Wind and Structures
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• v.35 no.3
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• pp.177-191
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• 2022

Trains emerging on a streamlined bridge-girder may have salient interference effects on the aerodynamic properties of the bridge. The present paper aims at investigating these interferences by wind tunnel measurements, covering surface pressure distributions, near wake profiles, and flow visualizations. Experimental results show that the above interferences can be categorized into two primary effects, i.e., an additional angle of attack (AoA) and an enhancement in flow separation. The additional AoA effect is demonstrated by the upward-moved stagnation point of the oncoming flow, the up-shifted global symmetrical axis of flow around the bridge-girder, and the clockwise-deflected orientation of flow approaching the bridge-girder. Due to this additional AoA effect, the two critical AoAs, where flow around the bridge-girder transits from trailing-edge vortex shedding (TEVS) to impinging leading-edge vortices (ILEV) and from ILEV to leading-edge vortex shedding (LEVS) of the bridge-girder are increased by 4° with respect to the same bridge-girder without trains. On the other hand, the underlying flow physics of the enhancement in flow separation is the large-scale vortices shedding from trains instead of TEVS, ILEV, and LEVS governed the upper half bridge-girder without trains in different ranges of AoA. Because of this enhancement, the mean lift and moment force coefficients, all the three fluctuating force coefficients (drag, lift, and moment), and the aerodynamic span-wise correlation of the bridge-girder are more significant than those without trains.

• Human Ecology Research
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• v.60 no.3
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• pp.471-481
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• 2022

This study aimed at examining the mediation effects of depressive symptoms on the association between social activity participation and marital satisfaction among couples in later life. The study included 1,196 married couples aged 65 or above who participated in the 7th Korean Longitudinal Study of Aging in 2018. The study variables were husbands' and wives' social activity participation, marital satisfaction, and depressive symptoms. Covariates were individual age, education level, subjective health, couples' household income, and number of children. The Actor-Partner Interdependence Mediation Model (APIMeM) and bootstrapping techniques were used to test the significance of the mediating impacts of depressive symptoms based on the dyadic data structure. The results showed that for both husbands and wives, active participation in social activities had significant effects on increasing marital satisfaction through lowering depressive symptoms. However, only the participation of husbands in social activities was positively associated with their own marital satisfaction by reducing their own and their partner's depressive symptoms. These findings suggest that the active social participation of individuals salient for promoting the quality of marital relationships in later life, particularly for preventing their own and their spouse's depressive symptoms.

• Proceedings of the KSPS conference
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• 1996.10a
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• pp.514-514
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• 1996

Igbo, a new Benue Congo language has a vowel harmony system which, like that of Akan, is based on the pharynx size or tongue root position. In this study we examine Igbo vowel harmony with particular reference to assimilatory patterns of vowels in different harmony sets. This is to gain some insight into the factors involved in Igbo vowel assimilation, and to establish to what extent reports on Akan vowel assimilation are validated in Igbo. Tokens of the eight phonemic vowels of Standard Igbo are recorded from three native speakers of Igbo. The vowels are acoustically investigated (using the LPC analysis of CSL) in individual lexical items and within carefully designed carrier phrases. The F1 and F2 values of the vowels are obtained as these formant values are generally useful in establishing the salient characteristics of vowels. Vowels from the harmony sets are juxtaposed in the carrier phrases to ascertain the extent of assimilation. Results of the investigation show that the F1 values, to a large extend, are enough to characterize these vowels. The (-Expanded) vowels have higher F1 values than their (+Expanded) counterpart. Where there is an overlap in F1 values for some vowels the F1 bandwidth values serve to distinguish between the vowels. The overlap often reported in Akan for /I/ and /e/ on the one hand and /${\mho}$/ and /o/ on the other is not validated in Igbo. While the F1 values for these pairs of vowels are quite similar for one of our speakers, there is an appreciable difference between the F1 values of these vowels for the other two speakers. There is however an overlap for /e/ and /o/ for one of the speakers. Assimilations are generally regressive across word boundaries. It is, however, necessary to point out that the general perceptual impression that one of the vowels completely assimilates to the other, is not borne out by our investigation. Most of our F1 and F2 values for the vowels in individual lexical items are altered in assimilations. This then suggests that assimilation involving these vowels is partial rather than complete. The emerging 'allophones' are acoustically similar to the (+Expanded) vowel involved in the assimilation, that is when vowels from different harmony sets are involved. We conclude that while assimilation of Igbo vowels involves some phonological considerations, phonetic factors appear to be permanent in deciding the final form of the vowels.

• Journal of Radiation Protection and Research
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• v.48 no.1
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• pp.28-43
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• 2023

Background: High-fidelity meteorological data is a prerequisite for the realistic simulation of atmospheric dispersion of radioactive materials near nuclear power plants (NPPs). However, many meteorological models frequently overestimate near-surface wind speeds, failing to represent local meteorological conditions near NPPs. This study presents a new high-resolution (approximately 1 km) meteorological downscaling method for modeling short-range (< 100 km) atmospheric dispersion of accidental NPP plumes. Materials and Methods: Six considerations from literature reviews have been suggested for a new dynamic downscaling method. The dynamic downscaling method is developed based on the Weather Research and Forecasting (WRF) model version 3.6.1, applying high-resolution land-use and topography data. In addition, a new subgrid-scale topographic drag parameterization has been implemented for a realistic representation of the atmospheric surface-layer momentum transfer. Finally, a year-long simulation for the Kori and Wolsong NPPs, located in southeastern coastal areas, has been made for 2016 and evaluated against operational surface meteorological measurements and the NPPs' on-site weather stations. Results and Discussion: The new dynamic downscaling method can represent multiscale atmospheric motions from the synoptic to the boundary-layer scales and produce three-dimensional local meteorological fields near the NPPs with a 1.2 km grid resolution. Comparing the year-long simulation against the measurements showed a salient improvement in simulating near-surface wind fields by reducing the root mean square error of approximately 1 m/s. Furthermore, the improved wind field simulation led to a better agreement in the Eulerian estimate of the local atmospheric dispersion. The new subgrid-scale topographic drag parameterization was essential for improved performance, suggesting the importance of the subgrid-scale momentum interactions in the atmospheric surface layer. Conclusion: A new dynamic downscaling method has been developed to produce high-resolution local meteorological fields around the Kori and Wolsong NPPs, which can be used in short-range atmospheric dispersion modeling near the NPPs.

• Geomechanics and Engineering
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• v.32 no.1
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• pp.69-84
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• 2023

This paper proposes a novel frame element on Winkler-Pasternak foundation for analysis of a non-ductile reinforced concrete (RC) member resting on foundation. These structural members represent flexural-shear critical members, which are commonly found in existing buildings designed and constructed with the old seismic design standards (inadequately detailed transverse reinforcement). As a result, these structures always experience shear failure or flexure-shear failure under seismic loading. To predict the characteristics of these non-ductile structures, efficient numerical models are required. Therefore, the novel frame element on Winkler-Pasternak foundation with inclusion of the shear-flexure interaction effect is developed in this study. The proposed model is derived within the framework of a displacement-based formulation and fiber section model under Timoshenko beam theory. Uniaxial nonlinear material constitutive models are employed to represent the characteristics of non-ductile RC frame and the underlying foundation. The shear-flexure interaction effect is expressed within the shear constitutive model based on the UCSD shear-strength model as demonstrated in this paper. From several features of the presented model, the proposed model is simple but able to capture several salient characteristics of the non-ductile RC frame resting on foundation, such as failure behavior, soil-structure interaction, and shear-flexure interaction. This confirms through two numerical simulations.

• Knowledge Management Research
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• v.23 no.4
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• pp.159-175
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• 2022

As creativity is a crucial attribute for companies' survival and innovative success, many firms encourage and implement ways to promote employee creativity. Previous studies in the dual pathway to creativity model have shown that creativity can be enhanced when either the cognitive flexibility or cognitive persistence path is triggered. Although individuals have different personal traits, prior research has rarely investigated whether one pathway is more effective for a certain personality in promoting creativity than the other. Using attachment theory, we examined the influence of attachment style on the degree of the impact of each path on creativity. Specifically, we hypothesized that securely attached people would show higher creativity only when they use the cognitive flexibility path. Data from the US support our hypothesis. Our research highlights that the link between cognitive flexibility and creativity is salient when securely attached people use the cognitive flexibility path because of the strong fit between secure attachment and flexible thinking.

• Journal of the Korea Society of Computer and Information
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• v.14 no.6
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• pp.1-10
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• 2009

Flash memory has the advantages of nonvolatile, low power consumption, light weight, and high endurance. This enables the flash memory to be utilized as a storage of mobile computing device such as PMP(Portable Multimedia Player). Potable device with a mass flash memory can store various multimedia data such as video, audio, or image. Typical index systems for mobile computer are inefficient to search a form of text like lyric or title. In this paper, we propose a new text index system, named EMTEX(Embedded Text Index). EMTEX has the following salient features. First, it uses a compression algorithm for embedded system. Second, if a new insert or delete operation is executed on the base table. EMTEX updates the text index immediately. Third, EMTEX considers the characteristics of flash memory to design insert, delete, and rebuild operations on the text index. Finally, EMTEX is executed as an upper layer of DBMS. Therefore, it is independent of the underlying DBMS. We evaluate the performance of EMTEX. The Experiment results show that EMTEX can outperform th conventional index systems such as Oracle Text and FT3.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.5
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• pp.1339-1355
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• 2023

Localization is a hot research spot for many areas, especially in the mobile robot field. Due to the weak signal of the global positioning system (GPS), the alternative schemes in an indoor environment include wireless signal transmitting and receiving solutions, laser rangefinder to build a map followed by a re-localization stage and visual positioning methods, etc. Among all wireless signal positioning techniques, Wi-Fi is the most common one. Wi-Fi access points are installed in most indoor areas of human activities, and smart devices equipped with Wi-Fi modules can be seen everywhere. However, the localization of a mobile robot using a Wi-Fi scheme usually lacks orientation information. Besides, the distance error is large because of indoor signal interference. Another research direction that mainly refers to laser sensors is to actively detect the environment and achieve positioning. An occupancy grid map is built by using the simultaneous localization and mapping (SLAM) method when the mobile robot enters the indoor environment for the first time. When the robot enters the environment again, it can localize itself according to the known map. Nevertheless, this scheme only works effectively based on the prerequisite that those areas have salient geometrical features. If the areas have similar scanning structures, such as a long corridor or similar rooms, the traditional methods always fail. To address the weakness of the above two methods, this work proposes a coarse-to-fine paradigm and an improved localization algorithm that utilizes Wi-Fi to assist the robot localization in a geometrically similar environment. Firstly, a grid map is built by using laser SLAM. Secondly, a fingerprint database is built in the offline phase. Then, the RSSI values are achieved in the localization stage to get a coarse localization. Finally, an improved particle filter method based on the Wi-Fi signal values is proposed to realize a fine localization. Experimental results show that our approach is effective and robust for both global localization and the kidnapped robot problem. The localization success rate reaches 97.33%, while the traditional method always fails.

• Safety and Health at Work
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• v.14 no.2
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• pp.201-206
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• 2023

Background: Despite workplaces having policies on fire evacuation, many employees still fail to evacuate when there is a fire alarm. The Reasoned Action Approach is designed to reveal the beliefs underlying people's behavioral decisions and thus suggests causal determinants to be addressed with interventions designed to facilitate behavior. This study is a uses a Reasoned Action Approach salient belief elicitation to identify university employees' perceived advantages/disadvantages, approvers/disapprovers, and facilitators/barriers toward them leaving the office building immediately the next time they hear a fire alarm at work. Methods: Employees at a large public United States Midwestern university completed an online cross-sectional survey. A descriptive analysis of the demographic and background variables was completed, and a six-step inductive content analysis of the open-ended responses was conducted to identify beliefs about leaving during a fire alarm. Results: Regarding consequence, participants perceived that immediately leaving during a fire alarm at work had more disadvantages than advantages, such as low risk perception. Regarding referents, supervisors and coworkers were significant approvers with intention to leave immediately. None of the perceived advantages were significant with intention. Participants listed access and risk perception as significant circumstances with the intention to evacuate immediately. Conclusion: Norms and risk perceptions are key determinants that may influence employees to evacuate immediately during a fire alarm at work. Normative-based and attitude-based interventions may prove effective in increasing the fire safety practices of employees.