• Journal of Communications and Networks
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• v.10 no.3
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• pp.351-361
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• 2008

This paper presents a delay-margin based traffic engineering (TE) approach to provide end-to-end quality of service (QoS) in multi-protocol label switching (MPLS) networks using differentiated services (DiffServ) at the link level. The TE, including delay, class, and route assignments, is formulated as a nonlinear optimization problem reflecting the inter-class and inter-link dependency introduced by DiffServ and end-to-end QoS requirements. Three algorithms are used to provide a solution to the problem: The first two, centralized offline route configuration and link-class delay assignment, operate in the convex areas of the feasible region to consecutively reduce the objective function using a per-link per-class decomposition of the objective function gradient. The third one is a heuristic that promotes/demotes connections at different links in order to deal with concave areas that may be produced by a trunk route usage of more than one class on a given link. Approximations of the three algorithms suitable for on-line distributed TE operation are also derived. Simulation is used to show that proposed approach can increase the number of users while maintaining end-to-end QoS requirements.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.426-433
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• 2002

This paper deals with an offline routing problem, which can be used as an explicit routing procedure in MPLS(Multiprotocol Label Switching) network, for traffic engineering. This problem is formulated as an MIP(Mixed Integer Programming) with the objective function which is to minimize the sum of the maximum link utilization for load balancing (link utilization) and the routing cost. Constraints arc composed of link capacity restriction and demand requirement that has origin-destination pair, bandwidth requirement and hop restriction. The problem is proved to be NP-hard so that the Lagrangean relaxation method is applied to propose a Lagrangean heuristic. To test the effectiveness & efficiency of the proposed algorithm, computational experiments are performed with numerical instances. The experiment results show that the proposed algorithm solves the problem within a reasonable time.

• Journal of Engineering Education Research
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• v.23 no.6
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• pp.60-67
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• 2020

This study was conducted to understand the experiences of engineering college professors teaching classes online due to COVID-19. Instructional strategies were proposed based on these results. This study qualitatively analyzed interviews of four engineering college professors who switched from teaching classes offline to teaching them online in the first semester of 2020. The results showed that the professors had difficulties in creating video content, interacting with students, and conducting online assessments. The results also showed that the professors had difficulties in switching to online teaching. This study was significant in that it produced empirical data about online teaching based on the experiences of engineering college professors teaching classes online.

• Journal of Digital Convergence
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• v.13 no.7
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• pp.79-88
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• 2015

This study focused on the idea that consumers who are dissatisfied with their body form tend to be more interested in weight control behavior. This research connects this relationship with consumers' risk perception on the internet and consequent decision hesitation behavior. Empirical results extracted three factors of weight control behavior: diet, physical treatment, and medication and exercise. Weight control behavior was different by gender but not by age. Consumers who were dissatisfied with their body form were likely to do exercise, but other types of dissatisfaction (weight dissatisfaction and height dissatisfaction) were not significantly related to weight control behavior. Weight dissatisfaction influenced perceived size risk significantly when shopping online. Diet, physical treatment, and medication had significant influence on perceived size risk when shopping online. Perceived size risk had significant influence on decision delay and offline switch behavior. This study took a convergence approach, which connects consumer characteristics with online shopping behavior.

• Journal of Convergence for Information Technology
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• v.12 no.4
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• pp.328-337
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• 2022

The importance of online marketing is emerging due to the prevalence of COVID-19. In order to respond to the changing business environment, we have collected ten years of sales data of SME bakery company that have experienced a decrease in sales due to the COVID-19. As a result of the analysis, we found that switching from offline markets to omnichannel B2B and B2C markets and taking 'small quantity batch production' to 'mass production in a small variety can improve management. This study presented online and offline marketing strategies through data analysis of small and medium-sized bakery companies, which have relatively insufficient digital capabilities compared to large companies, and could be a guideline for many SMEs.

• The Journal of Society for e-Business Studies
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• v.21 no.3
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• pp.51-78
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• 2016

Online-to-offline (O2O) commerce is the new trend that merges online commerce with traditional industries in various fields. The primary purpose of this paper is to find out which factors influence customers' intention to switch from call-based driver-for-hire services to O2O app-based services. This study used variables and factors based on Theory of Switching Intention, and Extended Unified Theory of Acceptance and Use of Technology in order to design research questions. We surveyed 500 users of call-based driver-for-hire services. According to the result of this study, dissatisfaction with the current call-based driver-for-hire services is estimated to be a significant factor that strengthens customers' intention to switch from the call-based driver-for-hire services to the app-based services. Loyalty to the previous call-based driver-for-hire services was not seen as a crucial motivator that causes customers to switch to the new O2O driver service. Switching cost also did not play a key role in explaining the relationship between dissatisfaction with the current call-based service and the intention to use the new app-based service. Performance expectancy, easiness in use, the level of user's knowledge or available assistance in relation to the use of app-based services, and expectancy for reasonable price was found to have meaningful impacts on customers' intention to switch from the call-based driver-for-hire services to the app-based services. Age, gender and user experience on the new service were found incapable of moderating the relationship between aforementioned factors which influence customers' choice of the app-based driver-for-hire service, and customers' intent to switch to the app-based service.

• Journal of Power Electronics
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• v.9 no.6
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• pp.911-918
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• 2009

This paper presents a new sensorless control method for single-phase switched reluctance motors using induced electromotive force (EMF) due to the residual flux both on the stator and the rotor during phase commutation. The induced EMF falls to zero when the rotor pole moves away from the overlap with the stator pole. By detecting this instant, the speed and position of the rotor can be simply estimated. This method is very simple to implement and it is insensitive to variations in the system parameters as it does not require any stored magnetic data or offline inductance measurements but requires only measurements of the terminal voltage and a simple analog circuit. The proposed method is implemented on a 6/6 single-phase switched reluctance motor. However, it can also be implemented on a multiphase SRM regardless of the size, operation speed and switching mode of the motor hence making the proposed method viable to many applications. Simulation and experimental verification is provided to demonstrate the feasibility of the proposed method.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1137-1145
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• 2017

This paper proposes the dead time effect compensation algorithm using proportional resonant controller in pulse width modulation inverter of motor drive. To avoid a short circuit in the dc link, the dead time of the switch device is surely required. However, the dead time effect causes the phase current distortions, torque pulsations, and degradations of control performance. To solve these problems, the output current including ripple components on the synchronous reference frame and stationary reference frame are analyzed in detail. As a results, the distorted synchronous d-and q-axis currents contain the 6th, 12th, and the higher harmonic components due to the influence of dead time effect. In this paper, a new dead time effect compensation algorithm using proportional resonant controller is also proposed to reduce the output current harmonics due to the dead time and nonlinear characteristics of the switching devices. The proposed compensation algorithm does not require any additional hardware and the offline experimental measurements. The experimental results are presented to demonstrate the effectiveness of the proposed dead time effect compensation algorithm.

• Journal of Environmental Health Sciences
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• v.38 no.6
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• pp.561-567
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• 2012

Objectives: Parabens are widely used as antimicrobial agents in pharmaceuticals and cosmetics as well as by the food industry. Parabens have been reported to show weak estrogenic activity and be related to health effects such as allergic reactions and skin and breast cancer. We evaluated an online solid phase extraction (SPE) method coupled with LC-MS/MS technique using free and conjugated parent parabens in human urine for assessing human exposure to parabens. Methods: We employed LC/MS/MS through online solid phase extraction and column-switching techniques and analyzed free and conjugated parabens as biomarkers of human exposure. Four major parabens, methyl-paraben (MP), ethyl-paraben (EP), propyl-paraben (PP) and butyl-paraben (BP), were analyzed. Method validation was performed by sensitivity, accuracy, precision and comparison of the results of online SPE with offline SPE. Results: The limits of detection (LOD) were in the range of 0.2-2 ng/mL, and actual limits of quantification (LOQ) were in the range of 0.7-6 ng/mL urine, depending upon the compound. Accuracy was in the range of 98.3-106.4%, and precision was in the range of 1.3-8.7% (CV) depending upon the compound. We found a good correlation between the results of analysis by online SPE method and that by off-line SPE method. Conclusions: The online SPE method showed proper LOD and validated accuracy, precision and good correlation with the offline method for analyzing parabens in urine.

• Journal of Digital Convergence
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• v.10 no.10
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• pp.289-294
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• 2012

In this paper, we take advantage of the characteristics of mobile smartphones can be serviced without the constraints of time and space, and Study was developed by a variety of mobile services were done in a traditional offline can be implemented in real-time Case Management Community. To this end, in addition to general PC/laptop, smart mobile until the configuration interface provide the same environment for HTML5 Web Switching and Optimal Network on the same device-specific browser Size to the implementation of the next generation of Web standards, HTML5-based integrated case management Web and Mobile Web. Hybrid App Development OS supports various kinds of smart devices based on SenchaTouch Mobile Framework between the server real-time synchronization and message through the implementation of the Push Notification function, administrators and guardians real-time two-way communication between the subjects is a real-time implementation of the system was implemented Case Management Community.