• Journal of Power Electronics
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• v.16 no.6
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• pp.2119-2128
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• 2016

Due to detection and control errors, some high-frequency harmonics with voltage-source characteristics cause circulating currents in modular inverters. Moreover, the circulating currents are usually affected by the output filters (OF) of each module due to their filter and resonance properties. The interaction among the circulating currents in the modules increase the power loss and reduce system stability and control precision. Therefore, this paper reports the results of a study on the SPWM high-frequency harmonics circulating currents for a double-module VSI. In the paper, an analysis of the circulating-current circuits is briefly described. Next, a mathematic model of the single-module output voltage based on the carrier frequency of SPWM is built. On this basis, through mathematic modeling of high-frequency harmonic circulating currents, the formation mechanism and distribution characteristics of circular currents and their influences are studied in detail. Finally, the influences of the OF on the circulating currents are studied by mainly taking an LC-type filter as an example. A theoretical analysis and experimental results demonstrate some important characteristics. First, the carrier phase shifting of the SPWM for each module is the major cause of the SPWM harmonic circulating currents, and the circulating currents are in an odd distribution around n-times the carrier frequency $n{\omega}_s$, where n = 1, 2, 3, ${\ldots}$. Second, the harmonic circular currents do not flow into the parallel system. Third, the OF can effectively suppress the non-circulating part of the high-frequency harmonic currents but is ineffective for the circulation part, and actually reduces system stability.

• Journal of Korean Academy of Nursing
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• v.47 no.5
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• pp.577-588
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• 2017

Purpose: This study was intended to integrate the evidence of home care service intervention for mothers and children in vulnerable groups through an integrative literature review. Methods: We searched the MEDLINE (PubMED), EMBASE, Cochrane Central Register of Controlled Trials, CINAHL, DBpia databases. The quality of the articles was assessed by one doctoral researcher and verified by one professor of community health nursing who had participated in the systematic review of literature. A framework was developed to identify the intervention patterns in the selected papers and categorize various elements. The extracted intervention elements were grouped into potential themes, which were verified by assessors on whether they clearly reflected the interventions in the papers. Results: Among 878 searched papers, we selected 16 papers after excluding literature that does not satisfy the selection criteria and quality evaluation. The intervention elements of 16 selected papers were categorized into six themes. The extracted intervention elements were divided into the themes of Patient-specific/Situation-specific care planning and intervention, Emphasis on self care competency, Intense home visit by developmental milestone, Reinforcing and modeling mother-child attachment, Communication and interaction across the intervention, Linkage with community resource and multidisciplinary approach. Conclusion: As a result of the analysis of proper interventions of home care services for mothers and children in vulnerable groups, it was found that it is necessary to consider indispensable intervention elements that can standardize the quality of home care services, and conduct studies on developing intervention programs based on the elements.

• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.199-213
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• 2017

Chloride penetration is among the main causes of corrosion initiation in reinforced concrete (RC) structures producing premature degradations. Weather and exposure conditions directly affect chloride ingress mechanisms and therefore the operational service life and safety of RC structures. Consequently, comprehensive chloride ingress models are useful tools to estimate corrosion initiation risks and minimize maintenance costs for RC structures placed under chloride-contaminated environments. This paper first presents a coupled thermo-hydro-chemical model for predicting chloride penetration into concrete that accounts for realistic weather conditions. This complete numerical model takes into account multiple factors affecting chloride ingress such as diffusion, convection, chloride binding, ionic interaction, and concrete aging. Since the complete model could be computationally expensive for long-term assessment, this study also proposes model simplifications in order to reduce the computational cost. Long-term chloride assessments of complete and reduced models are compared for three locations in France (Brest, Strasbourg and Nice) characterized by different weather and exposure conditions (tidal zone, de-icing salts and salt spray). The comparative study indicates that the reduced model is computationally efficient and accurate for long-term chloride ingress modeling in comparison to the complete one. Given that long-term assessment requires larger climate databases, this research also studies how climate models may affect chloride ingress assessment. The results indicate that the selection of climate models as well as the considered training periods introduce significant errors for mid- and long- term chloride ingress assessment.

• Journal of Hydrogen and New Energy
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• v.22 no.5
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• pp.686-698
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• 2011

Mathematical models for char-slag interaction and near-wall particle segregation developed by Montagnaro et. al. were applied to predict various aspects of coal gasification in an up-flow entrained gasifier of commercial scale. For this purpose, some computer simulations were performed using gPROMS as the numerical solver. Typical design parameters and operating conditions of the commercial gasifiers were used as input values for the simulation. Development of a densely dispersed phase of solid carbon was found to have a critical effect on both carbon conversion and ash flow behavior. In general, such a slow-moving phase was turned out to enhance carbon conversion by lengthening the residence time of char or soot particles. Furthermore, it was also found that guiding the transfer of char or soot into the closer part of the wall to coal burner is favorable in terms of gasification efficiency and vitrified ash collection. Finally, to a certain degree densely dispersed phase of carbon showed an yield-enhancing effect of syngas.

• The KIPS Transactions:PartB
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• v.13B no.7 s.110
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• pp.653-662
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• 2006

In ubiquitous computing that is to build computing environments to provide proper services according to user's context, human being's emotion recognition based on facial expression is used as essential means of HCI in order to make man-machine interaction more efficient and to do user's context-awareness. This paper addresses a problem of rigidly basic emotion recognition in context-sensitive facial expressions through a new Bayesian classifier. The task for emotion recognition of facial expressions consists of two steps, where the extraction step of facial feature is based on a color-histogram method and the classification step employs a new Bayesian teaming algorithm in performing efficient training and test. New context-sensitive Bayesian learning algorithm of EADF(Extended Assumed-Density Filtering) is proposed to recognize more exact emotions as it utilizes different classifier complexities for different contexts. Experimental results show an expression classification accuracy of over 91% on the test database and achieve the error rate of 10.6% by modeling facial expression as hidden context.

• Genomics & Informatics
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• v.3 no.4
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• pp.142-148
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• 2005

The immune response-related genes have been suggested to be the most favorable genes for positive selection during evolution. Comparing the entire DNA sequence of chimpanzee chromosome 22 (PTR22) with human chromosome 21 (HSA21), we have identified 15 orthologs having indel in their coding sequences. Among them, interferon-${\alpha}$ receptor-1 gene (IFNAR1), an immuneresponse-related gene, is subjected to comparative genomic analysis. Chimpanzee IFNAR1 showed the same genomic structure as human IFNAR1 (11 exons and 10 introns) except the 3 bp insertion in exon 4. The sequence alignment of IFNAR1 coding sequence indicated that 'ISPP' amino acid sequence motif is highly conserved in chimpanzee and other animals including mouse and chicken. However, the human IFNAR1 shows that one proline residue is missing in the sequence motif. The homology modeling of the IFNAR1 structures suggests that the proline deletion in human IFNAR1 leads to the formation of the following ${\alpha}$-helix, whereas two sequential prolines in chimpanzee IFNAR1 inhibit it. As a result, human IFNAR1 may adopt a characteristic structure distinct from chimpanzee IFNAR1. This human specific trait could contribute to specific immune response in the most optimized manner for humans. Further molecular biological studies on the IFNAR1 will help us to gain insights into the molecular implication of species-specific host-pathogen interaction in primate evolution.

• Journal of Digital Contents Society
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• v.13 no.2
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• pp.255-262
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• 2012

Human motion tracking algorithm is receiving attention from many research areas, such as human computer interaction, video conference, surveillance analysis, and game or entertainment applications. Over the last decade, various tracking technologies for each application have been demonstrated and refined among them such of real time computer vision and image processing, advanced man-machine interface, and so on. In this paper, we introduce cost-effective and real-time human motion tracking algorithms based on depth image 3D point matching with a given superellipsoid body representation. The body representative model is made by using parametric volume modeling method based on superellipsoid and consists of 18 articulated joints. For more accurate estimation, we exploit initial inverse kinematic solution with classified body parts' information, and then, the initial pose is modified to more accurate pose by using 3D point matching algorithm.

• Steel and Composite Structures
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• v.20 no.1
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• pp.167-184
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• 2016

This paper presents the details of Finite Element (FE) analysis carried out to determine the limiting deformation capacity and failure mode of Laced Steel-Concrete Composite (LSCC) beam, which was proposed and experimentally studied by the authors earlier (Anandavalli et al. 2012). The present study attains significance due to the fact that LSCC beam is found to possess very high deformation capacity at which range, the conventional laboratory experiments are not capable to perform. FE model combining solid, shell and link elements is adopted for modeling the beam geometry and compatible nonlinear material models are employed in the analysis. Besides these, an interface model is also included to appropriately account for the interaction between concrete and steel elements. As the study aims to quantify the limiting deformation capacity and failure mode of the beam, a suitable damage model is made use of in the analysis. The FE model and results of nonlinear static analysis are validated by comparing with the load-deformation response available from experiment. After validation, the analysis is continued to establish the limiting deformation capacity of the beam, which is assumed to synchronise with tensile strain in bottom cover plate reaching the corresponding ultimate value. The results so found indicate about $20^{\circ}$ support rotation for LSCC beam with $45^{\circ}$ lacing. Results of parametric study indicate that the limiting capacity of the LSCC beam is more influenced by the lacing angle and thickness of the cover plate.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.2
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• pp.75-85
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• 2016

A pyrotechnic system consisting of donor/acceptor pair separated by a gap relies on shock attenuation characteristics of the gap material and shock sensitivity of the donor and acceptor charges. Despite of its common use, numerical study of such pyrotechnic train configuration is seldom reported because proper modeling of the full process requires precise capturing of the shock wave attenuation in the gap prior to triggering a full detonation of high explosive and accurate description of the high strain rate dynamics of the explosively loaded inert confinements. We apply a Eulerian level-set based multimaterial hydrocode with reactive flow models for pentolite donor and heavily aluminized RDX as acceptor charge. The complex shock interaction, critical gap thickness, acoustic impedance, and go/no-go characteristics of the gap test are quantitatively investigated.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2549-2554
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• 2009

The structures of 1,n-alkanedithiol (n = 2, 4, 6, 8, 10) self-assembled monolayers (SAMs) on a Au(111) substrate were investigated by electrochemical measurements and theoretical calculations. The results of the experimental techniques indicated that the dithiols, except n = 2, showed an upright molecular structure in the SAMs, in which alkanedithiols were bound to the Au surface via only one thiol functionality and the other one faced up to the air. The results also suggested that the formed dithiol SAMs were densely packed and highly oriented. Except ethanedithiol, which was thought to form a bilayer, the reductive desorption peak potentials of 1,n-alkanedithiol (n = 4, 6, 8, 10) SAMs were more negative than those of the corresponding monothiol ones in 0.1 M KOH solutions. This illustrates that the dithiol SAMs had higher stability than the corresponding monothiol ones. The major part of the high stability may be attributed to the van der Waals interaction among the sulfur atoms on top of the dithiol SAMs. The molecular modeling calculation showed that the structures of dithiol SAMs were similar to those of the corresponding monothiol SAMs and that all the dithiol SAMs, except ethanedithiol, were more stable than the corresponding monothiol SAMs. The calculated energy differences between dithiol and monothiol SAMs decreased with the increment of alkyl-chain length.