• Proceedings of the KIEE Conference
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• 1999.11a
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• pp.43-51
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• 1999

The power flow calculations(PFc) are the most important and powerful tools in power systems engineering. The conventional power flow problem is solved generally with numerical methods such as Newton-Raphson(NR). The conventional numerical method generally have some convergency problem, which is sensitive to initial value, and numerical stability problem concerned with jacobian matrix inversion. This paper presents a new PFc algorithm based on the improved genetic algorithm (IGA) which can overcome the disadvantages mentioned above. The parameters of GA, with dynamical hierarchy of the coding system, are improved to make GA a practical algorithm in the problem of real system. Some case studies with test bus system also present to show the performance of proposed algorithm. The results of proposed algorithm are compared with the results of PFc obtained using a conventional NR method.

• International Journal of Fluid Machinery and Systems
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• v.9 no.1
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• pp.57-65
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• 2016

By high speed Liquid Droplet Impingement (LDI) on material, fluid systems are seriously damaged, therefore, it is important for the solution of the erosion problem of fluid systems to consider the effect of material in LDI. In this study, by using an in-house fluid/material two-way coupled method which considers reflection and transmission of pressure, stress and velocity on the fluid/material interface, high-speed LDI on wet/dry material surface is simulated. As a result, in the case of LDI on wet surface, maximum equivalent stress are less than those of dry surface due to damping effect of liquid film. Empirical formula of the damping effect function is formulated with the fluid factors of LDI, which are impingement velocity, droplet diameter and thickness of liquid film on material surface.

• Journal of Mechanical Science and Technology
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• v.17 no.12
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• pp.1938-1948
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• 2003

This paper represents that an enhanced genetic algorithm (EGA) is applied to optimal design of a squeeze film damper (SFD) to minimize the maximum transmitted load between the bearing and foundation in the operational speed range. A general genetic algorithm (GA) is well known as a useful global optimization technique for complex and nonlinear optimization problems. The EGA consists of the GA to optimize multi-modal functions and the simplex method to search intensively the candidate solutions by the GA for optimal solutions. The performance of the EGA with a benchmark function is compared to them by the IGA (Immune-Genetic Algorithm) and SQP (Sequential Quadratic Programming). The radius, length and radial clearance of the SFD are defined as the design parameters. The objective function is the minimization of a maximum transmitted load of a flexible rotor system with the nonlinear SFDs in the operating speed range. The effectiveness of the EGA for the optimal design of the SFD is discussed from a numerical example.

• Advances in nano research
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• v.12 no.5
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• pp.441-455
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• 2022

This study explores the linear and nonlinear solutions of sigmoid functionally graded material (S-FGM) nanoplate with porous effects. A size-dependent numerical solution is established using the strain gradient theory and isogeometric finite element formulation. The nonlinear nonlocal strain gradient is developed based on the Reissner-Mindlin plate theory and the Von-Karman strain assumption. The sigmoid function is utilized to modify the classical functionally graded material to ensure the constituent volume distribution. Two different patterns of porosity distribution are investigated, viz. pattern A and pattern B, in which the porosities are symmetric and asymmetric varied across the plate's thickness, respectively. The nonlinear finite element governing equations are established for bending analysis of S-FGM nanoplates, and the Newton-Raphson iteration technique is derived from the nonlinear responses. The isogeometric finite element method is the most suitable numerical method because it can satisfy a higher-order derivative requirement of the nonlocal strain gradient theory. Several numerical results are presented to investigate the influences of porosity distributions, power indexes, aspect ratios, nonlocal and strain gradient parameters on the porous S-FGM nanoplate's linear and nonlinear bending responses.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.6
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• pp.514-528
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• 2004

An emotion-based video scene retrieval algorithm is proposed in this paper. First, abrupt/gradual shot boundaries are detected in the video clip representing a specific story Then, five video features such as 'average color histogram' 'average brightness', 'average edge histogram', 'average shot duration', and 'gradual change rate' are extracted from each of the videos and mapping between these features and the emotional space that user has in mind is achieved by an interactive genetic algorithm. Once the proposed algorithm has selected videos that contain the corresponding emotion from initial population of videos, feature vectors from the selected videos are regarded as chromosomes and a genetic crossover is applied over them. Next, new chromosomes after crossover and feature vectors in the database videos are compared based on the similarity function to obtain the most similar videos as solutions of the next generation. By iterating above procedures, new population of videos that user has in mind are retrieved. In order to show the validity of the proposed method, six example categories such as 'action', 'excitement', 'suspense', 'quietness', 'relaxation', 'happiness' are used as emotions for experiments. Over 300 commercial videos, retrieval results show 70% effectiveness in average.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.32 no.2
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• pp.68-93
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• 2019

Objective : This study summarized the characteristics of clinical trials for atopic dermatitis medicines approved by the Ministry of Food and Drug Safety(MFDS). This study may be a reference for the design of clinical trials of atopic dermatitis herbal medicine treatment which may be carried out later. Method : The characteristics of the clinical trial were analyzed for clinical trials registered with ClinicalTrials.gov, CRIS, and the Korea Health Industry Development Institute among the clinical trial approval statuses posted on the website of the MFDS. Result : 1. Clinical trial drugs were developed in various formulations such as oral medicines, injections, dermatologic agents, and similar proportions. Relatively little clinical trials were found for herbal medicine. 2. In the control evaluation test, most of the treatments for the control group were performed with placebo using Vehicle. 3. In most clinical trials, one intervention group was in the form of a parallel assignment with only one treatment. 4. The age of the subjects was 11 out of 28 studies including minors, and clinical trials targeting minors were also found to be significant. 5. In the case of atopic dermatitis, the cases of subacute chronic or atopic dermatitis more than 6 months or more than 1 year were often used. 6. Most clinical trials were divided into mild to moderate atopic dermatitis or moderate to severe atopic dermatitis. The SCORAD index, EASI, IGA, BSA, and NRS were used as the evaluation criteria. 7. Regulations for the drugs used prior to the trial period for the treatment of atopic dermatitis vary somewhat from one clinical trial to another. 8. IGA was used most often as a primary efficacy tool, and SCORAD index, EASI, and NRS were also used.

• Steel and Composite Structures
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• v.30 no.6
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• pp.517-534
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• 2019

In this paper, the effects of inevitable out-of-plane defects on the postbuckling behavior of single-layered graphene sheets (SLGSs) under in-plane loadings are investigated based on nonlocal first order shear deformation theory (FSDT) and von-Karman nonlinear model. A generic imperfection function, which takes the form of the products of hyperbolic and trigonometric functions, is employed to model out-of-plane defects as initial geometrical imperfections of SLGSs. Nonlinear equilibrium equations are derived from the principle of virtual work and variational formulation. The postbuckling equilibrium paths of imperfect graphene sheets (GSs) are presented by solving the governing equations via isogeometric analysis (IGA) and Newton-Raphson iterative method. Finally, the sensitivity of the postbuckling behavior of GS to shape, amplitude, extension on the surface, and location of initial imperfection is studied. Results showed that the small scale and initial imperfection effects on the postbuckling behavior of defective SLGS are important and cannot be ignored.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.3
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• pp.155-163
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• 2018

One of the major disadvantages of isogeometric analysis(IGA) is that local refinement is nearly impossible in a conventional manner because of the tensor product nature in NURBS. In this research, we investigate a local refinement scheme for isogeometric analysis, named multi-resolution approach where different resolutions are employed at each subdomain, using h-refinement relation to endow displacement compatibility on an interface of subdomains. Then, we develop shape sensitivity analysis possessing same compatibility condition as in the analysis. Numerical examples are shown to demonstrate the computational efficiency of the method in analysis especially stress concentration problem and accurate sensitivity results which is also compatible on the interface.

• Horticultural Science & Technology
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• v.32 no.4
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• pp.535-543
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• 2014

Backcross breeding is the method most commonly used to introgress new traits into elite lines. Conventional backcross breeding requires at least 4-5 generations to recover the genomic background of the recurrent parent. Marker-assisted backcrossing (MABC) represents a new breeding approach that can substantially reduce breeding time and cost. For successful MABC, highly polymorphic markers with known positions in each chromosome are essential. Single nucleotide polymorphism (SNP) markers have many advantages over other marker systems for MABC due to their high abundance and amenability to genotyping automation. To facilitate MABC in hot pepper (Capsicum annuum), we utilized expressed sequence tags (ESTs) to develop SNP markers in this study. For SNP identification, we used Bukang $F_1$-hybrid pepper ESTs to prepare a reference sequence through de novo assembly. We performed large-scale transcriptome sequencing of eight accessions using the Illumina Genome Analyzer (IGA) IIx platform by Solexa, which generated small sequence fragments of about 90-100 bp. By aligning each contig to the reference sequence, 58,151 SNPs were identified. After filtering for polymorphism, segregation ratio, and lack of proximity to other SNPS or exon/intron boundaries, a total of 1,910 putative SNPs were chosen and positioned to a pepper linkage map. We further selected 412 SNPs evenly distributed on each chromosome and primers were designed for high throughput SNP assays and tested using a genetic diversity panel of 27 Capsicum accessions. The SNP markers clearly distinguished each accession. These results suggest that the SNP marker set developed in this study will be valuable for MABC, genetic mapping, and comparative genome analysis.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.5
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• pp.287-292
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• 2021

We utilized the isogeometric analysis (IGA) method that uses NURBS basis functions in CAD systems, to account for the geometric exactness of a geometrically exact beam deformation, on a new type of metamaterial, twist-translation coupled structure showing a large twist angle. A two-dimensional unit cell structure was embedded in a cylindrical wall, using free-form deformation and an appropriate interpolation scheme. A parametric study on the effects of the dimensions of the cylinder and the number of cells, on the twisting angle was performed. Furthermore, the mechanism of the twist-translation coupled metamaterial was explored through numerical examples.