• Korean Journal of Computational Design and Engineering
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• v.12 no.4
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• pp.255-262
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• 2007

In the finite element analysis of forming process, objects are described with a finite number of elements and nodes and the approximated solutions can be obtained by the variational principle. One of the shortcomings of a finite element analysis is that the structure of mesh has become inefficient and unusable because discretization error increases as deformation proceeds due to severe distortion of elements. If the state of current mesh satisfies a certain remeshing criterion, analysis is stopped instantly and resumed with a reconstructed mesh. In the study, a new remeshing algorithm using tetrahedral elements has been developed, which is adapted to the desired mesh density. In order to reduce the discretization error, desired mesh sizes in each lesion of the workpiece are calculated using the Zinkiewicz and Zhu's a-posteriori error estimation scheme. The pre-constructed mesh is constructed based on the modified point insertion technique which is adapted to the density function. The object domain is divided into uniformly-sized sub-domains and the numbers of nodes in each sub-domain are redistributed, respectively. After finishing the redistribution process of nodes, a tetrahedral mesh is reconstructed with the redistributed nodes, which is adapted to the density map and resulting in good mesh quality. A goodness and adaptability of the constructed mesh is verified with a testing measure. The proposed remeshing technique is applied to the finite element analyses of forging processes.

• Journal of Home Health Care Nursing
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• v.20 no.1
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• pp.44-52
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• 2013

Purpose: To identify factors that affect the job stress of visiting nurses at health centers in Seoul, Korea, who perform home care services. Methods: Data were collected in the period from November 20 to December 10, 2008, from 206 visiting nurses working at 25 health centers in Seoul metropolitan city. Self-report questionnaires of the Organization-Based Self-Esteem (OBSE) and the Korean Occupational Stress Scale (KOSS) were used. Data were analyzed by the SPSS win 15.0. Results: Several findings were obtained from the study. First, the mean of job stress was 52.4 points, which was higher than that of Korean women. Second, it was shown that by the sub-domain of job stress, the mean value belonged to the top 50% in the four sub-domains of physical environment, job demand, interpersonal conflict, and organizational system. Additionally, it belonged to the top 25% in the sub-domain of job insecurity, wherein the job stress was the highest. Third, the self-esteem of the nurses had the most significant effect on their job stress. Conclusion: Stress related to job insecurity was the highest among the visiting nurses at health centers in Seoul who perform the custom home care service thus, institutional support is urgently needed to alleviate such stress and secure their employment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.11
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• pp.1118-1127
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• 2008

The position and size of holes in the partition of a double cavity are known to strongly affect the eigenfrequency of the longitudinal eigenmodes of the double cavity. To maximize or minimize the eigenfrequency of the hole-partitioned double cavity, two acoustical topology optimization problems are formulated and solved. While two sub-cavities are filled with air, a partition between them is assumed to consist of sub-partitions of variable acoustical properties. One design variable is assigned to each sub-partition, whose material properties are interpolated as those of an intermediate material between air and a rigid body. The penalty parameter of the used interpolation function is adjusted to obtain a distinct air and rigid body distribution at the converged stage in each acoustical topology optimization problem. A special attention is paid to the selection of initial values of design variables to obtain solutions as close to global optimum and symmetric as possible. To show numerical characteristics of these optimization problems, the formulated problems are first solved for the one-dimensional partition design domain and then for the two-dimensional partition design domain.

• Communications of the Korean Mathematical Society
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• v.35 no.4
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• pp.1095-1106
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• 2020

The purpose of this paper is to introduce a new class of rings that is closely related to the class of pseudo-Krull domains. Let 𝓗 = {R | R is a commutative ring and Nil(R) is a divided prime ideal of R}. Let R ∈ 𝓗 be a ring with total quotient ring T(R) and define 𝜙 : T(R) → R_Nil(R) by ${\phi}({\frac{a}{b}})={\frac{a}{b}}$ for any a ∈ R and any regular element b of R. Then 𝜙 is a ring homomorphism from T(R) into R_Nil(R) and 𝜙 restricted to R is also a ring homomorphism from R into R_Nil(R) given by ${\phi}(x)={\frac{x}{1}}$ for every x ∈ R. We say that R is a 𝜙-pseudo-Krull ring if 𝜙(R) = ∩ R_i, where each R_i is a nonnil-Noetherian 𝜙-pseudo valuation overring of 𝜙(R) and for every non-nilpotent element x ∈ R, 𝜙(x) is a unit in all but finitely many R_i. We show that the theories of 𝜙-pseudo Krull rings resemble those of pseudo-Krull domains.

• Journal of The Korean Association For Science Education
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• v.40 no.1
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• pp.51-60
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• 2020

In this study, we propose research methods to explore the nature of earth science by applying the phenomenological approach and NOS-family resemblance approach based on literature review. The phenomenological approach exploring the nature of earth science is a method of collecting, analyzing and synthesizing multifaceted features of earth science from intuitive sensory phenomena without prejudice. As a way of exploring the nature of earth science from a phenomenological point of view, we propose the NOS-family resemblance approach to the NOS. This approach provides a comprehensive explanation of NOS by combining the characteristics shared by different areas of science with distinct differences. Applying this method to exploring the nature of earth science, we can identify both domain-general and domain-specific characteristics that make sub-areas of earth science a 'family.' For example, through the networking of features shared by such sub-areas as geology, atmospheric science, oceanography, astronomy, earth system science, etc., we can extract the family-resemblance characteristics that make these sub-areas a family called earth science. Through these approaches to the nature of earth science, the richness, complexity, and dynamic nature of earth science can be revealed as a whole. In addition, we will be able to grasp the change in the sub-areas that constitute the earth science, which in turn changes the nature of earth science, and to contribute to establishing the status and development system of earth science as a school subject.

• Journal of Gifted/Talented Education
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• v.26 no.1
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• pp.37-51
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• 2016

This study examined the friendship expectation that science-gifted and non-gifted elementary students perceived in gifted class and regular class. In 233 science-gifted elementary students and 329 non-gifted elementary students, we measured the friendship expectation that sub-domains were intimacy, ability similarity, and morality. The results of this study were as follows: First, according to the results of comparing the friendship expectations of science-gifted and non-gifted students at the regular class, there was statistically significant intergroup difference in the sub-domains of intimacy and morality, but there was no significant difference in the sub-domain of ability similarity. Second, according to the results of comparing the friendship expectations of science-gifted at the gifted class and at the regular class, there was statistically significant difference in the sub-domain of intimacy, but there was no significant difference in the sub-domains of morality and ability similarity. Based the results, the implications to understand the friendship of the science gifted elementary students were suggested in depth.

• Journal of The Korean Association For Science Education
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• v.18 no.4
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• pp.539-544
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• 1998

The consistency and balance of objectives by objective domains in units, sub-units and instructional units were investigated. The 6th elementary biology curricular teaching guidebooks were analysed. Domains of objectives are cognitive, inquiry process, instrumental skill, creative, affective and STS. Cognitive objectives were most dominant in all units, sub-units and instructional units. But no objective for creative domain were suggested. In unit and sub-unit, proportions of objectives were cognitive, inquiry process, affective, instrumental skill and STS domains in order. Objectives for cognitive and inquiry process domains were more than others in instructional units, Except cognitive and inquiry process domains, objectives for the others were not consistent in all units, sub-units and instructional units. Especially, the percentages of objectives for affective domain decreased in units, sub-units and instructional units orderly. These resulted from teaching objective domains categorized formally, Thus, it is necessary to develope curriculum and textbook to be consistent and balanced with objective domains and reflect upon the characteristics of them.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.3
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• pp.281-285
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• 2008

Eigenvalue reduction schemes approximate the lower eigenmodes that represent the global behavior of the structures. In the previous study, we proposed a two-level condensation scheme (TLCS) for the construction of a reduced system. And we have improved previous TLCS with combination of the iterated improved reduced system method (IIRS) to increase accuracy of the higher modes intermediate range. In this study, we apply previous improved TLCS to multi-level sub-structuring scheme. In the first step, the global system is recursively partitioned into a hierarchy of sub-domain. In second step, each uncoupled sub-domain is condensed by the improved TLCS. After assembly process of each reduced sub-eigenvalue problem, eigen-solution is calculated by Lanczos method (ARPACK). Finally, Numerical examples demonstrate performance of proposed method.

• Journal of Convergence for Information Technology
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• v.8 no.2
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• pp.227-232
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• 2018

The purpose of this study is to investigate the relationship between facial image efficacy and job satisfaction in a sample of 167 workers in SMEs in Seoul and Gyeonggi province. and to examine the effect of SME workers' face image efficacy on job satisfaction. The results of the study are as follows. First, there was a statistically significant correlation between management ability and job satisfaction, which is a sub - area of facial image efficacy. This means that the higher the management ability, the higher the degree of job satisfaction. There was a statistically significant correlation between perception attitude and job satisfaction, which is a sub - area of face image efficacy. Second, management ability, which is a sub - area of face image efficacy of SME workers, has a statistically significant effect on job satisfaction. The sub - domain of face image efficacy has no effect on job satisfaction, Expression confidence, which is a sub-domain of image efficacy, has a statistically significant effect on job satisfaction.

• Speech Sciences
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• v.12 no.2
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• pp.153-170
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• 2005

The sub-Nyquist nonuniform sampling (SNNS) and the perfect reconstruction (PR) formula are proposed for the development of a systematic method to obtain minimal representation of a speech signal. In the proposed method, the instantaneous sampling frequency (ISF) varies, depending on the least upper boundary of spectral support of a speech signal in time-frequency domain (TFD). The definition of the instantaneous bandwidth (IB), which determines the ISF and is used for generating the set of samples that represent continuous-time signals perfectly, is given. Also, the spectral characteristics of the sampled data generated by the sub-Nyquist nonuniform sampling method is analyzed. The proposed method doesn't generate the redundant samples due to the time-varying property of the instantaneous bandwidth of a speech signal.