• Bulletin of the Korean Mathematical Society
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• v.55 no.4
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• pp.1303-1315
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• 2018

For principal component analysis (PCA) to efficiently analyze large scale matrices, it is crucial to find a few singular vectors in cheaper computational cost and under lower memory requirement. To compute those in a fast and robust way, we propose a new stochastic method. Especially, we adopt the stochastic variance reduced gradient (SVRG) method [11] to avoid asymptotically slow convergence in stochastic gradient descent methods. For that purpose, we reformulate the PCA problem as a unconstrained optimization problem using a quadratic penalty. In general, increasing the penalty parameter to infinity is needed for the equivalence of the two problems. However, in this case, exact penalization is guaranteed by applying the analysis in [24]. We establish the convergence rate of the proposed method to a stationary point and numerical experiments illustrate the validity and efficiency of the proposed method.

• Structural Engineering and Mechanics
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• v.70 no.3
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• pp.367-380
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• 2019

The paper concerns topology and geometry optimization of statically determinate beams with arbitrary number of supports. The optimization problem is treated as a bi-criteria one, with the objectives of minimizing the absolute maximum bending moment and the maximum deflection for a uniform gravity load. The problem is formulated and solved using the Pareto optimality concept and the lexicographic ordering of the objectives. The non-dominated sorting genetic algorithm NSGA-II and the local search method are used for the optimization in the Pareto sense, whereas the genetic algorithm and the exhaustive search method for the lexicographic optimization. Trade-offs between objectives are examined and sets of Pareto-optimal solutions are provided for different topologies. Lexicographically optimal beams are found assuming that the maximum moment is a more important criterion. Exact formulas for locations and values of the maximum deflection are given for all lexicographically optimal beams of any topology and any number of supports. Topologies with lexicographically optimal geometries are classified into equivalence classes, and specific features of these classes are discussed. A qualitative principle of the division of topologies equivalent in terms of the maximum moment into topologies better and worse in terms of the maximum deflection is found.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2003.05a
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• pp.242-248
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• 2003

In this paper, we propose a new heuristic solution for 3D container packing problem for the variable size and the variable kind of freights. First we consider the total cost of container charges, i.e., loading, transportation and handling charges, where the priority of each frights are dealt. By minimizing the total cost of container charges, the kinds of container and its number can be decided automatically. From these factors, we con determine the position in the container and the loading sequence into the container. Finally, by equivalence of freight's weight in container, we can prevent the freight's damage on the handling.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.8
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• pp.3701-3727
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• 2016

Recently Service Function Chaining (SFC) is promising to innovate the network service mode in modern networks. However, a feasible implementation of SFC is still difficult due to the need to achieve functional equivalence with traditional modes without sacrificing performance or increasing network complexity. In this paper, we present a configurable network service chaining (CNSC) mechanism to provide services for network traffics in a flexible and optimal way. Firstly, we formulate the problem of network service chaining and design an effective service chain construction framework based on integrating software-defined networking (SDN) with network functions virtualization (NFV). Then, we model the service path computation problem as an integer liner optimization problem and propose an algorithm named SPCM to cooperatively combine service function instances with a network utility maximum policy. In the procedure of SPCM, we achieve the service node mapping by defining a service capacity matrix for substrate nodes, and work out the optimal link mapping policies with segment routing. Finally, the simulation results indicate that the average request acceptance ratio and resources utilization ratio can reach above 85% and 75% by our SPCM algorithm, respectively. Upon the prototype system, it is demonstrated that CNSC outperforms other approaches and can provide flexible and scalable network services.

• Proceedings of the Korean Association for Survey Research Conference
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• 2002.06a
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• pp.8-34
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• 2002

This paper is concerned with evaluating the fidelity of a non-cognitive test adaptation for use in multiple languages and cultures using two differential item functioning(DIF) techniques: (a) PSIBTEST, and (b) Logistic Discriminant Function Analysis(LDFA). In particular, this study focused on how DIF research can best be extended to the problem of evaluating the equivalence of tests across cultures and languages. The Sixteen Personality Factor (16PF) questionnaire was administered in English to 844 American college students and in Korean to 538 Korean college students. This study attempted to identify the best matching criterion for the translated tests by using both a multivariate matching technique and iterative purification process. The results generally showed a small number of DIF items on each scale, except for scales A and N where about half of the items showed DIF. The choice of matching variables based on a combination of internal measures appeared to have little effect and the iterative purification method was unsuccessful. Finally, the results were discussed and methodological implications were also presented.

• Journal of Information Management
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• v.28 no.3
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• pp.46-73
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• 1997

In these days, there are many studies to improve the effectiveness of retrieval systems. One method is to use thesaurus in the systems. But the establishment of the saurus independently is very difficult and requiers a great deal of time and labor. The goal of this research is to examine which problems there are. The texts used in the thesis were "Thesaurus of ERIC descriptors(7th ed.1977)" and "KEID Thesaurus(1981)" established by translation. The results of the thesis were as follows, First, there were many differences of equivalence classes of terms between English and Korean. Second, the errors of translation made words inadequate to use as a descriptors. Third, because of differences of traditions, thought and culture, associative relationship and hierarchical relation did not coincide between terns, Fourth, because the terms of the thesaurus of ERIC descriptors serve Western usages, the terms used in Korea were not or insufficient. So it way necessary to add our own therms. As mentioned above, translating a thesaurus for use as a documentation language for indexing and retrieval is not the optimum way of building up a thesaurus.

• Nuclear Engineering and Technology
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• v.47 no.7
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• pp.791-803
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• 2015

The effective cross sections (XSs) in the direct whole core calculation code nTRACER are evaluated by the equivalence theory-based resonance-integral-table method using the WIMS-based library as an alternative to the subgroup method. The background XSs, as well as the Dancoff correction factors, were evaluated by the enhanced neutron-current method. A method, with pointwise microscopic XSs on a union-lethargy grid, was used for the generation of resonance-interference factors (RIFs) for mixed resonant absorbers. This method was modified by the intermediate-resonance approximation by replacing the potential XSs for the non-absorbing moderator nuclides with the background XSs and neglecting the resonance-elastic scattering. The resonance-escape probability was implemented to incorporate the energy self-shielding effect in the spectrum. The XSs were improved using the proposed method as compared to the narrow resonance infinite massbased method. The RIFs were improved by 1% in $^{235}U$, 7% in $^{239}Pu$, and >2% in $^{240}Pu$. To account for thermal feedback, a new feature was incorporated with the interpolation of pre-generated RIFs at the multigroup level and the results compared with the conventional resonance-interference model. This method provided adequate results in terms of XSs and k-eff. The results were verified first by the comparison of RIFs with the exact RIFs, and then comparing the XSs with the McCARD calculations for the homogeneous configurations, with burned fuel containing a mixture of resonant nuclides at different burnups and temperatures. The RIFs and XSs for the mixture showed good agreement, which verified the accuracy of the RIF evaluation using the proposed method. The method was then verified by comparing the XSs for the virtual environment for reactor applicationbenchmark pin-cell problem, as well as the heterogeneous pin cell containing burned fuel with McCARD. The method works well for homogeneous, as well as heterogeneous configurations.

• Asian Journal for Public Opinion Research
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• v.9 no.2
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• pp.188-211
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• 2021

Decreasing response rates to traditional survey methods, like face-to-face and telephone interviews, have led survey practitioners around the world to seek new ways of conducting surveys in recent years." The COVID-19 pandemic exacerbated this problem because it made conducting face-to-face interviews even more difficult than before. For example, it made conducting face-to-face surveys infeasible in 2020 in South Korea, and so the Korean Academic Multimode Open Survey (KAMOS) was unable to conduct a planned face-to-face survey to recruit new panel members. The entire 8,514-member panel, established via two-stage probability-based sampling from 2016 to 2019, was invited to take three online/telephone surveys in 2020. Of these panel members, 1,352 responded to at least one survey in 2020. To test to what extent the panel remained representative of the adult South Korean population, we compared the two groups of panel members: those who responded to at least one survey in 2020 and those who did not. After weighting both groups on the basis of age, sex, and geographical area, we analyzed their responses to some of the questions that were asked during multiple rounds of the face-to-face panel-recruiting interviews. Using Cohen's d for survey items that could be analyzed numerically and Cramér's V for categorical items, we were able to conclude that the respondents to the 2020 surveys were equivalent to the non-respondents in terms of both demographics and in the answers they originally gave to substantive questions on a variety of topics related to social science or public opinion research, including questions about quality of life, societal issue, and politics (Cohen's d items <0.2, 95% CI; Cramér's V items <0.1, 95% CI). This analysis may provide a model for others who wish to test the continued representativeness of their panel or who would like to use a different survey mode or change some other aspect of their methodology and test whether it is equivalent to their former methodology. Our success in building a panel that retained its representativeness may be useful to those in other countries where face-to-face surveys had previously been the norm but are becoming increasingly difficult to conduct.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.7
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• pp.1351-1362
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• 1992

Qualitative models in model-based expert system needs modeling paradigm which provides intelligent control of modeling assumptions and extracts robust inferences without quantitative information about the system to be modeled. Qualitative reasoning methodologies has proved the property of the completeness but not the soundness to the corresponding quantitative model. We propose new methodology of qualitative reasoning by introducing the concept of Centroid-Oriented Composite Interval to improve the soundness problem. Arithmetic operations and equivalence classes were composed using this definition. Qualitative simulation results were compared to Kuipers's results and the improvements in the soundness problem is verified.

• Journal of East-West Nursing Research
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• v.26 no.1
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• pp.80-90
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• 2020

Purpose: Sex education should be given priority to address dating violence. Comprehensive sex education has been developed based on a nonviolent communication model between couples for the smooth resolution of problems with the opposite sex. The purpose of this study was to develop and apply Comprehensive Sex Education for unmarried couples in their 20s-30s and to examine the effects on sex communication, problem-solving communication, and relationship competence. Methods: This study developed a total of six web-based sex education sessions. A comprehensive sex education program combined with nonviolent communication between couples was developed based on the UNESCO Sex Education Guidelines. A pre- and post-equivalence control design was used to provide moderation-based sex education to compare the effects on gender communication, communication dissatisfaction, and relationship development. Results: We developed a comprehensive sex education program for couples that took three minutes per episode, on a web-based basis. Sex communication, problem-solving communication, and love relationship competence showed significant pre- and post-test differences between the experimental and control groups. Conclusion: The program of this study is an attempt to introduce Korea to comprehensive sex education, which has already been shown to be effective through numerous verification processes abroad and will provide assistance in forming future relationships between lovers.