• 대한수학회보
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• 제55권4호
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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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• 제70권3호
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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.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2003년도 춘계공동학술대회논문집
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• pp.242-248
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• 2003

본 논문에서는 다양한 종류와 다양한 크기의 화물에 대해 3차원 적재하는 방법으로서 휴리스틱 기법을 이용한 해법을 제안하였다. 먼저, 컨테이너 비용을 적재비용, 수송비용 및 처리비용의 합으로 나타내며. 화물간 우선순위 및 화물 내에서의 개수 간 우선순위를 적용하였다. 주어진 화물을 적재 공간 및 중량을 만족하면서 위의 컨테이너 비용을 최소화하는 컨테이너 종류 및 개수를 산출하였으며, 적재 시 화물의 팔레타이져 및 디팔레타이져로서 컨테이너 내의 공간 이용률을 극대화시켰다. 마지막으로 화물의 무게 균등화를 고려하여 취급중의 화물의 손상방지를 행하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권8호
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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.

• 한국조사연구학회:학술대회논문집
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• 한국조사연구학회 2002년도 춘계학술대회 발표논문집
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• pp.8-34
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• 2002

이 연구의 주된 목적은 외국의 교육 및 심리검사를 번안하여 사용하는 경우, 번안된 검사와 原 검사간의 평형성 (equivalence)을 경험적으로 측정하기 위하여 차별문항기능기법을 응용하는 것이다. 즉, 평형성이라는 것은 타당한 그룹비교를 위한 하나의 전제조건으로서 이런 평형성이 확립되지 않은 채 번안된 검사들의 무분별한 사용은 바람직하지 않다. 서로 다른 접근법을 가지고 있는 두 개의 차별문항기능기법, 로지스틱 판별분석과 SIBTEST가 상호보완적인 목적으로 이용되었고, 최선의 대응변수를 모색하려는 시도로서 다변량 대응기법과 순환적인 정화기법이 사용되었다. 5개의 하위척도를 가진 외향성 척도 중 3개의 척도에서는 적은 수의 차별기능문항을 발견하였으나, 나머지 2개의 척도에서는 반 이상의 문항에서 차별기능을 추출하였다 마지막으로, 대응변수의 선택에 대한 문제들이 논의되고 있다.

• 정보관리연구
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• 제28권3호
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• pp.46-73
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• 1997

정보검색 시스템의 검색효율성을 높이기 위해 많은 나라에서 시소러스를 구축하여 이용하고 있다. 그러나 시소러스 구축에는 많은 시간과 비용은 물론 전문성이 요구된다. 그러므로 외국의 시소러스를 번역하여 자국어 시소러스를 구축하는 사례를 빈번하게 찾아 볼 수 있다. 이 방법을 채택하는 경우 짧은 시간에 시소러스를 구축할 수 있다는 장점은 있으나 언어적, 문화적 차이 때문에 의미상의 등가성과 의미관계를 나타내는 계층관계와 연관관계가 상호 일치하지 않는 부분이 있을 것으로 여겨진다. 그러므로 본 연구에서는 1977년에 발행된 "Thesaurus of ERIC descriptors(7th ed. 1977)" 제 7판과 이것을 대역하여 한국 교육개발원에서 발행한 "KEDI 교육시소러스(1981)"의 디스크립터들을 비교 연구하여 번역 시소러스의 구축방법에 대한 문제점을 규명하고자 하였다.

• Nuclear Engineering and Technology
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• 제47권7호
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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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• 제9권2호
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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.

• 대한기계학회논문집
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• 제16권7호
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• pp.1351-1362
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• 1992

본 연구에서는 단순한 구간대신에 구간내에 제한된 형태의 가능성 분포를 갖 는 복합구간으로 학장하는 것이다. 그리고 이러한 가능성 분포는 퍼지 집합이론에서 사용되는 것처럼 일반적인 분포형태 전체를 사용하는 것이 아니라, 가능성 분포의 무 게중심만 정의하고 이 무게중심과 구간경계만을 사용하여 시스템 변수가 갖는 정성값 을 나타낸다. 이를 바탕으로 새로운 상태변화와 그 규칙을 정의함으로써 정성 모델 링과 시뮬레이션을 할 수 있는 정성 수학을 공식화하였다.이와 같은 방식으로 구한 정성 모델과 추론방법으로 기존의 논문에 나와 있는 시뮬레이션 결과와 비교하여 본 논문에서 제시한 정성해의 논리적 건전성(soundness)을 보였다.

• 동서간호학연구지
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• 제26권1호
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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.