• Journal of KIISE:Information Networking
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• v.37 no.3
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• pp.167-174
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• 2010

Recently the distributed topology control algorithm for constructing the Recrystallization Topology in the unstructured peer-to-peer network was proposed. In this paper, we prove that such a hierarchical topology is a scale-free power-law network. We present a model of a construction process of the distributed protocol, and analyze it based on a mean-field approximation and the continuum theory, so that we show that the constructed Recrystallization Topology is a scale-free network. In the proposed model, all nodes are born with some initial attractiveness and the system incorporates the rewiring of some links at every time step. Some old links are removed with the anti-preferential probability, and some new links are added with preferential probability. In other words, according to the distributed algorithm, each node makes connections to the more-preferential nodes having higher hit-ratio than other nodes, while it disconnects the anti-preferential nodes having lesser hit-ratio. This gives a realistic description of the local processes forming the recrystallization topology in unstructured peer-to-peer network. We calculate analytically the degree distribution. The analytic result indicates that the constructed network is a scale-free network, of which the scaling exponent is 3.

• Journal of Ocean Engineering and Technology
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• v.20 no.6 s.73
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• pp.35-40
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• 2006

In recent years, there's been strong demand for seawalls that havea gentle slope and permeability that serveswater affinity and disaster prevention from wave attack. The aim of this study is to examine wave transformation, including wave run-up that propagates on the coastal structures. A numerical model based on the weak nonlinear dispersive Boussinesq equation, together with the unsteady nonlinear Darcy law for fluid motion in permeable layer, is developed. The applicability of this numerical model is examined through Deguchi and Moriwaki's hydraulic model test on the permeable slopes. From this study, it is found that the proposed numerical model can predict wave transformation and run-up on the gentle slope with a permeable layer, but can't show accurate results for slopes steeper than about 1:10.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.11
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• pp.1603-1609
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• 1998

Numerical solutions of Stokes flow through periodic arrays of cylinders were sought using Darcy's law and homogenization theory. Drag and lift forces of each cylinder were computed for various attack angles and pitch-to-diameter ratios. It was found that drag force decreased as principal pressure gradient direction deviated from array direction and that drag force increased exponentially as pitch-to-diameter ratio approached unity. Similar tendency was found in lift force except that lift force increased and then decreased in quadratic manner as attack angle varied.

• Proceedings of the Korean Society for Quality Management Conference
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• 2004.04a
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• pp.13-18
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• 2004

국내의 제조업과 서비스업은 글로벌 환경, 지식정보화시대, 개방화 등 극심한 경영환경 변화에 노출되어 있다. 적자생존의 법칙이 적용되는 경영현장에서 기업이 지속적으로 성장하기 위해서는 차별적인 경쟁전략이 요구된다고 하겠다. 제품이나 서비스에서 마찬가지로 오차 또는 불량은 고객의 불만과 불평으로 이어져 다시 신뢰를 회복하기 어려울 뿐만 아니라 매출신장이나 서비스 재 구매에도 악영향을 미치게 된다. 따라서 제조업을 막론하고 서비스업에서는 완벽한 품질을 추구해야 한다. 완벽한 품질을 지향하는 것이 '6 시그마'라고 할 수 있다. 1999년 이래로 국내 제조업에서 6시그마 도입이 본격화되면서 서비스업종에서도 6시그마 도입이 점차 증가하고 있고 6시그마 도입에 관심을 갖는 업체들이 늘어나고 있는 추세이다. 본 연구에서는 국내 서비스 기업의 6시그마경영활동과 성과사례를 연구하고 6시그마 도입을 통해서 프로세스측면에서 얻은 경영성과를 확인하고 주요 성공요인들(CSF: Critical Success Factor)을 탐색하기로 한다.

• Journal of Information Management
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• v.24 no.4
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• pp.24-42
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• 1993

This study examines the obsolescence of library and information science literature published in Korea, analysing citations appeared in major periodicals of 1992. Periodicals, languages, and forms of cited literatures are analyzed to find the half-life and the annual aging factors of Korean library and information science literature and then synthesized.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.2
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• pp.19-25
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• 2004

The linear analysis for the balance of linear momentum of a structure is relatively easy to perform, but the error becomes large when the structure experiences large deformation. Therefore, the material and geometric nonlinearity need to be considered for the precise calculations in that case. The plastic flow of a ductile steel-like metal mainly transforms its dissipated mechanical energy into heat, which transfers under the first and second law of thermodynamics. This heat increases the temperature of the material and the strength of the material decreases accordingly, which affects mechanical behavior of the given structure. This paper presents a finite-strain thermo-elasto-plastic steel model. This model can handle large deformation and thermal load simultaneously, which is common during earthquake periods. Two 3-dimensional finite element analyses verify this formulation.

• Journal of the Korean Applied Science and Technology
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• v.40 no.5
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• pp.1001-1009
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• 2023

Flow is a concept closely related to intrinsic motivation and is considered a positive factor in sports performance in sports psychology. The purpose of this study was to confirm the addictive nature of Flow through previous studies and propose a new hypothesis that Flow may decrease intrinsic motivation in the long term, unlike previous studies. In line with adaptation level theory and the law of diminishing marginal utility, the satisfaction derived from Flow is continuously decreasing. At some point, the individual's progress is limited and they reach a point where they no longer experience FLOW. However, the individual will continue to try because the desire to experience FLOW again exists. However, failure to experience FLOW and repeated failure will lead to sadness, which will decrease intrinsic motivation.

• Journal of Science Education
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• v.38 no.1
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• pp.103-119
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• 2014

The purpose of this study was to investigate orientation toward teaching of science teachers had shown in lesson on Law of Definite Composition for middle school students and the factors which influenced its formation. To achieve this, we collected survey materials by recording and analyzing lessons of 8 teachers, interviewing them, and using CoRe questionnaire. From teachers' activities in lessons, we found their orientation toward science teaching, and through analyzing collected materials, drew the factors which influenced the formation of orientation toward science teaching. The result identified two types of orientation toward science teaching: activity-directional and lecture-directional. The former, activity-directional was categorized further as exploration and non-exploration; the latter as interaction-centered and content delivery. The main factors which affected the formation of orientation toward science teaching were reflective thinking through teaching experiences, interaction with colleagues, consideration on education environment, training as a learner, and their own interest and curiosity. Among them, the reflective thinking through teaching experiences was strongest cause, and teacher's interest and curiosity was even limited, also influenced positively. On the other hand, unlikely other factors, consideration on education setting affected negatively to build teacher's teaching orientation. Interaction with colleagues, training for teachers by universities and graduated schools acted on a bit, but had a limit just for mainly developing science content knowledge.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.5
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• pp.376-382
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• 2014

This paper presents a method to enable a UAV in autonomous flight along a desired path to follow it backwards when a strong headwind prevents the vehicle from proceeding forward. The main purpose of the reverse path following in this study is to return to a mission quickly when the wind becomes weaker. When the nonlinear path following guidance law is used, there are two reference points available in the path following. One of the two points is selected considering a flight direction for calculating a straight-line distance(L) from the vehicle to the point for the path following. An initial heading angle with respect to the wind direction determines whether the reverse path following is feasible or not at the time of the wind is generated. The result of the proposed method based on kinematic model in this study is verified through simulations implemented in Matlab.

• Journal of the Korean earth science society
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• v.33 no.1
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• pp.11-31
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• 2012

Kaula's theory of satellite orbit and Kepler's law are re-visited. All the mathematical steps of derivation are thoroughly shown including the ones, which had been omitted in Kaula's original publication. Particularly in evaluations of the 15 independent Lagrange brackets, simplicity and clarity are attained by using orthogonal property of transformation matrix. Explanations of important physical concepts are included as well in the midway of derivation. One conceptual blunder of Kaula's is corrected.