• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2017년도 추계학술대회
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• pp.27-29
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• 2017

Container terminals in Northern Vietnam have recorded an impressive development in recent years. This development, however, also raises a fierce competition among local container terminals to attract customers. Beside the handling charges, the vessels' waiting cost is also an important factor that drive the opinion of users in choosing appropriate terminal. This research plans to estimate the waiting cost in different container terminals in Northern Vietnam by building regression equation that describe the relationship between the rate of throughput/capacity and waiting cost/TEU. Queuing theory with the application of Poisson distibution is used to estimate the waiting time of arrival vessels and uncertainty theory is applied to estimate the vessel's daily expenses. Previous studies suggested two different formation of the equation and according to the research results, cubic equation is more suitable in the given case. The research results are also useful for further research which require calculation of waiting cost per TEU in each container terminal in Northern Vietnam.

• Composites Research
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• 제15권4호
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• pp.37-42
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• 2002

면외전단하중(anti-plane shear loading)을 받는 기능경사 압전 세라믹 무한 스트립(functionally graded piezoelectric ceramic strip)의 상하 양쪽 끝단의 중앙에 평행하게 존재하는 유한한 크기의 균열(Griffith crack)에 대한 특이응력(singular stress)과 전기장(electric field)을 선형 압전 이론(theory of linear piezoelectricity)을 이용하여 결정한다. 푸리에 변환(Fourier transform)을 이용하여 복합적분 방정식을 구성하며, 이를 제2종 Fredholm 적분 방정식(Fredholm integral equation of the second kind) 으로 표현한다. 또한 응력세기계수(stress intensity factor)와 에너지 해방률(energy release rate)에 대한 수치 결과를 제시하였다.

• 대한화학회지
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• 제56권5호
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• pp.548-555
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• 2012

Ultrasonic velocity and density measurements have been undertaken for a number of binary liquid mixtures involving different commercial solvent extractants, LIX reagents. The binary mixtures under investigation have been classified under two categories such as polar-polar, and polar-non-polar types. Different theories and relations such as Schaaff's Collision Factor Theory (CFT), Nomoto's relation (NOM), and Van Dael & Vangeel ideal mixing relation (IMR) have been used to evaluate the velocity theoretically for all these binary systems. The relative merits of afore-mentioned theories and relations compared to experimental values of velocity have been discussed in terms of percentage variations. However, the CFT and Nomoto's relation show better agreement with the experimental findings than the ideal mixing relation for all the systems under investigation.

• Smart Structures and Systems
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• 제1권3호
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• pp.309-324
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• 2005

This paper presents an efficient and accurate coupled beam model for piezoelectric bimorphs based on improved first-order shear deformation theory (FSDT). The model combines the equivalent single layer approach for the mechanical displacements and a layerwise modeling for the electric potential. General electric field function is proposed to reasonably approximate the through-the-thickness distribution of the applied and induced electric potentials. Layerwise defined shear correction factor (k) accounting for nonlinear shear strain distribution is introduced into both the shear stress resultant and the electric displacement integration. Analytical solutions for free vibrations and forced response under electromechanical loads are obtained for the simply supported piezoelectric bimorphs with series or parallel arrangement, and the numerical results for various length-to-thickness ratios are compared with the exact two-dimensional piezoelasticity solution. Excellent predictions with low error estimates of local and global responses as well as the modal frequencies are observed.

• 가정과삶의질연구
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• 제4권1호
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• pp.1-13
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• 1986

The purpose of this study was to examine whether the Marital Satisfaction Scale(M.S.S) is properly applicable to Korean couples and further to be devoted to the designed of a marital satisfaction scale for Korea. The scale employed in this study was a Korean adaptation of the M.S.S., which originally included 73 items but was reduced to 48 through a study of its validity by Bowden. This scale was administered to 420 couples. One kindergarten, two elementary schools, one middle school, and four high schools, all of them located in Seoul or its satellite cities were selected for the present study. The results of the study were as follows. 1) Through item analysis, 85.4% of the total items showed a high index of discrimination, i.e, of more than +.40, which all was significant discrimination (P<0.001) excluding two items. 2)Factor analysis, which was oriented toward combining factors proper to theory, showed that the M.S.S. consisted of 6 factors and its total variance was 50.18%. The 6 factors were marital satisfaction (factor 1), marital social psychological companionship (factor 2), obstacles to marriage (factor 3), dissatisfaction of marital relationship (factor 4), attitude of the reasonable marital relationship (factor 5), and cognition of married life (factor 6), 3) internal consistency reliability of the M.S.S. was 0.951 and the reliability of the total items after excluding two through item analysis 0.956 and 0.949 respectively, which showed a high internal consistency 4) The marital satisfaction examined by the M.S.S showed significant differences according to sex, education , income, the duration of marriage, the number of children but no significant differences according to age, and family type. From these results, it will be concluded that the M.S.S is a reliable and valid psychological scale for examining marital satisfaction of Korean couples. The limitations of this study were as follows. 1) It can not be generalized to all Korean couples because the subjects was sampled from Seoul or satellite cities. 2)The factor analysis in this study was oriented toward combining factors proper to theory. However, it was very difficult to find out the factors because the components of the M.S.S. was more or less abstract. Thus, from these results some suggestions follow for developing the marital satisfaction scale proper to Korean couples systematically and scientifically. 1) The subjects must be sampled form urban as well as rural areas 2)Factor analysis in this study is oriented toward finding out factors of the M.S.S. Thus, it is needed to analyze the factor validity or construct validity by multitrait - multimethod of the scale with more theoretical conceptualization. 3) It is necessary to examine whether marital satisfaction shows difference according to couples and psychological variables besides objective demographic variables. 4) More research is needed before the M.S.S. con be adapted into a turely useful marital satisfaction scale for Korea.

• Journal of electromagnetic engineering and science
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• 제16권4호
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• pp.219-224
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• 2016

In this paper, coupled-mode theory (CMT) is used to obtain a transient solution analytically for a wireless power transfer system (WPTS) when unit energy is applied to one of two resonators. The solutions are compared with those obtained using equivalent circuit-based analysis. The time-domain CMT is accurate only when resonant coils are weakly coupled and have large quality factors, and the reason for this inaccuracy is outlined. Even though the time-domain CMT solution does not describe the WPTS behavior precisely, it is accurate enough to allow for an understanding of the mechanism of energy exchange between two resonators qualitatively. Based on the time-domain CMT solution, the critical coupling coefficient is derived and a criterion is suggested for distinguishing inductive coupling and magnetic resonance coupling of the WPTS.

• 한국유체기계학회 논문집
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• 제2권3호
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• pp.52-58
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• 1999

The leakage and rotordynamic coefficients of see-through type gas labyrinth seals are determined using a two-control-volume-model analysis with Moody's wall-friction-factor formula which is defined with a large range of Reynolds number and relative roughness. Jet flow theory are used for the calculation of the recirculation velocity in the cavity. For the reaction force from the labyrinth seal, linearized zeroth-order and the first-order perturbation equations are developed for small motion about a centered position. The leakage and rotordynamic coefficient results of the present analysis are compared with Scharrer's theoretical analysis using Blasius' wall-friction-factor formula and Pelletti's experimental results. The comparison shows that the present analysis using Moody's wall-friction-factor formula and Scharrer's theoretical analysis using Blasius' wall-friction-factor formula give the same results for a smooth seal surface and the range of Reynolds number less than $10^5$.

• Structural Engineering and Mechanics
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• 제64권2호
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• pp.145-153
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• 2017

In this article, a novel simple higher-order shear deformation theory for bending and free vibration analysis of functionally graded (FG) beams is proposed. The beauty of this theory relies on its 2-unknowns displacement field as the Euler-Bernoulli beam theory, which is even less than the Timoshenko beam theory. A shear correction factor is, therefore, not needed. Equations of motion are obtained via Hamilton's principle. Analytical solutions for the bending and free vibration analysis are given for simply supported beams. Efficacy of the proposed model is shown through illustrative examples for bending and dynamic of FG beams. The numerical results obtained are compared with those of other higher-order shear deformation beam theory results. The results obtained are found to be accurate.

• 한국정보통신학회논문지
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• 제16권9호
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• pp.2015-2020
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• 2012

본 연구에서는 이중게이트(Double Gate; DG) MOSFET에 스켈링이론을 적용할 때 두 개의 게이트에 의한 효과를 반영하기 위하여 스켈링인자에 가중치를 적용하여 문턱전압이하 특성을 해석하였다. 포아송방정식에 의한 전위분포를 구하기 위하여 전하분포는 가우스분포함수를 이용할 것이며 이의 타당성은 이미 여러 논문에서 입증하였다. 이 전위분포를 이용하여 단채널효과 중 문턱전압이동, 문턱전압이하 스윙, 드레인유도장벽감소 등을 스켈링인자에 대한 가중치의 변화에 따라 관찰하였다. 이중게이트 MOSFET의 구조적 특성상 채널길이에 대한 가중치는 0.1에서 1까지 사용하였으며 채널두께에 대한 가중치는 1에서 2까지 가중치를 사용하였다. 결과적으로 문턱전압 이하 스윙은 스켈링인자에 따라 거의 변화가 없었으나 가중치에 따라 변화하였으며 문턱전압이동 및 드레인유도 장벽감소 등은 스켈링인자에 따라 그리고 가중치에 따라 큰 변화를 보이는 것을 알 수 있었다.

• 한국정보시스템학회지:정보시스템연구
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• 제23권2호
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• pp.109-137
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• 2014

As the fast development of information technology (IT), abundant attractive alternatives have showed up and challenged to the traditional information technology (IT). Cloud services, the hottest representative among these alternatives, has attracted the attention from all walks of life. Considering the diversity of cloud services, this study attempts to find out the important factors affected on individual's switching intention from incumbent IT to cloud services mainly based on two-factor theory (switching enablers and switching inhibitors) and explore the direct influences of these factors on individual's switching intention. According to our findings, individual's switching intention to cloud services is not only positively influenced by switching enablers but also negatively influenced by switching inhibitors. All the switching enablers in this study (perceived omnipresence, perceived collaboration support and perceived compatibility of cloud services) have positively significant influences on individual's switching intention as well as the switching inhibitors (usage habit of incumbent IT and perceived risk of cloud services) have negatively significant influences on individual's switching intention. It's noteworthy that satisfaction of incumbent IT has insignificant influence on individual's switching intention in this study. Moreover, as we expected, both social influence and personal innovativeness have significant influences on the generation of individual's switching intention.