• Steel and Composite Structures
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• 제28권1호
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• pp.99-110
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• 2018

In this paper, a new size-dependent quasi-3D plate theory is presented for wave dispersion analysis of functionally graded nanoplates while resting on an elastic foundation and under the hygrothermaal environment. This quasi-3D plate theory considers both thickness stretching influences and shear deformation with the variations of displacements in the thickness direction as a parabolic function. Moreover, the stress-free boundary conditions on both sides of the plate are satisfied without using a shear correction factor. This theory includes five independent unknowns with results in only five governing equations. Size effects are obtained via a higher-order nonlocal strain gradient theory of elasticity. A variational approach is adopted to owning the governing equations employing Hamilton's principle. Solving analytically via Fourier series, these equations gives wave frequencies and phase velocities as a function of wave numbers. The validity of the present results is examined by comparing them with those of the known data in the literature. Parametric studies are conducted for material composition, size dependency, two parametric elastic foundation, temperature and moisture differences, and wave number. Some conclusions are drawn from the parametric studies with respect to the wave characteristics.

• 대한간호학회지
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• 제50권6호
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• pp.848-862
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• 2020

Purpose: The purpose of this study was to develop an instrument to evaluate the needs satisfaction of nurses and examine its validity and reliability. Methods: The initial items for the instrument were developed through a literature review and interviews, using the conceptual framework of Maslow's hierarchy of needs theory. The initial items were evaluated for content validity by 14 experts. Four hundred and eighty-six clinical nurses participated in this study through offline and online surveys to test the reliability and validity of the instrument. The first evaluation (n = 256) was used for item analysis and exploratory factor analysis, and the second evaluation (n = 230) was used to conduct a confirmatory factor analysis and to assess the criterion-related validity and internal consistency of the instrument. Test-retest reliability was analyzed using data from 30 nurses. Results: The final instrument consisted of 30 items with two sub-factors for five needs that were identified through the confirmatory factor analysis. The criterion-related validity was established using the five need satisfaction measures (r = .56). Cronbach's α for total items was .90, and test-retest reliability was .89. Conclusion: The findings from this study indicate that this instrument has sufficient validity and reliability. This instrument can be used for the development of nursing interventions to improve the needs satisfaction of clinical nurses.

• Computers and Concrete
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• 제19권6호
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• pp.725-736
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• 2017

This paper presents the two-, three-, and four-lane transverse reduction factor based on FEA method, probability theory, and the recently actual traffic flow data. A total of 72 composite girder bridges with various spans, number of lanes, loading mode, and bridge type are analyzed with time-varying static load FEA method by ANSYS, and the probability models of vehicle load effects at arbitrary-time point are developed. Based on these probability models, in accordance to the principle of the same exceeding probability, the multi-lane transverse reduction factor of these composite girder bridges and the relationship between the multi-lane transverse reduction factor and the span of bridge are determined. Finally, the multi-lane transverse reduction factor obtained is compared with those from AASHTO LRFD, BS5400, JTG D60 or Eurocode. The results show that the vehicle load effect at arbitrary-time point follows lognormal distribution. The two-, three-, and four-lane transverse reduction factors calculated by using FEA method and probability respectively range between 0.781 and 1.027, 0.616 and 0.795, 0.468 and 0.645. Furthermore, a correlation between the FEA and AASHTO LRFD, BS5400, JTG D60 or Eurocode transverse reduction factors is made for composite girder bridges. For the two-, three-, and four-lane bridge cases, the Eurocode code underestimated the FEA transverse reduction factors by 27%, 25% and 13%, respectively. This underestimation is more pronounced in short-span bridges. The AASHTO LRFD, BS5400 and JTG D60 codes overestimated the FEA transverse reduction factors. The FEA results highlight the importance of considering span length in determining the multi-lane transverse reduction factors when designing two-lane or more composite girder bridges. This paper will assist bridge engineers in quantifying the adjustment factors used in analyzing and designing multi-lane composite girder bridges.

• Advances in materials Research
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• 제8권4호
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• pp.313-335
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• 2019

The objective of the present paper is to investigate the bending and free vibration behavior of functionally graded material (FGM) sandwich rectangular plates using an efficient and simple higher order shear deformation theory. Unlike other theories, there are only four unknown functions involved, as compared to five in other shear deformation theories. The most interesting feature of this theory is that it does not require the shear correction factor. Two common types of FGM sandwich plates are considered, namely, the sandwich with the FGM facesheet and the homogeneous core and the sandwich with the homogeneous facesheet and the FGM core. The equation of motion for the FGM sandwich plates is obtained based on Hamilton's principle. The closed form solutions are obtained by using the Navier technique. A static and free vibration frequency is given for different material properties. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions.

• 대한조선학회지
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• 제17권3호
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• pp.5-17
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• 1980

A basic procedure to design marine propellers by a curved lifting line theory was shown. By adapting discrete singularity method, it became possible to take into account of skew, rake and the contraction of slip stream in the early stage of preliminary design procedure. It is also shown that lifting line theory based on the discrete singularity method converges to a common solution obtained by induction factor method with a relatively small number of discrete elements. Lifting the blade geometry more accurately on the basis of hydrodynamic principles. A number of numerical results from lifting line calculation are presented for the purpose of comparison with the previous method, and with these results two sample designs are carried out, which are wake-adapted optimum and wake-adapted non-optimum propellers.

• Earthquakes and Structures
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• 제18권4호
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• pp.481-492
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• 2020

A New hyperbolic shear deformation theory is developed for the bending analysis of softcore and hardcore functionally graded sandwich beams. This theory satisfies the equilibrium conditions at the top and bottom faces of the sandwich beam and does not require the shear correction factor. The governing equations are derived from the principle of virtual work. Sandwich beams have functionally graded skins and two types of homogenous core (softcore and hardcore). The material properties of functionally graded skins are graded through the thickness according to the power-law distribution. The Navier solution is used to obtain the closed form solutions for simply supported FGM sandwich beams. The accuracy and effectiveness of proposed theory are verified by comparison with previous research. A detailed numerical study is carried out to examine the influence of the deflections, stresses, and sandwich beam type on the bending responses of functionally graded sandwich beams.

• Steel and Composite Structures
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• 제7권2호
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• pp.119-133
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• 2007

Based on stability theory of current rigid steel frames and using the three-column subassemblage model, the governing equations for determining the effective length factor (${\mu}$-factor) of the columns in semirigid composite frames are derived. The effects of the nonlinear moment-rotation characteristics of beam-to-column connections and composite action of slab are considered. Furthermore, using a two-bay three-storey composite frame with semi-rigid connections as an example, the effects of the non-linear moment-rotation characteristics of connections and load value on the ${\mu}$-factor are numerically studied and the ${\mu}$-factors obtained by the proposed method and Baraket-Chen's method are compared with those obtained by the exact finite element method. It was found that the proposed method has good accuracy and can be used in stability analysis of semi-rigid composite frames.

• 한국한의학연구원논문집
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• 제10권2호
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• pp.37-49
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• 2004

In the existing Medical Literatures in Korea and China, there is neither the same book name nor same contents of the Medical Book named ${\ulcorner}$Yoryak(要略)${\lrcorner}$, but in viewing of the different name as written as ${\ulcorner}$GyoinYoryak(敎人要略)${\lrcorner}$, it is considered that written as an unpublished manuscript-book for the purpose of Medical Education in the latter period of Chosun Dynasty. While the author, Songgyesanin(松溪散人) is even anonymous as yet, it is regarded that he was much familiar with medical science as a secluded ascetic aiming for Taoism-like Life In ${\ulcorner}$Yoryak${\lrcorner}$, the contents of Taoism Literature named as ${\ulcorner}$OjangYukbudo(五臟六腑圖)${\lrcorner}$ which was regarded that had been actually initiated since ${\ulcorner}$Euibangyoochui(醫方類聚)${\lrcorner}$ is being quoted thereat, also it attempts to combine with ${\ulcorner}$DonguiBogam(東醫寶鑑)${\lrcorner}$, the typical Medical Literature of Chosun Dynasty. With reference to Cause of Disease, since Chin Moo-Taek(陳無擇) asserted 'Theory of Three-Causes(三因說)' in his Book ${\ulcorner}$Samin Keukilbyungjeung Bangron(三因極一病證方論)${\lrcorner}$, it effects many influences to the coming generation, However, on coming up to ${\ulcorner}$Yoryak${\lrcorner}$, the medical science book of Chosun Dynasty, the 'Theory of Two-Causes(二因說)' which consisted of 'Internal Causes by Seven Emotions' and 'Exterior Causes by Six Harmful Surroundings' is also being asserted. In accordance with this Theory, it refers to the 'Seven Emotions(七情)' as the fundamental factor to possibly weaken the viscera and entrails, and also regards that the Exterior Harmful Surroundings invade to body when the viscera and entrails are under weakened condition. Therefore, since Cause of Disease naming as 'Cause Theory at Neither Interior Nor Exterior' is not tolerable in such Diagnostic System, it is daringly advocating the 'Two Causes Theory', getting free from the viewpoint of 'Three Causes Theory' that Chin Moo-Taek has ever maintained.

• Earthquakes and Structures
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• 제17권5호
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• pp.447-462
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• 2019

This present paper concerned with the analytic modelling for vibration of the functionally graded (FG) plates resting on non-variable and variable two parameter elastic foundation, based on two-dimensional elasticity using higher shear deformation theory. Our present theory has four unknown, which mean that have less than other higher order and lower theory, and we denote do not require the factor of correction like the first shear deformation theory. The indeterminate integral are introduced in the fields of displacement, it is allowed to reduce the number from five unknown to only four variables. The elastic foundations are assumed a classical model of Winkler-Pasternak with uniform distribution stiffness of the Winkler coefficient (kw), or it is with variables distribution coefficient (kw). The variable's stiffness of elastic foundation is supposed linear, parabolic and trigonometry along the length of functionally plate. The properties of the FG plates vary according to the thickness, following a simple distribution of the power law in terms of volume fractions of the constituents of the material. The equations of motions for natural frequency of the functionally graded plates resting on variables elastic foundation are derived using Hamilton principal. The government equations are resolved, with respect boundary condition for simply supported FG plate, employing Navier series solution. The extensive validation with other works found in the literature and our results are present in this work to demonstrate the efficient and accuracy of this analytic model to predict free vibration of FG plates, with and without the effect of variables elastic foundations.

• 한국콘텐츠학회논문지
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• 제15권6호
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• pp.215-226
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• 2015

본 연구에서는 합리적 행동이론을 적용하여 주차규제정책에 대한 태도, 주관적 규범, 집행기관에 대한 신뢰가 직접적으로 주차규제정책에 대한 행동의도와 행동에 어떠한 영향을 미치는지와 간접적으로 행동의도를 매개로 하여 행동에 어떠한 영향을 미치는지를 분석하고, 거주지역과 주택종류에 따른 조절효과를 검증하고자 하였다. 이를 위해 주차규제정책이 적용되고 있는 지역의 정책대상집단을 대상으로 설문조사하고 실증분석하였다. 구조방정식모형에 의한 가설검정결과, 주차규제정책에 대한 태도와 주관적 규범 요인이 행동의도에 각각 정(+)의 영향을 미치는 것으로 나타났으며, 행동에는 태도와 집행기관 요인이 정(+)의 영향을 미치는 것으로 나타났다. 그리고 행동의도를 매개로 하여 행동에도 각각 유의한 영향을 미치는 것으로 나타났다. 주거지역과 주택종류에 따른 조절효과를 검증한 결과, 주거지역에서는 태도와 행동의도 간의 관계에, 주택종류에서는 집행기관과 행동간에 관계에 따른 조절효과는 유의한 것으로 나타났다. 이러한 분석 결과를 토대로 본 연구에서는 주차규제정책에 대한 순응과 불응을 위한 실천적 방향을 제시하였다.