• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.2
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• pp.399-408
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• 2015

This paper concentrated on the ultimate uniaxial compressive strength of stiffened panel with opening under lateral load and also studied the design-oriented formulae. For this purpose, three series of well executed experiments on longitudinal stiffened panel with rectangular opening subjected to the combined load have been selected as test models. The finite element analysis package, ABAQUS, is used for simulation with considering the large elasticplastic deflection behavior of stiffened panels. The feasibility of the numerical procedure is verified by a good agreement of experimental results and numerical results. More cases studies are executed employing nonlinear finite element method to analyze the influence of design variables on the ultimate strength of stiffened panel with opening under combined pressure. Based on data, two design formulae corresponding to different opening types are fitted, and accuracy of them is illustrated to demonstrate that they could be applied to basic design of practical engineering structure.

• Bulletin of the Society of Naval Architects of Korea
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• v.23 no.4
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• pp.1-10
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• 1986

A container ship, due to wide hatch openings, has characteristics of poor torsional rigidity, strong coupling of horizontal-torsional modes and significant discontinuity in the longitudinal variation of hull sections. In the mathematical formulation of the problem the hull is modeled as a beam and the transfer matrix method is utilized. The cross decks between cargo hatch opening are separated from the main hull and regarded as equivalent springs restraining torsion of hull. The effect of shear deformation of ship-side plating on torsion is taken into account in addition to St. Venant's and bending torsional rigidities. Compatibility requirements at cross section discontinuity are approximately considered. Developing the practical calculation procedure and the computer programs for application to an actual ship, some parametric studies on modeling methods of the cross deck, the compatibility condition, added-mass center etc. are out for the purpose of comparison.

• International Journal of Railway
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• v.3 no.4
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• pp.126-133
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• 2010

The thermal buckling analysis of curved continuous welded rail (CWR) is studied for the lateral buckling prevention. This study includes a thermal buckling theory which accounts for both thermal and vehicle loading effects in the evaluation of track stability. The parameters include rail size, track lateral resistance, track longitudinal and torsional stiffnesses, initial misalignment amplitude and wavelength, track curvature, tie-ballast friction coefficient and truck center spacing. Parametric studies are performed to evaluate the effects of the individual parameters on the upper and lower critical buckling temperatures. The results show that the upper critical buckling temperature is highly affected by the uplift due to vehicle loads. This study provides a guideline for the improvement of stability for dynamic buckling in curved CWR track.

• Research in Community and Public Health Nursing
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• v.17 no.3
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• pp.346-353
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• 2006

Purpose: The Purpose of this study was to analyze factors influencing the dependence of the elderly. Method: This research was designed as a descriptive study. The subjects were 103 elders living in Seoul. Data were collected from December 2004 through January 2005. The instrument used in this study was the elderly dependence scale developed by the Park (2004). Collected data were analyzed using SPSS 11.0 for Windows. Descriptive statistics, independent t-test, ANOVA and multiple regression were done. Results: In the results of regression, residence, education, vision and age were extracted as factors influencing the dependence of the elderly. The regression model explained 33% of the variance. Conclusion: Considering the results above, we need studies on the dependence of the elderly using more independent variables, on the changing pattern of dependence and influencing factors by longitudinal design, and on the elderly with functional limitations or cognitive impairment.

• Journal of the Korean Data and Information Science Society
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• v.25 no.5
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• pp.1117-1125
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• 2014

In a longitudinal study, subjects can experience same type of events repeatedly. Also, there may exist intermittent dropouts resulting in repeated observation gaps during which no recurrent events are observed. Furthermore, when such observation gaps have incomplete forms caused by the unknown termination times of observation gaps, ordinary approaches result in biased estimates. In this study, we investigate the effect of ignoring observation gaps and propose methods to overcome this problem. For estimating the distribution of unknown termination times, an interval-censored mechanism is applied and two cases are considered. Simulation studies are carried out to evaluate the performance of the proposed method. Conviction data of young drivers with several suspensions are analyzed to illustrate the suggested approach.

• Journal of Welding and Joining
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• v.31 no.6
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• pp.107-111
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• 2013

The welding distortion is caused by welding heat in the structures which are widely used in shipbuilding and automotive industries, thus many researchers have proposed such methods to control the welding distortion through trials and numerical studies. The welding distortion has been the main cause of low productivity due to the structural strength degradation, apparent flaw, additional deformation caused by the process followed the current assembly step, and the increase of correction workload. The deformation of fillet welding is investigated in this study, and the influence of the rib height on the welding distortion is verified through the actual experiment. And the numerical analysis model using the FE software MSC.marc for analysis of welding distortion is proposed.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.1
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• pp.41-49
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• 1998

A nonlinear mathematical model of longitudinal combustion instability appropriate for ramjets and augmenters was developed based on modal analysis. The model was limited to a two-mode formulation. The associated differential equations were solved both analytically and numerically. The two-mode nonlinear model is capable of predicting the bootstrapping effect which characterizes nonlinear velocity-sensitive combustion response. Also, parametric studies were performed.

• Journal of the Korea Society of Computer and Information
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• v.24 no.7
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• pp.135-141
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• 2019

The purpose of this study is to extract the key words from the list of research subjects related to 'hotel workers' published in recent 10 years(2009~2018) by using the language network analysis method and to confirm the relation between the key words. In this paper, we propose a semantic network analysis that can overcome limitations of longitudinal study, analyze the recent research trends, and widely use as a research model. The results of this study are as follows ; First, in analyzing major key words in the title of 'Hotel Employer' in recent 10 years, the major keyword of job satisfaction(40), special grade(26), organizational commitment(20), emotional labor(19), service(12), restaurant(10), and turnover intention(9). Second, we analyzed the relation of language network among major key words extracted from the study title of 'hotel workers'. Such a research process is expected to grasp the trends of research related to 'hotel workers' and give implications for the future direction of related research.

• Journal of the Korea Society of Computer and Information
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• v.23 no.11
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• pp.211-218
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• 2018

The purpose of the present study was to test the impact of depression on mobile phone dependency among elementary school students, to test the mediating effect of self-esteem between depression and mobile phone dependency, and to draw out theoretical and practical implications in terms of preventing or reducing mobile phone dependency. Based on previous studies, a longitudinal research model between the aforementioned three variables has been identified. The present study analyzed the 4th, 5th, and 6th wave data from Korea Children and Youth Panel Study 2010 (KCYPS 2010). The major results were as follows. First, depression could have a significant negative effect on self-esteem. Second, self-esteem could have a significant negative effect on mobile phone dependency. Third, the influence of depression on mobile phone dependency was not significant. Fourth, gender could be a significant moderating variable between depression and self-esteem. Finally, a number of implications of these findings were also discussed.

• Geomechanics and Engineering
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• v.16 no.6
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• pp.609-618
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• 2018

A new mechanical model for predicting the vibration of a pipe pile embedded in longitudinally layered visco-elastic media with radial inhomogeneity is proposed by extending Novak's plain-strain model and complex stiffness method to consider viscous-type damping. The analytical solutions for the dynamic impedance, the velocity admittance and the reflected signal of wave velocity at the pile head are also derived and subsequently verified by comparison with existing solutions. An extensive parametric analysis is further performed to examine the effects of shear modulus, viscous damping coefficient, coefficient of disturbance degree, weakening or strengthening range of surrounding soil and longitudinal soft or hard interbedded layer on the velocity admittance and the reflected signal of wave velocity at the pile head. It is demonstrated that the proposed model and the obtained solutions provide extensive possibilities for practical application compared with previous related studies.