• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.3
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• pp.97-103
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• 2004

Most of the columns in centrally braced steel frame buildings are usually designed as the gravity columns to reduce connection cost. For a rational seismic performance evaluation of centrally braced steel frame buildings, it is important to properly incorporate in the analysis  the P-${\Delta}$ effects arising from the gravity columns. An effective scheme for the P-${\Delta}$ effects modeling due to the gravity columns was illustrated based on the concept of fictitious leaning column. Seismic performance evaluation of inverted V braced steel frames with or without P-${\Delta}$ effects modeling was conducted by following the FEMA 273 NSP (Nonlinear Static Procedure). The problem in estimating dynamic P-${\Delta}$ modification factor (C3) in FEMA 273 was discussed. The results of this study indicated that the P-${\Delta}$ effects should be included in the seismic performance evaluation of centrally braced steel frames. This study also showed that the inverted V braced frames, retrofitted by applying the tie bars to redistribute the inelastic demand over the height of the building, exhibit significantly improved seismic performance.

• Journal of the Ergonomics Society of Korea
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• v.29 no.6
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• pp.907-914
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• 2010

Cognitive model, that is cognitive architecture, is the model expressed with computer program to show the process how human solve a certain problem and it is continuously under investigation through various fields of study such as cognitive engineering, computer engineering, and cognitive psychology. In addition, the much extensive applicability of cognitive model usually helps it to be used for quantitative prediction of human Behavior or Natural programming of human performance in many HCI areas including User Interface Usability, artificial intelligence, natural programming language and also Robot engineering. Meanwhile, when a system designed, an usability test about conceptual design of interface is needed and in this case, analysis evaluation using cognitive model like GOMS or ACT-R is much more effective than empirical evaluation which naturally needs products and subjects. In particular, if we consider the recent trend of very short-end term between a previous technology development and the next new one, it would take time and much efforts to choose subjects and train them in order to conduct usability test which is repeatedly followed in the process of a system development and this finally would bring delays of development of a new system. In this study, we predicted quantitatively the human behavior processes which contains cognitive processes for menu selection in touch screen interface through ACT-R, one of the common method of usability test. Throughout the study, it was shown that the result using cognitive model was equal with the result using existing empirical evaluation. And it is expected that cognitive model has a possibility not only to be used as an effective methodology for evaluation of HCI products or system but also to contribute the activation of HCI cognitive modeling in Korea.

• Fashion & Textile Research Journal
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• v.8 no.1
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• pp.25-33
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• 2006

As the cultures of the world are getting diverse and plural, many trials to find their own unique culture of their own national and racial characteristics are made where fashion and traditional culture is used as good materials; in Korea, this trend is also studied by many authors. To achieve this goal, this study recognized the importance of tourism industry by inviting hosting of international event like '2005 APEC Summit Conference and Economical Ministers' Conference', and invented a uniform design that can make identification in the world market including Korea 'Gust' and 'Emotion' in developing uniforms for employees of regular traditional restaurant or hotels that contribute to tourism industry. As a material of this study from this perspective, Soo Bok pattern among many other Korean traditional patterns were chosen, and used them to design uniforms by applying diverse expressions methods through modernization task. This study tried to suggest ideas in creating new designs with a modeling sense of our people, by emphasizing on tradition motive through analysis of conditions and problem regarding the current uniforms worn in traditional restaurants. The development of uniform that modernly reinterprets traditional patterns and design that uses tradition on modern design shows endless possibility of development of our uniform, and even shows the possibility of mixture between tradition and modernity. By applying traditional beauty not only in traditional restaurants but also in many places and businesses that foreigners frequently visit can allow to spread the excellency our culture; and the Korean uniform can be successful in the international market as Korean will have pride in our tradition by wearing this new uniform.

• The Korean Journal of Community Living Science
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• v.22 no.3
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• pp.341-349
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• 2011

As elder abuse has become a social problem, it has drawn a great deal of attention from researchers and policy-planers. While there have been a number of studies addressing various issues related to elder abuse, the present study aims to explain whether and how the perception of elder abuse would differ among the elderly themselves. In particular, the study focuses on the differences between urban and rural areas. Family-centered culture is believed to have a stronger influence in rural areas compared to urban areas. This cultural tradition highlights the importancy of the family compared to the individuals. Thus, the elderly who experience abuse would take it as personal matter rather than publicizing it. In addition, the information and campaigns on preventing elder abuse are less prevalent in rural areas than in urban areas due to limited communication networks. For these reasons, the study suggests a hypothesis that the elderly in rural areas are less perceptive to elder abuse. Using 6,709 persons aged 65 and over from a nationwide survey conducted by the Korean Institute for Health and Social Affairs in 2009, the study ran regression analysis on 4 types of elder abuse including psychological, financial, physical and neglect. The results show that regardless of types of abuse, the elderly in rural areas have lower levels of perception than the elderly in urban areas do. In addition, the frequency of social activities is positively related to the perception of elderly abuse. This is also true for the different types of elder abuse. The findings suggest that social effort to prevent elder abuse consider the urban-rural differences and their sources.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.729-732
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• 2010

The present study has been motivated by the development of a reliable numerical methodology for simulation of kerosene/LOx coaxial swirl injectors. To deal with thermodynamic non-ideality and anomalies of transport properties pronounced at supercritical pressures, a set of subroutine libraries has been constructed based on the cubic equations of state, and applied to an existing flamelet analysis code. For computational efficiency, two-dimensional axisymmetric RANS formulation with swirl was adopted and validated successfully against an isothermal coaxial swirling jet. For the actual problem with high pressure combustion, however, numerical results show that the RANS models yield excessive production of turbulence probably due to high density gradient magnitude in the vicinity of mixing layer of swirling film flow, and imply strongly further improvement of the turbulence models.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.820-824
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• 2010

The purpose of this study is to develop basic technology of hybrid rocket vehicle by constructed and launched. This small hybrid rocket using HDPE/LN2O and Aluminium steel for its body (weight : 12.5 kg, diameter : 114 mm, height : 1.8 m) was designed. The fuel grain and injector were designed for 50 kgf thrust and burning time 2.5 sec. This rocket was loaded the data acquisition device for obtaining data of pressure and velocity during its flying and equiped an automatic ejector system using spring/motor and timer to collect the rocket more safely after launching. It was launched successfully, but found some problem that the rocket's weight was heavier than expected and the thrust was not enough to reach the designed altitude and analyzed its flight path way.

• Structural Engineering and Mechanics
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• v.54 no.5
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• pp.855-875
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• 2015

Many novel materials exhibit a property of different elastic moduli in tension and compression. One such material is graphene, a wonder material, which has the highest strength yet measured. Investigations on buckling problems for structures with different moduli are scarce. To address this new problem, firstly, the nondimensional expression of the relation between offset of neutral axis and deflection curve is derived based on the phased integration method, and then using the energy method, load-deflection relation of the rod is determined; Secondly, based on the improved constitutive model for different moduli, large deformation finite element formulations are developed and combined with the arc-length method, finite element iterative program for rods with different moduli is established to obtain buckling critical loads; Thirdly, material mechanical properties tests of graphite, which is the raw material of graphene, are performed to measure the tensile and compressive elastic moduli, moreover, buckling tests are also conducted to investigate the buckling behavior of this kind of graphite rod. By comparing the calculation results of the energy method and finite element method with those of laboratory tests, the analytical model and finite element numerical model are demonstrated to be accurate and reliable. The results show that it may lead to unsafe results if the classic theory was still adopted to determine the buckling loads of those rods composed of a material having different moduli. The proposed models could provide a novel approach for further investigation of non-linear mechanical behavior for other structures with different moduli.

• Structural Engineering and Mechanics
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• v.66 no.3
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• pp.317-328
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• 2018

In this paper, a new refined quasi-three-dimensional (3D) shear deformation theory for the bending analysis of functionally graded plate is presented. The number of unknown functions involved in this theory is only four against five or more in the case of the other shear and normal deformation theories. Due to its quasi-3D nature, the stretching effect is taken into account in the formulation of governing equations. In addition, the effect of different micromechanical models on the bending response of these plates is studied. Various micromechanical models are used to evaluate the mechanical characteristics of the FG plates whose properties vary continuously across the thickness according to a simple power law. The present theory accounts for both shear deformation and thickness stretching effects by a parabolic variation of displacements across the thickness, and the zero traction boundary conditions on the top and bottom surfaces of the plate without using shear correction factors. The problem is solved for a plate simply supported on its edges and the Navier solution is used. The results of the present method are compared with others from the literature where a good agreement has been found. A detailed parametric study is presented to show the effect of different micromechanical models on the flexural response of a simply supported FG plates.

• Structural Monitoring and Maintenance
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• v.6 no.4
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• pp.317-346
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• 2019

Performance assessment of pavements proves useful, in terms of handling the ride quality, controlling the travel time of vehicles and adequate maintenance of pavements. Roughness profiles provide a good measure of the deteriorating condition of the pavement. For the accurate estimates of pavement roughness from dynamic vehicle responses, vehicle parameters should be known accurately. Information on vehicle parameters is uncertain, due to the wear and tear over time. Hence, condition monitoring of pavement requires the identification of pavement roughness along with vehicle parameters. The present study proposes a scheme which estimates the roughness profile of the pavement with the use of accurate estimates of vehicle parameters computed in parallel. Pavement model used in this study is a two-layer Euler-Bernoulli beam resting on a nonlinear Pasternak foundation. The asphalt topping of the pavement in the top layer is modeled as viscoelastic, and the base course bottom layer is modeled as elastic. The viscoelastic response of the top layer is modeled with the help of the Burgers model. The vehicle model considered in this study is a half car model, fitted with accelerometers at specified points. The identification of the coupled system of vehicle-pavement interaction employs a coupled scheme of an unbiased minimum variance estimator and an optimization scheme. The partitioning of observed noisy quantities to be used in the two schemes is investigated in detail before the analysis. The unbiased minimum variance estimator (MVE) make use of a linear state-space formulation including roughness, to overcome the linearization difficulties as in conventional nonlinear filters. MVE gives estimates for the unknown input and fed into the optimization scheme to yield estimates of vehicle parameters. The issue of ill-posedness of the problem is dealt with by introducing a regularization equivalent term in the objective function, specifically where a large number of parameters are to be estimated. Effect of different objective functions is also studied. The outcome of this research is an overall measure of pavement condition.

• Korean Medical Education Review
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• v.20 no.1
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• pp.44-50
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• 2018

The purpose of this study was to investigate factors associated with the critical thinking ability of nursing students at the individual and school levels. The study adopted a descriptive design and recruited 465 nursing students from four nursing schools from November 2014 to September 2015 through convenience sampling. The Clinical Critical Thinking Skill Test was used to measure critical thinking ability, and the data were analyzed with the SAS ver. 9.4 program (SAS Institute Inc., Cary, NC, USA) for descriptive statistics, t-test, analysis of variance, and multi-level model. The results showed that clinical practicum experience (${\beta}=-0.72$, p=0.025), taking critical thinking courses (${\beta}=0.63$, p=0.010), and taking simulation courses (${\beta}=0.56$, p=0.035) improved critical thinking ability in the individual level model. In the school level model, the interaction effect between the years of clinical practice done by the student and the presence of full-time clinical instructors was significant (${\beta}=1.29$, p=0.011). These results suggest that critical thinking ability improves with the more years of clinical practice individual nursing students have, and this improvement is greater with the presence of full-time clinical instructors in the school. Therefore, it is recommended that nursing students undergo critical thinking and simulation courses to develop their critical thinking ability, and dedicated clinical instructors in nursing schools should play a vital role.