• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.73-76
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• 2008

The damage of earthquakes have to achieve by probabilistic evaluation because of uncertainty of earthquake. Fragility analysis is a useful tool for predicting the probability of damage induced by the probable earthquake. This paper presents the probability of damage as a function of peak ground acceleration and estimates the probability of five damage levels for the pier of prestressed concrete (PSC) bridge subjected to given ground acceleration. At each 100 artificial earthquake motions were generated in terms of soil conditions, and nonlinear time domain analyses were performed for the damage states of the pier of PSC bridge structures. These damage states are described by displacement ductility result from seismic performance based on existing research results. Using the damage states and ground motion parameters, five fragility curves for the pier of PSC bridges with five types of dominant frequencies were constructed assuming a log-nomal distribution. It was found that there was a significant effect on the fragility curves due to the dominant frequencies.

• Journal of Korean Academy of Nursing Administration
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• v.3 no.2
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• pp.17-40
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• 1997

The purpose of this descriptive, correlational study was to identify, describe the patterns of nursing unit culture, nursing performance, job satisfaction and turnover intention in the hospital setting, and to analyze the relationships between nursing unit culture, nursing performance, job satisfaction and turnover intention among the characteristic of the subjects The subject consisted of 223 nurses who were employed in medical & surgical units of 3 different University hospitals in Seoul. Data collection was done in November, 1996 by means of questionnaire. The instruments used for this study were the questionnaire based on the Nursing unit cultural assessment tool developed by Coeling(1993), Nursing performance scale used by Yoon(1991), Job satisfaction scale developed by Slavitt, et al.(1978) and Turnover intention scale used by Lee(1995). The data were analyzed by percentage distribution. Pearson correlation coefficient and ANOVA. The summarized results were as follows: 1. There was significant differences in the nursing unit culture between individual cultural behavior and group cultural behavior. 2. There was positive correlation between nursing unit culture, nursing performance and job satisfaction. 3. There was negative correlation between nursing unit culture and turnover intention. 4. There was significant difference in nursing performance efficiency according to the age, educational level, professional carrier in the nursing unit, in the hospital. 5. There was significant difference in turnover intention according to the age, educational level. According to these results, the following implications can be made ; 1. It needs to study on the nursing unit culture in other size hospitals and compare them to these results. 2. It is necessary to assess nursing unit culture and endeaveor good climate for the nursing organizational outcomes and prepare the training course of leadership of nurse manager. 3. In nursing administration, there should be an emphasis on assessment of staff nurses' cultural behavior in case of nurses' orientation, allocation, recruitment, continuning education, so that staff nurses' performance and job satisfaction will be increased and trunover intention will be decreased.

• Convergence Security Journal
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• v.8 no.4
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• pp.73-80
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• 2008

In this paper, we developed a WMS (Warehouse Management System) Simulator. There is no Simulator that supports optimized design for Warehouse, consider goods which storage in warehouse and using RFID and USN based on cable wireless network. Also, there is no tool for monitoring which decides delivery time with information about temperature, humidity and illumination, after goods are stocked into warehouse. In this paper, WMS Simulator Implements function of drawing a blueprint. The Simulator that can analyze moving information of Palette with RFID tags and the change about temperature, humidity and illumination is developed in this paper. Inventory accuracy, space equipment practical use, and decreasing of picking time, faulty storage and product loss by product processing ability elevation are expected by designing the way of operating of warehouse for most suitable use of system in physical distribution through these treatise.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.3
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• pp.275-280
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• 2008

A technique for reliability-based design optimization(RBDO) is developed based on the Bayesian approach, which can deal with the epistemic uncertainty arising due to the limited number of data. Until recently, the conventional REDO was implemented mostly by assuming the uncertainty as aleatory which means the statistical properties are completely known. In practice, however, this is not the case due to the insufficient data for estimating the statistical information, which makes the existing RBDO methods less useful. In this study, a Bayesian reliability is introduced to take account of the epistemic uncertainty, which is defined as the lower confidence bound of the probability distribution of the original reliability. In this case, the Bayesian reliability requires double loop of the conventional reliability analyses, which can be computationally expensive. Kriging based dimension reduction method(KDRM), which is a new efficient tool for the reliability analysis, is employed to this end. The proposed method is illustrated using a couple of numerical examples.

• Smart Structures and Systems
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• v.26 no.3
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• pp.373-390
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• 2020

Hybrid simulation (HS) is a versatile tool for structural performance evaluation under dynamic loads. Although real structural responses are often multiple-directional owing to an eccentric mass/stiffness of the structure and/or excitations not along structural major axes, few HS in this field takes into account structural responses in multiple directions. Multi-directional loading is more challenging than uni-directional loading as there is a nonlinear transformation between actuator and specimen coordinate systems, increasing the difficulty of suppressing loading error. Moreover, redundant actuators may exist in multi-directional hybrid simulations of large-scale structures, which requires the loading strategy to contain ineffective loading of multiple actuators. To address these issues, lately a new strategy was conceived for accurate reproduction of desired displacements in bi-directional hybrid simulations (BHS), which is characterized in two features, i.e., iterative displacement command updating based on the Jacobian matrix considering nonlinear geometric relationships, and force-based control for compensating ineffective forces of redundant actuators. This paper performs performance validation and application of this new mixed loading strategy. In particular, virtual BHS considering linear and nonlinear specimen models, and the diversity of actuator properties were carried out. A validation test was implemented with a steel frame specimen. A real application of this strategy to BHS on a full-scale 2-story frame specimen was performed. Studies showed that this strategy exhibited excellent tracking performance for the measured displacements of the control point and remarkable compensation for ineffective forces of the redundant actuator. This strategy was demonstrated to be capable of accurately and effectively reproducing the desired displacements in large-scale BHS.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.2
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• pp.65-70
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• 2008

This study deals with the friction welding of SKH55 and SM45C; The friction time was variable conditions under the conditions of spindle revolution 2,000rpm, friction pressure of 190MPa, upset pressure of 270MPa and upset time of 2.0 seconds. Under these conditions, the microstructure of weld interface, tensile fracture surface and mechanical tests were studied, and so the results were as follows. 1. When the friction time is 1.0 seconds, the tensile strength of friction welds was 926MPa, which is around as much as 84% of the tensile strength of base metal(SKH55), the bending strength of friction welds was 1,542MPa, which is around as much as 80% of the bending strength of base metal(SKH55), the shear strength of friction welds was 519MPa, which is around as much as 70% of the shear strength of base metal(SKH55). 2 According to the hardness test, the hardness distribution of the weld interface was formed from 964Hv to 254Hv. HAZ(Heat Affected Zone) was formed from the weld interface to 1.5mm of SKH55 and 2mm of SM45C.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.561-566
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• 2008

The reciprocating compressor is widely used in the industry field, because it has simple principle and high efficiency. In this work, in order to improve design of discharge passage line in hydrogen compression system Numerical analysis was conducted. General information about an internal gas flow is presented by numerical analysis approach. Relating with hydrogen compressing system, which have an important role in hydrogen energy utilization, this should be a useful tool to observe the flow quickly and clearly. Flow characteristic analysis, including velocity, pressure and turbulence kinetic energy distribution of hydrogen gas going out from the cylinder to discharge-path line are presented in this paper. Discharge-passage model is designed based on real model of hydrogen compressor. Pressure boundary conditions are applied considering the real condition of operating system. The result shows velocity, pressure and turbulent kinetic energy are not distributed uniformly along the passage of the Hydrogen system. Path line or particles tracks help to demonstrate flow characteristics inside the passage. The existence of vortices and flow direction can be precisely predicted. Based on this result, the design improvement might be done.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.2
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• pp.109-127
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• 2011

Atmospheric aerosols, small particles in the atmosphere, are one of the important parameters in climate change and human health. Additionally, accurate estimates of aerosol species are increasingly important in environmental impact assessment studies. Recent advances in global satellite remote sensing provide powerful tool for air quality monitoring. This study explores the potential usage of satellite derived data such as atmospheric aerosols for air quality monitoring as well as climate change study. The objectives of this study is to understand the general features of the global distribution of type dependent aerosols. A detailed spatio-temporal variability of the each different satellite dataset shows the variation of the global zonal average and specific geographical regions where the strong emission sources are located. Especially, significantly large aerosol amounts are observed in Asia and Africa because of the desert dust storm, anthropogenic and biomass burning emissions.

• Aerospace Engineering and Technology
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• v.1 no.1
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• pp.8-27
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• 2002

In this study, the load analysis of a composite canard aircraft is performed numerically. Excel visual basic program for PC is used to calculate aerodynamic coefficients, loads and moments etc.. The basic data required for the load analysis such as aircraft configuration and dimension, parts and its weight and coordinate etc. are obtained from Catia modeling, measurement or material density. Aircraft weight, center of gravity, inertia moment, structural design speeds, wing load distribution, forces and moments are evaluated by using these data. V-n diagram is also represented for selecting critical loads applied to the wing and fuselage. The V-n diagram is investigated to decide the flight envelope of canard aircraft for design speed VA, VC, VD and load factor +3.8G, -1.52G at maximum weight of 2,573 lbs and sea level. In the future, the results of the wing and fuselage load analysis is to represented by using selected critical loads.

• The Journal of Society for e-Business Studies
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• v.14 no.3
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• pp.131-151
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• 2009

Natural interface is important to select and provide the services in ubiquitous smart space such as u-plant, u-distribution. Augmented Reality(AR) has recently begun to receive attention as a realization tool for natural interface. AR provides virtual object on real environment and it differs from virtual reality. When AR is used, it has advantage to provide information intuitively and collaboratively. However AR is rarely used in e-commerce domain of ubiquitous smart space, and it has limitation which predefined information and services provide in a static manner. Hence, the purpose of this paper is to propose a methodology of AR based e-commerce which provides personalized association service by considering user's dynamic context. To do so, association algorithm is developed based on Rescorla-Wagner model and Galton's free association test.