• Journal of Astronomy and Space Sciences
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• 제26권4호
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• pp.651-658
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• 2009

Nonlinear sliding surface design in variable structure systems for spacecraft attitude control problems is studied. A robustness analysis is performed for regular form of system, and calculation of actuator bandwidth is presented by reviewing sliding surface dynamics. To achieve non-singular attitude description and minimal parameterization, spacecraft attitude control problems are considered based on modified Rodrigues parameters (MRP). It is shown that the derived controller ensures the sliding motion in pre-determined region irrespective of unmodeled effects and disturbances.

• Steel and Composite Structures
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• 제18권3호
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• pp.711-737
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• 2015

Steel Plate Shear Walls (SPSWs) have been accepted widely as an effective lateral load resisting system. For seismic performance evaluation of a multi-story building with SPSWs, detailed finite element models or a strip model can be used to represent the SPSW components. However, such models often require significant effort for tall or medium height buildings. In order to simplify the analysis process, discrete elements for the framing members can be used. This paper presents development of a simplified equivalent braced model to study the behavior of the SPSWs. The proposed model is expected to facilitate a simplification to the structural modeling of large buildings with SPSWs in order to evaluate the seismic performance using regular structural analysis tools. It is observed that the proposed model can capture the global behavior of the structures quite accurately and potentially aid in the performance-based seismic design of SPSW buildings.

• Ocean Systems Engineering
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• 제2권4호
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• pp.239-255
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• 2012

Analysis of ship parametric roll has generally been restricted to simple analytical models and sophisticated time domain simulations. Simple analytical models do not capture all the critical dynamics while time-domain simulations are often time consuming to implement. The model presented in this paper captures the essential dynamics of the system without over simplification. This work incorporates various important aspects of the system and assesses the significance of including or ignoring these aspects. Special consideration is given to the fact that a hull form asymmetric about the design waterline would not lead to a perfectly harmonic variation in metacentric height. Many of the previous works on parametric roll make the assumption of linearized and harmonic behaviour of the time-varying restoring arm or metacentric height. This assumption enables modelling the roll motion as a Mathieu equation. This paper provides a critical assessment of this assumption and suggests modelling the roll motion as a Hills equation. Also the effects of non-linear damping are included to evaluate its effect on the bounded parametric roll amplitude in a simplified manner.

• International Journal of Aerospace System Engineering
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• 제7권2호
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• pp.6-12
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• 2020

The precise prediction of future position of satellite depends on the accurate determination of orbit, which is also helpful in performing orbit maneuvers and trajectory correction maneuvers. For estimating the orbit of satellite many methods are being used. Some of the conventional methods are based on (i) Differential Correction (DC) (ii) Extended Kalman Filter (EKF). In this paper, Differential Evolution (DE) is used to determine the orbit. Orbit Determination using DC and EKF requires some initial guess of the state vector to initiate the algorithm, whereas DE does not require an initial guess since a wide range of bounds for the design unknown variables (orbital elements) is sufficient. This technique is uniformly valid for all orbits viz. circular, elliptic or hyperbolic. Simulated observations have been used to demonstrate the performance of the method. The observations are generated by including random noise. The simulation model that generates the observations includes the perturbation due to non-spherical earth up to second zonal harmonic term.

• 한국의류학회지
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• 제37권4호
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• pp.577-589
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• 2013

Fashion is traditionally perceived as a non-art in art philosophy; however, it is now being evaluated as art through the process of recognizing its cultural value and position. This study investigated the expanded concept of contemporary fashion in the same context of the expanded concept of contemporary art to present the possibility of fashion as art. This study enhances the artistic and cultural value, as well as the social function and position, of fashion by granting it the same status as art according to the concept of expanded contemporary art. For the research method, a literature review and a case analysis were conducted through specialty publications related to art history, aesthetics, and fashion in addition to regular publications, websites specializing in fashion, art museums and fashion style websites. The expanded aesthetic concept of contemporary art has embraced challenges to ideal beauty, production methods through interactivity, and expansion of art expression through mass media and industrial products. In the same context, the expanded aesthetic concept of contemporary fashion has established challenges to conventional beauty, the expansion of production methods, and the expansion and transfiguration of materials.

• Earthquakes and Structures
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• 제18권2호
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• pp.263-273
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• 2020

The use of energy concepts in seismic analysis and design of structures requires the understanding of the input energy response of multi-degree-of-freedom (MDOF) systems subjected to strong ground motions. For design purposes and non-time consuming analysis, however, it would be beneficial to associate the input energy response of MDOF systems with those of single-degree-of-freedom (SDOF) systems. In this paper, the theoretical formulation of energy input to MDOF systems is developed on the basis that only a particular portion of the total mass distributed among floor levels is effective in the nth-mode response. The input energy response histories of several reinforced concrete frames subjected to a set of eleven horizontal acceleration histories selected from actual recorded events and scaled in time domain are obtained. The contribution of the fundamental mode to the total input energy response of MDOF frames is demonstrated both graphically and numerically. The input energy of the fundamental mode is found to be a good indicator of the total energy input to two-dimensional regular MDOF structures. The numerical results computed by the proposed formulation are verified with relative input energy time histories directly computed from linear time history analysis. Finally, the elastic input energies are compared with those computed from time history analysis of nonlinear MDOF systems.

• 대한간호학회지
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• 제44권2호
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• pp.189-197
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• 2014

Purpose: This study was conducted to develop an asthma management education program for preschool children using Roy's adaptation theory as a framework and examining the effects of this program on adaptation to asthma treatment. Methods: A non-equivalent control group pre-post-test design was used with 43 preschool children diagnosed with asthma and required to be hospitalized for inhalation therapy. An intervention group (n=23) participated in the educational program and a control group (n=20) received regular treatment. The education program was conducted and evaluated from June 30 to October 31 2012, a maximum 3 times every 24 hours during hospitalization. Two nurses conducted the program using the teaching method of Gagn$\acute{e}$ and Briggs; instruction design theory through questionnaires to measure perception of disease, behavior of adaptation to treatment with inhalation therapy. Results: Effects of asthma management education program; scores for face-pain rating decreased and time of adaptation to treatment increased significantly in the experimental group compared to the control group but no significant differences were found for perception of the disease's cause and treatment. Conclusion: Results indicate that the asthma management education program has positive effects on adaptation to asthma treatment of preschoolers.

• 동서간호학연구지
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• 제17권1호
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• pp.16-23
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• 2011

Purpose: As anger may be strongly related to stroke, this study examined the relationship between anger expression style (anger-in, anger-out, anger-control) and risk factors for stroke to investigate the possible attribution of anger expression style to stroke incidence. Methods: The cross sectional study design was employed. The 291 participants signed consent forms and completed questionnaires including the anger expression style scales and risk factors for stroke. Data were analyzed using descriptive statistics, t-test and One-way ANOVA. Results: The highest score among anger expression styles of the participants was from anger-control. Participants with higher mean value of anger-out were current non-smokers, doing regular exercise, having scores above 23 in Body Mass Index, having scores above 90 cm (male) or 80 cm (female) in abdominal circumference, and having scores below 85 mmHg in diastolic blood pressure. Participants with more than 5 risk factors to stroke had the highest score of anger-in. Conclusion: The results of this study implied anger expression style was psychological risk factor for stroke. Further studies to differentiate the anger expression style contributing to the risk of stroke are needed with a longitudinal study design.

• 한국의류학회지
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• 제26권9호
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• pp.1342-1353
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• 2002

The purpose of this study was to provide the basic information to be helpful in establishing more rational prices discount strategy in prices discount advertising. The experiment design for study was a $3{\times}2{\times}3$ between subject factorial design in which the factors were discount presentation types(discount price presentation/discount rate presentation/discount price and discount rate presentation), existence of normal price presentation(presentation/ non-presentation) and semantic cues(regular sales/markdown on the previous season's product/storehouse opening sales). Thirty subjects were randomized in one of 18 experimental conditions. The subjects of this study were 540 female university students in Kwangju, Korea. The results were as follows; 1. Significant interaction effects between discount presentation types and the semantic cues were found in perceived transaction value(p<.01), perceived acquisition value(p<.05), and purchase intention(p<.05)- It means that discount presentation types in prices discount advertising need to present differently according to price discount types. 2. Significant interaction effects between existence of normal price and the semantic cues were not found. It means that normal price need to present in prices discount advertising regardless of price discount types.

• Steel and Composite Structures
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• 제5권2_3호
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• pp.181-192
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• 2005

The effective length method for flexural (column) buckling has been used for many decades but its use is somewhat limited in various contemporary design codes to moderately slender structures with elastic critical load factor (${\lambda}_{cr}$) less than 3 to 5. In pace with the use of higher grade steel in recent years, the influence of buckling in axial buckling resistance of a column becomes more important and the over-simplified assumption of effective length factor can lead to an unsafe, an uneconomical or a both unsafe and uneconomical solution when some members are over-designed while key elements are under-designed. Effective length should not normally be taken as the distance between nodes multiplied by an arbitrary factor like 0.85, 1.0, 2.0 etc. Further, the classification of non-sway and sway-sensitive frames makes the conventional design procedure tedious to use and, more importantly, limited to simple regular frames. This paper describes the practical use of second-order analysis with section capacity check allowing for $P-{\delta}$ and $P-{\Delta}$ effects together with member and system imperfections. Most commercial software considers only the $P-{\Delta}$ effect, but not member and frame imperfections nor $P-{\delta}$ effect, and engineers must be very careful in their uses. A verification problem is also given for validation of software for this type of powerful second-order analysis and design. It is a trend for popular and advanced national design codes in using the second-order analysis as a norm for analysis and design of steel structures while linear analysis may only be used in very simple structures.