• Coupled systems mechanics
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• v.4 no.1
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• pp.67-98
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• 2015

Numerical prediction of dynamic behavior of fully coupled saturated porous media is of great importance in many engineering problems. Specifically, static and dynamic response of soils - porous media with pores filled with fluid, such as air, water, etc. - can only be modeled properly using fully coupled approaches. Modeling and simulation of static and dynamic behavior of soils require significant Verification and Validation (V&V) procedures in order to build credibility and increase confidence in numerical results. By definition, Verification is essentially a mathematics issue and it provides evidence that the model is solved correctly, while Validation, being a physics issue, provides evidence that the right model is solved. This paper focuses on Verification procedure for fully coupled modeling and simulation of porous media. Therefore, a complete Solution Verification suite has been developed consisting of analytical solutions for both static and dynamic problems of porous media, in time domain. Verification for fully coupled modeling and simulation of porous media has been performed through comparison of the numerical solutions with the analytical ones. Modeling and simulation is based on the so called, u-p-U formulation. Of particular interest are numerical dispersion effects which determine the level of numerical accuracy. These effects are investigated in detail, in an effort to suggest a compromise between numerical error and computational cost.

• Geomechanics and Engineering
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• v.10 no.6
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• pp.709-726
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• 2016

Corrugated-core sandwich panels are prevalent for many applications in industries. The researches performed with the aim of optimization of such structures in the literature have considered a deterministic approach. However, it is believed that deterministic optimum points may lead to high-risk designs instead of optimum ones. In this paper, an effort has been made to provide a reliable and robust design of corrugated-core sandwich structures through stochastic and probabilistic multi-objective optimization approach. The optimization is performed using a coupling between genetic algorithm (GA), Monte Carlo simulation (MCS) and finite element method (FEM). To this aim, Prob. Design module in ANSYS is employed and using a coupling between optimization codes in MATLAB and ANSYS, a connection has been made between numerical results and optimization process. Results in both cases of deterministic and probabilistic multi-objective optimizations are illustrated and compared together to gain a better understanding of the best sandwich panel design by taking into account reliability and robustness. Comparison of results with a similar deterministic optimization study demonstrated better reliability and robustness of optimum point of this study.

• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.4
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• pp.1-13
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• 1999

Previous research for visual assessment of streetscape employed static simulation methods to represent future landscape. However, streetscape is experienced sequentially, and thus dynamic simulations can be more effective. This study tried to adopt computer animation in the evaluation of streetscape, and examined its effects and possibilities. Three development scenarios for the redevelopment districts of Sokong-Ro and Banpo-Ro in Seoul were designed, and simulations were produced by three methods-photo-retouching, computer still image, and animation. A preference questionnaire was asked to 69 university students, and the effects of simulation methods on visual preference were examined. In addition, the frames of the animation were reclassed to identify the visibility of physical elements. The relationships between the visibility and visual preference were analyzed. The results showed that visual preference can be explained by three factors-Amenity, Tidiness, and Variousness-that account for 62.4% of the total variance, and the Amenity showed the highest proportion: 36.0%. Among the three simulation methods, animation showed the largest difference in preference for the most important factor(Amenity), and yielded the highest correlation between visibility of physical elements and Amenity. This result demonstrated that dynamic simulations can provide more accurate observation of visual changes, especially because the simulated landscape is experienced sequentially. The results also revealed that the sequential change in the visibility of physical elements can be examined easily and precisely by animation. This benefit of animation enables analysts to identify the points where the landscape varies the most, and thus visual preference should be evaluated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.6
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• pp.544-550
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• 2009

To analyze the threat decision performance of MWR(Missile Warning Radar) give analysis on condition that we decide the effective threat using the POC(Probability of Over Countermeasure)/PUC(Probability of Under Countermeasure). Thus, we execute the simulation using the Monte-Carlo method to analyze effect, but the execution time of simulation took longer than we expected. In this paper, the effect analysis is proposed using the probability model to reduce the execution time of simulation. We present the setting method of parameter for probability model and the effect analysis result of MWR using the simulation. Also, we present the comparison result of simulation execution time for Monte-Carlo and probability model.

• Journal of Korean Critical Care Nursing
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• v.6 no.2
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• pp.24-36
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• 2013

Propose: This study was to investigate the educational effect and retention of repeated simulation-based basic life support (BLS) training for nursing students. Methods: A comparison group design with pretest and posttest was used. A total of 35 nursing students (18 for the experimental group, 17 for the control group) participated in the study. A repeated simulationbased BLS training program which include a lecture, skills training, and two repeated sessions of simulation practice and debriefing was provided twice for experimental group. Knowledge, self-efficacy, and skill performance of cardiopulmonary resuscitation (CPR) were measured three times: at baseline, week 2, and week 6. Descriptive analysis, repeated measures ANOVA, and t-test were used for data analyses. Results: Knowledge, self-efficacy and skill performance of CPR were not significantly changed by group assignment, by the time, and interaction of group by time. Effectiveness of intervention was not maintained until Week 6. Conclusion: The results suggest that the timing of repeat education, total training time, and students' mastery of CPR performance should be considered when developing simulation-based programs to improve and maintain students' CPR knowledge, self-efficacy, and skill performance.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.11
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• pp.533-539
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• 2005

In the previous work, we performed the analysis of a tubular type moving-magnet linear oscillatory actuator (LOA) with cylindrical Halbach array by using 2-d analytical formulas and confirmed validity of analytical results by comparison of those with both finite element (FE) computation and experimental results. This paper deals with the dynamic characteristic analysis of the moving-magnet LOA with cylindrical Halbach array. Control parameters such as the thrust constant, the back-emf constant, resistance and inductance are obtained from both analytical and experimental results. And then, the dynamic simulation algorithm is established by the state and output equation obtained from voltage and motion equation. Finally, for various values of frequency, the dynamic simulation and experimental results for the characteristics of the voltage, current and displacement of moving-magnet LOA are presented. The simulation results are validated extensively by experiments. The experimental and simulation results for the variation of stroke according to control voltage are also presented for various values of frequency.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.4
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• pp.330-337
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• 2015

When a tower crane is carried by a transporter in shipyard, the height and length of the tower crane should be adjusted to meet the safety guidelines. Since the guidelines came from the field experience, the safety limitation needs to be analyzed by a computer simulation. In this paper, modeling methods are addressed to implement the appropriate transportation simulation of a tower crane. For the relation between the tower crane and the transporter, normal contact force, friction force, and kinematic constraints are compared. Assignment of relevant linear acceleration and angular velocity is considered for the transporter to start or move on an inclined ground surface. By using the examined modeling methods, the dynamic motion of tower crane transportation is analyzed by a dynamic simulation program, and comparison between the simulation result and analytic solution is made to verify the feasibility of the modeling methods.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.2
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• pp.91-97
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• 2012

This paper presents a state space model of a two quadrant chopper and PWM inverter-fed Interior Permanent Magnet Synchronous Motor (IPMSM) drive system and its application to hybrid vehicles. The drive system has two different state equations for motoring and regenerating action. This paper presents a common state equation by using State Space Averaging method. Using this model of the IPMSM drive system, detailed simulation and controller design of the drive system, including PWM inverter switching, are given. The validity of this model and usefulness, according to a comparison among Maximum Torque/Ampere control, Maximum Torque/Flux control, and Maximum Efficiency optimization, are confirmed from simulation results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.1
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• pp.152-157
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• 2003

Process design of hot forging, asymmetric to symmetric rib-web shape steel, which is used for the turnout of railway express has been investigated. Owing to the big difference in shape between the initial billet and the final forged product, it is impossible to hot forge the rail in a single step. Therefore, multi step forging as well as die design for each step are necessary for the production. The deformation behavior during hot forging has been analyzed by the numerical simulation through commercial FEA software, $DEFORM^{TM}$-2D. Modification of the design and repeated simulation have been carried out on the basis of the simulation result. For comparison with the simulation results. flow analysis experiment using plasticine has been also carried out. The results of the flow analysis experiment showed good agreement with those of the simulation. Therefore, the developed process design could be applied to the actual production.

• Korean Journal of Adult Nursing
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• v.27 no.2
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• pp.135-145
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• 2015

Purpose: The purpose of this study was to evaluate the effects of a colonoscopy simulation program on knowledge and clinical performance among nursing students. Methods: The program consisted of a scenario with three objectives: health assessment, nursing before/after colonoscopy and emergency care for bleeding following the colonoscopy. A nonequivalent control group pretest-posttest design was used. The sample was 149 nursing students recruited from H University in G city from August, 2013 to December, 2014. The treatment group (n=71) received the simulation and the comparison group (n=78) received the usual lecture program. Data were analyzed using descriptive statistics, ${\chi}^2$ test, t-test and repeated measure ANOVA using the SPSS/WIN 20.0 program. Result: Participants in the treatment group had significantly increased reported scores on both knowledge and clinical performance. Conclusion: Results indicate that the simulated program is a useful strategy for improving knowledge and clinical performance among nursing students. The development of simulation practice programs in a variety of fields are needed in order to promote the practical competence of nursing students.