• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.1
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• pp.192-210
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• 2024

Most frequency-domain remote sensing image watermarking algorithms embed watermarks at random locations, which have negative impact on the watermark invisibility. In this study, we propose an adaptive watermarking scheme for remote sensing images that considers the information complexity to select where to embed watermarks to improve watermark invisibility without affecting algorithm robustness. The scheme converts remote sensing images from RGB to YCbCr color space, performs two-level DWT on luminance Y, and selects the high frequency coefficient of the low frequency component (HH^Y₂) as the watermark embedding domain. To achieve adaptive embedding, HH^Y₂ is divided into several 8*8 blocks, the entropy of each sub-block is calculated, and the block with the maximum entropy is chosen as the watermark embedding location. During embedding phase, the watermark image is also decomposed by two-level DWT, and the resulting high frequency coefficient (HH^W₂) is then embedded into the block with maximum entropy using α- blending. The experimental results show that the watermarked remote sensing images have high fidelity, indicating good invisibility. Under varying degrees of geometric, cropping, filtering, and noise attacks, the proposed watermarking can always extract high identifiable watermark images. Moreover, it is extremely stable and impervious to attack intensity interference.

• International Journal of Reliability and Applications
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• v.2 no.3
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• pp.209-240
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• 2001

Computer-based simulation and analysis is used extensively in engineering for a variety of tasks. Despite the steady and continuing growth of computing power and speed, the computational cost of complex high-fidelity engineering analyses and simulations limit their use in important areas like design optimization and reliability analysis. Statistical approximation techniques such as design of experiments and response surface methodology are becoming widely used in engineering to minimize the computational expense of running such computer analyses and circumvent many of these limitations. In this paper, we compare and contrast five experimental design types and four approximation model types in terms of their capability to generate accurate approximations for two engineering applications with typical engineering behaviors and a wide range of nonlinearity. The first example involves the analysis of a two-member frame that has three input variables and three responses of interest. The second example simulates the roll-over potential of a semi-tractor-trailer for different combinations of input variables and braking and steering levels. Detailed error analysis reveals that uniform designs provide good sampling for generating accurate approximations using different sample sizes while kriging models provide accurate approximations that are robust for use with a variety of experimental designs and sample sizes.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.1
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• pp.113-120
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• 2016

This paper presents observer-based virtual sensors for YMC(Yaw Moment Control) systems by differential braking. A high-fidelity empirical model of the hydraulic unit in YMC system was developed for a model-based observer design. Optimal, adaptive, and robust observers were then developed and their estimation accuracy and robustness against model uncertainty were investigated via HILS tests. The HILS results indicate that the proposed disturbance attenuation approach indeed exhibits more satisfactory pressure estimation performance than the other approach with admissible degradation against the predefined model disturbance.

• Journal of computational fluids engineering
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• v.19 no.3
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• pp.1-7
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• 2014

One of the most important factors in sailing yacht design is an accurate velocity prediction. Velocity prediction programs (VPPs) are widely used to predict velocity of sailing yachts. VPPs, which are primarily based on experimental data and experience of long years, suffer limitations applied in realistic conditions. Thus, in the present study, a high fidelity velocity prediction method using the computational fluid dynamics (CFD) is proposed. Using the developed method, velocity and motion of a 30 feet sloop yacht, which was developed by Korea Research Institute of Ship and Ocean (KRISO) and termed KORDY30, were predicted in upwind sailing condition.

• The Journal of Korean Academic Society of Nursing Education
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• v.19 no.3
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• pp.307-319
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• 2013

Purpose: The purpose of this study was to review nursing studies with regard to simulation- based learning in Korea. Methods: This systematic review examines the literature on simulation in nursing education from 2003 to 2012. The electronic databases reviewed included: RISS, the National Assembly Library, the National Library of Korea, and major nursing journal databases in Korea. The MeSH search terms included nursing, simulation, simulator, and standardized patient. Results: In total, 52 studies were included in the literature review. We included 21 quasi-experimental studies and 25 studies using high-fidelity simulation. They included knowledge and problem-solving ability in the cognitive domain; self efficacy, learning satisfaction, interpersonal relationships and communication, and confidence in the affective domain; and clinical performance ability and learning performance evaluation in the psychomotor domain. This systematic literature review revealed that simulation is useful in nursing education but uncovered a gap in the literature pertaining to the transfer of knowledge to performance and how to learn from cognitive reflection. Conclusions: This result suggests that it is necessary to conduct additional research on the cognitive learning process and transition to performance.

• Women's Health Nursing
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• v.26 no.1
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• pp.61-71
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• 2020

Purpose: This study was conducted to investigate the effects of problem-based learning-integrative simulation practice (PBL-ISP) on nursing knowledge, critical thinking, problem-solving ability, and immersion among nursing students. Methods: The study used a nonequivalent control group post-test design. A PBL-ISP educational program was provided to the experimental group, and hands-on practice using a high-fidelity simulator (HFS) was administered to the control group. There were 42 subjects in the experimental group and 40 in the control group. Data were collected during the fall semester of 2019. Using SPSS for Windows version 23.0, data were analyzed in terms of frequency, percentage, mean, standard deviation, the chi-square test, t-test, and Pearson correlation coefficients. Results: Significant differences between the experimental and control groups were found in nursing knowledge (t=3.67, p<.001), critical thinking (t=3.40, p=.001), problem-solving ability (t=3.52, p=.001) and immersion (t=4.44, p<.001). Conclusion: PBL-ISP was more effective in improving nursing knowledge, critical thinking, problem-solving ability, and immersion than was hands-on practice using an HFS.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.5
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• pp.998-1013
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• 2013

Wireless wearable sensor networks have emerged as a promising technique for human motion tracking due to the flexibility and scalability. In such system several wireless sensor nodes being attached to human limb construct a wearable sensor network, where each sensor node including MEMS sensors (such as 3-axis accelerometer, 3-axis magnetometer and 3-axis gyroscope) monitors the limb orientation and transmits these information to the base station for reconstruction via low-power wireless communication technique. Due to the energy constraint, the high fidelity requirement for real time rendering of human motion and tiny operating system embedded in each sensor node adds more challenges for the system implementation. In this paper, we discuss such challenges and experiences in detail during the implementation of such system with wireless wearable sensor network which includes COTS wireless sensor nodes (Imote 2) and uses TinyOS 1.x in each sensor node. Since our system uses the COTS sensor nodes and popular tiny operating system, it might be helpful for further exploration in such field.

• Nuclear Engineering and Technology
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• v.52 no.9
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• pp.1896-1906
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• 2020

The BEAVRS (Benchmark for Evaluation and Validation of Reactor Simulation) benchmark calculations were performed by DeCART stand-alone and DeCART/MATRA multi-physics coupled code system to verify their accuracy. The solutions of DeCART stand-alone calculations for the control rod bank worth, detector signal, isothermal temperature coefficient, and critical boron concentration agreed very well with the measurements. The root-mean-square errors of the boron letdown curves for two-cycles were less than about 20 ppm, while the individual and total control rod bank worth agreed well within 7.3% and 2.4%, respectively. For the BEAVRS benchmark calculations at the beginning of burnup, the difference between DeCART simplified thermal-hydraulic stand-alone and DeCART/MATRA coupled calculations were not significantly large. Therefore, it is concluded that both the DeCART stand-alone code and the DeCART/MATRA multi-physics coupled code system have the capabilities to generate high fidelity transport solutions at core follow calculations.

• Culinary science and hospitality research
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• v.24 no.3
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• pp.60-70
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• 2018

Rapid economic growth brought material affluence and convenience, but it also has caused a negative issue, such as environmental damage. Therefore, this research holds the purpose of grasping structural influencing relationship of environmental awareness of cook, which is taking an important role in food safety among workers in hotel restaurants with eco-friendly attitude and food safety pursuit behavior. To achieve the purpose, collected materials were tested for the fidelity, organic causation and control effect, using Structural Equation Modeling for frequency analysis, confirmatory factor analysis, credibility analysis and hypothesis testing with SPSS (V23.0) and AMOS (V21.0) programs. Environmental awareness of hotel cook has causation with eco-friendly attitude, and the attitude has meaningful causation with food safety pursuit behavior. That is, it proved that cooks are taking care of their job carefully from the pre-cooking stage while most of people ignore the storing stage. The result shows not only hotel's own training session, cook's level of consciousness on the food safety and they are working with high sense of responsibility. The limitation of this research is that it only conducted with cooks of deluxe hotels in Busan, and it could not include various variables about environmental awareness. Therefore, it is expected that the lacking contents to be dealt by a follow-up study.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.12
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• pp.1152-1162
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• 2008

This paper deals with the State-Dependent Riccati Equation (SDRE) technique for the design of helicopter nonlinear flight controllers. Since the SDRE controller requires a linear system-like structure for nonlinear motion equations, a state-dependent coefficient (SDC) factorization technique is developed in order to derive the conforming structure from a general nonlinear helicopter dynamic model. Also on-line numerical methods of solving the algebraic Riccati equation are investigated to improve the numerical efficiency in designing the SDRE controllers. The proposed method is applied to trajectory tracking problems of the helicopter and computational tips for a real time application are proposed using a high fidelity rotorcraft mathematical model.