• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.9
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• pp.859-866
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• 2008

A guidance scheme for controlling the relative geometry of multiple flight vehicle formation flying is proposed. Each flight vehicle in the formation takes the roles of leader and follower simultaneously except for the formation leader. In this scheme, the flight commands for a leader are shared by all the followers and this leaders to a synchronized flight of all flight vehicles comprising the formation. Lyapunov stability theorem is used to obtain the guidance law. High fidelity nonlinear simulation results are presented to show the effectiveness of the proposed guidance law using a reconnaissance and surveillance mission example.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.5
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• pp.1017-1022
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• 2011

This paper describes the improvement of the calculation by using $6{\sigma}$ method on steam turbine simulator in a nuclear power plant. The simulator is essential to not only verification and validation of control logic but also making sure of control constants in upgrading the long time used control system into the new one. And the dynamic model is a key point in that simulator. The model used during the retrofit period of the turbine controller in Kori Nuclear Power Plant makes difference in calculating generator output and control valve positions. That is because such operating data as the main steam pressure, the main steam temperature and control valve positions of Yongkwang #3 are different from those of Kori #4. Therefore, the model parameters must be tuned by using actual operating data for the high fidelity of simulator in calculating the dynamic characteristic of the model. This paper describes that the $6{\sigma}$ method is used in improvement of precision of generator output calculation in the steam turbine model of the simulator.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.7
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• pp.2548-2567
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• 2015

Recently, there has been a clear trend towards the application of ad hoc networking technology in civil aviation communication systems, giving birth to a new research field, namely, aeronautical ad hoc networks (AANETs). An AANET is a special type of ad hoc wireless network with a significantly larger scale and distinct characteristics of its mobile nodes. Thus, there is an urgent need to develop a simulator to facilitate the research in these networks. In this paper, we present a network simulator, Aero-Sim, for AANETs. Aero-Sim, which is based on the freely distributed NS-2 simulator, enables detailed packet-level simulations of protocols at the MAC, link, network, transport, and application layers by composing simulations with existing modules and protocols in NS-2. Moreover, Aero-Sim supports three-dimensional network deployment. Through several case studies using realistic China domestic air traffic, we show that the proposed simulator can be used to simulate AANETs and can reproduce the real world with high fidelity.

• Journal of the Korean Society of Systems Engineering
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• v.12 no.2
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• pp.81-90
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• 2016

The system performance of Engineered Safety Features is of utmost importance in a nuclear power plant. The human performance is identified as most critical to assurance of the optimal operability of safety systems during an emergency. The aim of this study is to determine how the performance of safety system could be evaluated using Augmented Reality technology. The paper presents a description of how a systems engineered approach could be used to develop the necessary operating conditions needed to conduct this measurement. Augmented Virtual Reality (AVR) interface technology is achieving ease of availability and widespread use in many applications today as illustrated by the launch of several AR and VR devices aimed at media consumption. As such, environments that incorporate such AVR hardware have become invaluable tools in designing human interface systems because of the high fidelity and intuitive response to natural human interaction that can be achieved [2]. The outcome of the measurement undertaken is to determine whether 1.) Operator(s) performance can be enhanced by introducing an improved cognitive method of monitoring plant information during an Emergency Operating Procedures (EOP) and 2.) In correlation, inform the performance of the diverse safety systems on the basis of human factors.

• The Journal of Korea Robotics Society
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• v.8 no.3
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• pp.173-178
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• 2013

We present six-degree-of-freedom (6DoF) haptic rendering algorithms using translational ($PD_t$) and generalized penetration depth ($PD_g$). Our rendering algorithm can handle any type of object/object haptic interaction using penalty-based response and makes no assumption about the underlying geometry and topology. Moreover, our rendering algorithm can effectively deal with multiple contacts. Our penetration depth algorithms for $PD_t$ and $PD_g$ are based on a contact-space projection technique combined with iterative, local optimization on the contact-space. We circumvent the local minima problem, imposed by the local optimization, using motion coherence present in the haptic simulation. Our experimental results show that our methods can produce high-fidelity force feedback for general polygonal models consisting of tens of thousands of triangles at near-haptic rates, and are successfully integrated into an off-the-shelf 6DoF haptic device. We also discuss the benefits of using different formulations of penetration depth in the context of 6DoF haptics.

• Journal of the Korean Society of Systems Engineering
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• v.6 no.1
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• pp.33-39
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• 2010

Anti-surface missiles have been the most dangerous threat to the surface ships, therefore analyzing the defense effectiveness of surface ships against diverse anti-surface missiles attack strategies is very important to evaluate and anticipate the naval combat ship's abilities in terms of AAW (Anti-Air Warfare). In this paper, we don't study on the defense effectiveness of a ship against a missile, but focus on the defense effectiveness for surface ships against multiple missiles specialized in strategies of anti-surface missiles; ripple fire attack and simultaneous time on target attack (STOT). So, we conduct a variety of monte-carlo simulations with high-fidelity simulators, analyze the measure of defense effectiveness for the key factors of strategies and evaluate the effects and possible interactions of several factors through the analysis of the design of experiment (DOE).

• Korean Journal of Optics and Photonics
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• v.18 no.5
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• pp.303-308
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• 2007

We report here on the application of a digital holographic microscope as a metrology tool for the inspection and the micro-topography reconstruction of different micro-structures of phase shift photo-mask (PSM). The lithography by phase shift photo-mask uses the interference and the pattern of the PSM is not imaged by general optical microscope. The technique allows us to obtain digitally a high-fidelity surface topography description of the phase shift photo-mask with only one hologram image acquisition, allowing us to have relatively simple and compact set-ups able to give quantitative information of PSM.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.4
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• pp.555-560
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• 2017

Currently, railway wireless communication systems adopt several communication schemes depending on the specific region. To increase data rate and achieve high fidelity in railway wireless communication systems, LTE-R scheme has been developed. In this paper, We introduce interoperability technology which converges several railway communication systems including LTE-R. First, we consider two interoperability methods and their standardization. Some empirical test results of interoperability technology are also introduced. It is expected to provide seamless and statable railway communication environments by applying interoperability technologies to railway wireless communication systems.

• Child Health Nursing Research
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• v.24 no.1
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• pp.27-36
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• 2018

Purpose: The purpose of this study was to develop a model for handoff education for nursing students based on simulation using video and to identify educational effects of a simulated situation in pediatric care units. Methods: Data were collected from May 1 to 30, 2016. Participants were 84 senior nursing students in Seoul (video group: 43, simulation group: 41). Both groups were given a lecture and pre-briefing on handoff education. The simulation group had nursing practice on resolving health issues for respiratory distress using a high-fidelity baby simulator. The video group watched a video recording of a scenario based simulation, and used a summarized handoff situation to practice patient handoff to another student. Results: There was no significant difference between the two groups for handoff self-confidence, problem solving ability, handoff competence (self-assessment of students), or learning satisfaction. Self-confidence increased significantly in both groups. Handoff competency evaluated by the instructor was higher in the video group compared to the simulation group (t=2.33, p=.022). Conclusion: Nursing student education for handoff practice utilizing a video in the pediatric unit was more cost effective. Therefore, it could be a useful educational method for students in learning patient handoff practices and helpful for related research.

• International Journal of Fluid Machinery and Systems
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• v.9 no.3
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• pp.265-276
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• 2016

Energy systems working coherently in different conditions may not have a specific design which can provide optimal performance. A system working for a longer period at lower efficiency implies higher energy consumption. In this effort, a methodology demonstrated by a jet pump design and optimization via numerical modeling for fluid dynamics and implementation of an evolutionary algorithm for the optimization shows a reduction in computational costs. The jet pump inherently has a low efficiency because of improper mixing of primary and secondary fluids, and multiple momentum and energy transfer phenomena associated with it. The high fidelity solutions were obtained through a validated numerical model to construct an approximate function through surrogate analysis. Pareto-optimal solutions for two objective functions, i.e., secondary fluid pressure head and primary fluid pressure-drop, were generated through a multi-objective genetic algorithm. For the jet pump geometry, a design space of several design variables was discretized using the Latin hypercube sampling method for the optimization. The performance analysis of the surrogate models shows that the combined surrogates perform better than a single surrogate and the optimized jet pump shows a higher performance. The approach can be implemented in other energy systems to find a better design.