• International Journal of Aeronautical and Space Sciences
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• v.10 no.2
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• pp.125-133
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• 2009

To numerically simulate aerodynamics of rotor-airframe interaction in a rigorous manner, we need to solve the Navier-Stokes system for a rotor-airframe combination as a whole. This often imposes a serious computational burden since rotating blades and a stationary body have to be simultaneously dealt with. An efficient alternative is to adopt a momentum source method in which the action of rotor is approximated as momentum source over a rotor disc plane in a stationary computational domain. This makes the simulation much simpler. For unsteady simulation, the instantaneous momentum sources are assigned only to a portion of disk plane corresponding to blade passage. The momentum source is obtained by using blade element theory with dynamic inflow model. Computations are carried out for the simple rotor-airframe model (the Georgia Tech model) and the results of the simulation are compared with those of the full Navier-Stokes simulation with moving mesh system for rotor and with experimental data. It is shown that the present simulation yields results as good as those of the full Navier-Stokes simulation.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.5
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• pp.387-396
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• 2009

The life and performance of lithium battery are greatly influenced by the formation process which is essential in the process of manufacture. Charge/discharge system for the lithium battery are required for the formation process. To simulate such a system in a conventional method takes very long time and requires huge memory space to save data files. So the simulation may be impossible with a general-purpose PC. In this paper, the lithium battery is modelled to a resistor-capacitor serial circuit and the lithium battery charge/discharge system is analyzed and simulated by using state space averaging method. As a result, the simulation time is reduced dramatically and the simulation of the lithium battery charge/discharge system becomes possible on a general-purpose PC within 3 hours. Also, both the charge/discharge characteristics and the time required to charge/discharge of the lithium battery charge/discharge system can be observed. To verify the propriety of resistor-capacitor serial circuit modeling method for lithium battery and the validity of the analysis and simulation based on state space averaging, the lithium battery charge/discharge system is composed and experimentations are carried out.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.9 no.9
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• pp.1041-1048
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• 2019

Recently, social demands on atypical buildings and building spaces are increasing, and examples of atypical buildings are easily seen in major cities around the world. This study investigates the user behaviors in the typical atypical buildings currently constructed and analyzes the characteristics of human behavior in the atypical building space. Ultimately, this study aims to develop human behavior simulation technology for reviewing residential performance of atypical building space design, and the results of this study can be used for user behavior modeling and simulation technology development. This is because it is difficult to find an investigation or analysis of what behavioral characteristics occur in the atypical building space in previous studies. This study derives the characteristics of human behavior in the atypical architectural space that has been overlooked in the existing human behavior simulation tools. In other words, the site visits and surveys typical atypical buildings to investigate user behaviors in typical spaces and other atypical buildings.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.101-101
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• 2004

• Journal of Astronomy and Space Sciences
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• v.34 no.2
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• pp.139-151
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• 2017

This paper presents an overview of deep space orbit determination software (DSODS), as well as validation and verification results on its event prediction capabilities. DSODS was developed in the MATLAB object-oriented programming environment to support the Korea Pathfinder Lunar Orbiter (KPLO) mission. DSODS has three major capabilities: celestial event prediction for spacecraft, orbit determination with deep space network (DSN) tracking data, and DSN tracking data simulation. To achieve its functionality requirements, DSODS consists of four modules: orbit propagation (OP), event prediction (EP), data simulation (DS), and orbit determination (OD) modules. This paper explains the highest-level data flows between modules in event prediction, orbit determination, and tracking data simulation processes. Furthermore, to address the event prediction capability of DSODS, this paper introduces OP and EP modules. The role of the OP module is to handle time and coordinate system conversions, to propagate spacecraft trajectories, and to handle the ephemerides of spacecraft and celestial bodies. Currently, the OP module utilizes the General Mission Analysis Tool (GMAT) as a third-party software component for high-fidelity deep space propagation, as well as time and coordinate system conversions. The role of the EP module is to predict celestial events, including eclipses, and ground station visibilities, and this paper presents the functionality requirements of the EP module. The validation and verification results show that, for most cases, event prediction errors were less than 10 millisec when compared with flight proven mission analysis tools such as GMAT and Systems Tool Kit (STK). Thus, we conclude that DSODS is capable of predicting events for the KPLO in real mission applications.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1124-1130
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• 2015

Moisture and high temperature are the most important factors that lead to the ageing of oil-paper insulation, but the research about space charge characteristics of oil-paper insulation does not take the combined effect of ambient temperature, moisture and thermal ageing into account. The pulsed electroacoustic (PEA) method was used to investigate the influence of moisture and temperature on space charge characteristics of oil paper at different ageing stages. The results showed that moisture could speed up formation of space charge in oil paper when water concentration was low, but the formation was restrained if the water concentration was high. At the beginning of thermal ageing, heterogeneous charge accumulation had predominance, but it gradually changed to homogeneous charge injection with ageing. It was believed that moisture concentration could speed up ageing and enhance charge accumulation on one hand, and accelerate or slow down the establishment speed of space charge on the other hand, therefore, charge accumulation type changed with ageing. The more seriously the oil-paper insulation was thermally aged, the deeper the trap energy level was, hence more space charge was trapped, which could be speeded up by increasing the ageing temperature, but the effect of ambient temperature did not fit the Arrhenius law.

• Journal of the Korea Society for Simulation
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• v.22 no.3
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• pp.15-23
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• 2013

In general, simulation models are effectively used in the field of engineering design. The experiment with simulation models to obtain optimal design parameters, however, is a time-consuming task and requires a lot of resources. Hence, meta-models representing the relationships between input variables and performance measures are exploited to efficiently determine the value of design parameters. To construct a meta-model, a number of simulation executions with sample scenarios are required. The number and quality of sample scenarios determine not only the level of efficiency in constructing the meta-model but also accuracy of the model. Space-filling condition is regarded to be an important condition for the quality of scenarios. This paper proposes sample scenario generation methods based on space-filling measures such as maxmin, Audze-Eglais, and centered L2-discrepancy. The performance of these scenario generation methods are evaluated through experiments.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.3
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• pp.37-53
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• 2016

This paper deals with an optimal output control for Space Shuttle Main Engine (SSME), a liquid propellant rocket engine using a staged-combustion cycle. For this purpose, we modeled simplified mathematical model of SSME using each SSME component divided into 7 major categories and found trim points called Rated Propulsion Level (RPL). For design the closed-loop system of SSME, we designed optimal output feedback Linear Quadratic Regulation (LQR) control system using SSME linearized model under RPL 104% and demonstrated the performance of the controller through numerical simulation.

• Journal of the Korean housing association
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• v.25 no.1
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• pp.23-32
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• 2014

This research progressed space evaluation test with 3D simulation for exterior space of detached housing area among the Seoul spaces of child sex offense in 2010. Based on changing analysis on natural surveillance by spatial changes of each physical element, the purpose is to suggest effective construction planning measure for preventing child sex offense. The results of research are as follows. First, natural surveillance of space's height differences and width differences were compared and analyzed. As the result, footpath shows that stairs of slope didn't make lots of effects on visual block, not block of spatial moving, because of the difference of stair height. Also, in case of parking space, visual connection with footpath is expanded when designing pilotis rather than heightening floor height, so activities of exterior people could be seen more easily. Therefore, natural surveillance was higher. Second, natural surveillance of architectural elements by changes of footpath' width was compared and analyzed. As the result, openness of footpath should be secured rather than openness of architectural element. And, planning autonomy of architectural form could be more expanded when securing openness of footpath.

• Korean Institute of Interior Design Journal
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• v.14 no.3 s.50
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• pp.156-164
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• 2005

Like other countries undergoing the aging of the population, increases in the aged population have raised serious issues in Korea. The proportion of elderly will be foreseen over $14\%$ of population in 2019, over $20\%$ in 2026 in korea. Due to the rapid increasing in the aged population, it calls for social countermeasures urgently, And recent researches about attitude to the aged find out in general negative attitude to the aged of other generations. It is thought desirable that comprehension to the aged of the commonalty should be educated on the school basis or a variety of informal ways. The study aims to determine the space formation of the senior simulation center that suggest to be considered for the effective education and preparation for the aging of all social members, particularly for the younger generation. In such space formation, it is important to work out a plan of efficiency education according to the systematic environmental setting with a focus on the minimization of problematic behaviors and living disabilities of aging, as interactive experiences gain malfunctions by aging. This study is expected to promote a focus on the integration of the whole generations and improved design management for the environment of a welfare policy for the aged.