• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.1
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• pp.17-23
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• 2020

Upper stage of launch vehicle mainly injects a lunar explorer from low earth orbit to the moon at a distance of 380,000 km. In foreign lunar explorer, the upper stage is separated from the explorer after the explorer is injected into the earth-moon transfer trajectory, and the lunar explorer then uses on-board propellant to carry out mid-course correction maneuvers and lunar orbit insertion maneuvers. This study describes a newly presented small liquid upper stage. Using a small liquid upper stage with a wet mass of 2.9 tonnes, the lunar explorer not only can be injected earth-moon transfer trajectory but also can be performed lunar orbit insertion. This study provides acceptable mass range of the lunar explorer and the scope of acceptable mission range also describes based on the launch from Naro Space Center.

• Journal of the Korea Convergence Society
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• v.8 no.5
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• pp.145-153
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• 2017

As success stories of using virtual reality (VR) have become more prevalent, interest in performance-related technology has rapidly increased around the world. Performances such as, Cirque du Soleil had much success in using video technology, these VR applications have enabled experiences using digital image technology. However, critics have claimed that the completeness and diversity of visual content is reduced, due to insufficient storylines, spatial composition, and partial use of the entire visual field. Therefore, the design of a performance using digital image technology should consider the characteristics of the production stage to be different from real world performances. In this study, the visual space of the stage, the method of creating space for the stage, and the movement of the performer and utilization of the performance was analyzed. Through this, It transferred the limitation of the traditional stage into the space and time of the image and opened the possibilities of the tran­-media.

• Korean Institute of Interior Design Journal
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• v.25 no.6
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• pp.79-88
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• 2016

The purpose of this study was to suggest ways to vitalize residential container architecture by identifying the building process of domestic residential container architecture and analyzing various problems appeared in the process and status of construction related to planning, design, and construction. Conclusion and suggestions of this study are as follows.; firstly, according to the current situation of domestic residential container architecture, the usage was planned mainly for accommodation. Secondly, For planning background of planning preparation stage, economic benefit for long-term residence individuality and diversity for long short term complex residence were the primary planning backgrounds. Thirdly, for floor planning of planning design stage, space planning for various purposes is necessary as creating inter-space, wide LDK space, and loft by using narrow and long container for the long-term residence. Lastly, For construction stage, ways to reduce personnel expenses are being required by reducing the term of works and simplifying the processing stage by running factory production and field construction in parallel. If reduction method of construction cost through energy saving and mass production system is considered in the future, it would be possible to expand the development to dormitory and community housing for university students who are pressured by housing cost.

• Journal of the Korean Institute of Rural Architecture
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• v.13 no.4
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• pp.115-124
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• 2011

This study examines the process of urban formation in the city of Yanji. The analysis is done by the change of street pattern and major facility location in a timely manner by appling space syntax method. This research categorizes the pattern of the urban growth focused on two urban forms, street and major buildings, in the city and is offered of the meaning of the first value on interpretation of the urban growth in the city of Yanji. The result of the research are as follows. First, the period of the city transformation is divided into four stage; intuitive period, grid-iron formative period, consolidation period, and urban expansion period. Second, characteristics of each stage have been analyzed. At the first stage, the city started to frame along both buildings and streets which were placed without a plan. At the second stage, the city was planned and constructed into new grid-iron pattern ignoring existing context by Jananese colony. At the consolidation period, the road system expands from the city center toward suburban. At the last expansion period, the shape of the city has complicated its shape with complex road system. This study contributes to provide a basic analysis and data to investigate how the Yanji city has evolved over period of time. But further continuous research should be done for future urban development of the Yanji city.

• International Journal of Aeronautical and Space Sciences
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• v.4 no.2
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• pp.17-25
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• 2003

Simple methods are developed to predict temperatures of a satellite box during launch stage. The box is mounted on outer surface of satellite and directly exposed to space thermal environment for the time period from fairing jettison to separation. These simple methods are to solve a 1st order ordinary differential equation (ODE) which is simplified from the governing equation after applying several assumptions. The existence of analytical solution for the 1st order ODE is determined depending on treatment of time-dependent molecular heating term. Even for the case that the analytical solution is not available due to the time dependent term, the 1st order ODE can be solved by relatively simple numerical techniques. The temperature difference between two different approaches (analytical and numerical solutions) is relatively small (Jess than $1^{\circ}C$ along the time line) when they are applied to STSAT-I launch scenario. The present methods can be generally used as tools to quickly check whether a satellite box is safe against space environment during the launch stage for the case that the detailed thermal analysis is not available.

• Journal of Astronomy and Space Sciences
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• v.3 no.1
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• pp.41-51
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• 1986

Two-photometric light curves(Oh and Chen 1984) of the eclipsing binary TX UMa have been analyzed by the method of differential corrections of the model of Wilson and Devinney (1971). The system found to be simi-detached with the cooler and less massive component filling its Roche lobe. The absolute dimensions have been derived from the results of the photometric solutions with the spectroscopic elements of Hiltner(1945). It is assumed that the B8V primary component is on the zero main sequence stage of the core hydrogen burning and the secondary is at the core contraction stage after the shell hydrogen burning stage according to the Iben's (1967) evolutional tracks for $3.0m_\odot$ and $1.0m_\odot$ .

• Smart Structures and Systems
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• v.25 no.3
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• pp.345-368
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• 2020

The present work proposes a self-controlled multi-stage optimization method for damage identification of structures utilizing standard particle swarm optimization (PSO) algorithm. Damage identification problem is formulated as an inverse optimization problem where damage severity in each element of the structure is considered as optimization variables. An efficient objective function is formed using the first few frequencies and mode shapes of the structure. This objective function is minimized by a self-controlled multi-stage strategy to identify and quantify the damage extent of the structural members. In the first stage, standard PSO is utilized to get an initial solution to the problem. Subsequently, the algorithm identifies the most damage-prone elements of the structure using an adaptable threshold value of damage severity. These identified elements are included in the search space of the standard PSO at the next stage. Thus, the algorithm reduces the dimension of the search space and subsequently increases the accuracy of damage prediction with a considerable reduction in computational cost. The efficiency of the proposed method is investigated and compared with available results through three numerical examples considering both with and without noise. The obtained results demonstrate the accuracy of the present method can accurately estimate the location and severity of multi-damage cases in the structural systems with less computational cost.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.37-42
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• 2004

The primary objective of this paper is to trace the post-buckling behavior of space trusses in the inelastic range. Modeled member material behavior characteristics of struts in the post-critical elasto-plastic stage are determined and three types of idealized hardening rules are described. To perform this analysis, the present work is used the current stiffness parameter method combined with the cylinderical arc-length method. Numerical examples are presented to illustrate the accuracy and the application of the numerical solutions introduced above.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.34
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• pp.107-114
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• 1995

The objective of this study is to design a one-stage dynamic prediction model with Kalman state space model. For a model verification, it is compared with EWMA(Exponentially Weighed Moving Average) model. The model designed in this research can be extended to process prevention control and quality monitoring.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.8
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• pp.509-513
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• 2000

This paper deals with the parallel operation of space vector PWM for large capacity inverter system. To enlarge the capacity of inverter system and to reduce the current ripples on inverter output side, two or more inverters are operated in parallel. In this paper, a new parallel operation strategy which minimizes the harmonic distortion of the output stage is described. The proposed method is developed on the basis of the space-vector PWM in order to increase the linearly controllable voltage range. With the help of the proposed voltage synthesis method, the total harmonic distortion of the output stage can be greatly reduced in compared with that of conventional method with sinusoidal PWM or that of the single inverter operation case. The experimental results with reduced scale test show the feasibility of the proposed voltage synthesis method.