• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.6
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• pp.67-74
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• 2006

In this paper, a tiled display system is developed to get a high-resolution image in visualization of large-scale structural analysis data with low-resolution display devices and low-cost cluster computer system. Concerning the hardware system, some of the crucial points are investigated, and a new beam-projector positioner is designed and manufactured to resolve the keystone phenomena which result in distorted image. In the development of tiled display software, Qt and OpenGL are utilized for GUI and rendering, respectively. To obtain the entire tiled image, LAM-MPI is utilized to synchronize the several sub-images produced from each cluster computer node.

• International Journal of Aeronautical and Space Sciences
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• v.11 no.4
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• pp.326-337
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• 2010

This work addresses problems regarding trajectory planning for unmanned aerial vehicle sensors. Such sensors are used for taking measurements of large nonlinear systems. The sensor investigations presented here entails methods for improving estimations and predictions of large nonlinear systems. Thoroughly understanding the global system state typically requires probabilistic state estimation. Thus, in order to meet this requirement, the goal is to find trajectories such that the measurements along each trajectory minimize the expected error of the predicted state of the system. The considerable nonlinearity of the dynamics governing these systems necessitates the use of computationally costly Monte-Carlo estimation techniques, which are needed to update the state distribution over time. This computational burden renders planning to be infeasible since the search process must calculate the covariance of the posterior state estimate for each candidate path. To resolve this challenge, this work proposes to replace the computationally intensive numerical prediction process with an approximate covariance dynamics model learned using a nonlinear time-series regression. The use of autoregressive time-series featuring a regularized least squares algorithm facilitates the learning of accurate and efficient parametric models. The learned covariance dynamics are demonstrated to outperform other approximation strategies, such as linearization and partial ensemble propagation, when used for trajectory optimization, in terms of accuracy and speed, with examples of simplified weather forecasting.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.8
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• pp.33-40
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• 2006

A parallel computing strategy for finite element(FE) processing is described and implemented in nonlinear explicit FE code and its parallel performances are evaluated. A self-made linux-cluster supercomputer with 520 CPUs is used as a bench mark test bed. It is observed that speed-up is increased almost idealy even up to 256 CPUs for a large scale model. A communication over head and its effect on the parallel performance is also examined. Parallel performance is compare with the commercial code and developed code shows superior performance as the number of CPUs used are increased.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.3
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• pp.31-36
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• 2006

In this study, nonlinear static aeroelastic analysis system for a high-aspect-ratio wing are developed using the transonic small disturbance (TSD) and large deflection beam theory and validated. For the coupling between fluid and structure, the transformation of displacement from the structural mesh to aerodynamic one is performed by the shape function of the beam finite element and the inverse transformation of force by work equivalent load concept. Also, for the static aeroelastic analysis of the wing the use of TSD aerodynamics are justified. The validation of the system includes one of the efficient transformation methods of force and displacement.

• Bulletin of the Korean Space Science Society
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• 1993.10a
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• pp.21-21
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• 1993

The imaging areas of currently available optical detectors are relatively small to cope with large image areas such as telescope focal Planes. One Possibility to obtain large detection areas is to assemble mosaics of Charge Coupled Devices(CCDs) and drive them simultaneously. Parallel driving of many CCDs together rules out the possibility of individual tuning; however such optimisation is very important when the ultimate low light level performance is required particularly for new devices. In this work, a new concept has been developed for an entirely novel approach where the drive waveforms are multiplexed and interleaved. This simultaneously reduces the number of leadout connections and permits individual optimisation efficiently. The controller has been designed to include one electronic of component produced by CAD software where most of the digital circuits are integrated to minimise the component count and improve the efficiency of the system greatly. The software has an open architecture to permit convenient modificationl by the user to fit their specific purposes. The desire of controller allows great flexibility of system parameters by the softwa re, specifically for the compatibility to deal with any number of mixed CCDs and in any format within the practical limit. The system has been integrated to test the performance and the result is discussed for readout noise, system linearity and cross-talk between the CCDs. The system developed in this work can be applicable not only for astro nomical observation with a telescope but also in other related fields for low light level detection systems such as spectroscopic application, remote sensing and X-ray detecti13n systems with large sensing areas and high resolution.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.39.4-40
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• 2017

According to the Korean government's Long-term Space Development Plan 2040, "Creative space science research" is included in a statement to investigate the origin and evolution of the universe by conducting a series of Korean space telescope missions: launch of space telescopes on a small satellite and an international collaboration explorer by 2020, a mid-size domestic space telescope by 2030, and a large size Korea leading international space telescope by 2040. We studied the feasibility of the future Korean Space Telescope (KST) for a mid-size domestic satellite platform. In order to pursue the uniqueness of the science program, we consider a wide range of observing wavelength (0.2um ~ 2.0um) with a spectral resolution of R~6 in the NUV and optical bands, and R~30 for NIR, utilizing an off-axis TMS(Three Mirror System) optics with a wide field of view ($2{\times}4$ degrees) which is optimized for ultra-low surface brightness sources. The main science goals of the mission include investigations of the galaxy formation, cosmic web, and the cosmic background radiation in the NUV-NIR regions. In this paper, we present the science cases and several technical challenges to be resolved along with the future milestones for the success of the KST mission.

• Journal of the Korean housing association
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• v.22 no.1
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• pp.65-73
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• 2011

The purpose of this study is to find out the characteristics of area and spatial elements according to the building size and provide the guidelines for space planning of the child care center. This study used the content analysis method and analysis was made on the floor plans for 51 cases and the floor plans were converted to Autocad drawings to analyze the area. The results of this study were as follows; 1) Child care centers over 70% were single-attached building types which made it possible for creating outdoor environments for children. However, most small-size centers which had under 50 children did not have the facilities for outdoor activities. 2) In terms of spatial elements, the basic spaces of the small-size center were the classroom, bathroom, kitchen, office and reference room. The medium or large size centers had extra rooms for special activities and service spaces in addition to the basic spaces. 3) Classroom area per child was 2.65 m2 on average. Space composition ratio on average for care, staff, and service was programmed by 57%, 9%, 34% respectively. Small-size center had relatively more care space when compared to the others. In the case of large-size centers, there was a tendency that service space was increased, but care space was decreased.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.4
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• pp.307-314
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• 2009

The present paper briefly describes the space frame element and the fundamental strategies in computational elastic bifurcation theory of geometrically nonlinear, single load parameter conservative elastic spatial structures. A method for large deformation(rotation) analysis of space frame is based on an eulerian formulation, which takes into consideration the effects of large joint translations and rotations with finite deformation(rotation). The local member force-deformation relationships are based on the beam-column approach, and the change in member chord lengths caused by axial strain and flexural bowing are taken into account. and the derived geometric stiffness matrix is unsymmetric because of the fact that finite rotations are not commutative under addition. To detect the singular point such as bifurcation point, an iterative pin-pointing algorithm is proposed. And the path switching mode for bifurcation path is based on the non-negative eigen-value and it's corresponding eigen-vector. Some numerical examples for bifurcation analysis are carried out for a plane frame, plane circular arch and space dome structures are described.

• Journal of KIISE:Databases
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• v.32 no.1
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• pp.1-11
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• 2005

An aggregation query computes aggregate information over a data cube in the query range specified by a user Existing methods based on the prefix-sum approach use an additional cube called the prefix-sum cube(PC), to store the cumulative sums of data, causing a high space overhead. This space overhead not only leads to extra costs for storage devices, but also causes additional propagations of updates and longer access time on physical devices. In this paper, we propose a new prefix-sum cube called 'SPEC' which drastically reduces the space of the PC in a large data warehouse. The SPEC decreases the update propagation caused by the dependency between values in cells of the PC. We develop an effective algorithm which finds dense sub-cubes from a large data cube. We perform an extensive experiment with respect to various dimensions of the data cube and query sizes, and examine the effectiveness and performance ot our proposed method. Experimental results show that the SPEC significantly reduces the space of the PC while maintaining a reasonable query performance.

• Journal of Korean Society of Rural Planning
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• v.22 no.2
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• pp.67-75
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• 2016

This Research was carried out to investigate landscape characteristics of the traditional Chinese village through the landscape analysis. The Purpose of this study was to offer suggestions for improving Korea's traditional village scenery. This research was conducted by analysis about an important component of the landscape in Ping-shan traditional village. It was studied natural landscape, life landscapes, agricultural production landscapes and symbols landscape. This study was carried out through literature research, field research and interviews. The results of Chinese traditional village's landscape characteristic was First, Ping-shan traditional village was located on the basis of Feng-Shui settings. Second, Ping-shan traditional village was clan-based. Third, It is composed of a large green space on the outskirts of the village. Fourth, Ping-shan traditional village was a typical channel village. Fifth, Ping-shan traditional village was a living landscape with various features. sixth, Ping-shan traditional village was a lot of space to agricultural production, most of the arable land surround village. Suggestions for improving Korea's traditional village scenery are as follows ; First, proposes actively re-design on the base of defense fengshi landscape interpreted as a modern sense. Seconds, when large-scale farmland project is established in Korea, you can expect to gain knowledge from traditional Chinese village spacing. Thirds, It seems to require a study of the public space for festival. in the case of china, ancestral shrine space is center and space for festival. Fourth, It was important to seek knowledge about protection for frequent in flood plains in Korea's traditional village. Ping-shan traditional village was well-known for housing with contact water, connected channels and beautiful defense pond. Fifth, for improving Korea's traditional village scenery, we need to make various focus landscape features. Most of the visitors to Ping-shan traditional village was interested in the big and small beautiful landscapes and shelters.