• International Journal of Aeronautical and Space Sciences
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• v.18 no.1
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• pp.99-107
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• 2017

In this work, the nutation control of rigid spacecraft with only two momentum wheels is addressed by applying the feedback linearization technique. In this strategy, the primary performance index is to regulate the nutational angle by the momentum control of wheels. The spacecraft attitude equations of motion are transformed to a general linearized form by feedback linearization technique, including a guaranteed control law promising the internal dynamics stability to accomplish the nutation angle small. It is proven that the configuration of inertia properties plays a key role in analyzing spacecraft energy level. The behavior of the momentum wheels is also studied analytically and numerically. Finally, the effectiveness of the proposed nonlinear control law for the momentum transfer is verified by conducting numerical simulations.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.38.2-38.2
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• 2008

In Korean historical documents, there are a great number of the records for various astronomical events. In particular, historical documents of the Joseon dynasty also have the records containing observational data by an astronomical instrument. However, a quantitative analysis for the accuracy of observational values have never been studied, although there are some studies on the truth of the records themselves. Hence, we investigated observation errors during the period of the Joseon dynasty from the records of Joseon-Wang-Jo-Sil-Lok (the Annals of the Joseon Dynasty) and Seung-Jeong-Won-Il-Gi (Daily Records of the Royal Secretariat). We used the records of the Mars, supernova 1604, and Halley's Comet, and found that observational values before the Hideyoshi invasions in 1592 are relatively more accurate than those after then. However, because the number of cases used in this study is small, we think that more studies are needed to confirm our results. Nonetheless, we reckon our work will be of service to understand astronomical records of the Joseon dynasty.

• Journal of the Korean Mathematical Society
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• v.48 no.1
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• pp.159-167
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• 2011

We consider a curve $\alpha$= $\alpha$(s) in Minkowski 3-space $E_1^3$ and denote by {T, N, B} the Frenet frame of $\alpha$. We say that $\alpha$ is a slant helix if there exists a fixed direction U of $E_1^3$ such that the function is constant. In this work we give characterizations of slant helices in terms of the curvature and torsion of $\alpha$. Finally, we discuss the tangent and binormal indicatrices of slant curves, proving that they are helices in $E_1^3$.

• Journal of information and communication convergence engineering
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• v.6 no.3
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• pp.261-265
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• 2008

This work presents a simplified efficient blind detection algorithm for orthogonal space-time codes(OSTBC). First, the proposed decoder exploits a proper decomposition approach of the upper triangular matrix R, which resulted from Cholesky-factorization of the composition channel matrix, to form an easy-to-solve blind detection equation. Secondly, in order to avoid suffering from the high computational load, the proposed decoder applies a sub-optimal QR-based decoder. Computer simulation results verify that the proposed decoder allows to significantly reduce computational complexity while still satisfying the bit-error-rate(BER) performance.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.104.2-104.2
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• 2014

The RGB Bayer filter system consists of mosaic R, G, and B filters on the grid of photo sensors with which typical commercial DSLR (Digital Single Lens Reflex) cameras and CCD/CMOS cameras are taken. Many unique astronomical data taken with RGB Bayer filter systems are available, including transient objects, e.g., supernovae, variable stars, and solar system bodies. The utilization of such data in scientific research strongly requires reliable photometry transformation methods. In this work, we develop a series of formulae to derive magnitudes in the Johnson-Cousins BVR filter system from those in the RGB Bayer filter system.

• Journal of the Chungcheong Mathematical Society
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• v.29 no.2
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• pp.287-328
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• 2016

In the current work, we define and find the general solution of the decic functional equation g(x + 5y) - 10g(x + 4y) + 45g(x + 3y) - 120g(x + 2y) + 210g(x + y) - 252g(x) + 210g(x - y) - 120g(x - 2y) + 45g(x - 3y) - 10g(x - 4y) + g(x - 5y) = 10!g(y) where 10! = 3628800. We also investigate and establish the generalized Ulam-Hyers stability of this functional equation in Banach spaces, generalized 2-normed spaces and random normed spaces by using direct and fixed point methods.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.1
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• pp.183-190
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• 2012

Mobile web applications are different from desktop web applications because of their small screen size and small user input devices. Therefore user interface designers have spent their effort and time to re-design the user interface of mobile web applications to meet these differences. In this paper, we introduce five user interface patterns for mobile web applications to reduce their effort and time. Two of them are for utilizing small screen size efficiently, and they are space overloading pattern and data filtering pattern. These patterns enable designers to reduce screen usage. The other three patterns - data suggestion pattern, input reuse pattern, and incremental data input pattern - are for helping users' data input on mobile devices. These three patterns enable users to reduce direct data input. Our work will help user interface designers develop mobile web interface to utilize screen space efficiently and get data with less errors and less efforts from users.

• Transactions on Electrical and Electronic Materials
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• v.15 no.3
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• pp.125-129
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• 2014

A dataset can be clustered by merging the bucket indices that come from the random projection of locality sensitive hashing functions. It should be noted that for this to work the merging interval must be calculated first. To improve the feasibility of large scale data clustering in high dimensional space we propose an enhanced Locality Sensitive Hashing Clustering Method. Firstly, multiple hashing functions are generated. Secondly, data points are projected to bucket indices. Thirdly, bucket indices are clustered to get class labels. Experimental results showed that on synthetic datasets this method achieves high accuracy at much improved cluster speeds. These attributes make it well suited to clustering data in high dimensional space.

• Proceedings of the Korean Institute of Interior Design Conference
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• 1999.04a
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• pp.27-30
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• 1999

Telecommuting becomes a new form of work according to the development of computer and telecommunication technology. Therefore, the purpose of this study is to provide basic data for the interior space planning of telecommuting centers by means of surveying office workers' opinions. The major findings of this research are as follows. The opinion about whether to use telecommuting center if provided is showed highly positively. In the matter of space type of telecommuting center, 'mixing type I (open plan office but division with high partition)' is the most preferred, the next is 'closed type'. The most preferred type of workstation is 'individual space type ', the next if 'X type' and the third is 'link type'. referred partition height is '1m300-1,500mm'.

• Journal of the Korean Institute of Rural Architecture
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• v.5 no.3
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• pp.8-21
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• 2003

The purpose of this study was to work out the strategies for developing the east coastal community-base resort activating the community economy. The results of this study were as follows; presented village unit resort development that secure unique community activity to seashore village inhabitants and offer natural rest space and recreation space to user for the idealest development direction. And presented space composition direction so that can develop nature rest ball such as nature walk road that introduce concept of "The street" in this resort development. Also, through belt style development, proposed resources between the seashore village that must share reciprocity.