• Journal of applied mathematics & informatics
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• v.41 no.3
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• pp.511-524
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• 2023

An L(p₁, p₂, p₃, . . . , p_m)-labeling of a graph G is an assignment of non-negative integers, called as labels, to the vertices such that the vertices at distance i should have at least pi as their label difference. If p₁ = 4, p₂ = 3, p₃ = 2, p₄ = 1, then it is called a L(4, 3, 2, 1)-labeling which is widely studied in the literature. A L(4, 3, 2, 1)-path coloring of graphs, is a labeling g : V (G) → Z⁺ such that there exists at least one path P between every pair of vertices in which the labeling restricted to this path is a L(4, 3, 2, 1)-labeling. This concept was defined and results for some simple graphs were obtained by the same authors in an earlier article. In this article, we study the concept of L(4, 3, 2, 1)-path coloring for complete bipartite graphs, 2-edge connected split graph, Cartesian product and join of two graphs and prove an existence theorem for the same.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.235-240
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• 2002

This paper shows the desist concept of an ATS(Antenna Tracking Software) to control the movement of the MSC(Multi-Spectral Camera) antenna. The MSC has a two-axes directional X-band antenna for image transmission to KGS(KOMSAT2 Ground Station). The main objective of the ATS is to drive the APM(Antenna Pointing Mechanism) to the required elevation and the azimuth position according to an appropriate TPF(Tracking Parameter File). The ATS is implemented as one task of the SBC(Single Board Computer) software, which uses VxWorks as a real time OS. The ATS has several operational modes such as STANDBY mode, First EL mode, First AZ mode, Normal Operation mode, and so on. The ATS uses two PI controllers fur the velocity and the position loop respectively, to satisfy the requirements specification. In order to show the feasibility of the described design concept, the various simulations and the experiments are performed under specific test configuration.

• Journal of Science Education
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• v.36 no.1
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• pp.84-93
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• 2012

We have studied possibilities of Peer Instruction(PI) to train in-service science teachers in elementary and middle schools through both degree of conceptual changes and investigating responses to questionaries. 169 teachers were attended and the subject for training was about light propagation to teach scientific conception about a pin hole camera. 6 conceptests were developed. Degree of conceptual changes was analyzed from results obtained from 24 elementary and 32 middle school teachers among them. On the other hand, answers to questionaries were obtained from 135. Relatively high gain near to about 0.7 in conceptual changes was obtained even though their initial levels were quite low. Interesting point is that elementary teachers have higher initial level and larger gain than middle school teachers. Teachers have very much enjoyed and showed strong support to PI for helping conceptual change, and willing to use PI to their own class. Also they conceived dealing concept in teacher training is very important and evaluated PI very positively for teacher training.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.6
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• pp.828-833
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• 2009

WWW which is an applicable massive set of document on the Web is a thesaurus of various information for users. However, Search engines spend a lot of time to retrieve necessary information and to filter out unnecessary information for user. In this paper, we propose the EFAM(the Extended Fuzzy AHP Method) model to manage the Web resource efficiently, and to make a decision in the problem of specific domain definitely. The EFAM model is concerned with the emotion analysis based on the domain corpus information, and it composed with systematic common concept grids by the knowledge of multiple experts. Therefore, The proposed the EFAM model can extract the documents by considering on the emotion criteria in the semantic context that is extracted concept from the corpus of specific domain and confirms that our model provides more efficient decision-making through an experiment than the conventional methods such as AHP and Fuzzy AHP which describe as a hierarchical structure elements about decision-making based on the alternatives, evaluation criteria, subjective attribute weight and fuzzy relation between concept and object.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.3
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• pp.232-238
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• 2015

A sensorless control algorithm of brushless DC (BLDC) motors with a model current based on 120 degree conduction mode is proposed in this paper. The rotor speed and position can be estimated using the current model of BLDC motor, which is a modified version of the conventional current model of permanent magnet synchronous motor. The rotor speed and position can be obtained using the difference of the actual current and the model current. The position error caused by the parameter errors of the model current is compensated using a PI controller and the feedback loop of the real current. The validity of the proposed sensorless control algorithm is verified through simulation.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1225-1230
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• 2012

A new unsymmetrical zinc phthalocyanine has been designed and synthesized based on the 'push-pull' and extended ${\pi}$-conjugation concept for the dye-sensitized solar cells. Three tert-butoxy groups, which act as electron releasing ('push'), enhance the solubility of phthalocyanine in common organic solvents and reduce the aggregation. Hydroxy substituted 9,10-anthraquinones act as electron acceptors ('pull') for the study of photoinduced electron transfer processes as well as grafting onto nanocrystalline $TiO_2$. The new unsymmetrical zinc phthalocyanine was fully characterized by FTIR, UV-vis, $^1H$ NMR, cyclic voltammetry and differential pulse voltammetry. The new sensitizer was tested in dye-sensitized solar cells, and gave a better performance.

• Bulletin of the Korean Mathematical Society
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• v.48 no.6
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• pp.1207-1218
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• 2011

Let * be a star-operation on an integral domain R, and let $\mathfrak{I}_*^+(R)$ be the semigroup of *-invertible integral *-ideals of R. In this article, we introduce the concept of a *-coatom, and we then characterize when $\mathfrak{I}_*^+(R)$ is a free semigroup with a set of free generators consisting of *-coatoms. In particular, we show that $\mathfrak{I}_*^+(R)$ is a free semigroup if and only if R is a Krull domain and each ${\upsilon}$-invertible ${\upsilon}$-ideal is *-invertible. As a corollary, we obtain some characterizations of *-Dedekind domains.

• Structural Engineering and Mechanics
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• v.10 no.1
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• pp.27-36
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• 2000

The Oktalok nodal connection system is an aesthetic and efficient system. It has been widely used throughout Australia. The paper will briefly introduce the concept and application of the Oktalok nodal system. The existing design method is based on the assumption that the joints are pin-ended, i.e., the rotational stiffness of the joints is zero. However the ultimate capacity of the frame may increase significantly depending on the rotational stiffness of the joints. Stiffness tests and finite element simulations were carried out to determine the rotational stiffness of the Oktalok joints. Column buckling tests and non-linear finite element analyses were performed to determine the member capacity of columns with semi-rigid end conditions. A simple formulae for the effective length factor of column buckling is derived based on the above experimental and theoretical investigations.

• Communications of the Korean Mathematical Society
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• v.28 no.4
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• pp.819-825
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• 2013

Similarly to Tychonoff product, we introduce the concept of generalized product topology which is different from the notion of product of generalized topologies in [$\acute{A}$. $Cs\acute{a}sz\acute{a}r$, Acta Math. Hungar. 123 (2009), 127-132] for generalized topology and obtain some properties about it. Besides, we prove that connectedness, ${\sigma}$-connectedness and ${\alpha}$-connectedness are all preserved under this product.

• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.165-168
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• 2005

We overview the GRAPE (GRAvity piPE) project. The goal of the GRAPE project is to accelerate the astrophysical N-body simulations. Since almost all computing time is spent for the evaluation of the gravitational force between particles, we can greatly accelerate many N-body simulations by developing a specialized hardware for the force calculation. In 1989, the first such hardware, GRAPE-1, was completed, with the peak speed of 120 Mflops. In 2003, GRAPE-6 was completed, with the peak speed of 64 Tflops, which is nearly 106 times faster than GRAPE-l and was the fastest computer at that time. In this paper, we review the basic concept of the GRAPE hardwares, the history of the GRAPE project, and two ongoing projects, GRAPE-DR and Project Milkyway.