• Communications of the Korean Mathematical Society
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• v.29 no.4
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• pp.555-568
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• 2014

A set with an operation defined on a family of subsets is studied. The operation is used to generalize the topological space itself. The operation defines the operation-open subsets in the set. Relations are studied among two types of the interiors and the closures of subsets. Some properties of maximal operation-open sets are obtained. Semi-open sets and pre-open sets are defined in the sets with operations and some relations among them are proved.

• Proceedings of the KSRS Conference
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• v.1
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• pp.208-211
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• 2006

The contents of RF test set which can be used for checking the function and performance of 13m antenna installed in KARI site are described in this paper. For the purpose of considering RF test set as the transceiver in COMS, it is designed to retransmit the LRIT and HRIT in L-Band after receiving them in S-Band from 13m antenna. Additionally, this set has a function to turnaround raging tone used for the measurement of distance between satellite and 13m antenna. The required all equipments of RF test set are summarized with configuration. Measurements of several equipments which have already been delivered are described in this paper. The assembled RF test set will be used for the verification of 13m antenna

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.5 s.335
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• pp.9-14
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• 2005

Simulation method for a pure radio-frequency (rf) mode of reflection-type and a pure rf mode of transmission-type radio-frequency single-electron transistor (RF-SET) operation is introduced. In this method, the solutions of differential equations based on Kirchhoff's law are obtained self-consistently at frequency-domain. Also, the steady-sate single-electron transistor (SET) current model and the time-dependent SET current model are used in this method. The reflected wave of a typical reflection-type RF-SET and the transmitted wave of a typical transmission-type RF-SET are calculated, and the accuracy of our developed method including the steady-state SET current model is verified with the method introduced by reference 2. At high frequency over GHz, results of our developed method including the time-dependent SET current model are considerably different from that including the steady-state SET current model. At high frequency over GHz, an exact time-dependent SET current model is needed to analyze RF-SET operation.

• Journal of the Korean Operations Research and Management Science Society
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• v.22 no.3
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• pp.99-111
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• 1997

We consider a production system with post-operation and early set-up. As soon as there are no more units(raw materials) to process and the machine becomes idle, it undergoes a post-operation. After the post operation, if the number of waiting units is greater than or equal to m, it begins a set-up. After the set-up, if the number of units is greater than or equal to N($\geq$m), it begins to process the units. We first analyze the system by employing the decomposition property of the vacation queue. We, then, propose an algorithm that finds the optimal threshold values ($m^*$, $N^*$). Finally we present some numerical examples and interprete the system behavior.

• The Korean Journal of Food And Nutrition
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• v.31 no.2
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• pp.272-277
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• 2018

This research was conducted to elucidate the optimum conditions for the antibacterial activity of konjak jelly using the evolutionary operation-factorial design technique. In the first set of experiments, concentration of a coagulation agent, soaking liquid, and temperature of water were set to 0.4%, $0.6{\times}10^{-2}N$, and $65^{\circ}C$ as a central point, respectively. The highest antibacterial activity was acquired at E21, in which the number of bacteria was 1.25 log cfu/g. Because the code of changes in the main effect was (-), it could be decided that the central point of the first set was not the optimum point. Although antibacterial activity in the second set was improved, the values of the main effect were higher than that of changes in the mean effect. The central point of third set was concentration of coagulation agent 0.8%, concentration of soaking liquid $1.0{\times}10^{-2}N$, and temperature of water $65^{\circ}C$. It was found that the antibacterial activity of central point in the third set was highest among all the tested set. Further, all the necessary conditions were appropriate to reach the optimum condition. The antibacterial activity of the central point in third set was more than 1,000 times higher than that of E11, in first set.

• Journal of Power Electronics
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• v.14 no.1
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• pp.22-29
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• 2014

Current sharing between modules in a converter parallel operation is very important for the reliability of the system. This paper proposes an improved droop method that can effectively improve current sharing accuracy. The proposed method adaptively adjusts the output voltage set-point of each module according to the current set-points. Unlike conventional droop control, modules share a signal line to communicate with each other. Nevertheless, since signals are simple and in digital form, the complexity of the circuitry is much less and noise immunity is much better than those of conventional methods utilizing communication. The operation principle and design procedure of the proposed method are described in detail. Results of the experiment on two boost converters operating in parallel under the specification of a TFT LCD TV panel power supply verify the validity of the proposed scheme.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1329-1330
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• 2007

Phase-change random access memory(PRAM) has many advantages compare with the existing memory. For example, fast programming speed, low programming voltage, high sensing margin, low power consume and long cyclability of read/write. Though it has many advantages, there are some points which must be improved. So, we invented and studied new constitution of $Ge_{1}Se_{1}Te_{2}$ chalcogenide material. Actually, the performance properties have been improved surprisingly. However, crystallization time was as long as ever for amorphization time. In this paper, we studied in order to make set operation time and reset operation voltage reduced. In the present work, by alloying Sb in $Ge_{1}Se_{1}Te_{2}$. we could confirm that improved its set operation time and reset operation voltage. As a result, the method of Sb-alloyed $Ge_{1}Se_{1}Te_{2}$ can be solution to decrease the set operation time and reset operation voltage.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.4
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• pp.662-674
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• 1997

In order to post process the vector-quantized images employing the theory of projections onto convex sets or the constrained minimization technique, the the projector onto QCS(quantization constraint set) as well as the filter that smoothes the lock boundaries should be investigated theoretically. The basic idea behind the projection onto QCS is to prevent the processed data from diverging from the original quantization region in order to reduce the blurring artifacts caused by a filtering operation. However, since the Voronoi regions in order to reduce the blurring artifacts caused by a filtering operation. However, since the Voronoi regions in the vector quantization are arbitrarilly shaped unless the vector quantization has a structural code book, the implementation of the projection onto QCS is very complicate. This paper mathematically analyzes the projection onto QCS from the viewpoit of minimizing the mean square error. Through the analysis, it has been revealed that the projection onto a subset of the QCS yields lower distortion than the projection onto QCS does. Searching for an optimal constraint set is not easy and the operation of the projector is complicate, since the shape of optimal constraint set is dependent on the statistical characteristics between the filtered and original images. Therefore, we proposed a hyper-cube as a constraint set that enables a simple projection. It sill be also shown that a proper filtering technique followed by the projection onto the hyper-cube can reduce the quantization distortion by theory and experiment.

• Korean Journal of Computational Design and Engineering
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• v.6 no.1
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• pp.24-30
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• 2001

An efficient and robust algorithm to compute the exact Voronoi diagram of a circle set is presented. The circles are located in a two dimensional Euclidean space, the radii of the circles are non-negative and not necessarily equal, and the circles are allowed to intersect each other. The idea of the algorithm is to use the topology of the point set Voronoi diagram as a seed so that the correct topology of the circle set Voronoi diagram can be obtained through a number of edge flipping operations. Then, the geometries of the Voronoi edges of the circle set Voronoi diagram are computed. In particular, this paper discusses the topological aspect of the algorithm, and the following paper discusses the geometrical aspect. The main advantages of the proposed algorithm are in its robustness, speed, and the simplicity in its concept as well as implementation. Since the algorithm is based on the result of the point set Voronoi diagram and the flipping operation is the only topological operation, the algorithm is always as stable as the Voronoi diagram construction algorithm of a point set.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1257-1265
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• 2004

In this paper, We describe a change set that is to manage historical information and to maintain ontologies during long term. We propose several storage policies of ontology using a change set. A change set includes a change operation set and temporal dimensions. A change operation set is composed with schema change operations and data change operations. We propose three storage policies that are storing all the change sets and storing the change sets and versions periodically, storing the change sets and the versions using sum of change operations. Also, we present the experimental results for evaluating the performance of different storage policies.