• Journal of the Korean Society for Precision Engineering
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• v.11 no.6
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• pp.98-108
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• 1994

An assessment of a mathematical method of synthesing tire tread pitch noise spectra is studied. The method is based on the summation of phasors and the calculated spectra are conveniently generated as computer printout in the form of bar graph. The technique, its usefulness, its limitations and the implications of using such a model are discussed. This paper presents a basic study on optimum pitch arrangement for prediction and control of tire tread pitch noise in constraint condition relatied with tire properties, thus enabling optimum tread pitch arrangements to be determined at the design stage, by application of old tire tread pitch simulation.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.4
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• pp.1-8
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• 2007

Spray characteristics of a unlike triplet injector were investigated experimentally. Spray images and SMD of droplet were measured to evaluate the spray characteristics injected by liquid/gas combinations. G-L-G(Gas-Liquid-Gas), L-G-L(Liquid-Gas-Liquid) type of injector were used by changing the gas and liquid feed lines. The SMD graph shows that the droplet sizes decrease in the out of radial direction at a fixed gas Reynolds number. The SMD value of decreasing tendency shows that the more ethyl alcohol ratio increase, the more SMD value decrease.

• Journal of the Optical Society of Korea
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• v.15 no.3
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• pp.244-251
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• 2011

We propose a new 2-step phase-shifting digital holographic optical encryption technique and analyze tolerance error for this cipher system. 2-step phase-shifting digital holograms are acquired by moving the PZT mirror with phase step of 0 or ${\pi}$/2 in the reference beam path of the Mach-Zehnder type interferometer. Digital hologram with the encrypted information is Fourier transform hologram and is recorded on CCD camera with 256 gray-level quantized intensities. The decryption performance of binary bit data and image data is analyzed by considering error factors. One of the most important errors is quantization error in detecting the digital hologram intensity on CCD. The more the number of quantization error pixels and the variation of gray-level increase, the more the number of error bits increases for decryption. Computer experiments show the results to be carried out encryption and decryption with the proposed method and the graph to analyze the tolerance of the quantization error in the system.

• Journal of the Korea Society of Computer and Information
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• v.21 no.10
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• pp.1-10
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• 2016

In this paper, we propose an approach to generate machine readable context annotations for SPARQL Results. According to W3C Recommendations, the retrieved data from RDF or OWL data sources are represented in tabular form, in which each cell's data is described by only type and value. The simple query result form is generally useful, but it is not sufficient to explain the semantics of the data in query results. To explain the meaning of the data, appropriate annotations must be added to the query results. In this paper, we generate the annotations from the basic graph patterns in user's queries. We could also manipulate the original queries to complete the annotations. The generated annotations are represented using the RDFa syntax in our study. The RDFa expressions in HTML are machine-understandable. We believe that our work will improve the trustworthiness of query results and contribute to distribute the data to meet the vision of the Semantic Web.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.6
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• pp.981-986
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• 2011

In this paper, the module for measuring SpO2 and PPG(Photo Plethysmo Graphy) signal of human body and the module for wireless communication of these bio-signals to PC were developed. The program was developed to display transmitted SpO2 and PPG signal by various type data and graph without information loss during a emergency transfer. This system can be utilized as appropriate for remote medical care and a new market is expected, to be created according to revision of medical law.

• Honam Mathematical Journal
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• v.30 no.4
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• pp.589-602
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• 2008

As a survey-type article, the paper reviews various digital topological utilities from digital covering theory. Digital covering theory has strongly contributed to the calculation of the digital k-fundamental group of both a digital space(a set with k-adjacency or digital k-graph) and a digital product. Furthermore, it has been used in classifying digital spaces, establishing almost Van Kampen theory which is the digital version of van Kampen theorem in algebrate topology, developing the generalized universal covering property, and so forth. Finally, we remark on the digital k-surface structure of a Cartesian product of two simple closed $k_i$-curves in ${\mathbf{Z}}^n$, $i{\in}{1,2}$.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.433-435
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• 2007

Geographic wireless sensor networks use position information for Greedy routing. Greedy routing works well in dense network where as in sparse network it may fail and require the use of recovery algorithms. Recovery algorithms help the packet to get out of the communication void. However, these algorithms are generally costlier for resource constrained position based wireless sensor type networks. In the present work, we propose a Void Avoidance Algorithm (VAA); a novel idea based on virtual distance upgrading that allows wireless sensor nodes to remove all stuck nodes by transforming the routing graph and forward packet using greedy routing only without recovery algorithm. In VAA, the stuck node upgrades distance unless it finds next hop node which is closer to the destination than itself. VAA guarantees the packet delivery if there is a topologically valid path exists. NS-2 is used to evaluate the performance and correctness of VAA and compared the performance with GPSR. Simulation results show that our proposed algorithm achieves higher delivery ratio, lower energy consumption and efficient path.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.3
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• pp.210-216
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• 1984

An investigation of the effects of the size of mixing region determined by changing the position of fuel injection has been carried out. Measurements were made: the distribution of temperature and concentration profiles of the stable gas species, nitrogen oxide and total hydrocarbon in the flames. The results of this investigation show that variations of the size of mixing region produce major changes to the three type flow fields which significantly influence pollutant (NO, CO and THC) formation and energy release.

• The Journal of the Korea Contents Association
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• v.6 no.2
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• pp.93-98
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• 2006

The paper describes a method o( user feedback in order to enhance the retrieval system effectiveness. The existing fuzzification function adapting fuzzy technique has difficulty that 4 type graph is made each time user select components. In this paper, to overcome this weak point of feedback, we proposed the interaction function using gaussian function that gives different learning rate according to choice of components with same function. We suggest the most efficient dynamic interaction function based on comparison of retrieval performance according to parameter of function. And then, we will construct the efficient retrieval system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.576-579
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• 2002

This paper presents the jacobian analysis of new type Casing Oscillator using the inverse kinematics, and to search for it's singularities through the jacobian analysis. All parallel manipulator have some singularities in workspace or it's outside workspace. Singularities were cleared by many other study of parallel manipulator f3r that reason recent publication of device control. In this paper defined that singularities of new file of Casing Oscillator and, to show it's graph. Finally this paper will be used for a practical example for construction spot, aviation simulator, vehicles simulator, military equipment etc.