• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4C
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• pp.318-323
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• 2006

In this paper we propose three methods to generate short hopping sequences for the frequency hopping system. First, we explain the one coincidence set of sequences and the polyphase power residue seqences which have been known previously, and we suggest a method by modifying the one coincidence sequence and two methods by using the power residue sequences. We verify that the optimal position deleted-power residue sequences have the best Hamming autocorrelation property and the first position deleted-power residue sequences and the modified one coincidence sequences follows with respect to Hamming autocorrelation. We also explain that these sequences have the good balance property and can be implemented with low complexity.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.299.2-299
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• 2001

• Journal of the Korean Society of Radiology
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• v.12 no.5
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• pp.557-563
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• 2018

Coincidence summing correction effects are known to be greater as the efficiency of the detector increases and as the distance between the source and the detector increases. A point source($^{60}Co$) was used to vary the distance in the direction of the detector's center axis and in the radial direction to obtain the P/T ratio for Coincidence summing correction calibration. In this study, values for coincidence summing corrected calibration of the values in the central and radial directions were applied to the mixed volume source(450 ml CRM source) to compare the overall peak efficiency change according to P/T with Geant4. In addition, the efficiency obtained from the mapping method is applied to the seaweed, a marine sample, and the compatibility of the P/T ratio with the detector and sample very dose together. The efficiency corrected to 1,836 keV was applied to the energy zone affected by the efficiency of 500 keV and the relative error of the measured and corrected values was well matcched by the 3.2 % peak efficiency correction. As with 450 mL CRM source, the larger the volume, the lower the P/T ratio was by ${\pm}5%$. This is due to the increased scattering of gamma-rays emitted as the source becomes farther away from the detector, and this change in P/T has been confirmed to affect the Coincidence summing corrected peak efficiency.

• 대한방사선방어학회:학술대회논문집
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• 2009.04a
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• pp.230-231
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• 2009

• Journal of the Korean Institute of Telematics and Electronics
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• v.4 no.2
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• pp.3-15
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• 1967

In the design of a portable Gamma-ray transistorized steel pipe thickness gauge, a pulse height discriminator and an anti-coincidence circuit could be eliminated by using a thin, less than 1/2inch, NaI(Tl) scintillation crystal in the detecting probe. This method could provide an economic design and fabrication of a gamma-ray back-scattering gauge allowing allmost the same accuracy and stability compared with the exsisting method. A gauge had been designed and fabricated with the above method and its accuracy was experimentall tested for the 200$^{\circ}C$ high temperature steel pipes. The result showed that the thermal drift was less than y percent which was acceptabel in the practical applications.

• Nuclear Engineering and Technology
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• v.19 no.2
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• pp.107-114
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• 1987

Using a solution of $^{137}$ Cs as a tracer, radioactivity of a $^{137}$ Cs solution is measured by coincidence and anticoincidence counting methods. Sample sources in this study are fabricated by mixing $^{137}$ Cs with tracer, and the mixing ratios are 1/3 and 1/5, respectively in coincidence and anticoincidence methods. Specific activities of a $^{137}$ Cs solution are calculated by means of f-channel low energy threshold level variation and efficiency extrapolation. The results obtained by coincidence and anticoincidence counting methods are 552.78 kBq/g and 554.32kBq/g, respectively on the reference date and the combined uncertainties are 1.60kBq/g and 1.51kBq/g for each method. These two results show a good agreement within the uncertainty range.

• Journal of applied mathematics & informatics
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• v.27 no.3_4
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• pp.639-651
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• 2009

In this paper, we study a discrete Leslie-Gower one-predator two-prey model. By using the method of coincidence degree and some techniques, we obtain the existence of at least one positive periodic solution of the system. By linalization of the model at positive periodic solution and construction of Lyapunov function, sufficient conditions are obtained to ensure the global stability of the positive periodic solution. Numerical simulations are carried out to explain the analytical findings.

• Journal of Environmental Science International
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• v.18 no.12
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• pp.1427-1436
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• 2009

The purpose of this study was to explain community structure for actual vegetation and their environment variables in Anmyeon Island. Samples were collected for 106 plots using ZM phytosociology method and coincidence method. Actual vegetation were classified into three vegetations types(forest vegetation type, maritime vegetation type, lake vegetation type) and eleven community units. Pourthiaea villosa community in forest vegetation type was divided into 5 groups such as Carpinus coreana group, Pinus rigida group, Chamaecyparis obtusa group, Castanea crenata group and Typical group. Maritime vegetation type was divided into 3 communities, such as Vitex rotundifolia community, Koelreuteria paniculata community and Suaeda japonica community. V. rotundifolia community was subdivided into 2 groups, Rosa rugosa group and Diodia teres group. K. paniculata community was subdivided into 2 groups, Grewia biloba var. parviflora group and Typical group. Lake vegetation type was divided into 1 community, Nelumbo nucifera community. And it was entirely classified into 11 community units.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.359-366
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• 2002

Direct Integration method(D.I) and Mode Superposition method(M.S) are used widely in dynamic analysis method for structure with isolation devices. D.I is used firstly because it is consider to nonlinearity of isolation device. M.S is applied in elastic region, but it is difficult to apply M.S because coincidence with othogonality condition in the case of adding the damping of isolation device. In this study, the method for calculation of damping ratio of isolated structure is proposed, and proposed method is verified with analysis for example structure.

• 전기의세계
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• v.19 no.6
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• pp.1-7
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• 1970

In this paper, to determine process dynamic characteristics, the correlation method for measuring the impulse response of process using a pseudo-random binary signal as the test signal instead of white noise was studied. The error caused by using the signal of Mesquence signal generator which was built up by the authors was analysed. Experments were performed on the 1st and 2nd order lag systems and the results were in good coincidence with theoretical values. It is expected that applying these results, it may be possible to develop a continuous measuring method adaptable to modern control systems.