• Journal of Korea Water Resources Association
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• v.43 no.10
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• pp.843-850
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• 2010

By employing multi-directional random waves, a parameter controlling the force acting on a long caisson breakwater is investigated in detail. Both JONSWAP (Joint North Sea Wave Project) and asymmetric directional spectra are adopted for frequency and directional spectra. It is found that the parameter decreases as the length of caisson and the angle of main direction of incident waves increase. Furthermore, the parameter is much similar to that of regular waves as the maximum spreading parameter $s_{max}$ increases. The parameter, however, decreases as asymmetry parameter ${\mu}$ increases when the main direction of incident waves is oblique to the breakwater.

• Journal of IKEEE
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• v.8 no.1 s.14
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• pp.145-151
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• 2004

For wide-band spread spectrum communication systems such as IMT-2000, a digital matched filter is a key device for rapid spreading code synchronization. Although a digital matched filter can be implemented easily, large power consumption at the higher chip rate and large summation delay of longer chip length are the bottleneck of practical use. In this paper, we propose a optimized partial correlation digital matched filter structure which can be constructed of the so-called generalized hierarchical Golay sequence. a partial correlation structure can reduce the number of correlators, but enlarge the size of flip-flops. In this paper, The proposed approach focuses on efficient circuit size, power dissipation, maintaining the operating throughput. A proposed digital matched filter reduce the size of flip-flops by rounding method. and it reduces about 45 percentages of power dissipation and chip area as compared with digital matched filter which is not rounded. rounding. The proposed architecture was verified by using Xilinx FPGA.

• Geophysics and Geophysical Exploration
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• v.10 no.1
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• pp.69-76
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• 2007

High-frequency electromagnetic (EM) wave propagation associated with borehole ground-penetrating radar (GPR) is a complicated phenomenon. To improve the understanding of the governing physical processes, we employ a finite-difference time-domain solution of Maxwell's equations in cylindrical coordinates. This approach allows us to model the full EM wavefield associated with crosshole GPR surveys. Furthermore, the use of cylindrical coordinates is computationally efficient, correctly emulates the three-dimensional geometrical spreading characteristics of the wavefield, and is an effective way to discretise explicitly small-diameter boreholes. Numerical experiments show that the existence of a water-filled borehole can give rise to a strong waveguide effect which affects the transmitted waveform, and that excitation of this waveguide effect depends on the diameter of the borehole and the length of the antenna.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3056-3068
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• 1996

This papre presents the RDM algorithm for composition of bit. After this, we propose a digital signature scheme for facsimile document using RDM algorithm. We modify the even-odd feature in distance of changing pel between coding line and multiple reference line which have been scanned before, and run-length in coding line. The time to take in signature is reduced by spreading of signature. Non-repudiation in origin, the 3rd condition of digital signature is realized by proposed digital signature scheme. The transmitter embeds the signature secretly and tensfers it, and the receiver makes a check of any forgery on the signature and the document. This scheme is compatible with the ITU-T.4(G3 or G4 facsimile standard). The total amount of data transmitted and the quality of image are about the same to that of the original document, thus a third party does not notics signature embeded on the document.

• Clean Technology
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• v.10 no.4
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• pp.177-187
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• 2004

Dry ice snow jet was produced by high-pressure expansion of liquid carbon dioxide and subsequent acceleration by carrier gas flow. Removal mechanism for coating was not so different from that for contaminating particles on the surface. The removal of coating was quantitatively described by Hutchings' equation. The two parameters obtained from the plot, were used to predict the removal rate or the specific coating area removed by a unit mass of carbon dioxide. Their values also enhanced the reliability of the experimental data and enabled the experimental errors corrected. Hutchings' plots obtained with various values of either stand-off distance or nozzle length tends to meet apparently at a single unique point at which the scar-size enlargement by focusing jet plume was balanced with that by spreading it.

• Journal of the Korean Society of Safety
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• v.30 no.6
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• pp.40-47
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• 2015

In this study, temperature characteristics and fire damage form were analyzed to investigate flame spreading form and fire probability from ignition sources subject to drivit component materials which is finishing material in architecture. Ignition sources were limited to a gas torch and exterior panel board fire, and the size of the sample was manufacture in 30 cm length ${\times}$ 50 cm height ${\times}$ 5cm thickness size. Marble (inner wall) + 3 mm drivit (outer wall), marble (inner wall) + 4 mm plaster stone (outer wall), sandwich panel + 3 mm driver bit (outer wall), sandwich panel + 3 mm driver bit + insulation (outer wall), and gypsum board (inner wall) + 3 mm drivit (outer wall) were prepared for the sample. As result of the research for temperature characteristics, large temperature difference by each material was shown in $218^{\circ}C{\sim}995^{\circ}C$ at 30 seconds and $501^{\circ}C{\sim}1078^{\circ}C$ at 300 seconds. Especially when the inner wall was a plaster board, lowest temperature of $501^{\circ}C$ was shown at 300 seconds and marble inner wall showed the following lowest temperature of $900^{\circ}C$. Temperature rising over $1000^{\circ}C$ was shown in other materials. Regarding fire damage form, drivit or gypsum board outer wall parts exposed to fire showed combustion and carbonization to show calcination(breaking phenomenon) and influence of heat exposure was higher as calcination became more severe.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1715-1720
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• 2016

In the upcoming 5-generation mobile communication system, various techniques for improving the power efficiency and spectral efficiency have been proposed. 5G mobile communication system also have been studied a lot of multi-carrier-based modulation techniques like the 4G mobile communication system. In this paper, we analyzed the conventional system structure of the Zero-tail DFT-s-OFDM and UW (Unique Word) -DFT-s-OFDM system based on DFT-s-OFDM system in these techniques. UW and zero are added and used each system, and CP is removed. the result of quality of systems for simulation, OOB(Out of Band) power of Zero-tail DFT-s-OFDM and UW-DFT-s-OFDM use the less time resource as long as CP length, also both systems are reduced about 11dB than DFT-s-OFDM system. In these result, Zero-tail DFT-s-OFDM and UW-DFT-s-OFDM system are more effective than DFT-s-OFDM system.

• Journal of Animal Environmental Science
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• v.16 no.2
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• pp.115-122
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• 2010

A major problem within the agricultural/farming community concerns the enormous amount of manure produced by livestock; one possible solution to this problem is to use the animal slurry as a liquid fertilizer. While there are several areas where this fertilizer could be used, one promising area of application is within chestnut tree fields. However, since most of these fields are located on slopes of varying grades and not on flat land, a different spread system is required. Generally, chemical fertilizer is spread in the chestnut field manually by hand; not only does this require a great deal of manpower it is also very difficult and hard work. In our lab experiment, we investigated the relationship between the amount of fertilizer spread and the length of pipe used at varying pressure levels. The hose in our system utilized PVC piping with evenly spaced holes for the fertilizer to dissipate. We initially found that the amount of spread was greatly reduced by reducing pipe pressure. While the difference of the amount of spread during fertilizing was not great, we did find that the reduction of the spread could be correlated to the frictional resistance of the inner lining of the pipe. Based on this, we hypothesized that an increase in pipe pressure would yield a consistent spread. Additionally, a similar outcome could be obtained by regulating the distance of the holes in the pipe and their diameter.

• Journal of Digital Convergence
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• v.11 no.3
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• pp.95-100
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• 2013

K-POP is getting population at the all over the world. K-POP is based on the hook song that made using repetitive lyrics and melody. The characteristics of the music is a bit simple and cheerful rhythm and melody easy to sing along, interesting lyrics and great dance skills. K-POP is spreading to various countries via various social networking services such as YouTube, Facebook, Twitter. K-POP dominated by the digital music market, showed a growing tendency to shorten the length of music, to create a music that can give a strong impression. And 60 second pre-listening function increased music used the chorus in the first part. But it was generated the result that made obscures the configuration of the music and the meaning of the lyrics. In this paper, we study the characteristics of K-POP music and will present three directions of the hook song music production. Finally, we compared to Kangnamstyle of Psy using the proposed three standards.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.6
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• pp.705-712
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• 2001

It is of great importance to represent the directional ocean waves in a laboratory basin for hydraulic model tests. The directional ocean waves can be expressed as a linear superposition of a large number of component waves with different frequencies and propagating directions. The aim of the study is to check the wave generating characteristics by serpent-type wave generating system in PKNU (Pukyong National University) which is composed of 10 piston-type wave generators. In the experiment, spatial variation of irregular wave heights and propagating angles are measured in the multi-directional wave maker basin. Target wave directional spectrum is reproduced in the area of multi-directional wave maker basin. The directional spreading of the generated waves varied spacially in the basin. They differed from target spectrum as the measurement point becomes far from the center line normal to the generator face, The effective generation area where that target can be reproduced is limited to the triangular area attached the generator face. According to the results, it is emphasized that the effective experiment area in the basin considered wave generator characteristics should be determined in consideration of experimental conditions including structural shapes, water depth, wave directionality etc.