• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.11
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• pp.5673-5691
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• 2019

Information centric mobile network can significantly improve the data retrieving efficiency by caching contents at mobile edge. However, the cache pollution attack can affect the data obtaining process severely by requiring unpopular contents deliberately. To tackle the problem, we design an algorithm of mitigating cache pollution attacks in information centric mobile network. Particularly, the content popularity distribution statistic is proposed to detect abnormal behavior. Then a probabilistic caching strategy based on abnormal behavior is applied to dynamically maintain the steady-state distribution for content visiting probability and achieve the purpose of defense. The experimental results show that the proposed scheme can achieve higher request hit ratio and smaller latency for false locality content pollution attack than the CacheShield approach and the baseline approach where no mitigation approach is applied.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.191-194
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• 2003

The purpose of this paper was to derive soil-water characteristic curve equation for unsaturated soil. To this end, a series of suction measured test was conducted on the selected 4 kinds of soil which is located in Korea, used the modified pressure plate apparatus. From the test results, it was proved that characteristic curve changes according to grain size distribution, size of void and fine grained soil contents. Residual degree of saturation(Sr) was decreased with void ratio and changed with fine grained soil contents, parameter ${\lambda}$ and hr was increased with void ratio. Soil-water characteristic curve equation based on the test result was suggested by void ratio or grain size distribution.

• Water for future
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• v.5 no.2
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• pp.30-43
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• 1972

The paper describes on the hydrologic analysis of point rainfall data of the three major areas, such as in Seoul, Pusan and Taegu. Scheme of the paper is analyzed five research cases. Contents of the analysis are carried out five kinds of transformed variables for determination of rainfall distribution types and two kinds of reliability tests on unusual(extraordinary) values each rainfall durations:short durations, long durations, long durations, monthly and yearly. Rainfall depth probability had been computed methods of hydrologic amounts analysis namely logarithmic transformations or Gumbel-Chow method and so on, but in this paper it is calculated log xi, n-square root transformations by using normal distribution function and normalization of rainfall distributions is examined graphical tests and $X^2-test$(chi-square test). Furthermore, rainfall depth probability is calculated taking into account the safty factors of project life of hydraulic structures. We think it is advanced contents that considering priceless experiences, the life of structures, conditions and more problems of planning engineers and designers, proposed rainfall amounts(proposed values) are presented charts or figures.

• The Journal of the Korea Contents Association
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• v.12 no.7
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• pp.445-452
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• 2012

This study is used to analyze the distribution of resistance factors and the relationships of flow resistance with the field measurements which consist of the total 2,604 rivers for 1,865 bed material in natural channels and 739 vegetation in vegetated channels. Resistance factor relationships and distribution range of Manning roughness coefficients and Darcy-Weisbach friction coefficients by the regression analysis are derived from the power law form as a function of flow discharge and friction slope with bed materials and vegetations in natural and vegetated rivers, respectively.

• The Journal of the Korea Contents Association
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• v.4 no.3
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• pp.53-60
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• 2004

In this paper we present user authentication and key distribution using threshold PKC(Public Key Cryptosystem), which is secure against the dictionary attack. The n servers hold a t-out-of-n sharing of the dealer's secret key. When the server authenticate a user, at least f of them cooperate they can reconstruct password verifier.

• YAKHAK HOEJI
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• v.29 no.4
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• pp.223-226
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• 1985

0.1%-Merthiolate solutions were applied to rats with or without sodium selenite. Rat organs were excised under ether anesthesia. Mercury contents in rat tissues were determined by quartz tube combustion gold amalgamation method. Mercury contents were accumulated at about 3-fold in the brain, 143-fold in the kidney, 62-fold in the blood cell, 22-fold in the liver than those of untreated rats respectively, on the 1st day after application of mert iolate for 7 days. On the other hand, the addition of sodium selenite caused a shift in the tissue mercury distribution. Our study showed that simultaneous administration of sodium selenite increased the accumulation of mercury in the brain, but became to decrease it after 9 days, while decreased it in the kidney, but grew to increase it, respectively.

• Journal of the Korean Wood Science and Technology
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• v.26 no.4
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• pp.34-42
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• 1998

Three hardwood (ash, alder and black locust) and three softwood (Japanese red pine, radiata pine and Western hemlock) specimens were dried in microwave(MlW) oven and their drying rates were obtained. Their specific permeabilities were also measured by using a modified liquid permeability measuring device. The correlation between the M/W drying rates and permeabilities of six species were statistically analyzed. It was revealed that within a species there is a logarithmic relationship between the M/W drying rates and average moisture contents and that among species there is a linear relationship between the M/W maximum drying rates and the average specific permeabilities. A exception was Western hemlock, which was of low permeability and of high drying rate. A Me-time equation, which showed a good agreement with the actual data, was derived. Thus using this equation the moisture contents of wood and the drying end points of M/W drying could be predicted. Infrared images of the thermal distribution in wood were illustrated.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06a
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• pp.674-679
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• 1994

Acoustic signal such as speech and scattered sound, are generally a nonstationary process whose frequency contents vary at any instant of time. For time-varying signal, whether a nonstationary or a deterministic transient signal, a traditional frequency domain representation does not reveal the contents of signal characteristics and may lead to erroneous results such as the loss of desired characteristics features or the mis-interpretation for a wrong conclusion. A time-frequency domain representation is needed to characterize such signatures. Pseudo Wigner-Ville distribution (PWVD) is ideally suited for portraying nonstationary signal time-frequency domain and carried out by adapting the fast Fourier transform algorithm. In this paper, the important properties of PWVD were investigated using both stationary and nonstationry signatures by numerical examples PWVD was applied to acoustic sigtnatures to demonstrate its application for time-ferquency domain analysis.

• Elastomers and Composites
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• v.31 no.1
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• pp.23-32
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• 1996

PVB was blended with PMMA in order to recycle scraped PVB material which recovered in the safety glass manufactories. The purpose of this research on PVB/PMMA blend was applied with excellent tackiness and transparency of PVB as a material of high strength to make the maximum use. Also, the blending of PVB with PMMA was aimed at the increase of impact strength of PMMA because the elastic property of PVB might decrease the brittleness of PMMA due to the lack of inner impact resistance. Izod impact resistance was propotional to increase the content of PVB, which was predominantly increased in the addition of 10phr above MBS. High rate impact resistance showed a tendency to Increase but it showed a tendency to decrease maximum load and energy if the contents of PVB increased. On the other hand total energy and ductile index showed a tendency to increase excellent impact resistance in the addition of MBS contents. As a result of observed surface of PVB/PMMA blends, the size of PVB domain increased distribution homogenuously, in the addited MBS contents increased it showed distribution homogeneously and partially a wetability.

• Journal of Korea Soil Environment Society
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• v.4 no.1
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• pp.35-47
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• 1999

Mine tailings, soils. stream sediments around Gubong disused mine were analyzed in order to investigate their distribution and pollution levels of heavy metals and cyanide. The average contents of As, Cd, Cu. Hg, Pb, Zn, and CN￣ in mine tailings were 6.93$\times$$10^{3}$, 56.9, 209, 5.03, 3.25$\times$$10^{3}$, 1.89$\times$$10^{3}$, 21mg/kg respectively. The pollution indices that calculated by the tolerance level of Kloke were 42~95 and the pH values were slightly alkaline in mine tailings. The contents of heavy metals and cyanide in field soils near the mine were higher than the paddy soils. The contents of heavy metals in the stream sediment were up to that of the tailings, so contamination from the mine tailings were serious.