• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.1
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• pp.81-86
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• 1996

Silage wm(cv, Gwanganok) was cultivated during 1991-1994 on paddy land as a rotational cropping system of rice, to evaluate the effect of cattle manure application on the soil characteristics, yield performance and quality of com plant. The treatments used in this study were non-fertilizer, NPK standard in chemical fertilizer(N:$P_2O_5$ : $K_2O$= 200 : 150 : 150 kg/ha), cattle manure 20.40, 60 and 80 ton/ha Application of cattle manure improved soil pH, organic matter, available phosphate and exchangeable cations in the soils. During the experiment, soil pH was improved from 4.7 in the chemical fertilizer application(control) to 5.4-5.6 in the application of cattle manure, and available $P_2O_5$ wntent was increased from 72.2 ppm(contro1) to 340.2 ppm(cattle manure 80 ton/ha). Application of cattle manure increased plant growth, plant height and stalk diameter, and silage yields. Dry matter yields were produced 15.88 ton(chemical fertilizer), 20.11 ton(cattle manure 40 ton) and 21.22 ton/ha(cattle manure 80 ton/ha). However, no signicant yield differences were observed between cattle manure 40, 60 and 80 tonlha Productions of total digestible nutrients(TDN) and net energy for lactation(NEL) were also increased under cattle manure application. From the abobe results, the proper application amount of cattle manure was 40 tonha in this experiment.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1228-1231
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• 2002

Digital image watermarking scheme using adaptive block division is proposed. To increase the perceptual invisibility, the image is divided into blocks by local properties and the human visual system (HVS), then the significant blocks are selected in the divided blocks. The significant coefficient is determined by Weber's law in these blocks. To increase the robustness, low frequency domains of the discrete cosine transform (DCT) and the discrete wavelet transform (DWT) are used. The watermark is embedded into the selected significant blocks of the DCT's and DWT's low frequency domains with adaptive watermark strengths. The watermark strength is determined by the variance and the local properties of the significant block. The experimental results prove that the proposed scheme has a good robustness against several image processing operations (e.g. median filtering, cropping, scaling, JPEG, JPEG2000, etc.) without significant degradation of the watermarked image.

• Journal of Advanced Navigation Technology
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• v.10 no.4
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• pp.364-370
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• 2006

In this paper, the decision method of optimal sub-band which is supposed to embedded watermark incorporating fuzzy inference into transform-based watermarking is proposed. After performing the DCT, maximum variation of human visual properties, such as text degree, contrast sensitivity function is calculated, and by using these, membership function is generated. After embedding the watermark to the selected bands obtained from fuzzy inference, performance of imperceptibility and robustness are evaluated. In order to testify the proposed scheme, such attacks as JPEG, filtering, cropping are utilized. and in addition, by using an AWGN channel of OFDM/QPSK system, PSNR as well as correlation are calculated, and finally evaluated the performance.

• The KIPS Transactions:PartB
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• v.10B no.6
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• pp.629-638
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• 2003

In this paper, we propose an improved method of watermarking to increase the invisibility of a watermark and robustness against attacks for the purpose of removing the embedded watermark. The proposed method adaptively selects DCT blocks and determines position and intensity for watermarking based on the characteristics of human visual system. The used features are texture, luminance and contrast. We show the experimental results against image processing attacks such as cropping, image enhancement, low pass filtering, and JPEG compression, and then discuss the performance of the proposed method.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.2
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• pp.67-72
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• 2005

Overwintering capacity, closely related to winter hardiness, of Chinese milk vetch planted with different sowing times and sowing practices was investigated to improve the incorporation into cropping system in Korea. The tolerance to low temperature was evaluated with $LT_50$ using leaf disc leaching method. Dry weight of CMV was reduced remarkably with delayed planting from Sep. 5 to Oct. 20. The differences in tolerance to freezing temperature were not conspicuous among CMV genotypes, however, the differences between genotype (collections at different regions) were due to the plant architecture, mainly to the leaf angle. The crouching genotype collected at central region of Korean peninsula, which showed excellent freezing tolerant, has planophile leaves. The feature of internal constituents of CMV genotypes did not show any noticeable differences with respect to the freezing tolerance which evaluated by leaf disc leaching experiment. To overcome the poor overwintering capacity, tolerant genotype should be developed by selection with considering the plant architecture. The reduction of CMV growth during overwintering period was ameliorated with furrow-sowing under late-sown condition, therefore, when the CMV is inevitably sown late after recommended time, the seeds should be sown on furrow to overcome the cold stress.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.2
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• pp.97-101
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• 1999

No-till direct seeding cultivation of rice has major advantages such as saving of labor and cost by eliminating tillage, preparation of seed bed and trans-planting procedure compared to the conventional transplanting cultivation. A field experiment was conducted to evaluate the effects of straw treatment and nitrogen levels on the rice growth in no-till direct-seeding cultivation. Rice straw, vetch straw, and the mixture of both of the straws were mulched on the surface of soil before seeding while 4 levels of nitrogen fertilizer, 0, 7, 9, and 11 kkg/10a respectively, were applied at 3 split times, 3-weeks after sowing, 5-weeks after sowing and the panicle initiation stage. Mulching of vetch straw significantly reduced seedling establishment of rice which may be attributed to low oxidation-reduction potential of soil by vetch mulching treatment. Vetch straw increased the concentration of soil ammonium leading to an extension of the greenish leaf to panicle initiation stage. Agronomic nitrogen use efficiency (AD $E_{N}$) in heavy-mixed straw mulching plots was lower than other treatments. Grain yield and AU $E_{N}$ in the vetch treatment were less affected by fertilized N levels. Conclusively, it is suggested that heavy straw mulching was not efficient for rice seedling establishment and nitrogen usage.e.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.2
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• pp.102-105
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• 1999

Mineralization of organic N is an important factor in determining the appropriate rate of organic matter application to paddy fields. A kinetic analysis was conducted for nitrogen mineralization of rice, barley, Chinese milk Ovetch (Astragalus sinicus L.; MV) and narrow leaf vetch straw in paddy soil. Nitrogen immobilization occurred rapidly and its rate increased in straw with high C/N ratio. The amount of nitrogen mineralization was rapid in the first year of rice-vetch cropping system. The rate constant (K) depended on the C/N ratio of organic matter. Mineralization of straw increased at high temperature. The amount of available N increment resulted in fast mineralization of straw, especially in rice and barley straw. Chinese milk vetch had the greatest mineralization rate at all temperatures and fertilization levels followed by narrow-leaf vetch. However, rice and barley straws with high C/N ratio immobilized the soil N at the initial incubation duration. Chinese milk vetch or narrow leaf vetch was not effectively mineralized in mixed treatments with rice or barley straw. The mineralization rate of organic matter was mostly affected by the C/N ratio of straw and temperature of incubation. Organic matter with low C/N ratio should be recommended to avoid the immobilization of soil N and the increasing mineralization rate of straw.

• Magazine of the Korean Society of Agricultural Engineers
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• v.30 no.1
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• pp.31-37
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• 1988

This study, based on the monthly rainfall data, was carried out to determine the agricultural drought index which enables to describe the regional and seasonal drought characteristics of rice cropping system in Korea. The results obtained were summarized as follows ; 1.A new agricultural drought index (ADI) was evaluated seasonally according to the product of drought intensity and duration. This ADI is proposed as standard design criterion for irrigation planning. 2.The relationship between agricultural drought index and return periods was figured out. These diagrams could be used to estimate the seasonal drought severity of a certain year and to select design year corresponding to the specific drought frequency. 3.The regional drought characteristics were classified and those are useful to determine proper rice varieties and planting time and make drought counterplans. 4.Spring drought occurred once in 3 or 4 years and in a regional respect, rather frequently occurred in Seoul and Daegu areas than in Busan, Daejeon, Kwangju and Chuncheon areas. Summer drought occurred once in 5 years in Daegu and Busan areas and once in 7 or 8 years in other areas. 5.Sequential drought which gave severe drought damage of rice production occurred once in 20 years in Daegu area and in 10 years in Kwangju area.

• Research in Plant Disease
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• v.13 no.1
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• pp.1-5
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• 2007

Major diseases of tobacco and farmer's control practices were surveyed in the Kyeongbuk province area from 2005 to 2006. Mosaic caused by potato virus Y and bacterial wilt caused by Ralstonia solanacearum were most severe during the harvest season. Compared with the disease occurrence of ten years ago, the damage by tobacco mosaic virus reduced but bacterial wilt increased. These changes in the disease occurrences may probably be due to releasing the resistant tobacco cultivar to the mosaic virus but susceptible to the bacterial wilt pathogen. More than thirty percentage of the farmers have misused fungicides and also have applied the continuous mono-cropping system for more than ten years, and have chosen the incorrect crops for the rotation.

• Korean Journal of Microbiology
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• v.21 no.1
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• pp.7-14
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• 1983

In order to study the effects of cropping system and fungicide (Dachigaren) on soil microbes, the seasonal fluctuations of soil microbes in the fields of radish and Chinese cabbage including soil pH, Soil moisture content and soil temperature were investigated on every 15 day interval from the begining of March to late October in 1981. The population of total fungus peaked at the begining of July, while that of total bacteria, at the begining of August. They were affected by soil temperature, however pathogenic microbes seemed to be more related with host plants than the soil temperature, because pathogens showed high density through the whole cultivation period. The pathogenic microbes showed the density of order ; Xanthomonas, Erwinia, Pseudomonas, Agrobacterium and Corynebacterium. Xanthomonas, Erwinia and Pseudomonas, which induced radish and Chinese cabbage diseases were higher than Agrobacterium and Corynebacterium in population densigy. Bacterial soft rot occured at the density of Erwinia $5.9{\sim}6.6{\times}10^5/dry$ soil 1 gram. The density of microbes on continuous fields were higher than that of rotating fields, but there were no significant difference between treated fungicide plot and non treated in the density of microbes, also no difference between Chinese cabbage and radish growing fields.