• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.6
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• pp.2005-2021
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• 2014

This paper proposes a novel image authentication scheme, aiming at tampering detection for block truncation coding (BTC) compressed image. The authentication code is generated by using the random number generator with a seed, and the size of the authentication code is based on the user's requirement, with each BTC-compressed image block being used to carry the authentication code using the data hiding method. In the proposed scheme, to obtain a high-quality embedded image, a reference table is used when the authentication code is embedded. The experimental results demonstrate that the proposed scheme achieves high-quality embedded images and guarantees the capability of tamper detection.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.6
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• pp.499-506
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• 1993

The contents of sulfur, sulfur-containing protein and amino acids of soybean seeds of 518 genotypes as well as their inheritance and selection efficiency in early breeding generation were measured to facilitate breeding for soybean with high sulfur-containing amino acids. Average seed sulfur content of 518 cultivars was 0.33%, and ranged from 0.20 to 0.45%, and that of 30 wild soybeans was 0.35%, and ranged form 0.19 to 0.62%. Correlation coefficients between seed sulfur content and sulfur-containing protein and amino acids were 0.924$^{**}$ and 0.974$^{**}$, respectively. Seed sulfur content was tended to be high in soybean genotypes with late maturity, seed coat bloom, or green cotyledon. Sulfur content had -0.312$^{**}$ correlation coeficient with sugar content and -0.384$^{**}$ with 100 seed weight. Seed sulfur content was inherited quantitatively, in which additive effect was greater than dominant one, and proportion of genes with positive effects was similar to those with negative ones. Estimated narrow- and broad-sense heritabilities were 0.75 and 0.88 for seed sulfur content, respectively. Heritability measured from selection in early breeding lines for high or low seed sulfur content was 60～62.5% or 50～62,5%, respectively. And selection for high sulfur content increased by 14.7～18.8%, whereas that for low one decreased by 8.8～15.6%, when compared to that of random population. Therefore selection in early generation seemed to be clearly effective.

• Korean Journal of Optics and Photonics
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• v.32 no.3
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• pp.120-125
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• 2021

We have developed a linearly polarized high-power Yb-doped fiber laser in the master oscillator power amplifier (MOPA) scheme for efficient spectral beam combining. We modulated the phase of the seed laser by pseudo-random binary sequence (PRBS), with the bit length optimized to suppress stimulated Brillouin scattering (SBS), and subsequently amplified seed power in a 3-stage amplifier system. We have constructed by coiling the polarization-maintaining (PM) Yb-doped fiber, with core and cladding diameters of 20 ㎛ and 400 ㎛ respectively, to a diameter of 9-12 cm for suppression of the mode instability (MI). Finally, we obtained an output power of 1.004 kW with a slope efficiency of 83.7% in the main amplification stage. The beam quality factor M² and the polarization extinction ratio (PER) were measured to be 1.12 and 21.5 dB respectively. Furthermore, the peak-intensity difference between the Rayleigh signal and SBS signal was observed to be 2.36 dB in the backward spectra, indicating that SBS is successfully suppressed. In addition, it can be expected that the MI does not occur because not only there is no decrease in slope efficiency, but also the beam quality for each amplified output is maintained.

• Fisheries and Aquatic Sciences
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• v.2 no.1
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• pp.98-104
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• 1999

The characteristics of the populations of shortnecked clam (Ruditapes philipinarum) originated from three different seed-production sites, Hadong, Kochang and Ulsan along the coast of Korea, were analysed by the morphological differences and the random amplified polymorphic DNA (RAPD) profiles. The morphology of the shell and survival rate for each population were also investigated 13-months after transplantation to a farming site in Shinsung. The morphology of the populations from Hadong and Kochang showed significant differences (P<0.05), but one year after transplantation to Shinsung, the morphology of these three populations was no longer significantly different (P>0.05). The template DNA for RAPD was efficiently extracted from the digestive diverticula of the clams. Up to 13 of amplified fragments were detected using arbitrary primers. Within the species of R. philipinarum, the genetic similarities ranged from 0.196 to 0.259. The populations from Hadong and Ulsan showed the highest similarity. The survival rates of the populations from Hadong $(69.4\%)$ and Ulsan $(63.8\%)$ were higher than that from Kochang $(41.7\%)$ 13-months after transplantation. From the RAPD analysis, it could be used as one of the primary criterion in determining which shellfish populations among various seed-production sites tend to be genetically similar and more adaptable and transplantable to a farming site.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.622-622
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• 2013

Piezoelectric energy harvesting (PEH) device refers to a power device for acquiring mechanical energy from the environment surrounding us which would otherwise be wasted and for converting it into usable electrical energy. While much work has been done on developing ZnO nanogenerator (NG) with nanowire arrays, there are some issues of not only scaling up its output power but also optimizing structure for operating feasibly in various conditions. Efficiency of NG is highly dependent on fixed orientation. But in many cases, it is not easy to predict where the pressure and vibration may come from. Furthermore, the direction of the applied mechanical stress is usually non-stationary and can be random in various practical applications. Therefore an omnidirectional PEH is needed.In this work, we investigate an omnidirectional PEH device consisting ZnO nanowires. We deposited spiral patterned ZnO seed layer on Kapton film. We deposited thin Cr layer on the ZnO seed layer using DC-sputter to form a passivation layer to retard un-expected growth of ZnO nanowires. We grew ZnO nanowires along the spiral arms using hydrothermal method. ZnO nanowires have been selectively grown from the ZnO sidewall without Cr layer and have the average length of$5{\mu}m$ and the average diameter of 40nm. We reduced the defect in the as-grown ZnO nanowires by O2 plasma using asher and by thermal treatment using RTA. Consequently, each nanowire has different directions to each other. This isotropic design can lead to the omnidirectional power generation. The morphology of NG is characterized with FESEM. Maximum output power of the device is measured by using a picoammeter and a nanovoltmeter.

• Convergence Security Journal
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• v.18 no.4
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• pp.27-33
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• 2018

Stream cipher is an one-time-pad type encryption algorithm that encrypt plaintext using simple operation such as XOR with random stream of bits (or characters) as symmetric key and its security depends on the randomness of used stream. Therefore we can design more secure stream cipher algorithm by using mathematical analysis of the stream such as period, linear complexity, non-linearity, correlation-immunity, etc. The key stream in stream cipher is generated in linear feedback shift register(LFSR) having characteristic polynomial. The primitive polynomial is the characteristic polynomial which has the best security property. It is used widely not only in stream cipher but also in SEED, a block cipher using 8-degree primitive polynomial, and in Chor-Rivest(CR) cipher, a public-key cryptosystem using 24-degree primitive polynomial. In this paper we present the concept and various properties of primitive polynomials in Galois field and prove the theorem finding the number of irreducible polynomials and primitive polynomials over $F_p$ when p is larger than 2. This kind of research can be the foundation of finding primitive polynomials of higher security and developing new cipher algorithms using them.

• Journal of Ecology and Environment
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• v.35 no.1
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• pp.27-34
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• 2012

Typha angustifolia has ecological characteristics of clonal growth similar to Phragmites australis. The plant spreads byclonal growth and seed dispersal. In this study, for the three stands which have different settlement age at the Baksilji wetland in Korea, genetic diversity was estimated by random amplification of polymorphic DNA analysis to evaluate the change in genetic diversity of T. angustifolia during stand development in the same population. Stand (ST) 1 was the oldest and ST 4 was the youngest. ST 5 was in a small ditch out of the Baksilji. Although the ST 1, ST 2, and ST 3 did not differ significantly in vegetational or physical environment, the genetic diversity estimated according to Nei's gene diversity (h) and the Shannon index (i) increased in the order of ST 1 < ST 2 < ST 3 contrary to formative age. The genetic diversity of ST 4 was much higher than that of the other three stands. ST 4 has similar abiotic environmental conditions with slight T. angustifolia dominance, and seems to be in the early establishment stage. ST 5 differed from the other stands in vegetational and soil environments, which can result in stressful cattail conditions. Even though the ST 5 stand was not younger than the ST 4 stand, ST 5 showed the highest genetic diversity. Our results indicate that after early settlement of the T. angustifolia population, genetic diversity within the species decreased over time and that the decreasing pattern of genetic diversity within T. angustifolia stands is not likely to occur under stressful conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.2
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• pp.180-186
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• 1994

Lipoxygenase activity of soybean seeds of approximately 507 genotypes as well as its inheritance and selection efficiency in early breeding generation was measured in the Department of Agronomy, Seoul National University to facilitate breeding for low lipoxygenase activity of soybean. Average seed lipoxygenase activity of 507 cultivars and strains was 350 unit (unit: $\Delta$0.01 /min. /mg at 234nm) and ranged from 50 to 670 unit. There was no difference in mean lipoxygenase activity according to apparent seed characters such as seed coat and embryo color. But early mature soybean genotypes had fairly low lipoxygenase activity. Lipoxygenase activity was inherited quantitatively, in which additive effect was greater than dominant one and proportion of gene with positive effects was similar to that with negative ones. Estimated narrow- and broad-sense heritabilities were 0.78 and 0.86 for lipoxygenase activity, respectively. Heritability measured from selection in early breeding lines for high or low lipoxygenase activity was 64~76% or 54~62%, respectively. And selection for high lipoxygenase activity increased by 29.7~44.7%, whereas that for low ones decreased by 21.8~27.3%, respectively, when compared to random population. Clear effect in selecting of lipoxygenase activity was present in early generation.

• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.577-589
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• 2021

Soil seed bank community contributes to the long-term conservation of plant diversity and vegetation dynamics, and their decreasing diversity and density with soil depth provide critical perspectives (deterministic and stochastic) for understanding the community disassembly process. We analyzed changes in species composition and diversity and structuring patterns by soil layer (top and bottom), including surface vegetation, in Gwangneung Forest, a mature forest with a vegetation climate in the temperate central part of the Korean Peninsula. From two layers of soil collected with a vertical difference of 10 cm, 934 specimens of 27 families, 40 genera, 44 species, three varieties, and 47 taxa, germinated. Although species diversity and germination density decreased in most comparative characteristics, including growth type, there was no statistical significance due to large deviations. Within-group variability of species composition was similar in the upper and lower soils, as was the decline pattern in co-occurred species (ζ-diversity) and change in species retention probability. The structuring process of the community composition in the two soil layers was fitted with an exponential correlation rather than a power function, demonstrating the dominance of the stochastic process. The pattern in diversity and species turnover according to soil depth in Gwangneung Forest was discovered to be structured by stochastic random events, such as seed vertical movement rather than interaction with trait characteristics.

• Asian Journal of Turfgrass Science
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• v.11 no.1
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• pp.73-85
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• 1997

Although zoysia grass (Zoysia spp.) has a lot of excellent chracteristics as warm-season grass, it have been limited in use due to slow establishment, low seed production, poor shade tolerance and other factors. Breeding trials have been continued from 1900's, much attentions have been paid especially in U.S.A., Korea and Japan recently. In U.S.A., more than 24 varieties had been evaluated at National Turfgrass Evaluation Program(NTEP) from 1991 to 1995 and some were regsistered as commercial. After the 6th International Turfgrass Research Conference at Japan in 1989, Japan Turfgrass In-corporation (JTI) sponsored by private companies and government carried out breeding programs for pest, salt, and shade tolerant and herbicide resistant varieties. JTI also has been trying to im-prove vigor and breed evergreen zoysia Korean breeders collected germplasms since 1960's. After USDA breeders came to Korean penesula in 1982, Korean breeders joined with USDA zoysia breeding project for several years. Many interspecific hybrids and natural selected varieties were breeded that period both in U.S.A and Korea. Breeding objectives were to extend green color period, improve leaf quality and density, and better leaf color at dormant stage. Since 1990's, zoysia grass breeding trials are getting more diverse in many points such as random amplified polymorphic DNA (RAPD) assay for ecotype identification. The objectives of this study are to evaluate germplasms in Korea, and also review the present status and future prospect in zoysia grass breeding in the world.