• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.12 no.1
• /
• pp.83-91
• /
• 2019

In this paper, we have effectively used the surface characteristics and local similarity existing in image, solved the problem that there is no CZP(Closest Zero point) that occurs in a very few images to hide secrete data into cover image by using histogram shift. By applying the proposed technique, it is possible to hide secrete data invisibly into the cover image, extract secrete data from the stego-image with no data loss, and completely restore the original cover image. It is impossible to know whether the secrete data is hidden in the stego-image because the stego-image constructed by applying the proposed technique has a good visual quality that can not distinguish the difference from the cover image. The proposed method is able to hide secrete data at various levels compared to conventional APD(Adjacent Pixel Difference) technique, and hide secrete data up to 25.1% more than APD in cover image.

• The Bulletin of The Korean Astronomical Society
• /
• v.46 no.1
• /
• pp.57.2-57.2
• /
• 2021

Variability in Young Stellar Objects (YSOs) can be caused by time-dependent accretion rates, geometric changes in the circumstellar disks, the stochastic hydromagnetic interactions between stellar surfaces and inner disk edges, reconnections within the stellar magnetosphere, and hot/cold spots on stellar surfaces. We uncover ~1400 variables from a sample of ~5300 YSOs in nearby low-mass star-forming regions using mid-IR light curves obtained from the 5.5-years NEOWISE All Sky Survey. The mid-IR variability traces a wide range of dynamical, physical, and geometrical phenomenon. We classify six types of YSO variability based on their light curves: secular variability (Linear, Curved, Periodic) and stochastic variability (Burst, Drop, Irregular). YSOs in earlier evolutionary stages have higher fractions of variables at all types and higher amplitudes for the variability. Along with brightness variability, we also find a diverse range of secular color variations, which can be attributed to a competitive interplay between the variable accretion luminosity of the central source and the variable extinction by material associated with the accretion process. We compare the variability of known FUors/EXors and VeLLOs/LLSs, which represent two extreme ends (burst versus quiescent) of the episodic accretion process; FUors/EXors have a higher fraction of variables (65%) than VeLLOs/LLSs (41%). Short-term (few day) and long-term (decades) variability, as well as possible AGB contamination in the YSO catalogues, are also discussed.molecules become more complex by surface chemistry induced directly by high energy photons or by the thermal energy diffused over heated grain surface. Therefore, the ice composition is an

• The Korean Journal of Mycology
• /
• v.30 no.2
• /
• pp.173-175
• /
• 2002

Sooty leaf blight was found on Dendrobium sp. in several farmers' fields located in Namji-eup, Changnyeong-gun, Gyeongnam province, Korea in 2001. Symptoms of the disease appeared on leaves. Sooty leaf spots were started with amphigenous, subeircular to irregular spots, with light grayish brown to black color with definite margin lines on the upper surface of leaves. Infected leaves became defoliated and whole plants eventually were died. The infection rates of the disease in the surveyed area reached up to 64.8%, in the early September. Conidiophores of the causal fungus were dark grayish brown in color, densely fasciculate, straight, curved to sinuous, branched, $5{\sim}10$ septate and $63{\sim}164{\times}3.2{\sim}4.9{\mu}m$ in size. Conidia were pale to olivaceous in color, obclavatecylindric, straight to slightly curved in shape, $1{\sim}5$ septate and $46{\sim}98{\times}3.2{\sim}3.9{\mu}m$ in size. The optimum temperature for mycelial growth of the fungus was $25^{\circ}C$. The fungus was identified as Pseudocercospora dendrobii on the basis of its mycological characteristics. This is the first report on sooty leaf light of Dendrobium sp. caused by Pseudocercospora dendrobii in Korea.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.30 no.4
• /
• pp.562-573
• /
• 1997

Comparative osteology of Chromis notata, C. analis and C. fumea was studied based on the samples collected from the Korean waters. The three species are distinguished by the shape of cranium, visceral skeleton, vertebra and caudal skeleton. Chromis notata has a glossohyal which is slightly curved in shape while two other species are deeply curved. C. analis has three spiniform procurrent caudal rays while others have two. C. fumes could be distinguished easily by the shape of preopercle which is serrate in posterior margin. This investigator reveals following bones as new taxonomic criteria for the genus Chromis in Korea. In cranium, height of supraoccipital, height of process of parasphenoid and anterior margin of basisphenoid, in visceral skeleton, presence of fine papilla-like process at the surface of preopercular sensory canal, in orbital bone, width of preorbital, in hyoid arch, shape of glossohyal, union state between lower hypohyal and ceratohyal and union state between ceratohyal and epihyal, in shoulder girdle bone, dorsal margin of posttemporal, width of upper postclavicle, posterior end of lower postclavicle and posterior margin of first actinost bone, in vertebrae, beginning point of parapophysis, in caudal skeleton, upper shape of second neural spine of pleural centrum.

• Journal of Korean Society of Environmental Engineers
• /
• v.37 no.2
• /
• pp.120-125
• /
• 2015

With rapid urbanization, the volume of traffic in urban area has been significantly increased. This in turn led to problem which can be described as Road Traffic Noise. Currently, to alleviate the road traffic noise damage, a demand for installation of soundproofing walls is rising. Among different shapes of soundproof walls being installed, the reflection-type acoustical insulation panel is highly drawing attentions of residents due to the fact that it does not obstruct their field of vision in contrast with the opaque acoustical insulation panel. On the other hand, improving the soundproofing wall of the reflection-type acoustical insulation barrier panel needs to be focused on since it has a possibility to cause a secondary damage by reflected sounds. Therefore, in this research, study has been carried out to improve the forms in order to minimize travelling of reflected sounds through changing the frontal surface shape and geometrical shape of the reflection-type soundproofing panel. A result from comparison between the normal reflection-type soundproofing panel and the improved soundproofing panel, with reduction effects in the noise reflection, showed that the curved type of soundproofing panel has an impact on reducing the noise up to 1.5 dB. Furthermore, from the research conducted, it appears that the increase and decrease in the reflected sounds can be changeable depending on various design factors. Thus, it turns out that the study shows a potential possibility to develop a reduction technology of the reflected sounds pertaining to overall condition on the soundproofing walls.

• Water for future
• /
• v.14 no.1
• /
• pp.39-49
• /
• 1981

The purpose of this study is to examine the meander charactericstics for the rivers in Korea..In this study, the new characteristics factors of meander are proposed, and the relationships among the factors proposed in this study and the existing factors are derived. An attempt is made to find considerable relation among meander characteristics, but width and meander belt did not show any defined trend and considerable scatter of points was observed. Relationships among the meander length, belt and flowrate, etc., which are factors of meander characteristics, are analyzed the 67 rivers above 30km in length. Channel shape factor which is the ratio of the length from the starting point to the end to the channel lenght, tortuosity which is the ratio of the curved channel length against the channel length are suggested for a new characteristics factor of meander. They are well correlated with channel length, Horton's shape facotr and meander gradient, consequently have to be important measures of river meander. The result of the detailed comparison and the analysis of degree of sinuosity, velocity and water surface slop are brought light on the fact show that the curved reach is morestable than the straight one. The ratio of the meander length to the meander belt and its accumulative frequency showed excellent correlationship when plotted on the semi-log paper. The results of regression analysis of meander belt and meander length show linear for the South Han river branches and power curve for the Geum river and the Nakdong river branches.

• Korean Journal of Plant Taxonomy
• /
• v.43 no.2
• /
• pp.118-127
• /
• 2013

A comparative study of leaf epidermal microstructure in tribes Forsythieae (Abeliophyllum: 1 species, Forsythia: 12 taxa - 10 species, 2 varieties), Fontanesieae (Fontanesia: 2 species) including one related genus Myxopyrum belonging to Myxopyreae (Myxopyrum: 5 taxa - 4 species, 1 subspecies) was carried out using scanning electron microscopy (SEM) in order to evaluate their significance in the taxonomy. The leaves of investigated taxa are either hypostomatic or amphistomatic, but former is more frequent. The size range of the guard cells is 17.14-47.58 ${\times}$ 11.59- 44.25 ${\mu}m$: the smallest one was found in Forsythia giraldiana (17.48-22.96 ${\times}$ 11.64-12.88 ${\mu}m$), while the largest one was measured to Myxopyrum pierrei (31.50-41.75 ${\times}$ 32.53-44.25 ${\mu}m$). Anomocytic stomatal complex are most frequent type (rarely paracytic), usually both anomocytic and anisocytic occur in one leaf. In surface view both adaxial and abaxial anticlinal walls of the subsidiary cells are variable (e.g., straight/curved, undulate, sinuate, undulate/sinuate). Three types (simple unicellular and multicellular non-glandular, subsessile glandular) of trichomes are found in leaves. Finally, the systematic significance of the leaf epidermal micromorphological characters in idenfitication and elucidation of these tribe, between or within the genera including among the species is also briefly discussed.

• Journal of the Korean Society of Radiology
• /
• v.11 no.7
• /
• pp.611-617
• /
• 2017

In this study, it was expected that long-term stability against external mechanical external force could be secured if the phosphor layer had ductility. In this study, a bendable $Gd_2O_2S:Tb$ sensitized paper was fabricated by screen printing method and the image uniformity was evaluated through RMS analysis and histogram analysis to investigate the effect of fatigue accumulation due to long-term external force and repetitive external force. As a result, the dominant pixel area is maintained constant and the relative standard deviation is less than 10% for the long-term external force. However, for the repetitive external force, the dominant pixel area is divided into three areas and the image uniformity is adversely affected. Based on these results, it is suggested that the curved surface detector can be applied by securing the mechanical stability against the existing radiation sensitized paper. However, further studies are needed to apply it to the flexible detector. As a result, flexible radiation sensitizers can be applied to various curved surfaces, and it is expected to be applicable to various fields such as nuclear medicine, medical treatment, and industrial fields in the future.

• International Journal of Highway Engineering
• /
• v.14 no.1
• /
• pp.95-102
• /
• 2012

This study has been conducted to characterize the relations between the accident rate and the overlap section elements where the horizontal alignment and vertical alignment are overlapped. The researches were performed on Horizontal curve sections of 4-lane highways with 100km/h of design speed and speed limit. Korea Highway Corporation's Geographic Figurative Information System was adopted for geometric organization and Highway Traffic Accident Statistics was used. The results reveal that sections made of a single slope without vertical curve has greater accident rate than those with vertical curve, and that sections with 1 vertical curve are higher in the accident rate than those with over 2 vertical curve. For the sections with 1 vertical curve, SAG sections are higher than CREST sections and for the previous straight section of horizontal curve are higher than curved ones. In particular, when the road surface is wet, the accident rate is closely related with SAG vertical curves or leftward horizontal curved sections. This study will have meanings that it proposes the importance of design of road alignment by taking consideration of 3D synthetic alignment conditions for improvement of the road safety.

• Archives of design research
• /
• v.15 no.1
• /
• pp.181-190
• /
• 2002

Every object's patterns is the balancing-relationship between the object's inner-energy and outer-stress. To see this as a balancing-relationship between an organism, inner-energy would be the occurrence of thermodynamic entropy which is for its existing maintenance. Outer-stress would be the friction that comes from the surrounding environment. Namely, we can see that object's figure exists in the balance between an extort to survive and fiction that disturb it. However, it is fourth that these figures are consisted of a curve and curved-surface which is not a straight line. So, it is impossible to find a figure made up of straight lines and surfaces in the existing object's world. It's true that we have regarded only a curve as the beautiful. Here, we have presented that in a curve, there exists an important function which protect our survival from the ancient humanity. And by closely observing the function in a physical dynamic-pattern sight, we've searched what is important in the design's origin that handle curve-patterns. Of course it would be more reasonable to analyze it in the standpoint of Mathematics, Chemistry, or Biology, and synthesize the points. However, due to the limitation of the researchability, we will concern about the physical structure in the design. Deficient details will be replenished through the study between educational systems. As a result, we have confirmed that, devoting the curve's physical structure-phenomenon (occurred in nature) to the design, is more beautiful in our eyes, too.