• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.7
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• pp.97-104
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• 2006

The spray and breakup characteristics of swirling liquid sheet were investigated by measuring the spray angle and breakup length as the axial Weber number Wel was increased up to 1554 and the ambient gas pressure up to 4.0MPa. As Wel and ambient gas density increased, the disturbances on the annular liquid sheet surface were amplified by the increase of the aerodynamic forces, and thus the liquid sheet disintegrated near from the injector exit. The measured spray angles according to the ambient gas density were different before and after the sheet breaks. Before the liquid sheet breaks, the spray angle was almost constant, but once the liquid sheet started to breakup, the spray angle decreased. And the breakup length decreased because of the increase of the aerodynamic force as the ambient gas density and Wel increased. Lastly, the measured breakup length according to the ambient gas density and Wel was compared with the result by the linear instability theory. We found that the corrected linear instability theory considering the attenuation of sheet thickness agrees well with our experimental results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.949-952
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• 2017

Spray characteristics of the impinging injectors in subsonic crossflows were experimentally studied and compared with the plain-orifice injectors. By changing the impingement angle (60, 90, 120) which is the same orifice length to diameter ratio (L/d = 5), spray characteristics were investigated. In the view of the top view from the impinging injectors, as the impingement angle increases, the liquid column breakup length in the y-direction was decreased. On the other hand, when the impinging injector is viewed from the side view, the breakup length in the x direction is smaller than the previous plain-orifice injectors, which mean that the atomizing performance of the impingement-type injector is better than that of the single-hole orifice.

• Korean journal of communication and information
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• v.43
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• pp.314-358
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• 2008

This study examined how the meaning of news stories covering the split of national opinion was constructed in the media to represent social conflicts. To clarify the function of the term 'split of national opinion' as an ultimate term, this study examined the meaning of the term in the context of both text and society. Ten newspapers were included in the content analysis. The frequency of words used for the purpose of metaphor and equivalent in describing the split of national opinion was calculated to determine their meaning in the textual context. The frequency of incidents and subjects involved in allegedly causing the split of national opinion was calculated to determine their meaning in the social context. The results of this study are summarized as follows: First, the term 'split of national opinion' was coined by the newspapers as a metaphor of disease, disaster, and cost. The attitudes or the ways in which the split of national opinion was dealt with were generally negative and passive. Second, the term 'split of national opinion' was dealt with an equivalent status of such terms as national policy, national loss, societal problems, and ideology. Third, each newspaper reported that the split of national opinion had been caused by certain subjects, which indicates that each newspaper had its own position of viewing who was the key player in splitting the national opinion. The implication was also discussed that the use of the ultimate term would incur the unbalance of power between participants and the existing players, which would make individuals or groups who were involved in the social actions excluded and make the newspapers exercise the rhetorical power as news media.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.186-190
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• 2006

This study was performed to investigate the characteristics of a co-axial swirl injector. Especially to predict the initial liquid sheet thickness and spray cone angle of an outer orifice a concept of effective area was introduced from hydraulic analysis. In addition, the parameters determining the characteristics of a co-axial swirl injector were re-defined around outer orifice. The calculated results-SMD, spray cone angle, and spray thickness agreed well with the test results qualitatively.

• Journal of Plant Biology
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• v.28 no.2
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• pp.105-118
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• 1985

This study was carried out to investigate the epidermal structure and types of stomata on the upper and lower surfaces of the leaves in six species and one variety belonging to Korean Crassulaceae. The shape of epidermal cells was polygonal, isodiametric, or elongated. The cell wall was thick, sinuous or deeply sinuous. The subsidiary cell wall was thin or mostly arched. The cytolith-containing cells were found in Orostachys japonicus. The distribution of stomata was more on the upper surface than on the lower surface in the leaves of O. japonicus and Sedum sarmentosum. The stomata in the other species were less on the upper surface than on the lower surface, and stomatal size was different in each species. The great majority of stomatal types was the helico-eumesogenous type. This type was subdivided into two, parahelico-eumesogenous type and diahelico-eumesogenous type by us on the basis of the angle of division of guard mother cell and the long axis of the last-formed subsidiary cells. Sometimes allelo-eumesogenous type as well as aniso-eumesogenous type was found. The tetra-eumesogenous type with four mesogenous subsidiary cells was rarely observed. It was observed that the varieties of aniso-eumesogenous type with one to three subsidiary cells and one helix of subsidiary cells were developed by the secondary division of subsidiary cells of aniso-eumesogenous stoma. The compound shape of helico-eumesogenous stomata was found. Five new kinds of stomatal types were observed as follows; the helico-tetra-eumesogenous type, the coallelohelico-eumesogenous type, the cohelico-allelo-eumesogenous type, the duplotetra-eumesogenous type, and the aniso-euperigenous type. These types were reported here in the vascular plants for the first time.

• Applied Microscopy
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• v.33 no.2
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• pp.105-116
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• 2003

In Vitro fertilization of U. unicinctus eggs observed by immunofluorescence and electron microscopes revealed an overview of the meiotic pattern of the tide animals. The eggs have been fertilized early at germinal vesicle stage, followed by germinal vesicle break down (GVBD), but pre-mitotic aster like structure could not be resolved by the methods employed in this work. The meiotic features, such as rotation-shift movement of spindle fibers, behavior of spermatozoonmonaster in the egg cytoplasm and active spindle fiber of the 1st polar body, have been observed. The antitubulin-FITC fluorescence show the 2nd meiotic apparatus appeared firstly parallel to the tangential line of the oolemma, proceeding the meiosis, its bipolarity is rotated and shifted towards the oolemma. The polar bodysite of the oolemma was not amorphous, but active in a sense of anti-tubulin-FITC reactions during the extrusions of the polar bodies. The immunofluorescence reactions of the spermatozoon centriole appeared at a later stage of the 2nd meiosis. During the time periods, the fertilized spermatozoon resided in the egg cytoplasm. Activating the centrioles, spermatozoon approaches towards the chromosomal materials of the 2nd oocyte. This suggests that spermatozoon centrioles initiate and play a roll to fuse male and female pronuclei.

• Journal of Ginseng Research
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• v.24 no.4
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• pp.183-187
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• 2000

The present study was performed to evaluate the cytotoxicity of white and red ginseng extracts against cancer cells in vitro. We also examined the effects of those ginseng extracts on the cell cycle by using flow cytometry. We divided each white and red ginseng into two parts, main body and rhizome, and tested the cytotoxicity of each fraction against various mouse-originated cancer cells and mouse peritoneal macrophages. The red ginseng was more cytotoxic to the cancer cells in comparison with white ginseng, and the rhizome fractions were more cytotoxic than the mainbody fractions in the both of white and red ginseng. Among the cells tested, RAW264.7 cancer cells were most sensitive to all the ginseng fractions. In cell cycle analysis, all the fractions of white and red ginseng arrested the cell cycle at G$_2$/M phase.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.2 s.245
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• pp.161-169
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• 2006

The spray characteristics of liquid jet in cross flow with variation of injection angle are numerically studied. Numerical analysis was carried out using KIVA code, which was modified to be suitable for simulating liquid jet ejected into cross flow. Wave model and Kelvin-Helmholtz(KH)/Rayleigh-Taylor(RT) hybrid model were used for the purpose of analyzing liquid column, ligament, and the breakup of droplet. Numerical results were compared with experimental data in order to verify the reliability of the physical model. Liquid jet penetration length, volume flux, droplet velocity profile and SMD were obtained. Penetration length increases as flow velocity decreases and injection velocity increases. From the bottom wall, the SMD increases as vertical distance increases. Also the SMD decreases as injection angle increases.

• Journal of The Korean Association For Science Education
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• v.31 no.5
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• pp.680-693
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• 2011

In conceptual ecology, a concept does not exist independently but occupies an ecological niche in ecological environment. Among many biological concepts, genetic concepts are connected to several units including the genetics unit, and within the genetics unit the concepts of sub-areas are highly dependent on one another. For this reason, we analyzed conceptual diversity and conceptual proximity of genetic concepts through the ecological niche approach. For this purpose, we surveyed 995 9th graders. The areas covered in the survey were four genetic concepts: gene, chromosome, mitosis, and meiosis. The questionnaire presented biological concepts or terms related to each area, and the respondent marked the relevance between the presented biological concepts or terms and each area on a scale of 1~30 points. With 9th grade students, we analyzed the change of genetic concepts through class by the ecological niche approach. Through class, the total number of concepts increased in all of the areas, and the increase was smallest in the area of meiosis followed by mitosis, chromosome and gene. Relative density decreased with increases in the number of concepts. The conceptual diversity index also increased through class in all of the areas, and the increase was smallest in the area of meiosis followed by mitosis, chromosome and gene. In addition, difference in the relative density of concepts was reduced after class, and difference in the score of relevance was also reduced and consequently similarity among concepts increased. From these results were drawn conclusions as follows: First, through class, the conceptual diversity of genetic concepts increased. Second, through class, the conceptual proximity of genetic concepts increased.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.2
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• pp.1-10
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• 2018

This study investigated the acoustic forcing effects on the liquid column breakup length and the trajectory of liquid jets in crossflows. Cold-flow tests with a single hole circular nozzle injector were carried out by changing the injection pressure and acoustic forcing amplitude. Additionally, spray images were obtained at 12 phase angles to investigate the influence of the phage angle. The results revealed that the liquid column breakup lengths generally decreased under the acoustic forcing conditions, in comparison to those under the non-acoustic forcing conditions. However, they were not affected by the variation in the phase angles. On the contrary, it was found that the acoustic forcing hardly influenced the liquid column trajectories.