• Journal of the Korean Society for Precision Engineering
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• v.31 no.4
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• pp.353-358
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• 2014

This paper reports a simple, yet effective 1-step surface modification method for stainless steel. Electrochemical etching in dilute Aqua Regia forms hierarchical micro and nanoscale structure on the surface. The surface becomes highly hydrophobic (${\sim}150^{\circ}$) as a result of the etching in terms of static contact angle (CA). However the liquid drops easily pinned on the surface because of high contact angle hysteresis (CAH), which is called a "petal effect": The petal effect occur because of gap between surface microstructures, despite of intrinsic hydrophobicity of the base material. The pore size and period of surface structure can be controlled by applied voltage during the etching. This method can be applied to wide variety of industrial demand for surface modification, while maintaining the advantageous anti-corrosion property of stainless steel.

• Microbiology and Biotechnology Letters
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• v.28 no.6
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• pp.367-371
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• 2000

In order to develop a Korean traditional liquor using dandelion, alcohol fermentation condition was investigated. Etha-nol was produced maximally when 10% dandelion and 5% nuruk were added in cooked rice and fermented by S. cerevisiae at $25^{\circ}C$ for 10 days. The taste and nutraceutical properties of dandelion liquor with different concentra-tions(1%, 5%, 10%) of dandelion petal were compared. The dandelion-petal liquors which was brewed by addition of 1% dandelion petals into mash showed the best acceptability and its angiotensin-converting enzyme inhibitory activity was also high.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2002.04a
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• pp.55-56
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• 2002

노즐로부터 방출되는 초음속 제트유동의 특성은 노즐의 공급압력과 배압의 비에 따라 결정된다 노즐 배압에 상대적인 노즐 출구면에서 발생하는 압력의 크기에 따라 제트 유동은 과팽창, 적정팽창, 그리고 부족팽창의 형태로 된다. 종래 주로 단면이 원형인 초음속 노즐로부터 방출되는 자유제트에 관하여 많은 연구가 수행되어, 제트 유동의 특성이 비교적 잘 알려져 있다. 이들 연구 결과에 의하면, 제트 내부에서 발생하는 충격파 시스템은 노즐 출구면에서 유동의 팽창상태에 의존하게 되며, 제트 유동은 주위의 기체를 흔입(entrainment)하여, 유동의 하류방향으로 제트 폭이 확대되며, 유속은 감소하게 된다.

• Transactions of Materials Processing
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• v.10 no.6
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• pp.465-470
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• 2001

Hole flanging experiments are performed on flat circular plates with a hole in the center and the flangeability and fracture behaviors of TRIP steels and ferrite-Bainite duplex steels were examined. In the hole flanging, deformation by lip and petalling occurs when plates are struck by punches of various shapes and high circumferential strains induced in the target material cause radial cracking and the subsequent rotation of the affected plate material in a number of symmetric petals. In all cases, failure of the plate was due to lip fracture that results from multiple localized neckings that take place around the hole periphery where straining is most severe and a somewhat regular pattern was observed in a fracture shape. The neck characteristics in flange formation and the transition from the lip to petal mode at which fracture occurs were compared with two materials.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.19-22
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• 2003

Ejector-diffuser system is one of fluid machinery which can entrain the fluid in low pressure part and transport it to the higher pressure part. The conventional ejector-diffuser system has been pointed out that its overall efficiency is quite low compared with other fluid machinery since it is derived by only the pure shear stresses. In the present study, 4, 6, and 8 lobed petal nozzles with a design Mach number of 1.7 are adopted as a primary nozzle to improve the performance, and are compared with a conventional circular nozzle.

• Journal of Plant Biology
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• v.29 no.1
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• pp.19-40
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• 1986

A study on the species description, enumeration and interspecific relationships of genus Filipendula was undertaken for four Korean and two Japanese species. The use of scanning electron miroscope(SEM) has made possible a detailed study of foliar trichomes, pollen grains and fruit surface features. A new method for the preparation of SEM samples was developed in this study. Filipendula glaberrima, F. formosa, and F. korean were reliable endemic species. Among them, F. glaberrima shares many characteristics with F. formosa. F. gloaberrima can be divided into tow types based on leaf, seed, flower and pollen characters. Type I is characterized by ciliated fruits, many branched vascular bundles on the petal, dense trichomes on the leaf vein of abaxial surface, and many foveolate pollen surface. Type II possesses glabrous fruits, a few vascular bundles on the petal, rare trichomes on the leaf vein and a few foveolate pollen surface. The significant taxonomic characteristics in the classification of genus Filipendula are their lengths of fruit stalks, the densities of marginal trichomes of fruits, and textures of stipules.

• Animal cells and systems
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• v.9 no.3
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• pp.127-133
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• 2005

We investigated expression of cucumber senescence-associated genes (SAGs) from developing cotyledons and flower petals. Several cucumber SAGs have been reported in earlier reports. This is an extension of the previous findings. Semi-quantitative RT-PCR revealed that most of the cucumber SAG transcripts were consistently produced until the organ senescence. These results imply that many cucumber senescence-related genes are still active during the final development stage, playing some executive biological roles, possibly in remobilization of nutrients to the other parts of tissues or organs. These results were used to search for possible functions of senescence-related genes during organ development.

• Current Research on Agriculture and Life Sciences
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• v.32 no.4
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• pp.175-177
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• 2014

This is the first report describing the seasonal conditions affecting shoot regeneration by the chrysanthemum cv. Baeksun. The shoot regeneration from petal explants was found to be more favorable from September to December, reaching the highest values in December. In addition, the quality of the shoots was also influenced according to the season of the explant collection, where healthy and uniform plants were derived from the explants collected in December. Choosing the proper season for explant collection affected the successive plant growth parameters (i.e., plant height and fresh weight). Thus, the current results strongly suggest that season plays an important role in plant tissue culturing, which is an essential tool for micropropagation and Agro-bacterium-mediated genetic transformation studies.

• Korean Journal of Environmental Biology
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• v.40 no.2
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• pp.157-163
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• 2022

We analyzed the hair microstructure of Korean small terrestrial mammals, such as Rodentia and Lagomorpha, to classify the characteristics of hair morphology. Micromys minutus showed a unicellular irregular type of medulla structures; on the other hand, the other mammals showed multicellular structures. Regarding the cuticular scale structures, the Rodentia species exhibited a narrow and broad diamond petal type, while the Lagomorpha species exhibited an elongated petal type. Interestingly, the hair cross-sections showed quite unique characteristics. We constructed hair identification keys to distinguish species with a single hair. The dichotomous key of Rodentia and Lagomorpha can be used for their behavioral ecology and dietary analysis of upper predators to serve as the basis for ecological research.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2003.10a
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• pp.128-128
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• 2003