• Journal of Korean Society for Atmospheric Environment
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• v.15 no.E
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• pp.73-79
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• 1999

To Characterize the single raindrops as a function of their size we designed the sampling and handling apparatuses. Samplings of single and size- classified raindrops were performed at a height of 20m above the ground level of a Kyoto University building located in Uji, Japan in rain events from middle of July to the end of August, 1999. And PIXE method was applied to the analysis of single raindrops sampled as a function of their size. Diameter change of frozen raindrops by liquid nitrogen did nto affect the size segregation ability of our sampling apparatus. The number of raindrops increases with decreasing drop size. And it is found that the size distribution of raindrops verified depends on the rain events. Application of PIXE analysis to the measurement of single raindrops was very successful. Every element showed a continuous increase in concentration with decreasing raindrop diameter. It seems reasonable to say that our work should be helpful to obtain more detailed information on single raindrops and especially to study on the rainout and washout mechanisms.

• Solar Energy
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• v.17 no.2
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• pp.3-11
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• 1997

In conventional heat and vent dryer, both sensible and latent heat could not be recovered from the exhaust air, but this problem could be solved by introducing a heat pump to a conventional dryer, having a connection with cooling, dehumidifying and heating of heat pump. In this work, HFC134a as a substitute refrigerant of CFC12 adopted in heat pump and a batch type is also introduced. The variables affected on the system performance are holding temperature of a drying chamber, bypass air ratio, degree of superheat and refrigerant flowrate, etc. The moisture contents were decreased curvilinearly in the range of $86{\sim}75%$ on the wet basis. Under the constant drying temperature, the face velocity plays an important role to the drying performance. The COPs are increased in accordance with the air velocity, on the other hand the SMERs are gradually decreased.

• Korean Journal of Community Nutrition
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• v.2 no.3
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• pp.396-405
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• 1997

We performed this study to understand the health status and food intake of North Koreans. Information was collected by individual closed in-depth interviews of 11 escapers from North Korea as well as books, newspapers and North Korean movies. Interviews were done from October, 1996 to May, 1997, covering their heights and weights, their appearance and disease, food system and intake of various main/side foods, concern about health and hygiene. North Korean's height and BMI were lower than those of South Koreans. Difference of BMIs between North and South Koreans was profound in middle aged women than in other age groups. Childrem showed many malnutrition appearances of moon face, large abdomem, arrow-like legs, flaky skin, decolored hair, etc.. Main foods in North Korea were rice-shaped corn, corn flour, wheat flour and wet noodle, and side foods were kimchi and/or soups and steamed soy paste. Food supply system there seemed not to work normally for many years, so foods, especially in cities, has been extremely short in government-operating shops, but some in private market. Many housewives were eager to make and sell simple snack food products, We noticed that North korea schools didn't check students' health even though their medical policy was based on preventive medicine. Their living environmental hygiene was shown to be oyt of control.

• Journal of Microbiology and Biotechnology
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• v.28 no.5
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• pp.748-756
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• 2018

Biofilms are of vital significance in bioconversion and biotechnological processes. In this work, sugarcane molasses was used to enhance biofilms for the improvement of the production of fumigaclavine C (FC), a conidiation-associated ergot alkaloid with strong anti-inflammatory activities. Biofilm formation was more greatly induced by the addition of molasses than the addition of other reported biofilm inducers. With the optimal molasses concentration (400 g/l), the biofilm biomass was 6-fold higher than that with sucrose, and FC and conidia production was increased by 5.8- and 3.1-fold, respectively. Moreover, the global secondary metabolism regulatory gene laeA, FC biosynthetic gene fgaOx3, and asexual central regulatory genes brlA and wetA were upregulated in molasses-based biofilms, suggesting the upregulation of both asexual development and FC biosynthesis. This study provides novel insight into the stimulatory effects of molasses on biofilm formation and supports the widespread application of molasses as an inexpensive raw material and effective inducer for biofilm production.

• Journal of the Korean Applied Science and Technology
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• v.24 no.2
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• pp.99-108
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• 2007

The cosmetic and toiletries are necessary health care & household for common life. However we need antiseptic which is effecting harmlessly to the human body. There are propolis, Lavender, Lemon, essential oil in the natural antiseptic materials. This work proceeded design Natural-antiseptic system with three materials as above-mentioned. Natural-antiseptic system was accomplished with propolis (2%), Lavender essential oil (0.3%), Lemon essential oil (0.3%) safety out of Polysorbate 20 (0.5%), Polysorbate 80 (0.5%), PEG (60) hydrogenated castor oil (0.45%), ethanol (5%). The antimicrobial test was experimented on E. coli and Bacillus stearothermophilus. In this antimicrobial test, we found that the effect of antisepsis against E. coli and Bacillus stearothermophilus with propolis 0.3%, Lavender essential oil 0.045% and Lemon essential oil 0.045% was improved. Therefore could expect Natural-antiseptic system product for moisturizing skin toner for face, nourishing essence and wet tissue for clean other things.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.9-19
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• 2020

Transferring of functional nanofilms onto target substrates is a cornerstone to developing nanofilm-based nextgeneration applications. In this work, we provide a brief review of recent advances on nanofilm transfer methods by categorizing them into the following three methods: wet-etching transfer, electrochemical delamination, and mechanical transfer. Furthermore, the mechanical transfer method, which is regarded as a promising technology owing to its facile, substrate recyclable, and widely applicable process, is overviewed by focusing on fracture mechanics approaches. Finally, the perspectives and challenges for future development of the mechanical transfer method are discussed.

• Korean Journal of Crystallography
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• v.14 no.2
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• pp.93-104
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• 2003

The crystals of group-Ⅲ nitride semiconductors with wurtzite structure exhibit a strong polarity. Especially, GaN has characteristics of different growth rate, anisotropic electrical and optical properties due to the polarity. In this work, GaN epilayer was grown and the polarities of the crystals were observed by the chemical wet etching and SP-EFM. GaN thin films were deposited on c-plane A1₂O₃ substrate under the variations of growth conditions by HVPE such as the deposition temperature of the buffer layer, the deposition time, the ratio of Group-V and Ⅲ and the deposition temperature of the film. The adquate results were obtained under the conditions of 500℃, 90 seconds, 1333 and 1080℃, respectively. It is observed that the GaN layer grown without the buffer layer has N-polarity and the GaN layer grown on the buffer layer has Ga-polarity. Fine crystal single particles were grown on c-plane A1₂O₃ and SiO₂, layer. The external shape of the crystal shows ｛10-11｝｛10-10｝(000-1) planes as expected in the PBC theory and anisotropic behavior along c-axis is obvious. As a result of etching on each plane, (000-1) and ｛10-11｝planes were etched strongly due to the N-polarity and ｛10-10｝ plane was not affected due to the non-polarity. In the case of the crystal grown on c-plane A1₂O₃, two types of crystals were grown. They were hexagonal pyramidal-shape with ｛10-11｝plane and hexagonal prism with basal plane. The latter might be grown by twin plane reentrant edge (TPRE) growth.

• Carbon letters
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• v.25
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• pp.33-42
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• 2018

Activated carbon (AC) was modified by ammonium persulphate or nitric acid, respectively. AC and the modified materials were used as catalyst supports. The oxygen groups were introduced in the supports during the modifications. All the supports were characterized by $N_2$-physisorption, Raman, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and thermogravimetric analysis. Methanol synthesis catalysts were prepared through wet impregnation of copper nitrate and zinc nitrate on the supports followed by thermal decomposition. These catalysts were measured by the means of $N_2$-physisorption, X-ray diffraction, XPS, temperature programmed reduction and TEM tests. The catalytic performances of the prepared catalysts were compared with a commercial catalyst (CZA) in this work. The results showed that the methanol production rate of AC-CZ ($23mmol-CH_3OH/(g-Cu{\cdot}h)$) was higher, on Cu loading basis, than that of CZA ($9mmol-CH_3OH/(g-Cu{\cdot}h)$). We also found that the modification methods produced strong metal-support interactions leading to poor catalytic performance. AC without any modification can prompt the catalytic performance of the resulted catalyst.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.830-833
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• 2003

This paper describes the fabrication and characteristics of 3C-SiCOI sotctures by SDB and etch-back technology for high-temperature MEMS applications. In this work, insulator layers were formed on a heteroepitaxial 3C-SiC film grown on a Si(001) wafer by thermal wet oxidation and PECVD process, successively. The pre-bonding of two polished PECVD oxide layers made the surface activation in HF and bonded under applied pressure. The wafer bonding characteristics were evaluated by the effect of HF concentration used in the surface treatment on the roughness of the oxide and pre-bonding strength. Hydrophilic character of the oxidized 3C-SiC film surface was investigated by ATR-FTIR. The strength of the bond was measured by tensile strengthmeter. The bonded interface was also analyzed by SEM. The properties of fabricated 3C-SiCOI structures using etch-back technology in TMAH solution were analyzed by XRD and SEM. These results indicate that the 3C-SiCOI structure will offers significant advantages in the high-temperature MEMS applications.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.157-160
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• 2005

The surface energies and acid-base interaction between the untreated and treated Jute or Hemp fibers and different matrix compositions of polypropylene-maleic anhydride polypropylene copolymers (PP-MAPP) were investigated using dynamic contact angle measurement. The contribution of the acid-base property into the interfacial adhesion of the natural fibers/matrix systems were characterized by calculating the work adhesion coming from the acid-base interaction. On the other hand, microfailure mechanism of both single Jute and Hemp fiber bundles were investigated using the combination of single fiber tensile test and acoustic emission. Distinctly different micro failure modes of the different natural fiber/polypropylene systems wet ε observed using optical microscope and determined indirectly by AE and their FFT analysis.