• Korean Journal of Medicinal Crop Science
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• v.17 no.5
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• pp.321-327
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• 2009

Sunlight, and in particular its UV component, is the major environmental trigger that underlies the major signs of human skin and skin cancer in general. Therefore, this study was carried out to investigate the UV protection effects of R. coreanus. R. coreanus was extracted by ultra high pressure extraction process at 500 MPa and $30^{\circ}C$ for 5 and 15 minutes. The cytotoxicity of the extracts extracted by ultra high pressure process on human dermal fibroblast cell CCD-986sk, human kidney normal cell HEK293, and human lung normal cell HEL299 was measured as 17.5%, 16.5% and 14.0%, respectively in adding $1.0\;mg/m{\ell}$ of the samples, which was much lower than that from conventional water extraction method at $100^{\circ}C$ as 23.2%, 22.5%, 21.2%. The secretion of $NO^-$ from macrophage showed $15.9\;{\mu}M$ on the R. coreanus extract from this process, which was higher than others. Prostaglandin $E_2$ ($PGE_2$) production from UV-induced human skin cells was also greatly decreased down to $510\;pg/m{\ell}$, compared to the control. From the results, we considered that the extracts from R. coreanus could be potent natural materials for skin anti-inflammation agent, and could be used as a potential anti-aging for the photo-damaged skin.

• Korean Journal of Medicinal Crop Science
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• v.19 no.2
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• pp.97-102
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• 2011

In this study, whitening activity of Lithospermum erythrorhizon extracts were investigated according to several extraction processes: water extraction at $100^{\circ}C$ (WE100) and $60^{\circ}C$ (WE60), 70% ethyl alcohol extraction (EE) and ultra high pressure extraction (HPE) at 500 MPa for 30 minutes at $60^{\circ}C$. The extracts from ultra high pressure extraction showed the highest tyrosinase inhibition and melanogenesis inhibition activities as 52% and 79.5%, respectively, in adding $1mg/m{\ell}$ than others extraction processes. HPE extracts also showed the strong reducing power as 3.19 that absorbance at 450 mm. The contents of polyphenol in WE100, we measured as $10.1{\mu}g/m{\ell}$ in adding $1mg/m{\ell}$. Extracts have a high total flavonoid contents by HPE as $4.1{\mu}g/m{\ell}$ at $1mg/m{\ell}$. We can conclude that better whitening activity of extracts from high pressure extraction was due to high antioxidant activities which could be extracted by higher polyphenol and flavonoid contents in HPE than others.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.6 s.58
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• pp.135-147
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• 2009

In order to develop the ultra high strength concrete over 400Mpa at 28 day, Low-heat portland cement, ferro-silicon, silica-fume and steel fiber were mixed and tested under the special autoclave curing conditions. Considering the influence of Ultra high strength concrete. normal concrete is used as a comparison with low water-cement ratio possible Low-heat portland cement. Additionally, as a substitution of aggregates, we analyzed the compressive strength of Ferro Silicon by making the states of mixed and curing conditions differently. In addition, SEM films testified the development of C-S-H hydrates of Type III & Type IV, and tobermolite, zonolite due to the high temperature, high pressure of autoclave curing. Fineness of aggregate, filler and reactive materials in concrete caused 420Mpa compressive strength at 28day successfully.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.912-915
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• 2004

A vacuum environment is very important for NGL(Next Generation Lithography) apparatuses such as EUVL(Extreme Ultra Violet Lithography) or EPL(Electron Projection Lithography) and so on. The performance of these systems is dominated by vacuum level of processing and positioning accuracy of a stage. So, ultra-precision stage usable in a high vacuum level is needed for the improved performance of these devices. In contrast to atmospheric condition, a special attention must be paid to guide bearing, actuator and other elements. In this paper, air bearing is adopted because of its very high motional accuracy. So, air bearing is designed to be vacuum compatible using differential exhaust method, which prevents air from entering into vacuum chamber. For this, leakage analysis is performed theoretically and verified from experiment.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.794-795
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• 2006

Metal powder for dust core application was developed. The powder can be produced improved high-pressure water atomization process. The process has produced powder of spherical shape and lower coercivity. The dust core obta ined shows lower core loss.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.9-15
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• 2001

The total pressure and partial pressure of small cavity for flat panel display have been successfully measured by using an ultra-high vacuum chamber with mass spectrometer. The total pressure in the panel was in the range of $10^{-6}$ Torr and the major partial pressure affecting increase in total pressure were those of Ar, $CH_4$and He. The baking temperature during evacuation process was very important for high-vacuum package, the total pressure and partial pressure of $CH_4$ were decreased as the increase of baking temperature.

• Polymer Science and Technology
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• v.8 no.2
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• pp.169-174
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• 1997

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.5
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• pp.20-28
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• 2014

The high velocity oxygen fuel spraying (HVOF) is a kind of surface modification process technology to form the sprayed coating layer after spraying the powder to molten or semi-molten state by the ultra-high speed at the high-temperature heat source and conflicting with a substrate. It is desirable to melt completely the thermal spray powder in order to produce the coating layer with an optimal adhesion, however, because a semi-molten powder in a spray process has the low efficiency and become a factor that degrades the mechanical property by the inducement of pore-forming within the coating layer. To improve the wear resistance, corrosion resistance and heat resistance, in this study, the plungers of high-speed and ultra-high pressure reciprocating hydraulic pumps for oil and water used in ironwork are produced with $420J_2$ and the coating layers of plungers are formed by the powders of WC-Co-Cr and WC-Cr-Ni including the high hardness WC. The surface of these plungers is modified by the super-mirror face grinding machine using variable air pressure developed in this laboratory, and then the characteristics of cross-sectional microstructure, and surface roughness and hardness values between no operation and 100 days-operation are examined and made a comparison. The fine tops and bottoms on surface roughness curve of oil-hydraulic pump plunger sprayed by WC-Cr-Ni are molded more and higher than those of water-hydraulic pump sprayed by WC-Co-Cr because the plunger diameter of oil-hydraulic pump is 0.4 times smaller than that of water-hydraulic pump and the pressure of oil-hydraulic pump exerted on the plunger is operated with the 70 bars higher than that of water-hydraulic pump. As a result, it is found that the values of centerline average surface roughness and maximum height for oil-hydraulic pump plunger are bigger than those of water-hydraulic pump plunger.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.166-169
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• 2001

22,000 Ton hydraulic press was developed using wire winding method. The hydraulic press consists of three piece of frame type. The outer layers of yoke-column frame and main cylinder linear were wound with piano wire(1mm${\times}$4mm) under controlled tension and the total length of wound wire was about 450Km. The developed hydraulic press is used for the forming of heat plate with ultra-large size. To obtain large force with relative small apparatus, high pressure of $1,500 Kgf/cm^2$ was supplied to main cylinder through pressure amplification by booster pump. Therefore sealing technique of main cylinder is so crucial that the seals were made of mitre ring type with super-elastic metal. The press total weight is about 150 tons, which is quite light and compact relative to that of conventional hydraulic press.

• The KSFM Journal of Fluid Machinery
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• v.20 no.2
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• pp.17-25
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• 2017

Prediction of performance and operating characteristics of a state-of-the-art ultra-supercritical (USC) steam turbine is an important issue in many ways. Theoretical and empirical correlation equations, developed a few decades ago, have been widely used in commercial programs for a prediction of performance. To improve of these correlation equations and apply them to the high pressure turbine of a USC steam turbine, computational fluid dynamic analysis was carried out and correlation equations to calculate efficiency variation of each stage were made. Both fluid dynamic characteristic and thermodynamic performance was analyzed for the development of the correlation equations. In particular, the impact of flow addition through an overload valve (OLV) between stages was examined throughly. The trend of pressure drop due to the flow mixing by the OLV flow addition was analyzed and an efficiency correlation equation considering the OLV flow was also made.