• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.3
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• pp.230-236
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• 2018

This paper deals with the improvement of pressurized quality for high maneuver aircraft. Anti-G Valve is a pressure regulating valve for inflating anti-G suits and providing a sense line signal for a g-compensated oxygen regulator. The new anti-g valve system is satisfied with military specification MIL-V-87255 and allowed the pilots to tolerate high-G exposures without any vibrations. The flight test was performed by two T/FA-50 pilots and other tests used the centrifuge made by anti-g developer. A comparison of the new anti-g valve with period one, it have better response and low chattering phenomenon.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.6
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• pp.548-556
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• 2015

The highly maneuverable fighter aircraft such as F-22, F-16 and F-15have the high maneuverability to maximize the combat performance, whereas the high maneuver characteristics might degrade the pilot's mission efficiency due to fatigue's increase by exposing him to the high gravity and, in the worst case, the pilot could face GLOC (Gravity-induced Loss Of Consciousness). The advanced aerospace company has applied the various technologies to improve the pilot's tolerance to the gravity acceleration, in order to prevent the pilot from entering the situation of the loss of consciousness. Especially, the Anti-G Suit(AGS) equipment to protect the pilot against the high gravity in flight could improve the mission success rate by decreasing the pilot's fatigue in the combat maneuver as well as prevent the pilot from facing GLOC. In this paper, a control algorithm is developed and verified to provide an optimal air pressure to AGS according to the gravity increase during the high performance maneuver. This result is expected, as the key technology, to contribute to the KF-X(Korean Fighter eXperimental), project in the near future.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.38 no.4
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• pp.277-287
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• 2012

To develop new therapeutic materials to prevent hair loss and enhance hair growth, we developed a medicinal herbal complex extract (MHCE) using 23 herbs traditionally used in oriental medicine. Medicinal Herbal complex extract was consist of Angelica gigas Nakai, Psoralea corylifolia Linne, Biota orientalis Endlicher, and Eclipta prostrata Linne, Rehmannia glutinosa Liboschitz var. purpurea Makino, Ligustrum lucidum Aiton, Polygonum multiflorum Thunberg, and Sesamum indicum Linne, Sophora angustifolia Sieboldet Zuccarini, Angelica dahurica Benthamet Hooker, and Leonurus sibiricus Linne, Salvia miltiorrhiza Bunge, Prunus persica Batsch, Commiphora molmol Engler, Chrysanthemum indicum Linne, Boswellia carterii Birdwood, Panax ginseng C. A. Meyer, Cnidium officinale Makino, Albizia julibrissin Durazzini, and Corydalis ternata Nakai that have traditionally been used for treating hair loss, preventing gray hair, anti-inflammation, and blood circulation in oriental medicine. In addition, we examined the hair growth effect of MHCE in vitro and in vivo. In vitro, we evaluated the effects of MHCE on cultured HFDPC, HaCaT cells, and murine embryonal fibroblasts (NIH3T3 cells). Also, we evaluated the ability of MHCE to prevent gray hair on murine melanoma cells (B16F1 cells). The hair growth-promoting effect of MHCE in vitro was also observed in vivo using C57BL/6 mice. Our results showed that MHCE significantly increased the proliferation of HFDPC (175 % proliferation at $50{\mu}g/mL$), HaCaT cells (133 % proliferation at $20{\mu}g/mL$), and NIH3T3 cells (120 % proliferation at $50{\mu}g/mL$). MHCE also showed consistent melanogenesis in B16F1 cells (154 % melanin synthesis at $50{\mu}g/mL$). Moreover, MHCE showed potential for hair growth stimulation in C57BL/6 mice experiments (98 % hair growth area on 4 weeks). These results indicate that MHCE may be a good candidate for promotion of hair growth.

• Geophysics and Geophysical Exploration
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• v.11 no.3
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• pp.204-213
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• 2008

This paper presents the analysis about the stability of the Pohang deep geothermal borehole drilled in 2006. Severe wellhole instability problems such as collapse and tight hole occurred in weak rocks while drilling. Optimal mud pressure (mud window) required to prevent instability problems during drilling is obtained from analysis on in-situ stress and rock strength. The window is bounded by vertical stress in its upper limit and by either collapse pressure or pore pressure in its lower limit. Mud window varies with different types of rocks. In the top-most semi-consolidated mudstone formation, no mud window can secure borehole stability. In some weak rock types (basic dyke and crystal tuff), the borehole pressure needs to be higher by $50{\sim}60%$ than hydrostatic pressure. That means a mud density of 1.5 g/$cm^3$ or higher should be applied during drilling in order to prevent excessive collapse around the borehole.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.4
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• pp.249-260
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• 1998

To understand the attachment of micro algae and their subsequent growths on artificial surfaces immersed in seawater, the relationship between attachment of diatoms on the immersed artificial substrates and species pool in the surrounding water was investigated. We used acryl slides for the study of diatom attachment and examined the surrounding water samples collected in Incheon Harbour from July 1995 to February 1997. Variations of species composition and abundances by exposure time in seawater were investigated during the early phase of biofilm formation on various substrates, e.g. glass, acryl, titanium, copper and antifouling paint-treated slides. Immigration rates of diatoms to acryl slides during spring and winter were significantly correlated with the abundance of benthic diatoms in surrounding water ($r^2$=0.78, p<0.01, n=42), suggesting that immigration rates were affected by variations of benthic diatom abundances in surrounding water. Immigration coefficient of monoraphid diatoms was 5 times higher than that of biraphid diatoms, but relative abundance of monoraphid diatoms was 3 times lower than that of biraphid diatoms on acryl slides in spring. In winter, immigration coefficient and relative abundance of centric diatoms were higher compared to other raphe forms. These results suggest that the attachment of diatoms seems to be caused by the abundance and immigration coefficients of benthic diatoms in surrounding water. Pennate diatoms predominantly attached to all artificial surfaces throughout all experimental periods. Interestingly, centric diatoms predominantly attached to all artificial surfaces in winter. Hantzschia virgata, Licmophora abbreviata and Melosira nummuloides appeared dominantly on antifouling paint-treated slides, probably being tolerant of the antifouling paint. During incubations, the abundance of attached diatoms increased exponentially on glass, titanium and acryl slides with exposure time. The maximum abundance was highest on glass slide, followed by acryl, titanium, copper and antifouling paint-treated slides. The growth rates of attached diatom community on all artificial surfaces were higher at temperature of $24-25^{\circ}C$ than that of $2-3^{\circ}C$. The growth rate of attached diatoms on glass slide was generally higher compared to other slides during the study period. Dominant morphotypes of observed species with exposure time in seawater were prostrate form Amphora coffeaeformis, fan shape Synedra tabulata, stalk type Licmophora paradoxa and chain type M. nummuloides. A micro-succession in the attached microalgal community was observed. The composition of dominant species seems to be the result of species-specific response to gradually limited space with development of microalgal film.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.2
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• pp.132-137
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• 1993

These studies were carried out to investigate the effects of ascorbate and $\alpha$-tocopherol administration on the biochemical parameters of liver function and hydroperoxidation in liver of chronically ethanol-treated rats. Forty healthy Sprague-Dawley (SD) rats weighing about 120g were used for this experiment and divided into the following 5 groups: control group (CON), ethanol control group (ECON), ascorbate treated group (EASC), $\alpha$-tocopherol treated group (ETOC) and ascorbate.$\alpha$-tocopherol mixture treated group(EASC + ETOC). Ethanol was administered orally by 5ml per kg, body weight per day for 8weeks. Antioxidants treated groups were administered orally by 5mg per kg body weight per day in saline solution for 3 weeks. Lipid hydroperoxides were analyzed by using chemiluminescense-high performance liquid chromatography (CL-HPLC) method phosphatidylcholine hydroperoxide value (PCOOH) in liver tissues. Ethanol treatment significantly (p<0.05) resulted in an increase in GPT and GOT activities and liver hydroperoxide values comparing with the untreated control, while administration of $\alpha$-tocopherol and ascorbate+$\alpha$-tocopherol to the chronically ethanol-treated rats significantly (p<0.001) decreased GPT and GOT activities and liver hydroperoxide value. These results indicate that dietary $\alpha$-tocopherol and $\alpha$-tocopherol combined with ascorbate administration may inhibit the formation of liver lipid hydroperoxidation in vivo and were very effective in recovering the liver function in chronically ethanol-treated rats.