• Korean Journal of Medicinal Crop Science
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• v.19 no.2
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• pp.103-110
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• 2011

This study was performed to enhance anticancer activities of Lithospermum erythrorhizon by eluting high amount of shikonin through ultra high pressure process. Extraction yield was increased up to 5~10% by ultra high pressure process, compare to the normal extraction processes such as water solvent extraction, 70% ethyl alcohol solvent extraction. The cytotoxicity of the extracts ($1.0{\mu}g/m{\ell}$) from ultra high pressure process was showed the lowest cytotoxicity 13.4% for human lung cell (HEL299). The anticancer activities showed 80~85% by adding $1.0{\mu}g/m{\ell}$ of the extracts from ultra high pressure process in several cancer cell lines such as AGS, Hep3B, MCF-7 and HeLa cells. Among them, MCF-7 cell of the endocrine system was highest inhibited than other cells. The anticancer activities of the extracts from ultra high pressure extraction process showed 10~15%, which was higher than the extracts from normal extraction processes. From HPLC analysis of the extracts, the contents of shikonin in the extracts from ultra high pressure process was 11.42% (w/w), which was 20% higher than others. This results indicate that ultra high pressure process could increase the extraction yield of shikonin and other contents, which resulted in higher anticancer activities.

• Korean Journal of Materials Research
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• v.28 no.3
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• pp.166-173
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• 2018

Molybdenum (Mo) is one of the representative refractory metals for its high melting point, superior thermal conductivity, low density and low thermal expansion coefficient. However, due to its high melting point, it is necessary for Mo products to be fabricated at a high sintering temperature of over $1800-2000^{\circ}C$. Because this process is expensive and inefficient, studies to improve sintering property of Mo have been researched actively. In this study, we fabricated Mo nanopowders to lower the sintering temperature of Mo and tried to consolidate the Mo nanopowders through ultra high pressure compaction. We first fabricated Mo nanopowders by a mechano-chemical process to increase the specific surface area of the Mo powders. This process includes a high-energy ball milling step and a reduction step in a hydrogen atmosphere. We compacted the Mo nanopowders with ultra high pressure by magnetic pulsed compaction (MPC) before pressureless sintering. Through this process, we were able to improve the green density of the Mo compacts by more than 20 % and fabricate a high density Mo sintered body with more than a 95 % sintered density at relatively low temperature.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1614-1616
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• 2011

지중송전라인에서 전압등급의 상승은 선로손실을 줄이면서 밀집된 전력수요에 대응하거나 특별히 고전압 수요를 맞추기 위한 것으로 이것은 XLPE Cable의 제조기술이 향상되면서 지속적으로 진행되어온 초고압송전계통의 일반적 추세이다. 이러한 경향으로 해외에서는 케이블 도체의 송전용량을 증대시킬 수 있는 방법으로 케이블 도체에 에나멜 코팅을 하여 집합을 한다. 그러므로써 기존 케이블에서 발생되는 표피현상 및 근접효과에 의한 AC 저항 요소를 줄여 요구하는 전류용량을 기존 비소선절연 케이블에 비해 더 많이 송전할 수 있다. 하지만, 소선절연 케이블이 전류 용량을 증대 시킬 수 있는 장점은 있으나 접속재의 경우 도체의 에나멜 코팅을 제거해야 하는 문제점이 있다. 당사는 에나멜 코팅을 제거하는 방법을 개발 완료함으로써 본 접속재의 개발을 앞당길 수 있었다. 당사는 쿠웨이트 400kV MEW/C/3931 Project에 400kV XLPE 1C${\times}$2500SQ 소선절연 초고압송전라인을 적용하였는데 본고에서는 여기에 적용된 400kV XLPE 1C${\times}$25000SQ 소전절연 케이블 부속재의 신뢰성을 높이기 위한 설계방법, 시험 및 시공에 대하여 요약하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05e
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• pp.40-43
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• 2003

전기방전에 대한 shed 재료의 열화내성과 우수한 발수성의 장기간 유지특성은 폴리머 애자의 장기성능에 있어서 가장 중요한 인자들이다. 애자 제조시 무결점 성형성 또한 중요한데 열화내성을 확보하기 위해 다량의 ATH의 첨가가 수반되기 때문에 적절한 process oil의 사용이 불가피하다. 사용하는 오일의 종류와 량에 따라 옥외절연물의 장기성능에 영향을 주는 표면발수성이나 방전내성은 크게 차이가 나는 것으로 밝혀지고 있다. 본 논문에서는 화학적 구조와 정도가 다른 몇 가지 실리콘 fluid들을 실리콘 고무에 처방하여 기본물성과 초고압 옥외절연물의 shed 재료로서 장기성능에 영향을 주는 방전열화내성과 표면발수성의 회복특성을 평가하였다. 실리콘 고무의 무결점 사출성형에 가소도가 중요한데 동일한 무기물 첨가조건에서 유사한 가소도를 갖게 하는데 필요한 량은 fluid들의 종류에 따라서 상당한 차이가 있었다. 특히 PDMS는 점도는 낮지만 분자량이 커서 많은 량이 첨가되어 기계적 특성저하가 크게 일어났다. 코로나 처리후 발수성 회복특성은 fluid들의 분자크기와 반응기의 종류에 따라 상당히 영향을 받았으며 분자가 클수록 초기회복속도는 다소 느려도 최종의 상시발수성은 다소 높게 유지되었으며 2일 이내에 거의 초기 접촉각으로 회복되었다. 내아크성은 무게손실이 적을수록 오차범위도 작은 안정된 특성을 보였으며 fluid들의 종류에 따른 무게손실의 차이는 크지 않았다. 트래킹 방전에 의한 무게 감소는 fluid의 분자가 크면서 페닐기를 가진 fluid들이 첨가된 고무가 우수한 특성을 보였다.

• Ocean and Polar Research
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• v.32 no.2
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• pp.157-164
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• 2010

A marine alga, Spirulina maxima, was extracted under high pressure and low temperature conditions at 500 MPa and $60^{\circ}C$ for 5 and 10 min. A high pressure of 500 MPa was applied to improve process yields because of low temperature extraction. This method resulted in highest higher extraction yield of 26.1% (w/w) in comparison to those results obtained from conventional extraction methods which produced a yield of 17.6% (w/w) from water. The extracts from this process also showed 19% of low cytotoxicity against human normal fibroblast cells in adding 1.0 mg/ml of the highest concentration. The crude extract significantly reduced the production of Prostaglandin $E_2$ ($PGE_2$) from CCD-986sk cells and increased nitric oxide production by macrophages. These higher activities of enhancing skin immune functions were found to have high antioxidant extract properties, like a 98% increase in DPPH radical scavenging activity. The extracts from the high pressure process showed a higher elution of active components than other processes and generated new compounds based on HPLC analysis. This clearly indicates that the extracts from high pressure and low temperature conditions have higher skin immune activation properties that have not been previously reported.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.8
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• pp.675-685
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• 2016

A research area on liquid rocket engine has been suggested. Downsizing through combustion pressure rise and low price are major issues to gas generator cycle engines. A very high pressure turbopump and material against oxidizer rich environment may be necessary technologies for staged combustion cycle engines. Integrated analysis saving computing time is the trend of rocket engine systems analysis area. Other important research topics are the methane engine for reusable booster to reduce the cost, 3D printing and materials for high temperature or oxidizer rich environment.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.61-65
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• 2006

A thery was developed to design a high pressure vessel with combined structure of the metal and the composite to withstand the pressure of several tens of thousands psias to reduce the weight of the impulse motor which produces high level of thrust within several tens of seconds. The elastic-plastic stress analyses were carried out to prove the validity of the design theory A combustion chamber of the impulse motor was designed by the design theory, fabricated, and tested by the hydraulic pressure and the static firings. The bursting pressures from the tests were compared to those predicted by tile design theory and the stress analyses and found to be almost the same. It will be possible to design the high pressure vessel with combined structure of the metal and the composite very easily by the proposed design theory.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.5
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• pp.533-551
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• 2015

The rock fracturing during waterjet cutting is very complicated because rock is inhomogeneous and anisotropic, compared with artificial materials (e.g., metal or glass). Thus, it is very important to verify the effects of rock properties on waterjet rock cutting performance. Properties affecting the rock cutting efficiency have been variously described in the literature, depending on the experimental conditions (e.g., water pressure, abrasive feed rate, or standoff distance) and rock-types studied. In this study, a rock-property-related literature review was performed to determine the key properties important for waterjet rock cutting. Porosity, uniaxial compressive strength, and hardness of the rock were determined to be the key properties affecting waterjet rock cutting. The results of this analysis can provide the basic knowledge to determine the cutting efficiency of waterjet rock cutting technology for rock excavation-related construction.

• Korean Journal of Medicinal Crop Science
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• v.20 no.4
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• pp.270-276
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• 2012

This study was performed to enhance contents of low molecular weight ginsenoside Rh2 and Rg3 using an ultra high pressure and steaming process in wild cultured-Root in wild ginseng. For selective increase in contents of Rg3 and Rh2 in cultured wild ginseng roots, an ultra high extraction was applied at 500MPa for 20 min which was followed by steaming process at $90^{\circ}C$ for 12 hr. It was revealed that contents of ginsenosides, Rb1, Rb2, Rc and Rd, were decreased with the complex process described above, whereas contents of ginsenoside Rh2 and Rg3 were increased up to 4.918 mg/g and 6.115 mg/g, respectively. In addition, concentration of benzo[${\alpha}$]pyrene in extracts of the cultured wild ginseng roots treated by the complex process was 0.64 ppm but it was 0.78 ppm when it was treated with the steaming process. From the results, it was strongly suggested that low molecular weight ginsenosides, Rh2 and Rg3, are converted from Rb1, Rb2, Rc, and Rd which are easily broken down by an ultra high pressure and steaming process. This results indicate that an ultra high pressure and steaming process can selectively increase in contents of Rg3 and Rh2 in cultured wild ginseng roots and this process might enhance the utilization and values of cultured wild ginseng roots.

• Korean journal of food and cookery science
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• v.30 no.2
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• pp.183-192
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• 2014

This study was conducted to investigate the effect of superheated steam (SHS) on the improvement of quality during the manufacturing process of Samgyetang products. SHS cooking showed the increase in moisture content and the decrease in protein. In terms of chromaticity, the value of L was significantly higher in the $2^{nd}$ SHS cooking compared to conventional cooking. As for texture, the hardness decreased in Samgyetang with SHS cooking than conventional cooking. According to the results of the safety experiment with a 14-day refrigerations storage the total number of bacteria was lower in the SHS cooking compared to conventional cooking. The TBA value increased to 0.59-5.70 mg MD/kg after 15 days; VBN values were also 0.70-4.54 mg% in SHS cooking indicating a slight decomposition. Overall, it was found that SHS cooking and HHP were more preferred and also had an effect of reducing microorganisms, which were improvements in product quality and sanitation.