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        검색결과 24

        1.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The 3-way valve have been used as a valve for opening and closing the valve by the flow control in the pressure system of the cryogenic and high pressure environment. In this paper, numerical analysis and experimental study on fracture nipple of 3-way ultra high pressure valve applied to space launch vehicle was carried out. We have developed a 3-way valve numerical simulation modeler of cryogenic environment using commercial software ANSYS 18.2. As results of numerical analysis, optimum nipple condition was derived. In addition, a 3-way valve prototype was fabricated and the fracture test was performed and compared with the numerical analysis results.
        4,000원
        5.
        2018.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        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 oC. 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.
        4,000원
        7.
        2006.09 구독 인증기관·개인회원 무료
        Refractory materials, such as W and Mo, are very useful elements for use in high-temperature applications. But it is not easy to fabricat pure W and Mo with very high density and retaining very fine grain size because of their high melting point. In this paper, a newly developed method named as resistance sintering under ultra high pressure was use to fabricate pure fine-grained W and Mo. The microstructure was analysis by SEM. The sintering mechanism is primary analyzed. Basic physical property of these sintered pure W and Mo, such as hardness, bend strength, are tested.
        8.
        2006.09 구독 인증기관·개인회원 무료
        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.
        9.
        2006.09 구독 인증기관·개인회원 무료
        The MIM industry is currently focusing on parts that are used in automobiles and medical instruments. Many of the parts in these categories are very small and often not easy to machine because of its complex geometry. Therefore MIM is well suited for the production of these parts. We tested the sinterability of SUS316L ultra fine powders (3,4, 6, 8micron) produced by ATMIX high-pressure water-atomization, and it showed excellent results. A density of 97% theoretical was obtained by sintering at 1373K when using the ultra fine powder (3micron). Specifically, the finer the powder size, higher was the sintered density. The surface roughness and accuracy are also greatly improved with ATMIX ultra fine powder.
        11.
        2018.04 서비스 종료(열람 제한)
        Effect of confining pressure on the shear strength of ultra-high-performance fiber-reinforced concrete (UHPFRCs) was investigated using a new shear test setup. Different confining pressures were applied and maintained to the specimens prior to shear testing. The shear strength of UHPFRCs was obviously sensitive to the confining pressure: the higher confining pressure produced higher shear strength. The confined shear strength could be expressed as a function of unconfined shear strength, confining pressure, and tensile strength.
        12.
        2015.10 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        본 연구는 산업 폐기물인 비지를 활용하여 부가 가치가 높은 가공식품을 개발하기 위한 일환으로 수행되었다. 즉 대두 가공 부산물인 비지를 활용하여 죽류, 음료류 및 유동 식 등의 제품으로 개발하기 위해, 초고압균질 가공 기술을 활용하여 초미세 비지 현탁액을 제조하고 추출수율, 영양 성분 및 항산화성을 확인하였다. 비지 분산액을 homogenizer 를 이용하여 1,0000 rpm에서 5분 분쇄한 후 1,000bar, 1,500bar 및 2,000bar의 압력을 가해 고압균질 가공 처리 하였다. 고압균질 가공처리한 모든 실험구가 대조군에 비 하여 추출수율이 유의적으로 증가하였다(p<0.05). 초고압 균질 처리 후 총당, 환원당 및 가용성 식이섬유의 함량은 유의적으로 증가하였으며, 불용성 식이섬유는 유의적으로 감소하였다(p<0.05). 단백질 함량과 유리아미노산 함량은 대조군보다 높은 경향을 나타내었다. 총 폴리페놀 함량은 처리 압력이 높아질수록 유의적으로 증가하였으며, ABTS 라디칼 소거능도 유의적으로 증대되었다(p<0.05). 초고압 균질 가공 기술은 비지의 영양성분과 항산화성을 증가시키 는 매우 효과적인 가공방법이며, 비지의 영양성분을 효율적 으로 활용하여 가공식품을 제조할 수 있음을 확인하였다.
        13.
        2014.10 KCI 등재 서비스 종료(열람 제한)
        Curcuma longa L. leaf was extracted by water at 60˚C for 12 hours after being treatment of Ultra High Pressure under 500 MPa for 5-15 minute. The high pressure extraction for 15 minute (HPE15) was measured the highest extraction yield of 25.48% (w/w), compared to those from conventional extraction methods. The HPE15 showed the lowest cytotoxicity as 11.97% in adding 1.0mg/mℓ of concentration. Also, HPE15 was measured the highest inhibition of hyaluronidase as 44.48% in adding 1.0mg/mℓ. In addition, The production of NO from macrophages was measured as 7.06μM in adding 1.0mg/mℓ of HPE15, which was lower than the those from others processes. Finally, HPE15 significantly reduced up to 649.44pg/mℓ of ProstaglandinE2 production from UV-irradiation. These results suggest that the Curcuma longa Linne leaf extract from high pressure process might enhance the skin immune activities possibly by high elution of active components than other processes.
        14.
        2014.04 KCI 등재 서비스 종료(열람 제한)
        This study was designed to evaluate antioxidant activity of Curcuma longa L. leaves treated by ultra highpressure extraction. Curcuma longa L. leaves was subjected to 5,000 bar for 5 and 15 min at 25℃ The highest phenolics andflavonoids content was observed in the treatment of high pressure extraction for 15 min (308.28㎍/㎎, 124.33㎍/㎎). TheDPPH scavenging activity was 82.34% at 1.0㎎/㎖ of Curcuma longa L. leaves treated by ultra high pressure process for 15min. The highest SOD-like acitivity of Curcuma longa L. leaves (1.0㎎/㎖) was observed at ultra high pressure extractionfor 15 min (67.54%). The high pressure extraction significantly increased the contents of phenolics and flavonoids and alsoenhanced the antioxidant activity. These results provide useful information for enhancing biological properties of Curcumalonga L. leaves.
        15.
        2013.10 KCI 등재 서비스 종료(열람 제한)
        본 논문에서는 초고압 특수 공간지를 활용한 다기능 포터블 카약을 제작하였다. 초고압 특수 공간지를 활용한 설계로 기존의 인플레터블 카약의 성능을 개선하여 하드쉘 카약의 성능에 근접하도록 제작하였다. 하드쉘 카약의 성능과 인플레터블 카약의 기능성 및 휴대성의 장점을 모두 가진 카약을 제작하였으며, 시제품 성능평가를 통해 기존 하드쉘 카약과의 성능을 비교하였다. 저항성능 검증결과는 목표속도 6knot에 대해 Hobie KONA kayak에 비해 Developed kayak이 12.33% 저항성능이 우수하였다. 경사시험결과는 동일배수량일 경우 Hobie KONA kayak 보다 Developed kayak의 무게중심이 선저를 기준으로 22.7% 낮게 분포하고 있으며, 이는 Hobie KONA kayak 보다 Developed kayak의 무게중심이 낮음으로 복원팔(GZ)에 대한 차이가 일정부분 감소된다. 선체 복원력에서는 Hobie KONA kayak이 약간 우수한 성능을 보여주었으나, 선회력과 저항계수면에서 Developed kayak이 더 우수한 결과를 보였다.
        16.
        2011.04 KCI 등재 서비스 종료(열람 제한)
        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 (1.0μg/ml) 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 1.0μg/ml 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.
        17.
        2011.04 KCI 등재 서비스 종료(열람 제한)
        In this study, whitening activity of Lithospermum erythrorhizon extracts were investigated according to several extraction processes: water extraction at 100℃ (WE100) and 60℃ (WE60), 70% ethyl alcohol extraction (EE) and ultra high pressure extraction (HPE) at 500 MPa for 30 minutes at 60℃. 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/ml 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 10.1μg/ml in adding 1mg/ml. Extracts have a high total flavonoid contents by HPE as 4.1μg/ml at 1mg/ml. 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.
        18.
        2010.06 KCI 등재 서비스 종료(열람 제한)
        We investigated a method to improve anticancer activities of Acer mono wood extracts by ultra high pressure extraction process. The A. mono was extracted by water at 40℃ and 300 MPa for 15 min (High Pressure Extraction, HPE). The extraction yield by ultra high pressure extraction process was 5.42%. The cytotoxicity on human normal lung cell (HEL299) of the extracts from HPE showed 21.54% lower than that from conventional water extraction at 100℃ in adding the maximum concentration of 1.0 mg/ml. Ultra high pressure extracts process for 15 minutes extracts (HPE15) showed more potent scavenging effect than the control, BHA. On SOD-like test, the HPE15 showed highest activity as 32.4% at 1.0 mg/ml concentration. Human stomach adenocarcinoma, liver adenocarcinoma, breast adenocarcinoma and lung adenocarcinoma cell growth were inhibited up to about 67~79%, in adding 1.0 mg/ml of extracts from HPE. HPE was 20~25% higher than conventional water extraction. It was interesting that, among several cancer cell lines (stomach adenocarcinoma, liver adenocarcinoma), the growth of digestive related cancer cells were most effectively inhibited as about 75~79%. On in vivo experiment using ICR mice, the variation of body weight of mice group treated A. mono wood extracts from HPE of 100 mg/kg/day concentration was very lower than control and other group. The survival times of group treated this extracts was 61.96% longer than that of the control group and this extracts showed the lower tumor weight, which were 10.49 g than positive control as 16.17 g. Based on these results, we could tell that the HPE wood extracts of A. mono had higher anticancer activity than conventional water extraction. The results of HPE showed obvious advantages in higher efficiency, shorter extraction time, at lower energy costs.
        19.
        2009.10 KCI 등재 서비스 종료(열람 제한)
        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℃ 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/ml of the samples, which was much lower than that from conventional water extraction method at 100℃ as 23.2%, 22.5%, 21.2%. The secretion of NO- from macrophage showed 15.9 μM on the R. coreanus extract from this process, which was higher than others. Prostaglandin E2 (PGE2) production from UV-induced human skin cells was also greatly decreased down to 510 pg/ml, 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.
        20.
        2009.04 KCI 등재 서비스 종료(열람 제한)
        This study was performed to enhance anticancer activities of E. sinica, and A. gigas by ultra high pressure extraction process. The cytotoxicity of E. sinica and A. gigas on human kidney cell (HEK293) was as low as 24.94% and 25.3% in adding 1.0 mg/ml of the sample extracted at 500 Mpa for 15 minute. Generally, the inhibition of cancer cell growth on A549 and MCF-7 was increased over 20% in the ultra high pressure samples, compared to the conventional extraction process. Under the extracts from ultra high pressure process showed not only the strongest anticancer activities, but also had better stability than normal extracts. It was also found that the extracts of A. gigas reduced the hypertrophy of the internal organs, such as adrenal and spleen caused stresses in several mouse models.
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