• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.6
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• pp.699-705
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• 2011

High-maneuver missile is a projectile which demands a strong momentum at short time. To produce a necessary thrust for the flight, the gas of high temperature and pressure is generated through explosive combustion of solid propellant, and a great thrust can be obtained by expanding this high temperature and pressure gas. Although the operating time of a rocket motor is less than a few seconds, a failure of part or ablation near the throat of nozzle may take place during the expansion of high temperature and pressure gas for great thrust. In other words, for the precise control of a missile an exact stress analysis considering both, the thermal stress caused by the heat transfer between combustion gas and wall, and the mechanical stress caused by the pressure change in the flow, should be considered first. In this connection, this study investigated the safety, as a point of view of stress and melting point of the material, of the pre-designed thrust generating structure which is subjected to high temperature and pressure as a function of motor operating time.

• Clean Technology
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• v.20 no.4
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• pp.359-366
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• 2014

Attrition characteristics of PKM1-SU particles, $CO_2$ absorbents for pre-combustion $CO_2$ capture process, and FCC particles, catalytic particles for hydro cracking of crude oil, were investigated at high temperature and high pressure conditions. Particle attrition tests were executed at various kinds of temperature ($0-400^{\circ}C$) and pressure (0-20 bar) conditions in a cylinder type bubbling fluidized bed with 15.1 cm diameter, 120 cm height and 1 mm orifice-sparger tube. Attrited particles before and after tests were analyzed by BET, optical microscopy, and particle size analyzer. Effects of bed material height (solid inventory) and steam injection were also verified by using ASTM D5757-95, conventional attrition test method.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.637-642
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• 2017

In this study, cold flow and combustion tests are conducted and analyzed to validate designed rocket engine head generating high temperature/pressure steam. At first, uni-injector was designed and manufactured, and cold flow test was conducted. Through this, differential pressure that can supply designed flow rate was confirmed. Also, Each injector's spray pattern were confirmed by patternator. Based on cold flow test results, we selected injectors among the candidates and arranged them on engine head, and cold flow and propellant spray tests were conducted. Finally, combustion test was carried out to analyze the flow rate, pressure, combustion efficiency. As a result, validation of rocket engine head for the development of the high temperature and high pressure steam generator has been completed.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.51-51
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• 2011

Acetate 섬유는 고감성 제품의 대표적 핵심소재로서 실크와 같은 우아한 광택과 청량감을 주어 고가의 의류제품으로 사용되지만 편직 및 염색가공 공정이 까다롭고 비교적 저분자량의 분산염료로 염색되어 내열성, 염색견뢰도 및 물에 대한 형태안정성이 떨어진다. 특히, Acetate 편직물은 이태리나 일본 등 섬유선진국에서도 제조가 까다로운 기술적 난이도가 매우 높은 제품군이다. 반면 Tri-Acetate는 Acetate의 장점을 가지면서 내열성, 내세탁성, 원상회복력(resilience)등이 우수하여 기존 Acetate 시장의 고급제품 용도로의 전개가 가능할 뿐만 아니라 PET 등의 물성 및 형태가 다른 복수의 소재성분을 직물 사이에 공존시킴으로써 새로운 태, 기능, 외관, 광택의 부여가 가능하며 이를 활용한 차별화된 고부가가치 시장의 창출이 기대된다. Acetate와 Tri-Acetate 모두 셀룰로오스의 친수기가 아세틸화된 구조를 가지는 소수성 섬유로 분자구조가 치밀하여 분산염료로 염색된다. 그러나 일반적으로 Acetate 섬유의 경우 Acetate용 일반분산염료를 사용하여 저온상압염색을 하는 반면, Tri-Acetate의 경우 고온고압 분산염료를 사용하여 고온고압염색을 한다. PET와 Tri-Acetate 복합소재의 경우, 두 소재의 염색거동이 비슷하여 고온고압 분산염료로 염색이 가능하지만 T/P 복합소재에 상응하는 염색을 위해서는 복합소재를 구성하는 각각의 섬유소재에 적합한 염료의 선정 및 염색법의 개발이 필요하다. 본 연구에서는 Tri-Acetate 및 T/P 복합소재에 대한 염색최적조건을 규명하고자 염색온도별, 2종의 분산염료의 농도별 염색성, 염색시료의 인열강도 및 견뢰도를 측정하여 적정조건을 도출하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.5
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• pp.817-822
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• 2006

Diamonds have been widely employed as polishing media for precise machining and noble substrates for microelectronics. The recent development of the split sphere press has led to the enhancement of low quality natural diamonds. Synthesized and treated diamonds are sometimes traded deceptively as high quality natural diamonds because it is hard to distinguish among these diamonds with conventional gemological characterization method. Therefore, we need to develop a new identification method that is cheap, fast, and non-destructive. We proposed using a new method of micro-Raman spectroscopy for checking the local HPHT residual stress to distinguish these diamonds from natural ones. We observe unique ~10f compressive and tensile strains at Type I and Type II diamonds after HPHT treatment. Our result implies that our proposed methods may be appropriate fur identification of the treated diamonds with appropriate reference samples.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.432-437
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• 2002

현재 비파괴 상태진단기술의 세계적인 연구동향은 비접촉식 시험기술, 실시간 광역기술, 고온 환경 하에서의 시험기술, 온라인 감시기술, 고감도, 고분해능, 소형화 및 무선통신기술 등을 개발하는 방향으로 연구가 활발히 진행되고 있다. 특히 고온 환경 하에서의 시험기술의 경우 철강공장 등에서 그 수요가 급증하고 있는데 반하여 국내의 경우 개발기술이 거의 전무하며 외국에서 전량 수입에 의존하고 있는 실정이다. 최근 여러 가지 다양한 복합재료와 공업용 재료들이 개발됨에 따라 이들 재료의 제작 공정이 복잡해질 뿐만 아니라 고온 및 고압의 공정조건이 요구되는 경우가 많다. 따라서 고온환경 하에서 재료의 특성을 비파괴적으로 검사할 수 있는 초음파 탐촉자가 요구된다고 하겠다. (중략)

• The Korean Journal of Food And Nutrition
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• v.29 no.3
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• pp.438-447
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• 2016

This study was conducted in order to investigate the physiochemical properties and antioxidative activity of red ginseng manufactured using the high temperature high pressure (HTHP) process, which is faster and simpler than the conventional process. According to increasing the steaming temperature, pressure and time, the content of minor non-polar ginsenosides, such as Rg3, Rk3, Rh4, Rk1 and Rg5 gradually increased. Also, the contents of acidic polysaccharide, total phenolic compounds and maltol gradually increased. Based on the results of the physiochemical properties and appearance quality, the optimum conditions of HTHP process were estimated as $140^{\circ}C$, $3kg/cm^2$ in 20 min. The total phenolic compounds and maltol contents of the HTHP process red ginseng (1.0% and 2.49 mg%, respectively) were higher than those of conventional red ginseng (0.23% and 0.60 mg%, respectively). In addition, the antioxidative activity was investigated using DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-aziono-bis(3-ethylbenzthiazoline-6-sulfonic acid)) radical scavenging activity. DPPH and ABTS radical scavenging activities of HTHP process red ginseng increased by 3.4 and 3.6 folds, respectively, compared with conventional red ginseng. In addition, total phenolic compounds and maltol contents, as well as the antioxidant activity of the HTHP process red ginseng were similar to black ginseng. The present results suggest that the HTHP process is available for the development of value-added red ginseng products.

• The Korean Journal of Food And Nutrition
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• v.25 no.4
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• pp.800-806
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• 2012

Reactive oxygen species (ROS) are produced by oxidative stresses which cause various chronic diseases such as diabetes and obesity. Ginseng (Panax ginseng C.A. Mayer) has been reported to contain various biological activities such as anti-cancer, anti-diabetic, neuroprotective, radioprotective, anti-amnestic and anti-aging effects. In this study, we investigated the effects of Panax ginseng, treated with high temperatures and high pressures, on oxidative stress in C2C12 myoblasts and 3T3-L1 adipocytes. Oxidative stress was induced in the C2C12 cells through the introduction of $H_2O_2$ (1 mM), and cells were then treated with various ginseng preparations: dried white ginseng (DG), steamed ginseng (SG) and high temperature and high pressure treated ginseng (HG). In addition, 3T3-L1 preadipocytes were treated with various ginsengs for up to 8 days following standard induction of differentiation. Our results show that HG treatment significantly protected oxidative stress in both cell lines and enhanced gene expression of antioxidant enzymes. Therefore, in this study, we investigated the protective effects of ginseng on the oxidative stress of adipocytes and muscle cells.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.2
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• pp.278-282
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• 2012

The objectives of this study was to compare the physicochemical properties and antioxidant activities of raw, microwave-treated, steam-treated and high temperature and pressure-treated garlic. The hardness and strength of microwave-treated and steam-treated garlic decreased compared to raw garlic. The hardness and softness increased but strength decreased in dried garlic-treated at $60^{\circ}C$ for 48 hr. The reducing sugar content of raw garlic was 0.041 g/100 g, and reducing sugar content of high temperature and pressure-treated garlic increased temperature. Total polyphenol content of microwave-treated and steam-treated decreased compared to raw garlic, while that of high temperature and pressure-treated increased with increasing temperature. $IC_{50}$ value of the electron donating ability of raw garlic was 3.07 mg/mL, and the highest $IC_{50}$ value was 2.16 mg/mL for microwave-treated garlic at the 4 min. The ABTS radical scavenging activity of raw garlic was 40.94 mg AEAC/mL, and the highest AEAC value was 76.51 mg AEAC/mL with high temperature and pressure-treated garlic at $150^{\circ}C$ at the 2 hr.

• 기계와재료
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• v.22 no.3
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• pp.96-109
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• 2010

자동차는 다양한 형상과 기능을 가진 부품소재의 집합체라 할 수 있다. 자동차의 고출력화에 의한 연비향상과 각국의 환경규제 강화 요건을 충족시키기 위해 자동차 엔진의 작동온도와 이에 따른 배기가스의 온도가 꾸준히 높아지는 추세이다. 따라서 고온재료의 선택과 사용이 보다 중요해 지고 있다. 자동차에 사용되는 고온 부품은 설계사양에 맞추어 그리고 경제적인 측면을 고려하여 내열재료를 사용하는 방법과 표면처리를 하는 두 가지 방법이 주로 채택되고 있다. 내열재료를 사용하는 대표적인 부품은 엔진을 구성하는 부품과 연소실로부터 나오는 고온 고압의 배기가스가 이동하는 배기계 부품이다. 엔진을 구성하는 부품 중에는 냉각수에 의해 온도가 제어되는 부분은 경제적인 소재가 사용되나 밸브와 같은 부품은 고온재료가 채용된다. 가장 높은 온도에서 사용되는 배기계 부품에는 경제성이 감안되면서도 높은 열적, 기계적 안정성이 동시에 요구되고 있다. 전통적으로 배기부품에는 구상흑연주철이 널리 사용되어 왔고 현재에도 원가 측면의 강점을 이용해 대부분의 차량에 적용되고 있으나 일부 고출력, 고배기량 엔진의 경우에는 주철의 한계온도 이상의 배기온도가 요구되어 스테인리스 강을 도입하고 있다. 또한 내열 타이타늄 합금, 금속간화합물과 같은 고온재료가 개발됨에 따라 고가의 차종에는 신재료가 이들 부품으로 채용되고 있다. 이 글에서는 배기계 부품의 설계적인 요소에 의한 열적, 기계적 측면의 내구 특성을 살펴보고, 이들 부품에 보편적으로 적용되는 고온 금속재료의 종류 및 기계적 특성을 소개하였다. 아울러 미래의 환경친화적 자동차용 고온 부품을 개발하기 위하여 연구되고 있는 Super Si+MO, 스테인리스 강, TiAl, 고온 타이타늄 합금 등과 같은 자동차 내열 부품으로 사용되는 신소재의 연구개발 동향에 관하여 기술하였다.