• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.6
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• pp.105-112
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• 2013

Turbopump is typically an assembly of rotors and casings, and there are a number of joints between them. Every joint should be leak-proof, so there is always a seal to accomplish the goal. Among various seals, metal seals are advantageous in that they are robust at high pressure, and at wide range of temperature. In this study, flange joints using conical seal made of stainless steel, solid flat metal seal made of copper and metal C seal made of Inconel 718 were structurally designed and analyzed, considering both initial tightening and operating conditions.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.3
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• pp.93-102
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• 2023

This study investigated the possibility of treating heavy metal pollutants existing in the air in addition to simultaneously removing NOx and SOx by injecting oxidizing and reducing agents into a scrubber into a microbubble device to create an eco-friendly method that does not generate secondary pollutants. Lead compound (Pb) was selected as the heavy metal substance in the air to be treated with microbubbles, and the removal efficiency was confirmed. By treating microbubbles by connecting them to a scrubber, it was confirmed that not only NOx and SOx but also heavy metal substances in the air were reduced, cost was reduced, and secondary environmental pollutants were not generated. Through this study, it was possible to simultaneously remove NOx, SOx, and heavy metals at low cost by applying an eco-friendly method, rather than the existing high-cost treatment method such as SCR. If oxidizing agent, reducing agent, and microbubbles are used appropriately, economical and efficient air pollution can be achieved. Since material processing was possible, it is expected to be helpful in the technological development of environmental prevention facilities.

• The Journal of Internal Korean Medicine
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• v.35 no.1
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• pp.92-105
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• 2014

Objectives : Cisplatin is a widely used cancer therapy drug. However, nephrotoxicity resulting in increased oxidative stress is a major side effect of cisplatin chemotherapy, thereby limiting its chemotherapeutic use. Lycium chinense Miller (LCM) has been used as a traditional herbal medicine in various febrile and inflammatory diseases such as night sweat, cough, nosebleed, bronchitis, pulmonary tuberculosis, etc. In this study we investigated the protective and antioxidative potential of LCM against cisplatin-induced nephrotoxicity in rats. Methods : Twenty-four 8-week-old male Wistar rats were divided into four groups: normal untreated; cisplatin treatment only; LCM 10 mg/kg plus cisplatin treatment; and LCM 30 mg/kg plus cisplatin treatment. Twenty-four hours after the last cisplatin injection, all the rats were sacrificed, and serological changes were evaluated. The levels of NF-${\kappa}B$ activity and NOX-4, $p47^{phox}$, $p22^{phox}$, COX-2, iNOS, SOD, catalase expressions were analyzed in Western blot analysis. Results : Cisplatin injection caused an increase in the BUN level, which is a reliable indicator of renal toxicity. The levels of BUN, renal ROS, and renal TBARS were significantly reduced in the LCM groups compared with the cisplatin-only groups. The levels of $p47^{phox}$ and $p22^{phox}$, which are NADPH oxidase subunits, were increased in the cisplatin-only groups, whereas they were decreased in the LCM groups. The levels of renal NF-${\kappa}B$ activity and COX-2, iNOS expressions were increased significantly in the cisplatin-only groups compared with the normal groups, whereas they were decreased in the LCM groups. Compared with the cisplatin-only groups, renal GSH and GSH/GSSG increased in the LCM groups. Also, the administration of LCM increased levels of SOD and catalase as compared with the cisplatin-only groups. Conclusions : These results suggest that LCM protects cisplatin-induced nephrotoxicity via a mechanism that may involves the inhibition of oxidative stress by the activation of antioxidants.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.48.2-48.2
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• 2009

구리 나노분말은 우수한 전기전도도와 상대적으로 저렴한 가격으로 주목을 받고 있어이를 이용한 다양한 기술들이 개발 중에 있다. 이들 중 잉크젯 프린팅용 구리 나노잉크는 기존의 포토리소그래피방식의 복잡한 공정단계와 이로 인한 단가 인상을 해결할 수 있는 공정으로 기대되는 잉크젯 프린팅에 구리를 사용할 수 있게 해주어 광범위한 응용이가능할 것으로 기대되어 많은 연구가 진행되고 있는 분야이다. 실제로 구리 나노분말의 이용하게 될 때에있어서 어려운 점 중 하나가 바로 빠른 표면 산화의 문제이다. 이를 막기 위해 본 연구에서는 건식 분말코팅 방법을 이용해 octanethiol 자기조립박막을 구리 표면에 부착한 분말을 사용하여 구리 나노분말용액을 제조하는 실험을 수행하였다. 건식 분말 코팅에 의해 산화 방지막이 부착된 분말을 표면 활성제인 Diethanolamine을 이용해 안정적으로 분산시켜 잉크로 사용이 가능한 용액을 제조해 보고, 분산된 용액의 안정도를 확인하기 위해 zetapotential analyzer를이용하여 분산도를 분석하였다. 또한 분산된 용액의 활용 실험을 위해 유리 기판에 바른 용액을 질소 분위기의튜브로에서 $250^{\circ}C$, $300^{\circ}C$, $400^{\circ}C$의 온도에서 30분간 소결을 진행한 후 probe-station을 이용하여 전기 전도도를 측정하였다. 이렇게제작된 샘플은 Scanning Electronic Microscope 를 이용하여 소결된 상태의 표면의 사진을 찍어 서로 비교해보았다. $300^{\circ}C$에서 소결한 시편부터 소결이 시작되어 $400^{\circ}C$에서 소결한 시편은 다량의 소결목이 형성되었다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1996.11a
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• pp.193-198
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• 1996

고연소속도 HTPB/AP 추진제를 얻기 위하여 현재 각광받고 있는 3종의 철화합물 연소촉매를 선정하여 연소속도 증진효과와 기계적 특성, 공정성 및 노화특성에 미치는 영향을 검토하였다. 사용한 철 화합물은 HTPB 프리폴리머에 silicone-ferrocene이 그라프트된 $BUTACENE^$\circledR$$ 과 결합제 역할을 하는 acylaziridinyl ferrocene(AAF), 그리고 입자크기가 30nm인 $NANOCAT^$\circledR$$ superfine iron oxide(SFIO)이었다. 이들 철 화합물을 추진제에 적용한 결과 공정성의 경우 $BUTACENE^$\circledR$$ 은 혼합점도가 높았으나 pot life의 감소는 없었으며 AAF와 SFIO는 혼합점도는 비교적 낮은 반면 pot life가 현저히 감소하는 경향을 보였다. 추진제의 노화거동은 연소촉매를 사용하지 않았을 때보다 저하되었으나 metal deactivating 산화방지제인 $PRO-TECH^$\circledR$$ 과 함께 사용할 경우 공정성 및 노화특성 모두 바람직한 수준으로 향상되었다. 기계적 특성은 SFIO를 제외하고는 저하되었으며 $BUTACENE^$\circledR$$ 은 프리폴리머로서, AAF는 결합제로서의 기능이 다소 미흡하였다. 한편 연소촉매의 함량에 따른 촉매효과는 AAF>SFIO>$BUTACENE^$\circledR$$ 순이었고 철 함량 측면에서는 AAF>$BUTACENE^$\circledR$$ >SFIO 순이었다.

• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.93-96
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• 2008

500나노 입자 및 기본 물성이 우수한 이중층상구조금속수화물(LDH)를 합성하고 PVC 수지에 적용하여 고온, 저온열안정성 및 가공특성으로 인장강도, 신율, 체적저항 등이 우수한 시제품을 합성한 후 개발한 이중층상구조금속수화물(LDH) 시제품을 사용하여 무독성안정제(금속석검계), 내외부활제류, 가공조제, 산화방지제 등 기타 첨가제 등을 사용하여 PVC수지에 적용하여 수지배합에 따른 시험편을 제작하여 배합비별로 고온, 및 저온열안정성, 체적고유저항, 가공성(인장강도, 신율 등), 내후성, 초기 착색성 등 물성, 기계적 가공특성 및 성능이 우수한 할로겐수지용 무독성배합을 개발한다. 최종적으로 개발한 이중층상구조금속수화물(LDH)을 사용하여 제조하여 PVC 수지의 열안정성 및 기계적 가공특성이 우수한 중금속계대체용 무독성복합열안정제를 개발하였다.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.25 no.3
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• pp.95-99
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• 2019

In the modified atmosphere packaging of powdered infant formula, the oxygen inside the package may cause its quality deterioration and needs to be minimized for quality preservation. A way of oxygen scavenger inclusion in the single-serve package without contacting the product was devised for removing oxygen residing initially and permeating through the seal layer during the storage. A polyethylene/pulp multi-layer porous filter bag of 5 × 7 cm containing 13 g of powdered infant formula was packaged in an 8 × 9 cm size aluminium laminated film package with a Fe-based oxygen scavenger of 1.8 g. After nitrogen flushed packaging, the active packages were stored at 30℃ for 254 days with periodical quality measurement. The active package could remove the initial residual oxygen of 1.4% completely and maintain absence of oxygen for the whole storage, which contributed to reduced oxidation observed in lower product peroxide value compared to that of the product in the control package. There was no influence of packaging treatment on content of 5-hydroxymethylfurfural, reaction product of initial nonenzymatic browning. The devised oxygen-scavenging single-serve package showed a potential to improve the preservation of infant formula powder and extend the shelf life.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.864-870
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• 2017

The propellants are burned in the pre-burner of the staged combustion cycle engine, and the resulting hot gas drives the turbine, and the turbine operates the turbo pump. The burned gas passing through the turbo pump is supplied to the combustor at high temperature and high pressure, where the gas is supplied in an excess of fuel or an excess of oxidant depending on the amount of fuel or oxidant. When the cycle works at oxidizer-rich staged combustion, its metal pipe can ignite or explode by the impact of even small particles. In this study, we develop the powder combinations for anti-oxidation coating through the analysis of other coating materials and establish the coating process.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.125-131
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• 2018

Some propellants in a liquid rocket engine are burned in the pre-burner of a staged combustion cycle engine, resulting hot gas drives the turbine. The burned gas passing through the turbine is supplied to the combustor at high temperature and pressure. The form of the gas can be fuel rich or oxidizer rich dependent upon the mixture ratio or the engine scheme. When the cycle works at oxidizer-rich condition, the metal pipes composing the engine can be ignited or even exploded by an impact of very a small particle. In this study, we developed the powder combination and processes for an anti-oxidation coating through the analysis of various coating materials.

• Analytical Science and Technology
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• v.13 no.3
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• pp.282-290
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• 2000

In this study, polymer additives were extracted and separated by Soxhlet extraction method and the dissolution-precipitation method from a polycarbonate (optical grade) which completely absorbed UV light below 390 nm. Analytical techniques such as UV-Vis spectroscopy, FT-IR, and HPLC were applied to analyze additives in polycarbonate. Separated materials from the polycarbonate may be a complex mixture containing additives such as UV stabilizer, antioxidants (primary and secondary), monomers, and oligomers. Several compounds such as bisphenol A, Irganox 1010, and Cyasorb UV-5411 were identified by chromatograms and UV spectra obtained from RP HPLC analysis using Bondapak $C_{18}$ column, methanol mobile phase, and a photodiode array (PDA) detector. Also, the content of UV-5411 in the polycarbonate was about 0.12 wt% by a quantitative analysis through UV spectroscopy.