• Microbiology and Biotechnology Letters
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• v.42 no.1
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• pp.41-50
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• 2014

In this study, the performances of PVA-encapsulation and non-encapsulation in a fed-batch bioreactor system were compared for biohydrogen production. Hydrogen production in the PVA-encapsulation bioreactor was not significantly different in comparison to the non-encapsulation bioreactor. However, the hydrogen gas in the encapsulation bioreactor could be stably produced when it was exposed to environmental difficulties such as pH impact by the accumulation of organic acids as fermentative metabolic products. Bacterial communities by DGGE analysis were differently shifted between the PVA-encapsulation and non-encapsulation bioreactors from the initial sludge. The community of hydrogen producing bacteria was stable during the experimental period in the PVA-encapsulation bioreactor compared to the non-encapsulation method. The absolute quantitation of the DNA copy number by a high-throughput droplet digital PCR system for six genera contributed to hydrogen production showing that the numbers of dominant bacteria existed at similar levels in the two bioreactors regardless of encapsulation. In both of two bioreactors, not only Clostridium and Enterobacter, which are known as anaerobic hydrogen producing bacteria, but also Firmicutes, Ruminococcus and Escherichia existed with $1{\times}10^5-1{\times}10^6$ copy numbers of ml-samples exhibiting rapid growth during the initial operation period.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.991-994
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• 2017

In hypersonic aircraft, increase of aerodynamic and engine heat lead thermal load in airframe. It could lead structural change of aircraft's component and malfunctioning. Endothermic fuels are liquid hydrocarbon fuels which are able to absorb the heat load by undergoing endothermic reactions. In this study, we investigated the method of measuring the heat sink of catalyst by using exo-tetrahydrodicyclopentadiene as a fuel in a packed bed flow reactor similar to the actual reaction conditions.

• Microbiology and Biotechnology Letters
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• v.45 no.3
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• pp.257-264
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• 2017

Mixed substrate oil cakes are known to emit sulfides, ammonia, and amines. Microorganisms capable of removing odorous gases related to these sulfur compounds were isolated from colonies enriched in vials containing oil cakes and water. Activity tests for hydrogen sulfide and methyl mercaptan reduction were performed to measure the sulfide reduction ratio of the isolates. Control groups were prepared with 0.25 g oil cakes and 10 ml water in a 100-ml vial without inoculation. The experimental groups were prepared similarly, albeit with an inoculum. Hydrogen sulfide removal efficiency of >90% was observed for an isolate, which was identified as Brevundimonas diminuta by 16S rDNA sequence analysis. The sequence was deposited in the Korean Collection for Type Cultures under the accession number KCTC11724BP. B. diminuta could remove up to 200 ppmv standard hydrogen sulfide in 24 hours and demonstrated a maximum hydrogen sulfide and methyl mercaptan removal efficiency of 100% at 453 ppmv and 98 ppmv, respectively, in vial tests. Furthermore, B. diminuta cells in 20% (v/w) medium showed removal efficiency of >85% for sulfur compounds in an odor emission chamber for swine manure.

• Journal of the Korean GEO-environmental Society
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• v.10 no.2
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• pp.37-43
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• 2009

With the economic development of Korea, sewage treatment facilities and waste food treatment facilities have been steadily increased. These facilities have positive effects such as the conservation of the water resources quality and waste food recycling while they also affect the neighborhood life with severe odor problems. Therefore, it was first collected sludge samples from 5 sewage treatment facilities and 5 waste food treatment facilities where the amounts of waste produced from above sites are relatively immense in Busan and estimate the $H_2S$ emission rates. Then it was selected 1 sample which has the highest emission rate of $H_2S$. Using flux chamber and GC/FPD analyses, it was tried to quantify the emitted amount of sulfonic gas concentration under anoxic condition. The sludge sample obtained from Noksan sewage treatment facility has the highest emission rate of $H_2S$. This sample contained 156.18 mg/kg $H_2S$. The odor compounds were analyzed using GC/FPD and the concentrations were converted to odor quotient. Among odor compounds the ratio of $CH_3SH$ (methylmercaptan) for the total odor quotient was 47.3% and considered to be the main odor compound in the sample.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.325-329
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• 2017

In this study, the combustion experiment of hydrocarbon-kerosene fueled dual mode ramjet combustor was performed at mach number 3.5~6.0 conditions. Through the experiment, the temperature and the pressure distribution inside the combustion chamber were measured and the combustion characteristics inside the combustion chamber were investigated. In the mach number 3.5~5.0 range, it was able to identify subsonic combustion in the downstream combustion chamber. In the mach number 6.0 condition, the injected fuel from the injectors was naturally fired, and it was possible to confirm that supersonic combustion was successful in the upper chamber.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.385.2-385.2
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• 2014

그래핀은 전기적, 광학적, 역학적, 열적 특성 등이 아주 좋은 소재이다. Thermal Chemical Vapor Deposition (T-CVD) 장비를 이용 저 진공, 고온에서 CH4과 H2를 가스를 사용하여 그래핀을 합성을 하였다. 그래핀은 탄소만으로 이루어진 2차원 층상구조를 가지고 있다. 촉매 금속 위에서 합성이 이루어지기에 합성된 그래핀을 바로 다른 응용하기에는 어려움이 따른다. 따라서 촉매 금속에서 그래핀을 분리하여 원하는 곳으로 옮기는 과정이 필요한데, 이를 전사공정이라 한다. 최근 전기분해를 이용하여 발생되는 수소 버블을 사용하여 그래핀을 촉매로 사용되는 금속으로부터 분리해내는 Electrochemical Delamination(ED) 전사방식이 소개가 되었다. 이러한 전사 방식의 장점은 촉매기판을 제거하지 않음으로써, 다시 재활용이 가능하고, 공정에 필요한 시간이 짧다. 또한 표면에서 직접적으로 분리하는 방식이기에 촉매 금속의 양면을 사용이 가능하다. 이러한 ED방식의 장점이 있기에 공정의 최적 조건을 잡기 위하여 변수들을 바꾸어가면서 실험을 하였다. 전사된 그래핀은 표면을 광학현미경으로 확인하였고, 라만 분광기를 사용하여 라만 스펙트럼과 기본적인 전기특성을 확인하여 특성을 평가하면서, 기존의 전사방식을 사용한 그래핀 샘플과 비교분석 하였다.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.552-556
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• 2006

An advanced oxidation process catalyzed by iron ions in the presence of hydrogen peroxide, the so-called Fenton's reaction, has been applied to the treatment of steam generator chemical cleaning waste containing highly concentrated iron(III)- ethyl-enediaminetetraaceticacid (Fe(III)-EDTA) of 70000 mg/L. The experiments for the degradation of Fe(III)-EDTA were carried out not only with a simulated waste, but also with the real one. The effect of pH and the amount of hydrogen peroxide added to the waste on the degradation was examined, and the results were discussed in several aspects. The optimal pH to maximize the degradation efficiency was dependent on the amount of hydrogen peroxide added to the waste. i.e., when the amount of hydrogen peroxide was different, maximum degradation efficiency was obtained at different pH's. The optimal amount of hydrogen peroxide relative to that of Fe(III)-EDTA was found to be 24.7 mol ($H_{2}O_{2}$)/mol (Fe(III)-EDTA) at pH around 9.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05d
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• pp.113-118
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• 2003

투어멀린(Tourmaline)은 비대칭 쌍극자를 가진 천연 유극성 결정체로 광물 중에서 영구전기분극을 띄고 있는 유일한 물질로써 일명 "전기석"이라고 알려져 있다. 분극에 의한 자체 미약전류(약 $60{\mu}A$)와 함께 음이온 및 원적외선의 발생으로 최근 우리주변에서 건강과 환경을 위한 관심고조의 대상인 육방정계의 압전성 및 초전성을 띄는 붕규산염(주요성분: Mg, Fe, B, Si, Ca)으로, 투어멀린 원석이나 그 복합세라믹체의 면역지수가 ~1000에서 ~400,000 이상인 점을 비롯하여 그 유용성을 이용하려는 새로운 아이디어 신상품들이 계속 개발되고 있다. 뿐만 아니라 물분자를 만나면 수소$(H^+)$와 수산기 $(OH^-)$로 전기분해 하여 친수기와 소수기 부분으로 구분하며, $H^+$와 $OH^-$는 각각 $H_2O$와 결합하여 활성이 강한 hydronium ion$(H_3O^+)$을 생성하고, 물 속에서 계속 불안정한 상태로 존재하는 수산기는 계면활성 작용이 있는 hydroxyl ion$(H_3O_2^-)$을 형성하여 물을 약 알카리성 (pH~7.4)으로 바꿔주며, 물분자 클러스터 세분화와 미네랄을 용출, 공급하여 이 물이 체내에 흡수되면 살균, 항균성의 면역기능을 갖게 되며, 혈액정화 기능과 자율신경 자극으로 교감신경의 흥분을 억제해 준다. 이와 함께 전기분극을 띈 투어멀린 입자는 다른 물질에 비하여 경이적 수치의 원적외선을 발생하여 강력한 열 효과와 높은 침투력으로 인체의 혈액순환 촉진과 혈전용해 작용을 주어 건강과 활력에 도움을 주는 것으로 확인되어 많은 관심을 끌고 있다. 따라서 유익한 이용가치를 인정받고 있는 천연 투어멀린을 단독 형태나 또는 서로 상승효과를 줄 수 있는 유용한 타 물질과 혼합물을 구성하여 성형 또는 EPD 방법으로 전착한 후 소결 처리하여, 소결체의 특성 분석과 함께 물에 대한 전기 화학적 작용 및 항균 효과를 조사, 확인하여 수질개선 효과를 분석하고 그 응용성을 개발, 확보하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.778-781
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• 2003

투어멀린(Tourmaline)은 비대칭 쌍극자를 가진 유극성 결정체로 광물 중에서 영구적으로 전기분극의 특성을 띄고 있는 유일한 물질로써 일명 "전기석"이라고 알려져 있고, 자체의 미약전류(약 0,06mA)와 함께 음이온 및 원적외선의 발생으로 최근 들어 우리 주변에서 건강과 환경을 위한 관심고조의 대상인 육방정계의 압전성 및 초전성을 띄는 붕규산염(주요성분: Mg, Fe, B, Si, Ca)으로, 원석(면역지수 ~1000)에 비해 수백 배의 효력이 있는 투어말린 세라믹(면역지수 ~418,000)을 비롯하여 이것을 이용한 새로운 아이디어 신상품들이 계속 개발되고 있다. 뿐만 아니라, 물분자를 만나면 수소(H$^{+}$)와 수산기(OH$^{-}$)로 전기분해하여 친수기와 소수기 부분으로 구분하며, H$^{+}$와 OH$^{-}$는 각각 $H_2O$와 결합하여 활성이 강한 hydronium ion(H$_3$O$^{+}$ 과 계면활성 작용이 있는 hydroxyl ion(H$_3$O$_2$$^{-}$)을 생성하며, 물속에서 계속 불안정한 상태로 존재하는 수산기는 hydroxyl (-)ion을 형성하여 약 알카리성(pH~7.4)을 띄고 물의 클러스터 세분화와 미네랄을 공급해 줌으로 체내에 들어오면 살균, 항균능력이 있는 면역기능을 갖게 되며, 혈액을 정화하고 자율신경을 자극하여 교감신경의 흥분을 억제한. 이와 함께 전기분극을 띈 투어멀린 입자는 다른 물질에 비하여 경이적 수치의 원적외선을 발생하여 강력한 열 효과와 높은 침투력으로 인체의 혈액순환 촉진과 혈전용해 작용으로 건강과 활력에 도움을 주는 것으로 확인되어 많은 관심을 끌고 있다. 따라서 유익한 이용가치를 인정받고 있는 투어멀린을 유용한 타 물질과 혼합물을 구성하여 성형 또는 EPD 전착하여 소결한 뒤, 소결체의 특성을 분석하여 그 응용성을 개발, 확보하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.1
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• pp.1-11
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• 2022

In a gas turbine, fuel is exposed to a high temperature environment until it is fed to the combustor through the injector. Hydrocarbon fuels can coke under high temperature conditions, which can cause coking material to deposit on fuel lines or block the injector passages. In this study, a specimen simulating a fuel line located inside a gas turbine and Jet A-1 were heated using electric devices. Jet A-1 coking tests were performed by changing the wall temperature of the stainless steel specimen and the temperature of Jet A-1 supplied to the specimen. After the coked specimens were cut, the coking material and the inner surface were analyzed using an energy dispersive X-ray spectrometer and a field emission scanning electron microscope.