• KSBB Journal
• /
• 제19권1호
• /
• pp.33-37
• /
• 2004

최근 들어 succinic acid는 기존의 용도 이외에도 생분해성 고분자의 원료물질로서 주목받고 있다. 본 연구에서는 3차 amine인 TOA와 4차 amine 염인 Aliquat 336을 이용하여 succinic acid에 대한 반응추출을 실시하였다. 그 결과 Aliquat 336에 비해 TOA의 추출능이 더 높은 것으로 확인되었다. 또한 pH에 따른 추출능의 변화는 TOA, Aliquat 336 모두 pH 증가에 따라 추출능이 감소하는 것으로 나타났으며 Aliquat 336의 경우 pH의 영향은 TOA에 비해 적음을 알 수 있었다. succinic acid와 기하학적으로 다른 구조를 가지는 maleic acid의 경우 분자 내 수소 결합으로 인한 두 번째 카르복실기의 deprotonation이 어렵게 되므로 succinic acid에 비해 추출능이 좋은 것으로 나타났다.

• 대한화학회지
• /
• 제27권4호
• /
• pp.262-267
• /
• 1983

가압형 경수로의 일차 냉각수로부터 세슘 핵종을 선택적으로 분리하여 그 방사능을 결정하기 위한 Scheme이 연구되었다. 세슘의 분리는 dicyclohexyl-24-crown-8과 sodium tetraphenylborate에 의한 이온쌍 용매추출에 의해서 이루어졌으며 추출에 미치는 수소, 세슘, 나트륨 및 borate 이온의 영향이 연구되었다. 요오드와 크세논 핵종의 방해 현상은 각각 티오황산나트륨에 의한 요오드의 환원과 1N 염산수용액에 의한 역추출에 의해서 제거될 수 있었다

• 한국축산식품학회지
• /
• 제31권3호
• /
• pp.349-355
• /
• 2011

Russian deer velvet antlers were divided into three parts and subjected to a extraction process using hot water at 100, 110, and $120^{\circ}C$ or an extraction with 70% ethanol. Each extract was analyzed for its biochemical components, including uronic acid, sulfated-glycosaminoglycans (sulfated-GAGs), and sialic acid, and the antioxidant and anti-acetylcholinesterase activities were investigated. Different levels of uronic acid and sulfated-GAGs were observed in the extracts according to the water temperature used for the extraction, and contents decreased with increasing extraction temperature. The upper layer of each extract showed high amounts of uronic acid and sulfated-GAGs, followed by the middle and base layers. Ethanol extraction was more effective for recovering uronic acid than sulfated-GAGs. Sialic acid content was the highest in the $110^{\circ}C$ extracts but was not observed in the ethanol extracts. Velvet antler extracts showed strong antioxidant activities against DPPH and hydrogen peroxide as well as strong reducing power in a dose-dependent manner. However, the antioxidant activities were different in each layer and according to the extraction method. Additionally, velvet antler extracts exhibited inhibitory activity against acetylcholinesterase, which is associated with Alzheimer's disease, in a dose-dependent manner. These results suggest that velvet antler extracts are useful as a functional food ingredient and/or a pharmaceutical.

• 한국분말재료학회지
• /
• 제9권4호
• /
• pp.218-226
• /
• 2002

The purpose of the present study is to investigate the influence of thermal debinding and sintering conditions on the sintering behavior and mechanical properties of PIMed 316L stainless steel. The water atomized powders were mixed with multi-component wax-base binder system, injection molded into flat tensile specimens. Binder was removed by solvent immersion method followed by thermal debinding, which was carried out in air and hydrogen atmospheres. Sintering was done in hydrogen for 1 hour at temperatures ranging from 1000℃ to 1350℃ The weight loss, residual carbon and oxygen contents were monitored at each stage of debinding and sintering processes. Tensile properties of the sintered specimen varied depending on the densification and the characteristics of the grain boundaries, which includes the pore morphology and residual oxides at the boundaries. The sinter density, tensile strength (UTS), and elongation to fracture of the optimized specimen were 95%, 540 MPa, and 53%, respectively.

• 한국가시화정보학회지
• /
• 제21권2호
• /
• pp.102-110
• /
• 2023

With the global shift from a carbon-based economy to a hydrogen-based economy, understanding the sloshing phenomenon and its impact on boil-off rate (BOR) in liquid hydrogen (LH2) tank trailers is crucial. Here, we analyze the primary breakup process under sloshing phenomena in a liquid fuel tank. We observe the growth of multiple holes on the sheet-like structures and the formation of ligament structures reminiscent of jet atomization. Through the extraction of three-dimensional liquid regions, we analyze the geometrical characteristics of these regions, enabling the classification of sheets, ligaments, and droplets. The present findings could contribute to understanding the breakup mechanism and hold potential for the development of strategies aimed at minimizing BOR.

• 한국대기환경학회지
• /
• 제32권3호
• /
• pp.248-255
• /
• 2016

The leaves of three plant species, such as soybean, raspberry, and kudzu, exposed to hydrogen fluoride was collected in an area surrounding an emission source where the release accident occurred. The ultrasonic-assisted extraction and analysis of fluoride by ion chromatography was carried out. The mean concentration of fluoride in the leaves of three plant species exposed to hydrogen fluoride was $5,409{\pm}1,198mg\;F/kg\;dry\;wt$ and $788{\pm}339mg\;F/kg\;dry\;wt$, respectively. The mean fluoride concentration in ambient air were estimated to be $2.36{\pm}0.65mg/m^3$ ($2.89{\pm}0.79ppm$) and $0.35{\pm}0.15mg/m^3$ ($0.43{\pm}0.19ppm$) in exposed and unexposed sites, respectively. It seems likely that the passive monitoring using plant leaves could identify with respect to plant risk by fluoride in atmosphere.

• 한국토양환경학회지
• /
• 제4권3호
• /
• pp.67-75
• /
• 1999

비소는 자연적인 환경 하에서 음이온적인 거동을 하며 조건의 변화에 따라 다양한 형태로 전환되는 물질이기 때문에 적당한 처리방법이 없는 형편이다. 본 연구의 처리방법은 광미에 과산화수소를 첨가하여 비산철로 불용화 하는 방법으로 실제 구봉광산의 광미를 이용하여 실험한 결과 비소와 철의 용출농도가 각각 84%와 93%가량이 감소되는 것으로 나타났으며, 순수한 황철광과 비소표준용액을 이용하여 과산화수소를 첨가하는 실험에서는 과산화수소의 첨가량에 따라 비소의 농도가 직선적으로 감소하는 것으로 나타났다. 재용출 실험에서는 철은 약 80%, 비소는 약 90%가 용출이 억제되어 장기적 안정성면에서도 우수한 것으로 나타났다.

• KSBB Journal
• /
• 제25권5호
• /
• pp.421-428
• /
• 2010

본 논문은 복합흡수제를 이용하여 유해가스를 처리하기 위해 식물정유의 주요구성성분을 파악한 식물정유로 황화수소가스의 처리효율을 규명하고자 하였다. 또한 복합흡수제와 황화수소가스에 의한 제거반응을 위한 적정조건을 분석하였으며 그 결과는 아래와 같이 요약 할 수 있다. 1) 황화수소가스는 중화반응으로 처리하고 져 할 경우, 식물정유의 화학구조에서 알코올기, 알데히드기, 에스터기 등이 중화반응에 관여한다. 실험결과 앞서 언급한 화학작용기가 포함되어 있는 경우에 아민계열의 2-아미노에탄올 및 식물정유의 복합흡수제와 황화수소 가스와의 중화반응으로 염을 형성하여 유해가스 제거효율이 98%에 도달한다. 2) 황화수소가스를 제거하는 중화반응의 경우에 온도와 pH에 따라 처리효율이 크게 달라졌다. 높은 온도보다는 낮은 온도에서 제거효율이 거의 98%이상 나타났다. 적정 pH는 중성영역에서 비교적 처리효율을 확인하였다. 3) 황화수소가스의 처리효율은 초기농도에 따라 처리효율이 크게 차이가 나타났다. 황화수소의 초기농도가 1,100 ppm 이상인 경우에 처리효율은 40%로 나타났다. 반면, 240 ppm 이상인 경우에는 10분이내에 황화수소 가스 처리 효율이 90%이상 처리되는 것으로 나타났다.

• 한국분말재료학회지
• /
• 제20권1호
• /
• pp.43-47
• /
• 2013

The extraction of metallic pure vanadium powder from raw oxide has been tried by Mg-reduction. In first stage, $V_2O_5$ powders as initial raw material was reduced by hydrogen gas into $V_2O_3$ phase. $V_2O_3$ powder was reduced in next stage by magnesium gas at 1,073K for 24 hours. After reduction reaction, the MgO component mixed with reduced vanadium powder were dissolved and removed fully in 10% HCl solution for 5 hours at room temperature. The oxygen content and particle size of finally produced vanadium powders were 0.84 wt% and 1 ${\mu}m$, respectively

• Environmental Engineering Research
• /
• 제21권3호
• /
• pp.265-275
• /
• 2016

In this study, the microalga Neochloris oleoabundans was cultivated in a sustainable manner using diluted anaerobic digestate to produce biomass as a potential biofuel feedstock. Prior to microalgae cultivation, the anaerobic digestate was characterized and several pretreatment methods including hydrogen peroxide treatment, filtration, and supernatant extraction were investigated and their impact on the removal of suspended solids as well as other organic and inorganic matter was evaluated. It was found that the supernatant extraction was the most convenient pretreatment method and was used afterwards to prepare the nutrient media for microalgae cultivation. A bench-scale experiment was conducted using multiple dilutions of the supernatant and filtered anaerobic digestate in 16 mm round glass vials. The results indicated that the highest growth of the microalga N. oleoabundans was achieved with a total nitrogen concentration of 100 mg N/L in the 2.29% diluted supernatant in comparison to the filtered digestate and other dilutions.