• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.264-264
• /
• 2012

As an environment-friendly alternative energy resource, ethanol may be used to obtain hydrogen, a clean energy source. Thus, studies on catalytic reactions involving ethanol have been studied to understand the underlying principles in the reaction mechanism using various oxide-supported catalysts. Among them, Au-based catalysts have shown a superior activity in producing hydrogen gas. In the present study, Au/$TiO_2$ catalysts were prepared by deposition-precipitation method to understand their catalytic activities toward ethanol and acetaldehyde with increasing gold loading, especially at the very low Au loading regime. A commercially available $TiO_2$ (Degussa P-25) was employed and the Au loading was varied to 0, 0.1, 0.5, and 1.0 wt% respectively. The catalysts showed characteristic x-ray diffraction (XRD) features at $2{\theta}=78.5^{\circ}$ that could be assigned to the presence of gold nanoparticles. Its reactivity measurements were performed under a constant flow of ethanol and acetaldehyde at a flow rate of ${\sim}0.6{\mu}mol/sec$ and the substrate temperature was slowly raised at a rate of 0.2 K/sec. We observed that the overall reactivity of the catalysts increased with increasing Au loading along with selectivity favoring dehydrogenation to product hydrogen gas. In addition, we disclosed various reaction channels involving competitive reaction paths such as dehydrogenation, dehydration, and condensation. In addition, subsequent reactions of acetaldehyde obtained from dehydrogenation of ethanol, were found to occur and produce butene, crotonaldehyde, furan, and benzene. Based on the results, we proposed overall reaction pathways of such reaction channels.

• Current Photovoltaic Research
• /
• 제3권3호
• /
• pp.80-84
• /
• 2015

We suggest new emitter formation method using solid-phase epitaxy (SPE); solid-phase epitaxy emitter (SEE). This method expect simplification and cost reduction of process compared with furnace process (POCl3 or BBr3). The solid-phase epitaxy emitter (SEE) deposited a-Si:H layer by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) on substrate (c-Si), then thin layer growth solid-phase epitaxy (SPE) using rapid thermal process (RTP). This is possible in various emitter profile formation through dopant gas ($PH_3$) control at deposited a-Si:H layer. We fabricated solar cell to apply solid-phase epitaxy emitter (SEE). Its performance have an effect on crystallinity of phase transition layer (a-Si to c-Si). We confirmed crystallinity of this with a-Si:H layer thickness and annealing temperature by using raman spectroscopy, spectroscopic ellipsometry and transmission electron microscope. The crystallinity is excellent as the thickness of a-Si layer is thin (~50 nm) and annealing temperature is high (<$900^{\circ}C$). We fabricated a 16.7% solid-phase epitaxy emitter (SEE) cell. We anticipate its performance improvement applying thin tunnel oxide (<2nm).

• 공업화학
• /
• 제23권1호
• /
• pp.119-123
• /
• 2012

본 연구는 Mn/$TiO_2$ 촉매를 이용한 저온 $NH_3$-SCR 반응에서 산소의 역할에 대한 영향을 기술하였다. 촉매의 격자산소는 저온 SCR 반응에 참여하며, 기상의 산소는 환원된 촉매를 재산화 시키는 역할을 한다. 이러한 산소의 redox 특성은 SCR 반응활성에 중요한 요소로 작용하며, 격자산소의 이용능력은 표면에 노출된 망간의 산화상태에 큰 영향을 받는다. $TiO_2$ 담체 표면에 존재하는 Mn이 $MnO_2$의 망간산화물 형태로 존재할 때가 $Mn_2O_3$의 형태로 존재할 때보다 우수한 redox 특성을 가지며, 이러한 망간의 산화상태는 $TiO_2$의 비표면적에 큰 영향을 받는다.

• 공업화학
• /
• 제27권6호
• /
• pp.555-564
• /
• 2016

대기 중 이산화탄소의 재활용 기술과 재생에너지에 의한 물 분해 기술의 접목이 최근 가능해지면서 메탄올은 많은 관심을 받고 있다. 경제성이 유리하도록 메탄올 경제를 실현하기 위해서는 고활성 메탄올 합성 촉매를 제조하여야 하며, 이를 위해서는 논리적인 접근법이 필요하다. 공침법을 통해 제조하는 Cu/ZnO 기반의 촉매는 침전, 숙성, 여과, 세척, 건조, 소성, 환원 등의 복잡한 단계로 제조되며, 100년의 역사를 가지고 있음에도 불구하고 최근에야 침전 화학과 촉매 나노구조에 대한 기초적인 이해가 이루어지고 있다. 이에 본 고에서는 단계별로 합성 변수가 침전, 소성, 환원상태 물질의 물성에 미치는 영향에 대한 최근 결과들을 리뷰하고, 화학적 기억 효과라고 부르는 이들 물성들과 최종 촉매의 활성 사이의 관련성을 논의하였다. 제조 변수별 설명은 메탄올 합성을 위한 Cu/ZnO 기반 고활성 촉매를 제조하는 방법에 초점이 맞추어져 있다. 논의된 합성 전략은 공침법을 기반으로 하는 타 금속 또는 금속 산화물 담지 촉매의 제조에 활용 가능할 것으로 판단된다.

• 한국자동차공학회논문집
• /
• 제24권4호
• /
• pp.447-453
• /
• 2016

The reduction technologies of exhaust gas from both the off-road engine and on-road vehicles are important. It is possible to apply various combustion technologies with engines after the application of a treatment technology to this field. In this study, main injection timing, pilot injection timing, and exhaust gas recirculation (EGR) rate were selected as the experimental parameters whose effects on the emission of exhaust gases and on the fuel consumption characteristics were to be determined. In the experiment, the emission of nitrogen oxide (NOx) and Smoke, and the Torque at the same fuel consumption level, were measured. The experimental data were analyzed using the Taguchi method with an L9 orthogonal array. Additionally, analysis of variation (ANOVA) was used to confirm the influence of each parameter. Consequently, the level of each parameter was selected based on the signal-to-noise ratio data (main injection timing, 3; pilot injection timing, 3; EGR rate, 2), and the results of the Taguchi prediction were verified experimentally (error: NOx, 10.3 %; Smoke, 6.6 %; brake-specific fuel consumption (BSFC), 0.6 %).

• 한국자동차공학회논문집
• /
• 제18권4호
• /
• pp.31-39
• /
• 2010

Although driving patterns strongly influence greenhouse gas and air pollutant emission rate from light duty vehicles, emission measurements have been mainly based on chassis dynamometer testing with one standard driving pattern. And there has been limited work on quantifying the independent effect of driving parameters on emission rate because of multidimensional nature of real-world driving pattern. The objective of this study is to obtain the quantitative effect of relative positive acceleration (RPA) on vehicle emission rate. RPA has been used to define the occurrence of acceleration demanding large amounts of power in certain driving distance and shown to be a significant affecting parameter for real-world emission rate. 40 driving patterns have been developed with fixed driving parameters to investigate independent effect of RPA. For the same values of average vehicle speed and power, the trend in carbon dioxide emission rate and fuel consumption with respect to RPA is very clear. Emission rate of nitrogen oxide and particulate matter also increase with respect to RPA, but the trend is less clear. Carbon dioxide emission from diesel vehicle appear to be more affected by high accelerations compared to that from gasoline vehicle because of high intake air restriction during acceleration caused by turbocharger and intercooler. The results have implications for the possible reduction of environmental effects through better traffic planning and management, driver education and car design.

• 환경생물
• /
• 제17권2호
• /
• pp.183-190
• /
• 1999

The bioleaching of heavy metals from fly ash was performed by Thiobacillus thiooxidans MET isolated from the enrichment culture of an anaerobically digested sludge. The effect of solid concentrations on the efficiency of metal leaching was studied in shaken flasks. In the range of solid concentrations 20 g.L­$^1$to 100 g.L­$^1$T. thiooxidans MET oxidized S$^{0}$ to sulfate without any lag period. The final pH of slurry solution was decreased to below pH 1, and the final oxide-redox potential (ORP) was increased to over 420 mV in the solid concentrations below 100 g.L­$^1$. However, the initial lag period of 4 to 8 days was required to obtain the pH reduction and ORP increase of the slurry solutions in the range of solid concentrations 150 g.L­$^1$to 300 g.L­$^1$. The sulfur oxidation rate of T. thiooxidans MET in 20~100 g.L­$^1$solid concentrations was 0.70~0.75 g-S.L­$^1$ㆍ d­$^1$, but its sulfur oxidation activity was remarkably inhibited with increasing solid concentration over 150 g.L­$^1$. Increasing fly ash solids concentration in the range of solids concentration 20 g.L­$^1$ to 200 g.L­$^1$decreased the removal efficiency of Zn, Cu, Mn, Cr and Pb. The solubilization of heavy metals from fly ash was strongly correlated with the pH value of slurry solution. When the pH of slurry solution was reduced to 3, the solubilization process of Zn, Cu and Mn started, and their solubilization efficiency of Zn, Cu and Mn was progressively increased below pH 2. However, the solubilization process of Cr and Pb started at pH 2.5 and 2.0, respectively.

• 에너지공학
• /
• 제26권3호
• /
• pp.30-50
• /
• 2017

현재, 석탄이나 석유, 천연가스 등의 화석연료를 대량으로 소비하는 화력발전소나 각종 연료시설로부터 배출되는 배기가스에는 고농도의 $CO_2$가 포함되어 있으며, 지구온난화의 주된 원인으로 되어 있다. 종래, 이 대책법으로서 다방면으로부터 연구개발이 수행되고 있으며, 배기가스 중의 $CO_2$를 분리 회수하여 처분하는 것도 매우 유망한 방법의 하나라고 생각되고 있다. 이산화탄소의 화학적 이용이 적은 이유의 하나는, 이산화탄소가 탄소화합물 중에서도 산화되어 가장 안정한 상태로 존재하기 때문이다. $CO_2$ 배출의 관점에서 앞으로 $CO_2$를 화학적으로 유용한 화합물로 변환시키는 $CO_2$ 고정화 기술이 더욱 중요하다고 생각된다.

• Korean Journal of Acupuncture
• /
• 제28권2호
• /
• pp.23-36
• /
• 2011

목적 : 이 연구는 관절 및 심혈관계 질환 치료에 사용되는 송절(松節)(Pinus densiflora Gnarl)을 약침용 시료로 조제하여 본 약물의 항산화 효능을 규명하고자 하였으며 이를 다양한 시스템에서 검토하였다. 방법 : $FeCl_2$-ascorbic acid system에서 흰쥐 간조직의 지질과산화 반응을 관찰하였고, Fenton reaction system에서 자유기에 의한 plasmid DNA 분절을 유도하였다. 또한 deoxyribose assay를 통해 hydroxyl radical 소거능을 관찰하였고, NBT reduction assay로 superoxide radical 소거능을 검토하였다. 또한 human low-density lipoprotein(LDL)의 산화를 유도하기 위해 $CuSO_4$와 AAPH를 사용하였으며 relative electrophoretic mobility (REM) assay로 LDL 산화 억제 효능을 대조 항산화물질과 비교 검토하였다. 결과 : 송절 약침액은 자유기에 의한 간조직의 지질과산화(p < 0.01)및 DNA 분절을 현저하게 억제하였으며, hydroxyl radical, superoxide radical (p < 0.01), nitric oxide 및 peroxynitrite를 강하게 소거하였다. 또한 $CuSO_4$ ($IC_{50}=9.2{\pm}0.2\;{\mu}g/ml$)와 AAPH ($IC_{50}=34.8{\pm}5.1\;{\mu}g/ml$)에 의해 유도된 human LDL의 산화를 억제하였고, REM assay에서도 산화 억제 효능을 재확인할 수 있었다. 결론 : 송절 약침액은 활성산소종 및 활성질소종를 소거하였고, 지질과산화를 억제하였으며, 특히 human LDL의 산화적 손상을 방어하였다. 이에 본 약물은 자유기에 의한 심혈관의 산화적 손상을 효과적으로 보호할 것으로 판단된다.

• Korean Chemical Engineering Research
• /
• 제58권1호
• /
• pp.163-169
• /
• 2020

Synthesis of Fe-Co/meso-HZSM5 catalyst, intended to be applied in Fischer-Tropsch (FT) reaction was investigated. The study emphasized the effect of desilication agents, NaOH and KOH, on the catalyst materials properties. Impregnation composition of active metal (Fe and Co) was also examined. HZSM-5, converted from ammonium ZSM-5 through calcination, was treated with NaOH and KOH for desilication, followed by impregnation with 10% metal loading. Fe composition in the initial mixture was varied at 10-50% from total composition. After impregnation, reduction was applied by flowing hydrogen gas at 400 ℃ for 10 hours. The use of KOH solution induced greater mesoporous volumes; however, it had a detrimental effect on zeolite crystal structure. NaOH solutions, on the other hand, increased mesopore area as high as 100%, indicated from surface area increase from 266.28 m²/g of HZSM-5, to 526.03 m²/g of NaOH-desilicated HZSM-5. In addition, the application of NaOH solution increased pore volume from 0.14 cc/g to 0.486 cc/g. Further, more Fe-Co alloys and less oxide of iron (Fe₂O₃) as well cobalt (Co₃O₄) had been commonly observed in the produced catalysts. The largest Fe-Co alloys could be found in 50Fe-50Co/HZSM-5