• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.12
• /
• pp.2247-2254
• /
• 2000

This study was carried out to investigate the reaction characteristics of NOx with reagents to grope the power consumption rate reduction and NOx removal rate improvement for the non-thermal plasma denitrification process. The experiments were performed using the real flue gas and wire-plate type plasma reactor. and the flow rate of real flue gas is $20Nm^3/hr$. Paraffinic and olefinic hydrocarbons and ammonia were used as reagents. Olefinic hydrocarbon oxidizes NO more actively than paraffinic hydrocarbon under the non-thermal plasma conditions, resulting in the generation of large amount of $NO_2$ and a very small amount of CO. When the initial NOx concentration increases. oxidation rate of NO decreases and the consumption rate of olefinic hydrocarbon increases significantly. On the other hand. $NH_3$ did not promote reduction reaction with NO under non-thermal plasma conditions. however, there was a tendency that the NHa was effective to remove the $NO_2$ oxidized by olefinic hydrocarbon.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.7
• /
• pp.729-734
• /
• 2008

The higher valence state of iron i.e., Fe(VI) was employed for the treatment of Cu(II)-EDTA in the aqueous/waste waters. The ferrate(VI) was prepared through wet oxidation of Fe(III) by sodium hypochlorite. The purity of prepared Fe(VI) was above 93%. The stability of Fe(VI) solution decreased as solution pH decreased through self decomposition. The reduction of Fe(VI) was obtained by using the UV-Visible measurements. The dissociation of Cu(II)-EDTA complex through oxidation of EDTA using Fe(VI) and subsequent treatment of organic matter and metal ions by Fe(III) reduced from Fe(VI) in bench-scale of continuous flow reactor were studied. The removal efficiencies of copper were 69% and 79% in pH control basin and reactor, respectively, at 120 minutes as retention time. In addition, Cu(II)-EDTA in the reactor was decomplexated more than 80% after 120 minutes as retention time. From this work, a continuous treatment process for the wastewater containing metal and EDTA by employing Fe(VI) as muluti-functional agent was developed.

• Resources Recycling
• /
• v.22 no.3
• /
• pp.57-64
• /
• 2013

Sulfurization reaction characteristics of $Eu_2O_3$, uranium oxides($UO_2$, $U_3O_8$), mixture of $Eu_2O_3$ and uranium oxides, Eu-doped uranium oxides($(U,Eu)O_2$, $(U,Eu)_3O_8$), and phase-separated products prepared by HOX (High temperature OXidation) of $(U,Eu)O_2$ were investigated in the temperature range from 400 to $800^{\circ}C$. Only $Eu_2O_3$ in the mixture of $Eu_2O_3$ and uranium oxides was converted into $Eu_3S_4$ by sulfurization reaction at $450^{\circ}C$ without reaction between them. Sulfurization reaction behavior of $(U,Eu)_3O_8$ and $(U,Eu)O_2$ up to $600^{\circ}C$ was similar to $U_3O_8$ and $UO_2$, respectively, while they were sulfurized into Eu-rich $(U,Eu)S_x$ and ${\alpha}-US_2$ at $800^{\circ}C$. In the sulfurization of RE-rich $(U,Eu)_4O_9$ and $U_3O_8$ prepared by high temperature oxidation, it was confirmed that RE-rich $(U,Eu)S_x$ and UOS phases were formed at $600^{\circ}C$. For Eu-rich $(U,Eu)O_2$ and $UO_2$ prepared by reduction of HOX products, it was identified that Eu-rich (U,Eu)OS was formed at $450^{\circ}C$ by sulfurization of Eu-rich $(U,Eu)O_2$, while $UO_2$ remained unreacted.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.6
• /
• pp.2306-2310
• /
• 2010

Corrosion is a complex series of oxidation/reduction reactions between at the water-metal surfaces and materials in which the water is stored or transported. With respect to the corrosion potential of drinking water, the primary concerns include the potential presence of toxic metals, such as lead and copper; deterioration and damage to the household plumbing, and aesthetic problems such as stained laundry, and bitter taste. This study was performed to evaluate the effects of corrosion inhibitors on corrosion rates, Fe and Cu release concentration in water distribution pipes. Decrease of corrosion rates were strongly related to phosphate corrosion inhibitors. Considering that typical corrosion processes consists of a series of electrochemical reaction at the metal surface in contact with water, corrosion rates were positively correlated with Fe release.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
• /
• 1993.12a
• /
• pp.19-20
• /
• 1993

농산물의 수확 후 취급이나 가공중에 일어나는 효소적갈변 현상은 외관의 변색에 의한 소비자의 기호성을 저하시킬 뿐만 아니라 상품의 가치를 하락시키며, 경제적인 손실을 초래함으로서 현재 식품에 종사하는 기술자나 가공업자에게 가장 관심이 있는 분야이다. 효소적갈변의 주역을 담당하고 있는 polyphenol oxidase(PPO)(EC1.14, 18.1)은 대부분의 식품에 존재하고 있으며 monophenol의 hydroxylation에 의한 o-diphenol화합물의 형성반응(cresolase)과 o-diphenol화합물의 o-quinone으로의 산화반응(catecholase)을 촉배한다. 그리고 여기서 일단 생성된 o-quinone은 다시 다른 o-quinone이나 그밖의 단백질, 아미노산, 환원당 등의 여러 성분들과 상호 반응하여 갈변식품의 특유의 색소인 melanine을 형성한다. 효소적갈변에 의한 품질의 저하는 식품가공산업에서 해결되어야 할 하나의 큰 과제이다. 현재까지 식품산업에서 가장 널리 쓰이고 있는 효소적갈변 저해제는 sylfite류 이다. 그들은 새우의melanosis(blackspot)를 억제하며, 감자, 버섯, 사과와 다른 과채류의 갈변을 방지할 뿐 아니라 쥬우스와 포도주의 off flavors를 일으키는 폴리페놀 플리머의 형성을 감소 시킨다. 그러나 최근 sulfite가 사람의 건강에 좋지않는 부작용을 일으키며, 특히 천식을(asthma)을 지니고 있는 사람이 sulfite가 함유된 식품을 먹었을 경우 사망을 초래할 수 있어 식품첨가물로서 그들의 사용이 미국 FDA에 의해 재평가되고 있다. 최근에 FDA는 셀러드바에서의 sulfite사용을 금지 시켰으며 점차 감자가공품에의 사용을 금지하는 방향으로 나아가고 있다. 따라서 현재 실질적이고 기능적인 sulfite의 대체 화합물의 개발이 절실히 필요한 실정이다. 이러한 배경으로 본 강연에서는 효소적갈변 저해제의 개발과 그들의 식품가공에의 적용 현환 및 화장품, 의약품으로의 응용에 대해 설명하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.12
• /
• pp.1596-1607
• /
• 2000

The optimal design of auto-catalyst needs a good compromise between the pressure drop and flow uniformity in the substrate. One of the effective methods to achieve this goal is to use the concept of radially variable cell density. But this method has not been examined its usefulness in terms of chemical behavior and conversion performance. In this work, two-dimensional performance prediction of catalyst coupled with turbulent reacting flow simulation has been used to evaluated the benefits of this method n the flow uniformity and conversion efficiency. The results showed that two cell combination of 93cpsc and 62 cpsc was the most effective for improved pressure drop and conversion efficiency due to balanced space velocity and efficient usage of geometric surface area of channels. It was also found that large temperature difference between the bricks in case that the edge of the frontal face of brick has too much lower cell density(less than 67% of cell density of the center of the brick). This study has also demonstrated that the present computational results show the better prediction accuracy in terms of CO, HC and NO conversion efficiencies compared to those of conventional 1-D adiabatic model by comparison with experimental results.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.487.1-487.1
• /
• 2014

현재 전 세계 태양광 시장의 주류를 이루는 단결정 실리콘 태양전지의 효율적 한계를 뛰어넘기 위하여 여러 가지 기술적 구조적 시도들이 이루어지고 있다. 그 중 기존의 피라미드 형태의 텍스쳐링 표면 대신 나노와이어 형상을 가지는 태양전지 개발이 주목을 받고 있다. 실리콘 웨이퍼 표면에 나노와이어가 수직 배열되어 있거나 텍스쳐링 표면에 나노와이어 형상이 있을 경우 SiNx가 증착된 피라미드 텍스쳐링 표면보다 반사도가 월등히 낮아져 light trapping을 기대할 수 있어 태양전지 개발에 응용하기 위한 나노와이어 형상 최적화에 본 연구의 목적이 있다. 실리콘 나노와이어 합성법에는 여러가지 방법들이 있으나 본 연구에서는 비교적 짧은 시간과 상온에서 공정이 이루어지는 무전해 식각법을 이용하여 실리콘 나노와이어를 합성하였다. 무전해 식각법은 은 이온과 실리콘 사이에서 일어나는 산화-환원 반응이 나노와이어 합성의 주요 기전이기 때문에 균일한 나노와이어를 형성하기 위하여 균일한 은 박막 형성과 적절한 반응시간이 요구된다. 본 연구에서는 반응시간을 조절하여 나노와이어의 길이 변화와 반사도의 변화를 FE-SEM과 UV-Vis-NIR spectroscopy를 통하여 관찰하였고 그 결과 나노와이어가 실리콘 웨이퍼 표면에 수직 배열되어 있는 형태와 텍스쳐링 표면에 나노와이어 형상이 있는 경우 SiNx가 증착된 피라미드 텍스쳐링 표면에 비해 월등히 향상된 반사율을 얻을 수 있었다.

• Applied Chemistry for Engineering
• /
• v.5 no.5
• /
• pp.819-824
• /
• 1994

A membrane-like $H_3PMo_{12}O_{40}$-polysulfone film was prepared by blending $H_3PMo_{12}O_{40}$ with polysulfone using dimethylformamide as a common solvent. SEM and EDX analysis showed that $H_3PMo_{12}O_{40}$ was uniformly and finely distributed in the film catalyst. The ESCA measurement also revealed that the oxidation state of Mo was not changed. The $H_3PMo_{12}O_{40}$-polysulfone catalyst showed lower activity for acid-catalyzed reaction and higher activity for oxidation reaction than $H_3PMo_{12}O_{40}$ in ethanol conversion reaction. The oxidation activity of the film catalyst was about 10 times higher than $H_3PMo_{12}O_{40}$. The decrease of acidic activity was due to DMF strongly adsorbed in acid sites of $H_3PMo_{12}O_{40}$, whereas the increase of oxidation activity was mainly due to uniform distribution of $H_3PMo_{12}O_{40}$. Adsorption results showed that the surface character of $H_3PMo_{12}O_{40}$ was drastically increased, while the bulk property of that was almost same after blending. It is suggested that the control of surface/bulk property as well as acid/redox property of heteropoly acid would be possible by blending it with a polymer.

• Korean Journal of Soil Science and Fertilizer
• /
• v.18 no.1
• /
• pp.105-110
• /
• 1985

A incubation study was conducted to find out the effects of rice straw and gypsum as soil ameriolite on urease, nitrate and nitrite reductase activities in newly reclaimed saline sandy soil. The results obtained were summarized as follows: 1. Very low urease activities were observed in saline soil if contrast to high productive paddy soil. Urease activities were lower at 5 days than that of 25 and 50 days after incubation. Remarkably high urease activities were obtained by the application of rice straw and gypsum. 2. Comparing with NPK treatment, application of rice straw and gypsum were enhanced the activities of nitrate and nitraite reductase. 3. Positive correlation (r=0.5501 p=0.05) was obtained between urease activities and ammonium nitrogen concentration in soil. 4. Cyclic oxidation and reduction of nitrate and nitrite in soil were obtained in terms of first order microbial kinetics reaction in case of application of rice straw and gypsum, respectively. 5. Positive correlation (r=0.6296 p=0.05) was obtained between the activitie of nitrite reductase and nitrate reductase in soil.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.10 no.3
• /
• pp.145-153
• /
• 2005

I reviewed an ecological and environmental significance of microbial carbon respiration coupled to dis-similatory reduction of fe(III) to Fe(II) which is one of the major processes controlling mineralization of organic matter and behavior of metals and nutrients in various anaerobic environments. Relative significance of Fe(III) reduction in the mineralization of organic matter in diverse marine environments appeared to be extremely variable, ranging from negligible up to $100\%$. Cenerally, Fe(III) reduction dominated anaerobic car-bon mineralization when concentrations of reactive Fe(III) were higher, indicating that availability of reactive Fe(III) was a major factor determining the relative significance of Fe(III) reduction in anaerobic carbon mineralization. In anaerobic coastal sediments where $O_2$ supply is limited, tidal flushing, bioturbation and vegetation were most likely responsible for regulating the availability of Fe(III) for Fe(III) reducing bacteria (FeRB). Capabilities of FeRB in mineralization of organic matter and conversion of metals implied that FeRB may function as a useful eco-technological tool for the bioremediation of anoxic coastal environments contaminated by toxic organic and metal pollutants.