• 한국환경과학회지
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• 제15권3호
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• pp.193-201
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• 2006

Advanced oxidation processes involving $O_3/H_2O_2$ and $O_3/catalyst$ were used to compare the degradability and the effect of pH on the oxidation of 1,4-dioxane, Oxidation processes were carried out in a bubble column reactor under different pH. Initial hydrogen peroxide concentration was 3.52 mM in $O_3/H_2O_2$ process and 115 g/L (0.65 wt.%) of activated carbon impregnated with palladium was packed in $O_3/catalyst$ column. 1,4-dioxane concentration was reduced steadily with reaction time in $O_3/H_2O_2$ oxidation process, however, in case of $O_3/catalyst$ process, about $50{\sim}75%$ of 1,4-dioxane was degraded only in 5 minutes after reaction. Overall reaction efficiency of $O_3/catalyst$ was also higher than that of $O_3/H_2O_2$ process. TOC and $COD_{cr}$ were analyzed in order to examine the oxidation characteristics with $O_3/H_2O_2\;and\;O_3/catalyst$ process. The results of $COD_{cr}$ removal efficiency and ${\Delta}TOC/{\Delta}ThOC$ ratio in $O_3/catalyst$ process gave that this process could more proceed the oxidation reaction than $O_3/H_2O_2$ oxidation process. Therefore, it was considered that $O_3/catalyst$ advanced oxidation process could be used as a effective oxidation process for removing non-degradable toxic organic materials.

• 상하수도학회지
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• 제24권1호
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• pp.109-117
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• 2010

In the present study, the degradation characteristics of Lindane by Advanced Oxidation Processes(UV/$H_2O_2$, Photo-Fenton process) were studied. The degradation efficiency of Lindane in aqueous solution was investigated at various initial pH values, Fenton's reagent concentrations and initial concentrations of Lindane. GC-ECD was used to analyze lindane. Lindane has not been degraded without application of AOPs over two hours. But, approximately 5% of lindane was degraded with UV or $H_2O_2$ alone. Lindane with UV/$H_2O_2$ process showed approximately 7% higher removal efficiency than $H_2O_2$ process. In the UV/$H_2O_2$ process, the pH values did not affect the removal efficiency. The optimal mole ratio of $H_2O_2/Fe^{2+}$ for lindane degradation is about 1.0 in Photo-Fenton process. Also, the experimental results showed that lindane removal efficiency increased with the decrease of initial concentration of lindane. Under the same conditions, the order lindane of removal efficiency is as following : Photo-Fenton process > UV/$H_2O_2$ process > $H_2O_2$ process. In addition, intermediate products were identified by GC-MS techniques. Than PCCH(Pentachlorocyclohexene) was identified as a reaction intermediate of the Photo-Fenton process.

• 한국환경과학회지
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• 제12권9호
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• pp.997-1004
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• 2003

The objective of this research was to test whether, under controlled laboratory conditions, hybrid SNCR/SCR process improves N $O_{x}$ removal efficiency in comparison with the SNCR only. The hybrid process is a combination of a redesigned existing SNCR with a new downstream SCR. N $O_{x}$ reduction experiments using a hybrid SNCR/SCR process have been conducted in simple NO/N $H_3$/ $O_2$ gas mixtures. Total gas flow rate was kept constant 4 liter/min throughout the SNCR and SCR reactors, where initial N $O_{x}$ concentration was 500 ppm in the presence of 5% or 15% $O_2$. Commercial catalysts, $V_2$ $O_{5}$ -W $O_3$-S $O_4$/Ti $O_2$, were used for SCR N $O_{x}$ reduction. The residence time and space velocity were around 1.67 seconds and 2,400 $h^{-1}$ or 6000 $h^{-1}$ in SNCR and SCR reactors, respectively. N $O_{x}$ reduction of the hybrid system was always higher than could be achieved by SNCR alone at a given value of N $H_{3SLIP}$. Optimization of the hybrid system performance requires maximizing N $O_{x}$ removal in the SNCR process. An analysis based on the hybrid system performance in this lab-scale work indicates that a equipment with N $O_{xi}$ =500 ppm will achieve a total N $O_{x}$ removal of about 90 percent with N $H_{3SLIP}$ $\leq$ 5 ppm only if the SNCR N $O_{x}$ reduction is at least 60 percent. A hybrid SNCR/SCR process has shown about 26∼37% more N $O_{x}$ reduction than a SNCR unit process in which a lower temperature of 85$0^{\circ}C$ turned out to be more effective.be more effective.

• 한국세라믹학회지
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• 제44권3호
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• pp.137-141
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• 2007

$La_{2}O_{3}-TiO_{2}-SiO_{2}$ glass, a type that could not obtained so far by the conventional melting method, was prepared successfully using a sol gel process. Glass derived with the sol-gel process has compositions of $5La_{2}O_{3}-5TiO_{2}-90SiO_{2},\;5La_{2}O_{3}-10TiO_{2}-85SiO_{2}$, and $5La_{2}O_{3}-20TiO_{2}75SiO_{2}$. The UV-visible absorption edge of all glass compositions was below 400 nm. The measured density is in the range of 2.55-2.89, and was nearly identical to the calculated density and the refractive index of the glasses derived from the sol-gel ranges from 1.545 to 1.645. The molar additive coefficient of $TiO_{2}$ measured in this ternary system is lower than the calculated value, while the value of $La_{2}O_{3}$ is higher.

• 한국물환경학회지
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• 제21권6호
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• pp.664-668
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• 2005

An experimental study for the comparison of nitrogen and phosphorus removal efficiencies between $A^2/O$ and modified Phostrip (M-Phostrip process) were carried out with bench-scale reactors. In case of nitrogen removal efficiencies both of processes showed similar ones when influent organic loadings were high. However, M-phostrip process was more effective than $A^2/O$ at low organic loadings. This is why M-phostrip process consumes the whole mass of influent organics as a carbon sources for denitrification in anoxic reactor but the anoxic reactor of $A^2/O$ process utilizes the residual carbon followed by consumming a part of influent carbon for phosphorus release in anaerobic reactor. $A^2/O$ process required the influent COD/T-P and COD/TKN ratios were more than 56 and 10, respectively, to take place the phosphorus release in anaerobic process and phosphorus uptake in oxic process. However, the luxury uptake of phosphorus in M-phostrip process was not affected by influent COD/T-P and COD/TKN ratios and the adverse effect of nitrate in return sludge introduced to the p-stripper from the 2nd clarifier was not significant due to the configurational advantage of the p-stripper.

• 한국세라믹학회지
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• 제28권1호
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• pp.11-18
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• 1991

A precipitation method, one of the most effective liquid phase reaction methods, was adopted in order to prepare high-tech Al2O3/ZrO2 composite ceramics, and the effects of stress-induced phase transformation of ZrO2 on thermal shock behavior of Al2O3-ZrO2 ceramics were investigated. Al2(SO4)3.18H2O, ZrOCl2.8H2O and YCl3.6H2O were used as starting materials and NH4OH as a precipitation agent. Metal hydroxides were obtained by single precipitation(process A) and co-precipitation(process B) method at the condition of pH=7, and the composition of Al2O3-ZrO2 composites was fixed as Al2O3-15v/o ZrO2(+3m/o Y2O3). Critical temperature difference showing rapid strength degradation by thermal shock showed higher value in Al2O3/ZrO2 composites(process A : 20$0^{\circ}C$, process B : 215$^{\circ}C$) than in Al2O3(175$^{\circ}C$). The improvement of thermal shock property for Al2O3/ZrO2 composites was mainly due to the increase of strength at room temperature by adding ZrO2. The strength degradation was more severe for the sample with higher strength at room temperature. Crack initiation energies by thermal shock showed higher values in Al2O3/ZrO2 composites than in Al2O3 ceramics due to increase of fracture toughness by ZrO2.

• 유통과학연구
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• 제18권5호
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• pp.89-98
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• 2020

Purpose: The growth of online commerce is now becoming a major threat and a new opportunity for retailers. Existing offline retailers struggle to cope with new online retailers' threats by utilizing offline infrastructure. Besides, online retailers expand their online strengths to offline sales by opening their offline stores. Many retailers are paying close attention to the O2O business and the resulting changes. Thus, this research focuses on the O2O business model and process that retailers can adopt. Research design, data and methodology: Considering the features of products that retailers sell, this paper divides O2O business process with the following criteria: delivery lead-time and delivery area. And This research uses the business model canvas to define the features of O2O commerce business process. This paper also uses nine key elements in the business model canvas for analyzing the structure of O2O commerce business. Results: This paper suggests the delivery model of retailers respond to offline customer orders and summarizes the following results. (1) Considering characteristics such as logistics process, delivery area, and product type, we define the features of O2O business models: wide-area (warehouse) based O2O business model, regional area (store) based O2O business model and time-separated O2O business model. (2) This study checks the availability of the business model through the business cases of O2O business models. (3) This study also analyzes the O2O business model of domestic retail companies by the factors defined in the business model canvas. Conclusions: Retailers can adopt the O2O business process to fit their business requirements and strategy. The online retailers who deal with normal consumer products mainly have the wide-area based O2O business model. The wide-area based O2O business model can be suitable for retailers who manage inventory centrally. The time-separated O2O business model can be a good solution for fresh food retailers to operate the logistics process efficiently. And to shorten the delivery lead-time of fresh foods, the regional area based O2O business model can be fit to the retailer that utilizes its offline logistics or sales infrastructure. It may be much more important for retailers to share the inventory information with other branches and to change the role of offline stores.

• 한국분말재료학회지
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• 제29권1호
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• pp.41-46
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• 2022

In this study, we report the microstructure and characteristics of Ag-SnO₂-Bi₂O₃ contact materials using a controlled milling process with a subsequent compaction process. Using magnetic pulsed compaction (MPC), the milled Ag-SnO₂-Bi₂O₃ powders have been consolidated into bulk samples. The effects of the compaction conditions on the microstructure and characteristics have been investigated in detail. The nanoscale SnO₂ phase and microscale Bi2O3 phase are well-distributed homogeneously in the Ag matrix after the consolidation process. The successful consolidation of Ag-SnO₂-Bi₂O₃ contact materials was achieved by an MPC process with subsequent atmospheric sintering, after which the hardness and electrical conductivity of the Ag-SnO₂-Bi₂O₃ contact materials were found to be 62-75 HV and 52-63% IACS, respectively, which is related to the interfacial stability between the Ag matrix, the SnO₂ phase, and the Bi₂O₃ phase.

• 한국세라믹학회지
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• 제36권12호
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• pp.1327-1334
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• 1999

Behaviors of abnormal expansion during calcination process of Ba2Ti9O20 ceramics and its related effects on the sintering characteristics were investigated as a function of precursors. When BaCO3 and TiO2 powders were used as starting materials. BaTi4O9 phase which has relatively large molar volume was formed drastically with abnormal ex-pansion during the calcination at 95$0^{\circ}C$ to 115$0^{\circ}C$ ON the contrary using BaTiO3 and TiO2 powders as starting materials led to retardation of the formation of BaTi4O9 phase and concurrently suppressed the abnormal expansion during cal-cination process. Especially the calcined powder of BaTiO3 and TiO2 had advantages in the densification and formation of Ba2Ti9O20 single phase in the sintering process.

• 한국물환경학회지
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• 제29권1호
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• pp.74-80
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• 2013

본 연구에서는 오존과 오존/과산화수소 공정을 단독공정과 연속공정으로 각각 적용하여 피혁염색폐수의 색도 저감을 평가하였다. 오존 단독공정에서 색도 저감율은 65%였고, 오존 농도가 40 ~ 50 mg/L 이상으로 주입되면 오히려 색도가 증가하는 경향을 나타냈다. 반면에 오존/과산화수소 공정에서는 과산화수소 주입율을 오존 질량 대비 0.2와 0.3비율로 하였을 때, 색도의 증가 없이 완벽히 제거되었다. 비록 과산화수소의 주입이 색도 저감을 증가시키지만, 초기오존 소모량 구간에서는 과산화수소를 주입하여도 오존 단독 공정과 색도 저감율에서 큰 차이를 보이지 않았다. 결론적으로, 1단계에서 오존 단독공정으로 오존 소모량을 만족시켜주고 (30 ~ 40 mg/L), 그 이후에 과산화수소를 주입 하여 오존/과산화수소 연속 공정을 적용하는 것이 본 피혁 염색폐수의 색도 저감에 가장 효과적인 공정으로 평가되었다.