• 한국자동차공학회논문집
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• 제19권3호
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• pp.52-56
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• 2011

Active regeneration in CDPF requires $O_2$ which regenerates soot at high temperature. However, small amount of NO can interrupt $O_2$ regeneration in CDPF. To verify this phenomena, soot oxidation experiments using a flow reactor with a $Pr/CeO_2$ catalyst are carried out to simulate Catalyzed Diesel Particulate Filter (CDPF) phenomena. Catalytic soot oxidation with and without small amount of NO is conducted under tight contact condition. As the heating rate rises, the temperature gap of maximum reaction rate is increased between with and without 50ppm NO. To accelerate the $NO_2$ de-coupling effect, CTO process is performed to eliminate interfacial contact for that time. As CTO process is extended, temperature which indicates peak reaction rate increases. From this result, it is found that small amount of NO can affect tight contact soot oxidation by removal of interfacial contact between soot and catalyst.

• 한국환경과학회지
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• 제5권1호
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• pp.51-59
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• 1996

The purpose of this study was to evaluate the partial oxidation of the biological treatment plant effluents using Fenton's reagent as a pretreatment step prior to a tertiary biological oxidation of these effluents. Fenton's reagent was evaluated as a pretreatment process for inhibitory or refractory organics. Based on the Fenton oxidation system, the petrochemical wastewater treatment plant effluent was shown to have significant improvement in toxicity after oxidation with hydrogen peroxide. For example, at ranee of 42 ∼ 184 mg/L COD of petrochemical plant effluents, the COD removal efficiencies were from 38.2% to 60.1% after reaction with hydrogen peroxide 200 mg/L and Fe2+ 100 mg/L and reaction time was 30 minutes. The total TOC reduction were about 15.8∼22.4% with same test condition and difference between the overall removal rate and BOD/COD ratio after Fenton's oxidation estabilished in the biodegradation and otherwise meets the discharge standard or reuse for cooling tower make-up water.

• 대한금속재료학회지
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• 제47권4호
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• pp.228-234
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• 2009

It is well known that the formation of $SiO_2$, $Al_2O_3$ and/or other oxides at the steel surface during the annealing process deteriorates the surface quality of galvanized steels. It is important to minimize oxide formation during the annealing process for the superior surface quality of galvanized steels. In order to minimize the oxide formation on the steel surface, antimony was chosen as an alloying element to the commercial steels. Then, the effect of alloying element on the oxidation behavior was investigated. A small amount of antimony was added to two types of steels, one with 0.1% C, 1.0% Si, 1.5% Mn, 0.08% P, and the other with 0.002% C, 0.001% Si, 0.104% Mn, 0.01% P. Then, the oxidation behavior was investigated from $650{\sim}900^{\circ}C$ in the air. The addition of antimony to the steels retarded the outward diffusion of elements during the oxidation, resulting in reduction of the oxidation rate.

• 한국환경과학회지
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• 제31권4호
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• pp.319-328
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• 2022

This study investigated the treatment of acetaminophen in municipal wastewater by conventional ozonation, ozone-based advanced oxidation, ozone/UV, and the electro-peroxone process. The ozone/UV process and electro-peroxone process of electric power consumption increased 1.25 and 2.04 times, respectively, compared to the ozone process. The pseudo-steady OH radical concentration was the greatest in the electro-peroxone process and lowest in the ozone process. The specific energy consumption for TOC decomposition of the ozone/UV process and electro-peroxone process were 22.8% and 15.5% of the ozone process, respectively. Results suggest that it is advantageous in terms of degradation performance and energy consumption to use a combination of processes in municipal wastewater treatment, rather than an ozone process alone. In combination with the ozone process, the electrolysis process was found to be more advantageous than the UV process.

• The Korean Journal of Physiology and Pharmacology
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• 제9권3호
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• pp.173-177
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• 2005

The purpose of this study was to discern the critical point in skeletal muscle fatty acid oxidation by changing plasma free fatty acids (FFA) level in rat. In the study, 3 key steps in lipid oxidation were examined after changing plasma FFA level by acipimox. The rates of both palmitate and palmitoylcarnitine oxidation were decreased by decrease of plasma FFA level, however, carnitine palmitoyl transferase (CPT) 1 activity was not changed, suggesting CPT1 activity may not be involved in the fatty acid oxidation at the early phase of plasma FFA change. In the fasted rats, ${\beta}-hydroxy$ acyl-CoA dehydrogenase (${\beta}$-HAD) activity was depressed to a similar extent as palmitate oxidation by a decrease of plasma FFA level. This suggested that ${\beta}-oxidation$ might be an important process to regulate fatty acid oxidation at the early period of plasma FFA change. Citrate synthase activity was not altered by the change of plasma FFA level. In conclusion, the critical step in fatty acids oxidation of skeletal muscles by the change of plasma FFA level by acipimox in fasting rats might be the ${\beta}-oxidation$ step rather than CPT1 and TCA cycle pathways.

• 대한환경공학회지
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• 제22권6호
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• pp.1083-1091
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• 2000

본 연구는 펜톤산화 공정에서 발생되는 펜톤슬러지를 응집제와 펜톤산화 공정에서의 촉매로 재이용할 수 있는지 여부를 검토하여 고농도의 난분해성 유기물질을 함유한 침출수를 효과적이고 경제적으로 처리할 수 있는 기술을 개발하는데 그 목적을 두었다. Batch-Scale 연구 결과 펜톤슬러지를 응집제와 펜톤산화 공정의 촉매제로 혼합사용하여 응집 공정과 펜톤산화 공정에 적용할 경우 약품만을 사용하는 경우보다 응집제의 사용량을 50%, 펜톤산화 공정의 촉매제 사용량을 50% 감소시킬 수 있었으며, 응집 공정과 펜톤산화 공정에서 발생되는 슬러지의 발생량도 감소시킬 수 있는 것으로 조사되었다. 실험실 규모의 연속식 처리 실험을 수행한 결과 펜톤슬러지를 응집제로 재이용함으로써 평균 8.5% 정도 유기물 제거효율이 증가하였으며, 슬러지의 발생량은 35% 감소하는 것으로 조사되었다. 또한 펜톤슬러지를 펜통촉매제로 재이용함으로써 유기물 제거면에서 평균 5.3% 정도 효율이 증가하였으며, 슬러지의 발생량은 14% 정도 감소하는 것으로 조사되었다. 이상의 결과로 펜톤산화 공정에서 발생하는 슬러지의 재이용은 약품 비용이나 슬러지 처리 비용을 절감시킬수 있을 것으로 결론지을 수 있다.

• 한국지반환경공학회 논문집
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• 제23권10호
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• pp.5-12
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• 2022

본 연구에서는 유기오염물질 유출수 처리를 위한 UV/H₂O₂ 산화 공정을 조사하였다. 유통량과 특성을 고려하여 벤젠, 톨루엔, 페놀, 메틸에틸케톤 4종의 대표 오염물질을 선정하였다. 선정된 물질은 전처리를 고려하여 자연휘발과 가압부상조를 모사한 폭기 실험으로 제거되었다. 이후 다양한 과산화수소 농도 조건에서 UV/H₂O₂ 산화 실험을 수행하였다. 벤젠, 톨루엔은 높은 휘발성으로 인해 산화 공정에 도달하기 전에 대부분 휘발되었다. 벤젠과 톨루엔의 휘발을 고려하여 5mg/L의 초기농도에서 산화 실험을 수행하였다. 벤젠과 톨루엔은 모든 과산화수소 농도 조건에서 20분 후 100%의 제거를 달성하였다. 페놀은 휘발 실험에서 거의 제거되지 않았으며, 50mg/L의 초기농도로 산화 실험을 수행한 결과 0.12v/v%의 과산화수소 투입 조건에서 30분 후 100%의 제거를 나타냈다. 메틸에틸케톤은 휘발성 실험 결과 2시간 후 58%가 제거되었다. 메틸에틸케톤 초기농도 50mg/L의 UV/H₂O₂ 산화 실험에서 0.08v/v%의 과산화수소 조건에서 99.7%의 메틸에틸케톤이 제거되었다. 선정된 4종의 물질에 대하여 UV/H₂O₂ 공정이 높은 분해 효율을 보이는 것을 확인하였으며, 물질 별 과산화수소 투입량을 파악하였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권1호
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• pp.45-53
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• 2021

The removal of 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution by coupled electro-oxidation and Fe(II) activated persulfate oxidation process was investigated. The electrochemical oxidation was performed using carbon sheet electrode and persulfate using Fe(II) ion as an activator. The oxidation efficiency was investigated by varying current density (2 - 10 mA/㎠), electrolyte (Na2SO4) concentration (10 - 100 mM), persulfate concentration (5 - 20 mM), and Fe(II) concentration (10 - 20 mM). The 2,4-D removal efficiency was in the order of Fe(II) activated persulfate-assisted electrochemical oxidation (Fe(II)/PS/ECO, 91%) > persulfate-electrochemical oxidation (PS/ECO, 51%) > electro-oxidation (EO, 36%). The persulfate can be activated by electron transfer in PS/ECO system, however, the addition of Fe(II) as an activator enhanced 2,4-D degradation in the Fe(II)/PS/ECO system. The 2,4-D removal efficiency was not affected by the initial pHs (3 - 9). The presence of anions (Cl- and HCO3-) inhibited the 2,4-D removal in Fe(II)/PS/ECO system due to scavenging of sulfate radical. Scavenger experiment using tert-butyl alcohol (TBA) and methanol (MeOH) confirmed that although both sulfate (SO4•-) and hydroxyl (•OH) radicals existed in Fe(II)/PS/ECO system, hydroxyl radical (SO4•-) was the predominant radical.

• 대한화학회지
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• 제10권2호
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• pp.76-90
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• 1966

Ammonium sulfate synthesized by the air oxidation methods without catalyst using the reaction vessel which was fitted with fritted glass at the bottom of it and introducing, through the bottom, ammonia and air with constant flow rates to sulfurous acid solution of constant concentrations at the given temperatures. The experiment showed that the oxidation process was accelerated in accord with the increase of the air flow rates when the ammonia flow rate was constantly kept at ca. 100ml/min. in high temperatures. When the pH of the solution reached 9.0, the oxidation was nearly completed. It is assumed that in the process of reaction, $[O_{2}{\to}HSO_{3}^-]^{\neq}$ would be produced as an activated complex and the reaction was thought to be first order. The experiment indicated that the 0.5M sulfurous solution could be oxidized up to 98.54% at the flow rates of ammonia and air, 100ml/min., and 4l/min., respectively at $50^{\circ}C$.

• 동력기계공학회지
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• 제18권5호
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• pp.74-79
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• 2014

This article aims at investigating the effect of applied load and sliding speed on wear behavior of thermally spraryed STS316 coating. STS316 coatings were fabricated by flame spray process according to optimal parameters on steel substrates. Dry sliding wear tests were performed on STS316 coating using four different applied load as 10, 15, 20 and 25 N and four different sliding speed as 15, 30, 45 and 60 rpm. Wear behavior on worn surface was investigated using scanning electron microscope(SEM) and energy disperive X-ray spectroscopy(EDS). The dominant wear mechanism of STS316 coating under low applied load and sliding speed was oxidation on worn surface. However, under high applied load and sliding speed the principal wear mechanism was abrasion on oxidation film and damage of oxidation film.