검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 429

        381.
        2011.02 KCI 등재 서비스 종료(열람 제한)
        Diethyl phthalate (DEP) and nonylphenol (NP) are widely spread in the natural environment as an endocrine disruption chemicals (EDs). Therefore, in this study, ultrasound (US) and ultraviolet (UVC), including TiO2, as advanced oxidation processes (AOPs) were applied to a DEP and NP contaminated solution. When only the application of US, the optimum frequency for significant DEP degradation and a high rate of hydrogen peroxide (H2O2) formation was 283 kHz. We know that the main mechanism of DEP degradation is radical reaction and, NP can be affected by both of radical reaction and pyrolysis through only US (sonolysis) process and combined US+UVC (sonophotolysis) process. At combined AOPs (sonophotolysis/sonophotocatalysis) such as US+UVC and US+UVC+TiO2, significant degradation of DEP and NP were observed. Enhancement effect of sonophotolysis and sonophotocatalysis system of DEP and NP were 1.68/1.38 and 0.99/1.17, respectively. From these results, combined sonophotocatalytic process could be more efficient system to obtain a significant DEP and NP degradation.
        382.
        2011.02 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        본 연구에서는 도라지 분말을 유기용매로 추출한 후 도라지의 추출물과 분획물들에 의한 세포 내 활성산소종 및 glutathione (GSH)를 측정하여 항산화효과를 검토하였고 NO 생성 저해 효과를 알아보았다. 세포 내 활성산소종 생성억제 실험에서 건조 도라지의 A+M 및 MeOH 추출물과 추출물을 n-hexane, 85% aq. MeOH, n-BuOH, water로 다시 추출하여 얻어진 각각의 분획물들을 농도별로 HT1080 세포에 처리하였을 때
        383.
        2011.02 KCI 등재 서비스 종료(열람 제한)
        씀바귀추출물이 비만을 유도한 흰쥐의 지질강하 및 항산화 효과에 미치는 영향을 검토하였다. 혈장 유리지방산과 triglyceride농도는 대조군과 비교하여 씀바귀추출물 투여군은 농도 의존적으로 낮은 값을 나타내었다. 혈장 내 total cholesterol 농도와 LDL-cholesterol 농도는 씀바귀추출물 투여군 모두에서 감소하는 경향을 보였다. 그러나, HDL-cholesterol농도는 처리군 들 간에 유의한 차이를 나타내지 않았다. 간장 total cholesterol과 triglyceride량은 씀바귀추출물 투여군 들이 대조군보다 낮은 값을 나타내었다. 혈장 및 간장의 TBARS 농도는 씀바귀추출물 투여군 들 모두가 대조군보다 유의하게 낮은 값을 나타내었다. GSH-Px, SOD 및 CAT의 활성치는 씀바귀추출물 투여군 들이 대조군보다 높은 값을 나타내었다. TNF-α, Apo-B, Apo-E 및 Leptin의 gene expression은 씀바귀추출물 투여군이 대조군보다 낮은 expression을 나타내었다. β-actin expression에 대한 TNF-α, Apo-B, Apo-E 및 Leptin의 gene expression의 비율은 TNF-α와 Apo-E는 대조군보다 씀바귀추출물 투여군 들이 낮은 경향을 보였으나, Apo-B 및 Leptin의 비율은 대조군을 비롯한 씀바귀추출물 투여군 들 간에 유의한 차이를 나타내지는 않았다. 이상의 결과들을 종합해보면, 씀바귀 추출물은 지질강하 및 항산화에 긍정적인 효과를 나타내었음을 시사해준다.
        384.
        2010.12 KCI 등재 서비스 종료(열람 제한)
        Chlorogenic acid, formed of an ester of caffeic acid and quinic acid, which is naturally abundant in many plant species, was used as a model O-dihydoxy phenolic compound. In the previous study, we have reported that the isolated constituent from Apocynum venetum leaves has an inhibitory effect on Cu2+-induced oxidative modification of low-density lipoprotein (LDL). Among them, chlorogenic acid showed the most potent anti-LDL oxidative activity than other compounds. For the reason, we investigated the inhibitory effect of the chlorogenic acid on Cu2+-induced oxidative modification of LDL, monitored a lag time in the conjugated-diene formation and TBARS formation, and measured TNBS free amino acid group, and form cell formation in vitro system. The TBARS- and diene- formation were strongly inhibited by chlorogenic acid (0~100 μg/ml) with dose dependent manner. On the other hand, TNBS reactive lysine amino groups on LDL oxidation were protected by chlorogenic acid- treated cell group. Therefore, chlorogenic acid inhibited to cholesterol accumulation in the isolated peritoneal macrophage.
        385.
        2010.06 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        햄버거 패티에 L. monocytogenes cocktail을 인위적으로 접종한 후 UV-C 조사 처리에 따른 저장 중 미생물 수 변화를 조사하였다. 햄버거 패티에 접종된 L. monocytogenes의 초기 균수가 6-7 log CFU/mL가 되게 하였고, 사용된 UV-C 조사선량은 1, 5, 10 kJ/이었으며 조사된 시료는 에서 7일 동안 저장하였다. UV-C 조사는 L. monocytogenes 수에 있어서 조사선량이 증가할수록 유의적으로
        386.
        2009.11 KCI 등재 서비스 종료(열람 제한)
        The aim of this research was to apply experimental design methodology in the optimization condition of electrochemical oxidation of Rhodamine B(RhB). The reactions of electrochemical oxidation were mathematically described as a function of parameters amounts of current, NaCl dosage, pH and time being modeled by the use of the central composite design, which was used for fitting quadratic response surface model. The application of response surface methodology using central composite design(CCD) technique yielded the following regression equation, which is an empirical relationship between the removal efficiency of RhB and test variable in actual variables: RhB removal (%) = 3.977 + 23.279․Current + 49.124․NaCl - 5.539․pH - 8.863 ․time - 22.710․Current․NaCl + 5.409․Current․time + 2.390․NaCl․time + 1.061․pH․time - 0.570․time2. The model predicted also agree with the experimentally observed result(R2 = 91.9%).
        387.
        2009.10 KCI 등재 서비스 종료(열람 제한)
        A novel pretreatment technique was applied to the conventional Pt/alumina catalyst to prepare for the highly efficient catalyst for the preferential oxidation of carbon monoxide in hydrogen-rich condition. Their performance was investigated by selective CO oxidation reaction. CO conversion with the oxygen-treated Pt/Alumina catalyst increased remarkably especially at the low temperature below 100℃. This result is promising for the normal operation of the proton exchange membrane fuel cell (PEMFC) without CO poisoning of the anode catalyst. XRD analysis results showed that metallic Pt peaks were not observed for the oxygen-treated catalyst. This implies that well dispersed small Pt particles exist on the catalyst. This result was confirmed by high resolution transmission electron microscopy (HRTEM) analysis. Consequently, it can be concluded that highly dispersed Pt nanoparticles could be prepared by the novel pretreatment technique and thus, CO conversion could be increased considerably especially at the low temperatures below 100℃.
        389.
        2009.04 KCI 등재 서비스 종료(열람 제한)
        In this study, the fundamental experiments were performed for catalytic oxidation of NO (50 ppm) on MnO2 in the presence of ozone. The experiments were carried out at various catalytic temperatures (30-120℃) and ozone concentrations (50-150 ppm) to investigate the behavior of NO oxidation. The honeycomb type MnO2 catalyst was rectangular with a cell density of 300 cells per squuare inch. Due to O3 injection, NO reacted with O3 to form NO2, which was adsorbed at the MnO2 surface. The excessive ozone was decomposed to O* onto the MnO2 catalyst bed, and then that O* was reacted with NO2 to form NO3-. It was found that the optimal O3/NO ratio for catalytic oxidation of NO on MnO2 was 2.0, and the NO removal efficiency on MnO2 was 83% at 30℃. As a result, NO was converted mainly to NO3-.
        390.
        2009.03 KCI 등재 서비스 종료(열람 제한)
        The blue-green algae which caused odor problem in the tap water are difficult to precipitate in sedimentation basin and clogged the filter void rapidly. The studies of this paper were not only oxidation, coagulation and sedimentation processes for effectively removing blue-green algae but yellow clay and polyamine for verification as coagulants aids. The results of this research are summarized as follows: Higher ozone dose(C) and longer contact time(T) were needed for a high degree of removing blue-green algae efficiency. the removal rate of blue-green algae was proportional to the C×T value. The removal percent of chlorophyll-a by sedimentation and filter without pre-ozonation was about 75% but 1 mg/L pre-ozonation could increase the removal percent of chlorophyll-a to 99% and more pre-ozonation could remove completely. Though the removal efficiency of turbidity could increased by high dose of chlorination, the dissolved organic carbon was increased. More chlorine dose from 4 to 10 mg/L dissolved organic carbon was decreased. Using yellow clay as coagulant aids increased density of floc so the settling velocity of floc become rising but polyamine could not increase settling velocity of floc though it could formated large floc.
        391.
        2008.12 KCI 등재 서비스 종료(열람 제한)
        Hydrogen gas is used as a fuel for the proton exchange membrane fuel cell (PEMFC). Trace amount of carbon monoxide present in the reformate H₂ gas can poison the anode of the PEMFC. Therefore, preferential oxidation (PROX) of CO is essential for reducing the concentration of CO from a hydrogen-rich reformate gas. In this study, conventional Pt/Al₂O₃catalyst was prepared for the preferential oxidation of CO. The effects of catalyst preparation method, additive, and hydrogen on the performances of PROX reaction of CO were investigated. Water treatment and addition of Ce enhanced catalytic activity of the Pt/Al₂O₃ catalyst at low temperature below 100℃.
        392.
        2008.08 KCI 등재 서비스 종료(열람 제한)
        The formation of ConTiOn+₂ compounds, i.e., CoTiO₃ and Co2TiO₄, in a 5 wt% CoOx/TiO2 catalyst after calcination at different temperatures has been characterized via scanning electron microscopy (SEM), Raman and X-ray photoelectron spectroscopy (XPS) measurements to verify our earlier model associated with Co3O4 nanoparticles present in the catalyst, and laboratory-synthesized ConTiOn+₂ chemicals have been employed to directly measure their activity profiles for CO oxidation at 100˚C. SEM measurements with the synthetic CoTiO₃ and Co2TiO₄ gave the respective tetragonal and rhombohedral morphology structures, in good agreement with the earlier XRD results. Weak Raman peaks at 239, 267 and 336 cm-1 appeared on 5 wt% CoOx/TiO₂ after calcination at 570oC but not on the catalyst calcined at 450˚C, and these peaks were observed for the ConTiOn+₂ compounds, particularly CoTiO3. All samples of the two cobalt titanate possessed O 1s XPS spectra comprised of strong peaks at 530.0±0.1 eV with a shoulder at a 532.2-eV binding energy. The O 1s structure at binding energies near 530.0 eV was shown for a sample of 5 wt% CoOx/TiO₂, irrespective to calcination temperature. The noticeable difference between the catalyst calcined at 450 and 570˚C is the 532.2 eV shoulder which was indicative of the formation of the ConTiOn+₂ compounds in the catalyst. No long-life activity maintenance of the synthetic ConTiOn+₂ compounds for CO oxidation at 100˚C was a good vehicle to strongly support the reason why the supported CoOx catalyst after calcination at 570˚C had been practically inactive for the oxidation reaction in our previous study; consequently, the earlier proposed model for the Co₃O₄ nanoparticles existing with the catalyst following calcination at different temperatures is very consistent with the characterization results and activity measurements with the cobalt titanates.
        393.
        2008.06 KCI 등재 서비스 종료(열람 제한)
        제주도 화산회 기원 토양시료들은 전형적인 안디졸에 해당하는데 낮은 pH, 높은 수분함량, 높은 유기물함량, 식질-미사질 토성을 보여주었다. 결정질 광물 중 현무암 기원의 감람석, 휘석 등의 철고토광물과 자철석 및 적철석 등의 산화철이 주구성광물로 관찰되며 이차광물인 깁사이트가 일부 심토에서 나타나는 것이 특징이다. 그밖에 제주도 화산회 토양은 비정질 알로판 광물과 ferrihydrite 등의 결정도가 낮은 광물을 상당량 포함하고 있다. 주성분원소는 비화산회토양에 비해 상대적으로 낮은 SiO2 함량과 높은 A12O3 및 Fe2O3 함량을 보이는데 이는 전형적인 화산회토의 특성을 반영한다. 토양 내 중금속 함량 중에서 Zn, Ni, Co, Cr은 각자 84~198, 56~414, 38~150, 132~1164 mg kg-1의 범위를 보여 일반적인 세계 토양 내 함량범위를 초과하는 것으로 나타났다. 특히 Cr의 경우 1,000 ppm 이상의 함량을 가지는 토양 시료도 존재하는 등 제주도 화산회 토양은 높은 Cr 함량을 보이는 것이 특징이다. 제주도 토양의 환원능은 평균 6.53 mg L-1 reduced Cr(VI)로서 내륙의 비화산회토양에 비해 5.1배 이상 큰 것으로 나타났다. 비화산회토양의 경우 토양 환원능은 토양의 이화학적 인자 중 총 탄소함량과 매우 좋은 상관관계(R = 0.90)를 보이고 있는 것으로 보고되었으나, 총 탄소함량이 일반 토양에 비해 20배 이상 큰 제주도 화산회 토양의 경우 환원능은 탄소함량과는 오히려 약한 음의 상관관계를 보여주고 있다(R = -0.469). 이러한 결과는 제주도 화산회 토양의 환원능을 제어하는 인자가 탄소함량뿐만 아니라 또 다른 토양 이화학성에 있음을 지시한다. 주성분 원소조성과 환원능의 상관관계분석결과 화산회토 특성을 반영하는 Al과 Fe 원소와 정의 상관관계(R = 0.793, R = 0.626)를 보여주었다. 또한 중금속 원소 중 Ni, Co, Cr 등은 제주도 화산회 토양의 환원능과 정의 상관관계(R = 0.538, R = 0.647, R = 0.468)를 보이고 있다. 산화환원전위에 민감한 Cr 원소의 경우 제주도 화산회토양의 높은 환원능으로 인해 유해하고 이동성이 높은 6가 크롬의 생성 및 이동이 매우 제한될 것으로 판단된다. 또한 제주도 화산회 토양의 환원능을 제어하는 인자는 비정질인 알로판 광물 및 ferrihydrite 등의 화산회토 특성과 밀접한 관련이 있는 것으로 판단된다.
        395.
        2008.03 KCI 등재 서비스 종료(열람 제한)
        This study based on electro-coagulation & oxidation reaction is applied to wastewater treatment. Electro-oxidation reaction is used to remove cyanide(CN) which is contained in plating wastewater. Cyanide is transferred by gases such as NH3, NOx, CO2. Analysis result and removal efficiency of Cyanide which is contained in heavy metal wastewater of plating plant, are shown as following paragraph. In electrode arrangement experiment, removal efficiency of carbon electrode(-)/STS316L electrode(+) arrangement method is superior to carbon electrode(-)/carbon electrode(+) arrangement method. Removal efficiencies of cyanide in different HRT such as 30 min, 45 min, 60 min, 75 min and 90 min are 85.5%, 93.1%, 98.0%, 98.7% and 99.4% respectively in carbon electrode(-)/STS316L electrode(+) arrangement method. Finally we can estimate the critical point at HRT of 60 min which the variation of removal efficiency is decreased and HRT to obtain removal efficiency of less than 1 ㎎/LCN is minimum 90 min.
        396.
        2008.02 KCI 등재 서비스 종료(열람 제한)
        The batch tests were performed to determine the ratio of Fenton reagent on diesel contaminated soil. The objective of a column test was to determine and optimize the hydrogen peroxide requirements for the remediation of a soil contaminated with diesel fuel. The batch test were done on 5 g diesel contaminated soil containing hydrogen peroxide (35%) and Iron (II) sulfate. The H2O2(g):Fe2+(g) ratio varied 1:0, 30:1, 15:1, 5:1, 1:1, with contact reaction time 120min. Initial diesel concentration were 2,000 mg/kg, 5,000 mg/kg, and 10,000 mg/kg. Average diesel removal from the contaminated soil is 97% after 2hrs. Results of this study showed possible application of without addition of iron source. In column test, treatment of a diesel-contaminated soil (initial diesel concentration: 2,000 mg/kg, 5,000 mg/kg, and 10,000 mg/kg) with hydrogen peroxide (35%) only was containing natural-occurring minerals. The time required for the column test was approximately 90min, 180min, 270min; column length was 5 cm, 10 cm, and 15 cm. The most effective stoichiometry (final diesel conc.: 200~300 mg/kg) of 0.2 g peroxide consumed/mg diesel degraded. Further investigation is required to identify the effect of soil organic matter and soil mineral.
        397.
        2007.12 KCI 등재 서비스 종료(열람 제한)
        Cobalt titanates (CoTiOx), such as CoTiO3 and Co2TiO4, have been synthesized via a solid-state reaction and characterized using X-ray diffraction (XRD) and X-ray photoelectron spectroscopic (XPS) measurement techniques, prior to being used for continuous wet trichloroethylene (TCE) oxidation at 36℃, to support our earlier chemical structure model for Co species in 5 wt% CoOx/TiO2 (fresh) and (spent) catalysts. Each XRD pattern for the synthesized CoTiO3 and Co2TiO4 was very close to those obtained from the respective standard XRD data files. The two CoTiOx samples gave Co 2p XPS spectra consisting of very strong main peaks for Co 2p3/2 and 2p1/2 with corresponding satellite structures at higher binding energies. The Co 2p3/2 main structure appeared at 781.3 eV for the CoTiO3, and it was indicated at 781.1 eV with the Co2TiO4. Not only could these binding energy values be very similar to that exhibited for the 5 wt% CoOx/TiO2 (fresh), but the spin-orbit splitting (ΔE) had also no noticeable difference between the cobalt titanates and a sample of the fresh catalyst. Neither of all the CoTiOx samples were active for the wet TCE oxidation, as expected, but a sample of pure Co3O4 had a good activity for this reaction. The earlier proposed model for the surface CoOx species existing with the fresh and spent catalysts is very consistent with the XPS characterization and activity measurements for the cobalt titanates.
        398.
        2007.08 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        본 연구는 진열중 조도 처리에 따른 재래종 돈육과 개량종 돈육의 지방산화 및 육색 안정성을 비교하고자 실시하였다. 평균 출하체중 66 kg의 재래종 돼지(거세돈) 5두와 112 kg인 개량종 돼지(, 거세돈) 5두를 도축하여 등심(M. longissimus) 부위를 에서 5일 동안 숙성한 다음 의 암실 및 3,000 lux에 7일 동안 진열하였다. 재래종이 개량종보다 높은 지방 함량을 가진 반면(p 함량을 가졌다(p
        399.
        2007.06 KCI 등재 서비스 종료(열람 제한)
        산채 자원의 발굴과 산업화를 위한 기초자료 확보 측면에서 산채 557종류에 대해 2006년 12월까지 발표된 국내 문헌을 중심으로 항균, 항산화, 항암 및 항당료성 산채의 종류와 내용을 조사하였다. 산채를 종류별로 나열 한 다음 항균, 항산화, 항암 및 항당료성 효과와 관련된 문헌을 표기함으로써 산채에 따른 연구 성과와 기능성 효과 파악에 크게 도움이 되었다. 문헌에 항균효과로 있는 것으로 나타난 산채 종류 수는 36종류(6.5%)였으며, 항산화 효과가 있는 것으로 나타난 것은 25종류(4.5%)였다. 문헌에 항암효과가 있는 것으로 산채 종류 수는 44종류(7.9%)였으며, 항당료 효과가 있는 것으로 나타난 것은 47종류(8.4%)였고, 기타 기능성 효과가 있는 것으로 나타난 것은 165종류(29.6%)였다.
        400.
        2007.03 KCI 등재 서비스 종료(열람 제한)
        Polycyclic aromatic hydrocarbons (PAHs) are a major concern because of their potential mutagenic and carcinogenic risks to human beings. One of these harmful, yet commonly observed PAHs is pyrene. Pyrene is one of the 16 PAHs listed by the United States Environmental Protection Agency as priority pollutants. The purposes of this research are to develop a method of pretreatment for PAH contaminants prior to a typical biological treatment and to demonstrate the biodegradablity of these compounds. Since pyrene is non-polar, hexane was chosen as a solvent to effectively dissolve pyrene. Pyrene solutions were treated with ozone, as it has high oxidation capacity and electrophilic character. The intermediates and byproducts of pyrene were dissolved in alkaline water at pH 11.4 and neutralized to test for BOD5, COD, and toxicity. These solutions were further ozonated and assessed of biodegradability. The first-order rate constant ko was found to be between 0.121day-1 and 0.081 day-1, depending on the duration of reozonation. The BOD5/COD ratio was found to 0.66. The toxicity test showed that after 10 min of reozonation time, the byproducts and intermediates of pyrene were within the non-toxic range of ± 10% inhibition for E-Coli bacteria.