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        검색결과 289

        41.
        2004.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The effect of La promoter on the carbon deposition and catalytic activity in the synthesis gas production with supported Ni catalysts was investigated. Active component was Ni and support was CeO2 and the promoter used was La. The reaction was carried out in a fixed bed reactor at 1 atm and 650~800℃. The catalysts were prepared by two methods, the impregnation method and urea method. The catalysts prepared by the urea method showed 10 times higher surface area than those of prepared by the impregnation method. By the introduction of La promoter in the catalyst system, carbon deposition was remarkably reduced from 16% to 2%. It appears that the promoter facilitates the formation of a stable fluoride-type phase, which reduces the carbon deposition. The best catalytic activity and CO and H2 selectivities were obtained with 2.5wt% Ni/Ce(La)Ox catalyst at 750℃, giving 90% methane conversion, 93 and.80% of CO and H2 selectivities, respectively.
        4,000원
        42.
        2004.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The effects of reaction temperature and flow rate of reactants on the methane conversion, product selectivity, product ratio, and carbon deposition were investigated with 13wt% Ni/MgO catalyst. Reaction temperatures were changed from 600 to 850℃, and reactants flow rates were changed from 100 to 200 mL/mim. There were no significant changes in the methane conversion observed in the range of temperatures used. It is possibly stemmed from the nearly total exhaustion of oxygen introduced. The selectiveties of hydrogen and carbon monoxide did not largely depend on the reaction temperature. The selectivities of hydrogen and carbon monoxide were 96 and 90%, respectively. Carbon deposition observed was the smallest at 750℃ and the largest at 850℃. It is found that the proper reaction temperature is 750℃. The best reactant flow rate was 150 ml/min.
        4,000원
        43.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Synthesis gas is produced commercially by a steam reforming process. However, the process is highly endothermic and energy intensive. Thus, this study was conducted to produce synthesis gas by the partial oxidation of methane to cut down the energy cost. Supported Ni catalysts were prepared by the impregnation method. To examine the activity of the catalysts, a differential fixed bed reactor was used, and the reaction was carried out at 750~850℃ and 1 atm. The fresh and used catalysts were characterized by XRD, XPS, TGA and AAS. The highest catalytic activity was obtained with the 13wt% Ni/MgO catalyst, with which methane conversion was 81%, and H2 and CO selectivities were 94% and 93%, respectively. 13wt% Ni/MgO catalyst showed the best MgNiO2 solid solution state, which can explain the highest catalytic activity of the 13wt% Ni/MgO catalyst.
        4,000원
        44.
        2003.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Synthesis gas is commercially produced by a steam reforming process. However, the process is highly endothermic and energy-consuming. Thus, this study was conducted to produce synthesis gas by the partial oxidation of methane to decrease the energy cost. Supported Ni catalysts were prepared by the impregnation method. To examine the activity of the catalysts, a differential fixed bed reactor was used, and the reaction was carried out at 750~850℃ and 1 atm. The fresh and used catalysts were characterized by XRD, XPS, TGA and AAS. The highest catalytic activity was obtained with the 13wt% Ni/MgO catalyst, with which methane conversion was 81%, and H2 and CO selectivities were 94% and 93%, respectively. 13wt% Ni/MgO catalyst showed the best MgNiO2 solid solution state, which can explain the highest catalytic activity of the 13wt% Ni/MgO catalyst.
        4,000원
        46.
        2003.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to prepare a softener, alkyl imidazoline salt, fatty carbamide salt, and fatty polyamide salt were synthesized first, and then the synthesized salts were blended. The prepared softeners were applied to acrylic fibers, and then several properties were tested. As a result, the prepared softeners show good softening and lubricating properties, and they also show a little antistatic property. Through bending resistance tests and measurements of feeling change of acrylic fibers treated with the softeners, it was proved that the prepared softeners are durable softeners.
        4,000원
        51.
        1998.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Mg2SiO4 열형광체에 란탄계 금속 Tb, Tm, La, Ho, Dy 및 Nd를 활성체로 첨가하여 열형광체를 제작했으며, Peak shape법으로 활성화에너지를 계산한 결과 0.53-1.77eV였으며, 발광과정의 차수는 전부 2차였다. 저 에너지 X-선에 대해 매우 높은 감도를 나타내었으므로 방사선 센서 소자로 개발하기 위한 기초 자료가 될 것이다.
        4,000원
        52.
        1998.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        MgB4O7 열형광체의 활성체는 란탄계 금속인 Tb, Tm, Dy, La, Ho 및 Nd를 첨가하여 580˚C의 Ar 분위기에서 2시간동안 소결하여 제작하였다. 활성화에너지와 glow 곡선의 주 Peak의 세기는 peak shape법과 초기상승법의 두방법에 의해 결정했으며, 최적활성에너지는 0.76±0.02eV(Tm 첨가시), 0.94±0.03eV(Tm 첨가시) 및 0.72±0.02eV(Dy 첨가시)였다. 이들 열형광체들은 저 에너지 X-선에 대해 매우 높은 감도를 나타냈으므로 방사선 센서 소자로 개발하기 위한 기초자료가 될 것으로 생각된다.
        4,000원
        53.
        1995.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the study, attempts were made to investigate the safety of the deep-fried instant noodles. A total of 50 deep-fried instant noodles were puchased from a local supermarket. Acid value, peroxide value, preservatives, heavy metals and pesticide residues were determined. Acid value(AV) and peroxide value(POV) of deep-fried instant noodles were lower than the Food Law in force. Any preservatives were not detected in all deep-fried instant noodles. The level of all heavy metals and pesticide residues found in deep-fried instant noodles were fairly low, and pesticide residues in deep-fried instant noodles was almost removed after cooking. It was conclued from these results that deep-fried instant noodles may be no harmful in oxidative stability(AV, POV) and sanitary safety(preservatives, heavy metals and pesticides).
        4,000원
        54.
        1993.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        탄소/탄소 복합재의 산화 저항성을 개선시키기 위하여 aluminum iso propoxide및 aluminum tri sec butoxide졸을 2D-탄소/탄소 복합재에 도포하여 산호 억제층으로서의 효과를 관찰하였다. 촉매/알콕사이드의 몰비가 0.07, 물/알콕사이드의 몰비가 100일때의 산화 억제효과가 양호했으며, 승온속도를 20˚C/min로 하여 승온분석시험한 결과는 도포시편이 80˚C 정도의 산화 개시온도가 20%감소되는 시간을 측정한 TGA분석에서는 도포시편이 20% 정도의 산화 저항성 개선효과를 나타냈다. 도포막의 두께는 1회 도포막이 3μm, 2회 및 3회 도포막이 4-5μm 정도였고, 열충격 시험은 횟수에 따라 산화량이 증자하였다. 5% 전환률에서의 도포하지 않은 시편의 활성화 에너지는 33.2Kcal/mole이었으며 도포시편의 활성화 에너지는 37.1Kcal/mole이었다.
        4,000원
        58.
        2020.04 KCI 등재 서비스 종료(열람 제한)
        본 실험은 일당귀의 개화 후 일수에 따른 종자 등숙 특성을 알아보고자 수행하였다. 2019년 농촌진흥청 약용작물과 시험 포장에서 채종한 종자를 시험재료로 사용하였다. 개화 후 일수에 따라 종자 무게와 발아율이 조사되었고, 등숙 과정 동안 종자 내에서 배종비(E:S ratio)가 측정되었다. 결과적으로는 각 소화서마다 개화 후 일수가 증가할수록 종자 무게가 유의적으로 증가하였으며, 각 소화서에서 발아가 시작되는 시기는 차이가 있었다. 또한 종자 내에서 배의 길이는 계속해서 성장하여 배종비가 높아지는 것을 관찰하였다. 일당귀는 다양한 소화서에서 꽃이 피기 때문에 종자의 배종비가 종자 발아에 영향을 미칠 수 있다. 본 연구를 바탕으로 일당귀의 우량 종자 생산을 위해서는 개화 후 50일부터 70일경이 가장 적합한 것으로 사료된다.
        59.
        2018.10 서비스 종료(열람 제한)
        Background : In previous study, we reported Sclerotium rot caused by Sclerotium rolfsii in Ixeridium dentatum for the first time. This experiment was conducted to select highly effective pesticides against Sclerotium rot caused by S. rolfsii in I. dentatum. Methods and Results : The chemical efficacy and the injury test were carried out. A total of five pesticides were used for the experiment test. For the efficacy test, we investigated spore germination and mycelial growth inhibiting ability by each pesticides in vitro and disease inhibiting ability in the field. For the chemical injury, we investigated appearance of abnormalities on condition of reference amount and fold amount in the field. In vitro, three kinds of chemicals such as Fludioxonil suspension concentrate (SC), Tebuconazole suspension concentrate (SC), and Flutolanil emulsifiable concentrate (EC) showed complete spore germination inhibitory effect, However in two chemicals such as Pyraclostrobin water-dispersible granule (WG) and Pyribencarb suspension concentrate (SC), the mycelial growth inhibitory effect was partially recognized but the spore germination was not inhibited. In the field, we performed an artificial inoculation experiment using sclerotia. As a result four kinds of chemicals such as Fludioxonil SC, Tebuconazole SC, Flutolanil EC, and Pyraclostrobin WG showed control value of above 80% against Sclerotium rot caused by Sclerotium rolfsii except Pyribencarb SC. Also there was no chemical injury in reference amount and in fold amount respectively, compared to non treated control. Conclusion : From the above results, we selected four items of pesticides including Fludioxonil SC, Tebuconazole SC, Flutolanil EC, and Pyraclostrobin WG as effective chemicals against Sclerotium rot caused by Sclerotium rolfsii in Ixeridium dentatum.
        60.
        2018.10 서비스 종료(열람 제한)
        Background : In the process of developing new disease-resistant cultivar of Rehmannia glutinosa, it is essential to screen plants based on resistance to their disease. But until now, we have relied on visual inspection for selection of disease-resistant cultivar. Therefore, this experiment was carried out to establish an efficient and reliable screening system and test the resistance to leaf spot disease in R. glutinosa cultivars developed until now. Methods and Results : We have tested 11 R. glutinosa cultivars developed so far. Rootstock of R. glutinosa were sown in 20 × 20 ㎝ plastic square port and grown in green house at 25 ± 5℃ for four months and then cutting leaves were inoculated with Phoma sp. HCRD 17103 by spraying spore suspention of fungus at concentration of 1 × 107 spore/㎖. The inoculated leaves were incubated in a dew chamber at 25℃ for 48h and then transferred to glass house (25 ± 5℃, RH 80% ≥ ). After 3 - 5 days when the most susceptible cultivar had lesion area over 40%, disease severity of the cultivars was investigated on a scale of 0 - 9 (0 = healthy, 1 = 0 - 1%, 3 = 1.1 - 10%, 5 = 10.1 - 20%, 7 = 20.1 - 40%, 9 = 40.1% over). The degree of resistance was determined according to the disease index (0 and 1 = resistant, 3 = moderately resistant, 5, 7 and 9 = susceptible). As a result of experiments according to the above criteria, the disease index of cultivar Gogang, Dagang, Segang, Yeongang, Wongang, and Dahwang was 1, cultivar Togang, Daegyung, Jiwhang 1 and Goryeo was 3, cultivar Hwanggang was 9, respectively. Conclusion : From the above results, six cultivars such as Gogang, Dagang, Segang, Yeongang, Wongang, and Dahwang were resistant, four cultivar such as Togang, Daegyung, Jiwhang 1 and Goryeo were moderately resistant, and only one cultivar Hwanggang was susceptible to the leaf spot disease by Phoma sp. This experiment used only leaves and we plan to use whole plants in the future to see more accurate resistance response.
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