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        검색결과 81

        41.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to prepare high-solid coatings, first acrylic resins (HSAs) which contain 80% solid were synthesized, and then the prepared resins were cured with isocyanate at room temperature. In the synthesis of HSAs, viscosity, number average molecular weight (Mn) and conversion were 1372~2700 cps, 1520~1650 and 83~87%, respectively. Among the four kinds of initiators used, tert-amylperoxy-2-ethyl hexanoate was the most proper one in the synthesis of HSAs. With increasing Tg values, viscosity increased rapidly and molecular weight increased slowly. As a result of the examination of coated films, it was found that 60˚ specular gloss, impact resistance, heat resistance and cross-hatch adhesion were good, and pencil hardness, drying time and pot life were poor.
        4,000원
        42.
        2006.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Methanol and formaldehyde were produced directly by the partial oxidation of methane over mixed oxide catalysts. The catalysts were composed of Mo and Bi with late-transition metals, such as Mn, Fe, and Co. The reaction was carried out at 450℃, 50 bar in a fixed-bed differential reactor. The prepared catalysts were characterized by O2-TPD and BET apparatus. Among the catalysts used, the catalyst composed of 1:1:2.5 molar ratio of Mo:Bi:Mn showed the best methane conversion and methanol selectivity. The change in ratio of methane to oxygen affected at the conversion and selectivity, and the most proper ratio was 10:1.5. Methane conversion, methanol and formaldehyde selectivities increased with the surface areas of the catalysts. From the O2-TPD result, it was found that the oxygen species responsible for this reaction might be the lattice oxygen species desorbed at high temperature around 800℃.
        4,000원
        43.
        2006.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        청계천 복원공사 전(2003) 중(2004) 후(2005)의 수질과 식물 및 식생모니터링결과 청계천의 수질등급은 공사 전에는 BOD5가 평균 51.1mg/L로서 등급 외이었으나, 공사 후에 한강수와 지하철 역사의 물이 공급되면서 BOD5가 3.3mg/L로 낮아져 수질이 3등급으로 향상되었다. 식물의 경우는 공사 전에 총 121종에서 공사후에 132종으로 다소 증가하였다. 특히 다년초의 비율이 공사 전 24.8%에서 공사 후 35.6%로 증가되었으며, 갈대군락과 잔디군락이 도입식생으로 관찰되었다. 그러나 공사구간은 공사 전 우점 군락이었던 식생보전등급 1인 환삼덩굴과 망초군락이 여전히 우세하여 식물의 생태성은 공사전과 후의 변화가 크지 않았다. 또한 이 같은 조사내용을 비교대상구간과 비교하면 비교대상구간의 수질은 BOD5 0.8mg/L인 1등급으로 공사구간보다 양호하고, 식물종수도 154종으로 공사구간보다 다양할 뿐 아니라 귀화식물의 비율은 13%로서 공사구간의 28.8%보다 낮았다. 따라서 현재까지는 공사구간이 비교대상구간보다 생태적으로 떨어지는 것으로 평가된다. 그러나 하천복원이란 장기적이며 복합적인 과정으로서 본 연구 에서와 같은 단기조사만으로 복원의 효과성을 논할 수 없으며, 앞으로 장기간에 걸친 다른 주요항목에 대한조사도 병행되어야만 청계천 복원의 효과성을 검증할 수 있을 것이라고 사료된다.
        6,100원
        44.
        2006.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Acrylic adhesives for automobiles protection were prepared by emulsion polymerization. Monomers used were n-butyl acrylate(BA), acrylonitrile (AN), butyl methacrylate(BMA), glycidyl methacrylate(GMA), and acrylic acid (AA). Emulsifiers used were sodium lauryl sulfate and polyoxyethylene lauryl ether, which are an anionic emulsifier and a nonionic emulsifier respectively. Potassium persulfate was used as an initiator and polyvinyl alcohol was used as a stabilizer. Emulsion polymerization was carried out in a semi-batch reactor at 70℃ and agitation speed was kept at 200 rpm. Water resistance, heat resistance, acid resistance, alkali resistance and smoke resistance were examined. As a result, when each 0.03 mole of GMA and AA was introduced, the adhesion properties and various above mentioned resistances of the prepared adhesives were satisfied the standard for automobiles.
        4,000원
        45.
        2006.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to anticipate nitrate reduction state in tree through measurement of nitrate reductase activity (NRA) and investigate the effect of nitrogen concentrations (100, 200, 400, and 600 mg L-1) on growth, the nitrogen content of various tissue, and NRA of pear (Pyrus pyrifolia cv. Niitaka) seedlings in sand culture. Nutrient solutions used in this experiment were adjusted to pH 6.5 and fixed the ratio of ammonium and nitrate to 1:3 and trickle-irrigated 3 times a day. Tree height and dry weight of various organs in seedlings were higher in low nitrogen concentration (100 and 200 mg L-1) than in high nitrogen concentration (400 and 600 mg L-1). The shoot growth in 600 mg L-1 was extremely poor by nitrogen over supply. Increasing the nitrogen concentration, the concentration of nitrate-N in leaves and roots were insignificantly changed but that of stems increased. The accumulation of total and reduced nitrogen in all organs with increasing concentrations of nitrogen supply were increased at 30 days after treatment but those of all organs at 60 and 90 days after treatment were highest in 600 mg L-1, whereas there were no significant changes among other nitrogen concentration. The in vivo (+NO3-) NRA of all organs did not relate to nitrogen concentration but the in vivo (-NO3-) NRA of leaves except roots increased with increasing the nitrogen concentration. Therefore, the proper nitrogen concentration to promote growth and nitrate reduction of pear tree was 200 mg L-1.
        4,000원
        46.
        2006.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Methanol and formaldehyde were produced directly by the partial oxidation of methane. The catalysts used were mixed oxides of late-transition metals, such as Mn, Fe, Co, Ni and Cu. The reaction was carried out at 450℃, 50 bar in a fixed-bed differential reactor. The prepared catalysts were characterized by XRD, TPD and BET apparatus. Of the catalysts, A-Mn0.2-6, which contains 0.2 mole of Mn and calcined at 600℃, showed the best catalytic activity: 3.7% methane conversion, and 30 and 28% methanol and formaldehyde selectivities, respectively. The catalytic activity was changed with the content of Mn and the calcination temperature. Catalytic activity increased with the specific surface areas of the catalysts. With XRD, it was found that the structure of the catalysts are changed with calcination temperature. Through O2-TPD experiment, it was found that the catalysts showing good catalytic activity showed O2 desorption peak around 800℃.
        4,000원
        47.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Natto, one of Japanese traditional food is made from steamed whole soybeans fermented with Bacillus natto. In this study, the effects of Natto mucilage- feeding on griwth, organ weight and serum nitrogen compounds of rats were investigated. Male rats in Sprague-Dawley strain were fed on basal diets supplemented with aqueous Natto mucilage of several percentages for 10 weeks. Natto mucilage had no significant effects on the body and organ weights. The levels of GOT, GPT, LDH. and total bilirubin in serum of rats fed Natto mucilage diets were significantly lower than those in the control group ' The levels of total protein and albumin were higher than those in the control group. The level of calcium in serum indicates a growing tendency. but creatinine, uric acid, and BUN had declining. And the most component of free am1no acids in Natto mucilage were glutamin acid.
        4,000원
        48.
        2002.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Natto is a Japanese traditional food made from whole soybeans by the fermentation of Bacillus natto. The purpose of this study was to investigate the effect of Natto mucilage on lipid metabolism in rats. The levels of total cholesterol, LDL-cholesterol and triglyceride in serum of rats fed Natto mucilage diets were lower than those in control rats, but serum HDL-cholesterol and phospholipid were higher than those in control rats. The results indicate that Natto mucilage may have more beneficial roles in lipid metablism because it decreased serum cholesterol and increased bilirubin excretion.
        4,000원
        51.
        1999.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was performed to determine optimum level of ethanol intake with weanling male rats. The weanling rats and the experimental diets were divided into 5 groups, control, A, B, C, D group in according to the levels of ethanol intake for 10 weeks. In the result of their serum analyses, we suggest that an adequate intake of ethanol is 1.47ml/kg/day. If body weight of any man is 60kg, he can drink about 90ml(1.47*60=88.2) ethanol/day. It corresponds to 360ml [90=360*(25/100)] of 25% SOJU.
        4,000원
        53.
        1999.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was designed to examine the effect of Ω-3 fatty acid, linlenic acid, EPA, DHA on serum lipid and cytokines of male rats(Sprague-Dawley). Animals of 3 groups were administrated perilla oil, salmoon oil, and tuna oil of 0.4 ml/day for 8 weeks respectively. These oils were used for a source of linolenic acid, EPA and DHA. Ω-3 polyunsaturated fatty acid decreases significantly body weight, serum PGE2 content and serum cytokines content of the rat, and increases internal organs weight, specially liver weight and serum HDL-cholesterol level of the rat. In the results, authors propose to use perilla oil for source of effective Ω-3 poly-unsaturated fatty acid(linolenic acid) to Prevent cardiovascular and immune diseases.
        4,500원
        54.
        1997.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        성별, 직업, 성품, 생활양식이 전혀 다른 K43과 C45환자의 위 내시경적 소견과 치료방법을 논의하였다. K43은 잘못된 식습관과 스트레스에 의한 미란성 위염환자로서 제산제와 함께 H_2-수용체 길항제, H^+/K^+-pump 억제제, prostaglandin 제제, colloidal bismuth, sucralfate, prokinetics 등 전통적인 약물에서부터 부작용을 감소시킨 최근에 개발된 약물에 이르기까지 효과가 인정된 약물들을 폭넓게 사용하였으나 증상을 개선치 못하였으며, 임상병리 검사와 상복부 초음파 검사는 정상이었으나, 소화생리기능 검사에서 visceral hypersensitivity를 나타내었다. 그러나 C45는 평소에 두통으로 NSAIDs를 습관적으로 복용한 경험에 의하여 발생되었을 것으로 추정되는 전형적인 위·십이지장 궤양의 환자로서 H. pylori 박멸제와 함께 일반적인 소화성 궤양이 치료제로 활동기에서 치유기로 증상을 크게 완화시켰다. 특히 K43은 amitryptyline을 투여하였으나 난치성 환자로 남아 있다. 이러한 원인불명의 비궤양성 환자는 미국에서 해마다 15%씩 증가하는 추세에 있고 적절한 치료법도 없으며, 우리 나라에서는 통계치도 없는 실정인 점을 지적하고 싶다.
        4,000원
        55.
        1993.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 입계의 성질을 이용한 PTCR 재료에 입계 modifier로서 Bi2O3와 BN을 첨가하고 입계의 미세구조와 결함농도를 변화시켜 이에 따른 소결 및 전기적 특성변화를 TMA, XRD, 복합 임피던스방법 등을 이용하여 해석하였다. 실험 결과 Y이 도우핑된 BaTiO3 PTCR 재료에 Bi2O3를 첨가하였을때 약 0.1mol%까지 고용이 되는 것으로 밝혀졌다. Bi2O3를 고용한계 이하로 첨가시에는 생성되는 vacancy등의 결함으로 말미암아 Y-BaTiO3의 치밀화가 촉진되었으나, 그 이상 첨가하면 치밀화 뿐만 아니라 결정립 성장도 억제되었다.Bi2O3 결정립 내부에 Ba와 Ti vacancy가 동시에 생길 수 있어 고온저항이 높아짐을 알 수 있었다. BN은 BaTiO3에 고용이 되지 않는 것으로 밝혀졌으며 B2O/wub/3를 주성분으로한 액상형성으로 인하여 저온에서의 급격한 치밀화가 관찰되었다. 또 Ba-Y-Ti-B-O의 비정질 상이 tripie junction에 존재함으로서 상온저항이 크게 변화하였으며, PTCR jump도 높아졌다.
        4,000원
        56.
        1993.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        용해와 주조, 압출과 열처리 기술의개선으로 고강도, 고파괴인성의 AI-Li-Cu 합금(2090 AI합금)을 제조하였다. 또한 준 산업용 규모(20kg)의 잉고트 제조공정을 확립하기 위해서 (1)선 (2)기계적 성질들에 미치는 열처리 영향 (3) 인장시험, 파괴인성 시험(KIc) 및 피로균열 전파시계를 갖고 있으며 최종 제품의 인장강도는 최대시효 조건에서 534MPa부터 566MPa이었고 연신율은 9%에서 11.9%정도였다. C-T 시편을 이용한 파괴인성 시험 결과 최대시효 조건에서 평면변형 파괴인성 (KIc)값은 39MPa√m였고 미시효 조건에서는 23MPa√m였다. 또한 0.1, 0.3, 0.5의 하중비에서 피로균열 전파시험을 행하였을때 임계응력 확대계수(δKth)는 각각 6.0, 5.3, 4.3 MPa√m이었다.
        4,000원
        57.
        1992.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was separated and identified prostaglandin from garlic by TLC, HPLC, and Gc-Mass. In this experiment aimed at researching the effects of garic on body weight, and serum lipid, protein and glucose in male rats. The male rats applied in this work were 42 of Sprague-Dawley strain. In addition to basal diet, the worker administrated 4 groups of the experimental rats solutions which were 0.2 and 0.4ml of raw garlic juice, and of etanol garlic extract with together 2.5% cholesterol solution solved by corn oil for 8 weeks respectively. These results were as follows. 1. Separated and identified of Prostaglandin from garlic. 2. The growth rate of body weight and food efficiency ratio(FER) appeared to be more increased in the experimental groups administrated ethanol garlic extract than raw garlic juice. 3. The content of serum total cholesterol apperaded to be decreased in the experimental group administrated 0.4ml of ethanol garlic extract. 4. The level of serum HDL-cholesterol had a tendency to be more increased in all the experimental groups administrated garlic than control group. 5. The level of serum glucose appeared to be decreased in all the experimental groups administrated garlic, particularly ethanol garlic extract.
        4,500원
        58.
        1992.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To study effects of wild garlic on components of lipid and protein, blood glucose level, and cholinesterase activity in rat's serum, Sprague-Dawley strain of 40 male rats are divided into 5 groups which are Normal, Control, A, B, and C group. Normal group is fed only Basal diet, and Control group is fed Basal diet and 0.5ml/day of 2.5% cholesterol solution, In addition to a diet of control group, A group is fed 25% wild garlic flour, B group 0.5ml/2day of concentratded wild garlic juice, C group 0.5ml/2day of concentrated ethanol extract of wild garlic, After 8 weesk the rats were fasted for 12 hours, and then decapitated to collect blood. The results of analysis of the rat's serum were summarized as follows, 1. Wild garlic diet, specially ethanol extract has an influence on decreasing the level of total cholesterol and blood glucose in rat's serum, 2. HDL-cholesterol and phospholipid content of rat's serum are increased by wild garlic diet. Therefore I think that wild garlic is good food for preventing development of atherosclerosis and diabetes.
        4,000원
        59.
        1991.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The study was accomplished to know the effects of garlic on body weight, and serum lipid, protein and glucose in male rats. The rats applied in this study were Sprague-Dawley strain of 42. In addition to basal diet, they were fed together raw garlic juice or ethanol garlic extract with 2.5% cholesterol solution solved by corn oil for 8 weeks respectively. These results were as follows. 1. The growth rate and efficiency ratio appeared to be more increased in ethanol garlic extract groups than in raw garlic juice groups. 2. The content of serum total cholesterol appeared to be the most decreased in 0.4ml ethanol garlic extract group. 3. The level of serum HDL-cholesterol had a tendency to be increased in all garlic groups. 4. Albumin/Globulin ratio appeared to be more decreased in raw garlic juice groups than in ethanol gar lie extract groups. 5. The level of serum glucose appeared to be more decreased in ethanol garlic extract groups than in raw garlic juice groups. Therefore we think that garlic is able to have an effect on atherosclerosis and diabetes.
        4,000원
        60.
        1989.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of the study was to find an effect of phospholipid-free vegetable oils on the serum lipids and proteins of Sprague-Dawley rats. All experimental rats were fed ad libitum for 60days with the mixture of starch: casein: salt mixture: vitamin mixture (60:18:4:1) and at the same time fed administratively with 1 ml of soybean oil, corn oil and sesame oil bought in market as source of phospholipid-free vegetable oils(PFVO) and those extracted directly by and oil press as source of phospholipid-containing vegetable oils(PCVO) respectively. At the last day of experimental period, the rats were fasted for 12 hours and decaptitated to collect blood for analysis of serum lipid and protein. The results of this study were summerized as follows. 1. The supplementation of dietary phospholipid decrease food efficiency ratio and the growth rate of experimental rats. 2. The supplementation of dietary phospholipid improve correlation coefficient of body weight and organ weights. 3. The supplementation of dietary phospholipid increase the level of serum phosphatidylethanolamine. Therefore, I think that we must eat dietary phospholipid unpurified from vegetable oil to prevent development of atherosclerosis and fat liver.
        4,900원
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