• 제목/요약/키워드: 50s and above

검색결과 1,423건 처리시간 0.033초

50[MHz] 이상의 대역폭을 갖는 OTA 설계 (The Design of OTA Which Has Band-width Above 50[MHz])

  • 김석;방준호;윤창훈;김동용
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1990년도 하계학술대회 논문집
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    • pp.525-528
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    • 1990
  • In this paper, a CMOS Operational Transconductance Amplifier (OTA) which is used for high-frequency operation has been designed and simulated by SPICE 2G program. To increase input linear range, the input stage is designed by cross-coupled pair. And the output stage insert buffer stage for the buffing and gain. The band-width of designed OTA is $50{\sim}60$ [MHz].

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Candida albicans에 대한 생약의 항진균성에 관한 연구(I) (Antifungal Actions of Crude Drug Water Extracts on Candida albicans(I))

  • 유승조;서정식
    • 생약학회지
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    • 제5권3호
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    • pp.147-154
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    • 1974
  • Some crude drugs in ancient literatures have been used as traditional therapeutic agent of leucorrhea mainly caused by Trichomonas vaginalis and Candida albicans. Sixty six kinds of crude drugs in ancient literatures and ten constituents were selected as sample drugs. Trichomycin standard was tested to compare with the above drugs. To determine the anti-fungal effect of these drugs on Candida albicans Yu 1200, a test organism, screening test was conducted. Antifungal activities of crude drug water extracts were observed by means of two test methods : firstly through the agar slant method and secondly the counting chamber method which was used for acknowledged drug agents upon the result of the agar slant method. And in order to improve the fungicidal effect, the organisms were stained with 0.02% methylene blue solution. The results of the above test indicated that Fritillariae Rhizoma has antifungal action in the concentration of 310mcg/ml, Coptidis Rhizoma in 620mcg/ml, Meliae Cortex, Scutellariae Radix both in 5,000mcg/ml. Baicalin, catechol among the pure isolated constituents inhibited in the range of 50mcg/ml. This score was based on 50% inhibition in comparison with amounts of control organisms. Rhei Rhizoma, Mori Radicis Cortex, Linderae Radix, and Amomi globosi Fructus showed the antifungal effect moderately in 5,000mcg/ml, and baicalein and pectolinarin in 50mcg/ml in the limit of between 35% and 50% antifungal activity. Staining with 0.02% methylene blue showed that any of the crude drug extracts was unable to stain the cells, but trichomycin in 0.86unit/ml able to stain 12% of the cells. This result means that crude drugs probably do not have fungicidal but fungistatic action.

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자갈비산 메커니즘 연구를 위한 고속철도차량 하부유동 계측 (Track Measurements of Strong Wind under High-speed Train to Investigate Ballast-flying Mechanism)

  • 권혁빈;박춘수;남성원;고태환
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2005년도 춘계학술대회 논문집
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    • pp.369-373
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    • 2005
  • To investigate the mechanism of ballast-flying phenomena by strong wind induced by high-speed trains, wind velocity in the vicinity of the track has been measured using 16-channel Kiel-probe array and detailed flow structure near the surface of the track has been analyzed. The position at which the underflow fully develop has been examined in order to assess the driving force of the turbulent flow under train and the results yields that the turbulent flow owing to the cavity of the inter-car as well as the friction force at the underbody of the train is the main reason of the strong wind under high-speed train. The preceding wind tunnel test results has been introduced to assess the probability of ballast-flying during the passage of the high-speed train by comparing the results from field-measuring. The results shows that when the G7 train as well as the KTX train runs at 300km/h, about 25m/s wind gust is induced just above the tie and the probability for small ballast under 50g to fly is about 50% when it is on the tie. If the G7 train runs at 350km/h, the wind gust just above the tie increases to 30m/s, therefore more radical countermeasure seems to be needed.

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충청지역 지층별 전단파속도와 N값의 상관관계 분석 (Analysis on Relation of S-wave Velocity and N Value for Stratums in Chungcheong Buk-do)

  • 도종남;황필재;정성래;천병식
    • 한국지반환경공학회 논문집
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    • 제12권10호
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    • pp.13-22
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    • 2011
  • 본 연구는 충청 지역에서 측정된 전단파 속도를 지층별로 점성토층, 사질토층, 자갈층, 풍화토층, 풍화암층으로 분류하여 표준관입시험 N값과 전단파 속도의 상관관계식을 제안하였으며, 참고적으로 풍화암층을 제외한 전체토층의 상관관계식을 도출하였다. 제안된 상관관계식은 국내외 기존 제안식을 고려하여 모두 멱함수로 산정하였으며 지반강도의 경우 N값이 50 이상일 경우에는 선형으로 환산하여 적용하였다. 금번 연구에서 제안한 관계식을 국내외 사례와 지층별로 비교 분석한 결과 점성토층, 사질토층, 자갈층, 풍화토층의 경우에는 유사한 특성을 보이고 있음을 알 수 있었다. 다만, 풍화암층에 대한 상관관계식의 경우 국내 관계식과 다소 낮은 결과치를 나타내는 차이가 있음을 확인하였다. 풍화암층의 경우 상관관계식 산정에 있어 N값이 50 이상일 경우는 선형으로 환산하여 적용함에 따라 지반 강도가 높은 지층인 풍화암층에서 차이가 발생한 것으로 파악된다.

감귤과 유자중의 펙틴질의 이화학적 성질 (Physicochemical Properties of Pectic Substances from Citrus Fruits)

  • 이헌주;이혜수
    • 한국식품조리과학회지
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    • 제6권1호
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    • pp.9-12
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    • 1990
  • This study was carried out in order to investigate the physicochemical properties of isolated pectic substances from Citron, Satsuma mandarin, Marumero, and Natsudaidai. Among varieties, Citron had the highest value of isnoluble pectin and Marumero had the hightest ratio of soluble pection. The total pectin contents isolated by 2% Sodium hexameta-phosphate(SHMP) varied in the range of 1.85% ~ 2.63%. Anhydrogalacturonic acid(AUA) contents were 78.64%~89.14% and were lower than commercial pectin. Isolated pectin contained above 7% methoxyl content and above 50% esterification. The apparent molecular weight of commercial pectin and isolated pectin were 72,000 and 42,000~46,000 respectively. Esterification and ester methoxyl content were the lowest and apparent molecular weight was the highest in Satsuma mandarin. Citron's values were a little higher in esterification and ester methoxyl content and lower in apparent molecular weight than the others.

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Bioelectrical Impedance Analysis at Popliteal Regions of Human Body using BIMS

  • Kim, J.H.;Kim, S.S.;Kim, S.H.;Baik, S.W.;Jeon, G.R.
    • 센서학회지
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    • 제25권1호
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    • pp.1-7
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    • 2016
  • Bioelectrical impedance (BI) at popliteal regions was measured using a bioelectrical impedance measurement system (BIMS), which employs the multi-frequency and the two-electrode method. Experiments were performed as follows. First, a constant AC current of $800{\mu}A$ was applied to the popliteal regions (left and right) and the BI was measured at eight different frequencies from 10 to 500 kHz. When the applied frequency greater than 50 kHz was applied to human's popliteal regions, the BI was decreased significantly. Logarithmic plot of impedance vs. frequency indicated two different mechanisms in the impedance phenomena before and after 50 kHz. Second, the relationship between resistance and reactance was obtained with respect to the applied frequency using BI (resistance and reactance) acquired from the popliteal regions. The phase angle (PA) was found to be strongly dependent on frequency. At 50 kHz, the PA at the right popliteal region was $7.8^{\circ}$ slightly larger than $7.6^{\circ}$ at the left popliteal region. Third, BI values of extracellular fluid (ECF) and intracellular fluid (ICF) were calculated using BIMS. At 10 kHz, the BI values of ECF at the left and right popliteal regions were $1664.14{\Omega}$ and $1614.08{\Omega}$, respectively. The BI values of ECF and ICF decreased sharply in the frequency range of 10 to 50 kHz, and gradually decreased up to 500 kHz. Logarithmic plot of BI vs. frequency shows that the BI of ICF decreased noticeably at high frequency above 300 kHz because of a large decrease in the capacitance of the cell membrane.

Diazidophenylmethane 유도체들의 가수분해반응 메카니즘에 대한 반응속도론적 연구 (Kinetics and Mechanism of the Hydrolysis of Diazidophenylmethane Derivatives)

  • 권기성;서지형;이용구
    • 대한화학회지
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    • 제41권6호
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    • pp.313-319
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    • 1997
  • Diazidophenylmethane 유도체들(X: p-H, $p-OCH_3,\;p-F,\;p-CH_3$)을 합성하여 25$^{\circ}C$의 50:50(v/v) MeOH/$H_2O$ 혼합용매(${\mu}=0.1$ : KCl)에서의 pH 변화에 따른 가수분해 반응 속도상수를 측정하여 유도된 반응속도식과 치환기효과, 용매효과, 염효과, 열역학적 활성화 파라미터, 그리고 생성물분석의 결과로부터 낮은 $pH(0{\leq}pH<2)$에서는 $S_N2_CA$, 중간 pH(2$S_N1$, 그리고 높은 $pH(12에서는 $S_N2$ 반응메카니즘을 각각 제안하였다.

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농촌주민의 흡연 및 음주 실태와 이에 영향을 미치는 요인분석 (An Analysis of Determinants of Smoking and Drinking of Community people in Rural area)

  • 남철현
    • 보건교육건강증진학회지
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    • 제6권1호
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    • pp.48-59
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    • 1989
  • The study was designed. to analyse the factors effecting to smoking and drinking of community people in rural area. The study has been surveyed through interviews by trained college students for 1,846 residents who live in rural area(Eup or Myun office is located)for 20days(from 3rd. to 22M. in August, 1988) The summary and conclusions are as follows. 1. The number of answers on the questionaires was 1846. And the percent of man was 55.7 %(woman 44.3 %). Among age group 20-29 years group with 30.4 % was larger than any other group. Anaverage age of answers was 38.6 years. 2.In the period of residence, 21.5 % of the residents lived within 5 years(This group was larger than any other group). In occupations, workers in agriculture and fishing was more than other job occupants. In education, the percent of high school graduates was 44.0 %(higher than any other group) 3.The smoking rate of rural residents was 41.8 %and man's smoking rate was 76.0 % (woman's smoking rate was 7.6 %). These rates were higher than the rates in 1985 (The smoking rate of nation was 32.0 %). First of all, woman's smoking rate increased rapidly 4.As for smoking amount, in male 52.8% of smokers smoked a cigarette case (20 cigarettes) in a day, and 16.9 % of smokers smoked more than one cigarette case. In female 42.5 % of woman smokers smoked a half case in a day and the rate of non-smokers diminished to 77.8 % 5.The rate of non-smokers in 21-29 years group was higher than any other group and a smoking rate increased as an age increased. However, a smoking amount decreased as an age increased. This suggests that people are more concerning about their health as their ages increase.. 6.The smoking rate of college graduates was 58.8 %(higher than any other group) and in a smoking amount 36.4 % of college graduates, 29.8 % of high school graduates smoked more than a cigarette case in a day. This shows that people in a higher education group smoke more than those in other groups. 7.As for non-smoking rate, students, service job workers, company employees, and teachers was 54.1%, 43.4%. 40.1% and 39.5%. respectively. As for smoking rate, workers in agriculture and fishing was the highest level of all job employees. Public officers smoked less than the workers in agriculture and the smoking rate of teachers was less than that of public officers. with regard to smoking amount. above one cigarette case in a day was 39.9 % in public officers, 39.2 % workers in agriculture and fishing, 37.9 % in businessmen, 34.2 % in teachers, 31.9 % in service job employees and 31.6 % in a company employees. 8.The variables which had an effect on smoking were sex (B=.1701), job(B=.1688), education(B=.1671), age(B=.1125). These variables were significant in P<0.05 statistically. Explanatory variance level was 19% 9.The drinking rate of community residents was 61.8% and man's drinking rate was 81.7%(woman's drinking rate was 38.9%). As drinking rate 18.0%(the highest rate) of man drinkers drank 3 bottles of beer in a general drinking and 12.1% of them drank more than 10 bottles. 12.1% (the highest rate)of woman drinkers drank 2 cups of beer. The rising rate of woman's drinking of alcohol was remarkable. 10.Each non-drinking rate of age groups was 27.6% (in 20-30 years group), 28.0% (in 30-39 years group), 28.9%(in 40-49 years group) and 32,6%(in 50-59 years group), 10,7%(the highest rate) of 20-29 and 30-39 years groups drank above 3 bottles. 7.5% of 20-29 years group and 7.7% of 30-39 years group drank above 10 bottles. In 40-49 years group, 14.4 % of them drank a bottle and 8.1% of them drank above 10 bottles. In 50-59years group, 14,2% of them drank 2 bottles and 5.3 % of them drank above 10 bottles. This shows that a drinking rate decresed as an age increased. 11.Non-drinking rate was higher as an education level was lower. Each non-drinking rate of non-educated group, elementary school group, middle school group and high school group was 41.0 % of high school graduates and 14.5 % of college graduates drank 3 bottles of beer. 9.7 %(the highest rate) of college graduates drank above 10 bottles, in general drinking. 12.Each non-drinking rate of businessmen, farmers, service job workers, and students was 31.3%, 28.2%, 26.8% and 25.9%. However, Each drinking rate of public officers, company employees and teachers was 73.3 %, 72.2 % and 68.4 %. This tells us that the drinking rate of mental workers is higher than that of physical workers. 14.9 % of farmers and 14.4 % of public officers drank 3 bottles at a time. 10.5 % of teachers and 9.9 % of public officers drank above 10 bottles. 13.The variables which affect on drinking were sex(B=.1545), education(B=.1476), job(B=.1064), and age(B=.1052). These variables were significant in the level of 0.05 % and explanatory variance level was 18 %. 14.Government have to educate people and demonstrate the health hazards caused by smoking and over-drinking. Especially, No-smoking campaign for woman and education not to over drink for professional job workers are necessary.

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SHS법에 의한 고온발열체용 $MoSi_2$의 합성 및 소결 (Synthesis and Sinteirng of $MoSi_2$ by SHS Process)

  • 이승재;장윤식;김인술;박홍채;오기동
    • 한국세라믹학회지
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    • 제32권9호
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    • pp.1085-1091
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    • 1995
  • Molybdenum disilicide (MoSi2) was synthesized from Mo, MoO3, Si and Al powders by self-propagating high temperature synthesis (SHS). The effect of processing parameters such as Mo/MoO3 molar ratio, Ar gas pressure in the reactor and pressing pressure of compacts in synthesis of MoSi2 were investigated. h-MoSi2 was transformed into t-MoSi2 with increasing the Mo/MoO3 mole ratio, and only t-MoSi2 phase was identified above 3.5 : 1 (molar ratio). The synthesized phases did not change with the variation of Ar gas pressure and pressing pressure of compacts. It was found that the combustion temperature was above 2,50$0^{\circ}C$. The products were separated into MoSi2 (s) and $\alpha$-Al2O3 by the difference of their specific grativities. Bending strength, hardness and density of sintered specimen exhibited 82 MPa, 5.368 GPa and 5.43 g/㎤, respectively.

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Grapefruit종자 추출물의 항균성에 관한 연구 (Studies on the Antimicrobial Activity of Grapefruit Seed Extract)

  • 최종덕;서일원;조성환
    • 한국수산과학회지
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    • 제23권4호
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    • pp.297-302
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    • 1990
  • Grapefruit seed extract(GFSE)의 여러가지 미생물에 대한 항균력과 물김치 저장 효과를 검토한 결과는 다음과 간다 1. GFSE의 세균류에 대한 항균력에서 Vibrio속은 50ppm, Bacillus cereus와 Staphylococcus aureus는 30ppm, Serratia속은 10ppm 이상에서 균의 증식이 억제되었다. 2. 세균중 패혈증 원인균으로 알려진 Vibrio vulnificus에 대한 항균성은 nutrient broth에서 GFSE 30ppm 농도까지는 증식을 확인할 수 있었으나 50ppm 이상의 첨가에서는 72시간까지 균의 증식을 볼 수 없었다. 그리고 $5\%$ skim milk에서의 본 균에 대한 GFSE 살균력을 실험한 결과 $5.2\times10^5$에서 저장 120시간 후에는 GFSE농도 0, 10, 30, 50 및 100ppm에서 각각 $9.6\times10^3,\;5.3\times10^3,\;5.6\times10^2$, 48, 35/ml로 감소되어 GFSE농도 50ppm 이상에서는 살균효과가 있음을 알 수 있었다. 3. 곰팡이류에 대한 항균력은 Aspergillus parasiticus가 100ppm, Asperillus versicolor 50, Penicillium funiculosum 100, Pyrenochaeta terrestris 30 그리고 Trichodema viride는 30ppm까지 증식하였으나 그 이상의 농도에서는 증식이 억제되었다. 4. 물김치에 GFSE를 각각 50, 100ppm 첨가하여$5^{\circ}C$$20^{\circ}C$에서 저장하면서 pH변화를 확인한 결과 $5^{\circ}C$에서는 20일과 25일, $20^{\circ}C$에서는 17일과 20일까지 pH변동이 거의 없어 물김치의 보존기간을 연장시킬 수 있었다.

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