• Title/Summary/Keyword: A_F Ratio

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A Study on the Slope Stability Analysis (사면(斜面)의 안정해석(安定解析)에 관(關)한 연구(硏究))

  • Kang, Yea Mook;Cho, Seung Seup
    • Korean Journal of Agricultural Science
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    • v.8 no.2
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    • pp.179-184
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    • 1981
  • This paper has been prepared to compare the safety factor of Fellenius method and Bishop method which are most frequantly utilized for stability analysis of dam and natural slope. The results are as follows. 1. Safety factor obtained by Bishop method shows 11-29% higher in steady seepage state and 46-57% higher in no seepage flow than the one by Fellenius. 2. The ratio of safety factor between no seepage flow and seepage flow ($F_1-F_2/F_2$) increases as the slope becomes flatter. 3. The ratio of safety factor between Bishop method and Fellenius ($F_B-F_F/F_F$) decreases as the slope becomes flatter.

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충돌형 가스발생기 탈설계점 연소시험

  • Kim, Seung-Han;Han, Yeung-Min;Seo, Seong-Hyeon;Moon, Il-Yoon;Lee, Kwang-Jin;Kim, Jong-Kyu;Seol, Woo-Seok
    • Aerospace Engineering and Technology
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    • v.3 no.2
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    • pp.81-90
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    • 2004
  • This paper describes the results of combustion performance test of fuel-rich gas generator(GG) using LOx and kerosene as propellant at off-design conditions. The chamber pressure is thought to be a function of O/F ratio and total propellant mass flow rate. The test shows that the spatial temperature deviation at the exit of gas generator remains within 7.5K and that the average gas temperature at the exit is a function of propellant O/F ratio. The results of firing test of gas generator at off-design conditions, especially the relation between gas temperature and O/F ratio, can provide useful data for the design of future gas generator and for the development of low-O/F ratio reaction analysis code.

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A study on the effects of intake port eccentricity and a partition between the two intake ports on the in-cylinder swirl characteristics in a valve diesel engine (4밸브 디젤기관의 흡기포트 편심과 두 흡기포트 사이의 격막이 실린더 내 선회 특성에 미치는 영향에 관한 연구)

  • Lee, Ji-Geun;Gang, Sin-Jae;No, Byeong-Jun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.7
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    • pp.948-961
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    • 1997
  • The effects of intake port eccentricity and a partition between the two intake ports on the incylinder swirl characteristics in a 4 valve diesel engine having the two intake ports, one is a helical intake port and the other is a tangential intake port, were investigated by using the impulse swirl meter(ISM) in a steady flow test rig. Mean flow coefficient ( $C_{f(mean)}$, swirl ratio ( $R_{s}$) and the mass flowrate through the two intake ports with and without intake port partition were measured. The results showed that the characteristics of in-cylinder swirl ratio formed by a 4-valve cylinder head were largely affected by valve eccentricity ratio ( $N_{y}$) and the existence of an intake port partition between the two intake ports. Mean flow coefficient ( $C_{f(mean)}$) increases and swirl ratio ( $R_{s}$) decreases in case of being the partition between the two intake ports. And also the mass flowrate through the tangential intake port is 19.0% and 7.7% more than that of the helical intake port in case of the two intake ports with and without partition respectively.ively.

Analysis of Fatigue Crack Growth with Thickness Ratio in Weldments (두께比를 考廬한 鎔接部의 疲勞龜裂傳播 解釋)

  • 차용훈;방한서;김덕중
    • Journal of Welding and Joining
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    • v.14 no.5
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    • pp.69-77
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    • 1996
  • This study aims to analyze the S. I. F. K value upon Mode I cracks in a finite-width plate of varying thickness, which is expressed in terms of width ratio ($\omega$), thickness ratio ($\beta$) and non-dimensional crack length (λ) by using the 2-dimensional finite element method. Then, by comparing the effectiveness of the results obtained by the two finite element methods, it is seen that the 2-dimensional finite element method can be used in order to analyse the S. I. F. K values upon a various thickness model. A model is developed in order to analyze the effects of initial residual stress upon the fatigue crack growth behavior in various thickness welded specimens. In this model, crack growth rate da/dN appears to be come small as the thickness ratio with the same ΔK is increased. Also, in the initial step, as ΔK is increased with crack growth rate is decreased and then increased because the repeated compressive residual stress retards crack growth rate.

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Optimum Lactose: Sucrose Ratio for the Pigs Weaned at 21 Days of Age

  • Jin, C.F.;Kim, J.H.;Han, In K.;Yeon, J.U.
    • Asian-Australasian Journal of Animal Sciences
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    • v.11 no.2
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    • pp.185-191
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    • 1998
  • A total of 240 weaned pigs (BW 5.4 kg) were allotted in a completely randomized block design to find out the optimum lactose : sucrose ratio for the weaned pigs. Treatments were 100:0 (A), 75:25 (B), 50:50 (C), 25:75 (D) and 0:100 (E) in lactose : sucrose ratio. For the first week after weaning, average daily gain (ADG) and feed/gain (F/G) were improved (p < 0.05) for pigs fed A, B and C diets compared to pigs fed diets D and E, but the average daily feed intakes (ADFI) of the pigs were not different. From d 7 to 14, no significant differences was found in ADG and ADFI among the treatments, but pigs fed the diets A, B and C had improved F/G compared with the pigs fed diets D and E (p < 0.05). From d 15 to 21, no significant differences were found in ADG, ADFI and F/G among the treatments. The digestibility of nutrients was not influenced by the lactose : sucrose ratio except nitrogen. Nitrogen digestibility of A diet was significantly higher than D and E diets (p < 0.05) but no significant differences were found among diets A, B and C. Dry matter and phosphorus excretions were not influenced by the treatments. The pigs fed diets A, B and C excreted significantly less nitrogen than the pigs fed diets D and E. In conclusion, the results suggest that sucrose can effectively replace up to 50% lactose in starter diets.

Efficiency factor of high calcium Class F fly ash in concrete

  • Sata, V.;Khammathit, P.;Chindaprasirt, P.
    • Computers and Concrete
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    • v.8 no.5
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    • pp.583-595
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    • 2011
  • This paper studied the cement efficiency factor (k factor) of high calcium Class F fly ash. This k factor represents a unit of fly ash with efficiency equivalent to k unit of cement. The high calcium Class F fly ash was used to replace cement in concrete. The modified Bolomey's law with linear relationship was used for the analysis of the result of compressive strength, cement to water ratio (c/w) and fly ash to water ratio (f/w) by using the multi-linear regression to determine the k factor and other constants in the equations. The results of analysis were compared with the results from other researcher and showed that the k factor of high calcium Class F fly ash depends on the fineness of fly ash, replacement level and curing age. While the amount of CaO content in Class F fly ash not evident. Furthermore, necessary criteria and variables for the determination of the k factor including the use of the k factor in concrete mix design containing fly ash were proposed.

Properties of fluorine-doped $SnO_2$ films prepared by the ultrasonic spray deposition (초음파분무법에 의해 제작된 $SnO_2(:F)$ 박막의 특성)

  • Byung Seok Yu;Sei Woong Yoo;Jeong Hoon Lee
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.4 no.3
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    • pp.294-305
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    • 1994
  • The influence of deposition parameter on the electrical, optical andsurface morphology of $SnO_2(:F)$ films prepared by ultrasonic spray deposition using DBDA and $SnCl_4.5H_2O$ as a source material was studied. Resistivity was decreased sharply with increasing F/Sn ratio in solution up to 0.6. Depending on the source material, $SnCl_4.5H_2O$ shows lower resistivity than DBDA. When F/Sn ratio in solution was 1, optical transmittance was higher DBDA than $SnCl_4.5H_2O$.

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Study on Sensitivity of Burst-Mode Optical Receiver Depending on Photodiode Capacitance (포토다이오드의 정전용량에 따른 버스트모드 광 수신소자의 수신감도 연구)

  • Lee, Jung-Moon;Kim, Chang-Bong
    • Korean Journal of Optics and Photonics
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    • v.19 no.5
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    • pp.343-348
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    • 2008
  • This study was carried out to commercialize FTTH by developing a burst mode optical receiver for E-PON. The optical receiver was manufactured by minimizing the capacitance of a photodiode to improve sensitivity for meeting 10, 20 km OLT Rx standard of E-PON at the transmission speed of 1.25 Gb/s. When bit-error ratio is $10^{-12}$ and PRBS is $2^5-1$, sensitivity is -26 dBm, loud/soft ratio is 23 dB. Both preamble time and guard time were set to 102.4 ns (128 bit). After comparing a photodiode whose capacitance is 0.53 pF with another photodiode whose capacitance has been minimized to 0.26 pF, we could see that sensitivity improved to 0.7 dBm and so did bandwidth to 190 MHz of burst mode for the optical receiver manufactured by the photodiode whose capacitance is 0.26 pF.

A Comparison of Parameters of Acoustic Vowel Space in Patients with Parkinson's Disease (파킨슨병 환자의 음향 모음 공간 파라미터 비교)

  • Kang, Young-Ae;Yoon, Kyu-Chul;Lee, Hak-Seung;Seong, Cheol-Jae
    • Phonetics and Speech Sciences
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    • v.2 no.4
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    • pp.185-192
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    • 2010
  • The acoustic vowel space has been used as an acoustic parameter in dysarthric speech. The aim of this work was to examine mathematical formulae for acoustic vowel space and to apply these to Korean speakers with idiopathic Parkinson's disease(IPD). Five acoustic parameters were chosen from earlier works and one new parameter was proposed, the pentagonal vowel space. The six parameters included triangular vowel space (3 area), irregular quadrilateral vowel space (4 area), irregular pentagonal vowel space (5 area), vowel articulatory index (VAI), formant centralization ratio (FCR) and F2i/F1u ratio (F2 ratio). An experimental group of 32 IPD patients(male:female=16:16) and a control group of twenty healthy people (male:female=8:12) participated in the study and repeated vowels (/a-i-u-e-o/) three times. A correlation analysis was performed among the six parameters, 2-way ANOVA was done with gender and groups as independent factors, and an independent sample t-test was conducted between the male and the female group as post hoc comparison. All parameters were highly correlated with each other and only the FCR showed a high negative correlation with the others. The results of ANOVA showed a significant difference in F2 ratio, 3 area, 4 area and 5 area between gender and in 4 area and 5 area between groups. For the male members of the two groups, significant statistical differences were found in all parameters whereas no such differences were found for the female members. These findings indicated that the vowel space of the female group was wider than the vowel space of the male group. These differences may have been caused by gender-specific speech styles rather than by patho-physiological mechanisms. We also claim that the pentagonal vowel space is better than the other vowel spaces at representing the disordered speech in natural speech situations.

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The Mechanical Properties of Concrete Usinga Large Amount of Fly Ash for Replacement Method (치환방법에 따른 플라이애쉬를 다량 치환한 콘크리트의 공학적 특성)

  • Kim, Tae-Wan;Kim, Tae-Sik;Jin, Chi-Sup
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.10 no.6
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    • pp.105-113
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    • 2006
  • This paper presents the results of an experimental investigation carried out to evaluate the mechanical properties of concrete mixtures in which fine(S) and coarse(G) aggregate was fully replaced with fly ash(FA). And flowability reduction problem in a large amount of fly ash concrete settled addition water($W_f$) in concrete mixture. In the test, water-cement ratio($W_c/C$) was 0.35, 0.45, and water-fly ash ratio($W_f/FA$) was 0.35, 0.45. The fly ash replacement is two different method of P and Q. The P method is mix property that the fly ash and addition water($W_f$) weight is equal to the aggregate weight [ $FA+W_f$ = G (or S)]. The Q method is mix property that fly ash is equal to aggregate weight, and added addition water($W_f$) [$FA+W_f$ > G (or S)]. Test were performed for properties of fresh concrete and compressive strength were determined at 3, 7, 28 and 91 days. The result, compressive strength was improvement that $W_c/C=0.35$, $W_f/FA=0.35$ and fine aggregate replacement in P method series than others. The flowability at Q method was improvement result than P method, but compressive strength was not. Test results indicate significant improvement in the strength properties and flowability of plain concrete by the inclusion of fly ash as fully replacement of fine and coarse aggregate, and can be effectively the fly ash replacement method.