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여러수준의 산성비가 고추씨의 발아율 및 모 생육에 미치는 영향
차병진,이재춘 충북대학교 농업과학기술연구소 1994 農業科學硏究 Vol.11 No.2
In the experiment to determine the effect of simulated acid rain(SAR) of various pH on the germination rate and the growth of Capsicum annum cv. Komyung(red pepper), the low pH of SAR accerlated the grrmination of the seeds even though the effect of pH was not statistically significant. After 10 days of SAR treatment, soil pH dropped to a great extent. There was, however, little change in tap water treatment(control) . In SAR of low pH(2.5, 3.0), soil pH was lower than that of control after 10 days of treatment, but, it became lower after 20 days of treatment in high pH(3.5, 4.0, 4.5) SAR. Visible symptoms caused by SAR were white spot and marginal necrosis of the leaves. The lower the pH of SAR, the more the number of spots per leaf and the number of spotted leaves. Decrease in pH of SAR increased the severity of damage and reduced the period that the first visible symptom appeared. Effect of SAR on the DW/FW ratio of red pepper seedlings was not significant. Either in dry weight or fresh weight, root/shoot ratio of the seedlings, however, varied significantly by the pH of SAR. That is to say, root growth of SAR-treated seedlings was inhibited compared to that of tap water-treated seedlings.
유동성 및 응축성 복합레진의 점탄성에 관한 유변학적 연구
조병훈,이인복,권혁춘,손호현,엄정문 대한치과보존학회 2000 Restorative Dentistry & Endodontics Vol.25 No.3
The purpose of this investigation was to observe the viscoelastic properties of five commercial flowable(Aeliteflo, Flow it, Revolution, Tetric flow, Compoglass flow) , three conventional hybrid(Z-100,Z-250,P-60) and two condensable(Synergy compact, SureFil) resin composites. A dynamic oscillatory shear test was done to evaluate the storage shear' modulus (G' ) , loss shear modulus(G") , loss tangent(tan δ) and complex viscosity(η* ) of the resin composites as a function of frequency dynamic frequency sweep test from 0.01 to 100 rad/s at 25℃ - by using Advanced Rheometric Exparusion SystemtARES) . To investigate the effect On the viscosity of resin composites of filler volume fraction, the filler weight % and volume % were measured by means of Archimedes' principle using a pyknometer. The results were as follows 1.The complex viscosity η* of flowable resins was lower than that of hybrid resins and significant differences were observed between brands. The complex viscosity η* of condensable resins was higher than that of hybrid resins. The order of complex viscosity η* at ω = 10 rad/s was as follows. Surefil, Synergy compact, P-60, Z-250, Z-100. Aeliteflo, Tetric flow, Compoglass flow, Flow it, Revolution. The relative complex viscosity of flowable resins compared to Z-100 was 0.04-0.56 but Surefil was 30.4 times higher than that of Z-100. 2.The storage shear modulus G' and the loss shear modulus G" of flowable resins were lower than those of hybrid resins but those of condensable resins were higher. The patterns of the change of loss tangent, tan δ of resin composites with increasing frequency were significantly different between brands.The phase angles,δ, ranged from 30.2-78.1˚at ω = 10 rad/s. 3.A11 composite resins represent pseudoplastic nature with increasing shear rate. 4.The complex shear modulus G* and the phase angle δ was represented by the frequency domain phaser form, G*( ω )= G* eIδ = G*〈 δ. The locus Of frequency domain phaser plots in a complex plane was a valuable method that represent the viscoelastic properties of composite resins. 5.There was no direct linear correlationship but a weak positive relation was observed between filler volume % or weight % and the viscosity of the resin composites.
多數의 不偏推定量을 合成하기 위한 알고리듬에 關한 硏究
林炳春 春川敎育大學 1986 論文集 Vol.26 No.-
This thesis concerns the linear combination of several or many unbiased estimates of success probability in Bernoulli trials under various sampling plans. Binomial, negative binomial, and their curtailed sampling plans are considered. The criteria combining them is to minimize the variance of resulting estimate which is also to be unbiased. Thus a mathematical model can be constructed, the objective function of which implies the minimization of the variance of combined unbiased estimate and the constraint of which implies the sum of weights equals to one. An algorithm finding approximated optimal values of weights is constructed and some examples are presented.
Copper billet열간압출의 정상상태 유한요소해석에 관한 연구
이춘만,전병우 國立 昌原大學校 産業技術硏究所 1999 産技硏論文集 Vol.13 No.-
This study is concerned with a study on steady-state finite element analysis of hot extrusion for copper billet. The design of extrusion dies is still an art rather than science. Die design for a new extrusion is developed from through in-plant trials. In the present paper, axisymmetric steady-state finite element simulation program is developed. Steady-state assumption is used for both the analyses of deformation and temperature. The developed program is effectively used to simulate two cases of extrusion processes. Distributions of temperature, effective strain rate, mean strain rate and mean stress are studied for an effective design of an extrusion die.