• 대한가정학회지
• /
• 제36권10호
• /
• pp.179-196
• /
• 1998

The purpose of this study was to analyze the financial status of Korean elderly households to make a financial plan for retirement preparation. The sample obtained from 1997 KHPS, consisted of 326 households of 55-64 aged and 210 households of 65 and over aged. Statistics employed for the analysis were frequencies, percentile, univariate analysis and logistic analysis. And Lorenz curve and Gini coefficient were used to compare the financial status. The results could be summarized as follows. First, total income, total expenditure, total debt and net worth of 55-64 aged group were higher than those of 65 and over group, while total asset of 55-64 aged group was similar to 65 and over group's Second, total expediture to total imcome ratio(R1) and total asset to total debt ratio(R4) of 55-64 aged group were higher than 65 and over group's, but net worth to minimum cost of living ratio(R2) and financial asset to monthly expenditure ratio(R3) of 65 and over group were higher than 55-64 aged group's . Third, R4's Gini coefficient was the highest and R1's Gini coefficient was the lowest among all Gini coefficients. Also, R1's and R4's Gini coefficients of 55-64 aged group were greater than 65 and over group's. ourth, variables affecting R1's stability of 55-64 aged group were household head's age, educatonal attainment and family type, while those of 65 and over group were household head's age, past economic experience and the number of children. There was no significant variable affecting R2's stability of 55-64 aged group, but there was only household head's pst economic experience affecting those of 65 and over group. The variable contributing to R3's stability of 55-64 aged group was residence while the variables of 65 and over group were household head's educational attainment, past economic experience and the number of children. The variables contributing to R4's stability of 55-64 aged group were the number of children and residence, and the number of children was one variable of contributing to R4's stability of 65 and over aged group.

• Nuclear Engineering and Technology
• /
• 제49권3호
• /
• pp.581-591
• /
• 2017

Influences of hold time and stress ratio on cyclic creep properties of Grade 91 steel were systemically investigated using a wide range of cyclic creep tests, which were performed with hold times (HTs) of 1 minute, 3 minutes, 5 minutes, 10 minutes, 20 minutes, and 30 minutes and stress ratios (R) of 0.5, 0.8, 0.85, 0.90, and 0.95 under tension loading cycles at $600^{\circ}C$. Under the influence of HT, the rupture time increased to HT = 5 minutes at R = 0.90 and R = 0.95, but there was no influence at R = 0.50, 0.80, and 0.85. The creep rate was constant regardless of an increase in the HT, except for the case of HT = 5 minutes at R = 0.90 and R = 0.95. Under the influence of stress ratio, the rupture time increased with an increase in the stress ratio, but the creep rate decreased. The cyclic creep led to a reduction in the rupture time and an acceleration in the creep rate compared with the case of monotonic creep. Cyclic creep was found to depend dominantly on the stress ratio rather than on the HT. Fracture surfaces displayed transgranular fractures resulting from microvoid coalescence, and the amount of microvoids increased with an increase in the stress ratio. Enhanced coarsening of the precipitates in the cyclic creep test specimens was found under all conditions.

• 한국해양공학회지
• /
• 제9권1호
• /
• pp.92-100
• /
• 1995

The effect of different anisotropy and stress ratio on fatigue crack propagation behavior was investigated under various stress ratio(R=-0.4, -0.2, 0.2, 0.2, 0.4) using pure titanium sheet used in aerospace, chemical and food industry. The rack closure behavior under constant load amplitude fatigue crack propagation test was examined. Fatigue crack propagation rate da/dN was estimated in terms of effective stress intensity factor range, $\Delta$K$_{eff}$, regardless of various stress ratio but was influenced by anisotropy. Also, it was found that the effect of anisotropy was considerably decreased but still not negligible when he da/dN was evaluated by a conventional parameter, $\Delta$$K_{eff}$/E and when the modified da/dN.$\sqrt{\varepsilon}_f$ was evaluated by $\Delta$$K_{eff}$/E. On the other hand, da/dN could be evaluated uniquely by effective new parameter, $\Delta$K$_{eff}$/$sigma_{ys}$, regardless of anisotropy, as int he following equation da/dN=C''[\frac{{\Delta}K_{eff}}{{\sigma}_{ys}}]^{n''}. And effective stress intensity factor range ratio, U was estimated by the following equation with respect to the ratio of reversed plastic zone size, $\Delta r_{p}$ to monotonic plastic zone size, $r_p$ regardless of stress ratio and anisotropy. U=-4.45$(\Delta r_{p}/r_{p})^{2}$+4.1$(\Delta r_{p}/r_{p})$+0.245_{p})$+0.245

• 생태와환경
• /
• 제53권3호
• /
• pp.304-310
• /
• 2020

Smart farm is a high-tech type of plant factory that artificially makes environmental conditions suitable for the growth of plants and manages them to automatically produce the desired plants regardless of seasons or space. This study was conducted by identifying the effects of Hertz and Duty ratio on the photosynthetic rate of ginseng, a medicinal crop, to find the optimal conditions for photosynthetic responses in smart farms. The light sources consisted of a total of 10 chambers using LED system, with 4 R+B(red+blue) mixed lights and 6 R+B+W (red+blue+white) mixed lights. In addition, the Hertz of the R+B mixed light was treated at 20, 60, 180, 540, 1620 and 4860 hz respectively. The R+B+W mixed light was treated with 60, 180, 540, and 1620 hz. Afterwards, experiments were conducted with the duty ratio of 30, 50, and 70%. As a result, the photosynthetic rate of ginseng according to duty ratio and Hertz was the highest at 60 hz when duty ratio was set to 50%. On the other hand, that was the lowest when the duty ratio was 30% at the same 60 hz. In addition, the photosynthetic rates were highest in the R+B mixed light and R+B+W mixed light at 60 hz. Therefore, the condition with the highest photosynthetic rate of ginseng in smart farms is 60 hz when the duty ratio in R+B mixed light is 50%.

• 한국잠사곤충학회지
• /
• 제39권1호
• /
• pp.62-66
• /
• 1997

The MAA graftings in silk fiber were done by redox system for the purpose of investingating the effect of ferrous sulfate additive on the grafting rate and graft ratio in various conditions. The graft ratio was higher in redox graft system than in peroxide graft system and the graft ratio in redox graft system was also higher depending on decrease of ferrous sulfate additive. The saturation graft ratio obtained by empirical equation, log X=K/t, was increasing depending on the increase of ferrous sulfate additive. Initial grafting rate was increased but the latter grafting rate was decreased in redox graft system. The effects of liquor ratio(L.R.) on the graft ratio in redox graft system, were higher in high L.R. than in low L.R..

• 한국정밀공학회지
• /
• 제20권3호
• /
• pp.172-177
• /
• 2003

This paper investigates the effect of reinforced plate on the deflection of the rectangular plate, when the rectangular plate is reinforced with rectangular rigid body at the centroid of the plate. For two boundary conditions such as simple supported and clamped boundary This study derives deflection formula of reinforced plates with three kinds of the aspect ratio of a rectangular plate with respect to the elastic modulus ratio and the length ratio of rigid body using the least square method. The results are as follows: 1. As the elastic modulus ratio r$_{e}$$\geq$ 1000, the maximum deflection with respect to the length ratio r$_{1}$ converges into constant value. 2. Deflection formula with respect to the length ratio r$_{1}$ is derived as the third order polynomial.l.

• Journal of Information Display
• /
• 제1권1호
• /
• pp.3-8
• /
• 2000

We have developed a high performance vertical alignment TFT-LCD (Thin Film Transistor Liquid Crystal Display), that shows a high light transmittance, and wide viewing angle characteristics with an unusually high contrast ratio. In order to optimize the electro-optical properties we have studied the effect of cell parameters, multi-domain structure and retardation film compensation. With the optimized cell parameters and process conditions, we have achieved a 24" wide UXGA TFTLCD monitor (16:10 aspect ratio 1920X1200) showing a contrast ratio of over 500:1, panel transmittance near 4.5%, response time near 25 ms, and viewing angle higher than 80 degree in all directions.

• 대한안전경영과학회지
• /
• 제11권3호
• /
• pp.209-216
• /
• 2009

A development in method of evaluating the measurement precisions using approximate F tests and variance components from expected mean square (EMS) is investigated. The research proposes three-factor mixed measurement models with the fixed and random factors. Unrestricted and unconstrained design work was rarely studied, while restricted and constrained designs have been significantly discussed. The unrestricted and unconstrained designs assume to be an independence of interaction. The proposed evaluation method about the measurement precisions can be extended to four-factor random measurement model or mixed measurement model. The study also presents the three evaluation indexes of precisions such as R&RTR (Reproducibility & Repeatability-To-Total Precision Ratio), PTR (Precision-To-Tolerance Ratio), and SNR (Signal-To-Noise Ratio). Numerical examples are proposed to evaluate the approximate F tests with Satterthwaite degrees of freedom and three indexes using the measurement precisions from EMS.

• 산업기술연구
• /
• 제20권B호
• /
• pp.15-20
• /
• 2000

High pressure, pressure ratio, refrigerating effect, heat transfer from the condenser and the power of the compressor etc. of a self-made refrigeration equipment for R-12 are investigated when R-12 and R-134a are used as the coolants. The comparison between the performance for R-12 and that for R-134a is made. As a result, R-134a is better than R-12 in the view of high pressure, refrigerating effect and the coefficient of performance and vice versa in the view of pressure ratio, exit gas temperature from the compressor and heat transfer from the condenser.

• 한국마린엔지니어링학회:학술대회논문집
• /
• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
• /
• pp.224-225
• /
• 2005

The lightness of components required on marine and shipbuilding industry is requiring high strength of components. In particular, fatigue failure phenomena, which happen in metal, bring on danger in human life and property. Therefore, antifatigue failure technology takes an important part of current industries. In this study, it was investigated about endurance and fatigue crack propagation rate of according to stress ratio of SMAW commonly using for welding structures in present. Fatigue crack propagation rate(da/dN) of low load(R=0.1) was lower than of high load(R=0.6) for piping weld. And in stage I, ${\Delta}$Kth, the threshold stress intensity factor of the weld under heavy load is higher than under small load. Fatigue life shows more improvement in the weld of stress ratio R=0.l than in the weld of stress ratio R=0.6.