• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.130-135
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• 1995

We can consider that the study on early evaluation of strength of concrete is useful to raise safety of building and utility of quality control of concrete is useful to raise safety of building and utility of quality control of concrete. In this paper, was proposed to method early to predict strength of concrete with key parameters, such as Water/Cement(W/C) ratio and Sand / Aggregate(S/A) ratio. Through a series of experiment, the obtained results are summarized as follow. $\circled1$ The ratio of resistance was decteased as the increase of W/C ratio. $\circled2$ The maximum value for the ratio of resistance and compressive strength was presented in the case of 40% S/A ratio. $\circled3$ The relationship. of the ratio of resistance and compressive strength on 28days according to the change of W/C and S/A ratio is to be: $F_{28}=-0.00104R^2 + 2.263R - 935.5$ (W/C Ratio) $F_{28} = 0.007R^2 - 10.693R - 4269.1$ (S/A Ratio)

• Journal of the Korean Home Economics Association
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• v.36 no.10
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• pp.179-196
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• 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.

• The Korean Journal of Physiology
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• v.3 no.1
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• pp.19-28
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• 1969

Skin temperatures on 10 sites and rectal temperature at every 10 minutes, oxygen consumption at every 20 minutes were measured on 18 male subjects (ages between 14 and 47 years) after exposure to cold air at $15^{\circ}C$ for two hours in a climatic room. Total body fat measured by means of a skinfold method and ratio of body surface area (S) to body volume (V), S/V, were utilized as basis of observations. Surface area was calculated after DuBois equation and body volume was calculated by our original formula. In influencing on the heat loss from the body core to the cold environment, % fat showed inverse relations, whereas, S/V ratio showed direct relations. Thus these two factors acted antagonistically on the body heat loss. Local skin temperatures showed negative correlations with skinfold thickness on the same site, nemaly, on chest, r=-.567; on back, r=-.507; and on upper arm, r=-.353. The other 7 skin sites showed low correlations with % fat. Minimum mean weighted skin temperature (MWST) showed a negative correlation (r=-.443) with % fat, and showed no correlation with S/V ratio. Oxygen consumption in the cold air at $15^{\circ}C$ increased from the first measurement at 20 minutes after exposure and maintained the same increasing trend up to 120 minutes. ${\Delta}T_R$ was greater in tile lean subjects who showed a greater % change in oxygen consumption. The antagonistic actions of % fat and S/V ratio on the heat loss were manifested by observations as follows: minimum rectal temperature was higher In fat subjects (r=.600) and lower in subjects with a greater S/V ratio (=-.582), ${\Delta}T_R$ was smaller in fat subjects (r=-.738) and greater in subjects with a greater S/V ratio (r=.618). Temperature difference between body core and skin surface (minimum rectal temperature minus minimum MWST) showed a positive correlation with % fat (r=.600) and a negative correlation with S/V ratio (r=-.881). Decrease in the mean body temperature and heat debt, respectively, showed negative correlations with % fat and positive correlations with S/V ratio.

• Korean Journal of Ecology and Environment
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• v.47 no.1
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• pp.32-40
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• 2014

This study was conducted to evaluate the growth response of economical six leafy vegetables that are crown daisy, pak-choi and four kinds of lettuce (Red leaf lettuce, Green leaf lettuce, Head lettuce, Romaine lettuce) by light treatment of LED in plant factory. The light treatments were composed of red, blue, red+farred, red+blue, red+blue+white LEDs, irradiation time ratio of the red and blue LED per minute (1 : 1, 2 : 1, 5 : 1, 10 : 1), and duty ratio of mixed light (100%, 99%, 97%). The following results were obtained in different LED light sources treatments: Shoot biomass and S/R ratio of romaine lettuce were the highest under mixed red+blue LEDs. S/R ratio of head lettuce was higher under mixed red+blue+white LEDs than red+blue LEDs. The others showed no difference in LED light treatment. Shoot biomass, total biomass and S/R ratio of green lettuce, head lettuce and pak-choi were highest in the higher red ratio (5 : 1) on irradiation time of red : blue LED ratios. By the different duty ratio (red+blue and red+blue+white LEDs), Under the mixed light of red+blue, shoot and root biomass of crown daisy and romaine lettuce were high in duty ratio of 100% and 99%, and S/R ratio was highest in all the 6 kinds in duty ratio of 97%. All the 6 kinds showed a fine growth state in low duty ratio (97%). Green lettuce, romaine lettuce and pak-choi showed relatively high shoot biomass and total biomass in low duty ratio of 97% under the mixed light of red+blue+white. S/R ratio of romaine lettuce and head lettuce were highest in the duty ratio of 97% with red+blue+white LEDs. Thus, we can cultivate stably without reference to external factors, if we use appropriate light sources and light quality in closed-type plant factory.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.136-141
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• 1995

The early evaluation on strength of concrete is useful to achieve on quality control and improvement of properties of concrete. Especially, we could say that the confidence of construction is increased by the increase durability and safety building, due to early evaluation. In this study, was proposed to ultra-sonic pulse method as a early evaluation method for strength of concrete with main parameter, sush as W/C ratio and S/A ratio. The experiment results are summarized to follow as : $\circled1$ The ultra-sonic pulse was decreased as the increase of W/C ratio. $\circled2$ The maximum value for the ultra-sonic pulse velocity and compressive strength was presented in the case of 40% S/A ratio and these value was decreased as the change of S/A ratio over 40% $\circled1$ The relationship of the ultra-sonic pulse velocity and compressive strength on 28days according to the change of W/C and S/A ratio is to be: $F_{28} = -209193R^2 + 384417R - 1763441$(W/C Ratio) $F_{28} = 1726R^2 - 774R - 502 (S/A Ratio)

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.2
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• pp.123-136
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• 1992

A preliminary thermodynamic design model of two-evaporator refrigerator/freezer system is constructed. This system is based on Lorentz-Meutzner cycle using refrigerant mixtures. This model screens alternative refrigerant (R32, R125, R143a, R22, R134a, R152a, R124, R142b, R123) mixtures to select the best performance-giving refrigerant mixtures and its composition for the system. Also, it estimates the effects of cooling temperatures of intercoolers, evaporator's area ratio, cooling load ratio on the performance of the system. The COP of the system ranges from 1.4 to 1.6, which is superior to that of the single evaporator system charged with R12 by 13% to 29%. Among 15 mixtures, R22/R123, R143a/R123, R32/R142b, and R32/R124 (in the order of high COP) are most recommendable. For the case of R22/R123, R22 mass fraction more than 0.5(Load Ratio=1.0) or 0.7(Load Ratio=0.33) is recomended in order to replace R12 without reduction in volumetric capacity when keeping the compressor as the same one. COP has the highest value with X(R22)=0.7 and 0.8, respectively. For the case of R143a/R123, in the similar manner, mass fraction of R143a is more than 0.5 or 0.6 while best performance occurs at X(R143a)=0.8. Higher temperature intercooler is more important for the performance of the system than lower temperature intercooler. The area ratio of evaporators is roughly proportional to load ratio of the evaporators.

• Korean Journal of Human Ecology
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• v.4 no.1
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• pp.36-45
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• 2001

This study was performed to determine the changes of maternal iron status during pregnancy cross sectionally, and to evaluate the appropriateness of the cut-off points of hemoglobin (Hb). hematocrit (Hct), serum transferrin receptor (sTfR) and sTfR : ferritin ratio for assessing iron deficiency status based on serum ferritin level (< 12${\mu}g$/L). Serum Hb concentrations in the first trimester were significantly higher (p < 0.05) than those in the second and third trimester. Serum levels of iron and ferritin in the third trimester were significantly lower (p < 0.05) than those in the first and second trimester. On the other hand, sTfR:ferritin ratios in the third trimester were significantly higher (p < 0.05) than those in the first and second trimester. sTfR concentrations did not change significantly during pregnancy. The appropriate cut-off points of Hb were 11.5g/dL for whole period of pregnancy. 12.0g/dL for 1st trimester. and 11.5g/dL for both 2nd and 3rd trimester. The good cut-off points of Hct were 34% for whole period of pregnancy. 36% for 1st trimester. and 34% for both 2nd and 3rd trimester The suitable cut-off points of TIBC were 400${\mu}g$/dL for whole period of pregnancy. 360${\mu}g$/dL for 1st trimester, and 400${\mu}g$/dL for both 2nd and 3rd trimester. Any cut-off point of sTfR could not be selected because of its low sensitivity and specificity. The proper cut-off point of sTfR : ferritin ratio was 600 or 650 for all the periods determined except the first trimester. In conclusion, there were no reliable cut-off levels of sTfR and those of sTfR : ferritin ratio showed low specificity. The cut-off values of Hb and Hct for assessing iron deficiency were slightly higher than the values used to evaluate anemia. Thus, if appropriate cut-off levels were applied, Hb. Hct, or TIBC might be useful indices for evaluating iron deficiency as well as anemia.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.779-787
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• 2023

In the relationship between the shareholding ratio of National Pension Service (NPS) and the investee firm's value, this study examined the mediating effect of R&D expenditure which its increase can indirectly induce the increase of firm value, and examined the moderated mediation effect of the Stewardship Code implementation which pressures investee firms' to increase R&D expenditure and firm value. Using the Korean listed companies' data from 2016 to 2021, the analysis showed that the R&D expenditure had a partial mediation effect on the relationship between NPS's shareholding ratio and firm value. Also, the analysis showed that the NPS's Stewardship Code implementation had positive moderating effects on following relationships, one between NPS's shareholding ratio and R&D expenditure, and the other between NPS's shareholding ratio and firm value. In all, on the relationship between NPS's shareholding ratio and firm value, the R&D expenditure's mediation effect differs before and after the implementation of the stewardship code, which shows the moderated mediation effect.

• Proceedings of the KSCN Conference
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• 2000.11a
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• pp.62-62
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• 2000

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.6
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• pp.725-734
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• 1997

The effect of helical intake port geometry on in-cylinder swirl flow characteristics was studied. Two helical intake ports were selected to change swirl ratio, mean flow coefficient with the variation of valve lifts, valve eccentricity ratios and axial distance. The measurements were made by using an impulse swirl meter. The port B modified to increase the swirl ratio( $R_{s}$) had the tendency of the increased non-dimensional rig swirl ( $N_{r}$) distribution in comparison with that of the port A. And the $N_{r}$ distribution was remarkably improved at low valve lifts. The modification of the geometry to increase the swirl ratio ( $R_{s}$) in helical intake port resulted in the decrease of the mean flow coefficient ( $C_{f(mean)}$) regardless of valve eccentricity ratio ( $N_{y}$). And also non-dimensional rig swirl ( $N_{r}$) in the high valve lift affected the calculation of swirl ratio considerably.onsiderably.