• Journal of Welding and Joining
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• v.12 no.3
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• pp.82-89
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• 1994

In this paper the effect of stress ratio on the fatigue crack growth rate of aluminum alloy A5083-O was examined. The fatigue tests were carried out using CCT (center cracked tension) specimens and CT(compact tension) specimens which were subjected to 0.5 and -1.0 stress ratio respectively. The obtained results are as follows; 1) The $\DeltaK_{th}$ as the function of stress ratio R was introduced in evaluating the fatigue crack growth rate of A5083-O. 2) A new model evaluating the effect of stress ratio on the fatigue crack growth rate was developed over the region of low and high propagation rate.

• Journal of Aquaculture
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• v.18 no.2
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• pp.130-132
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• 2005

Genomics research has two ultimate applied goals: to Isolate and clone genes of economic importance for bio-technology and gene-assisted selection (GAS), and to locate and use markers for marker-assisted selection (MAS) in selective breeding programs. To this end, we have identified linked markers for feed conversion efficiency growth rate, and disease resistance to enteric septicemia of catfish (ESC). Three microsatellite markers Ip266, Ip384, and Ip607 were identified to be linked to feed conversion efficiency. Similarly one marker each was identified to be linked to growth rate (Ip607) and disease resistance to ESC (Ip477). Ip607 marker linked to both growth rate and feed conversion efficiency, indicating that the QTL for both growth rate and feed conversion efficiency may either be the same or located in the same chromosomal region in the catfish genome. On phenotypic evaluation, certain traits such as growth rate can be accurately evaluated by body weight evaluation while other traits such as disease resistance can be quite complex. The linked DNA markers will be highly useful for MAS programs and for directing further efforts of genomic mapping for important quantitative traits.

• Proceedings of the Korea Port Economic Association Conference
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• 2006.08a
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• pp.253-276
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• 2006

This paper has shown the trend of competition positioning of 26 Korean ports in 1994, 1999, and 2003 by using BCG matrix which consists of relative market shares, growth rate of cargo handling, and also growth rate and CCR and BCC efficiency scores with scale efficiency scores in the vertical and horizontal axes. The empirical main results are as follows. First, Incheon Port, Pyungtag Port, Gwangyang Port, Busan Port, Pohang Port and Woolsan Port have shown their competitive positioning in terms of market share and growth rate. Second, Pyungtag Port, Wando Port, Tongyoung Port, Gohyun Port, Samcheog Port, and Okgae Port have their competitive positioning in terms of growth rate and scale efficiency scores. The main policy implication of this paper is to emphasize that BCG matrix method using in this paper can give seaport manager the basic information for planning the future port management for enhancing the competitive positioning among Korean seaports.

• Korea journal of population studies
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• v.11 no.1
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• pp.32-49
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• 1988

The social conditions in Koreas until 1950s were similar to the model phenomena of low level eqilibrium trap which was named by Prof. Nelson, with the continuation of high population growth rate and low economic growth rate. To escape from the trap, Korean government adopted two different policies, one is economic development plans and the other is family planning programs. Theses policies were successful in both increasing the national products and decreasing the population growth rate. In 1985 per capita GNP increased to over two thousand dollars, fertility rate reduced to replacement level(2.1) and unemployment rate was stabilized at 4 percent level. From various prospects, we were successfully escaped from the Malthusian trap and many economists, who studied developed countries, belive that population growth has positive effects on technological progress, economies of scale, specialization, individual attitude on work, and economic growth. Therefore we need to reexamine the anti-natalistic population policy of Korea in this situation.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.409-413
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• 2005

A method to estimate the autotrophic maximum specific growth rate is presented in this paper. First of all, the concentration of nitrifier is simulated based on the amount of N nitrified, the sludge age and the default value for the decay coefficient. Secondly the OUR of the sludge with access of ammonia is measured. The maximum specific growth rate can be calculated as ${\mu}_{max,A}\;=\;OUR_{max,A}/Y_A$. It was demonstrated that the maximum specific growth rate of autotrophic biomass is not a constants but a time variable parameter. It is concluded that using $OUR_{max,A}$ for dynamic estimating maximum specific growth rate is a good approach and that using a constant value for the maximum specific growth rate over a longer period of time could not predict the performance of activated sludge plants.

• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.837-842
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• 2007

This study was conducted to test the effect of residual Al on plankton community after dissolved air flotation (DAF) application. Growth rate of phytoplankton after DAF application ($0.37day^{-1}$) was about 2 times lower than that before DAF application ($0.70day^{-1}$). Under the condition of addition of nitrogen and phosphorus without light, growth rate phytoplankton in treatment without residual Al increased in difference with showing the negative growth rate in treatment with residual Al. Under the condition of light without addition of nutrient, growth rate of phytoplankton was no noticeable difference between the before and after DAF application. The relatively high settling rate (0.47 m/day) was observed in treatment after DAF application. Although the abundance of rotifer decreased, the abundance of copepod and cladoceran such as Daphnia galeata, Diaphanosoma sp. and Bosmina longirostris with relative higher grazing was no noticeable difference between the before and after DAF application. In the treatments before and after DAF application with zooplankton, growth rate of phytoplankton was $0.41{\pm}0.08day^{-1}$, $0.20{\pm}0.03day^{-1}$, respectively. This difference was in treatment after DAF application similar with those in treatments before and after DAF application without zooplankton. Those indicate that the filter-feeding effect of zooplankton on phytoplankton community may be not changed by residual Al after the DAF application. These results suggest that residual Al after DAF application be to improve water quality by inhibition of growth rate as well as increasing settling rate of phytoplankton.

• ALGAE
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• v.26 no.1
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• pp.73-77
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• 2011

A dominant planktonic bloom-forming species, Mallomonas elongata was isolated from a small shallow eutrophic pond. The growth characteristics of this species on variable silicate concentrations and light intensities were investigated in laboratory unialgal cultures. In culture condition of $15^{\circ}C$, the maximum population growth and the highest growth rate of M. elongata occurred at a light intensity of $80\;{\mu}mol\;m^{-2}s^{-1}$, and in culture condition of $18^{\circ}C$, it exhibited the maximum population growth and the highest growth rates at a light intensity of $50\;{\mu}mol\;m^{-2}s^{-1}$. Silicate concentration had no effect on the population growth and growth rate of M. elongata.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.5
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• pp.382-385
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• 2000

A mathematical model was developed, based on the time dependent changes of the specific growth rate, for prediction of the typical microbial cell growth in batch cultures. This model could predict both the lag growth phase and the stationary growth phase of batch cultures, and it was tested with the batch growth of Trichoderma reesei and Lactobacillus delbrueckii.

• The Korean Journal of Ecology
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• v.21 no.4
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• pp.329-335
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• 1998

The growth of Phytolacca L. grown under three light regimes at three nutrient concentrations was analyzed. The effect of shading treatment on plnat growth was greater than that of nutrient treatment. Plant dry mass increased more than 5-fold during 21 days under 33% and 100% irradiances, whereas that was strongly reduced under 8% irradiance. Net assimilation rate decreased with plant growth irrespective of light and nutrient treatments, though the highest net assimilation rate was shown under 100% irradiance. Under 33% irradiance leaf area in plants supplied with nutrient solution increased to such extent as to compensate reduction in net assimilation rate, whic maintains almost identical growth rate with that under 100% irradiance. The relatonship between total plant nitrogen and leaf nitrogen content was dependent on the growth irradiance. Moreover, leaf nitrogen and specific leaf weight were also changed depending on the light and nutrient conditions. Based on these findings, it is suggested that the adaptive characteristics of Pokeberry plant to light and nutrient conditions may contribute to rapid extension of Pokeberry habital in Korea rocently.

• Transactions of the Korean Society of Mechanical Engineers
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• v.4 no.2
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• pp.47-53
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• 1980

Kikukawa-Compliance method using a conventional clip-on gauge was employed to investigate fatigue crack growth and crack closure in 2017-T3 aluminum alloy. The crack growth rate plot against stress intensity range .DELTA.K on a log-log diagram exhibits a bilinear form with a transition at the growth rate of 10$\^$-4/ mm/cycle. The bilinear form appears still in the plot of growth rate versus effective stress intensity range .DELTA.K$\_$eff/. Fatigue crack growth rate could be well represented by .DELTA.K$\_$eff. The experimental results indicate that the effective stress intensity range ratio U depends on the maximum stress intensity factor K$\_$max/, but the stress ratio R does not affect U. The crack opening stress intensity factor K$\_$op/ tends to increase with increasing K$\_$max/ and decrease with increasing .DELTA.K.