• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.9
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• pp.1722-1727
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• 1992

In this study, techniques of adaptive input-output linearizing control of a class of uncertain nonlinear system are investigated. It is shown through concepts of signal growth rates that bounded trackings yield by adaptive input-output linearizing control law using normalized estimator. The convergence characteristics are improved significantly by using the normalized estimator. Simple example is presented as illustration.

• Journal of Korean Neurosurgical Society
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• v.39 no.3
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• pp.198-203
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• 2006

Objective : To evaluate the natural histories and growth rates of meningiomas, the authors perform this retrospective observational study and attempt to identify those factors predicting tumor growth. Methods : Between 1993 and 2004, a total of 83 patients were diagnosed by computed tomography[CT] scans or magnetic resonance[MR] imaging as having an intracranial meningioma, and were treated by observation only using regular clinical and radiological examinations. Twenty-six of these 83 patients, with available data were included in this study. Follow up periods ranged from 9 to 137 months [mean, 55.6 mo.; median, 60 mo.]. The tumor volumes, absolute growth rates, and tumor doubling times were calculated. Results : Patient age and sex distributions were comparable to those of other studies, but exceptionally 16 meningiomas [62%] were located at the skull base in the present study. During follow-up monitoring, the majority of meningiomas grew, though 77% showed low absolute annual growth rates [$<1cm^3/yr$]. The tumor doubling times ranged from 2.87 to 201.72 years [mean, 42.91 yr]. Based on Imaging analysis, peritumoral edema and the absence of calcification were probable factors predicting tumor growth. Tumor-related symptoms seemed to be slightly related to tumor growth. Other factors, e.g., gender, age, tumor location, and T2-weighted signal Intensities on MR imaging, were not significantly related to tumor growth. Conclusion : This study shows that the majority of meningiomas are slow growing. However, variations in tumor growth are unexplained, thus individualized optimal treatment strategies should be provided in each meningioma.

• ALGAE
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• v.35 no.3
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• pp.263-275
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• 2020

Water temperature is known to affect the growth and feeding of marine dinoflagellates. Each dinoflagellate species grows well at a certain optimal temperature but dies at very cold and hot temperatures. Thus, changes in water temperatures driven by global warming and extremely high or low temperatures can affect the distribution of dinoflagellates. Yihiella yeosuensis is a mixotrophic dinoflagellate that can feed on only the cryptophyte Teleaulax amphioxeia and the chlorophyte Pyramimonas sp. Furthermore, it grows fast mixotrophically but rarely grows photosynthetically. We explored the direct and indirect effects of water temperature on the growth and ingestion rates of Y. yeosuensis feeding on T. amphioxeia and the growth rates of T. amphioxeia and Pyramimonas sp. under 7 different water temperatures (5-35℃). Both the autotrophic and mixotrophic growth rates of Y. yeosuensis on T. amphioxeia were significantly affected by temperature. Under the mixotrophic and autotrophic conditions, Y. yeosuensis survived at 10-25℃, but died at 5℃ and ≥30℃. The maximum mixotrophic growth rate of Y. yeosuensis on T. amphioxeia (1.16 d^-1) was achieved at 25℃, whereas the maximum autotrophic growth rate (0.16 d^-1) was achieved at 15℃. The maximum ingestion rate of Y. yeosuensis on T. amphioxeia (0.24 ng C predator^-1 d^-1) was achieved at 25℃. The cells of T. amphioxeia survived at 10-25℃, but died at 5 and ≥30℃. The cells of Pyramimonas sp. survived at 5-25℃, but died at 30℃. The maximum growth rate of T. amphioxeia (0.72 d^-1) and Pyramimonas sp. (0.75 d^-1) was achieved at 25℃. The abundance of Y. yeosuensis is expected to be high at 25℃, at which its two prey species have their highest growth rates, whereas Y. yeosuensis is expected to be rare or absent at 5℃ or ≥30℃ at which its two prey species do not survive or grow. Therefore, temperature can directly or indirectly affect the population dynamics and distribution of Y. yeosuensis.

• Korean Journal of Environmental Biology
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• v.30 no.1
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• pp.1-8
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• 2012

To understand growth characteristics of eight dominant red tide species ($Prorocentrum$ $minimum$, $Heterocapsa$ $triquetra$, $Scrippsiella$ $trochoidea$, $Akashiwo$ $sanguinea$, $Chattonella$ $marina$, $Heterosigma$ $akashiwo$, $Amphidinium$ $carterae$ and $Rhodomonas$ $salina$) in the Korean coastal water, the growth rates were examined in relation with the impacts of water temperature and bio-volume. Of these, $P.$ $minimum$, $C.$ $marina$, $H.$ $akashiwo$, $A.$ $carterae$ and $R.$ $salina$ were eurythermal species with relatively high growth rates in a borad ranges (15 to $25^{\circ}C$) of water temperature. On the other hand, the growth rate of $H.$ $triquetra$, $S.$ $trochoidea$ and $A.$ $sanguinea$ were high in relatively mid temperature (optimum: $25^{\circ}C$) condition. In particular, $H.$ $triquetra$ was well adapted in low temperature of 5 to $15^{\circ}C$, implying that the species can survive and grows even at very low temperature. Based on results of our experiment, the growth characterestics of five eurythermal species and three mid temperature species may have dominated in Korean coastal water during summer season and fall season, respectively. Contrastively, the growth characteristics of $H.$ $triquetra$ make a consistently dominant during the cold winter season. In addition, the growth rates of large bio-volume species were lower than those of small bio-volume species, indicates that growth of single cells of several flagellates might be depended on the cells sizes.

• Korean Journal of Environmental Biology
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• v.22 no.1
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• pp.153-158
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• 2004

The juvenile gobiidae, Tridentiger trigonocephatus were reared for 40 days under the salinity ranges between 0 and 33.6$\textperthousand$ to examine the effects of salinity on the survival, growth and oxygen consumption rates of the fish. Survival rates were significantly declined for the fish reared under 3.4$\textperthousand$, and daily growth rates were also reduced below 6.7$\textperthousand$ Body length and weight of gobiids reared below 6.7$\textperthousand$ were smaller than those reared above 13.4$\textperthousand$. Oxygen consumption rates in the salinity conditions $\leq$ 10.1$\textperthousand$ were significantly reduced with decreasing salinity. This study reveled that low salinity reduced survival, growth and oxygen consumption rates of the juvenile gobiids suggesting potential influence on the natural mortality of Tridentiger trigonocephalus in the estuarine areas where experience the extreme salinity fluctuations in Korean waters.

• Economic Analysis
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• v.26 no.1
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• pp.133-166
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• 2020

Since the mid-1990s, Korea has been aging rapidly. At the same time, real interest rates have declined sharply. This paper studies whether population aging has contributed to the real interest rate decrease in Korea. We first present empirical evidence that increases in life expectancy and the old-age-dependency ratio, and a fall in population growth, i.e., the population aging, decrease real interest rates. Then we calibrate a life-cycle model to capture the features of the old-age-dependency ratio and population growth in Korea, and show that population aging accounts for about one third of the fall in real interest rates between 1995 and 2018. Furthermore, according to simulation results, increased life expectancy is more important than decreased population growth in affecting the real interest rate decrease during the period.

• The Korean Journal of Applied Statistics
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• v.23 no.4
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• pp.635-650
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• 2010

We model surrender rates with a few explanatory variables such as the difference between reference marke rates and product crediting rates, the policy age since the contract was issued, unemployment rates, economy growth rates, and seasonal effects using logit function. We investigate the policy holder surrender behaviors of US single premium deferred annuities(SPDA) and Korean interest indexed annuities under extreme financial conditions.

• Korean Journal of Microbiology
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• v.23 no.2
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• pp.101-106
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• 1985

The effects of ethanol on the specific rates of growth and ethanol production were found to be threshold and linear inhibition. The degree of inhibition was more apparent on the specific growth rate while ethanol production was continued even the growth was ceased. The nature of uncoupling between the growth (anabolism) and ethanol production (catabolism) was clearly observed under high concentration of ethanol. The uncoupling indicated that ethanol concentration plays a great role in maintenance energy coefficient.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.2
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• pp.42-48
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• 2006

In order to assess the validity of fatigue crack arrest design charts obtained from our previous numerical approach to fatigue crack arrest condition, an extensive fatigue crack growth/arrest test was performed using CT-type integrally stiffened panels. The results are presented as fatigue crack growth rate and non-dimensional crack length relationship, and these are compared with numerically simulated crack growth rates. The measured values of da/dN at the moment of fatigue crack arrest occurred in stiffened panels are good agreement with those numerically simulated crack growth rates.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.3
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• pp.102-109
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• 2002

The fatigue crack growth under mixed mode condition has been discussed within the scope of linear fracture mechanics such as maximum tangential stress, maximum tangential principal stress and minimum strain energy density. The purpose of this study is to investigate the characteristics of fatigue test crack growth in 304 stainless steel under mixed node. The fatigue test results carried out by using inclined pre-crack specimens was compared to both of the theoretical predictions of the criteria, maximum tangential stress and stain energy density. As difference from theoretical analysis, the transition region from mixed mode to mode I appeared in the fatigue test. There is deep relationship between the angle of slanted pre-crack and transition. Therefore, as applying the different stress intensity factor to each node I+II and mode I, the directions and rates of fatigue crack growth are evaluated more accurately under mixed mode.