• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.302-308
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• 1998

The growth of the purple sea urchin, Anthocidaris crassispina, has been investigated using reproduction plates as a chararter of the age determination. The samples were collected on the coast of Daepo, in the southern part of Cheju Island from August, 1995 to July, 1996. Monthly growth of test diameter mainly occurred from December to March. The obvious growth, however, were not observed between April and June which seemed to be the resting period. This resting period well corresponded to the time of annual ring formation which was estimated from the analysis of the marginal growth rate. The growth curve fitted well with Bertalanffy equation: $$L_t=46.65 (1-e^{-0.283(t+9.210)}),\;W_t=44.90 (1-e^{-0.283(t+9.210)})^3$$

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.6
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• pp.695-700
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• 2011

Age, growth, and maturity of Trichiurus lepturus were estimated based on right-handed sagittal otoliths belonging to 1,031 fish collected from January to December 2007 in the East China Sea. The outer margins of the otolith were examined and showed that an opaque zone was formed once per year. Marginal increments in otoliths formed as annual rings between June and August, at the beginning of the spawning season. Fish growth was expressed by the von Bertalanffy growth equation, as follows: $L_t=494.0$ ($1-e^{-0.2453(t+-0.4822)}$) for females and $L_t=330.4$ ($1-e^{-0.4292(t+0.7513)}$) for males, where $L_t$ is the total length in mm and t is age in years. The growth rates of males and females were significantly different (P<0.05).The age composition ranged mostly between ages 2 and 4, and the oldest individuals were 4 years old in males and 6 years old in females. Finally, the age composition of largehead hairtail was compared with data from the 1970s and is discussed in the context of environmental changes.

• Journal of Korean Society of Forest Science
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• v.108 no.3
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• pp.357-363
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• 2019

This study was conducted to develop a stem volume table for Quercus acutissima in Korea by using Kozak's stem taper equation. In total, 2700 tree samples were collected around the country, and growth performance was investigated through compiling data on diameters by stem height and stem analysis. In order to test the stem taper equation's fitness, the fitness index (FI), bias, and mean absolute deviation (MAD) were analyzed. The fitness of the equation was estimated at 97%, bias as 0.017, and MAD turned out to be 1.118, respectively. Furthermore, there was a statistically significant volume difference between the current volume table and the new volume table (p = 0.0008, <0.005). The result indicates that using the new volume table that reflects the actual forest will reduce the loss when assessing wood resources and will improve the accuracy of forest statistics for national and local governments. A stem volume table, the main result of this research, which is utilized in the estimated stem taper equation, will provide growth information for Quercus acutissima, one of the main broadleaf species in Korea, and will function as a management indicator for rational forest management.

• Journal of Welding and Joining
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• v.18 no.6
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• pp.89-95
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• 2000

Creep-fatigue crack growth behavior at the heat affected zone of 1Cr-0.5Mo steel weldment has been experimentally studied. Load hold times of the tests for trapezoidal fatigue waveshapes were varied among 0, 30, 300 and 3,600 seconds. Time-dependent crack growth rates were characterized by the {TEX}$C_{t}${/TEX} estimated with the equation proposed by the previous finite element analysis work. It was concluded that the {TEX}$C_{t}${/TEX} values calculated from the properties of parent metal were quite comparable to the accurate {TEX}$C_{t}${/TEX} values calculated from both of weld and parent metals. Scatter of data was claimed due to the difference of exact location of the cracks in HAZ. The cracks have a tendency to change their path from the original location eventually to the relatively soft HAZ(ie, near-FGHAZ region, fine grained heat affected zone).

• The Korean Journal of Malacology
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• v.17 no.1
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• pp.7-12
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• 2001

The age and growth of the short-necked clam, Paphia undalata, was investigated from 546 samples randomly collected in December 2000 in Kwangyang Bay, Korea. Ages were determined from ring radius of shell and the maximum age was observed to be 2 years. The relationship between shell length (SL) and shell height (SH) of Paphia undalata was SL = 0.2105 ＋ 1.7569 $\times$ SH ($R^2$= 0.98), and the shell length (SL)-total weight (TW) relationship was TW = 2.5824 $\times$ 10$^{-4}$ $\times$ S $L^{2.6769}$ ($R^2$= 0.92). The von Bertalanffy growth parameters were estimated by the non-linear method, with values as follows: $L_{\infty}$ = 81.46 mm, K : 0.20/year, $t_{0}$ = -1.19 year. The von Bertalnanffy growth equation was $L_{t}$ = 81.46(1- $e^{-0}$.20(t+1.19)/), $W_{t}$ = 33.68(1- $e^{-0}$.20(t+1.19)/)$^{2.6769}$.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.592-599
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• 2015

To investigate the characteristic of age and growth, samples of Megangulus venulosus were collected monthly by dredge in the coastal waters of Gangneung, Korea from January to December 2014. The age of M. venulosus was estimated by measuring the ring radius on the shell. Because the relationship between shell lengths and ring radii in each ring group was regressed well, each ring was considered as an annual growth ring. Based on the monthly variation of the marginal index (MI) of the shell length, it is assumed that the ring of this species was formed once a year during September and November. From the parameters calculated using the average length when the year ring was formed, the estimated von Bertalanffy growth equation were $SL_t=236.3(1-e^{-0.061(t+0.184)})$ in age.

• Journal of Korean Society of Forest Science
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• v.21 no.1
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• pp.39-45
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• 1974

The objects of this study are to induce the experimental equation suitable to estimate the height growing process, and to get some information that could be to reduce the error percent on determining the site index. The height growing process per sample plot were made up from the height age curve getted through the stem-analysis of the dominant tree. The 11 equations were calculated in the functional formulas between the age and the dominant height of Alnus hirsuta, Larix leptolepsis, L. Gmelini, P. koraiensis, Abies holophylla, P. rigida, Q. acutissima and Q. aliena. The suitable equation for estimating the guide curve were selected with the highest correlation and the low standard error with comparision on the age-height distributed map as Fig. 2. The suitable equation is different between the species as their calculated results as follows; The growing process of tree height are occasionally found to be polymorphous in the growth pattern as Fig. 3. By this result, the site index are practically found to be always not constant but shows variation to age in same plot as example 5. So, that the site index are estimated from the height-growth curve to age drawing by the stem-analysis or the polymorphic-curve, are concluded to be suitable on the study of site evaluation.

• Knowledge Management Research
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• v.20 no.3
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• pp.1-16
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• 2019

Jobless Growth, one of the most issue keywords for Korea's economy at this moment, stands for an economic situation where the unemployment rate once edging up at the downturn does not fall sharply even after a business cycle is on the stage of its recovery. A remarkable progress of ICT has intensified the apprehension of technology displacing human labor. A remarkable progress of ICT has intensified the apprehension of technology displacing human labor historically. Nowadays, ICT as the main cause for recent jobless growth in Korea ends up with pointing out. This study is to investigate whether the ICT leads to an economic situation of jobless growth. We served an empirical analysis using firm-level panel data from 2009 to 2013 and estimated the effects of ICT on both firm's employment and productivity. A result suggests not only does the employment increase with the rise of ICT investment, but also the employment becomes a complete mediator in terms of linking ICT and firm's productivity. It turns out to be a groundless fear that the ICT rules out human labor causing jobless growth for Korea's economy according to the result revealed.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.8
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• pp.13-19
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• 2021

To provide empirical evidence on the impact of export instability on economic growth in developing countries, this study estimated the neoclassical production function using data of the Jordanian economy for the period 1995-2019. Real exports, real capital, and export instability were the independent variables in the production function. To determine the appropriate methodology for estimating the production function, the study conducted some preliminary tests, including the Augmented-Dickey Fuller (ADF), on the study data. The results of this test indicated that all study variables were stationary at first difference. Therefore, the Johanson cointegration test was applied to determine that there was cointegration between the study variables since the results of the former test indicated that there was one cointegration vector between these variables. The cointegration equation revealed a positive and statistically significant impact of real capital, real exports, and an indicator of export instability on economic growth. The most important policy implications for these results would be reducing the geographical concentration of exports through the expansion of free trade agreements (FTA) to enhance the positive impact of the instability of exports on economic growth. Moreover, the study recommends strengthening export-oriented actions to achieve higher levels of economic growth.

• The Korean Journal of Malacology
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• v.28 no.2
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• pp.109-116
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• 2012

In order to understand the effect of introduction of oyster rack culture on natural short-necked clam, Ruditapes philippinarum, stock, we investigated the status of natural clam stock prior to introduction of oyster rack culture at Yeongheung Coast of Wando Island. The growth equation of the clam was estimated as: $L_t=61.46{\cdot}(1-e^{-0.172(t+0.155)})$ from ring radius composition of shell. Instantaneous coefficient of total mortality and natural mortality were calculated as: 2.4087/year and 0.478/year, respectively. The age at first capture was estimated to be 2.55 year. The total biomass was estimated to 3.23 ton in the bed (0.8 ha). Applied by these parameters, the annual recruit biomass and the current yield per recruit (Y/R) was corresponded to $114.7individuals/m^2$ and $92.0g/m^2$, respectively. Maximum sustainable yield (MSY) was estimated 0.77 ton/year which was close to annual catches, 0.74 ton/year, in the area.