• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.600-603
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• 2009

Genetic and phenotypic parameter estimates for measurement traits were obtained from pacific oyster Crassostrea gigas at nine months old. For the growth-related traits among nine months old pacific oyster, heritabilities of shell length, shell height, shell width, total weight, body weight and shell weight were estimated as 0.4855, 0.5248, 0.0884, 0.7236, 0.7726 and 0.6957, respectively. Genetic correlations among the growth-related traits of pacific oyster at nines month old, shell length, shell height, shell width, total weight, body weight, shell weight were showing highly positive correlations. Breeding value on growth-related traits of pacific oyster at nine months old were estimated as shell length -7.044-11.870, shell height -11.380-18.370, shell width -1.234-2.831, total weight -8.339-17.140, body weight -1.813-3.507 and shell weight -4.422-8.837. The results show that there is quite substantial additive genetic variance for measurement traits in pacific oyster that can be exploited through selective breeding.

• Korean Journal of Organic Agriculture
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• v.24 no.1
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• pp.115-122
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• 2016

The main purpose of the current study was to compare quality of eggs 1) produced from hens housed in battery cages vs. free range, 2) from young vs. old hens, and 3) tagged with the lowest vs. the highest price in a local franchised mart. The ages of hens, at which their eggs were used for the analysis of quality, were 70 weeks old in the experiment 1, 22 and 47 weeks old in the experiment 2, and were unknown in the experiment 3. Eggs were analyzed for weight, albumen height, Haugh unit, shell color, shell strength, shell thickness, shell weight, yolk color, yolk weight, and egg white weight. In the experiment 1, significant differences were detected between two housing systems in shell color, shell weight, yolk color, and yolk weight (P<0.05), but not in egg weight, albumen height, Haugh unit, shell strength, shell thickness, and egg white weight (P>0.05). Although egg weight was slightly but not significantly higher in battery cages by 2.2 g than in free range, yolk weight was significantly higher in battery cage (P<0.05). On the contrary, shell color was greatly increased in free range system by 68.5% compared with battery cage. In the experiment 2, there were significant differences between young and old hens in egg weight, albumen height, Haugh unit, shell strength, shell weight, yolk color and yolk weight (P<0.05). Egg weight, shell weight, yolk color and yolk weight were increased in old hens than young hens while albumen height, Haugh unit, and shell strength were decreased. In the experiment 3, egg weight, albumen height, Haugh unit, shell weight, and egg white weight were significantly higher in the highest priced eggs than the lowest ones (P<0.05), whereas shell strength and yolk color were lower (P<0.05) but shell color, shell thickness and yolk weight were not different (P>0.05). So, egg freshness was clearly higher in the highest priced ones than in the lowest (P<0.05). Due to the limited information on raising and husbandry of laying hens whose eggs were tested for egg quality in the current study, the present results should be cautiously interpreted while contributing to the future study as a basis in this field.

• The Korean Journal of Malacology
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• v.23 no.2
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• pp.227-233
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• 2007

The amount of Batillus cornutus captured in Jeju Island was about 2,000 tons/year for three years after 2000. The mean size of B. cornutus by shell height was 7.7 cm in 2001, 7.9 cm in 2002, and 8.1 cm in 2003. Local mean size of B. cornutus by shell height was 8.7 cm in eastern waters, 7.4 cm in western waters, 7.8 cm in southern waters, and 7.7 cm in northern waters of Jeju Island. To investigate the effect of the growth pattern, an experiment was conducted: the samples were tagged and released in southern coastal waters of Jeju Island on 2nd April (a release test) and 29th October (a recapture test) in 2003. The release stations were two sites, natural reef and artificial reef, where their environmental conditions were different from each other. In April, the size of B. cornutus released in the natural reef was 6.2 cm in mean shell height, and 58.9 g in mean shell weight. The size of B. cornutus released in the artificial reef was 6.6 cm in mean shell height, and 65.9 g in mean shell weight. During the release period, most of B. cornutus were not moved much (less than 10 m) from the original release sites. When B. cornutus was recaptured in October after 7 months, the size of B. cornutus released in the natural reef became 7.4 cm in mean shell height, and 89.4 g in mean shell weight. The size of B. cornutus released in the artificial reef became 7.2 cm in mean shell height, and 84.9 g in mean shell weight. This indicates that the growth rate of B. cornutus released in the natural reef was higher than that of B. cornutus in the artificial reef. These differences in the growth of B. cornutus between study sites were ascribed to the abundance of marine algae grazed by immobile B. cornutus. Namely, with relatively high growth rate of B. cornutus in the natural reef, the number of species (23 species) and biomass (26,703.4 g) of algae were more diverse and abundant than those (7 species and 17,018.4 g) of algae in the artificial reef. The growth of B. cornutus in the natural reef was also correlated to high water temperature $(15.5-25.9^{\circ}C)$.

• Advances in concrete construction
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• v.13 no.3
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• pp.223-231
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• 2022

The problem is formulated by applying the Kirchhoff's conception for shell theory. The longitudinal modal displacement functions are assessed by characteristic beam ones meet clamped-clamped end conditions applied at the shell edges. The fundamental natural frequency of rotating functionally graded cylindrical shells of different parameter versus ratios of length-to-diameter and height-to-diameter for a wide range has been reported and investigated through the study with fractions laws. The frequency first increases and gain maximum value with the increase of circumferential wave mode. By increasing different value of height-to-radius ratio, the resulting backward and forward frequencies increase and frequencies decrease on increasing height-to-radius ratio. Moreover, on increasing the rotating speed, the backward frequencies increases and forward frequencies decreases. The trigonometric frequencies are lower than that of exponential and polynomial frequencies. Stability of a cylindrical shell depends highly on these aspects of material. More the shell material sustains a load due to physical situations, the more the shell is stable. Any predicted fatigue due to burden of vibrations is evaded by estimating their dynamical aspects.

• The Korean Journal of Malacology
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• v.29 no.1
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• pp.43-50
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• 2013

We investigated the growth performance of oysters (initial shell height $57.5{\pm}8.5$ mm) under differing conditions of tidal exposure time and culture rack height in an experiment that commenced in April, 2011. Significant differences were observed in shell height from June 2011, in total weight from August, and in meat weight from September. Fatness tended to decrease during the experimental period, but was not significantly different at the end of the experiment. Significant differences in survival rates were mainly observed from June to August. After September, further changes were not observed in any experimental treatment group. The greatest growth potential ($L_{\infty}$) and survival rate were observed at a sea level of approximately 116 cm. The results indicate that in the study area the use of oyster culture conditions involving 1 or 2 h of tidal exposure and 60 - 70 cm rack height could result in oysters reaching the favored commercial half shell size within 14 months, with > 80% survival.

• Korean Journal of Poultry Science
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• v.43 no.1
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• pp.31-38
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• 2016

Consumers demand fresh and high-quality eggs. Egg quality may be represented by shell color, shell weight, egg weight, shell thickness, shell density, albumen height, yolk color, albumen pH and viscosity. Various factors such as strain, age of hen, storage temperature, humidity, the presence of $CO_2$ and storage time affect egg quality. Therefore, we investigated the effects of storage time and temperature on egg quality to define the freshness of Korean market eggs. A total of 1,800 eggs were used for this experiment and were separated into 45 treatments with 40 eggs in each. The treatments were consisted of 15 storage periods (2 d to 30 d) and 3 storage temperatures ($2^{\circ}C$, $12^{\circ}C$, $25^{\circ}C$). Each egg was weighed and broken, and the height of the thick albumen, Haugh units (HU), egg shell color and yolk color were measured by a QCM+system. We also observed the physiochemical properties of eggs such as yolk pH, albumen pH and albumen viscosity. The egg weight, shell weight, albumen height, HU and albumen viscosity significantly decreased with increasing storage time and temperature. However, the albumen and yolk pH significantly increased with increasing storage period and temperature. The interaction effects between the storage period and temperature were significant for shell weight, shell density, egg weight, albumen height, HU, yolk color, yolk pH, albumen pH and albumen viscosity. In the analysis of the correlation with egg quality, the storage temperature exhibited a higher correlation coefficient than the storage period. In conclusion, storage time and temperature are the major factors affecting egg quality, but the storage temperature is a more sensitive determinant of egg quality deterioration compared with the storage period.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.4
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• pp.152-157
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• 2006

Samples of Meretrix lusoria were collected monthly from the tidal flat of Simpo, Puan-gun, Chollabuk-do, west coast of Korea from April 2004 to March 2005. Age of M. lusoria was determined from the rings on the shell. The relationship between shell length and ring radius in each ring group was expressed as a regression line. Therefore, there is a correspondence in each ring formation. Based on the monthly variations in the marginal index (MI') of the shell, it is assumed that the ring of this species was formed once a year during the period of February to April. The relationship between shell length (SL) and shell height (SH; mm) was highly correlated with shell height as the following equation: SH = 0.8103 SL + 0.5145 $(r^2=0.991)$. The shell length (SL) - shell width (SW) relation was also expressed by the following equation: SW = 0.4897 SL + 0.0315 $(r^2=0.976)$. Shell length (SL; mm) and total weight (TW; g) was expressed by the following equation: $TW=2.9195\times10^{-4}\;SL^{2.9547}\;(R^2=0.991)$. Shell length (SL) and shell height (SH; mm) was highly correlated with shell height as the following equation: $SH=0.8103\;SL+0.5145\;(R^2=0.991)$ The shell length (SL) - shell width (SW) relation was also expressed by the following equation: $SW=0.4897\;SL+0.0315\;(R^2=0.976)$. Growth curves for shell length and total weight fitted to the von Bertalanffy's growth curve were expressed respectively as: $SL_t=104.9[l-e^{-0.2235(t+0.7677)}],\;TW_t=280.8[l-e^{-0.2235(t+0.7677)}]^{2.9547}$.

• Computers and Concrete
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• v.25 no.5
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• pp.411-425
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• 2020

In this paper, the shell material has been taken as functionally graded material and their material quantity is located by the exponential volume fraction law. Moreover, the impact of ring supports around the shell circumference has been examined for their various positions along the shell axial length. These rings support restraints the radial displacement in the transverse direction. While the axial modal deformation functions have been estimated by characteristic beam functions and nature of materials used for construction of cylindrical shells. The fundamental natural frequency of cylindrical shell of parameter versus ratios of length- and height-to-radius for a wide range has been reported and investigated through the study. In addition, by increasing height-to-radius ratio resulting frequencies also increase and frequencies decrease on ratio of length-to-radius. Though the trends of frequency values of both ratios are converse to each other with three different boundary conditions. Also it is examined the position of ring supports with length-to radius ratio, height-to-radius ratio and varying the exponent of volume fraction. MATLAB software package has been utilized for extracting shell frequency spectra. The obtained results are confirmed by comparing with available literature.

• The Korean Journal of Malacology
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• v.1 no.1
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• pp.13-18
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• 1985

The metamorphosis and the growth of larva in Limnoperna fortunei were studied from October, 1981 to December, 1983. 1) The larva of this species is observed in the three different stages in the form of D-shaped. The shell length of the larva in the early stage is $130.44{\mu}m$ to $143.60{\mu}m$ and in the middle stage $161.67{\mu}m$ to $184.11{\mu}m$. In the late stage the length size of the larva increases up to $194.55{\mu}m$ to $208.45{\mu}m$. The shell height is $103.19{\mu}m$, to $119.47{\mu}m$, $126.51{\mu}m$ to $157.63{\mu}m$ and $136.87{\mu}m$ to $176.35{\mu}m$ in the three stages respectively. Thus the growth ratio of shell length to shell height is 1:0.75. 2) The metamorphosing stage begins when the shell height becomes larger than $210{\mu}m$ and the shell length exceedes $260{\mu}m$.

• Journal of Aquaculture
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• v.10 no.2
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• pp.97-103
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• 1997

Larval growth of the oyster, Crassostrea nippona, was investigated at the different conditions such as water volume, depth of culture vessel and initiative feeding time at $23^{\circ}C$. As a result, morphological changes were occurred during the early larval growth. That is, shell length was higher than shell height at the time of D-shaped larvae. Later, the length became equal to the hight when their shell length reached $127\mum$and then shell height increased rapidly. Some of pediveliger larvae with the size of $360\mum\;in\;shell\;length\;and\;385\mum$ in shell height began to temporarily settle on the substrate after 18 days. The result also indicated that the depth of culture vessel turned out to be an important factor rather than water volume for the larval growth. The fist feeding time of oyster larvae appeared to be the first day after fertilization.