• The Korean Journal of Malacology
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• v.32 no.1
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• pp.25-30
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• 2016

Growth-line analysis was carried out on 80 hard clam (Meretrix petechialis) from the Neolithic Age Eurwang-dong Shell Midden, Incheon, Korea, to determine the seasonality of shellfish collection and site occupation. Growth increments and the marginal index (MI) of the specimens were examined. And then the marginal index was compared to the monthly MI of modern specimens under the assumption that the growth pattern was the same as it is today. MI of the archaeological specimens ranged from 0.12 to 1.55 and was divided into four categories: < 0.63, spring; 0.63-0.76, summer; 0.76-0.89, fall; $${\geq}_-0.89$$, winter collection. As a result, 57 specimens (71.25%) of 80 specimens represented spring, 8 (10.0%) summer, 3 (3.75%) fall and 12 (15.0%) winter collection. The result indicates that shellfish could be collected year-round at the site with an emphasis on spring. Based on the size distribution of shells and the content of the midden, however, it seems that the midden site was not occupied permanently throughout the year but was used repeatedly but temporally for shellfish gathering and processing.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.15 no.4
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• pp.46-54
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• 2019

In this study, the performance of a shell and tube heat exchanger (STHE) and welded plate heat exchanger (WPHE) was measured experimentally. The pass numbers of the STHE was changed by 1, 2 and 4. As a result, the WPHE showed 2.1 times higher heat exchange capacity than that of the STHE. In case of pressure drop, the STHE with 1 and 2 pass number has a lower pressure drop than the WPHE, while the STHE with 4 pass presented higher pressure drop than the WPHE. The performance index considering the heat exchange capacity and pump consumption power, showed in oder of STHE_Pass1 > STHE_Pass2 > W PHE > STHE_Pass4 under the same flow rate. Therefore, when the WPHE was designed optimally under same operating condition with STHE, the maintenance fee and space can be reduced effectively by using the WPHE.

• The Korean Journal of Malacology
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• v.24 no.2
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• pp.97-104
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• 2008

The gonad index, reproductive cycle and first sexual maturity of Sinonovacula constricta collected from Simpo, Kimje-gun, Korea were investigated by histological analysis. The gonad index(GI) in both sexes of S. constricta increased from April and reached a maximum in July when the water temperature rapidly increased. And then, the GI values gradually decreased by spawning from August through October. Monthly variations in the GI showed a close relationship with ovarian development. The reproductive cycle in females and males can be classified into five successive stages: early active stage(March to June), late active stage(May to July), ripe stage(July to September), partially spawned stage(August to October), spent/inactive stage(October to March). The percentage of first sexual maturations in female and male clams of 50.1-60.0 mm in shell length was over 50%, and for clams over 70.1 mm in shell length, it was 100%. Because harvesting clams < 50.1 mm in shell length could potentially cause a drastic reduction in recruitment, a measure including a prohibitory fishing size should be taken for adequate improved fisheries resource management.

• Journal of Environmental Science International
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• v.11 no.7
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• pp.729-735
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• 2002

In order to examine the inhibition effect of other heavy metal ions on the removal of heavy metal ions by crab shell in aqueous solution, 10 heavy metal ions $(Cr^{3+},\;Cd^{2+},\;Ni^{2+},\;Zn^{2+},\;Hg^{2+},\;Cu^{2+},\;Mn^{2+],\;Fe^{2+},\;Fe^{3+},\;Pb^{2+})$ were used as single heavy metal ions and mixed heavy metal ions, respectively. In single heavy metal ions, $Pb^{2+},\;Cr^{3+},\;Cu^{2+}$ were well removed by crab shell, however, $Cd^{2+},\;Ni^{2+},\;Zn^{2+},\;Mn^{2+}$ were not. The heavy metal removal increased as the increase of covalent index (Xm$^2$r), and the relationship classified heavy metal ions as 2 heavy metal groups $(Fe^{3+},\;Fe^{2+},\;Cu^{2+},\; Cr^{3+},\;Mn^{2+},\;Ni^{2+},\;Zn^{2+}\;group\;and\;Pb^{2+},\;Hg^{2+},\;Cd^{2+}\;group)$. In mixed heavy metal ions, the removals of $Fe^{2+},\;Fe^{3+},\;Pb^{2+},\;Cu^{2+}$ as 0.49 m㏖/g, regardless of the existence of other heavy metal ions, were similar to the result of single heavy metal ions experiment. The removals of $Mn^{2+},\;Cd^{2+},\;Ni^{2+}$ decreased as the existence of other heavy metal ions, however, the removal of $Zn^{2+},\;Cr^{3+},\;Hg^{2+}$ increased.

• Development and Reproduction
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• v.25 no.1
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• pp.67-72
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• 2021

This study investigated the IGF-1 signal in specific tissues using Pacific oysters artificially matured via water temperature elevation. Pacific oysters were subjected to water temperature elevation from March to June, and 20 were randomly sampled each month. The condition index (CI) and tissue weight rate (TWR) were examined by measuring shell length, shell height, shell width, and soft tissue weight. The IGF-1 signal in tissues (adductor muscle, digestive glands, gills, labial palps, mantle edges, and gonads) was analyzed by sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. From April to June, the TWR of females and males increased from 19.1±2.9 to 21.0±3.6 and 18.2±2.0 to 19.2±2.5, respectively, while the CI remained the same. The IGF-1 signal in each tissue differed. IGF-1 was expressed in the adductor muscle, while tyrosine was expressed in all tissues. The phosphor (p)-ERK and p-AKT activities were high in the adductor muscle, mantle edge, and gonads. IGF-1 signaling affected the growth and maturity of the Pacific oysters examined.

• Conservation Science in Museum
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• v.27
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• pp.91-102
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• 2022

Silica-based inorganic fillers for restoration of iron objects have been used for the reduction of thermal expansivity and the improvement of melt flow index. However, the higher the amount of filler is applied, the more degradation of mechanical properties and the yellowing occur, which could cause retreatment of the objects with adding stress to them. Thus, research on not only the quantification of a mixture of resin and filler but also the yellowing should be emphasized. Experiments on mechanical properties were carried out with a silica-based light filler, Micro Shell as a comparison group. The results of the experiment showed Micro Shell reduced the number of occurrences of the yellowing by 34% compared to existing fillers. The value of adhesion and specific gravity was also improved depending on the filler amount. The results of this research indicate the possibility of using Micro Shell as a new filler.

• The Korean Journal of Malacology
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• v.19 no.2
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• pp.125-132
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• 2003

Age and growth of the the Jedo venus clam, Protothaca jedoensis were investigated using samples from the subtidal zone of Boryeong, Chungcheongnam- do, Korea from January to December, 1999. The relationship between shell height and ring radius in each group was expressed as a regression line. Therefore, it could be recognized that there is a correspondence in the formation of each ring. Based on the monthly variation of the marginal index of the shell, it was suggested that the annual ring mark formation occurred during the period of February to March once a year. The relationship between shell height (SH) and total weight (TW) was represented by the non-linear equation: TW = 0.0007 SH$^{2.8919}$, and also in the relationship between shell length (SL) and shell height (SH), shell height (SH) and shell width (SW) were represented by the linear equations: SL=1.1067SH+1.778, SW=0.6758SH-0.9824. Growth curves for shell height and total weight fitted to the von Bertalanffy equation were expressed as: SH$_t$ = 81.546(1-e$^{-0.176(t+0.381)}$), TW$_t$ = 227.65(1-e$^{-0.176(t+0.381)})^{2.8919}$.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.513-518
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• 2013

The purpose of vehicle horn sound is for warning to pedestrians. In the past, the main development factor is to match the regulation level. But nowadays perceived quality is more important than level itself. In this study, we measure variety horn sound and evaluate its signals through the jury evaluation aimed at making horn sound quality index. Each contribution of the noise path for sound quality is identified and the target values and methods for implementing the luxurious horn sound are suggested. Finally, we developed, horn component and improve horn mounting condition for luxurious horn sound.

• Smart Structures and Systems
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• v.19 no.1
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• pp.33-38
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• 2017

This research tries to present a nonlinear thermo-elastic solution for a functionally graded spherical shell subjected to mechanical and thermal loads. Geometric nonlinearity is considered using the Lagrange or finite strain tensor. Non-homogeneous material properties are considered based on a power function. Adomian's decomposition method is used for calculation of nonlinear results. Nonlinear results such as displacement can be evaluated for sphere in terms of different indexes of non-homogeneity. A comprehensive comparison between linear and nonlinear results and evaluation of the percentage of difference between them can be performed in this paper. The obtained results indicate that the improvement of the results due to usage of nonlinear analysis is depending on the non-homogeneous index.

• Asian-Australasian Journal of Animal Sciences
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• v.6 no.1
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• pp.1-4
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• 1993

Least square means for egg weight (EW), average shell thickness (ST), shape index (SI), shell surface area (SA) and shell breaking strength (BS) were determined in the Philippine native (PN) and F2 upgrades with New Hampshire (NH-N) and White Leghorn (WL-N) blood, respectively. Eggs of PN were smaller in size but had higher SI while their egg shells were thinner and weaker than those of the two upgrades. Highest EW, SA and BS means were observed in WL-N. Significant (p<0.01) positive correlations of EW and SI with SA and BS were noted.