• Fisheries and Aquatic Sciences
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• v.9 no.4
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• pp.153-159
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• 2006

The ark shell (or 'blood clam') Scapharca broughtonii is a filter-feeding bivalve that has red blood and inhabits waters approximately 10m in depth off the southern coast of South Korea. This study was part of a larger research project investigating the causes of death and restoration of shellfish resources, which are important aquaculture products in South Korea. We examined physiological responses related to survival, respiration, excretion, and amino acid changes as a result of changes in salinity. The 9-day median lethal salinity ($LS_{50}$) was 16.5 psu with confidence limits of 14.9-18.1 psu. At $25^{\circ}C$, the oxygen consumption and ammonia-nitrogen excretion rates were increased with decreases in salinity. Although the osmolality of individuals was acclimated within 2 h at 26.4 psu and 12 h at 19.8 psu, it took more than 5 days at a salinity of 13.2 psu, whereas no individuals acclimated and all died at a salinity of 6.6 psu. Of the amino acids present in the blood, taurine and alanine increased in response to decreased salinity. Tissues of the gill and the mid-gut gland were affected by decreasing salinity. These data will provide important fundamental information for examining the causes of mass mortality of shellfish in the summer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.5
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• pp.556-565
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• 2018

The age and growth of butter clams Saxidomus purpuratus were estimated using transmitted light on the shells of 364 samples from January 2017 to December 2017 in Jinhae Bay. Based on monthly variation in the marginal index (MI) of the shell, it is assumed that rings are formed once a year during the period from July to August in this species. The relationship between shell length (SL; mm) and shell height (SH; mm) was expressed by the equation SH=0.8053SL-2.9636 ($R^2=0.94$) and between SL and shell width (SW; mm) by the equation SW=0.5648SL-3.7105 ($R^2=0.90$). The relationship between SL and total weight (TW; g) was expressed by the following equation: $TW=0.00009SL^{3.2141}$ ($R^2=0.96$). von Bertalanffy's growth parameters were estimated using the regression wizard in the SigmaPlot computer program (Systat Software, Inc., v. 10.0). The maximum shell length ($SL_{\infty}$) was 126.16 mm, growth rate was 0.2030/year, theoretical age at shell length 0 ($t_0$) was -0.52 years, and asymptotic total weight ($TW_{\infty}$) was 509.17 g. Growth curves for SL and TW fitted to the von Bertalanffy's equation were expressed as follows: $SL_t=126.16(1-e^{-0.2030(t+0.52)})$, $TW_t=509.17(1-e^{-0.2030(t+0.52)})^{3.2141}$.

• Journal of Life Science
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• v.17 no.1 s.81
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• pp.162-165
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• 2007

Brown Ring Disease (BRD) is a bacterial disease caused by Vibrio tapetis which affects cultured clam Ruditapes philippinarum and causes heavy economic losses on Atlantic coasts of france, Spain and England. In this study, to evaluate the effective detection of the pathogen, specific primer set based on 16S ribosomal RNA (rRNA) sequences designed for rapid detection of V. tapetis. Polymerase chain reaction (PCR) with this primer set produced the specific band for each V. tapetis. The length of PCR product using designed primer set of Vbts-F and Vbts-R was about 400 bp. Therefore, these primers will be provided with a basic tool for rapid detection of V. tapetis in the various cases such as examination of imported aquatic products, diagnosis of aquatic organisms, and etc.

• Journal of the Korean Applied Science and Technology
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• v.10 no.2
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• pp.11-18
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• 1993

Contents of vitamin $D_3$ and 25-OH-vitamin $D_3$ in marine animal products(20 species) were determined by HPLC. The isomers of vitamin D, $D_2$ and $D_3$, were not clearly separated on a reversed phase, ${\mu}$ Bonda Pak, with 20% methanol-acetonitrile, and on a normal phase, Zorbax SIL. with 0.4% isopropanol-hexane, but 25-OH-vitamin $D_2$ and-$D_3$ were separated on either ${\mu}$ Bonda Pak with 10% methanol-acetonitrile, or on Zorbax SIL with 2.2% isopropanol-hexane, respectively. Although levels of vitamin $D_3$ and 25-OH-vitamin $D_3$ varied remarkably according to species, their average value(fish : $l,l87{sim}36,007$ I.U/sample 100g, mussel : $58{\sim}1,706$ I.U/sample 100g, pickle: $1,208{\sim}79,358$ I.U/sample 100g) was greatly higher than that of meat($80{\sim}100$ I.U/sample 100g) and dairy products($400{\sim}800$ I.U/sample 100g). Fatty tissues of fish and pickled fish intestines contained high level of vitamin $D_3$ and 25-OH-vitamin $D_3$, while the clam and mussel known to have various kinds of sterol including ${\Delta}^7$-sterol showed very low levels of vitamin $D_3$ and its derivative.

• Journal of the Korean Chemical Society
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• v.6 no.1
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• pp.25-28
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• 1962

The colorimetric estimation, by dithiol method, of the solubility of tin dissolved from the container the tin plate in some canned marine foods has been made on 200 cans of sample on the market. Some of them contained more than 150 ppm of Sn concentration were as follows; (1) ca. 50% of squid can, (2)ca. 30% of mackerel can, (3) ca. of saury can, (4) naught of crab, whale, clam(Japanese hard clams), fish meat ball, and Turbo cornutus one. (1) It had the tendency of increasing Sn concentration according to lowering or arising the value of pH. (2) No significant difference in Sn concentration was caused by the variation of the sort of tinning as H-D or E-T. (3) The longer the period of the storage the higher Sn concentration was found, and the concentration more than 150 ppm of Sn was generally found among the cans stored more than twelve months. (4) The concentration of Sn in the liquid was higher than in solid portion, and most of dissolved Sn was distributed in the liquid portion.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.5
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• pp.552-557
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• 2014

The objective of the This study is to access the speed performance employing the sea trial test and CFD with the our own designed and manufactured one-man boat. The overall design process including hull form design was explained. The sea trial was carried out with a manufactured boat in the clam sea. Brake power at the design speed of a boat through the sea trial was measured as 1680 W. The flow computation was conducted considering free surface and dynamic trim using a commercial CFD code(STAR-CCM+). The result of computation provided the information that residual resistance is bigger than fraction's at design speed. The total efficiency were predicted based on the sea trial and CFD. The Total efficiency was divided into shaft efficiency and quasi-propulsive efficiency. By using quasi-propulsive efficiency, it becomes possible to predict speed performance of boat in future. The results can provide information regarding hull form design, performance analysis and development of a boat in future.

• Korean Journal of Food Science and Technology
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• v.44 no.4
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• pp.390-392
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• 2012

Diarrhetic shellfish poisoning toxins were investigated by liquid chromatography-electrospray ionization mass spectrometry (LC-MS/MS). Okadaic acid (OA), Dinophysistoxin-1 (DTX1), Pectonotoxin2, (PTX2) and Yessotoxin (YTX) in bivalves were quantified. OA were found in four samples; mussel Mytilus edulis (0.001 ${\mu}g/g$), Oyster Crassostrea gigas (0.004 and 0.001 ${\mu}g/g$) and manila clam Ruditapes philippinarum (0.001 ${\mu}g/g$). DTX1, PTX2, and YTX were not detected from all of the samples examined.

• The Korean Journal of Malacology
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• v.26 no.3
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• pp.211-215
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• 2010

The genus Perkinsus are parasitic protozoans that cause massive inflammatory responses in infected marine shellfish worldwide. This ultimately leads to great economic losses. This study examined the effects of water temperature and salinity on the formation of prezoosporangia and zoosporangia in order to understand the ecology of the pathogens. The induction of prezoosporangia from trophozoites occurred readily at higher water temperatures (20 and $30^{\circ}C$) and they had larger diameters than those incubated at lower temperatures (4 and $10^{\circ}C$). The formation of zoospores in prezoosporangia was also strongly influenced by water temperature and salinity; prezoosporangia exposed to water temperatures of 20 and $30^{\circ}C$ and salinities of 20 and 30 ppt had high rates of zoosporulation, while no or very low rates of zoosporulation were observed at temperatures below $10^{\circ}C$ or salinity below 10 ppt. Our data will be useful for the development of strategies to counter P. olseni proliferation in Korean waters.

• The Journal of Korean Physical Therapy
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• v.31 no.1
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• pp.62-66
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• 2019

Purpose: This study examined the most efficient exercise position to activate the gluteus medius (GM) and tensor fascia latae (TFL) in hip abduction in side-lying (HA-SL), clam in side-lying (CL-SL), and sling bridging in side-lying (SB-SL), which are the most representative GM exercises. Methods: Twenty-four healthy male adults aged from 20 to 40 years, whose body mass index was under 25, participated in this experiment. While all participants conducted three different positions with a counterbalanced manner, such as in AB, CL, and BR, activation of the GM and TFL was measured using 8-channel wireless EMG. Exercise was performed for 10 seconds three times in total with a five minute-break session. Results: Significant differences in GM and TFL activation were observed among the three positions (p<0.05). The highest activation of 60.69 was observed in BR followed in order by 46.03 and 12.92 in HA-SL and CL, respectively. TFL activation in HA-SL was 42.01, followed in order by 35.98 and 14.01 in BR and CL, respectively. On the other hand, there was no significant difference in TFL muscle activation between BR and HA-SL. Conclusion: These findings suggest that both BR and HA-SL in GM can be done selectively. CL has remarkably low muscle activation in GM and TFL, which makes it less valuable in GM and TFL exercise. In conclusion, selective BR and HA-SL exercise should be applied to maximally and effectively activate the GM.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.1
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• pp.55-66
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• 2002

Electronic cash system based on anonymous coins have been invented by David Chaum. However, von Solms and Naccache discovered that such anonymous coins also very well suited to support criminals in Blacoailing. In this paper, we suggest a method that a client informs a bank of the information about blackmailing attack by using Schnorr identification protocol of XTR version at the stage of identification, whenever he is blackmailed. In general, blackmailing is the most serious among the various drawbacks of electronic cash system. Especially, blackmiling to be done when the client is kidnapped brings a fatal result to electronic cash system. But if the Schnorr identification protocol of XTR version is used, we can efficiently defeat blackmailing without assumption required in the existing method to defeat blackmailing.