• The Korean Journal of Malacology
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• v.24 no.3
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• pp.167-173
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• 2008

The survival and growth of Glossaulax didyma didyma ($R{\ddot{o}}ding$) were measured in the laboratory under controlled conditions, such as water temperature, salinity and diet. The effect of temperature on G. didyma didyma was examined at four different levels (15, 20, 25 and $30^{\circ}C$) with 30 psu for 30 days. The results show that the growth and survival rates of G. didyma didyma were significantly higher at $15^{\circ}C$ and $20^{\circ}C$ than at other temperatures. The effect of salinity on G. didyma didyma was also examined at six different levels (10, 15, 20, 25, 30 and 35 psu) in $20^{\circ}C$ for 40 days. The results showed that the growth and survival rates of G. didyma didyma were significantly higher at 30 psu and 35 psu than at other salinities. Finally, the effect of diets on G. didyma didyma was examined with three single-component diets (prawn, shellfish and fish) at $20^{\circ}C$ and 30 psu for 60 days. The results showed that the growth and survival rates of G. didyma didyma fed on shellfish were significantly higher than those fed on prawn and fish.

• Child Health Nursing Research
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• v.29 no.2
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• pp.128-136
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• 2023

Purpose: This study aimed to identify the main keywords and research topics used in research on problematic smartphone use (PSU) among children (6-12 years old), including parental factors. Methods: The publication period for the literature was set from January 2007 to January 2022, as smartphones were first released in 2007. In total, 395 articles were identified, 230 of which were included in the final analysis. Text network analysis was performed using NetMiner 4.5. Results: Research on this topic has steadily increased since 2007, with 40 papers published in 2021. Eight main research topics were derived: group 1, parental attitudes; group 2, children's PSU behavior and parental support; group 3, family environment and behavioral addiction; group 4, social relationships; group 5, seeking solutions; group 6, parent-child relationships; group 7, children's mental health and school adaptation; and group 8, PSU in adolescents. Conclusion: Parental factors related to PSU have been studied in various aspects. However, more active research on school-age children's PSU needs to be conducted due to the paucity of research in this population compared to studies conducted among adolescents. The results of this study provide useful data for selecting research topics in the field of PSU.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.1
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• pp.25-31
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• 2017

The optimum temperature and salinity for long-distance transportation of rockfish Sebastes schlegeli were investigated by assessing hematological characteristics and hemocyte mortality. The possible effects of the interaction of temperature and salinity on these attributes were also investigated. No significant difference was found in hematocrit and hemoglobin among experimental conditions. Glucose levels were highest in fish exposed to salinities of 34 psu ($4^{\circ}C$), 18 psu ($4-6^{\circ}C$) and 10 psu ($4-8^{\circ}C$). Cortisol levels were elevated in the lowest temperature group ($4^{\circ}C$), but upper limits decreased with decreasing salinity. AST and ALT increased as temperature decreased at salinities lower than 26 psu. The ratio of living cells was 99.0-99.6% in all experimental groups. The percentage of necrotic cells was highest in fish exposed to salinities of 34 psu ($4^{\circ}C$), 18 psu ($6-8^{\circ}C$), and 10 psu ($4-8^{\circ}C$). The percentage of necrotic cells decreased significantly as temperature and salinity decreased, indicating that both salinity and the interaction of salinity and temperature affected cell necrosis.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.2
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• pp.526-536
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• 2015

Changes of oxygen consumption in juvenile giant grouper, Epinephelus lanceolatus were investigated in order to find out the physiological responses associated with freshwater and low salinities acclimation. Salinity changes in this experiment were set as follows; 35 psu (Exp. I) as control, decrease in the manners of $35{\rightarrow}20{\rightarrow}10{\rightarrow}0$ psu (Exp. II), $35{\rightarrow}10{\rightarrow}0$ psu (Exp. III) and $35{\rightarrow}0$ psu (Exp. IV). The average oxygen consumption at $27^{\circ}C$ in Exp. I (control) was $106.9{\pm}0.7mg$ $O_2/kg/h$. In Exp. II, according to the changes of $35{\rightarrow}20{\rightarrow}10{\rightarrow}0$ psu in freshwater acclimation, fish showed the gradual decrease in oxygen consumption as $108.1{\pm}2.1$, $99.6{\pm}2.9$, $74.6{\pm}0.9$ and $62.7{\pm}1.0mg$ $O_2/kg/h$, respectively. The fish in Exp. III also revealed the same tendency as $106.5{\pm}1.3$, $77.0{\pm}1.2$ and $64.7{\pm}1.2mg$ $O_2/kg/h$, respectively. In Exp. IV, fish showed the decreased oxygen consumption from $109.0{\pm}0.9mg$ $O_2/kg/h$ of 35 psu to $71.6{\pm}2.0mg$ $O_2/kg/h$ of 0 psu. Giant grouper is thought to be a diurnal fish species, because the level of oxygen consumption during light period was higher than that during dark period.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.3
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• pp.139-148
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• 2012

The short-term variation of salinity and temperature in a dyked estuarine environment is mainly controlled by the freshwater discharge from the dyke. We examined the distribution of salinity and temperature by the freshwater discharge in the Yeongsan River estuary using the CTD data obtained from 8 stations through three surveys in June (weak discharge) and August (intensive discharge), 2010. During the weak discharge in June, the surface salinity showed 30-32.5 psu and its horizontal gradient was relatively high around Goha-do (0.25~0.32 psu/km). On the other hand, the salinity of the bottom layer was almost constant in the range of 33 psu. Water temperature ranged $19{\sim}21^{\circ}C$ and displayed higher gradient in north-south direction than the gradient of east-west direction. During the intensive freshwater discharge on August 12, the salinity dropped to 9~26 psu. The maximum horizontal gradient of surface salinity reached 3.8 psu/km in the north of Goha-do where the strong salinity front was formed, and the horizontal salinity gradient of bottom layer was 0.28 psu/km. The horizontal gradient of water temperature was $-0.45^{\circ}C/km$ in the surface and $-0.12^{\circ}C/km$ in the bottom with high surface temperature near the dyke and decreasing gradually to the river mouth. After 3 days of the intensive discharge ($3^{rd}$ survey), the surface salinity increased to 22~26 psu. However, there still existed relatively high horizontal gradient around Goha-do. In the mean time, the bottom salinity decreased to 26.5~27.5 psu, but its gradient was not big as much as the surface gradient. According to time series of CTD profile near the dyke, the discharged fresh water jetted down temporarily and then recovered gradually with the recovering speed of 0.4 m/hour for the discharge case of $13{\times}10^6$ ton. Due to the combined effects of freshwater discharge and surface heating during the summer of 2010, the Yeongsan estuary, in general, underwent intensified vertical stratification, which in turn caused the inhibition of vertical mixing, especially inside area of estuary. Based on the spatial distribution of salinity and temperature, the Yeongsan estuary can be divided into three regions: the Goha-do area with strong horizontal gradient of salinity and temperature, inner estuary from Goha-do to the dyke with low salinity, and outer estuary from Goha-do to the coasts with relatively high salinity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.1
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• pp.7-12
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• 2004

This study investigated the possibility of salinity acclimation of freshwater rotifers (Brachionus calyciflorus) as live food for sweetfish (Plecoglossus altivelis) larvae, and also examined the optimal salinity for the growth of sweetfish. Freshwater rotifers cultured in 0 and 4 PSU and seawater rotifers (B. rotundiformis) cultured in 33 PSU were supplied to the larvae with four kinds of enrichment material (condensed freshwater Chlorella, $\omega-yeast,$ baker's yeast, Super Selco) and larval growth at 4 PSU was examined. Growth of the freshwater rotifers positively increased from 0 PSU to 6 PSU, but decreased when over 8 PSU was reached. Growth and survival of the sweet fish larvae reared in 0 PSU were significantly lower than those reared in either 4 PSU or 33 PSU. This indicated that the freshwater rotifers (B. calyciflorus) could be used as live food for sweetfish larvae reared in 4 PSU. The body weight of sweetfish larvae fed on freshwater rotifers enriched with Super Selco was the highest at 0.163 mg, but there was no significant difference in survival and body length of the fish fed with the other enrichment materials. The content of n-3 HUFA of the sweetfish larvae fed on the freshwater rotifers enriched with Super Selco and the condensed freshwater Chlorella was higher than that enriched with $\omega-yeast$ and baker's yeast. These results indicated that B. calyciflorus cultured with the condensed freshwater Chlorella could be used for the sweetfish larvae without enrichment, and the most efficient enrichment material for B. calyciflorus is Super Selco.

• Development and Reproduction
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• v.20 no.3
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• pp.187-196
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• 2016

The objective of the current study was to determine acute plasma stress responses in two size groups of juvenile Epinephelus akaara (average body weight: $8.4{\pm}2.1$ and $3.3{\pm}0.6g$; 150 and 120 days after hatch, respectively) exposed to abrupt salinity drops (from 34 practical salinity unit, PSU seawater to 18, 10 PSU (experiment 1) or 26, 18, 10 PSU (experiment 2), respectively). Plasma glucose, glutamic oxalate transaminase, glutamic pyruvate transaminase, red blood cell counts, and gill histology were determined during 72 h exposure. Significantly increased plasma glucose, glutamic oxalate transaminase levels, and red blood cell counts were observed in fish exposed to 18 or 10 PSU. Histological changes, such as hyperplasia and lifting of epithelium in the gill secondary lamellae, were also observed in fish exposed to 18 or 10 PSU at 72 h post-drop. E. akaara exposed to sudden salinity drops to 18 or 10 PSU still seems to undergo the primary adjustment phase before fish reaches a new homeostasis, whereas fish exposed to 26 PSU seems to mount osmotic changes. Therefore, the no observed adverse effect levels for 72 h acute salinity challenge was 26 PSU in our study, and salinity drop to 18 PSU and below can possibly cause acute adverse effect, in which fish could be vulnerable to additional stresses such as a temperature changes or handling stress.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.4
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• pp.211-217
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• 2001

Physical oceanographic environments in the coastal sea of Chung-Moon located in the south coast of Cheju Island, Korea, where water pollutions by growing tourism complex possibly start to influence on the ecological system, are studied with hydrographic data observed monthly during July 1997 to June 2000. Winter and summer characteristics are shown in December to April and June to October, respectively, and transitional characteristics are shown in May and November. Waters show 14{\sim}16^{\circ}C$ and 34${\sim}$34.7 psu in winter and $15{\sim}27^{\circ}C$ and 32${\sim}$34.3 psu in summer. It tells that Tsushima water distributes in the whole column in winter and in the lower layer in summer, and Yangtze coastal water appears in the surface water in summer. When the influence of Yangtze coastal water is strong, salinities below 30psu are shown. Stratification is formed in the depth of about 20 m from June to October, so that it is not shown in the near shore stations, of which the depth is about10 m. Isotherms and isohalines sometimes tend to be perpendicular to the coast line in the surface, which seems to show influences from the steam power plant near St. 1 and the sewage disposal plant near St. 3. During the observation period, temperatures in St. 1 are a little higher than those in St. 2 and St. 3 except for a couple of months in summer and salinities in St. 3 are mostly a little lower than those in St. 1 and St. 2. Their effects seem to be no more than $0.4^{\circ}C$ in a distance of 300 m and no more than 0.1 psu within a distance of 30 m.

• Journal of Aquaculture
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• v.20 no.4
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• pp.226-231
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• 2007

We investigated survival and osmolarity, oxygen consumption, amonia extetion and filtration rates associated with physiological responses of the tunicate Halocynthia roretzi salinity changes. Acclimation times for osmolatity in different salinities took $20{\sim}26$ hours in 60% SW (19.8 psu) and $20{\sim}25$ hours in 80% SW (26.4 psu), while their times took $7{\sim}8$ hours in 110% SW (36.3 psu). Accordingly, acclimation times for high salinities were faster than those for low salinities. Survival (%) was more than 80% at salinity over 26.4 psu, and 6 $days-LS_{50}$ was 25.4 psu. physiological responses such as oxygen consumption, amonia excretion and filtration rates of H. roretzi showed more clear reactions in the longer exposure period (four days after exposure) than that in the beginning of the exposure. To sum up the results, the tunicate might be stressed from the beginning of the exposure in low salinity.

• Journal of Veterinary Science
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• v.25 no.4
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• pp.50.1-50.6
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• 2024

Importance: Canine extraction of large carnivores can pose significant risk due to extensive tissue damage during aggressive bone reduction. This report highlights a rare instance in which the use of a piezoelectric surgical unit (PSU) for maxillary canine extraction in a large carnivore resulted in successful outcomes with minimal tissue damage. Case presentation: A 10-year-old male African lion presented with decreased appetite because of bilateral maxillary canine fractures. Intraoral radiographs revealed enlarged root canals and periapical radiolucency of the fractured canines, leading to a diagnosis of periapical periodontitis and pulpitis. To extract the right maxillary canine, conventional method using hand instrument failed to achieve adequate luxation, necessitating the use of the flat blade of the PSU to sever the periodontal ligament. The left maxillary canine was extracted using PSU from the beginning, and the extraction time was markedly shortened by using PSU without additional alveolar bone damage or bleeding. Conclusion and Relevance: This case demonstrated that utilizing PSU for canine extraction in a lion resulted in periodontal ligament separation, reducing damage to the alveolar bone and shortening surgical time. It suggests the promising application of PSU in tooth extraction for large wild animals, indicating its potential significance in veterinary dentistry.