• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.5
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• pp.476-479
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• 2002

We observed the succession and appearence species of the marine benthic diatoms for the effective seed production of shellfish culture on wave plates in indoor mass culture tanks. Every five days, the existence species and densitiy of diatoms were counted during the 20 culture days. Experimental conditions were 8.5 $\pm$ 0.3$^{\circ}C$ of water temperature, 1.0250$\~$1.0260 of specific gravity, 2,200$\~$13,000 lux of light intensity. The total density of appearence species was rapidly increased with the lapse of time. However, the number of appearence species decreased on the 20th day. The diatoms observed were 10 species; Navicula sp. of, viridula, Cylindrotheca closterium, Licmophora sp., Pleurosisma normnii, Bacillaria Paradoxa Asterionella glacialis, Stephanopuis sp. cf, turris, Entomoneis sp., Odontella aurita and Cocconeis sp, cf, scutellum. Of them, Navicula sp, of, viridula was most dominant throughout the experiment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.6 no.1_2
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• pp.44-48
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• 1973

Since no medium-sized anchovies for skipjack baits are caught during the winter season in the Korean waters, the demand for the live baits in the winter season is met with crawl-stocked anchovies. Authors conducted a test on the wintering of the anchovies which were caught in the early November and acclimated for 22days in a crawl. The wintering crawl was kept in the inlet near Chungmu City, which is situated in the southern coast of Korea, for 4 months through December 1, 1971 to March 31, 1972. 1. The lowest water temperature of $7.2^{\circ}C$ recorded on March 1, caused no significant mortality of the wintering anchovies. However, two operations, moving the crawl and repacling the crawl webbing, brought about a considerable mortality. The mortality of the anchovies, due to the crawl moving to the wintering place two kilometers away from the transient acclimating place, amounted to 1.5 percent in 9 days following the crawl moving. The replacement of the fouled crawl webbing with a new one also caused a mortality amounting to 1.7 percent in 5 days. 2. It is judged that the favorable wintering waters lie in the south and southeast coasts of Keoje Island, the south and southwest coast of Chungmu City, coasts around Namhae Island, and the east coast of Dolsan Island. Jinhae Bay is not suited for the wintering because of its low water temperature in winter 3. The wintering anchovies wvere fed, once a day through the test period, with 4 kg of finely minced fresh anchovy for 57days in the early period, and with 2kg of compound pellet fish food for the rest of the period. Fatness coefficient of the wintering anchovies showed a slight increase in the latter half of the period.

• The Korean Journal of Malacology
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• v.28 no.2
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• pp.125-129
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• 2012

The study describes growth and survival on different kinds of sediment improvements of early spats of the hard clam, Meretrix petechialis. Specimens of the mature hard clam were collected in the intertidal zone of Yeonggwang, Korea, July 2011. After transportation, early spats(shell length $196{\pm}14{\mu}m$) collected in mature hard clam were used. Experiment period were July 7 to August 6 in 2011 (30 days). Sediment improvements used iodine(10 ppm), hydrogen peroxide($H_2O_2$, 5 ppm), sodium hypochlorite (NaClO, 100 ppm), chlorine dioxide($ClO_2$, 100 ppm) and potassium permanganate ($KMnO_4$, 5 ppm). After cultured during 30 days, shell length growth of hard clam were observed $1.04{\pm}0.26mm$ in sodium hypochlorite 100 ppm, $1.03{\pm}0.25mm$ in chlorine dioxide 100 ppm and $1.01{\pm}0.28mm$ in iodine 10 ppm. Survival rate were 31.4% in chlorine dioxide 100 ppm, 12.1% in sodium hypochlorite 100 ppm, 11.6% in iodine 10 ppm, 1.5% in hydrogen peroxide 5 ppm and 0% in potassium permanganate 5 ppm.

• The Korean Journal of Rehabilitation Nursing
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• v.5 no.2
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• pp.180-192
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• 2002

The purpose of this study was to survey basic data for management of elderly day care centers. In this study, occupation, leisure life, and food, clothing and habituation, as well as social relationship, health state and behavior, and general characteristics of subjects were examined to identify the factors affecting their cognition, need and preference of the day care centers. The subjects of this study were 392 elderly, aged 60 years or over, living in Gangnung and neighboring districts. Data were collected by educated interviewers from November 4 through November 22, 2002. The subjects were interviewed face to face, one for one after the interviewee's agreements on the survey. The collected data were analysed with logistic regression analysis by SAS (statistical analysis system). Logistic regression analysis was done to identify affecting factors for cognition, need and preference of the elderly day care centers. The major findings are as follows: 1. The factors affecting cognition for the day care centers were analysed. The subjects with an occupation and a lower satisfaction level of living environment and friendship, who were economically secure enough to manage a sudden accident, showed a higher level of cognition of the day care centers. The subjects with a higher level of mental health state and a lower level of IADL also showed a higher level of cognition. On the general characteristics younger female subjects showed a higher level of cognition. 2. The subjects with a lower level of perceived economic condition who did not own their housing and were not economically safe enough to manage a sudden accident, had showed a higher level of need for the day care centers. It showed that the subjects with a high level of mental health state, a bad eye sight and dental condition, a good perceived health condition, and a lower level of IADL, needed the centers. 3. The subjects who had an occupation, however, not capable of making their own daily expenses, and a low occupation satisfaction level, and who did not own their housing, and were economically poor not enough to manage a sudden accident, showed a higher preference for the day care centers. The subjects with higher levels of friendship satisfaction and perceived health condition, not living with their spouse, and a higher education level, showed a higher preference for the centers. In conclusion, the common factors affecting their cognition, need and preference of the day care centers were occupation, economic security enough to manage accidents, and friendship satisfaction level. Especially, the subjects who had an occupation, however, not economically secure enough to manage accidents, and who did not live in their own housing with a good perceived health condition, showed high levels of need and preference for the day care centers. These results can be used as basic data to develop the efficient elderly day care centers, thus contribute to the elderly welfare in a local community.

• Journal of Aquaculture
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• v.13 no.2
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• pp.107-117
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• 2000

Optima for temperature, salinity and light intensity for Nitzschia closterium, Chlorella salina, I내초교냔 galbana and Tetraselmis subcordiformis, which are widely used in bivalve hatcheries of Shandong Province in China, were estimated. The temperature optimum was 23 $^{\circ}C$ for N. closterium and I. galbana and 25 and 27$^{\circ}C$ for C. salina and T. subcordiformis, respectively. That for salinity was 23${\textperthousand}$ for N. closterium and T, subcordiformis, but was 33${\textperthousand}$ for C. salina and I. galbana. In general, all the four microalgae grew faster under 6,000 lux than under 4,000 lux. Growth of N. closterium was faster at $25^{\circ}C$ and dropped abruptly >$25^{\circ}C$, and that of C. salina and T. subcordiformis progressively increased upto $25^{\circ}C$ but dropped beyond 27$^{\circ}C$. T. subcordiformis was the most eurythermal among the 4 species. For mass culture of microalgae in Korea, N. closterium and C. salina are suitable during spring and autumn but C. salina and I. galbana during summer. T. subcordiformis is suitable for culture throughout the year.

• Journal of Family Relations
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• v.22 no.4
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• pp.135-156
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• 2018

Objectives: This study aim to determine adolescent meal time, which provides the important context of parent-child sharing time. We divided mealtime into family meal and alone meal, and analyzed the time/space context of each meal time as well as the social determinations. Method: We employed adolescents age 10-18 who live with married patents and attends school at the present (n=5,128) from the original data of Korean Time Use Survey. Results: More adolescent were engaged in family meal rather than eating alone in daily bases. However, the trend show difference by day of week and academic grade; family meal are more prevalent in weekends rather than weekdays. As adolescent reaches high school age, the proportion of eating alone beats the proportion of family meal time. Most of the meal occur at home. Having meal outside was relatively scares, especially on weekdays. Tobit and logistic analysis reveal that, on weekday meal, less school hours, more time spent at the private academy, having family leisure event, and long mother's housework hours were positively associated with family meal time. In weekend model, father's education gradient was associated with family meal time, showing higher the father's education level, there were higher chance of having weekend family meal. As for the eating alone, relevant factors were similar with family meal but the directions were the opposite; having family leisure were negatively associated with alone meal, both weekdays and weekend. Long academy hours, meal preparing and leisure alone were positively associated eating alone. Overall, weekday meal time was strongly linked with adolescent daily schedules and time use, while for weekends meal, in both family meal and alone meal, the influence of parent factors were discovered. Conclusion: The results indicates that alone meal and the family meal are not exclusively related but seem to be complementary. Families tend to enjoy family meal yet, there are some necessary situation that adolescent need to be on their own. Increase in ready-made food industries, growing independence of children by age seem partly allow adolescent children to eat alone. Careful attentions may require for monitoring weekends meal situation and the family factor of adolescent in future studies.

• Korean Journal of Environment and Ecology
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• v.35 no.3
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• pp.277-284
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• 2021

This study surveyed the ecological characteristics of Squalidus gracilis majimae at Nakdong River tributary Sinan Stream from January to December 2020. The species inhabited the riverbed that was mostly covered with gravel and sand. The water depth was 27-158 cm, and the average was rather deep at 54 cm. The stream velocity was slow at 0.41±0.19 (0.24-0.86) m/sec. The gender ratio of females to males was 1:0.73. According to the total length-frequency distribution, the age indicated that the group with less than 50 mm in total length was one year old, the group with 70-69 mm was two years old, and the group over 70 mm was three years old. The total length of sexually mature fishes was 50 mm for females and 60 mm for males. The spawning season was from June to July, and the water temperature was 20.9-23.4℃ during the period. The prosperous spawning season was July. The average number of eggs in the ovaries was 1,009 (595-1,630) per matured female, and the matured eggs were yellowish and spherical with a mean diameter of 0.78±0.08 (0.57-0.83) mm. The live foods were S. gracilis majimae Protozoa, attached algae, zooplankton, and aquatic insects. The feeding habits of S. gracilis majimae are omnivorous, but more than 80% of the stomach content was aquatic insects, Chironomidae spp. The larger the size of this species, the greater the amount and frequency of eating aquatic insects, which are animal feeds. The population that ate aquatic insects did not eat vegetable food.

• Korean Journal of Environment and Ecology
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• v.35 no.6
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• pp.601-608
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• 2021

This study surveyed the ecological characteristics of Squalidus multimacultus at Taehwa River tributary Cheokgwa Stream from January to December 2020. The species inhabited the riverbed that was mostly covered with sand. The water depth was 25-164 cm, and the average was rather deep at 68 cm. The stream velocity was slow at 0.21±0.26 (0.16-0.43) m/sec. The gender ratio of females to males was 1:0.99. The age according to the total length-frequency distribution indicated that the group with less than 50 mm (29.4 - 49 mm) in total length was one year old, the group with 50 - 69 mm was two years old, the group with 70 - 89 mm was three years old, and the group over 90 mm was four years old. The total length of sexually mature fishes was 40 mm for both males and females. The spawning season was from July to August, and the water temperatures was 23.8 - 25.4℃ during the period. The prosperous spawning season was August. The average number of eggs in the ovaries was 1,395 (648 - 2,201) per matured female, and the matured eggs were yellowish and spherical with a mean diameter of 0.67±0.24 (0.62 - 0.83) mm. The live foods were of S. multimacultus attached algae, zooplankton, aquatic insects, and Mollusca. The feeding habits of S. multimacultus were omnivorous, but more than 95% of the stomach content was plant-attached algae. The larger the size of this species, the greater the amount and frequency of eating aquatic insects, which were animal feeds. The population that ate aquatic insects did not eat vegetable food.

• Journal of Life Science
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• v.31 no.12
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• pp.1072-1078
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• 2021

The oral pathogen Streptococcus mutans is considered a major causative agent of dental caries in humans. The use of dental hygiene products, including toothpaste and mouthwash, is used for caries control. However, food intake can lead to the recurrence of oral microorganisms. This study aimed to explore why this bacterium dies so quickly during prolonged incubation and to assess whether this growth characteristic is closely associated with the secretion of metabolic products. Notably, the number of live S. mutans cells rapidly declined after 24 hr during the entire period tested, whereas the number of Escherichia coli cells, an indicator strain, remained steady over the same period. To test whether the S. mutans supernatants contained possible signals that accelerated the death of neighbor cells, we obtained the individual supernatants at the above time points. Following pH neutralization, the cells in which the supernatant was supplemented with glucose grew well. However, pH adjustment alone could not fully recover cell growth in conditions in which the supernatant was supplemented, with or without glucose. These phenotypes of S. mutans may be associated with signaling, not only resulting from nutrient depletion. The findings on the survival phenotype of S. mutans provide new insights into cell-cell communication in the biology of this bacterium.

• Journal of Applied Biological Chemistry
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• v.65 no.3
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• pp.173-181
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• 2022

This study was carried out to investigate the residual characteristics of flubendiamide in kale to establish pre-harvest residue limits (PHRL) and the removal efficiency according to the washing solvent and method. Field tests were conducted at two different greenhouses, field 1 (Anseong-si, Gyeonggi-do) and field 2 (Incheon-si, Gyeonggi-do). According to the safe use guidelines kale was sprayed with flubendiamide twice every 10 days and harvested 0 (after 2 h), 1, 2, 3, 5, 7 and 10 days after the final application. The biological half-live of flubendiamide in kale was calculated based on dissipation curves of the pesticide in samples analyzed by liquid chromatography coupled with tandem mass spectrometry. In the analysis, method limits of quantitation (MLOQ) were 0.01 mg/kg, and recoveries performed with two different fortification levels of 10 MLOQ and maximum residue limit (0.7 mg/kg) were 104.2±3.6 and 101.9±10.2%, respectively. The dissipation rate constant of flubendiamide in kales were 0.2437 at field 1 and 0.1981 at field 2. PHRL calculation equations obtained using the dissipation constants estimated as follows: if the residual concentration of flubendiamide in kale on 10 days before harvest is less than 8.0 mg/kg, the residual concentration on the harvest would be under MRL. The removal of flubendiamide from kale was the greatest when it was washed with vinegar (39.8%), followed by baking soda (31.7%), calcium powder (30.2%), neutral detergent (27.2%), and tap water (15.9%). The results of this study would be useful for both farmers and consumers to produce or consume safe agricultural products.