• Journal of Aquaculture
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• v.20 no.4
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• pp.278-288
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• 2007

Shrimp culture in Korea had been rapidly developed during 1990's and the production of farmed shrimp reached 3,268 mt from 2,605 ha in 2001. However the shrimp production decreased to 2,368 mt in 2004 because of the mass mortality due to outbreak of white spot syndrome virus (WSSV). WSSV which is one of the most serious threats associated with cultured shrimp around the world has given the economic damages to shrimp culture industry every year since it was found from the shrimp ponds in the west coast of the South Korea in 1993. Various polyculture technologies of shrimp with shellfish, finfish or seaweeds have been implemented to reduce economic damages by mass mortalities of shrimp. Among them, the polyculture of shrimp with carnivorous fish can suppress or delay the viral outbreak of shrimp ponds because the fish may selectively eat the moribund shrimps infected by virus. To determine the selective predatory effect of river puffer Takifugu obscures on WSSV infected shrimp, postlarvae of Litopenaeus vannamei and Fenneropenaeus chinensis. One-year old river puffers were stocked to four earthen ponds of $1,616-1,848\;m^2$ in surface area as followings: polyculture LvP, L. vannamei ($43.4/m^2$)+puffer ($0.22/m^2$); control Lv, L. vannamei ($46.9/m^2$); polyculture FcP, F. chinensis ($30.3/m^2$)+puffer ($0.25/m^2$); control Fc, F. chinensis ($24.6/m^2$). Ponds of control Fc and polyculture FcP had mass mortalities by WSSV outbreak on the $51^{st}$ and $57^{th}$ days of culture respectively. The shrimps of polyculture LvP and control Lv were harvested on the $95^{th}\;day$. Shrimp survival rates of polyculture LvP and control Lv were 32.4% and 18.2% respectively and shrimp productivity of polyculture LvP was 69.2% higher than that of control Lv. Concentration of nutrients (TAN, $NO_2-N$, $NO_3-N$) was maintained within optimal ranges for shrimp growth although that of polyculture ponds showed at least two times higher than that of control ponds. The results suggest that polyculture of L. vannamei with river puffer is higher than monoculture in survival rate and productivity. In addition, F. chinensis should be carefully cultured because this species shows much higher susceptibility to WSSV than L. vannamei.

• Journal of Aquaculture
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• v.20 no.4
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• pp.270-277
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• 2007

White spot syndrome virus (WSSV) which is the most serious threat to cultured shrimp around the world has given enormous economic damages to shrimp culture industry every year since it was found from the shrimp ponds in the west coast of the South Korea in 1993. WSSV has strong infectivity as well as virulence and it can be rapidly transmitted among shrimps in ponds by cannibalism of infected ones. Polyculture of shrimps with carnivorous fish has been applied in commercial shrimp farms to suppress or delay the viral outbreak because the fish may selectively eat the moribund shrimps infected by virus. To determine the selective predatory effect of a carnivorous fish, river puffer Takifugu obscurus on white shrimp Litopenaeus vannamei, polyculture trials in laboratory scale of WSSV-infected and non-infected shrimps with river puffer were conducted in concrete round tanks of $28.26\;m^2$ in surface area as followings: 1) juvenile shrimps (B. W. 0.62 g) with 5 months old puffer (B. W. 11.60 g) cultured for 8 days, and 2) sub-adult shrimps (B. W. 6.84 g) with 16 months old puffer (B. W. 85.82 g) cultured for 5 days in order to know the effects according to size difference of cultured animals. In polyculture of juvenile shrimp with 5 months old puffer, survival rates of infected and non-infected shrimps were 46.0% and 89.1% respectively and in that of sub-adult shrimp with 16 months old puffer those were4% and 48% respectively. The results showed that puffer tends to selectively prey on virus infected shrimps among infected and non-infected ones in a limited space with although there is difference in predatory rate with age and density of animals. Regardless of different densities and ages of animals as well as health condition of shrimps, however, there were low differences in daily biomass of shrimp consumed per kg body weight of puffer. This finding suggests that puffer preys on healthy shrimps when moribund shrimps were not sufficient. Therefore, farmers should consider the total biomass of puffer as well as density and stocking time when they stock puffer into shrimp ponds for polyculture.

• Sleep Medicine and Psychophysiology
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• v.12 no.2
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• pp.111-116
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• 2005

Objectives: Although many reports have been written on seasonal variations in mood and behavior in foreign countries, few reports have dealt with Korean adolescents, except medical students. The goal of this study was to estimate the frequency of seasonal variations in mood and behavior among Korean high school students. Methods: A total of 656 high school students living in southeastern Seoul participated in this study. The subjects were investigated with the Korean translated version of the Seasonal Pattern Assessment Questionnaire (SPAQ), and their responses were evaluated for seasonal patterns in mood and behavior change according to Kasper's criteria to make SAD (seasonal affective disorder) or SSAD (subclinical seasonal affective disorder) diagnosis. Results: A total of 565 subjects completed the questionnaire and the responses (M：F=324：241) were collected and used for analysis. The mean age was 16.73 (SD=0.65) years, and mean global seasonality score 5.88 (SD=4.72). Of the respondents, 413 (73.1%) reported problems related with seasonal changes. Total prevalence rates were 13.6% for SAD, 10.8% for S-SAD. The estimated frequencies were 5.1% for summer SAD, 3.2% for summer S-SAD, 0.5% for winter SAD and 1.1% for winter S-SAD. The prevalence rate of summer SAD or S-SAD was higher than winter SAD or S-SAD. Conclusion: The subjects showed a higher prevalence rate of summer type than winter type in SAD or S-SAD. These results were similar to those of other studies carried out in East Asian countries. However, the unpleasant feelings resulting from high temperature and humidity in summer rather than depression may have influenced the results. Therefore, it is necessary to make new SAD criteria of the SPAQ suitable for East Asian countries.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.8
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• pp.1165-1170
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• 2010

A method for the determination of four pesticide compounds, urea (isoproturon), bis-carbamate (phenmedipham), thiocarbamate (pyridate) and vinyllidenediamine (nitenpyram) were examined and analyzed by HPLC with C-18 column ($250\;mm{\times}4.6\;mm$, $5\;{\mu}m$ diameter particle size). Mobile phase consisted of deionized water, acetonitrile and 50 mM $KH_2PO_4$ (pH 2.5). Isoproturon and phenmedipham analytical condition was isocratic elution of the column with 50% solvent A (acetonitrile) and 50% solvent B (deionized water); pyridate was 85% solvent A (acetonitrile) and 15% solvent B (deionized water) at a flow rate of 1 mL/min; and nitenpyram analytical condition was 90% solvent A (50 mM $KH_2PO_4$, pH 2.5) and 10% solvent B (acetonitrile) at a flow rate of 1 mL/min. In results, retention times were 6.12, 8.63, 9.40 and 12.76 min for isoproturon, phenmedipham, pyridate and nitenpyram, respectively. All injection volumes were $10\;{\mu}L$ and the limit of quantitation was 0.05 mg/kg for four pesticide compounds, respectively. Recovery rate test was performed with three farm products, rice, apple and soybean. Four pesticide compounds were spiked at concentrations of 0.05, 0.1 and 0.5 mg/kg. The recovery rates were ranged from 70.18% to 118.08% and the standard deviations of all experiments were within 10%.

• Journal of Korean Society of Forest Science
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• v.101 no.4
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• pp.722-728
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• 2012

Climate change affects all biological processes in terrestrial ecosystems including photosynthesis, plant growth and productivity. This study was conducted to investigate the effects of experimental warming on the growth of Quercus variabilis seedlings. One-year-old Q. variabilis seedlings were planted in control and warmed plots in April 2010. The air temperature of warmed plots was increased by $3^{\circ}C$ compared to control plots using the infrared lamp from November 2010. Shoot height and root collar diameter were measured in March 2011 and June 2012, respectively, and aboveground and belowground biomass were also measured in March 2011 and 2012, respectively. Shoot height and root collar diameter were significantly higher in warmed plots than in control plots, except for root collar diameter in March 2011. Increment (mm) of shoot height and root collar diameter were also higher in warmed plots ($529{\pm}30$, $5.6{\pm}0.5$) than in control plots ($464{\pm}28$, $4.5{\pm}0.4$). However, there were no significant differences between warmed and control plots except for root collar diameter. Increment (g/year) of total, aboveground and belowground biomass were higher in warmed plots ($36.88{\pm}6.52$, $11.91{\pm}3.44$, $24.97{\pm}3.73$) than in control plots ($30.59{\pm}5.51$, $8.73{\pm}1.66$, $21.86{\pm}3.88$), however, the differences were not statistically significant. Higher seedling growth and biomass of warmed plots might be related to the enhanced net photosynthetic rates in spring and the extended growing season.

• Journal of Korean Society of Forest Science
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• v.101 no.4
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• pp.626-634
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• 2012

The purpose of this study was to investigate the potential of persimmon vinegar as a functional beverage by analyzing the effects of persimmon vinegar ingestion on the energy substrate during endurance exercise. The healthy male adolescents (n=8) drunk persimmon vinegar ingested trial (PSV) or purified water ingested trial as the control trial (CON) 1 h prior to the exercise with the 60% of maximal oxygen uptake ($\dot{V}O_{2max}$) for 1 h. The exercise intensity was increased to the 80% of $\dot{V}O_{2max}$ and remained until exhaustion. And, the physiological variables, blood components, and amounts of energy oxidation were analyzed. There was no significant difference between trials in physiological variables, and the heart rates after exhaustion were higher in PSV compared to CON. There was no significant difference between trials in blood glucose level, while the blood lactic acids decreased significantly in PSV 30 and 60 minutes after onset of exercise. The free fatty acids concentration increased significantly in PSV from 15 minutes to 60 minutes after onset of exercise. The carbohydrate oxidation decreased significantly in PSV from 45 minutes after exercise and, on the contrary, the fatty acids oxidation increased significantly for the same period. And, fatty acids oxidation was higher in PSV compared to CON even after exhaustion. The respiratory exchange ratio was lower significantly in PSV compared to CON from 30 minutes to 60 minutes after exercise, whereas lower in CON after total exhaustion. The exercise time to exhaustion was 41% longer in PSV compared to CON. These results showed that the persimmon vinegar increase the level of lipids metabolism and decrease sense of fatigue by inhibiting carbohydrate oxidation during moderate intensity exercise, suggesting the possibility of using of persimmon vinegar as exercise functional beverage when ingested 1 h prior to the endurance exercise performance.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.6
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• pp.955-961
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• 2014

This study was carried out to investigate the amounts of vitamin C in 22 sweet potato cultivars cultivated in Korea as well as evaluate the effects of cooking methods on vitamin C contents. Methods for determining vitamin C was validated by determining linearity, specificity, limit of detection (LOD), limit of quantification (LOQ), precision, and accuracy using HPLC. Results showed high linearity in the calibration curve with a coefficient of correlation ($R^2$) of 0.9999. The LOD and LOQ values for ascorbic acid (AA) were 0.03 and $0.10{\mu}g/mL$, respectively. The relative standard deviations (RSDs) for intra- and inter-day precision of AA were less than 5%. The recovery rates of AA and dehydroascorbic acid (DHA) were in the range from 98.21~98.64 and 98.28~100.68%, respectively. Depending on cultivar, contents of AA, DHA, and total ascorbic acid (TA) in sweet potatoes varied in the range from 37.76 (Sinyulmi)~89.25 (Juhwangmin), 23.37 (Sinjami)~63.94 (Sinyulmi), and 68.52 (Sinjami)~115.95 (Juhwangmin) mg/100 g, respectively, and their average levels were $56.98{\pm}12.53$, $36.46{\pm}9.03$, and $93.44{\pm}12.00mg/100g$, respectively. The average TA levels were also dependent on flesh color, whish was significantly higher in general sweet potato and orange sweet potato than in purple sweet potato. Steaming, baking, and frying processes significantly reduced AA (10.61~58.41%), DHA (2.57~52.81%), and TA (14.54~49.92%) contents in sweet potatoes. The highest reduction of AA, DHA, and TA contents was observed after baking, followed by steaming and frying. We expect that the basic information provided by this study will be useful to plant breeders and food scientists.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.6
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• pp.934-942
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• 2014

The purpose of this study was to investigate factors affecting problematic drinking by university students in the Chuncheon area. Lifelong drinking rate of subjects was 98.1%. Problematic drinking rates according to AUDIT (alcohol use disorders identification test) were as follows: 21.3% 'no problem', 58.0% 'at-risk drinking', 10.0% 'alcohol abuse' and 10.7% 'alcohol dependence'. Research has shown that problematic drinking is more prevalent among freshmen, early drinkers, those with hypochondria, and students who are less satisfied with their campus life or whose own parents are frequent drinkers. It has been shown that more serious problematic drinking is associated with higher 'positive alcohol outcome expectancies' and 'coping motives for drinking', and 'recognition level of drinking cultures' is considered less desirable. Multiple regression analysis revealed that 'coping motives for drinking' was the most significant variable affecting the problematic drinking of university students. Developing and fostering various alcohol-reducing programs that largely focus on 'coping motives for drinking' will greatly contribute to solving problematic drinking.

• Journal of Gastric Cancer
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• v.7 no.2
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• pp.82-87
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• 2007

Purpose: In gastric cancer patients with gastric outlet obstruction, there are several complications such as malnutrition and vomiting. Palliative enteral stenting is a less invasive procedure as compared with a gastrojejunostomy. The aim of this study was to determine whether there was a significant difference between patients that undergone palliative enteral slanting and patients that had received a bypass gastrojejunostomy. Materials and Methods: One hundred patients underwent palliative entering stenting and 3f patients were subjected to a surgical bypass gastrojejunostomy. We reviewed the medical records of the patients with gastric outlet obstruction secondary to far advanced gastric cancer that were diagnosed using a gastrofibroscope, UGI and abdominal CT, and were admitted to our institution between January 2000 and August 2006. The outcome of stent placement for gastric outlet obstruction was compared with palliative gastrojejunostomy during the same period. We excluded patients with recurrent gastric cancer and double cancer from this study. Results: There were significant differences between the group of patients that underwent slanting and the group of patients that received a gastrojejunostomy regarding the age of patients ($67{\pm}12$ vs. $57{\pm}9$, P<0.001) but not between the sex of the patients (M : F, 2 : 1 vs. 2 :1, P=0.637). The most common complication of stenting was tumor ingrowth (16/100, 16%) and the second most common complication was stent migration (14/100). Failure of the procedure occurred in only three patients. Twenty-three patients underwent re-slanting and one patient required open conversion with a gastrojejunostomy. The median time to the first meal was $4{\pm}2$ days in the stent group of patients and $6{\pm}2$ days in the gastrojejunostomy group of patients (P=0.001). The median postoperative hospital stays were 9 days in the stent group of patients and 15 days in the gastrojejunostomy group of patients (P=0.003). The mean survival periods were 11 months in the stent group of patients and 10 months in the gastrojejunostomy group of patients (P=0.937). Conclusion: There were no significant differences In the mean survival rates. An earlier first meal and a shorter hospitalization stay were found in the slanting group of patients compared to the bypass gastrojejunostomy group of patients. However, re-slanting was a concern due to tumor ingrowth and stent migration.

• Journal of the Korean Geographical Society
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• v.29 no.3
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• pp.318-339
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• 1994

U.S. had given large amount of cotton to Korea as food aid program since 1945. This cotton aid had negative impact on cotton culture in Korean agriculture. Korean government used counterparts funds (sale proceeds of food aid) not for investment to agriculture sector, but for military budgets. And food aid on program type had influenced general economic policies, which neglected agricultural sector too. Anti-agricultural policy which was helped by U.S. food aid, had caused cotton cultivator an economic loss. So this economic loss had made many farmers abandon cotton culture. But in our times, cotton is cultivated for the purpose of domestic consumption in a few rural villages. The purposes of this study are 1) to analyze the process of spatial reduction of cotton culture since 1945 in regional contexts in Korea, and 2) to identify the function and meaning of cotton culture which does not pay off in agricultural region. Materials for acreage of cotton culture are acquired through the agricultural statistical year book(1952-1989) and census. To clarify the meanings of cotton culture, field survey are conducted in a rural village which is identified as only one where cotton was cultivated in 1993. In these contexts, this study has come to the following conclusions. In the period of under the rule of Japanese Imperialism (1910-1945), G. arboreum, species of cotton which was traditionally cultivated since 1364, had been driven out. And G. hirustun species, which is suitable for the production of highly qualified textile, has been hierarchically diffused by policy. In these period, regional structure of Korean agriculture was reorganized for the provision with food to Japan. Crops leading this dependent spatial structure were rice and cotton. So agricultural region, specialized with cotton, were distributed in the hinterland of the area which is specialized with rice. U.S. cotton aid to Korea began in 1947. U.S. took an interest in agricultural export because of her domestic surplus of cotton. Cotton aid is one mechanism by which U.S government developed agricultural market in recipient countries, Specially in the exchange rates, up-valuation of won to the U.S. dollars made domestic cotton more expensive than cotton imported, Production cost of domestic cotton is higher than Government's purchasing price of cotton which was also more expensive than price of cotton imported. Korean farmer could not help abandoning the cultivation of cotton, and this gave rise to spatial reduction of cotton culture. Spatially, cotton culture was abandoned in early stage of reduction in regions where stand at a disadvantage climatically, and in next stage in regions where other up-land crops which paid off in urban market, eg, fruits, could be cultivated. In the stage of extinction, cotton was cultivated only in area where G. hirustun species was originated in Korean peninsula. This region is not only suitable climatically for cotton culture, but is far away from urban market. Use of cotton produced is not for spinning, but for fillings of comforter. The main purpose of cotton culture in rural village is not for cotton yields, but for increase of production of seasame, which is grown together with cotton as mixed crops. Cotton product are used for domestic consumption and sold out to gin house. Though cotton culture is not paid off, farmer wanted to cultivate continuously for the cultural purpose, and they wanted the cotton culture promotion policy with the goverment subsidy.