• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.2 no.2
• /
• pp.139-146
• /
• 1999

Purpose: The aim of this study was to evaluate the clinical significance of 24 hour pH monitoring in the pediatric patients with recurrent vomiting or regurgitation. Methods: We performed 24 hour pH monitoring on 87 pediatric patients with recurrent vomiting or regurgitation using GastrograpH with glass electrode. The pathologic GER was determined by the reflux index (RI). RIs>10% were considered positive in patients <1 year of age, whereas RIs of >5% were positive in other age groups. We evaluated the mean and standard deviation of the reflux parameters between physiologic and pathologic GER groups, and also compared the reflux indices of each group with respect to time zones of the day. Results: Pathologic GER was found in 32 of 87 patients (36.8%), and the age incidence included 32.5% in infants <6 months old, 13.3% in infants aged 6 months-1 year old, 61.5% in children aged 1~2 years old, 14.3% in children aged 2~3 years old and 66.7% in children >3 years old. In physiologic GER patients, the RI was $3.7{\pm}2.9%$ for the patients <1 year old (group A), and $1.8{\pm}1.5%$ for those ${\geq}1$ year old (group B) which was statistically significant between the 2 age groups (p=0.02). The number of long refluxes more than 5 minutes was significantly increased (p=0.03) in group A ($1.7{\pm}1.9$) than in group B ($0.8{\pm}1.0$). The duration of the longest reflux was significantly longer (p=0.007) in group A ($604{\pm}551$ sec) than in group B ($275{\pm}296$ sec). In pathologic GER patients, the RI was $17.7{\pm}11.6%$ for the patients <1 year old and $7.8{\pm}2.9$ for those ${\geq}1$ year old. The number of long refluxes of more than 5 minutes were $8.9{\pm}4.6$ and $3.2{\pm}1.8$, and the duration of the longest reflux were $1955{\pm}2190$ sec and $1093{\pm}706$ sec for each age group. In both physiologic and pathologic GER patients, there was no significant difference of RI among the time zones of the day. Conclusion: Pathologic GER was found in 36.8% of patients. There was significant difference of RI between those <1 year old and those ${\geq}1$ year old in physiologic GER patients. There was no significant difference of RI among the time zones of the day in both pathologic and physiologic groups. In our study, the frequency of pathplogic GER was too much higher in age group of 1~2 years old (61.5%) than in group of 6 months-1 year old (13.3%), which means that further study is needed to determine the pathologic criteria of RI (Vandenplas criteria is >5%) in the age group of 1~2 years old.

• Journal of Korea Water Resources Association
• /
• v.54 no.11
• /
• pp.875-889
• /
• 2021

This study compares and analyzes the Soil and Water Assessment Tool (SWAT) and Terra MODIS (Moderate Resolution Imaging Spectroradiometer) as coniferous, deciduous and mixed forest with Yongdam Dam upstream (904.4 km²). The hydrologic evaluation period was set to 10 years from 2010 to 2019, and the applicability of the 8-day MOD15A2 Leaf Area Index (LAI) data, 3 TDR (Time Domain Reflectometry) (GB, JC, CC), and 1 Flux Tower (DU) evaporation volume (YDD) data was simulated. As a result, the R² of coniferous forest, deciduous forest and mixed forest are 0.95, 0.89, 0.90, soil moisture and evaportranspiration stations R² were analyzed at 0.50 to 0.55 and 0.51, respectively, with R² at 0.74, RMSE 2.75 mm/day, NSE 0.70 and PBIAS 14.3% for Yongdam inflow. Based on the calibrated and validated watersheds, the annual average evaportranspiration was calculated as coniferous 469.7 mm, deciduous 501. mm and 511.5 mm mixed forest, total runoff were estimated at coniferous 909.8 mm, deciduous 860.6 mm and 864.2 mm mixed forest. In the case of annual average evaportranspiration, it was evaluated that deciduous were high, but in the case of streamflow, it was evaluated that coniferous were high. Unlike other hydrologic with similar patterns throughout the year, the average annual evapotranspiration was about 7% higher than coniferous due to the higher evapotranspiration of deciduous with high leaf area index in summer and fall. In addition, deciduous were 9% and 6% higher for surface runoff and lateral flow, but the groundwater of coniferous was 77% higher. Therefore, it was confirmed that the total runoff was in order of coniferous, mixed forest, and deciduous.

• Journal of Bio-Environment Control
• /
• v.26 no.3
• /
• pp.167-174
• /
• 2017

To identify the appropriate irrigation level for Pinus densiflora, a common reforestation species in Korea, we investigated their growth response characteristics according to different irrigation treatment levels for producing container seedlings with relatively high growth rate for higher survival rate when planted at the reforestation site. The container seedlings including control seedlings (no irrigation was applied) were grown in 104-cell trays were irrigated for 8 weeks from 15 weeks after seeding, at intervals of 1, 2, 3, 5, 7, 10, and 15 days. Analysis of the height growth, root collar diameter growth, and dry matter production of the container seedlings according to irrigation showed that the highest growth reaction was observed for the irrigation interval of 1 day. A shorter irrigation cycle resulted in better growth of the container seedlings, but overall, longer total root length were observed with an irrigation cycle of 3 days compared with cycles of 1 or 2 days. Quality index (QI) was the highest for the irrigation interval of 1 day, and tended to decrease with increase in the irrigation interval. Thus, it was determined that irrigation at intervals of 1-2 days was appropriate for growing Pinus densiflora container seedlings.

• Journal of Nutrition and Health
• /
• v.40 no.8
• /
• pp.736-744
• /
• 2007

Leptin, as an adipocyte-derived hormone, is an important regulator of food intake and energy expenditure. In the cross-sectional study, leptin was shown to be positively related to body adiposity and metabolic disorders in adults. However, there were very few studies which reported the leptin as a predictor of weight gain over time. We examined whether serum leptin can be used as an indicator of the present and 1-year past weight status in very young children. First grade students from elementary schools in Gwacheon City were enrolled in the study since 2005. The study subjects(total 375 students; 195 boys and 180 girls) participated in the investigation of both 2005 and 2006. Physical examinations including height, weight, waist circumference were done. To examine the prevalence of obesity, obesity index was used. Serum leptin was measured, and their nutritional status was also evaluated based on 3-Day dietary records. Serum leptin levels were strongly positively related with the value of the present BMI and with the value of the BMI one year before. We found no association with leptin levels and amount of energy intake and macronutrient intake in this children population. Children were divided into three groups according to leptin tertiles. The highest leptin tertile group showed highest prevalence of obesity in year 2006 as well as in year 2005. Serum leptin levels can reflect the weight status now and as well as 1-year before. Possibly serum leptin levels can predict the weight gain of year later. Without an action against the obesity on children with high leptin level, those children would maintain the excess adiposity growth and progress into the obesity-related metabolic disorders. Further studies are needed to predict the obesity as early as possible and preventive system then after.

• The Journal of Korean Society for School & Community Health Education
• /
• v.3
• /
• pp.35-58
• /
• 2002

This research attempted to investigate the real state of adolescent smoking and drinking, and to study how stress influences on smoking and drinking of high school students. This data was collected from 837 first and second grade students in a vocational high school in Go-yang city, Gyeonggi province. Data analysis consisted of frequency, percentage, Chi-square, T-test, step-wise regression analysis, using SPSSWIN. The results of analysis were as follows: First, 51.7% of the students have never smoked, while 48.3% have experienced smoking. Most students started smoking in the second year of the middle school, though 17.6% of the smokers already started in the elementary school. The strongest motive of initial smoking was curiosity, next the inducement of friends, and 10.9% of them smoked to get rid of stress. Their favorite place for smoking was in the order of the entertainment centers, schools, and private academies. They personally purchased cigarettes mostly at the store. Most of them smoked less than 5 cigarettes a day, but 3.7% smoked more than a pack of cigarettes a day, usually with friends rather than alone. Second, the ratio of drinking was relatively high 78.1%, and their initial drinking experience was most frequent at the third year of the middle school. The initial motive of drinking was mostly curiosity and the inducement of friends, but 10.7% of them started drinking to reduce stress and anxiety. The places for buying alcohol and drinking were bars or restaurants. The ratio of habitual drinking was 45.1%, and the ratio of irregular drinking was 53.3%. 1.8% of the drinking students enjoyed drinking everyday. The amount of drinking varied from half a bottle to two bottles of Soju, and the drinking problem was serious to see that 11% of them drank more than two bottles at a time. Because 84.4% drank in groups with friends, a thorough and systematic supervision and education of the peer group drinking is essential. Third, as for the relationship between personal matters and smoking, it was found that there was a positive relation between smoking and sex, but there was no correlation between smoking and school years. Adolescent smoking was also related with scholastic achievement, the number of friends, and the existence of parents. Fourth, as for the relationship between personal matters and drinking, it was found that there was no correlation between drinking and sex, but there was a positive relation between drinking and school years. Fifth, the average index of stress was students themselves(2.58), school life(2.53), family life(2.19), friends(2.00), and the total index of stress was 2.33. Sixth, there appeared a marginal negative correlation between stress and 'drinking and smoking' in Pearson coefficient of correlation r to see the influence of stress on smoking and drinking. The difference of the average index of stress according to smoking and drinking bears meaningful difference for all students, smokers and non-smokers, drinkers and abstainers in students themselves, school life, family life, friends, and total stress. Smoking has an effect on family life most, school life next, and drinking has an effect on school life most, family life next, with the explanation power of 11% and 9% respectively, in a regression analysis to analyze the factors influencing on smoking and drinking among the factors of stress.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.35 no.4
• /
• pp.395-407
• /
• 2002

A 3D hydrodynamic-ecological coupled model was applied to estimate a food supply to oysters in Geoje-Hansan Bay where is one of the oyster culturing sites in Korea, In this study, the primary productivity (PP) was adopted as an index of food supply, and the spatial patterns of average chlorophyll a concentration during a culturing seasons from September to May of the following year were simulated by the model, The numerical result showed that PP was high in the inner part of the bay and the adjacent areas of Hwado island, but low in the outer. This result indicates that PP is essentially influenced by anthropogenic nutrient loadings in the system. The model was calibrated using the field data in May which is non culturing season of oysters and a simulated phytoplankton biomass agreed fairly well with the observed data ($R^{2}=0.70$, $RE=10.3\%$). The computed food supply varied from 0.19 to $1.27\;gC/m^{2}/day$ with a mean value of $0.62 gC/m^{2}/day$ from September to May. The highest value was showed in May ($1.27 gC/m^{2}/day$) and the lowest was in February ($0.19 gC/m^{2}/day$).

• Journal of Bio-Environment Control
• /
• v.22 no.1
• /
• pp.43-47
• /
• 2013

This study was conducted to develop the most effective method in promoting onion set in cultivars 'Josaengsseondebol' and 'Daeji' for all year-round production. This was done by extending the day length for 41 days. For both cultivars, the period to reach the maximum number of leaves developed was shortened as the exposure to day length increased. Between the two cultivars, 'Josaengsseondebol' reaches its maximum leaf formation for a shorter duration compared with 'Daeji'. In effect to bulb size, cultivar 'Josaengsseondebol' having a night break of 1, 2, and 16 hours light condition had better bulb enlargement compared with the non-treated bulbs. In the case of cultivar 'Daeji', only bulbs exposed to a night break of 2 and 16 hours light condition had better bulb enlargement. The percentage of marketable set yield in cultivar 'Josaengsseondebol' having a night break of 1 hr, 2 hrs, 16 hrs light condition, and control or untreated bulbs were 84%, 92%, 90%, and 6% respectively. In the case of cultivar 'Daeji', treated with a night break of 1 hr, 2 hrs, 16 hrs light condition, and untreated bulbs had a percentage marketable set yield of 7%, 55%, 64%, and 0% respectively. Based on these results, it is therefore concluded that night break treatment is considered to be effective method in promoting off-season onion set cultivation in cultivar 'Josaengsseondebol'.

• Journal of Nutrition and Health
• /
• v.8 no.4
• /
• pp.15-26
• /
• 1975

The purpose of this paper is to investigate the nutrients intake situation and the physical growth and development of junior high school girls in cheju island, the peculiar area in Korea, and to study every possible correlation ketween daily food intake and growth rate of them. Further, it made an attempt to research nutrition problems for them in this area and assist in their growth and development through proper nutritional marragement. The survey was conducted in seven sample schods selected randomly from all three districts -this is Bukcheju-gun, Namcheju-gun and cheju city-of cheju Island. Four hundred eighteen girls, aged thirteen years ald, in second year grade of junior high schools, were provided with prepared questionnaires. For six days, July $16{\sim}21$ in 1975, the respondents filled out the questionnaires. They were asked to keep record of what they ate each meat. Their mitrients intake were analyzed in accordance with their daily food intake records during a six day period. On the other side, including physical growth index calculated by means of weight and hight of the respondents, their school records were also investigated. Critical Ratio as well as percentage calculation were included for statistical analysis. The findings and results abtained are summarized as follows: (1) Living circumstance a) Average numbers of brother and sister in sampled pupils' family were five. b) Niety percent of the respondents were brought up by mother's milk at their infants and 45 percent of them were weaned at the age of 13 to 24 months. c) Fourty-six percent of them revealed irregulity in their meal time. d) The most favorite main dish was boiled rice mixed other cereals (34%), next bread (31%) and boiled noodle (26%), and kimchi was the most papular side dish (64%). (2) Nutrition survey a) The average calorie intake of a pupil per day was 1,783 cal. and the total calorie intake was composed of carbohydrate 73%, pratein 15%, fat 12% respectively. b) Carolie and nutrients were lower than the recommended level, except vitamins A,$B_1$ and Niacin, c) Average protein intake per day was 68g, which was relatively near to the recommended level, but in fact, most of them came from grain which is lacking in essential amino acids. The ratio of animal protein intake to tatal protein intake was 36%. d) Their average animal food intake was proportionated in 14% in their total food intake and the cereals consumed in the largest quantity at the level of 63% out of whole food groups. (3) The results of statistical analysis a) The correlation between the calorie intake and the physical growth index revealed statistical significancy at the level of P<.005. b) The correlation between the protein intake and the physical growth index revealed statistical significancy at the level of .01

• Journal of Intelligence and Information Systems
• /
• v.26 no.1
• /
• pp.119-133
• /
• 2020

Fama asserted that in an efficient market, we can't make a trading rule that consistently outperforms the average stock market returns. This study aims to suggest a machine learning algorithm to improve the trading performance of an intraday short volatility strategy applying asymmetric volatility spillover effect, and analyze its trading performance improvement. Generally stock market volatility has a negative relation with stock market return and the Korean stock market volatility is influenced by the US stock market volatility. This volatility spillover effect is asymmetric. The asymmetric volatility spillover effect refers to the phenomenon that the US stock market volatility up and down differently influence the next day's volatility of the Korean stock market. We collected the S&P 500 index, VIX, KOSPI 200 index, and V-KOSPI 200 from 2008 to 2018. We found the negative relation between the S&P 500 and VIX, and the KOSPI 200 and V-KOSPI 200. We also documented the strong volatility spillover effect from the VIX to the V-KOSPI 200. Interestingly, the asymmetric volatility spillover was also found. Whereas the VIX up is fully reflected in the opening volatility of the V-KOSPI 200, the VIX down influences partially in the opening volatility and its influence lasts to the Korean market close. If the stock market is efficient, there is no reason why there exists the asymmetric volatility spillover effect. It is a counter example of the efficient market hypothesis. To utilize this type of anomalous volatility spillover pattern, we analyzed the intraday volatility selling strategy. This strategy sells short the Korean volatility market in the morning after the US stock market volatility closes down and takes no position in the volatility market after the VIX closes up. It produced profit every year between 2008 and 2018 and the percent profitable is 68%. The trading performance showed the higher average annual return of 129% relative to the benchmark average annual return of 33%. The maximum draw down, MDD, is -41%, which is lower than that of benchmark -101%. The Sharpe ratio 0.32 of SVS strategy is much greater than the Sharpe ratio 0.08 of the Benchmark strategy. The Sharpe ratio simultaneously considers return and risk and is calculated as return divided by risk. Therefore, high Sharpe ratio means high performance when comparing different strategies with different risk and return structure. Real world trading gives rise to the trading costs including brokerage cost and slippage cost. When the trading cost is considered, the performance difference between 76% and -10% average annual returns becomes clear. To improve the performance of the suggested volatility trading strategy, we used the well-known SVM algorithm. Input variables include the VIX close to close return at day t-1, the VIX open to close return at day t-1, the VK open return at day t, and output is the up and down classification of the VK open to close return at day t. The training period is from 2008 to 2014 and the testing period is from 2015 to 2018. The kernel functions are linear function, radial basis function, and polynomial function. We suggested the modified-short volatility strategy that sells the VK in the morning when the SVM output is Down and takes no position when the SVM output is Up. The trading performance was remarkably improved. The 5-year testing period trading results of the m-SVS strategy showed very high profit and low risk relative to the benchmark SVS strategy. The annual return of the m-SVS strategy is 123% and it is higher than that of SVS strategy. The risk factor, MDD, was also significantly improved from -41% to -29%.

• Journal of Intelligence and Information Systems
• /
• v.16 no.3
• /
• pp.121-145
• /
• 2010

University timetabling depending on the educational environments of universities is an NP-hard problem that the amount of computation required to find solutions increases exponentially with the problem size. For many years, there have been lots of studies on university timetabling from the necessity of automatic timetable generation for students' convenience and effective lesson, and for the effective allocation of subjects, lecturers, and classrooms. Timetables are classified into a course timetable and an examination timetable. This study focuses on the former. In general, a course timetable for liberal arts is scheduled by the office of academic affairs and a course timetable for major subjects is scheduled by each department of a university. We found several problems from the analysis of current course timetabling in departments. First, it is time-consuming and inefficient for each department to do the routine and repetitive timetabling work manually. Second, many classes are concentrated into several time slots in a timetable. This tendency decreases the effectiveness of students' classes. Third, several major subjects might overlap some required subjects in liberal arts at the same time slots in the timetable. In this case, it is required that students should choose only one from the overlapped subjects. Fourth, many subjects are lectured by same lecturers every year and most of lecturers prefer the same time slots for the subjects compared with last year. This means that it will be helpful if departments reuse the previous timetables. To solve such problems and support the effective course timetabling in each department, this study proposes a university timetabling support system based on two phases. In the first phase, each department generates a timetable template from the most similar timetable case, which is based on case-based reasoning. In the second phase, the department schedules a timetable with the help of interactive user interface under the timetabling criteria, which is based on rule-based approach. This study provides the illustrations of Hanshin University. We classified timetabling criteria into intrinsic and extrinsic criteria. In intrinsic criteria, there are three criteria related to lecturer, class, and classroom which are all hard constraints. In extrinsic criteria, there are four criteria related to 'the numbers of lesson hours' by the lecturer, 'prohibition of lecture allocation to specific day-hours' for committee members, 'the number of subjects in the same day-hour,' and 'the use of common classrooms.' In 'the numbers of lesson hours' by the lecturer, there are three kinds of criteria : 'minimum number of lesson hours per week,' 'maximum number of lesson hours per week,' 'maximum number of lesson hours per day.' Extrinsic criteria are also all hard constraints except for 'minimum number of lesson hours per week' considered as a soft constraint. In addition, we proposed two indices for measuring similarities between subjects of current semester and subjects of the previous timetables, and for evaluating distribution degrees of a scheduled timetable. Similarity is measured by comparison of two attributes-subject name and its lecturer-between current semester and a previous semester. The index of distribution degree, based on information entropy, indicates a distribution of subjects in the timetable. To show this study's viability, we implemented a prototype system and performed experiments with the real data of Hanshin University. Average similarity from the most similar cases of all departments was estimated as 41.72%. It means that a timetable template generated from the most similar case will be helpful. Through sensitivity analysis, the result shows that distribution degree will increase if we set 'the number of subjects in the same day-hour' to more than 90%.