• Journal of Preventive Medicine and Public Health
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• v.32 no.4
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• pp.452-458
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• 1999

Objectives: The authors conducted the study to evaluate bias when potentially diseased subjects were included in cohort members while analyzing risk factors of chronic liver diseases. Methods: Total of 14,529 subjects were followed up for the incidence of liver diseases from January 1993 to June 1997. We have used databases of insurance company with medical records, cancer registry, and death certificate data to identify 102 incident cases. The cohort members were classified into potentially diseased group(n=2,217) when they were HBsAg positive, serum GPT levels higher than 40 units, or had or has liver diseases in baseline surveys. Cox's model were used for potentially diseased group, other members, and total subjects, respectively. Results: The risk factors profiles were similar for total and potentially diseased subjects: HBsAg positivity, history of acute liver disease, and recent quittance of smoking or drinking increased the risk. while intake of pork and coffee decreased it. For the potentially diseased, obesity showed marginally significant protective effect. Analysis of subjects excluding the potentially diseased showed distinct profiles: obesity increased the risk, while quitting smoking or drinking had no association. For these intake of raw liver or processed fish or soybean paste stew increased risk; HBsAg positivity, higher levels of liver enzymes and history of acute liver diseases increased the risk. Conclusions: The results suggested the potential bias in risk ratio estimates when potentially diseased subjects were included in cohort study on chronic liver diseases, especially for lifestyles possibly modified after disease onset. The analytic strategy excluding potentially diseased subjects was considered appropriate for identifying risk factors for chronic liver diseases.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.2
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• pp.131-155
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• 1983

Though it has been widely known the nitrogen effects are influenced by soils, varieties, and mineral nutrients in the rice culture, few analyses in relation to the factors increasing nitrogen effect have been studied in Korea. The effects of potassium and silica on the factors increasing nitrogen effects in paddy soils were investigated in accordance with soil improvement practices and nitrogen application methods for the cultivated varieties. The results obtained are as follows. 1. For 413 paddy fields, the yield from soils without nitrogen application ranged from 200 to 850kg/10a and that from nitrogen application did 350 to 1,051kg/10a. The yield increament by nitrogen application varied 50 to 650kg/10a depending on soils. 2. Soil chemical characteristics for high yield were different between with nitrogen and without nitrogen application. In the without nitrogen application, however, contents of organic matter, phosphorous, potassium and calcium of high yield soils were lower than those of low yield, while the available silica content was higher in the former. 3. The yield increased with nitrogen application up to 22.4kg/10a and thereafter it decreased. These phenomena were supposed to be not be decrease of nitrogen uptake but by lowered silica uptake. 4. Clay soil incorporation, deep plough, and inorganic constituents control such as Ca, Mg, and $Sio_2$ were effective as soil improvement praitices. It was appeared that increases of silica content and Ca/Mg ratio were important to increase nitrogen effects. 5. For the correlation between yield and yield components, it was high between yield and panicle in low nitrogen level and so was it between grain yield and ripening rate in high nitrogen. 6. In the urea and super granule urea application plot, recovery rate of nitrogen by plant and soil was high and yield was remarkable high. 7. Regardless of fertilizer types such as ammonium sulfate and urea, the residual nitrogen was about 4kg/10a in both plots of 5.8 and 11.6kg/10a. N applied. 8. The potassium application to soil enhanced the nitrogen efficiency. It was more effective in low potassium soil. 9. Optimum pH value for gel formation in the 4% sodium silicate solution was approximately 6.6. 10. It was suggested that silica could affect to rice plant growth as the inorganic and organic chemical components.

• Microbiology and Biotechnology Letters
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• v.36 no.1
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• pp.61-66
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• 2008

The proteins in whey are separated and used as food additives. The remains (mainly lactose) are spray-dried to produce sweet whey powder, which is widely used as an additive for animal feed. Sweet whey powder is also used as a carbon source for the production of valuable products such as polysaccharides. Glucose, fructose, galactose, and sucrose as asupplemental carbon source were evaluated for the production of PS-7 from Azotobacter indicus var. myxogenes L3 grown on whey based MSM media. Productions of PS-7 with 2% (w/v) fructose and sucrose were 2.05 and 2.31g/L, respectively. The highest production of PS-7 was 2.82g/L when 2% (w/v) glucose was used as the carbon source. Galactose showed low production of PS-7 among the carbon sources tested. The effects of various carbon sources addition to whey based MSM medium showed that glucose could be the best candidate for the enhancement of PS-7 production using whey based MSM medium. To evaluate the effect of glucose addition to whey based media on PS-7 production, fermentations with whey and glucose mixture (whey 1, 2, 3%; whey 1% + glucose 1%, whey 1% + glucose 2% and glucose 2%, w/v) were carried out. Significant enhancement of PS-7 production with addition of 1% (w/v) and 2% (w/v) glucose in 1% (w/v) whey media was observed. The PS-7 concentration of 2% glucose added whey lactose based medium was higher than that of 1% glucose addition, however, the product yield $Y_{p/s}$ was higher in 1% glucose added whey lactose based MSM medium. Therefore, the optimal condition for the PS-7 production from the Azotobacter indicus var.myxogenes L3, was 1% glucose addition to 1% whey lactose MSM medium.

• Journal of Korean Society of Forest Science
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• v.9 no.1
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• pp.61-74
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• 1969

Forest area in Korea ocupies as much as 68 percent of the total land area, but forest production figure in the statistics is rather trifling: that is about 2 percent of Gross National Production (G.N.P.), on the average. In view of the primary industrial sector, its production only weighs no more than 5 percent of this whole sector. Forest production written above refers only to direct forest income of the whole forest income. For the primary forest products they are in many cases used as raw materials for other interrelated industries. The added value there-from, which arises from round about production Process, in other word, indirect income is of most singnificance. Nevertheless, until nowadays forest production has been merely refered to timber production i, e, direct production but indirect income has never been looked upon. In this regard, calculated indirect forest income by means of input ratio method. The material used were Leontiefls tables of two 1963 and 1966 fiscal years, surveyed and analysed by The Bank of Korea. Indirect forest income calculated were 42,688,200,000 won in 1963 and 74,789,800,000 won in 1966 compared direct forest income of 14,361,000,000 won in 1963 and 17,709,000,000 won in 1966. So far as indirect forest income is considered total forest production indices composed of direct and indirect forest income amount to 8.23% in 1963 and 10.12% in 1966 of Gross National Production. Invisuable forest income which originates from, what we cal, indirect benefit of forestry such as land conservation, flood and drought control, soil run off control, scenic beauty and many others is naturall, not included in the calculation. As already mentioned, primary forest products are, for the most part, utilized as raw materials for other industries, therefore indirect forest income is rather appreciable than direct forest income, contributing for the growth and development of other connected industries. In these points of view, forestry must not be evaluated trifling in deciding industrial importances.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.4
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• pp.339-346
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• 1986

A study on eutrophication in the downstream of the Nakdong River was conducted from October 1983 to September 1984. Nutrients concentration of the samples in this area was usually high and the nitrogen ratio to the phosphorus was as very high as $63.5{\sim}119.6$. The concentration of nutrients was in the range of $0.22{\sim}173{\mu}g-at/l$ for ammonia nitrogen, $26.7{\sim}187{\mu}g-at/l$ for nitrate nitrogen, $1.07{\sim}8.22{\mu}g-at/l$ for nitrite nitrogen, $58.7{\sim}231{\mu}g-at/l$ for total inorganic nitrogen and $0.44{\sim}4.43{\mu}g-at/l$ for phosphate phosphorus. The concentration of chlorophyll-a was in the range of $1.8{\sim}75.2\;mg/m^3$. Correlationship between concentration of nutrients and chlorophyll-a was not found. The concentrations of total suspended solid were in the range of $10.7{\sim}45.9\;ppm$, and $16.2{\sim}35.2\%$ of the total suspended solid was consisted of volatile suspended solid. According to the state of lacustrine nutrition, the state of the downstream of Nakdong River was equivalent to the eutrophication state in term of chlorophyll-a and inorganic nitrogen, and mid-nutritional state in term of phosphate.

• Journal of Nutrition and Health
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• v.41 no.8
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• pp.742-753
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• 2008

The purpose of this study is to investigate risk factors of pre-hypertension and hypertension in rural residents. Nine hundred and ninety four subjects aged 40-70 yrs in Chungnam-do participated in this study. The subjects (n = 824) were classified into three groups of hypertensive, pre-hypertensive, and normotensive according to the Joint National Committee (JNC)-7 criteria. The weight, body mass index (BMI), waist-hip ratio (WHR), and serum total protein, albumin, BUN, and triglyceride (TG) were positively correlated with SBP and DBP. After adjusted by age, sex and BMI, the total protein, albumin and TG were significantly correlated with SBP and DBP (p < 0.01). There was no significant difference in eating habits according to the level of blood pressure. The serum albumin, creatinine, Glu-FBS, Glu-PP l20, and triglyceride were higher in both prehypertensive and hypertensive group than in the normotensive group. However, mean serum cholesterol was not different among three blood pressure groups. In this study, the common risk factors of pre-hypertension and hyper-tension were male, age of fifties, lower education level, ex-smoking, higher drinking frequency, higher BMI, body fat %, waist circumference, WHR, serum albumin and diabetes, even though the degree of risks in these variables were higher in the hypertensive group. The higher BUN was a risk factor of prehypertension, while the family history, prediabetes, serum total protein, Glu-PP l20 and higher alcohol drinking amount were the risk factors of hypertension. This result suggests that maintaining good health habit and normal range of blood parameters as well as controlling body weight have to be paid attention in order to prevent hypertention, and further reseasch on the relationship of blood pressure and BUN are needed.

• Advances in pediatric surgery
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• v.16 no.1
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• pp.1-10
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• 2010

The members of the Korean Association of Pediatric Surgeons conducted a retrospective study of two hundred and twenty-two cases of intestinal atresia for the period from January 1, 2007 to December 31, 2009. Seventeen hospitals were involved. There were 76 duodenal, 65 jejunal, and 81 ileal atresias (3 colonic). The male to female ratio was 0.85:1 in DA and 1.34:1 in JIA. Ninety-four patients(43.3 %) were premature babies (DA 40.3 %, JA 64.6 %, IA 28.8 %), and 70 babies (32.0 %) had low birth weight (DA 38.7 %, JA 44.4 %, IA 16.0 %). Antenatal diagnosis was made in 153 cases (68.9 %). However, 27 infants (17.6 %) with antenatal diagnosis were transferred to the pediatric surgeon's hospitals after delivery. Maternal polyhydramnios was observed in 81 cases (36.59 %) and most frequent with proximal obstruction. In forty-four cases (19.8 %), only simple abdominal film was taken for diagnostic study. The associated malformations were more frequently observed in DA - 61.8 % in DA and 22.6 % in JIA. Meconium peritonitis, small bowel volvulus and intussusception were more frequently associated with ileal atresia. The overall mortality rate was 3.6 %. (Abbreviations: DA;duodenal atersia, JA;jejunal atresia, JIA;jejunoileal atresia, IA;ileal atrsia).

• Advances in pediatric surgery
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• v.13 no.2
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• pp.203-211
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• 2007

A nationwide survey on acute appendicitis (AAP) was undertaken among members of the Korean Association of Pediatric Surgeons. The members were required to complete a questionnaire and the case registration form for each patient during the 6 months period from the $1^{st}$ October, 2005 to $31^{st}$ March, 2006. Questionnaires were collected from 23 members. Four hundred seventy six patients were registered from 21 hospitals where the members were working. The male to female ratio was 1.67:1. Average age was 9 years and 5 months (range 21 months-20 years). Operations were performed on average 10.4 hours (range 1-230 hours) from arrival at hospital. The average operation time was 59.1 minutes. The average admission days were 5.8 days (range 2-45 days). The most frequent symptoms were abdominal pain (95.1 %), vomiting (50.6 %) and fever (43.7%). The average duration of symptoms was 42.2 hours (range 1 hour-22 days). Leukocytosis (WBC count > 10,000) was found in 85.9%. The most popular diagnostic tools were ultrasonography and CT. Open surgery was performed in 72.1 % and laparoscopic surgery in 27.5 %. Two laparoscopic surgeries were converted to open surgery (0.4 %). Simple appendicitis was found in 54.5 % and complicated appendicitis such as abscess, gangrenous change and perforation in 45.5%. According to the questionnaires 12 hospitals were performing open surgery only in all patients. Four hospitals were performing laparoscopic surgery in all patients. Seven hospitals are performing both surgical methods according to surgeon or occasion. Regarding the use of antibiotics in acute appendicitis, three kinds of antibiotics were used in 40 % of total simple appendicitis patients. The results showed the trend of management in acute appendicitis in Korea. Especially it is necessary for the members to discuss the use of antibiotics for prophylaxis in the simple appendicitis.

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.429-439
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• 2013

This study was conducted to identify the relationship between environmental factors and algal bloom, and provide information for efficient management based on the results of monitoring the environmental parameters and algal diversity in the Jundai reservoir from March 2011 to October 2013. Little change in the weather conditions was observed during the study period except for a slight decrease in rainfall. Concentration of TN and TP in the reservoir exceeded water quality standards for agriculture and significant correlation between algal growth and environmental factors was observed. Phytoplankton in Jundai reservoir included 6 classes, 40 genus, 62 species, and the phytoplankton abundance was in the range of $1.3{\times}10^4{\sim}2.8{\times}10^6$ cells $mL^{-1}$. The annual average of phytoplankton abundance and Chl-a gradually decreased as TN and TP concentrations decreased. Overall Anabaena sp., Oscillatoria sp., and Microcystis sp. were the dominant species in Jundai reservoir. As the water temperature increased, the dominant species were Anabaena sp., Microcystis sp. and Oscillatoria sp., in that order. Anabaena sp. was dominant from spring to early summer with increase in water temperature and pollutant concentrations, and high correlation with environmental factors was observed. Microcystis sp. was dominant depending on changes in the nutrient levels. In the case of Oscillatoria sp., there was no significant correlation between phytoplankton biomess and Chl-a. However, efficient management of water environment and practical control of algal bloom in small scale reservoir polluted by livestock and farm irrigation should be achieved by identification of the relationship between algal growth and environmental factors.

• Journal of Korean Society of Forest Science
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• v.108 no.1
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• pp.40-49
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• 2019

Coarse woody debris (CWD), which is a component of the forest ecosystem, plays a major role in forest energy flow and nutrient cycling. In particular, CWD isolates carbon for a long time and is important in terms of slowing the rate of carbon released from the forest to the atmosphere. Therefore, this study measured the physiochemical characteristics and respiration rate ($R_{CWD}$) of CWD for Larix kaempferi and Pinus rigida in temperate forests in central Korea. In summer 2018, CWD samples from decay class (DC) I to IV were collected in the 14 forest stands. $R_{CWD}$ and physiochemical characteristics were measured using a closed chamber with a portable carbon dioxide sensor in the laboratory. In both species, as CWD decomposition progressed, the density ($D_{CWD}$) of the CWD decreased while the water content ($WC_{CWD}$) increased. Furthermore, the carbon concentrations did not significantly differ by DC, whereas the nitrogen concentration significantly increased and the C/N ratio decreased. The respiration rate of L. kaempferi CWD increased significantly up to DC IV, but for P. rigida it increased to DC II and then unchanged for DC II-IV. Accordingly, except for carbon concentration, all the measured characteristics showed a significant correlation with $R_{CWD}$. Multiple linear regression showed that $WC_{CWD}$ was the most influential factor on $R_{CWD}$. $WC_{CWD}$ affects $R_{CWD}$ by increasing microbial activity and is closely related to complex environmental factors such as temperature and light conditions. Therefore, it is necessary to study their correlation and estimate the time-series pattern of CWD moisture.