• Korean Journal of Soil Science and Fertilizer
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• v.31 no.2
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• pp.170-176
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• 1998

Nitrogen and phosphorus loads from an agricultural watershed of the Yulmun-chon tributary in the Buk-Han River Basin were quantified based on total amounts of water stream flow. The water quality and soil loss were estimated. Levels of the stream were recorded automatically using the water level meter. The flow velocities, along with the cross-sectional areas of the riverbed, were measured to estimate total amounts of water flow at three monitoring sites in this tributary. Water samples were collected at nine sites with two weeks interval from May to August and analyzed for the water quality parameters. Amounts of soil loss were estimated by the USLE. The size of the Yulmunchon watershed was 3,210 ha, of which paddy and upland soil areas were composed about 41%. The total amounts of soil loss from the watershed areas were estimated to be $13,273Mg\;year^{-1}$, showing 53%, 46% and 0.7% of the soil loss ratio from upland, forest, and paddy areas, respectively. Electrical conductivities and Nitrogen concentrations of the stream water were higher in the lower watershed area than in the upper area. Increments of N were higher for $NO_3-N$ than $NH_4-N$. Nitrate nitrogen was the major N form to pollute the water due to the agricultural activity. Total runoff was about 72% of the total precipitation in the watershed. The maximum loads of T-N and T-P due to the runoff were estimated to be 1,500 and $5kg\;day^{-1}$, respectively. Concentrations of $NO_3-N$ and $NH_4-N$ in the runoff were 13.5 and 1.8 times higher than those in precipitation. The N loads were mainly from soil loss, application of fertilizer, and livestock wastes, which were 52% of total N load. Results demonstrated that reduction of fertilizer use and the soil loss would be essential for water quality protection of the agricultural watershed.

• Journal of Korean Society on Water Environment
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• v.33 no.4
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• pp.460-473
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• 2017

In order to certificate the contamination assessment of heavy metals in surface sediments from the Nakdong river. Surface sediments were collected of 24 sampling sites (main 14st., tributary 10st.) and analyzed for grain size heavy metals contents. Study area mainly composed of sand (avg. 94.1%) and mean grain size was $1.46{\Phi}$ on average. Heavy metals contents (avg. Al: 12.5%, Zn; 74.4, Cr: 45.3, Li: 26.0, Pb: 17.1, Ni: 10.5, Cu: 7.8, Cd: 0.22 mg/kg) were relatively high contents in the composed of fine sediments. In addition, the results of pearson's correlation coefficient showed that most heavy metals and grain size (silt and clay) were highly correlated. The contents of Zn (6st.) and Ni (1st.) evaluated as moderately polluted, Zn (6st.) evaluated as LEL when compared with sediment quality standard of USEPA and Ontario sediment quality guidelines. Most heavy metals contents were I levels that dose not affected the benthos when compared with sediment pollution evaluation standard of NIER. The results of EX, EF, Igeo and CF showed the contents of Zn, Pb and Cd exceed the background contents and distributing of anthropogenic pollution and evaluated as moderately polluted level. And Nm-08 were relatively high level of contamination in the study area. However as results of PLI (less than 1), all sampling sites were evaluated unpolluted level.

• Fire Science and Engineering
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• v.24 no.4
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• pp.12-17
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• 2010

The purpose of this study is to determine how effectively waste tire recycled material mixed with flame retardant work in combating fire. As discovered in the previous study, waste tire mixed with cement mortar has more insulation capacity. However, this mortar is weak against fire. Therefore flame retardant, with a specific proportional mix, will be added to increase its fire prevention capacity. Tests will be made in accordance with ISO 5657 procedures for measuring fire ignition time, flame and shape variation of test pieces at the Building Material Test Institute. The test piece will be set up with horizontal levels having a constant radiation heat of $1{\sim}5W/cm^2$. Temperature transfers and increases from the surface into the interior. Combustible gases result due to pyrolysis, and regular contact is maintained between the fire source and the center of the test piece for assessment purposes. Ignition has not been occurred without adding retardant meaning that there is almost no possibility of ignition of waste tire particle. This fact can be considered as fire load to appreciate a volume of combustion materials. Flame is not occurred due to heat-absorbing effect by adding non-organic series retardant into waste tire particle. Conclusions have been summarized as follows; 1) Combustion of building material can be decreased by adding retardant to waste tire-mixing mortar. But compressive strength and insulation capacity of the material should be measured later. 2) Firing prevention and ignition are main points of building fire. Reasonable fire engineering assessment of interior material should be made for establishing effective disaster prevention system.

• Journal of dental hygiene science
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• v.12 no.5
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• pp.525-534
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• 2012

Study the effect of stress factors and increases in stress at work on the changes in eating behavior and habits and the influence of these changes on the health of dental hygienists. Use the responses of 273 dental hygienists who work in or around the Seoul area after surveying them by post or face to face. The biggest reason for skipping breakfast was having no time (60.4%) and the most desired change in eating habits was over eating (33.0%) while 51.6% responded that they over ate or binge ate due to stress. The largest stress factor was work load 39.6% and subjects responded that after stress the amount of food consumed increased very much for 12.1%, very for 49.8%, indicating increased food consumption than usual. The group with the most job stress had a high level of self stress awareness (p<0.001), nervousness (p<0.01), back pains (p<0.001), optical fatigue (p<0.01), headache (p<0.01) and indigestion (p<0.01). The higher the job stress, the poorer the eating behavior was (p<0.01) and job stress was high for dental hygienists working in dental clinics with less than three dental hygienists (p<0.05). Low eating behavior scores could be seen in groups that took 4 night shifts per week (p<0.05). Job stress scores for high for groups with no break time during work (p<0.001) and these groups showed low eating behavior scores (p<0.01). Furthermore, if high levels of self stress awareness was present, job stress was very high (p<0.001) and eating behavior scores were the lowest (p<0.05). Job stress of dental hygienists impede the eating behavior and habits therefore has a negative influence on their health. There is a need for more efforts to solve this problem and thus maintain the health of dental hygienists.

• The Journal of Korean Obstetrics and Gynecology
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• v.30 no.4
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• pp.18-44
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• 2017

Purpose: The object of this study was to observe the anti-climacterium activity of Gagamguibiondam-tang (GGOT) on ovariectomized (OVX) rats, a well-documented rodent models resembles with women postmenopausal climacterium symptoms, as including cardiovascular diseases, obesity, hyperlipidemia, osteoporosis, organ steatosis and mental disorders. Methods: In this study, anti-climacteric effects were evaluated separated into three categories; 1) anti-obese, 2) anti-uterine atrophy and 3) anti-osteoporotic effects. Five groups were used (8 rats in each group); sham control, OVX control, GGOT 500, 250 and 125 mg/kg administered groups. Twenty-eight days after bilateral OVX surgery, GGOT were orally administered, once a day for 84 days, and then the changes on the body weight and gain during experimental periods, serum estradiol levels, abdominal fat pad and uterus weights with histopathology of abdominal fat pads (total thickness and mean adipocyte diameters) and uterus (total, epithelial and mucosal thickness, percentages of uterine gland regions) for anti-obese and estrogenic effects. In addition, femur, tibia and fourth or fifth lumbar vertebrae (L4 or L5) wet, dry and ash weights, mineral density (BMD), bone strength (failure load), serum osteocalcin and bone specific alkaline phosphatase (bALP) contents, histological and histomorphometrical analyses - bone mass and structure with bone resorption, were monitored for anti-osteoporosis activity. Results: As a result of OVX, noticeable increases of body weight and gains, food and water consumption, weights of abdominal fat pad deposited in dorsal abdominal cavity, serum osteocalcin levels were demonstrated in this experiment with decrease of uterus, femur, tibia and L5 weights, serum bALP and estradiol levels. In addition, marked hypertrophic changes of adipocytes located in deposited abdominal fat pads, uterine disused atrophic changes, decreases of bone mass and structures of femur, tibia and L4 were also observed in OVX control rats with dramatic increases of bone resorption markers, the Ocn and OS/BS at histopathological and histomorphometrical analysis in this study as compared with sham-operated control rats, suggesting the estrogen-deficient climacterium symptoms - obese and osteoporosis were induced by OVX, respectively. However, these estrogen-deficient climacterium symptoms induced by bilateral OVX in rats were significantly inhibited by 84 days of continuous oral treatment of GGOT 500, 250 and 125 mg/kg, respectively. Especially, GGOT 500, 250 and 125 mg/kg showed clear dose-dependent inhibitory activities on the OVX-induced climacterium signs. Conclusion: The results suggest that oral administration of GGOT 500, 250 and 125 mg/kg has clear dose-dependent favorable anti-climacterium effects - estrogenic, anti-obese and anti-osteoporotic activities in OVX rats in this experiment.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.4
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• pp.535-547
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• 2019

In this study, the heavy metal analysis in sediments (surface sediments, sediments cores and settling particles) from Shihwa Lake has been carried out to evaluate the changes of metal pollution levels in sediments after the operation of Tidal Power Plant (TPP). The average concentrations of metals in surface sediments sampled in 2015 were 8% (Cd)~31% (Zn, Hg) lower than in 2009 before TPP operation. Results of calculating the pollution load index (PLI) with 8 metals, the PLI value in 2015 showed a 18% decrease compared to 2009. However, Cu, Zn, Pb concentrations of surface sediments in 2015 at the upper region around industrial complex still exceeded the TEL (threshold effect level) values for sediment quality guideline in Korea. After the operation of TPP, the metal contaminated depths were increasing from 15 cm to 30 cm at S6 site and from 8 cm to 20 cm at S7 site, respectively. Our data showed that the mean concentration of heavy metals in core samples decreased but the contaminated depth increased. The average of the total sedimentation flux for particulate matter increased by 3.2 times from 32.5 g/㎡/d in 2009 to 103.5 g/㎡/d in 2015. This showed that the bottom sediments were resuspended by the operation of TPP, resulting in an increase of particulate matter in the water column. These results suggest that the sediments contaminated with heavy metals seem to be resuspended and relocated due to the water current caused by the operation of TPP. Cr, Cu, Zn, Pb and Cd were highly exceeding the TEL values in the upstream region and accumulated more than 40 cm of sediment depth, indicating that heavy metal contamination through industrial activity were still a serious environmental problem of Shihwa Lake. Although the metal pollution of Shihwa Lake has been slightly reduced, the contaminated sediments with heavy metals inside of Shihwa Lake might be discharged to outer sea after the resuspension by TPP operation. It is necessary for the advanced scientific approach and political decision to drastically reduce the heavy metal pollution of the study region.

• Korean Journal of Veterinary Research
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• v.36 no.4
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• pp.783-794
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• 1996

It has been suggested that ion transport systems are intimately involved in mediating the effects of growth regulatory factors on the growth of a number of different types of animal cells in vivo. The functional importance of the apical membrane $Na^+/H^+$ antiporter in the renal proximal tubule is evidenced by estimates that this transporter mediates the reabsorption of approximately one third of the filtered load of sodium and the bulk of the secretion of hydrogen ions. This study was designed to investigate the pathway utilized by IGF-I in regulating sodium transport in primary cultured renal proximal tubule cells. Results were as follows : 1. $Na^+$ was observed to accumulate in the primary cells as a function of time. Raising the concentration of extracellular NaCl induced an decrease in $Na^+$ uptake compared with control cells in a dose dependent manner. The rate of $Na^+$ uptake into the primary cells was about two times higher in the absence of NaCl($40.11{\pm}1.76pmole\;Na^+/mg\;protein/min$) than in the presence of 140mM NaCl($17.82{\pm}0.94pmole\;Na^+/mg\;protein/min$) at the 30 minute uptake. 2. $Na^+$ uptake was inhibited by IAA($1{\times}10^{-4}M$) or valinomycin($5{\times}10^{-6}M$) treatment($50.51{\pm}4.04$ and $57.65{\pm}2.27$ of that of control, respectively). $Na^+$ uptake by the primary proximal tubule cells was significantly increased by ouabain($5{\times}10^{-5}M$) treatment($140.23{\pm}3.37%$ of that of control). When actinomycin D($1{\times}10^{-7}M$) or cycloheximide($4{\times}10^{-5}M$) was applied, $Na^+$ uptake was decreased to $90.21{\pm}2.39%$ or $89.64{\pm}3.69%$ of control in IGF-I($1{\times}10^{-5}M$) treated cells, respectively. 3. Extracellular cAMP decreased $Na^+$ uptake in a dose-dependent manner($10^{-8}-10^{-4}M$). IBMX($5{\times}10^{-5}M$) also inhibited $Na^+$ uptake. Treatment of cells with pertussis toxin(50pg/ml) or cholera toxin($1{\mu}g/ml$) inhibited $Na^+$ uptake. Extracellular PMA decreased $Na^+$ uptake in a dose-dependent manner(1-100ng/ml). 100 ng/ml PMA concentration significantly inhibited $Na^+$ uptake in IGF-I treated cells. However, staurosporine($1{\times}10^{-7}M$) had no effect on $Na^+$ uptake. When PMA and staurosporine were added together, the inhibition of $Na^+$ uptake was not observed. In conclusion, sodium uptake in primary cultured rabbit renal proximal tubule cells was dependent on membrane potentials and intracellular energy levels. IGF-I stimulates sodium uptake through mechanisms that involve some degree of de novo protein and/or RNA synthesis, and cAMP and/or PKC pathway mediating the action mechanisms of IGF-I.