• Journal of Korean Society of Water and Wastewater
• /
• v.18 no.3
• /
• pp.357-365
• /
• 2004

Effect of artificial circulation on amelioration of water quality in Yeoncho Lake was analyzed using summer data between 1991-2002. Two sites, intake tower area where aeration systems are concentrated in and near the inlet of reservoir were selected for comparison in this study. Summer averages between may and september Showed that aeration system might be beneficial in the improvement of water quality of BOD5, COD, and TN while Chl-a concentration and transparency did show opposite pattems. Wilcoxon's singed rank test for matched pair indicated slight increase of BOD5 and COD concentrations in the vicinity of intake tower while other variables did not show any significant differences from data of inlet of reservoir. During the study, it was found that the following subjects need to be investigated for more detailed analysis. 1) Dynamic pollutant loading from outside and inside the lake, 2) Biological, Chemical and Physical lake data when aeration systems are in and not in operation and 3) Radius of influence of aeration system.

• Journal of Community Nutrition
• /
• v.4 no.3
• /
• pp.180-186
• /
• 2002

The food attitudes of 285 Korean female students attending a secondary school in Seoul were examined with respect to the 5 food groups of the Korean Food Tower : grain products, vegetables and fruits, meat, milk, and fats and sweets. An instrument with 22 items was utilized to measure food attitudes toward the five food groups. The items were categorized into five factors through factor analysis to obtain a description of the participants' food attitudes. The five factors are conscious choice of food, health concerns, economics and time influence, interest in foods, and foods that energize. Several facts emerged from examining the food attitudes. The most evident was their response to the items concerning the influence of economics and time on food choice, which the majority consider not limiting their food consumption. Most participants gave favorable responses for vegetables and fruits on all the five factors, but gave unfavorable responses for meat group and fats and sweets in health concerns. They also gave favorable responses for“foods that energize”for all except fats and sweets. Four of the total 25 relationships among food intake (five groups) and food attitudes (five factors) were found to have significant positive correlations (p < .01). (J Community Nutrition 4(3) : 180∼186, 2002)

• Korean Journal of Ecology and Environment
• /
• v.41 no.3
• /
• pp.360-366
• /
• 2008

The spatial and temporal variations of the high turbid water by a single event of heavy rain (total 299.1 mm and daily maximum 99.4 mm) were studied in Andong Reservoir, which has hypolimnetic discharges. Turbid water entered into the reservoir, was isolated from the bottom at the midreservoir and then passed through the metalimnion as an interflow current in the lacustrine zone. Maximum turbidity was 290 NTU at 16 m depth of the midreservoir, but the initial turbidity showed about 10 NTU in the reservoir before the rainfall. Turbid water in the reservoir affected to increase the withdrawal turbidity from the 3rd day after the rainfall, the maximum turbidity was 129 NTU at 5th day after the rainfall. Turbid water that flew towards the downreservoir distributed within 5 m above the outlet gate of the intake tower, showing the maximum turbidity, and that was decreased in its thickness and concentration by discharging through the intake tower. It has taken 38 days until the turbidity in the withdrawal reduced to 30 NTU, and 87 days to reduce the turbidity to the way when it was before the rainfall, with the correlation coefficient of 0.96 and 0.97, respectively. Turbid water was withdrawn from the reservoir by entraining into the intake tower as a form of the interflow, and not be settled down to the bottom of the reservoir. Therefore, we assessed that the depth of the withdrawal was appropriately positioned in Andong Reservoir, so as to withdraw the turbid water effectively from the reservoir.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.6
• /
• pp.17-24
• /
• 2020

In this study, series of nonlinear seismic analysis were performed on a reinforced concrete intake tower surrounded by water. To consider the fluid effect around the structure, analysis models were composed using an added mass and CEL approach. At this time, the implicit method was used for the added mass model, and the explicit method was used for the fluid structure interaction model. The input motions were scaled to correspond to 500, 1000, and 2400 years return period of the same artificial earthquake. To estimate the counteractivity of the fluid coupled model, models without fluid effect were constructed and used as a reference. The material models of concrete and reinforcement were selected to consider the nonlinear behavior after yielding, and analysis were performed by ABAQUS. As results, in the acceleration response spectrum of the structure, it was found that the influence of the surrounding fluid reducing the peak frequency and magnitude corresponding to the fundamental frequency of the structure. However, the added mass model did not affect the peak value corresponding to the higher mode. The sectional moments were increased significantly in the case of the added mass model than those of the reference model. Especially, this amplification occurred largely for a small-sized earthquake response in which linear behavior is dominant. In the fluid structure interaction model, the sectional moment with a low frequency component amplifies compared to that of the reference model, but the sectional moment with a high requency component was not amplified. Based in these results, it was evaluated that the counteractivity of the additive mass model was greater than that of the fluid structure interaction model.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2010.04a
• /
• pp.638-639
• /
• 2010

• Journal of Korean Society of Water and Wastewater
• /
• v.21 no.3
• /
• pp.341-348
• /
• 2007

The efficiency of powdered activated carbon (PAC) for removing taste and odor (T&O) in drinking water supplies is dependent on the contact time, quality of mixing, and the presence of competing compounds. All of these are strongly influenced by the stage in the treatment process at which the PAC is added. In conventional water treatment plants (WTPs), PAC is commonly added into the rapid mixing basin where chemicals such as coagulants, alkaline chemicals, and chlorine, are simultaneously applied. In order to prevent interference between PAC and other water treatment chemicals, alternative locations for addition of PAC, such as at transmission pipe in the water intake tower or into a separated PAC contactor, were investigated. Whatever the location, addition of PAC apart from other water treatment chemicals was more effective for geosmin removal than simultaneous addition. Among several combinations, the sequence 'chlorine-PAC-coagulant' produced the best result with respect to geosmin removal efficiency. Consequently, when PAC has to be applied to cope with T&O problems in conventional WTPs, it is very important to prevent interference with other water treatment chemicals, such as chlorine and coagulant. Adequate contact time should also be given for adsorption of the T&O compounds onto the PAC. To satisfy these conditions, installation of a separated PAC contactor would be the superior alternative if there is space available in the WTP. If necessary, PAC could be added at transmission pipe in the water intake tower and still provide some benefit for T&O treatment.

• Korean Journal of Ecology and Environment
• /
• v.34 no.4 s.96
• /
• pp.327-336
• /
• 2001

Physical, chemical, and biological parameters were measured during the period from July 1993 to August 1994 near the Munui intake tower of Taechung Reservoir to evaluate effects of nutrients and suspended solids on algal chlorophyll-a and water clarity. Large amounts of precipitation during summer 1993 produced minimum conductivity ($88\;{\mu}S/cm$), minimum TN : TP (<40), and maximum total phosphorus (TP;$59\;{\mu}g/L$) and resulted in a chlorophyll-a peak ($79\;{\mu}g/L$) and minimum transparency (<1.5 m) among the seasons. At the same time, ratios of volatile suspended solids (VSS): non-volatile suspended solids (NVSS) were maximum (13.0),indicating that the reduced transparency was mainly attributed to biogenic turbidity in relation to phytoplankton growth. In contrast, severe drought in summer 1994 resulted in greater conductivity (>$120\;{\mu}S/cm$), water clarity (%gt;2 m), and lower TP and chlorophyll- a (<$10\;{\mu}g/L$) relative to those of summer 1993. Total phosphorus ($R^2=0.46$, n=59) accounted more variations of chlorophyll- a compared to total nitrogen ($R^2=0,29$, n=59). The mass ratios of TN : TP ranged from 39 to 222 and were strongly correlated with TP (r = -0.80) but not with concentrations of TN (r = 0.05). Ambient nutrient concentrations and TN : TP mass ratios indicated that seasonality of chlorophyll- a was likely determined by concentrations of phosphorus reflected by the distribution of rainfall. It was concluded that reductions of phosphorus during heavy rainfall may provide better water quality for the drinking water in the intake tower.

• Korean Journal of Community Nutrition
• /
• v.5 no.3
• /
• pp.513-521
• /
• 2000

The purpose of this study was to promote health for elementary school children. It was conducted with a 7 week program focused on the teaching of the food tower and evaluation of its educational effects. Subjects consisted of 75 boys and girls (control group : 37, treatment group : 38) in the 4th grade of elementary school. The results showed as follows. The proportion of boys was a little higher than that of girls. Of their mothers age, the thirties and forties were 66.7% and 33.3%, respectively. 61.3% of mothers had jobs and 86.7% of mothers prepared meals. The average of the anthropometric data of the 2 groups show were all in the normal range. The degree of nutritional knowledge in treatment group after education was significantly increased in all concepts, however, the degree of the control group appeared to show significant increase in only two concepts, such as "snack" and "one-sided diet". The diversity of dietary intake was investigated to evaluate the educational effect using food picture cards. The treatment group showed significant increase in all food groups except "cooked rice", "potatoes" and "fruits", but the control group showed no significant change. The level of nutrition knowledge has a significant correlation with the dversity of the food intake in the treatment group. The preferred lesson for children were "games", "doll playing" and "role playing". The impressive lesson contents were "diverse food intake without one-sided diet", "eating breakfast everyday", "choosing good snacks for health" and "eating less procesed food". These findings indicate that a well-designed program for nutrition education can help to change food habits, and that childrens education helps them to grow and to live as healthy adults. The performance of an educational program for preventive nutrition is more beneficial for children than for the adults based on the cost reduction and effect of this education. nutrition is more beneficial for children than for the adults based on the cost reduction and effect of this education.

• Korean Journal of Community Nutrition
• /
• v.11 no.5
• /
• pp.587-597
• /
• 2006

This study was performed in order to identify nutritional factors affecting on skin sebum content with 131 female university undergraduates in 2003. We measured the sebum contents of 4 facial spots to classify their skin types. Daily energy and nutrient intakes of the subjects were not deficient except in calcium and iron, which were 466.2 mg (66.6% RDA) and 8.5 mg (53.4% RDA) relatively. We observed no significant difference of energy and nutrient intakes among the 3 skin types. But significantly higher consumption of grains and slightly higher frequencies of several food groups (excepting starches) were shown in oily skin types, so they might have higher nutrient intakes. Serum indices and food preferences mostly revealed no difference among the 3 skin types. But in the oily skin type, serum phosphorus levels were significantly lower than others, suggesting phosphorus-rich food consumption like soft drinks and pains could lead to a dry skin type rather than an oily one. Also in the oily skin type, sweet taste preference was slightly tower than others; more-over, sweet intake was lower samely significantly. There was mostly no significant relationship between facial sebum contents and nutrient intakes, dietary behavior, food frequency and food preference except in some factors. Animal protein intake showed a significant negative relationship toward facial sebum content. On the other hand, in normal skin type, Fishes consumed was slightly higher than others, so that higher animal protein consumption presumably leads to normal skin type. Frequency of fried food and bacon and preference of fried foods showed slightly negative relationships toward facial sebum content. Regular meal times showed significantly increased facial sebum content.

• Journal of Korea Water Resources Association
• /
• v.32 no.2
• /
• pp.131-142
• /
• 1999

In this study, one and semi-two dimensional numerical models were applied to study on the hydraulic and sedimentologic characteristics of upstream and downstream channel section near the Buyeo intake towers. The HEC-6 model was applied for the simulation of one dimensional sediment movement from 1988 to 1996, and GSTARS model was applied for the simulation of semi-two dimensional sediment movement for the same period. After the verification of accuracy of HEC-6 and GSTARS models, the models were applied again to predict the sediment movement near intake towers from 1988 to 2001. In this case, measured channel section of 1988 was used as an initial channel condition, and used to predict the long-term variation of channel section of 2001 after 13 years since 1988. The simulation results show that the channel bed is sedimented and eroded repeatedly in the main channel of overall study area, and that channel bed is getting elevated in the near Buyeo intake towers.