• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.355-361
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• 2006

In this study, effects of influent C/N(COD/Nitrate) ratio and dissolved oxygen(DO) concentration on biological nitrate removal from groundwater were investigated in the fixed-type biofilter. Influent nitrate of 30 mg/L was removed completely by biological denitrification at the C/N ratio of 10 and 4.0, while residual nitrate of 5 mg/L occurred at the C/N ratio of 2.0, which resulted from deficiency of organic electron donor. Furthermore, nitrite was accumulated up to about 5 mg/L as the C/N ratio decreased to 2.0. Increase in DO concentration also inhibited denitrification activity at the relatively high C/N ratio of 5.0, which decreased the nitrate removal efficiency. Although the influent DO concentration was reduced as low as 0.3 mg/L using sodium sulfite($Na_2SO_3$), effluent nitrite was up to 3.6 mg/L. On the other hand, nitrate was completely removed without detection of nitrite at the DO concentration of 0.3 mg/L using nitrogen gas($N_2$) sparging. The organic matter for denitrification in biofilter were in the range from 3.0 to $3.5gSCOD/g{NO_3}^--N$, while utilized these values increased at the high DO concentration of 5.5 mg/L. In addition to the high DO concentration and the low influent C/N ratio, DO control by chemical such as sodium sulfite affected on biological denitrification, which resulted in the reduction of nitrate removal efficiency and nitrite build-up in a biofilter.

• Korean Journal of Environmental Agriculture
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• v.8 no.2
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• pp.128-135
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• 1989

To find the effects of solar energy into the rice canopy and its balance on the rice plant growth, a Tongil type rice, Raekyeong and a japonica rice, Koganebare were used with four levels of nitrogen fertilizer application, 6, 10, 14, and 18kg $l0a^{-1}$ in Chigugo, Japan. The micrometerosological data, the solar radiation and absorbed solar radiation by the rice plants, and leaf area index on cardinal growth stage of the rice community were measured. The results are as follows : Raekyeong showed increased LAI by increased nitrogen fertilizer application rates, and larger LAI than Koganebear. 1. There was no difference in total dry weight till 20 days after transplanting regardless of nitrogen levels in the same variety, after that, however, Raekyeong showed higher dry matter productions for the same durations than Koganebare. 2. In early growth stage of transplanting rice, reflection ratio of solar radiation above the crop canogy was about 6%, however, it was increased up to 20% by the increased LAI at heading date. 3. In high levels of nitrogen application plots, LAI were increased so that values were decreased. 4. Relationship between the amount of absorbed radiation by plants and its dry matter production was linearly significant. Higher levels of nitrogen application produced higher dry matter in Raekyeong, however, in lower level, the dry matter production pattern was almost similar between both rice cultivars.

• Korean Journal of Environmental Agriculture
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• v.25 no.1
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• pp.85-92
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• 2006

Fungicides including keroxym-methyl (strobilurin fungicide), fenarimol and trifulmizole (DMI, boscalid (anilide) and metrafenone (benzophenone) were evaluated for preventive and curative efficacies against powdery mildew on oriental melon. The fungicides were applied preventatively at 7 days, 3 days and 3 hours before inoculation. Curative applications were made by applying fungicides three times at the interval of one week when infected leaves by powdery mildew were about 16% or 30%. Then preventative and curative efficacies were evaluated one week after inoculation and final application, respectively. Boscalid and metrafenone showed preventive efficacies of 74.3 and 68.3% against powdery mildew development respectively, when treated at 7 days before inoculation. They showed 89.4 and 87.2% efficacies when treated at 3 days before iniculation and 98.5 and 93.2% at 3 hours before inoculation respectively. However, there were no preventive efficacies in kresoxym-methyl, triflumizole and femarimol (DMI fungicides) when trebled at both 7 and 3 days before inoculation. At the preventive treatment 3 hours before inoculation, they indicated 59.0, 42.5, and 37.2% efficacies, respectively. When leaves were infected about 30% by powdery mildew, curative application of boscalid and metrafenone showed 85.9 and 74.0% of efficacies, respectively. Curative efficacies of kresoxym-methyl, tiflumizole and fernarimol were 5.5, 23.0 and 46.7% respectively. When leaves were infected about 16%, curative application of boscalid and metrafenone showed 100 and 97.5% of efficacies, respectively. However, the triflumizole and fernarimol showed relatively low curative efficacies of 30.8 and 51.6%, respectively. Microscopic observation of mycelial growth and conidia formation after detection of powdery mildew disease indicated lysis of mycelium and these lysis suppression of conidia formation showed tendency in accordance with curative efficacies of fungicides.

• Korean Journal of Environmental Agriculture
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• v.25 no.1
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• pp.25-33
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• 2006

Objectives of this experiment were to select of the optimum water plant and to investigate the removal efficiency of the major nutrients in the constructed wetland by natural purification method for municipal sewage treatment in the farming and fishing village. For the experiment we used "constructed wetland" which was consisted of aerobic (vertical filter system) and anaerobic systems (horizontal filter system). Both systems were filled with gravel and filter media, and grew water plants on top of them. And then, we investigated several items such as sewage treatment efficiency, growth status of water plants and the absorbed amount of inorganic element in water plants with periodical periods. In aerobic area, removal efficiencies of BOD, COD, T-N and T-P were over 92%, 74%, 25% and 57%, respectively, and then when the water is passed through anaerobic area, the efficiency was over 96%, 84%, 44% and 71%, respectively, which was increased more treatment efficiency than that of aerobic area. Absorption amount of nitrogen and phosphorous in Miscanthus sacchariflorus BENTH were the highest in the water plants as 17.7 and 2.41 g/plant in the aerobic area, respectively. Absorption amounts of nitrogen and phosphorous in Scirpus tabernaemontani GMEL were the highest in the water plants as 8.7 and 1.13 g/plant in the anaerobic area, respectively. For the selection of optimum water plants in the constructed wetland by natural purification method for municipal sewage treatment, it were observed that there were Miscanthus sacchariflorus BENTH, Phragmites japonica STEUD and Phragmites communis TRINIUS in the aerobic area and were Zizania latifolia TURCZ, Scirpus tabernaemontani GMEL, Typha orientalis PRESL, Iris pseudoacorus L and Cares dispalata BOOTT in the anaerobic area.

• Korean Journal of Environmental Agriculture
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• v.12 no.1
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• pp.27-34
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• 1993

This experiment was conducted to determine the residual amount of dimepiperate (S-1-methyl-1-phenylethyl piperidine-1-carbothioate) and dimepiperate-OH(S-1-methyl-1-phenylethyl-4-hydroxy piperidine-1-carbothioate) in surface water and leachate using a lysimeter system. In surface water, the concentration of dimepiperate was 851-897 ppb in the treatment of 3.0 Kg prod/10a. 1,755-1,781 ppb in the treatment of 6.0 Kg prod/10a 1 day after the treatment. The amount of dimepiperate gradually decreased and was infinitesimal from 35 days after the treatment. In leachate dimepiperate was detected from the 45 days, but its concentration was very low, below 1 ppb, compared to that in surface water. The metabolite of dimepiperate, dimepiperate-OH in surface water was detected after the application of dimepiperate. The highest level of 88-173 ppb occurred 2 day after the treatment of dimepiperate and then decreased gradually. The residual concentration was below 2.13 ppb during 28-63 days. In leachate, the concentration of dimepiperate-OH in the different treatments in the range of 0.5-11 ppb from the 21 days, although each treatment showed different detected date and concentration. The detected concentration showed a little change until 63 days.

• Journal of Bio-Environment Control
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• v.6 no.4
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• pp.250-257
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• 1997

Stem diameter and shoot fresh weight of tomato grown in greenhouse were measured non-destructively at 10 minutes interval from 1 to 16 July, 1996 with displacement detector using strain gauges and with suspension-type load cell, respectively, and simultaneously were measured soil water potential, transpiration and solar radiation. Ample water was irrigated before experiment, and thereafter, irrigations were made on the next morning when visual symptoms of wilting appeared. Shoot fresh weight and stem diameter showed very similar patterns in diurnal changes which are characterized by predawn maximum and afternoon minimum and in long- term evolutions, suggesting that stem diameter shrinkage and expansion are closely related to plant water content and growth, respectively, Shoot weight and stem diameter reached minimum values a little later than the time on which transpiration showed maximum. The daily net gains of fresh weight(DG) and stem diameter(DI) showed significantly Positive correlations with solar radiation in those days on which plants were not water-stressed. However, Dl and DG on those days of water stress showed much lower values than expected from the relationships between solar radiation and them. Transpiration was much lower than the expected potential transpiration on 10 July, implying that plants were water-stressed. In this case water stress was not detected from visual symptom of wilting and/or soil water potential, but was able to be identified by the lower DI and DG than the expected. The maximum contraction of stem diameter(MC) and the maximum loss of fresh weight(ML) during daytime showed significantly positive correlations with solar radiation in those days on which plants were not water-stressed and were observed greater than expected from the relationships on severely water-stressed days. But mild water stress could not be discernable by ML and MC. It would be concluded that the daily net gains of fresh weight and/or stem diameter could be used as criteria for diagnosing the water status of tomato and for triggoring the onset of irrigation in automatic system.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1058-1064
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• 2005

This research was designed to investigate the removal of anionic species, such as $F^-$, $Cl^-$ and ${NO_3}^-$, by adsorption on the clay minerals. Bentonite, $Ca^{2+}$ or $Na^+$ ion exchanged bentonite and montmorillonite, such as KSF and K10 from Sigma Aldrich, were used as the adsorbent. The component of five inorganic adsorbent was analyzed by XRF and XRD and the concentration of anion was measured by ion chromatography. From the experimental results, it was shown that the adsorption equilibrium was attained after 8-24 hours. For the amount of 6 g of each adsorbent, the adsorption capacities of $F^-$ and ${NO_3}^-$ on KSF was the largest as $825\;{\mu}g/g$ and $707\;{\mu}g/g$ respectively and that of $F^-$ on $Ca^{2+}$ ion exchanged bentonite was $255\;{\mu}g/g$ and that of ${NO_3}^-$ on K10 was $103\;{\mu}g/g$. In general, the efficiency of removal for the anionic species was increased with increasing of the amount of the adsorbent. Especially, for the amount of 6 g of KSF, the efficiency of removal for $F^-$ and ${NO_3}^-$ was 99% and 95% respectively. But, for all adsorbents, the efficiency of removal for $Cl^-$ was less than 9%. Also, a Freundlich equation was used to fit the acquired experimental data. As the result, for the $F^-$ and ${NO_3}^-$ on KSF, Freundlich constants, K, was respectively 1.09 and $0.45\;[mg/g][L/mg]^{1/n}$ and the adsorption intensity(1/n) was determined to be 0.08 and 0.27 respectively.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.9
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• pp.1035-1043
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• 2007

A leachate containing an elevated concentration of organic and inorganic compounds has the potential to contaminate adjacent soils and groundwater as well as downgradient areas of the watershed. Moreover high-strength ammonium concentrations in leachate can be toxic to aquatic ecological systems as well as consuming dissolved oxygen, due to ammonium oxidation, and thereby causing eutrophication of the watershed. In response to these concerns landfill stabilization and leachate treatment are required to reduce contaminant loading sand minimize effects on the environment. Compared with other treatment technologies, leachate recirculation technology is most effective for the pre-treatment of leachate and the acceleration of waste stabilization processes in a landfill. However, leachate recirculation that accelerates the decomposition of readily degradable organic matter might also be generating high-strength ammonium in the leachate. Since most landfill leachate having high concentrations of nitrogen also contain insufficient quantities of the organic carbon required for complete denitrification, we combined a shortcut biological nitrogen removal (SBNR) technology in order to solve the problem associated with the inability to denitrify the oxidized ammonium due to the lack of carbon sources. The accumulation of nitrite was successfully achieved at a 0.8 ratio of $NO_2^{-}-N/NO_x-N$ in an on-site reactor of the sequencing batch reactor (SBR) type that had operated for six hours in an aeration phase. The $NO_x$-N ratio in leachate produced following SBR treatment was reduced in the landfill and the denitrification mechanism is implied sulfur-based autotrophic denitrification and/or heterotrophic denitrification. The combined leachate recirculation with SBNR proved an effective technology for landfill stabilization and nitrogen removal in leachate.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.31-38
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• 2020

The characteristics of ship traffic routes and the long term fluctuation in marine traf ic volume of the incoming and outgoing routes of the Yeosu Gwangyang Port were analyzed using vessel traffic data from the past 22 years and a real-time vessel traffic volume survey performed for 72 hours per year, for three years, between 2015 and 2017. As of 2017, the number of vessels passing through Yeosu Gwangyang Port was about 66,000 and the total tonnage of these ships was about 804,564 thousand tons, which is a 400 % increase from the 189,906 thousand tons shipped in 1996. Specifically, the dangerous cargo volume was 140,000 thousand tons, which is a 250 % increase compared to 1996. According to the real-time vessel traffic volume survey, the average daily number of vessels was 357, and traf ic route utilization rates were 28.1 % in the Nakpo sea area, 43.8 % in the specified sea area, and the coastal area traf ic route, Dolsan coastal area, and Kumhodo sea area showed the same rate of 6.8 %. Many routes meet in the Nakpo sea area and, parallel and cross passing were frequent. Many small work vessels entered the specific sea area from the neighboring coastal area traffic route and frequently intersected the path of larger vessels. The anchorage waiting rate for cargo ships was about 24 %, and the nightly passing rate for dangerous cargo ships such as chemical vessels and tankers was about 20 %. Although the vessel traffic volume of Yeosu Gwangyang Port increases every year, the vessel traffic routes remain the same. Therefore, the risk of accidents is constantly increasing. The route conditions must be improved by dredging and expanding the available routes to reduce the high risk of ship accidents due to overlapping routes, by removing reefs, and by reinforcing navigational aids. In addition, the entry and exit time for dangerous cargo ships at high-risk ports must be strictly regulated. Advancements in the VTS system can help to actively manage the traffic of small vessels using the coastal area traffic route.

• Journal of Bio-Environment Control
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• v.23 no.2
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• pp.116-122
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• 2014

This study was conducted to find out the appropriate packaging materials to extend the storability and maintain the quality of cherry tomato for modified atmosphere (MA) storage. Tomatoes were grown by hydroponic at a plastic house in Gangwon Province. Light red maturity stage tomatoes were harvested and packed with MA condition (10,000; 20,000; 40,000; 60,000; 80,000; and $100,000cc/m^2.day.atm$ $O_2$ permeability film) and perforated film to store at $5^{\circ}C$, $11^{\circ}C$ and $24^{\circ}C$. The fresh weight loss was less than 0.6% in all non-perforated breathable films at $^5{\circ}C$, $11^{\circ}C$, and $24^{\circ}C$, but perforated film had less than 2.93% at $5^{\circ}C$, 13.29% at $11^{\circ}C$ and 27.24% at $24^{\circ}C$. The 20,000cc at $5^{\circ}C$ and $11^{\circ}C$, and the 40,000cc film at $24^{\circ}C$ balanced optimum carbon dioxide and oxygen concentration in the package to maintain quality. The 10,000cc film was appeared the significantly highest ethylene concentration at $5^{\circ}C$, $11^{\circ}C$, and $24^{\circ}C$, this film had the lowest $O_2$ permeability. Visual quality, firmness, and soluble solids were maintained in 20,000cc films both at $5^{\circ}C$ and $11^{\circ}C$, the 40,000cc film at $24^{\circ}C$. There was no any trend in titratable acidity and vitamin C content of treated packed film types and temperatures at cherry tomatoes packages. Therefore, the appropriate MA condition for $5^{\circ}C$ and $11^{\circ}C$ is $20,000cc/m^2.day.atm$ $O_2$ permeability film; for $24^{\circ}C$ it is $40,000cc/m^2.day.atm$ $O_2$ permeability film because those films extended the storability through the firmness, soluble solids as well as visual quality.