• Analytical Science and Technology
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• v.20 no.1
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• pp.25-32
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• 2007

The measurement methods for total nitrogen in wastewater containing a high concentration of nitrogen were evaluated. (1) The UV spectrophotometry, (2) reduction-distillation Kjeldahl, (3) total Kjeldahl nitrogen, and (4) ion chromatography methods were applied. The experimental procedure of the UV spectrophotometric method was simple, but it produced large errors deriving from the dilution of samples and calibration standards. While, the reduction-distillation Kjeldahl method didn't need dilution, but the amount of Devarda's alloy and NaOH lead to large errors up to 50 mg/L. The levels of total nitrogen measured by each method were as follows: reduction-distillation Kjeldahl ($568.6{\pm}38.7mg/L$) > UV spectrophotometry ($527.3{\pm}9.6mg/L$) > total Kjeldahl nitrogen method ($494.7{\pm}21.4mg/L$) > ion chromatography method ($417.9{\pm}7.3mg/L$). Therefore, the reduction-distillation Kjeldahl method is preferred for wastewater with the high concentration of nitrogen. Optimal conditions for each experimental procedure, however, are needed to be confirmed, and the Standard Operation Procedure (SOP) for total nitrogen is required for reliable measurements.

• Explosives and Blasting
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• v.41 no.3
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• pp.62-72
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• 2023

The aging of plant structures due to industrialization in the 1970s has increased the demand for blast demolition. While blasting can reduce exposure to environmental pollution by shortening the demolition period, improper blasting design and construction plans pose significant safety risks. Thus, it is vital to consider optimal blasting demolition conditions and other factors through collapse behavior simulation. This study utilizes a 3-D combined finite-discrete element method (FDEM) code-based 3-D DFPA to simulate the collapse of a chimney structure in a thermal power plant in Seocheon, South Korea. The collapse behavior from the numerical simulation is compared to the actual structure collapse, and the numerical simulation result presents good agreement with the actual building demolition. Additionally, various numerical simulations have been conducted on the chimney models to analyze the impact of the duct size in the pre-weakening area. The no-duct, duct, and double-area duct models were compared in terms of crack pattern and history of Z-axis displacement. The findings show that the elapse-time for demolition decreases as the area of the duct increases, causing collapse to occur quickly by increasing the load-bearing area.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.2
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• pp.118-126
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• 2009

Benthic diatoms are very important primary producers in understanding estuary ecosystems and their productions are largely varied by their photo-physiological characteristics. The short-term effects of increased temperature on the photosynthetic and photo-physiological characteristics of cultured different species of benthic diatoms (Navicula sp., Nitzschia sp., Cylindrotheca closterium, and Pleurosigma elongatum) were investigated by measuring their PSII-fluorescence kinetics using a Diving-PAM. Photosynthesis versus irradiance curves were measured every two hours at six different temperatures (10, 15, 20, 25, 30, and $35^{\circ}C$) for twenty-four hour. The effective quantum yield of PSII ($\Phi_{PSII}$) for most of the species showed a decreasing trend with increased temperature. The relative maximum electron transport rate (rETRmax) was significantly increased up to the optimum temperature level and then sharply decreased. Relative to the values of other parameters, the maximum light use coefficient ($\alpha$) was not substantially changed at lower temperature levels (<$30^{\circ}C$) but significantly decreased only at higher temperatures (30 and $35^{\circ}C$). The light saturation coefficient ($E_K$) mirrored the rETRmax temperature response. In regards to the temperature acclimation abilities of the four species with time, Navicula sp. and C. closterium acclimated to short-term changes in temperature through their photo-physiological adjustments.

• Journal of Life Science
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• v.30 no.2
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• pp.156-161
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• 2020

Since industrialization, the production and utilization of various chemicals has contributed to improving the quality of our lives, but the subsequent discharge of massive waste is inevitable, and environmental pollution is becoming more serious every day. Exposure to chemicals as a result of environmental pollution is having a negative effect on human health and the ecosystem, and cleaning up the polluted environment that can affect our lives is a very important issue. Toxic aromatic compounds have been detected frequently in soil, groundwater, and wastewater because of the extensive use of oil products, and phenol, which is used to produce synthetic resins, textiles, and dyes, is one of the major pollutants, along with insecticides and preservatives. Phenol can cause dyspnea, headache, vomiting, mutation, and carcinogenesis. Phenol-degrading bacterium DWB-1-8 was isolated from the activated sludge of textile wastewater; this strain was identified as Comamonas testosteroni by 16S rRNA gene sequencing. The optimal culture conditions for the cell growth and degradation of phenol were 0.7% K₂HPO₄, 0.6% NaH₂PO₄, 0.1% NH₄NO₃, 0.015% MgSO₄·7H₂O, 0.001% FeSO₄·7H₂O, an initial pH of 7, and a temperature of 30℃. The strain was also able to grow by using other toxic compounds, such as benzene, toluene, or xylene (BTX), as the sole source of carbon.

• Ecology and Resilient Infrastructure
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• v.8 no.4
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• pp.223-232
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• 2021

In general, stormwater flows to the road surface, especially in urban areas, and it is discharged through the drainage grate inlets on roads. The appropriate evaluation of the road drainage capacity is essential not only in the design of roads and inlets but also in the design of sewer systems. However, the method of road surface flow analysis that reflects the topographical and hydraulic conditions might not be fully developed. Therefore, the enhanced method of road surface flow analysis should be presented by investigating the existing analysis method such as the flow analysis module (uniform; varied) and the flow travel time (critical; fixed). In this study, the algorithm based on varied and uniform flow analysis was developed to analyze the flow pattern of road surface. The numerical analysis applied the uniform and varied flow analysis module and travel time as parameters were conducted to estimate the characteristics of rainfall-runoff in various road conditions using the developed algorithm. The width of the road (two-lane (6 m)) and the slope of the road (longitudinal slope of road 1 - 10%, transverse slope of road 2%, and transverse slope of gutter 2 - 10%) was considered. In addition, the flow of the road surface is collected from the gutter along the road slope and drained through the gutter in the downstream part, and the width of the gutter was selected to be 0.5 m. The simulation results were revealed that the runoff characteristics were affected by the road slope conditions, and it was found that the varied flow analysis module adequately reflected the gutter flow which is changed along the downstream caused by collecting of road surface flow at the gutter. The varied flow analysis module simulated 11.80% longer flow travel time on average (max. 23.66%) and 4.73% larger total road surface discharge on average (max. 9.50%) than the uniform flow analysis module. In order to accurately estimate the amount of runoff from the road, it was appropriate to perform flow analysis by applying the critical duration and the varied flow analysis module. The developed algorithm was expected to be able to be used in the design of road drainage because it was accurately simulated the runoff characteristics on the road surface.

• Korean Journal of Environmental Agriculture
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• v.25 no.1
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• pp.64-70
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• 2006

This study was conducted to investigate the concentration of fertigation for optimum yield and soil management of tomato cultivation in soils with different Electrical conductivity (EC) level under PE film house. The EC levels of soil were adjusted to 1.4, 3.0 and 5.4 dS/m and fertigation concentrations were supplied with 0.0 (groundwater), 1.0, 2.0 and 3.0 dS/m, respectively. When the concentration of fertigation was supplied over 3.0 dS/m to soil with EC 1.4 dS/m, the concentrations of $NO_3-N,\;avail.-P_2O_5$, and exchangeable K in soil were increased after the experiment. When fertigation concentration was supplied over 2.0 and 1.0 ds/m to soil with EC 3.0 and 5.4 dS/m respectively, the nutrient were also accumulated in the soil. Thus, the optimum concentrations of fertigation for optimum yield and soil management for tomato cultivation were recommended $1.0{\sim}2.0dS/m$, 1.0 dS/m and ground water (0.0 dS/m) to soils with EC 1.4, 3.0 and 5.4 dS/m, respectively. The fruit weight marketability and marketable yield of tomato were not significant among the treatments at 5% level by LSD. The concentrations of T-N, $P_2O_5\;and\;K_2O$ in tomato leaf were increased with increasing of fertigation concentration whereas the concentrations of CaO and MgO decreased with increasing of fertigation concentration.

• Korean Journal of Plant Resources
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• v.15 no.3
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• pp.237-242
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• 2002

Loaves, stems, cotyledons, and roots of Hovenia dulcis Thunb grown in test tube were cultured on media containing different concentrations of single or combined growth regulators. In MS media containing 2mg/ι BA, the shoot formation rate was 95.5% and it was the highest frequency of shoot formation. MS media showed most efficiency in the shoot formation at 0.01mg/ι TDZ for the callus formation, but the color of callus changed to brown at a higher concentration of TDZ. Callus formation was 89.% at 0.5mg/ 2.4-D, but IAA, IBA, and NAA were not effective on the formation of callus. Calli were formed only on wound area when IAA, IBA, and NAA were added into MS media. Combined growth regulators (BA + auxin) were more effective in roots and nodes than leaves and cotyledons on the formation of shoot. More than 97％ of shoot formation was obtained on MS media containing BA and auxin. For the production of multiple shoot, nodes of Hovenia dulcis were used and effect of growth regulators on the formation of multiple shoot was evaluated on MS media. Highest shoots (5.3) of Hovenia dulcis were induced on MS media supplied with 0.1mg/ι BA and 0.1mg/ι NAA, and an average of 6.4 shoots per explant were obtained in 1/2 MS media containing same concentration and growth regulators. An average of 7 shoots per explant after 4 weeks of culture from nodes of Hovenia dulcis was produced on a woody plant medium(WPM) containing 0.1mg/ι BA and 0.1mg/ι NAA. Shoot length was 6.0 cm in average.

• Journal of Bio-Environment Control
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• v.21 no.2
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• pp.102-107
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• 2012

This study was carried out to investigate the optimum soil environmental conditions of ten contents on production of high quality fruit in 'Hongro' apple. The soil and fruit characteristics were analyzed at total 60 orchards in major apple producing areas such as Chungju, Moonkyeung, Yeongju, Andong, Yeosan and Yeongcheon (10 orchards an area). The soil environmental factors affected fruit weight were the highest relative contribution in saturated hydraulic conductivity of 33.3%. The cation was 24.6%, the bulk density, soil texture and solid phase were also high as relative contribution. The fruit weight was influenced by soil physical properties more than soil chemical properties. The soil environmental factors affected sugar content were highest soil texture of 21.9%, and the CEC and bulk density were low as relative contribution. The fruit coloring was the highest relative contribution in phosphate of 55.9%. While saturated hydraulic conductivity and organic matter content were low. The coloring was influenced by soil chemical properties more than soil physical properties. Fruit coloring was high influenced over 70% by soil physical properties. Finally, relative contribution on fruit quality related with sugar content, fruit weight, and coloring were high influenced by cultivation layer depth of 25.8%, soil texture 22.2%, and soil pH of 21.0% but bulk density and solid phase were low relative contribution. The fruit growth and soil chemical properties in 'Hongro' apple were very closely related. Therefore, orchard soil management to produce high quality fruit was very importance drainage management and organic matter application. We concluded that scientific soil management is possible by quanlifiable of soil management factors.

• Journal of Climate Change Research
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• v.1 no.2
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• pp.121-131
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• 2010

This study was carried out to evaluate spatial variations in rice production areas by simulating rice growth and yield with CERES-Rice growth model under GCM $2{\times}CO_2$ climate change scenarios. A modified window version(v4.0) of CERES-Rice was used to simulate the growth and development of three varieties, representing early, medium, and late maturity classes. Simulated growth and yield data of the three cultivars under the climate for 1971 to 2000 was set as a reference. Compared with the current normal(1971 to 2000), heading period from transplanting to heading date decreased by 7~8 days for the climate in $2^{\circ}C$ increase over normal, and 16~18 days for the climate in UKMO with all maturity classes, while change of ripening period from heading to harvesting date was different with maturity classes. That is, physical maturity was shortened by 1~3 days for early maturity class and 14~18 days for late maturity class under different climate change scenarios. Rice yield was in general reduced by 4.5%, 8.2%, 9.9%, and 14.9% under the climate in $2^{\circ}C$, $3^{\circ}C$, $4^{\circ}C$, and about $5^{\circ}C$ increase, respectively. The yield reduction was due to increased high temperature-induced spikelet sterility and decreased growth period. The results show that predicted climate changes are expected to bring negative effects in rice production in Korea. So, it is required for introduction of new agricultural technologies to adapt to climate change, which are, for example, developing new cultivars, alternations of planting dates and management practices, and introducing irrigation systems, etc.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.9
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• pp.955-960
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• 2008

We investigated and estimated at the characteristics of decomposition and mineralization of benomyl using a design of experiment(DOE) based on the general factorial design in an E-beam process, and also the main factors(variables) with benomyl concentration(X$_1$) and E-beam irradiation(X$_2$) which consisted of 5 levels in each factor was set up to estimate the prediction model and the optimization conditions. At frist, the benomyl in all treatment combinations except 17 and 18 trials was almost degraded and the difference in the decomposition of benomyl in the 3 blocks was not significant(p > 0.05, one-way ANOVA). However, the % of benomyl mineralization was 46%(block 1), 36.7%(block 2) and 22%(block 3) and showed the significant difference of the % that between each block(p < 0.05). The linear regression equations of benomyl mineralization in each block were also estimated as followed; block 1(Y$_1$ = 0.024X$_1$ + 34.1(R$^2$ = 0.929)), block 2(Y$_2$ = 0.026X$_2$ + 23.1(R$^2$ = 0.976)) and block 3(Y$_3$ = 0.034X$_3$ + 6.2(R$^2$ = 0.98)). The normality of benomyl mineralization obtained from Anderson-Darling test in all treatment conditions was satisfied(p > 0.05). The results of prediction model and optimization point using the canonical analysis in order to obtain the optimal operation conditions were Y = 39.96 - 9.36X$_1$ + 0.03X$_2$ - 10.67X$_1{^2}$ - 0.001X$_2{^2}$ + 0.011X$_1$X$_2$(R$^2$ = 96.3%, Adjusted R$^2$ = 94.8%) and 57.3% at 0.55 mg/L and 950 Gy, respectively. A Microtox test using V. fischeri showed that the toxicity, expressed as the inhibition(%), was reduced almost completely after an E-beam irradiation, whereas the inhibition(%) for 0.5 mg/L, 1 mg/L and 1.5 mg/L was 10.25%, 20.14% and 26.2% in the initial reactions in the absence of an E-beam illumination.