• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.2
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• pp.95-104
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• 2019

This study is aimed to take a stock assessment of blackthroat seaperch Doederleinia seaperch regarding the fishing effort of large-powered Danish Seine Fishery and Southwest Sea Danish Seine Fishery. For the assessment, the state-space model was implemented and the standardized catch per unit effort (CPUE) of large powered Danish Seine Fishery and Southwest Sea Danish Seine Fishery which is necessary for the model was estimated with generalized linear model (GLM). The model was adequate for stock assessment because its r-square value was 0.99 and root mean square error (RMSE) value was 0.003. According to the model with 95% confidence interval, maximum sustainable yield (MSY) of Blackthroat seaperch is from 2,634 to 6,765 ton and carrying capacity (K) is between 33,180 and 62,820. Also, the catchability coefficient (q) is between 2.14E-06 and 3.95E-06 and intrinsic growth rate (r) is between 0.31 and 0.72.

• Membrane and Water Treatment
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• v.15 no.2
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• pp.67-78
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• 2024

In this study, a nickel hexacyanoferrate and manganese dioxide-polyacrylonitrile (NM-PAN) composite was synthesized and used for the sorptive removal of Co²⁺, Sr²⁺, and Cs⁺ Cs⁺ in radioactive laundry wastewater. Single- and multi-solute competitive sorptions onto NM-PAN were investigated. The Freundlich (Fr), Langmuir (Lang), Kargi-Ozmıhci (K-O), Koble-Corrigan (K-C), and Langmuir-Freundlich (Lang-Fr) models satisfactorily predicted all the single sorption data. The sorption isotherms were nonlinearly favorable (Freundlich coefficient, N_F = 0.385-0.426). Cs⁺ has the highest maximum sorption capacity (q_mL = 0.855 mmol g^-1) for NM-PAN compared to Co²⁺ and Sr²⁺, wherein the primary mechanism was the physical process (mainly ion-exchange). The competition between the metal ions in the binary and ternary systems reduced the respective sorption capacities. Binary and ternary sorption models, such as the ideal adsorbed solution theory (IAST) model coupled with single sorption models of IAST-Fr, IAST-K-O, IAST-K-C and IAST-Lang-Fr, were fitted to the experimental data; among these, the IAST-Freundlich model showed the most satisfactory prediction for the binary and ternary systems. The presence of cationic surfactants highly affected the sorption on NM-PAN due to the increase in distribution coefficients (K_d) of Co²⁺ and Cs⁺.

• Nuclear Engineering and Technology
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• v.56 no.5
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• pp.1830-1835
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• 2024

The current study aims to study the impacts of the substitution of magnesium with nickel concentrations on physical and γ-ray shielding capacity of magnesium alloys. The density of the magnesium alloys under study is varied from 3.677 g/cm³ to 5.652 g/cm³, with raising the nickel content from 26.7 wt% to 54.8 wt% and reducing the magnesium concentration from 72.6 wt% to 44.2 wt%, respectively. Additionally, the examination of the γ-ray shielding capacity using the Monte Carlo simulation code shows that the substitution of magnesium by nickel content in the magnesium alloys was associated with an enhancement in the γ-ray shielding capacity, where the linear attenuation coefficient for the studied alloys was enhanced by 53.22 %, 52.45 %, and 52.52 % at γ-ray energies of 0.662 MeV, 1.252 MeV, and 1.408 MeV, respectively, with raising the nickel concentration from 26.7 wt% to 54.8 wt%. Simultaneously, the half-value thickness for magnesium alloys was reduced from 2.47 cm to 1.62 cm (at gamma ray energy of 0.662 MeV), from 3.39 cm to 2.22 cm (at gamma ray energy of 1.252 MeV), and from 3.60 cm to 2.36 cm (at gamma ray energy of 1.408 MeV), raising the nickel concentration from 26.7 wt % to 54.8 wt%, respectively. The study shows that the substitution of magnesium for nickel greatly enhanced the radiation shielding capacity of the magnesium alloys.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.12
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• pp.868-873
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• 2011

Oxygen transfer rate generally determines the performance of an aerobic wastewater treatment process that treats high strength wastewater such as food wastewater, animal wastewater and landfill leachate. In this paper, OUR and $K_L{\cdot}a$ were evaluated by using Jet Loop Reactor (JLR) according to the concentration of a mixed liquor volatile suspended solid (MLVSS), oxygen (air) flow rate and energy input as the variable of the operating conditions. Also, a nonlinear regression model was proposed by the statistical methods with the calculated $K_L{\cdot}a$. As a results, in case of applying the high strength wastewater which has to maintain high MLVSS, the energy input and the air flow rate are major parameters oxygen transfer rate in JLR. Finally, the final nonlinear regression model had been developed as a function of E/V, $Q_g$, and ${\mu}_c$.

• Wind and Structures
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• v.27 no.1
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• pp.11-27
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• 2018

The straight-cone steel cooling tower is a novel type of structure, which has a distinct aerodynamic distribution on the internal surface of the tower cylinder compared with conventional hyperbolic concrete cooling towers. Especially in the extreme weather conditions of strong wind and heavy rain, heavy rain also has a direct impact on aerodynamic force on the internal surface and changes the turbulence effect of pulsating wind, but existing studies mainly focus on the impact effect brought by wind-driven rain to structure surface. In addition, for the indirect air cooled cooling tower, different additional ventilation rate of shutters produces a considerable interference to air movement inside the tower and also to the action mechanism of loads. To solve the problem, a straight-cone steel cooling towerstanding 189 m high and currently being constructed is taken as the research object in this study. The algorithm for two-way coupling between wind and rain is adopted. Simulation of wind field and raindrops is performed with continuous phase and discrete phase models, respectively, under the general principles of computational fluid dynamics (CFD). Firstly, the rule of influence of 9 combinations of wind sped and rainfall intensity on flow field mechanism, the volume of wind-driven rain, additional action force of raindrops and equivalent internal pressure coefficient of the tower cylinder is analyzed. On this basis, the internal pressures of the cooling tower under the most unfavorable working condition are compared between four ventilation rates of shutters (0%, 15%, 30% and 100%). The results show that the 3D effect of equivalent internal pressure coefficient is the most significant when considering two-way coupling between wind and rain. Additional load imposed by raindrops on the internal surface of the tower accounts for an extremely small proportion of total wind load, the maximum being only 0.245%. This occurs under the combination of 20 m/s wind velocity and 200 mm/h rainfall intensity. Ventilation rate of shutters not only changes the air movement inside the tower, but also affects the accumulated amount and distribution of raindrops on the internal surface.

• Journal of the Korea Concrete Institute
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• v.24 no.2
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• pp.137-145
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• 2012

Strength model for blasted furnace slag mortar blended with sodium was investigated in this study. The main parameters of AAS (alkali activated slag) mortar were dosage of alkali activator, water to binder ratio (W/B), and aggregate to binder ratio (A/B). For evaluating the property related to the dosage of alkali activator, sodium carbonate ($Na_2CO_3$) of 4~8% was added to 4% dosage of sodium hydroxide (NaOH). W/B and A/B was varied 0.45~0.60 and 2.05~2.85, respectively. An alkali quality coefficient combining the amounts of main compositions of source materials and sodium oxide ($Na_2O$) in sodium hydroxide and sodium carbonate is proposed to assess the compressive strength of alkali activated mortars. Test results clearly showed that the compressive strength development of alkali-activated mortars were significantly dependent on the proposed alkali quality coefficient. Compressive strength development of AAS mortars were also estimated using the formula specified in the previous study, which was calibrated using the collected database. Predictions from the simplified equations showed good agreements with the test results.

• Korean Journal of Environment and Ecology
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• v.34 no.2
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• pp.157-169
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• 2020

The purpose of this study is to investigate the ecological characteristics and vegetation structures of Eurya japonica in Busan. As a result of the TWINSPAN and DCA analysis, 89 plots of 100㎡ each were divided into 3 communities: Quercus serrata-Pinus densiflora-E. japonica community, Pinus thunbergii-E. japonica community, and P. thunbergii-Camellia japonica community. Community I consisted of the Quercus serrata-Pinus densiflora-E. japonica which was mainly located in the high altitude inland. While Q. serrata and P. densiflora competed in the tree layer, the dominant species of the understory layer was E. japonica. Since Carpinus tschonoskii, one of the climax species, was distributed evenly from shrub to tree layers, it was likely that deciduous oak trees or Carpinus tschonoskii would become dominant species in community I. In community I, E. japonica was found in higher altitude than the other evergreen broad-leaved tree and was expected to maintain their tree vigor even if the vegetation structure is converted into the deciduous forest. Community II, the P. thunbergii-E. japonica community, was predicted to maintain its tree vigor unless there were unexpected disturbance factors. Community III, consisting of P. thunbergii-C. japonica and located in Dongbaek Island, was under artificial management. In community III, P. thunbergii was the only species in the tree layer, while C. japonica was predominant in the understory layer. E. japonica and various evergreen broad-leaved tree species were present in the understory layer and shrub layer, which were unmanaged areas. Therefore, it is expected that unless C. japonica is continuously managed, E. japonica is likely to become the dominant species. There were also various evergreen broad-leaved species, such as Machilus thunbergii and Pittosporum tobira, present in the shrub layer. If the temperature continues to rise, the habitat is expected to become evergreen broad-leaved forests in the future as P. thunbergii community declines. The result of Pearson's correlation coefficient analysis of E. japonica and species appearing in 89 plots showed that 9 species were had a statistically significant relationship (p<0.05). Four species, including P. tobira and Q. dentata, had a positive correlation. Five species had a negative correlation, and C. japonica, which had the same ecological position as E. japonica, showed the most negative correlation at -0.384.

• Journal of Biosystems Engineering
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• v.29 no.3
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• pp.267-274
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• 2004

Using geo-statistical method, yield data of different fields were analyzed to examine their field variability according to examining year, analysis method. Semivariogram and Kriged maps of geo-statistical analysis were used to examine their spatial dependence within a filed. The results obtained were as follows. 1) Descriptive statistical results of the yield showed that the yield and the difference of yield ranged from 100 to 946kg/10a and from 272 to 653kg/10a, respectively within a field. The coefficient of variation also ranged from 5.9 to 22.4 %. 2) More than 90% of yield data were placed between 350 to 850kg/10a. e results indicated that the gram mass flow sensor should have the measuring range from 0.34 to 0.82kg/s considering the yields when 4 rows head-feeding combine with 0.8 m/s of working speed was utilized. 3) A high spatial dependence was found within paddy field. The Q values ranged from 0.20 to 0.97, and the range of spatial dependence was from 6.9 to 53.3m. From this result, the rational sampling interval for yield investigation was estimated 6.9m. 4) Yields within a field between observation years showed considerable variability even if the field was evenly cultivated and managed. To apply precision agriculture in a paddy field, the field test should be continued to build a solid data-base including meteorological data, blight damage and insect damage.

• Journal of Korea Water Resources Association
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• v.51 no.10
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• pp.905-916
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• 2018

The purpose of this study is to evaluate the climate change impact on watershed hydrology and flow duration in Geum River basin ($9,645.5km^2$) especially by extreme scenarios. The rainfall related extreme index, STARDEX (STAtistical and Regional dynamical Downscaling of EXtremes) was adopted to select the future extreme scenario from the 10 GCMs with RCP 8.5 scenarios by four projection periods (Historical: 1975~2005, 2020s: 2011~2040, 2050s: 2041~2070, 2080s: 2071~2100). As a result, the 5 scenarios of wet (CESM1-BGC and HadGEM2-ES), normal (MPI-ESM-MR), and dry (INM-CM4 and FGOALS-s2) were selected and applied to SWAT (Soil and Water Assessment Tool) hydrological model. The wet scenarios showed big differences comparing with the normal scenario in 2080s period. The 2080s evapotranspiration (ET) of wet scenarios varied from -3.2 to +3.1 mm, the 2080s total runoff (TR) varied from +5.5 to +128.4 mm. The dry scenarios showed big differences comparing with the normal scenario in 2020s period. The 2020s ET for dry scenarios varied from -16.8 to -13.3 mm and the TR varied from -264.0 to -132.3 mm respectively. For the flow duration change, the CFR (coefficient of flow regime, Q10/Q355) was altered from +4.2 to +10.5 for 2080s wet scenarios and from +1.7 to +2.6 for 2020s dry scenarios. As a result of the flow duration analysis according to the change of the hydrological factors of the Geum River basin applying the extreme climate change scenario, INM-CM4 showed suitable scenario to show extreme dry condition and FGOALS-s2 showed suitable scenario for the analysis of the drought condition with large flow duration variability. HadGEM2-ES was evaluated as a scenario that can be used for maximum flow analysis because the flow duration variability was small and CESM1-BGC was evaluated as a scenario that can be applied to the case of extreme flood analysis with large flow duration variability.

• The Korean Journal of Pesticide Science
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• v.8 no.3
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• pp.151-161
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• 2004

Three dimensional quantitative structure-activity relationships (3D-QSAR) studies for the protox inhibition activities against root and shoot of rice plant (Orysa sativa L.) and barnyardgrass (Echinochloa crus-galli) by a series of new A=3,4,5,6-tetrahydrophthalimino, B=3-chloro-4,5,6,7-tetrahydro-2H-indazolyl and C=3,4-dimethylmaleimino group, and R-group substituted on the phenyl ring in 1-(5-methyl-3-phenylisoxazolin-5-yl)methoxy-2chloro-4-fluorobenzene derivatives were performed using comparative molecular field analyses (CoMFA) methodology with Gasteiger-Huckel charge. Four CoMFA models for the protox inhibition activities against root and shoot of the two plants were generated using 46 molecules as training set and the predictive ability of the each models was evaluated against a test set of 8 molecules. And the statistical results of these models with combination (SIH) of standard field, indicator field and H-bond field showed the best predictability of the protox inhibition activities based on the cross-validated value $r^2_{cv.}$ $(q^2=0.635\sim0.924)$, conventional coefficient $(r^2_{ncv.}=0.928\sim0.977)$ and PRESS value $(0.091\sim0.156)$, respectively. The activities exhibited a strong correlation with steric $(74.3\sim87.4%)$, electrostatic $(10.10\sim18.5%)$ and hydrophobic $(1.10\sim8.30%)$ factors of the molecules. The steric feature of molecule may be an important factor for the activities. We founded that an novel selective and higher protox inhibitors between the two plants may be designed by modification of X-subsitutents for barnyardgrass based upon the results obtained from CoMFA analyses.