• Environmental Engineering Research
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• 제25권3호
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• pp.290-298
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• 2020

A large residual fraction of aliphatic components of diesel prevails in soil, which has adverse effects on the environment. This study identified the most bio-recalcitrant aliphatic residual fraction of diesel through total petroleum-hydrocarbon fractional analysis. For this, the strain Acinetobacter sp. K-6 was isolated, identified, and characterized and investigated its ability to degrade diesel and n-alkanes (C₁₈, C₂₀, and C₂₂). The removal efficiency was analysed after treatment with bacteria and nutrients in various soil microcosms. The fractional analysis of diesel degradation after treatment with the bacterial strains identified C₁₈-C₂₂ hydrocarbons as the most bio-recalcitrant aliphatic fraction of diesel oil. Acinetobacter sp. K-6 degraded 59.2% of diesel oil and 56.4% of C₁₈-C₂₂ hydrocarbons in the contaminated soil. The degradation efficiency was further improved using a combinatorial approach of biostimulation and bioaugmentation, which resulted in 76.7% and 73.7% higher degradation of diesel oil and C₁₈-C₂₂ hydrocarbons, respectively. The findings of this study suggest that the removal of mid-length, non-volatile hydrocarbons is affected by the population of bio-degraders and the nutrients used in the process of remediation. A combinatorial approach, including biostimulation and bioaugmentation, could be used to effectively remove large quantities of aliphatic hydrocarbons persisting for a longer period in the soil.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.609-614
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• 2013

Extended H$\ddot{u}$ckel tight-binding band structure calculations are used to address the chemical bonding and elastic properties of $Zr_2AC$ (A=Al, Si, P, and S). Elastic properties are interpreted by analyzing the density of states and the crystal orbital overlap population for the respective phases. Our results show that the bulk modulus of these ternary compounds is determined by the strength of Zr-A bonds.

• Asian-Australasian Journal of Animal Sciences
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• 제33권4호
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• pp.539-546
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• 2020

Objective: The Jeju native pig (JNP) found on the Jeju Island of Korea is a unique black pig known for high-quality meat. To investigate the genetic uniqueness of JNP, we analyzed the selection signature of the JNP in comparison to commercial pigs such as Berkshire and Yorkshire pigs. Methods: We surveyed the genetic diversity to identify the genetic stability of the JNP, using the linkage disequilibrium method. A selective sweep of the JNP was performed to identify the selection signatures. To do so, the population differentiation measure, Weir-Cockerham's F_st was utilized. This statistic directly measures the population differentiation at the variant level. Additionally, we investigated the gene ontologies (GOs) and genetic features. Results: Compared to the Berkshire and Yorkshire pigs, the JNP had lower genetic diversity in terms of linkage disequilibrium decays. We summarized the selection signatures of the JNP as GO. In the JNP and Berkshire pigs, the most enriched GO terms were epithelium development and neuron-related. Considering the JNP and Yorkshire pigs, cellular response to oxygen-containing compound and generation of neurons were the most enriched GO. Conclusion: The selection signatures of the JNP were identified through the population differentiation statistic. The genes with possible selection signatures are expected to play a role in JNP's unique pork quality.

• 한국수산과학회지
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• 제56권5호
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• pp.701-707
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• 2023

We investigated Euphausia pacifica population in Korean waters in 2016 By samplings for genetic structur at five stations. Three sampling stations were located in the middle of the water masses which were clustered by temperature and salinity whereas the other stations were at the boundaries of the water masses. We amplified a 566 bp region and compared it with sequences of E. pacifica distributed in other waters. Sequences were classified two clades, and a clade was formed in the station E. Genetic distance of station E was close to E. pacifica present in Bering Sea, while it was distant to E. pacifica present in Yellow Sea near China. In genetic analysis, seven haplotypes were formed. Hap-1 and Hap-2 were shared in all five stations, while Hap-3 was shared in station W and WS. Four independent haplotypes were present in station E. Haplotype and nucleotide diversity were the highest in station E and the lowest in station S. The F_ST distances between station E and other stations were the highest, but distances among other stations were low. As a result, we concluded that E. pacifica, which is distributed in Korean waters, has a genetic population differentiation in the East Sea (station E).

• Carbon letters
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• 제13권3호
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• pp.167-172
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• 2012

Most heavy metals are well-known toxic and carcinogenic agents and when discharged into wastewater represent a serious threat to the human population and the fauna and flora of the receiving water bodies. The present study aims to develop a procedure for Pb (II) removal. This procedure is based on using powdered activated carbon, which was prepared from walnut shells that were generated as plant wastes and modified with potassium carbonate and phosphoric acid as chemical agents. The main parameters, such as effect of pH, effect of sorbent dosage, Pb (II) concentrations, and various contact times influence the sorption process. The experimental results were analyzed by using Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich adsorption models. The kinetic study of Pb (II) on activated carbon from walnut shells was performed based on pseudo- first order and pseudo- second order equations. The data indicate that the adsorption kinetics follow the pseudo- second order rate. The procedure was successfully applied for Pb (II) removal from aqueous solutions.

• Carbon letters
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• 제13권2호
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• pp.115-120
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• 2012

Most heavy metals are well-known toxic and carcinogenic agents and when discharged into wastewater represent a serious threat to the human population and the fauna and flora of the receiving water bodies. The present study aims to develop a procedure for Pb(II) removal. The study was based on using powdered activated carbon, which was prepared from walnut shells generated as plant wastes and modified with potassium carbonate or phosphoric acid as chemical agents. The main parameters, such as effect of pH, effect of sorbent dosage, Pb(II) concentrations, and various contact times influence the sorption process. The experimental results were analyzed by using Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich adsorption models. The kinetic study of Pb(II) on activated carbon from walnut shells was performed based on pseudo-first order and pseudo-second order equations. The data indicate that the adsorption kinetics follow the pseudo-second order rate. The procedure was successfully applied for Pb(II) removal from aqueous solutions.

• 천문학회지
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• 제49권4호
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• pp.145-155
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• 2016

The Sausage radio relic is the arc-like radio structure in the cluster CIZA J2242.8+5301, whose observed properties can be best understood by synchrotron emission from relativistic electrons accelerated at a merger-driven shock. However, there remain a few puzzles that cannot be explained by the shock acceleration model with only in-situ injection. In particular, the Mach number inferred from the observed radio spectral index, M_radio ≈ 4.6, while the Mach number estimated from X-ray observations, M_X−ray ≈ 2.7. In an attempt to resolve such a discrepancy, here we consider the re-acceleration model in which a shock of M_s ≈ 3 sweeps through the intracluster gas with a pre-existing population of relativistic electrons. We find that observed brightness profiles at multi frequencies provide strong constraints on the spectral shape of pre-existing electrons. The models with a power-law momentum spectrum with the slope, s ≈ 4.1, and the cutoff Lorentz factor, γ_e,c ≈ 3−5×10⁴, can reproduce reasonably well the observed spatial profiles of radio fluxes and integrated radio spectrum of the Sausage relic. The possible origins of such relativistic electrons in the intracluster medium remain to be investigated further.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1657-1663
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• 2022

This study uses data from 1970 to 2016 to analyze the effect of nuclear energy use on CO₂ emissions and attempts to validate the EKC hypothesis using the Fourier Autoregressive Distributive Lag model in India for the first time. Because of India's rapidly rising population, the environment is being severely strained. However, with 22 operational nuclear reactors, India boasts tremendous nuclear energy potential to cut down on CO₂ emissions. The EKC is validated in India as the significant coefficients of GDP and GDP.² The short-run estimates also suggest that most environmental externalities are corrected within a year. Given the findings, some policy recommendations abound. The negative statistically significant coefficient of nuclear energy consumption is an indication that nuclear power expansion is essential to achieving clean and sustainable growth as a policy goal. Also, policymakers should enact new environmental laws that support the expansion and responsible use of nuclear energy as it is cleaner than fossil fuels and reduces the cost and over-dependence on oil, which ultimately leads to higher economic growth in the long run. Future research should consider studying the nonlinearities in the nuclear energy-CO₂ emissions nexus as the current study is examined in the linear sense.

• Smart Structures and Systems
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• 제30권4호
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• pp.421-432
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• 2022

Regarding the high significance of correct pan evaporation modeling, this study introduces two novel neuro-metaheuristic approaches to improve the accuracy of prediction for this parameter. Vortex search algorithms (VSA), sunflower optimization (SFO), and stochastic fractal search (SFS) are integrated with a multilayer perceptron neural network to create the VSA-MLPNN, SFO-MLPNN, and SFS-MLPNN hybrids. The climate data of Arcata-Eureka station (operated by the US environmental protection agency) belonging to the years 1986-1989 and the year 1990 are used for training and testing the models, respectively. Trying different configurations revealed that the best performance of the VSA, SFO, and SFS is obtained for the population size of 400, 300, and 100, respectively. The results were compared with a conventionally trained MLPNN to examine the effect of the metaheuristic algorithms. Overall, all four models presented a very reliable simulation. However, the SFS-MLPNN (mean absolute error, MAE = 0.0997 and Pearson correlation coefficient, R_P = 0.9957) was the most accurate model, followed by the VSA-MLPNN (MAE = 0.1058 and R_P = 0.9945), conventional MLPNN (MAE = 0.1062 and R_P = 0.9944), and SFO-MLPNN (MAE = 0.1305 and R_P = 0.9914). The findings indicated that employing the VSA and SFS results in improving the accuracy of the neural network in the prediction of pan evaporation. Hence, the suggested models are recommended for future practical applications.

• 응용통계연구
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• 제34권5호
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• pp.823-835
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• 2021

지역별 인구의 분포에 영향을 미치는 요인의 파악은 국가의 사회, 경제, 문화적 발전 위한 정부의 인구정책 수립에 매우 중요하다. 본 연구에서는 2019년 인구주택 총조사 자료를 기반으로 대한민국 국토를 서울, 대도시, 기타지역의 세 지역으로 나누어 각 지역에서 소지역의 인구 크기에 영향을 미치는 요인들을 살펴 보았다. 인구 자료의 특징은 매우 비대칭적이며 이분산성을 가지므로 조건부 평균에 초점을 맞추는 일반적인 회귀모형 대신 분포에 대한 가정이 필요하지 않은 분위회귀모형을 사용하여 인구의 크기에 따라 변화하는 각 요인의 세부적인 영향을 살펴보았다. 분석결과 서울, 대도시, 기타지역에 따라 그리고 같은 지역 내에서도 세부 지역의 인구크기에 따라 요인의 영향이 매우 달라짐을 확인하였다. 이 결과들은 인구관련 변수들이 지역 마다 매우 이질적인 성질을 가지고 있으며 따라서 획일적인 인구정책이 아닌 지역 특성에 맞는 맞춤형 인구정책을 수립해야 할 필요성을 시사한다.