• Geomechanics and Engineering
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• v.33 no.3
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• pp.317-326
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• 2023

Accurately measuring the hydraulic conductivity of dredged slurry (HCODS) is a difficult task and usually requires highly developed experimental techniques. To resolve such problem, this paper presents a novel laboratory method, where a double drainage sedimentation test (DDST) is proposed to generate a downward seepage after the end of primary consolidation (EOP). Based on the established stress equilibrium equations, it is figured out that the determination of local hydraulic gradients requires the effective stress distribution to be measured. Accordingly, an additional single drainage sedimentation test (SDST) with the same initial water content is performed in the novel laboratory method, which can be utilized to establish the relationship between effective stress and water content for investigated slurry. Thus, HCODS can be determined via a pair of SDST and DDST, with the water contents after the EOP measured. The corresponding calculation procedure is given in details. With a simply-designed settling column, the hydraulic conductivity tests were performed on three types of dredged slurry. The results demonstrated the effectiveness of the novel laboratory method in measuring HCODS.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.56.2-56.2
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• 2021

Constraining the structure and thus the fate of giant molecular clouds (GMCs), the primary sites of star formation in galaxies, is crucial to understand the evolution of galaxies themselves. Exploiting the unprecedented sensitivity and angular resolution of the Atacama Large Millimeter/sub-millimeter Array (ALMA), we have measured the spatially-resolved (~ 20 pc resolution) properties of the GMCs in two nearby late-type galaxies, NGC 5806 (SAB(s)b) and NGC 6753 ((R)SA(r)b), as part of the WISDOM project. Although these results are preliminary, we identified ~ 200 resolved GMCs in NGC 5806 within a radius of 500 pc, most within a nuclear ring structure, and ~ 400 resolved GMCs in NGC 6753 within a radius of 2 kpc, most within a flocculent spiral structure. The GMCs of NGC 5806 have similar sizes but slightly higher linewidths than clouds in the Milky Way disc. Because the GMCs also have higher surface densities, the calculated cloud Virial parameters are nevertheless about unity, suggesting that the GMCs of NGC 5806 are in gravitational equilibrium and thus long lived. This is contrary to other WISDOM results on earlier-type galaxies, where large cloud linewidths are likely due to shear associated with the local (circular) orbital motions (rather than the clouds' self-gravity), and the clouds are either marginally or not gravitationally bound. These results support the notion that spheroids alter the dynamical states of clouds (morphological quenching), that are otherwise (i.e. in galaxy discs) fairly homogenous and similar to those of the Milky Way.

• Korea Trade Review
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• v.47 no.1
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• pp.115-130
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• 2022

In this study, I focus on analyzing how the effects of implementing ETS are different depending on whether Korean ETS linking with carbon markets in other countries. The global computable general equilibrium (CGE) model built in this study analyzes the chages in the production and trade of industrial sectors according to the international linkage of ETS compared to the reference scenario of emissions reduction targets and implementation of ETS. From the analysis of internatioanl linkage of carbon markets scenarios, Annex B countries-South Korea carbon market linkage with individual ETS in China worse the economic outcomes in South Korea the most. This means South Korea lose the international competitiveness compared to China in this scenario. On the other hand, Annex B-China carbon market linkage with Korean individual ETS implementation reduce the decreases in production and trading. The most effective way is to join a global emissions trading market with China. The results are consistent in most industries of South Korea. These results are caused by that the supply of emission allowance is increased and the price of emissions allowances is dropped by China's participation to the carbon market, which can be understood to reduce the carbon reduction cost for industrial sectors. In addition, it can be also concluded that the determinant of the negative impact of ETS on changes in production and trade is more sensitive to the price of emissions allowances than to the characteristics of production and trade structure.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.4
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• pp.452-458
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• 1997

Seed characteristics such as seed size, seed shape and cotyledon color are important in relation to processing and cooking of soybean. Seed shape, water absorption rate, and alkali digestibility were evaluated for 28 local black soybean collections. Water uptake rate was low in small seed size at low temperature(5, 2$0^{\circ}C$). However, higher water absorption rate was observed at high temperature(40, 6$0^{\circ}C$) regardless of seed size. When seeds soaked up water, it reached to water absorption equilibrium after 10 hrs below 2$0^{\circ}C$, within 10 hrs at 4$0^{\circ}C$, and around 4 hrs at 6$0^{\circ}C$, respectively. Significant positive correlations were observed between 100 seed weight and length, width and thickness of seed, respectively. Alkali digestibility value(ADV) was higher in large seed group than in small seed group. Among seed characteristics, significant positive correlation was shown between ADV and 100 seed weight, length, width, thickness and hilum length of seed, respectively. Soybean seed with green cotyledon showed higher ADV than that with yellow cotyledon.

• Journal of the Korean Society of Groundwater Environment
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• v.2 no.1
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• pp.22-29
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• 1995

Mobile bacterial particles can act as carriers and enhance the transport of hydrophobic contaminants in ground water by reducing retardation effects. Because of their colloidal size and favorable surface conditions, bacteria can act as efficient contaminant carriers. When such carriers exist in a porous medium, the system can be thought of as three phases: an aqueous phase, a carrier phase, and a stationary solid matrix phase. Contaminant can be present in either or all of these phases. In this study, a mathematical model based on mass balances is developed to describe the transport and fate of biodegradable contaminant in a porous medium. Bacterial mass transfer mechanism between aqueous and solid matrix phases, and contaminant mass transfer between aqueous and bacterial phases are represented by kinetic models. Governing equations are non-dimensionalized and solved to analyze the bacteria facilitated contaminant transport. The numerical results of the facilitation effect match favorably with experimental data reported in the literature. Results show that the contaminant transport can be described by local equilibrium assumption when Damkohler numbers are larger than 10. Significant sensitivities to model parameters, particularly bacterial growth rate and influent bacterial concentration, were discovered.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.395-409
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• 2011

The objective of this study is to develop an accurate and robust two-dimensional finite element method for turbulence simulation in open channels. The model is based on Streamline Upwind/Petrov-Galerkin finite element method and Boussinesq's eddy viscosity theory. The method developed in the study is depth-averaged mixing length model which assumes anisotropic and local equilibrium state of turbulence. The model calibration and validation were performed by comparing with analytical solutions and observed data. Several numerical simulations were carried out, which examined the performance of the turbulence model for the purpose of sensitivity analysis. The uniform channels that appear horizontal flow and vertical flow were carried out. The model was also applied to the Han river was in for the applicability test. The results were compared with the observed data. The suggested model displayed reasonable flow distribution compare to the observed data in natural river flow. As a result of this study, the two-dimensional finite element model provides a reliable results for flow distribution based on the turbulence simulation in open channels.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.6
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• pp.530-539
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• 2013

In large vessels, proper water level must be maintained with a balance for right and left equilibrium by absorbing or draining sea water in ballast water tank. However, this ship's ballast-water can be drained marine organisms to local sea area by world trade and this can be a source of ecological disturb. In order to solve these problems, marine organisms must be removed in accordance with the international covenant for the emission of microorganisms. By this reason, the seawater electrolysis rectifier of low-voltage high-current rectifiers with excellent ability for microbial treatment is required. In this paper, PSFB converter will be discussed for the seawater electrolysis rectifier. Furthermore, a new output control method with the power limit operation under the limited maximum voltage condition is proposed for this rectifier. The simulation for the proposed current control method for PSFB Converter is shown using MATLAB/SIMULINK. Finally the usefulness of the proposed control method is presented by the experimental results.

• Journal of Engineering Education Research
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• v.1 no.1
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• pp.43-56
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• 1998

This thesis examined the main revolution trend of Chinese engineering education system which is closely related to the demand of the industrial world. The reasons for which China tried to revolutionize engineering education were as follows ; firstly, the lack of high-qualified and professionalized man power in the industrial world. Secondly, the rupture in the age structure and thirdly, graduate students' insufficient ability to adapt to the industrial companies. These situation had been influenced by professional education after the fashion of the Soviet Union and the Cultural Revolution. Thus, since 1980s, government have extended man power supply through various ways and maintained equilibrium between supply and demand within the industrial world. Also, government began to retrian the existing engineers, magnify the regular number in college students of science and engineering and treat an experienced man favorably in graduate schools. The State Education Commission leaded in searching for the ways to train engineers and testing the master of engineering training system. As an essay at reform, many attempts will be tried ; bringing-up excellent students, the system of multi-degrees, field work, bachelor-master integration management, the system of master and doctor by thesis, strengthening educational-industrial cooperation, experimental school, adult school, and local school. Until 21c to come, this trend will be accelerated on.

• Steel and Composite Structures
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• v.28 no.5
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• pp.589-606
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• 2018

The previous studies reflected the significant effect of neutral-axis position and coupling of in-plane and out-of-plane displacements on behavior of functionally graded (FG) nanobeams. In thin FG beam, this coupling can be eliminated by a proper choice of the reference axis. In shear deformable FG nanobeam, not only this coupling can't be eliminated but also the position of neutral-axis is dependent on through-thickness distribution of shear strain. For the first time, in this paper it is avoided to guess a shear strain shape function and the exact shape function and consequently the exact position of neutral axis for arbitrary gradation of higher order nanobeam are obtained. This paper presents new methodology based on differential transform and collocation methods to solve coupled partial differential equations of motion without any simplifications. Using exact position of neutral axis and higher order beam kinematics as well as satisfying equilibrium equations and traction-free conditions without shear correction factor requirement yields to better results in comparison to the previously published results in literature. The classical rule of mixture and Mori-Tanaka homogenization scheme are considered. The Eringen's nonlocal continuum theory is applied to capture the small scale effects. For the first time, the dependency of exact position of neutral axis on length to thickness ratio is investigated. The effects of small scale, length to thickness ratio, Poisson's ratio, inhomogeneity of materials and various end conditions on vibration and buckling of local and nonlocal FG beams are investigated. Moreover, the effect of axial load on natural frequencies of the first modes is examined. After degeneration of the governing equations, the exact new formulas for homogeneous nanobeams are computed.

• Journal of the Korean association of regional geographers
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• v.10 no.2
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• pp.341-355
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• 2004

This thesis is to analyze characteristic of sustainable development in the Nak-dong River. The results are summarized in the followings. 1) The principles which did not consider the equilibrium between development and environment, ecosystem, security. precautionary measure, equity could devise a plan, changes of economic land area, sand & gravel extractions from the riverbed, the river contamination cleanup, dam build 2) The rules which disregard polluter pay and opening participation in public affairs could input of too much province budget and manpower, project team. The measures to solve these problems could be proposed expansion of environmental infrastructure, sustainable sand & gravel extractions from the riverbed, fortifying the assistance of the residents who live in Dam construction site and the peripheral area of Dam, lower local fund rates in national projects, and the creation of management organization.