• Advances in environmental research
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• 제4권2호
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• pp.135-142
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• 2015

In this study, we evaluated the adsorption/desorption of uranium (U) in pure soil environment using continuous column reactor. We additionally investigated the adsorption/desorption mechanism of U on vivianite surface in molecular scale using quantum calculation. We observed that below $0.1{\mu}M$ of U was detected after 20 d from U injection ($1{\mu}M$) in adsorption test. However, all of absorbed U was detached from vivianite surface in 24 h by injection of CARB solution ($1.44{\times}10^{-2}M\;NaHCO_3$ and $2.8{\times}10^{-3}M\;Na_2CO_3$). Based on exchange energy calculation, we found that $UO_2(CO_3)_2{^{2-}}$ and $UO_2(CO_3)_3{^{4-}}$ species have higher repulsive energy than $UO_2(OH)_2$ species. The results obtained from this study could be applied to predict the behavior of uranium in contaminated and remediation sites.

• 한국터널지하공간학회 논문집
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• 제9권4호
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• pp.361-375
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• 2007

본 논문에서는 터널시공시 지하수 저하를 동반하는 시공조건에서 발생하는 지표침하 특성에 관한 연구내용을 다루었다. 이를 위해 먼저 지하수 저하로 인한 지반침하 문제에 대한 국내외 기존 연구내용을 살펴보았으며, 지하수 유동시 응력-간극수압 상호작용이 고려된 유한요소해석 모델을 구축하고 이론적 검증을 통해 유한요소해석 모델의 타당성을 검토하였다. 구축된 유한요소해석 모델을 토대로 다양한 시공조건에 대한 매개변수 연구를 수행하고 그 결과를 토대로 지하수 유동시 지반침하에 영향을 미치는 주요 인자를 검토하였으며, 아울러 터널시공이 지하수 저하를 동반하는 시공조건에서의 지표침하 특성을 기존의 이론과 연계하여 고찰하였다.

• Journal of Microbiology and Biotechnology
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• 제12권1호
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• pp.31-38
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• 2002

Bacteria have evolved various types of resistance mechanism to toxic heavy metals, such as arsenic and antimony. An arsenical and antimonial resistant bacterium was isolated from a shallow creek draining a coal-mining area near Taebaek City, in Kangwon-Do, Korea. The isolated bacterium was identified and named as Pseudomonas sp. KM20 after biochemical and physiological studies were conducted. A plasmid was identified and its function was studied. Original cells harboring the plasmid were able to grow in the presence of 15 mM sodium arsenite, while the plasmid-cured (plasmidless) strain was sensitive to as little as 0.5 mM sodium arsenate. These results indicated that the plasmid of Pseudomonas sp. KM20 does indeed encode the arsenic resistance determinant. In growth experiments, prior exposure to 0.1 mM arsenate allowed immediate growth when they were challenged with 5 mM arsenate, 5 mM arsenite, or 0.1 mM antimonite. These results suggested that the arsenate, arsenite, and antimonite resistance determinants of Pseudomonas sp. KM20 plasmid were indeed inducible. When induced, plasmid-bearing resistance cells showed a decreased accumulation $of\;73^As$ and showed an enhanced efflux $of\;^73As$. These results suggested that plasmid encoded a transport system that extruded the toxic metalloids, resulting in the lowering of the intracellular concentration of toxic oxyanion. In a Southern blot study, hybridization with an E. coli R773 arsA-specific probe strongly suggested the absence of an arsA cistron in the plasmid-associated arsenical and antimonial resistance determinant of Pseudomonas sp. KM20.

• Structural Engineering and Mechanics
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• 제52권1호
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• pp.75-87
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• 2014

To analyze the tension performance of laminated rubber bearings under tensile loading, a theoretical tension model for analyzing the rubber bearings is proposed based on the theory of elasticity. Applying the boundary restraint condition and the assumption of incompressibility of the rubber (Poisson's ratio of the rubber material is about 0.5 according the existing research results), the stress and deformation expressions for the tensile rubber layer are derived. Based on the derived expressions, the stress distribution and deformation pattern especially for the deformation shapers of the free edges of the rubber layer are analyzed and validated with the numerical results, and the theory of cracking energy is applied to analyze the distributions of prediction cracking energy density and gradient direction. The prediction of crack initiation and crack propagation direction of the rubber layers is investigated. The analysis results show that the stress and deformation expressions can be used to simulate the stress distribution and deformation pattern of the rubber layer for laminated rubber bearings in the elastic range, and the crack energy method of predicting failure mechanism are feasible according to the experimental phenomenon.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1008-1013
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• 2003

This paper concerns the structural characteristic analysis and evaluation on the hydrostatic guide way and feeding system of a high precision centerless grinder for machining ferrules. In order to realize the required accuracy of ferrules with sub-micron order, the axial stiffness and motion accuracy of feeding system have to become higher level than those of existing centerless grinders. Under these points of view, the physical prototype of feeding system consisted of steel bed, hydrostatic guide way and ballscrew feeding mechanism is designed and manufactured for trial. Experimental results show that the axial and vertical stiffnesses of the physical prototype are very low as compared with those design values. In this paper, to reveal the cause of these stiffness difference, the structural deformations on the virtual prototype of feeding system are analyzed based on the finite element method under experimental conditions. The simulated results illustrate that the deformation of front ballscrew support-bearing bracket is the main cause of reduction in the axial stiffness of feeding system, and the deflection of bed structure and the bending deformation of hydrostatic guide rails are the main causes of reduction in the vertical stiffness of feeding system.

• 동의생리병리학회지
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• 제17권3호
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• pp.765-770
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• 2003

To explore the possible cancer agent from oriental prescriptions, we have examined its antitumor and anti metastatic activities of Kamibojungikgi-tang(KBIT). KBIT extracts exhibited cytotoxicity against P388, A549 and B16-F10 cell lines in a dose-dependent manner and showed antiadhesive effect of A549 cell to complex extracellular matrix at 1 ㎎/㎖ in vitro. In DNA topoisomerase I assay, KBIT extracts showed strong inhibitoty effect in a dose-dependent manner. In pulmonary colonization assay with B16BL6, a number of colonies in the lungs were decreased effectively in KBIT treated group as compared with control group. Moreover, in CAM assay, KBIT extracts significantly inhibited angiogenesis at 15㎍/egg as compared with control. The T/C% was 141% in KBIT treated group in S-180 bearing ICR mice. From the above results it was concluded that KBIT had antitumor and anti metastatic activities. So it is expected to be clinically helpful on the prevention and treatment of cancer, although it is still necessary to study its mechanism on molecular biology and immunology.

• 대한기계학회논문집A
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• 제28권7호
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• pp.896-903
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• 2004

This paper proposes the structural characteristic analysis and evaluation on the hydrostatic guide way and feeding system of a high-precision centerless grinder for machining ferrules. In order to realize the required accuracy of ferrules with sub-micron order, the axial stiffness and motion accuracy of feeding system have to become higher level than those of existing centerless grinders. Under these points of view, the physical prototype of feeding system composed of steel bed, hydrostatic guide way and ballscrew feeding mechanism is designed and manufactured for trial. Experimental results show that the axial and vertical stiffnesses of the physical prototype are very low as compared with those design values. In this paper, to reveal the cause of these stiffness difference, the structural deformations on the virtual prototype of feeding system are analyzed based on the finite element method under experimental conditions. The simulated results illustrate that the deformation of front ballscrew support-bearing bracket is the main cause of reduction in the axial stiffness of feeding system, and the deflection of bed structure and the bending deformation of hydrostatic guide rails are the main causes of reduction in the vertical stiffness of feeding system.

• Steel and Composite Structures
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• 제28권6호
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• pp.691-708
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• 2018

An innovative Hybrid Passive Resistive configuration for Truss Girder Frames (HPR-TGFs) is introduced in the present study. The proposed system is principally consisting of Fluid Viscous Dampers (FVDs) and Buckling Restrained Braces (BRBs) as its seismic resistive components. Concurrent utilization of these devices will develop an efficient energy dissipating mechanism which is able to mitigate lateral displacements as well as the base shear, simultaneously. However, under certain circumstances which the presence of FVDs might not be essential, the proposed configuration has the potential to incorporate double BRBs in order to achieve the redundancy of alternative load bearing paths. This study is extending the modern Direct Displacement Based Design (DDBD) procedure as the design methodology for HPR-TGF systems. Based on a series of nonlinear time history analysis, it is demonstrated that the design outcomes are almost identical to the pre-assumed design criteria. This implies that the ultimate characteristics of HPR-TGFs such as lateral stiffness and inter-story drifts are well-proportioned through the proposed design procedure.

• Journal of Forest and Environmental Science
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• 제30권3호
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• pp.267-276
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• 2014

Collection of lichen together with tree twigs of oak and other trees bearing abundant growth of lichens is a common practice among the villagers and the rivals residing near Oak forests in Kumaun Himalaya. Nainital forest division represents about Twenty nine percent vegetation of the Oak forest in Kumaun Himalaya. In Kumaun, the lichen trade share is decreasing at an alarming rate of 21.93% which requires immediate actions by the Government. Lichen contributed significantly to household earnings with off-farm activities and this sector was found second highest income creator after Agriculture. It is a source of cash income during the season of extraction, which increases economic access to food. It has been observed in the present study that the secondary collector and transporters together get maximum share (>50%) of income generated from lichen, thus economic exploitation of the poorly educated people by the traders was still prevalent in the area. To improve the socio-economic standard of the people of Kumaun, it may is necessary to increase and improve the lichens resources of the area. There is a strong need for scientific management, best harvesting practices and strict monitoring of resources. The present study was conducted to assess the present and future resource potential for the conservation and sustainable management of lichens, existing market mechanism, role of Lichens in economic upliftment and livelihood generation of rural communities in Kumaun Himalaya.

• 한국소음진동공학회논문집
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• 제12권5호
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• pp.338-345
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• 2002

The study presents a new testing and analysis method for brake judder on vehicle. For the identification of the excitation mechanism of a brake judder, it is necessary to measure the dynamic brake disc geometry during braking on vehicle. The non-contact sensor system was used to monitor the brake disc geometry. Brake torque variation (BTV) caused by disc thickness variation (DTV) is the primary excitation for brake judder. The mechanical effects generating BTV are linked not only to initial manufacturing tolerances but also to uneven wear. Therefore, the brake disc geometry should be strictly managed to initial condition. The aim of this study has been to measure the dynamic DTV and runout on vehicle and analyze the influence of test parameters on brake judder and compare the disc component with vehicle matching about the DTV Profile. As a result of this study, The amplitude of brake judder is proportional to vehicle speed and fluid pressure fluctuation on braking. The major sources of brake judder are directly related to disc thickness variation and side runout variation of corner assembly (disc, hub. bearing).