• Structural Engineering and Mechanics
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• v.74 no.4
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• pp.495-502
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• 2020

This study investigated the effects of prestressing force on the natural frequency of concrete beams considering changes in the self-weight of the beam. For this, a finite element formulation was derived to account for the increase in the stiffness of a beam-tendon system due to the axial force and deformation induced by prestressing of the tendon. The developed finite element formulation was validated with the data obtained in laboratory experiments. The experimental natural frequencies of the small prestressed concrete (PSC) beam specimens were consistent with those obtained using the proposed method. The first natural frequency increased almost linearly as the prestressing force increased. The proposed method was then applied to four actual PSC bridges typically employed in the field. Different from the laboratory specimens, the first natural frequencies of the actual PSC bridges barely changed or increased with increasing prestressing force. The results of an analytical parametric study showed that the increase in the natural frequency strongly depended on the magnitude of the prestressing force relative to the total weight of the structure. Thus, the variation in the natural frequencies of the actual PSC bridges with high total weight relative to the prestressing force was negligible due to the application of the prestressing force.

• Journal of the Korean Applied Science and Technology
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• v.28 no.4
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• pp.393-401
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• 2011

Natural Curcumin belongs to Zingiber Officinale Roscoe was known to possess natural odor, natural taste, natural color, and other pharmaceutical & chemical characteristics. Natural Curcumin extract was made to use ethanol as a solvent was to show a yellow color having state of solid powder and an active component. Natural Curcumin extract tested pharmaceutical & chemical experiment to dilute in curcumin 1%-water solution. Curcumin extract tested antimicrobial experiment using microbe, and tested dye experiment using fiber. Some conclusions in the result of characteristics experiment was obtained as follow. The result of antimicrobial experiment showed that the growth of staphylococcus aureus (ATCC-001) and aspergillus niger (ATCC-002) as microbes decreased according to passage of time. This phenomenon could know that Curcumin compoment showed influence to antimicrobial effect. Also, the result of dye experiment showed that cotton and sick with fiber dyeing dyed in direction of dark yellow color. This phenomenon could know that Curcumin extract showed influence to dyeing effect in observation of optical electron microscope(OEM.) The result of instrument analysis ascertained inorganic components of K(53.300ppm), Na(1.150ppm), Ca(0.711ppm), Ti(0.351ppm), Li(0.256ppm), Cu(0.233ppm) etcs from Curcumin component with ICP/OES, and ascertained organic components of propanoic acid(1.859), benzene(10.814), phenol(14.194) etcs from Curcumin component with GC/MSD.

• Proceedings of the Zoological Society Korea Conference
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• 2001.10a
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• pp.236.1-236
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• 2001

No Abstract, See Full Text

• Journal of Environmental Science International
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• v.15 no.11
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• pp.1069-1075
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• 2006

Starting from Jan. 1, 2006, pursuant to Article 28 of the Natural Environment Conversation Act for development acts with natural Landscape as a subject, the Consultation System on the Effects of Natural Landscape has been put into force in order to, in advance, analyze and predict the effects of natural Landscape according to the implementation of various development plans and development projects and also minimize adverse effects by preparing plans to reduce the effects. The consultation on the effects of natural Landscape is based on the objective and scientific approaches of data with Landscape to minimizing the effects of natural Landscape by developments with the preservation, restoration, outlook and harmonization as basic principles, and looking into the review of natural Landscape damage and harmonization of the site to be developed. For more objectively analyzing the visual effects of natural Landscape according to development acts, the purpose of this study is to provide basic materials of continued Landscape management plans in the planning stage of development plans and after the completion of developments by analyzing the sensitivity of Landscape and deriving areas, whose Landscape will be damaged, mainly focusing on the area of visibility using GIS.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.384-387
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• 2000

Heteropolysaccharide-7 (PS-7) was produced by Beijerinckia indica HS-2001 under aerobic condition. Production of PS-7 was investigated under various ratios of glucose as carbon source to ammonium nitrate as nitrogen source. Maximal production of PS-7 was 7.13 g/l when concentrations of glucose and ammonium nitrate were 10 g/l and 0.3 g/l, respectively. But its conversion rate from glucose was as low as 7 %. The highest conversion rate of PS-7 was 46% when those of glucose and ammonium nitrate were 1.0 g/l and 0.3 g/l, respectively.

• KIEAE Journal
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• v.16 no.6
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• pp.129-134
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• 2016

Today, natural ventilation systems are widely applied in multi-family housing. However, studies using the wind data trend line of the blower door test are insufficient. Purpose: Through this study, we will propose a computational method about ventilation performance of natural ventilation systems by conducting blower door test. Method: First, we sealed the gaps between the main systems including the natural ventilation system and conducted the blower door test. Next, the natural ventilation system was opened, the blower door test was conducted, and the difference in air flow rate between when closed and when opened was checked. Blower door test was carried out with a pressure difference of 50 Pa. Result: Therefore, the ventilation performance of the natural ventilation system was checked by drawing a trend line using the data to calculate the air flow rate at 2 Pa of the natural ventilation equipment standard pressure difference.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.580-585
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• 2004

The purpose of this study is the stability evaluation of soil slope according to inclination of upper natural slope. Upper natural slope breeds loss of slope by inflow in slope of surface water by rainfal1 and f1uctuation of amount of materials in slope through method of cutting slope according to degree of inclination. Basis of standard inclination does not consider of inclination of upper natural slope and is presented uniformly. Therefore, in this study, analyzed stability of inclination of upper natural slope through limit equilibrium analysis. Result is same as following. First, safety factor through limit equilibrium analysis is almost direct decrease when gradient of soil slope is 1:1.2, 1:1.5. However, when gradient of soil slope is 1:1.0, 1:0.7, if sinclination of upper natural slope are $20^{\circ}$, it shows tendency that decrease of safety factor becomes low rapidly. Second, when when gradient of soil slope is fixed, inclination of upper natural slope increase tendency(maximum 3.0 times) that decrease of safety factor.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.568-572
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• 2001

An industrial vibratory conveyor system is devised for large-scale feeding by the low-power, using natural frequency of the system. The important thing in this system is to determine the natural frequency and to drive by it. The purpose of this study is to build up reliance on the system with changing of element parameters for vibration characteristics of balancing type vibratory conveyor by using F.E.M. modeling. For investigating the natural frequency, modal testing is performed by using impact hammer, accelerometer and LMS/Vibration Analysis System. Experimental results are compared with F.E.M results. The results of the comparisons within the errors of less than 2 percent can verify the reliability of the F.E.M. analysis of the system. Also we can verify that the characteristics of natural frequency have linearly decreased(-6%) as adding the mass($50{\sim}600kg$). We can find that controlling driving frequency is necessary for triggering the natural frequency, but natural frequency is less affected by adding the mass on the balancing weight.

• Bulletin of the Korean Chemical Society
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• v.27 no.8
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• pp.1149-1153
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• 2006

LPC analogues including natural and unnatural LPC, 3-L-2-PC, acetylated LPC and ethylene glycol derivative are prepared from D-mannitol using in convenient procedures by only changing the synthetic sequences, and their protective activities against cecal ligation and puncture (CLP)-induced severe sepsis are compared. The chirality at C2 position in LPC is found to be required as (S)-configuration for sepsis inhibition, comparing from the protection activity between LPC 6 and unnatural LPC 8. The hydroxyl functionality is also very important and required at C2 or C3 position as shown in the protection activities of ethylene glycol analogue 11 and 3-L-2-PC 9.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.10 no.5
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• pp.1-9
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• 2007

Local government with abundant natural resources should consider the nature conservation oriented planning process for the sustainable development. With this regard, the aim of this study is to provide a substantial methodology to support the decision-making process to designate the conservation areas. The objectives of the proposed methodology is to conserve natural resources in the local government's territory through quantitatively assessing the values of the natural resources based on various ecological factors such as topography, flora and fauna. In order to test the usability of the method, Gangneung City in Kangwon-Do is selected considering the latest data availability. Based on the assessment process land use of the subjected city could be categorized into 4 levels of conservative area, conservative level 1 area, conservative level 2 area, and conservative level 3 area. Among them, conservative area and conservative level 1 area could be combined as natural resources conservation area and the others could be regarded as buffer and transitional area. Especially conservation area is surrounded by conservation level 2 area. Conclusively, the GIS methods adopted in this could be the efficient illustrative tool to assess the local natural resource values with the central government established nature-environmental information systems.