• Title, Summary, Keyword: 에너지 소산

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Energy Dissipation and Transfer among Wave Components during Directional Breaking Processes (다방향 쇄파 발생 전후의 파랑 성분간 에너지 전이 및 소산)

  • 홍기용;에스똘히오메자
    • Journal of Ocean Engineering and Technology
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    • v.17 no.6
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    • pp.1-6
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    • 2003
  • Wave energy dissipation and energy transfer between wave components, during the directional wave breakings, are investigated. Directional incipient and plunging breakers were generated by focusing the multi-frequency and multi-directional wave components at a designed location, based on a constant wave amplitude and a constant wave steepness frequency spectrum. The time series of surface wave elevation was measured at 9 different locations around the wave focusing point, using a wave gauge array. In order to examine the variation of the directional spreading function, the horizontal velocity of fluid motion was also measured. By comparing energy spectrums, before and after the breaking, the characteristics of energy dissipation and energy transfer, caused by wave breaking, are investigated. Their dependencies on directionality, as well as frequency, are analyzed. The breakings significantly dissipate wave energy, through energy transfer, in the upper region of the peak-frequency band, while enhancing wave energy in the low-frequency band.

The Characteristic of Te Recovery in Gold Concentrate Using Electrolysis (전기분해법을 이용한 금정광내 Te 회수 특성)

  • Kim, Bong-Ju;Cho, Kang-Hee;Jo, Ji-Yu;Choi, Nag-Choul;Park, Cheon-Young
    • Economic and Environmental Geology
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    • v.47 no.6
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    • pp.645-655
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    • 2014
  • In order to obtain pure metallic Te from gold concentrate, roasting treatment, hypochlorite leaching, Fe removal and electrolysis experiments were carried out. The contents of Au, Ag and Te from the concentrate sample and roasted sample were much more soluble in the hypochlorite solution than in aqua regia digestion, whereas the metals Pb, Zn, Fe and Cu were easier to leach with the aqua regia than the hypochlorite. With the addition of NaOH in the hypochlorite leaching solution prior to electrolysis, the Fe removal rate achieved was only 96% in the concentrate sample, while it reached 98% in the roasted sample. The results of electrolysis for 240 min, 98% of the metallic copper was recovered from the concentrate sample, while 99% was obtained from the roasted sample due to the removal of S by roasting. The amount of anode slime was also greater in the electrolytic solution with the roasted sample than with the concentrate sample. The results on the anode slime after the magnetic separation process showed the amount of metallic pure native tellurium recovered was greater in the roasted sample than in the concentrate sample.

Capacity Evaluation of Steel Damper Attached to Outside of Frame (골조 외부에 부착한 강재댐퍼의 성능 평가)

  • Lee, Hyun-Ho
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.5 no.4
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    • pp.382-388
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    • 2017
  • In this study, a basic study was carried out on the external strengthening method of public buildings. A steel damper is installed outside the specimen with a rocking wall and connected to the frame. Two specimens were fabricated, and the non-reinforced specimens utilized the existing results. As a result of evaluating the envelope curve, strength, stiffness and energy dissipation capacity, it was evaluated that the strength enhancement of the RW_P specimen externally reinforced plate damper was evaluated to be excellent. In addition, RW_S specimens with external S type damper shows a gentle envelop curve after maximum load, and it can be confirmed that the damper properly dissipates the seismic energy.

Seismic Capacity of Non-seismic Designed RC Framed Building Retrofitted by CBD System (CBD 시스템으로 보강된 비내진 RC 골조의 내진성능 평가)

  • Hur, Moo-Won;Lee, Sang-Hyun;Chun, Young-Soo
    • Journal of the Korea Concrete Institute
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    • v.27 no.6
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    • pp.625-632
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    • 2015
  • In this study, a comparative analysis have been conducted to examine seismic reinforcement effect of a school building that is designed with a CBD (Channel Beam Damper) system supported by H-frame with existing non-seismic RC frame. As a result of experiment, seismic reinforcement specimen with CBD system showed hysteretic characteristics of a large ellipse with great energy dissipation ability and increased strength and stiffness, while non-seismic design specimen showed rapid reduction in strength and brittle shear failure at top and bottom of the left and right column. In addition, comparing the stiffness reduction between the two specimens, CBD system was effective in preventing the reduction of stiffness. Energy dissipation ability of specimen reinforced by CBD system was about 4.0 times higher than the non-reinforced specimen. Such enhancement in energy dissipation ability could be considered as the result of improved strength and deformation for further application in designing of seismic reinforcement.

Characteristics of Energy Dissipation in Nano Shock Suspension System Using Silica Gel (세라믹 분말을 이용한 나노 충격 완화 장치의 에너지 소산 효율 특성에 대한 연구)

  • 문병영;정성원
    • Journal of the Earthquake Engineering Society of Korea
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    • v.7 no.3
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    • pp.17-22
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    • 2003
  • This paper presents an experimental investigation of a reversible colloidal seismic damper, which is statically loaded, The porous matrix is composed from silica gel (labyrinth or central-cavity architecture), coated by organo-silicones substances, in order to achieve a hydrophobic surface. Water is considered as associated lyophobic liquid. Reversible colloidal damper static test rig and the measuring technique of the static hysteresis are described. Influence of the pare and particle diameters, particle architecture and length of the grafted molecule upon the reversible colloidal damper hysteresis is investigated, for distinctive types and mixtures of porous matrices, Variation of the reversible colloidal damper dissipated energy and efficiency with temperature, pressure, is illustrated.

Seismic Capacity of Non-seismic Designed RC Framed Building Retrofitted by Double I-type Metallic Damper (더블 I형 감쇠장치로 보강한 비내진 RC 골조의 내진성능 평가)

  • Hur, Moo-Won;Chun, Young-Soo;Hwang, Jae-Seung;Kim, Jong-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.6
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    • pp.10-17
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    • 2015
  • In this study, to examine seismic reinforcement effect of a school building constructed prior to application of seismic design, a Double I-type damper supported by wall was installed to perform comparative analysis on existing non-seismic designed RC frame. As a result of experiment, while non-seismic designed specimen showed rapid reduction in strength and brittle shear destruction as damages were focused on top and bottom of left and right columns, reinforced specimen showed hysteretic characteristics of a large ellipse with great energy absorption ability, exhibiting perfectly behavior with increased strength and stiffness from damper reinforcement. In addition, as a result of comparing stiffness reduction between the two specimens, specimen reinforced by shear wall type damper was effective in preventing stiffness reduction. Energy dissipation ability of specimen reinforced by Double I-type damper was about 3.5 times as high as energy dissipation ability of non-reinforced specimen. Such enhancement in energy dissipation ability is considered to be the result of improved strength and deformation.

A Numerical Study for the Scalar Dissipation Rate and the Flame Curvature with Flame Propagation Velocity in a Lifted Flame (부상화염에서 화염전파속도에 따른 스칼라소산율과 곡률반경에 대한 수치적 연구)

  • Ha, Ji-Soo;Kim, Tae-Kwon;Park, Jeong;Kim, Kyung-Ho
    • Journal of the Korean Institute of Gas
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    • v.14 no.3
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    • pp.46-52
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    • 2010
  • Flame propagation velocity is the one of the main mechanism of the stabilization of triple flame. To quantity the triple flame propagation velocity, Bilger presents the triple flame propagation velocity, depending on the mixture fraction gradient, based on the laminar jet flow theory. However, in spite of these many analyses, there has not been any attempt to quantify the triple flame propagation velocity with the flame radius of curvature and scalar dissipation rate. In the present research, there was discussion about the radius of flame curvature and scalar dissipation rate, through the numerical study. As a result, we have known that the flame propagation velocity was linear with the nozzle exit velocity and scalar dissipation rate decreases nonlinearly with the flame propagation velocity and radius of curvature of flame increases linearly. Also radius of curvature of flame decreases non-linearly with the scalar dissipation rate. Therefore, we ascertained that there was corelation among the scalar dissipation rate, radius of flame curvature and flame propagation velocity.

A Study on the Seismic Performance of Energy-Dissipating Sacrificial Devices for Steel Plate Ginder Bridges (강합성 거더교에 적용된 희생부재형 에너지소산장치의 내진성능에 관한 연구)

  • Cho, Kwang-Il;Gwak, Pil-Bong;Mha, Ho-Seong;Kim, Sang-Hyo
    • Journal of the Earthquake Engineering Society of Korea
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    • v.11 no.3
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    • pp.87-96
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    • 2007
  • A new Energy-Dissipating Sacrificial Device (EDSD) is developed for steel plate girders, which can effectively dissipate the energy stored in the structures during seismic actions. To verify the performance of the EDSD, various seismic responses of a sample bridge with the EDSD are analyzed in terms of energy, member forces and deformation. The full scale model tests are conducted to certify the performance of the EDSD when it is applied on existing bridges. Using the improved hysteretic model of the sacrificial member, the seismic analysis for an example bridge is performed. The results show that the proposed EDSD under seismic excitations can significantly decrease the energy stored in the bridge structures and reduce the relative displacements of each superstructure to the ground. The EDSD is also found to function as a structural fuse under strong ground motions, sacrificing itself to absorb the excessive energy. Consequently, economical enhancement of the seismic performance of bridges can be achieved by employing the newly developed energy-dissipating sacrificial device.

Centrifugal Test on Behavior of the Dolphin Structure under Ship Collision (선박충돌 시 돌핀 구조물의 거동에 대한 원심모형실험)

  • Oh, SeungTak;Bae, WooSeok;Cho, SungMin;Heo, Yol
    • Journal of the Korean GEO-environmental Society
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    • v.12 no.1
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    • pp.61-70
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    • 2011
  • The impact protection system consists of an arrangement of circular sheet pile cofferdams-denoted dolphin structuredeeply embedded in the seabed, filled with crushed rock and closed at the top with a robust concrete cap. Centrifuge model tests were performed to investigation the behaviors of dolphins in this study. Total 7 quasi-model tests and 11 dynamic model tests were performed. The main experimental results can be summarized as follows. Firstly, The experimental force-displacement results for quasi-static tests show a limited influence on the initial stiffness of the structure from the change in fill density and the related change in the stiffness of the fill. And by comparing the dissipation at the same dolphin displacement it was found that the denser fill increase the dissipation by 16% for the 20m dolphin and by 23% for the 30m dolphin. The larger sensitivity for the large dolphin is explained by a larger contribution to the dissipation from strain in the fill. In low level impacts the dynamic force-response is up to 26~58% larger than the quasi-static and the dissipation response is showed larger in small displacement. Hence, it is concluded conservative to use the quasi-static response characteristics in the approximation of the response, and it is further concluded that the dolphin resistance to low level impacts is demonstrated to be equivalent and even superior to the high level impacts.