• Journal of the Society of Naval Architects of Korea
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• v.42 no.4 s.142
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• pp.357-367
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• 2005

A numerical method is developed for the hydroelastic response of the Very Large Floating Structure considering the sea-bottom topography. The sea-bottom effects on the hydroelastic response of the floating structure is studied. The sea-bottom topography should be considered when the floating structure is constructed near the shore. To investigate the sea-bottom effects, four different sea-bottom topographies are considered in this study. finite-element method based on the variational formulation is used in the fluid domain, The pontoon-type floating structure is modeled as the Kirchhoff plate. The mode superposition method is adopted for the hydroelastic behavior of the floating structure.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.444-449
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• 2004

The design modification of bottom guide structures of the instrumented capsule, which is used for the irradiation test in the HANARO reactor, was required because of the trouble of the bottom guide arm's pin during irradiation. The previous structure with 3-pin arms was changed into the cone shape of one body. The specimens of the bottom end cap ring with three different sizes (${\Phi}68/70/72mm$) were designed and manufactured. The out-pile tests for the capsule with previous and new three bottom guide structures were performed in the one-channel flow test facilities. In order to evaluate the compatibility with HANARO and the structural integrity of the capsule, a loading/unloading, a pressure drop, a thermal performance, a vibration, and an endurance test were conducted. From out-pile test results, the capsule with the cone shape bottom guide structures was found to be more stable than the previous structure and the optimized size of the bottom guide structure selected was 70mm in diameter. It is expected that the new bottom guide structures will be applicable to all material and special capsules which will be designed and manufactured for the irradiation tests in the future.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.385-388
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• 2009

We have investigated the effect of the device structure on the performance of polycrystalline ZnO TFT and amorphous AZTO TFT with top gate and bottom gate structure. While the mobility of both TFTs showed relatively similar value in a top and bottom gate structure, bias stability was quite different depending on the device structure. Top gate TFT showed much less Vth shift under positive bias stress compared to that of bottom gate TFT. We attributed this different behavior to the defects formation on the gate insulator induced by energetic bombardment during the active layer deposition in a bottom gate TFT. We suggest the top gate oxide TFT would show more stable behavior under the Vgs bias.

• Structural Engineering and Mechanics
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• v.64 no.2
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• pp.233-241
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• 2017

Earlier numerous studies have been done on implementation of Tuned Liquid Damper (TLD) for structural vibration control by many researchers. As per current review there is no significant study on a sloped bottom TLD. TLD's are passive devices. A TLD is a tank rigidly attached to the structure and filled partially by liquid. When fundamental linear sloshing frequency is tuned to structure's natural frequency large sloshing amplitude is expected. In this study set of experiments are conducted on flat bottom and sloped bottom TLD at beach slope $20^{\circ}$, $30^{\circ}$ and $45^{\circ}$, for different types of structures, mass ratio, and depth ratio to investigate the overall effectiveness of TLD and specific effect of TLD parameters on structural response. This experimental study shows that a properly designed TLD reduces structural response. It is also observed that effectiveness of TLD increases with increase in mass ratio. In this experimental study an effectiveness of sloped bottom TLD with beach slope $30^{\circ}$ is investigated and compared with that of flat bottom TLD in reducing the structural response. It is observed from this study that efficiency of sloped bottom TLD in reducing the response of structure is more as compared to that of flat bottom TLD. It is shown that there is good agreement between numerical simulation of flat bottom and sloped bottom TLD and its experimental results. Also an attempt has been made to investigate the effectiveness of sloped bottom TLD with beach slope $20^{\circ}$ and $45^{\circ}$.

• Ocean and Polar Research
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• v.29 no.2
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• pp.113-121
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• 2007

The sound wave in the sea propagates under the effect of water depth, sound speed structure, sea surface roughness, bottom roughness, and acoustic properties of bottom sediment. In shallow water, the bottom sediments are distributed very variously with place and the sound speed structure varying with time and space. In order to investigate the seasonal propagation characteristics of low-frequency sound wave in the Yellow Sea, propagation experiments were conducted along a track in the middle part of the Yellow Sea in spring, summer, and autumn. In this paper we consider seasonal variations of the sound speed profile and propagation loss based on the measurement results. Also we quantitatively investigate variation of bottom loss by dividing the propagation loss into three components: spreading loss, absorption loss, and bottom loss. As a result, the propagation losses measured in summer were larger than the losses in spring and autumn, and the propagation losses measured in autumn were smaller than the losses in spring. The spreading loss and the absorption loss did not show seasonal variations, but the bottom loss showed seasonal variations. So it was thought that the seasonal variation of the propagation loss was due to the seasonal change of the bottom loss and the seasonal variation of the bottom loss was due to the change of the sound speed profile by season.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.717-720
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• 2001

Ferroelectric lead ziroconate titanate (PZT) thin film were fabricated on the different bottom electrodes. Both Ru and Ru/RuO$_2$bottom electrodes were deposited by RF-magnetron sputteirng method. The structure phase and surface morphology of the PZT thin film were largely affected by the bottom electrode. It was observerd that used of Ru/RuO$_2$double electrode reduced leakage current and better ferroelectric properties compare with RuO$_2$bottom electrode. From these results, Ru/RuO$_2$hybride bottom electrode is thought to be the available structure for the bottom electrode.

• Journal of Korea Ship Safrty Technology Authority
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• s.23
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• pp.2-13
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• 2007

With the effectuation of the amendment of MARPOL 73/78 on 5 April 2005, enforcement regulations of Marine Pollution Prevention Act were revised in domestic on 12 March 2005 that double hull structure was required to the small single bottom oil tankers under DWT(deadweight tonnage) 500 ton for the protection of the marine pollution casualties. The objective of this study is to develop the double bottom structure of small oil tanker under DWT 500 ton with superior crashworthiness and to establish its suitable standard to double bottom structure. The promoting strategy of this R&D is classified into the crashworthy structural analysis of small oil tankers using LS/DYNA3D code and the examination of their damage stabilities according to tonnage. It could be thought that the desirable inner bottom height should be above the B/7.5 and its minimum height 0.65m for the domestic small oil tanker under DWT 500ton.

• Ocean and Polar Research
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• v.27 no.2
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• pp.115-123
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• 2005

Recently, it has been observed in the East Sea that temperature increases below the thermocline, and dissolved oxygen increase in the intermediate layer but decrease below it. The layer of minimum dissolved oxygen deepens and the bottom homogeneous layer in oxygen becomes thinner. It emerges very probably that these changes are induced by the mode change of deep water formation associated with global warming. To further support this hypothesis, a one-dimensional model experiment is performed. First, a thermal profile is obtained by injecting a cold and high oxygen deep water into the bottom layer, say the bottom mode. Then, two thermal profiles are obtained from the bottom mode profile by assuming that either all the deep water introduce into the intermediate layer has been initiated, say the intermediate mode, or that only a part of the deep water has been initiated into the intermediate layer, say the intermediate-bottom mode. The results, from the intermediate-bottom mode experiment are closest to the observed results. They show quite well the tendency for oxygen to increase in the intermediate layer and the simultaneous thinning of the bottom homogeneous layer in oxygen. Therefore, it can be said that the recently observed slow variation of the thermal structure might be associated with changes in the deep water formation from the bottom mode to the intermediate-bottom mode.

• Korean Journal of Materials Research
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• v.9 no.4
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• pp.368-372
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• 1999

The suggested electrode structure of MOCVD-Pt/sputtered-Ru/polysilicon has an excellent adhesion with increasing annealing temperatures and shows a stable electrode structure up to $600^{\circ}C$. However, the ruthenium used for barrier layer increased the roughness of platinum bottom electrodes because ruthenium diffused through the Pt bottom electrode and reacted with oxygen during the annealing above $700^{\circ}C$. The surface roughness increased the resistivity of Pt bottom electrodes. The resistivity of samples annealed at $600^{\circ}C$ was about $13\mu$Ω.cm. The electrode structure was possible to apply for ferroelectric thin film integration of semiconductor memory devices.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.846-851
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• 2003

This study was performed to develop the lightweight polymer concrete using expanded clay and perlite to improve workability, durability and chemical resistance for bottom draining structure under severe condition. This paper was composed of two parts. One is to invest the physical and mechanical properties of lightweight polymer concrete using synthetic lightweight aggregate, the other is to the develop products for bottom draining structure. Physical and mechanical test for lightweight polymer concrete was performed unit weight, compressive and flexural strength, chemical resistance, accelerated weathering test, absorption ratio and optimum mix for lightweight polymer concrete was designed. Also, products for bottom draining structures by optimum mix of lightweight polymer concrete was made draining trench of small size.