• International Journal of Naval Architecture and Ocean Engineering
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• 제10권3호
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• pp.294-306
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• 2018

Most offshore structures including offshore wind turbines, ships, etc. suffer from the impulsive pressure loads due to slamming phenomena in rough waves. The effects of elasticity & plasticity on such slamming loads are investigated through wet free drop test results of several steel unstiffened flat bottom bodies in the rectangular water tank. Also, their cumulative deformations by consecutively repetitive free drops from 1000 mm to 2000 mm in height are measured.

• 상하수도학회지
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• 제31권6호
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• pp.599-609
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• 2017

Desalination plants have been recently constructed in many parts of the world due to water scarcity caused by population growth, industrialization and climate change. Most seawater desalination plants are designed with a submarine pipeline for intake and discharge. Submarine pipelines are installed directly on the bottom of the water body if the bottom is sandy and flat. Intake is located on a low-energy shoreline with minimal exposure to beach erosion, heavy storms, typhoons, tsunamis, or strong underwater currents. Typically, HDPE (High Density Polyethylene) pipes are used in such a configuration. Submarine pipelines cause many problems when they are not properly designed; HDPE pipelines can be floated or exposed to strong currents and wind or tidal action. This study examines the optimal design method for the trench depth of pipeline, analysis of on-bottom stability and dilution of the concentrate based on the desalination plant conducted at the Pacific coast of Peru, Chilca. As a result of this study, the submarine pipeline should be trenched at least below 1.8 m. The same direction of pipeline with the main wind is a key factor to achieve economic stability. The concentrate should be discharged as much as high position to yield high dilution rate.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1996년도 춘계 학술대회논문집
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• pp.52-57
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• 1996

Mixing is most important for developing an electric washer which transforms angular momentum from rotating solid wall to laundry clothes inside it. For magnification of this mixing effect, some inventions are introduced to washing machine system, i. e., washing plate, washing rod, and even for washing cap in a model of a Korean manufacture. However, the previous efforts show dissatisfaction up till now. In this paper, a triumph to enhance mixing effects to increase washing performance is presented and verified by numerical investigation. The present model to simulate a washing tub is the simple circular cylinder with two endwall disks which is completely filled with a viscous liquid. The present improvement is to change mounting position of a bottom disk of the model cylinder. Therefore, the aim of this work just proposes a new idea, which is numerically inspected, to a producer of washing machine, In detail, this invention is alternating the mounting position of a rotating bottom disk. Actually skewed pulsator is placed in steady of a flat disk, so the two endwall disks at top and bottom are not in parallel. The angle between an inclined bottom disk and the horizontal plane is fixed as 5 degree and physical domain to consider poses a sliced cylinder. Flow fields in both a right circular cylinder and the present improved model are fully depicted by numerical integration on a body fitted nonorthogonal regular uniform grid system. Numerical data to explain flow structure are plotted for understanding of the effects of the inclined disk. Also enhanced mixing effects by the inclined rotating disk are gauged by accurate numerical data used in this work.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 봄 학술발표회 논문집
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• pp.402-403
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• 2003

Garment manufacture represents the final stage of processing a finished fabric. The main task of the garment manufacturer is to produce shell structures out of flat fabrics to match the shape of the human body, and the most acceptable means of joining textile materials for apparel use is by sewing. On the sewing process, the bottom layer is pushed forward by the feed-dog, but the presser foot tends to retard the passage of the top layer. Since the friction between the layers is low, is possible that the components will move out of phase and pucker. (omitted)

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 춘계 학술대회논문집
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• pp.35-41
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• 2004

A numerical investigation has been made for flows in an axisymmetric circular cylinder with a rotating cone located at the bottom of the container. The axisymmetric container is completely filled with a viscous fluid. Major parameter for the present research is the vertex angle of the cone, otherwise Reynolds number of fluid and aspect ratio of the vessel is fixed. Main interest is in vortex breakdown of meridional circulation by rotation of the cone with respect to the longitudinal axis of the cylinder. The method to this problem is numerically to integrate momentum and continuity equations on a generalized body fitted grid system. The pattern of vortex breakdown is quite different from that in a right circular cylinder with flat end wall disks. Flow visualization photographs of a preceeding work are compared with the present numerical results.

• 한국태양에너지학회 논문집
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• 제21권3호
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• pp.61-68
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• 2001

This study represents numerical analysis on the thermal and fluid flow of the air layer in a solar collector. The boundary conditions was assumed that the top and bottom wall of the air layer have a heating and cooling surface, respectively, and this calculation model have a solid body with a cooling temperature of $20^{\circ}C$. As the results of simulations, the magnitudes of the velocity vectors and isotherms are increased proportionally to the tilt angles. As the tilt angle is increased, the mean Nusselt numbers are increased and the maximum value of the mean Nusselt number was appeared at tilt angle $\theta=75^{\circ}$.

• 설비공학논문집
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• 제9권1호
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• pp.55-63
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• 1997

A numerical investigation has been made for flows in an axisymmetric circular cylinder with an impulsively rotating cone located at the bottom of the container. The axisymmetric container is completely filled with a viscous fluid. Major parameter for the present research is only the vertex angle of the cone, otherwise Reynolds number and aspect ratio of the vessel are fixed. Main interest concerns on the vortex breakdown of meridional circulation by impulsive rotation of the cone with respect to the longitudinal axis of the cylinder. Numerical method has been used to integrate momentum and continuity equations on a generalized body-fitted grid system. The pattern of vortex breakdown is quite different from that in a right circular cylinder with flat endwall disks. The flow visualization photograph of the preceeding work by Escudier is compared with the present numerical results and the two results are in good agreements. Also flow data are plotted to gain a deep understanding for the present phenomena of the vortex breakdown. The conclusions of this work are clearly explained by the classical theory of the vortex flows in a finite geometry.

• 재활복지공학회논문지
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• 제5권1호
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• pp.47-52
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• 2011

기능성 발보조기는 신발 착용 시 발바닥과 직접 접촉되어 비정상적인 신체 분절의 교정 및 발의 기능을 향상시킬 뿐만 아니라 체중 및 균형을 유지시키고 약화된 부위를 지지함으로써 사람의 직립자세 유지를 위한 균형 유지에 많은 도움이 된다. 이에 본 사례 연구에서는 보행 안정성을 비롯한 충격 흡수 기능을 수용할 수 있는 기능성 발보조기가 족부 형태 및 재질에 따라 신체의 균형유지에 미치는 영향에 대하여 연구하였다. 사람의 평균 무게 중심점의 흔들림 속도(sway velocity)를 이용한 균형감각 자세유지도의 고찰을 통해 족부형태별, 기능성 보조기의 재질에 따른 신체의 균형능력에 미치는 영향을 비교 평가한 결과, 안정한 상태에서 눈을 뜬 자세에서만 유의(p<0.006)한 결과를 나타냈으며, 이 자세에서 발의 형태별로 구분하여 통계 처리한 결과, 정상족(p<0.010), 편평족(p<0.000), 요족(p<0.003)의 순으로 나타났다. 그리고 기능성 발보조기의 재질에 따른 발의 형태별 균형에 미치는 영향을 분석한 결과, 연성재질은 정상의 발에서 그리고 경성재질은 편평족과 요족에 있어서 균형유지에 효과가 있는 것으로 나타났다.

• 한국전자파학회논문지
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• 제26권1호
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• pp.16-23
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• 2015

본 논문에서는 WCDMA2100 이동통신망을 사용하는 밴드형 wearable device에 적합한 bent 마이크로스트립 패치 안테나와 이를 적용하기 위한 RF configuration을 제안하였다. 제안된 안테나는 WCDMA2100 송수신 주파수 대역을 분리한 RF configuration을 사용하여 WCDMA 송신대역에서만 동작하도록 설계되었고, 후면의 도체(ground)로 인해 인체의 영향을 적게 받는다. 제안된 안테나는 flat 및 bent할 경우 모두 최대 이득은 5.3 dBi 이상, -6 dB 반사손실 대역폭은 20 MHz 이상을 가지고 전자파 인체 흡수율 시뮬레이션 $SAR_{1g}$ 0.7 [W/kg] 이하를 갖는다. 제안된 안테나는 사람의 손목이나 팔에 착용하는 밴드형 wearable device에 적합하게 사용될 수 있다.

• Ocean and Polar Research
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• 제28권3호
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• pp.215-224
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• 2006

Spatial variation of heavy metal accumulation was investigated in Manila clam Ruditapes philippinarum collected from several tidal flats. Sediment metal levels varied highly among the sites, which was attributed primarily to differences in Fe and organic carbon contents and in part to gain size. Significant differences in metal concentrations also were found in the clam tissue among the different sampling sites. However, except for a few metals (Mn, Zn, Pb), which showed some elevation, the variations in the clam tissue were not related to the variations in the sediment. This is likely because most metals in filter-feeding herbivores such as R. philippinarum accumulated as a result of feeding on suspended particles such as phytoplankton and organic detritus in the water column, not in bottom sediment. In addition, tissue weight for a specific shell size varied significantly among the sites, and increased tissue mass indicating a good nutritive condition likely caused a subsequent dilution of body metals leading to reduced weight-specific concentrations of some metals (Cd, Zn, Cu, Co).