• Title/Summary/Keyword: impermeable

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The Water Wave Scattering by the Marine Structure of Arbitrary Shape (임의 형태의 해양구조물에 의한 해수파의 산란)

  • 신승호;이중우
    • Journal of the Korean Institute of Navigation
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    • v.17 no.1
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    • pp.61-78
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    • 1993
  • Large offshore structure are to be considered for oil storage facilities , marine terminals, power plants, offshore airports, industrial complexes and recreational facilities. Some of them have already been constructed. Some of the envisioned structures will be of the artificial-island type, in which the bulk of structures may act as significant barriers to normal waves and the prediction of the wave intensity will be of importance for design of structure. The present study deals wave scattering problem combining reflection and diffraction of waves due to the shape of the impermeable rigid upright structure, subject to the excitation of a plane simple harmonic wave coming from infinity. In this study, a finite difference technique for the numerical solution is applied to the boundary integral equation obtained for wave potential. The numerical solution is verified with the analytic solution. The model is applied to various structures, such as the detached breakwater (3L${\times}$0.1L), bird-type breakwater(318L${\times}$0.17L), cylinder-type and crescent -type structure (2.89L${\times}$0.6L, 0.8L${\times}$0.26L).The result are presented in wave height amplification factors and wave height diagram. Also, the amplification factors across the structure or 1 or 2 wavelengths away from the structure are compared with each given case. From the numerical simulation for the various boundary types of structure, we could figure out the transformation pattern of waves and predict the waves and predict the wave intensity in the vicinity of large artificial structures.

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Linear Stability of Compositional Convection in a Mushy Layer during Solidification of Ammonium Chloride Solution (염화암모늄 수용액 응고시에 Mush 층에서 성분적 대류의 선형안정성)

  • Hwang, In Gook
    • Korean Chemical Engineering Research
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    • v.50 no.1
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    • pp.61-65
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    • 2012
  • The onset of convection in a mushy layer is analyzed by using linear stability theory in time-dependent solidification of a binary melt. A simplified model of a near-eutectic mush, in which the mush is assumed to be a porous block, is used and the propagation theory is applied to determine the critical conditions for the onset of convection. The present critical Rayleigh number is higher than the existing experimental result and also theoretical results obtained by considering the mushy layer with an overlying liquid layer. The constant pressure (permeable) condition applied on the mush-liquid interface produces a lower critical Rayleigh number, which is closer to the experimental results of aqueous ammonium chloride solution, compared with the impermeable condition.

Protein Drug Oral Delivery: The Recent Progress

  • Lee, Hye-J.
    • Archives of Pharmacal Research
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    • v.25 no.5
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    • pp.572-584
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    • 2002
  • Rapid development in molecular biology and recent advancement in recombinant technology increase identification and commercialization of potential protein drugs. Traditional forms of administrations for the peptide and protein drugs often rely on their parenteral injection, since the bioavailability of these therapeutic agents is poor when administered nonparenterally. Tremendous efforts by numerous investigators in the world have been put to improve protein formulations and as a result, a few successful formulations have been developed including sustained-release human growth hormone. For a promising protein delivery technology, efficacy and safety are the first requirement to meet. However, these systems still require periodic injection and increase the incidence of patient compliance. The development of an oral dosage form that improves the absorption of peptide and especially protein drugs is the most desirable formulation but one of the greatest challenges in the pharmaceutical field. The major barriers to developing oral formulations for peptides and proteins are metabolic enzymes and impermeable mucosal tissues in the intestine. Furthermore, chemical and conformational instability of protein drugs is not a small issue in protein pharmaceuticals. Conventional pharmaceutical approaches to address these barriers, which have been successful with traditional organic drug molecules, have not been effective for peptide and protein formulations. It is likely that effective oral formulations for peptides and proteins will remain highly compound specific. A number of innovative oral drug delivery approaches have been recently developed, including the drug entrapment within small vesicles or their passage through the intestinal paracellular pathway. This review provides a summary of the novel approaches currently in progress in the protein oral delivery followed by factors affecting protein oral absorption.

Effects of Rain Gardens on Removal of Urban Non-point Source Pollutants under Experimental Conditions (실험실 조건에서 레인가든의 도시 비점오염물질 제거효과)

  • Kim, Changsoo;Sung, Kijune
    • Journal of Korean Society on Water Environment
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    • v.28 no.5
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    • pp.676-685
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    • 2012
  • As impermeable layer continues to increase with the urbanization process, direct input of nonpoint source pollutants into water bodies via stormwater has caused serious effects on the aquatic ecosystem. Potential applications of rain gardens are increasing not only as best management practices (BMP) for reducing the level of nonpoint source pollutants but also as an ecological engineering alternative for low impact development (LID). In this study, remediation performance of various planting types, such as a mixed planting system with shrubs and herbaceous plants, was assessed quantitatively to effectively manage stormwater and increase landscape applicability. The mixed planting system with Rhododendron lateritium and Zoysia japonica showed the highest removal performance of $76.9{\pm}7.6%$ and $58.4{\pm}5.0%$ for total nitrogen and $89.9{\pm}7.9%$ and $82.4{\pm}5.2%$ for total phosphorus at rainfall intensities of 2.5 mm/h and 5.0 mm/h, respectively. The mixed planting system also showed the highest removal performance for heavy metals. The results suggest that a rain garden with the mixed planting system has high potential applicability as a natural reduction system for nonpoint source pollutants in order to manage stormwater with low concentrations of pollutants and will increase water recycling in urban areas.

열수변질 점토맥과 산사태

  • Jo, Hwan-Ju;Jeong, Gyeong-Mun;Jo, Ho-Yeong
    • Mineral and Industry
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    • v.29
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    • pp.56-66
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    • 2016
  • In Korea, where hydrothermal alteration zones are widely distributed, clay veins formed by hydrothermal alteration processes on natural slopes or artificial slopes can play an important role in the slope stability. When the surface water infiltrates the ground where the clay vein exists, the pore water pressure in the ground can be locally increased due to impermeable properties of clay minerals. Infiltration of the surface water induces the increase in the pore water pressure, which can cause erosion of the fine clay particles. The eroded clay particles flow and deposit in an area where the flow velocity is slowed down. Where clay minerals are deposited, ground water can leak due to an increase in local pore pressures, which can cause slope failure. In this paper, studies related to hydrothermal clay vein and landslide are introduced.

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A Study of the Numerical Model on the Interaction between Irregular Waves and Permeable Coastal Structures (투수성해안구조물과 불규칙파의 상호작용에 관한 수치모델 연구)

  • 김종욱;남인식;윤한삼;류청로
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2001.05a
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    • pp.186-195
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    • 2001
  • The purpose of this study is to develop the time-dependent, one-dimensional numerical model on the interaction between irregular waves and two-layer permeable coastal structures, by extending and modifying the numerical model PBREAK(Wurjanto and Kobayashi, 1992) which is applicable only to one-layer permeable coastal structures. The two-layer permeable coastal structure consists of two permeable underlayers with different permeable media resting on an impermeable slope and an armor layer covering the permeable underlayer. The numerical model of this study simulates the wave over rough permeable underlayer of arbitrary geometry as well as the waves inside two-permeable underlayers of arbitrary thickness for specified normally-incident irregular waves. The utility of the numerical model is founded from comparing with PBREAK and the four hydraulic model tests under irregular waves. The sensitivities of computed results according to typical parameters(porosity, stone diameter, horizontal width of the permeable underlayer) and major factors(friction factor of primary armor layer etc.) discussed.

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Modification of Bouwer and Rice method using flow net to evaluate hydraulic conductivity of vertical cutoff wall considering filter cake development (연직차수벽에서 필터케익을 고려한 순간 변위시험 해석시 유선망을 이용한 수정 Bouwer and Rice법의 적용)

  • Nguyen, The Bao;Kwak, Tae-Hoon;An, Yong-Hoon;Choi, Hang-Seok
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.1478-1486
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    • 2009
  • As a conventional line-fitting method, the Bouwer and Rice method has been popularly adopted to estimate the hydraulic conductivity of an aquifer through a slug test. Because a ventical cutoff wall is usually very compressible and features a small wall thickness, the Bouwer and Rice method should be carefully used for the vertical cutoff wall. In addition, a relatively impermeable layer, called a filter cake, formed at the interface between the cutoff wall and the natural soil formation makes it difficult to use the Bouwer and Rice method directly. In order to overcome such limitations, the original Bouwer and Rice method is modified by incorporating the concept of the flow net method. In this modification, the geometry condition of cutoff walls including the filter cake is effectively considered in evaluating the hydraulic conductivity of a vertical cutoff wall.

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Plane strain consolidation of a compressible clay stratum by surface loads

  • Rani, Sunita;Puri, Manoj;Singh, Sarva Jit
    • Geomechanics and Engineering
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    • v.7 no.4
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    • pp.355-374
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    • 2014
  • An analytical solution of the fully coupled system of equations governing the plane strain deformation of a poroelastic medium with anisotropic permeability and compressible fluid and solid constituents is obtained. This solution is used to study the consolidation of a poroelastic clay layer with free permeable surface resting on a rough-rigid permeable or impermeable base. The stresses and the pore pressure are taken as the basic state variables. Displacements are obtained by integrating the coupled constitutive relations. The case of normal surface loading is discussed in detail. The solution is obtained in the Laplace-Fourier domain. Two integrations are required to obtain the solution in the space-time domain which are evaluated numerically for normal strip loading. Consolidation of the clay layer and diffusion of pore pressure is studied for both the bases. It is found that the time settlement is accelerated by the permeability of the base. Initially, the pore pressure is not affected by the permeability of the base, but has a significant effect, as we move towards the bottom of the layer. Also, anisotropy in permeability and compressibilities of constituents of the poroelastic medium have a significant effect on the consolidation of the clay layer.

Block and Extraction of Wave Energy Using a Rolling Porous Pendulum Plate (횡 방향으로 운동하는 투과성 진자판을 이용한 파랑에너지 차단과 추출)

  • Cho, Il-Hyoung
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.30 no.4
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    • pp.180-190
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    • 2018
  • The preliminary study was carried out to utilize the rolling porous pendulum plate as a hybrid system combining blocking and extracting of wave energy. The Galerkin method suggested by Porter and Evans (1995) was used to solve the diffraction and radiation problems to obtain reflection and transmission coefficient, roll displacement, extracted power. The Galerkin method provides better convergence than the matched eigenfunction expansion method (MEEM), which improves the accuracy of the analytical solution even if the CPU time is shorter. The porous plate can not be said to be more effective than the impermeable plate in terms of wave energy extraction and wave blocking, but it has the advantage of reducing the wave load and exchanging seawater.

Mapping and Analyzing the Park Cooling Intensity in Mitigation of Urban Heat Island Effect in Lahore, Pakistan

  • Hanif, Aysha;Nasar-u-Minallah, Muhammad;Zia, Sahar;Ashraf, Iqra
    • Korean Journal of Remote Sensing
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    • v.38 no.1
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    • pp.127-137
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    • 2022
  • Urban Heat Island (UHI) effect has been widely studied as a global concern of the 21st century. Heat generation from urban built-up structures and anthropogenic heat sources are the main factors to create UHIs. Unfortunately, both factors are expanding rapidly in Lahore and accelerating UHI effects. The effects of UHI are expanding with the expansion of impermeable surfaces towards urban green areas. Therefore, this study was arranged to analyze the role of urban cooling intensity in reducing urban heat island effects. For this purpose, 15 parks were selected to analyze their effects on the land surface temperature (LST) of Lahore. The study obtained two images of Landsat-8 based on seasons: the first of June-2018 for summer and the second of November-2018 for winter. The LST of the study area was calculated using the radiative transfer equation (RTE) method. The results show that the theme parks have the largest cooling effect while the linear parks have the lowest. The mean park LST and PCI of the samples are also positively correlated with the fractional vegetation cover (FVC) and normalized difference water index (NDWI). So, it is concluded that urban parks play a positive role in reducing and mitigating LST and UHI effects. Therefore, it is suggested that the increase of vegetation cover should be used to develop impervious surfaces and sustainable landscape planning.