• Title/Summary/Keyword: Media Flow

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산악지역 내 LNAPL 오염의 개념모델 정립을 위한 사례연구

  • Kang, U-Jae;Gong, Jun;Jeon, Jin-Oh;Lee, Sang-Bong;Hwang, Jong-Sik;Bae, U-Geun
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2001.04a
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    • pp.85-88
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    • 2001
  • Since mountainous area has access restrictions for field work, assessors need to establish a conceptual model of the contamination prior to the field investigation. In this study we established a conceptual model of the contamination based on site inspection and geological survey, followed by the field investigation for the petroleum spill site. In the conceptual model, we estimated that tile contamination should have spread by groundwater and topographical characteristics within the top soil layer. The spread of contamination through rock was not considered in the conceptual model due to impermeable characteristics of metasyenite. The contaminated environmental media of the petroleum spill site include soil and groundwater. According to the analysis result of the contamination, the volume of contaminated soil is estimated approximately 4, 150 cubic meters (7, 055 ton) with most contaminants existing along the groundwater flow within top soil layer.

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Development of bearing/sealing test facility for turbopump system (터보펌프 시스템용 베어링/실 시험설비 개발)

  • 우관제;김경호;우유철
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2003.10a
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    • pp.25-28
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    • 2003
  • The bearing/sealing test (BST) facility is intended for tests of bearing and seal for turbopump of liquid rocket engine (LRE) in various media (water, liquid nitrogen, liquid oxygen). The bearing test for serviceability is fulfilled with the estimation of the flow rate of cooling medium through the test bearing separator and with the simulation of axial and(or) radial loading. The purpose of seals test is the determination of magnitude of leakages through the seal and a time variation of this magnitude.

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Organic Pollutant Transport in Unsaturated Porous Media by Atmospheric Breathing Process(II) Dispersion Coefficient (불포화토양에서 확산에 의한 유기오염물질의 이동)

  • 구자공;황종혁
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 1997.05a
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    • pp.79-82
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    • 1997
  • 토양내에서 오염유기물질이 불포화토양내에 유입될 때의 dispersion coefficient를 adsorption과 desorption과정에 대해 알아보았다. apparent dispersion coefficient를 측정하기 위해 일상적인 상대습도(46%)조건에서 parametric analysis를 행하였다. 실험에 사용된 토양은 fine sand와 silt-clay혼합시료였고, 흐름방향은 상향과 하향으로 하였다. 그리고, Freon gas를adsorbing solute로 사용하였다. 오염물질로는 DCM, TCE, DCB를 사용하였다. 분석을 위해서 linear와 probability scale의 breakthrough curve를 사용하였다. 공기에서의 diffusion coefficient의 예측을 위하여 Graham's law를 계산에 사용하였고, DCM diffusion coefficient는 0.098$\textrm{cm}^2$/s로 계산되었다. 연구결과, adsorption과 desorption의 속도는 차이가 있는 것으로 나타났으며, diffusion이 flow regime을 좌우하는 것으로 나타났다. 그리고, desorption에서의 D$^{a}$ D$^{o}$ 는 1보다 클수도 있다. 또한, dispersion은 silt-clay혼합시료에서의 속도와 함께 증가한다. dispersion은 Freon의 sorption방향에 크게 의존한다.

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Numerical study on heat transfer and densification for SiC composites during thermal gradient chemical vapour infiltration process

  • Ramadan, Zaher;Im, Ik-Tae
    • Carbon letters
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    • v.25
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    • pp.25-32
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    • 2018
  • In this study, a thermal-gradient chemical vapor infiltration (TG-CVI) process was numerically studied in order to enhance the deposition uniformity within the preform. The computational fluid dynamics technique was used to solve the governing equations for heat transfer and gas flow during the TG-CVI process for two- and three-dimensional (2-D and 3-D) models. The temperature profiles in the 2-D and 3-D models showed good agreement with each other and with the experimental results. The densification process was investigated in a 2-D axisymmetric model. Computation results showed the distribution of the SiC deposition rate within the preform. The results also showed that using two-zone heater gave better deposition uniformity.

크로마토그라피를 이용한 당에스테르의 분리정제

  • Jo, Jeong-Yeon;Kim, Jae-Hun;Yu, In-Sang;Yu, Hyeon-Hui
    • 한국생물공학회:학술대회논문집
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    • 2000.11a
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    • pp.630-631
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    • 2000
  • Sugar esters are produced by transesterification of fatty acids and sugars in organic solvent media. Chromatographic separation of sugar esters and fatty acids was investigated. $C_{18}$ column($3.9{\times}300mm$) was used in the chromatography experiment. The effect of flow rate, column temperature, and sample loading on the charateristics of chromatogram was studied. Sugar esters and fatty acids tested in this study was successfully separated with a high resolution.

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Molecular Dynamics Simulations of Fullerene Nanostructure Fabrications by Atomic Force Microscope Carbon Nanotube tip (원자간력 현미경 탄소 나노튜브 팁을 이용한 플러렌 나노 구조물 제작에 관한 분자동역학 시뮬레이션)

  • 이준하;이홍주
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.8
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    • pp.812-822
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    • 2004
  • This paper shows that carbon nanotubes can be applied to a nanopipette. Nano space in atomic force microscope multi-wall carbon nanotube tips is filled with molecules and atoms with charges and then, the tips can be applied to nanopipette when the encapsulated media flow off under applying electrostatic forces. Since the nano space inside the tips can be refilled, the tips can be permanently used in ideal conditions of no chemical reaction and no mechanical deformation. Molecular dynamics simulations for nanopipette applications demonstrated the possibility of nano-lithography or single-metallofullerene-transistor array fabrication.

A Numerical Study of Wave Transformation on a Permeable Structure Considering Porous Media Flow (투수층의 흐름을 고려한 투수성 구조물의 파랑변형에 관한 수치적 해석)

  • Kim, In-Chul
    • Journal of Ocean Engineering and Technology
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    • v.20 no.6 s.73
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    • pp.35-40
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    • 2006
  • In recent years, there's been strong demand for seawalls that havea gentle slope and permeability that serveswater affinity and disaster prevention from wave attack. The aim of this study is to examine wave transformation, including wave run-up that propagates on the coastal structures. A numerical model based on the weak nonlinear dispersive Boussinesq equation, together with the unsteady nonlinear Darcy law for fluid motion in permeable layer, is developed. The applicability of this numerical model is examined through Deguchi and Moriwaki's hydraulic model test on the permeable slopes. From this study, it is found that the proposed numerical model can predict wave transformation and run-up on the gentle slope with a permeable layer, but can't show accurate results for slopes steeper than about 1:10.

Effect of Particle Contamination on Objective Lens in a CD-ROM Drive on Laser Diode Power and Photo Diode RF Signal (CD-ROM 드라이브의 대물렌즈 입자오염이 Laser Diode의 Power와 Photo Diode의 RF Signal에 미치는 영향)

  • Pae, Yang-Il;Hwang, Jung-Ho
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1429-1434
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    • 2003
  • A number of dust particles are intruded into ODD(Optical disk drive) due to the flow caused by disk rotation and are adhered to a lens or disk surface. The space between the disk and the lens is being reduced. Someone indicates the problems of this drive that are relatively small data storing capacity and slow access time. In recent, the problems of this optical disk drive mentioned above are being solved by adding the speed of the disk's revolution, making the actuator high-speed or light, and making the beam spot size smaller than making the space narrow between disk and lens. These particle contamination affects seriously RF Signal, readout signal in an ODD. Especially, the affected parts by a particle contamination in an ODD's readout signal are objective lens and media.

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Surgical Resection of the Aneurysm of the Thoracic Aorta: Report of A Case (흉부대동맥의 동맥류 절제 치험례)

  • 김영태
    • Journal of Chest Surgery
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    • v.6 no.1
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    • pp.51-56
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    • 1973
  • This is one case report of successful resection of the aneurysm of the thoracic aorta, which det-ected by thoractomy unexpectedly, in the Department of Thoracic Surgery, Hanyang University Hospital. The patient was a 34 years old woman and subjective complaints was not related with the aneurysm. Chest film showed a small round hazy shadow in the left margin of the upper posterior mediastinum. A saccular aneurysm located on the descending thoracic aorta, 7cm distal to the left subclavian artery and arouse from the antero-lateral wall of the aorta. Excision of the saccular aneurysm was performed by cross clamping the descending aorta above and below the aneurysm, and then the defect of the aortic wall was closed by aortorrhaphy with continuous suture. Crossclamping time was required 15 minute. Histopathologically, the wall of the aneurysm consisted of all layers of the arterial wall, that is, intima, media and adventitia. Postoperative course was uneventful and aortogram showed good continuity of the blood flow of the entire aorta.

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Electro-osmotic pump in osteo-articular tissue engineering: A feasibility study

  • Lemonnier, Sarah;Naili, Salah;Lemaire, Thibault
    • Advances in biomechanics and applications
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    • v.1 no.4
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    • pp.227-237
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    • 2014
  • The in vitro construction of osteo-articular large implants combining biomaterials and cells is of great interest since these tissues have limited regeneration capability. But the development of such organoids is particularly challenging, especially in the later time of the culture, when the extracellular matrix has almost filled the initial porous network. The fluid flow needed to efficiently perfuse the sample can then not be achieved using only the hydraulic driving force. In this paper, we investigate the interest of using an electric field to promote mass transport through the scaffold at the late stage of the culture. Based on the resolution of the electrokinetics equations, this study provides an estimation of the necessary electric driving force to reach a sufficient oxygen perfusion through the sample, thus analyzing the feasibility of this concept. The possible consequences of such electric fields on cellular activities are then discussed.