• Ocean and Polar Research
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• 제29권3호
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• pp.217-231
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• 2007

To explore limiting factors of spring bloom caused by waste disposal after dumping activity commenced in the Yellow Sea, we used a 1-dimensional temperature-ecological coupled model. The vertical structure of temperature and vertical diffusivity (Kh) are calculated by the temperature model with sea surface temperature using the 2.5 layers turbulence closure scheme. The ecological model applied results at the temperature model consisted of five state variables (DIN, DIP, phytoplankton, zooplankton, and detritus) forced by photosynthetically available radiation. We simulate year-to-year variations of plankton and nutrients using the coupled model from 1998 to 2000 and compare results of the model with observed data. It turned out that temperature is the growth factor of spring bloom in dumping area. During the winter the weak stratification made sufficient supply of the accumulated nutrients from the sea bed into the upper water column and led to the bloom in the coming spring. Radiation also turned out to be another important factor of spring bloom in the study area. Insufficient radiation of March 1999 showed low chlorophyll-a concentration despite sufficient nutrients in the surface.

• Natural Product Sciences
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• 제6권2호
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• pp.73-78
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• 2000

The wound healing potential of the methanol extract of Hypericum mysorense Wight and Arn. Leaves (Family: Hypericaceae) was evaluated on different experimental models of wounds in rats. The methanol extract of leaves of Hypericum mysorense (HMM), in the form of ointment in two different concentrations (5% and 10% w/w ointment of aerial part extract in simple ointment base) was evaluated for wound healing potential in excision wound model and incision wound model in rats. Both the concentrations of the methanol extract ointment showed significant responses in both the wound types tested when compared with the control group. The effect produced by the extract ointment, in terms of wound contracting ability, wound closure time, regeneration of tissues at wound site, tensile strength of the wound and histopathological characteristics were comparable to those of a standard drug Nitrofurazone ointment.

• 대한기계학회논문집
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• 제15권5호
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• pp.1717-1726
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• 1991

본 연구에서는 낮은 레이놀즈수 영역에도 적용될 수 있는 레이놀즈응력모델의 개발을 위해, 우선 벽근처 영역에서 사용되는 실험식(벽법칙)을 Hassid와 Poreh에 의 해 개발된 1-방정식모델로 대체하고 이를 레이놀즈응력모델과 접속시키는 방식을 사용 하였다. Hassid-Poreh의 1-방정식모델은 이미 Gibson등에 의해 그 성능이 평가되어 압력구배가 크지 않은 경계층유동의 낮은 레이놀즈수 영역에서 매우 좋은 결과를 보여 줌이 밝혀졌다. 본 연구에서는 곡면위의 난류경계층에 대해 위에서 설명한 바 있는 난류모델을 적용함에 있어 Gillis등과 Gibson등에 의해 실험된, 각각 곡률이 큰 경우 와 작은 경우의 대표적인 유동을 선택하여 모델의 성능을 시험하였다. 1-방정식모델 내에 포함된 길이차원(length scale)에 대해서는 곡률을 고려한 수정이 이루어졌다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.20-24
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• 2011

In this paper, numerical simulation of cavitation flow for modified NACA66 hydrofoil was made by using the multi-phase RANS equation based on pseudo-compressibility. The Homogeneous mixture model comprised of the mixture continuity, mixture momentum and liquid volume fraction equations was utilized. A vertex-centered finite-volume method was used in conjunction 2nd-order Roe's FDS to discretize the inviscid fluxes. The viscous fluxes were computed based on central differencing The Spalart-Allmaras one equation model was employed for the closure of turbulence. Reasonable agreements were obtained between the calculation results and the experiment for pressure coefficients on the hydrofoil surface.

• Ocean and Polar Research
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• 제24권2호
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• pp.135-146
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• 2002

The upper ocean in the western equatorial Pacific warm pool during TOGA-COARE IMET IOP was simulated using a one-dimensional turbulence closure ocean mixed-layer model, which considered recent observations, such as the remarkable enhancement of turbulent kinetic energy near the ocean surface. The shoaling/deepening of the mixed layer and warming/cooling subsurface water in the model were in reasonable agreement with the observations. There was a significant improvement in simulating the cooling trend of the sea surface temperature under a westerly wind burst with heavy rainfall over previous simulations using bulk mixed-layer models. By contrast the simulated sea surface salinity (SSS) departed significantly from the observed SSS, especially during a westerly burst and the subsequent restratification period, which might be due to 3-D control processes, such as downwelling/upwelling or advection.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.771-776
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• 2000

Fine grid calculations are reported for the developing turbulent flow in a straight duct and a curved duct of square cross-section with a radius of curvature to hydraulic diameter ratio ${\delta}=R_c/H_H=3.357$ and a bend angle of 180 deg. A sequence of modeling refinements is introduced; the replacement of wall function by a fine mesh across the sublayer and a low Reynolds number second moment closure up to the near wall sublayer in which the non-linear return to isotropy model and the cubic-quasi-isotropy model for the pressure strain are adopted; and the introduction of a multiple source model for the exact dissipation rate equation. Each refinement is shown to lead to an appreciable improvement in the agreement between measurement and computation.

• Structural Engineering and Mechanics
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• 제5권6호
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• pp.679-689
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• 1997

The damage of concrete subjected to multiaxial complex loading involves strong anisotropy due to its highly heterogeneous nature and the geometrically anisotropic characteristic of the microcracks. A comprehensive description of concrete damage is proposed by introducing a fourth-order anisotropic damage tenser. The evolution of damage is assumed to be related to the principal components of the current states of stress and damage. The unilateral effect of damage due to the closure and opening of microcracks is taken into account by introducing projection tensors that are also determined by the current state of stress. The proposed damage model considers the different kinds of damage mechanisms that result in different failure modes and different patterns of microdefects that cause different unilateral effects. This damage model is embedded in a thermomechanically consistent constitutive equation in which hardening and the triaxial compression caused shear-enhanced compaction can also be taken into account. The validity of the proposed model is verified by comparing theoretical and experimental results of plain and steel fiber reinforced concrete subjected to complex triaxial stress histories.

• Journal of applied mathematics & informatics
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• 제40권3_4호
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• pp.531-543
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• 2022

The article proposed a new type of data relationship: Positive Boolean dependencies by groups on block and slice in the database model of block form, where instead of considering value pairs, we consider a group of p values (p ≥ 2). From this new concept, the article stated and demonstrated the equivalence of the three types of deduction, namely: deduction by logic, deduction by block with groups, deduction by block has no more than p elements with groups. Operations on blocks or slices performed for index attributes on blocks, the properties related to this new concept as theorem the equivalen of the three types of deduction, closure of set positive Boolean dependencies by groups and representation and tight representation set of positive Boolean dependencies by groups when the block degenerated into relation are true in the relational database model and also stated and proven in this paper.

• 한국공간구조학회논문집
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• 제15권1호
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• pp.75-84
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• 2015

This paper presents the dimensionless wall distance, y+ effect on SST turbulent model for wind turbine blade. The National Renewable Energy Laboratory (NREL) Phase VI wind turbine was used for the study, which the wind tunnel and structural test data has publicly available. The near wall treatment and turbulent characteristics have important role for proper CFD simulation. Most of the CFD development in this area is focused on advanced turbulence model closures including second moment closure models, and so called Low-Reynolds (low-Re) number and two-layer turbulence models. However, in many cases CFD aerodynamic predictions based on these standard models still show a large degree of uncertainty, which can be attributed to the use of the $\epsilon$-equation as the turbulence scale equation and the associated limitations of the near wall treatment. The present paper demonstrates the y+ definition effect on SST (Shear Stress Transport) turbulent model with advanced automatic near wall treatment model and Gamma theta transitional model for transition from lamina to turbulent flow using commercial ANSYS-CFX. In all cases the SST model shows to be superior, as it gives more accurate predictions and is less sensitive to grid variations.

• Journal of Pharmaceutical Investigation
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• 제40권1호
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• pp.45-49
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• 2010

Unlike human, with some exceptions, animals do not heal with excessive scar. The lack of suitable animal model has hindered the development of effective scar therapy. We previously reported that partial thickness rabbit ear wound model resembles human wound heal process. This study was designed to prepare a hypertropic scar wound model which can be employed for testing anti-scar therapy. Four wounds were created down to the bare cartilage on the anterior side of each rabbit ear using 8-mm dermal biopsy punch and histology analysis at post operation day (POD) 5, 28 and 48 were performed. As the outcome of scar formation is largely determined by the early inflammatory response to the wounding and the degree and the duration of occlusion, cephalodin(50 mg/kg) was injected daily and medical occlusive dressings were applied. Five micro wound and scar sections were stained with hematoxylin and eosin for quantification of epidermal regeneration and scar hypertrophy. Sections were also stained using Masson's trichrome and Sirius red to evaluate collagen organization and rete ridge formation. Wound closure process was assessed to 7wks post wounding. Complete removal of the epidermis, dermis and perichondrial layer caused delayed epithelialization, which results in hypertropic scarring. The inability of the wounds to contract and the delay in epithelialization in rabbit ear was likely due to cartilage and it created scar elevation. The results suggest that full thickness surgical punch wound model in rabbit ear could be employed as a reliable and reproducible scar wound model for testing anti-scar therapy.