• Journal of Ship and Ocean Technology
• /
• 제9권3호
• /
• pp.23-32
• /
• 2005

Ship STEP(Standard for the Exchange of Product Model Data) which is composed of AP 215 (Ship Arrangement), AP 216(Ship Hull Form), AP 218 (Ship Structure), has been developed more than last 10 years and it is now at the stage just before IS(International Standard). It is expected that ship STEP would be used for the seamless data exchange among various CAD/CAM/CAE systems of shipbuilding process. In this paper the huge and complicated data structure of ship STEP is briefly reviewed at the level of ARM(Application Reference Model) and some abstract test cases which will be included as part of the standards are introduced. Basically ship STEP has common data model to be used without losing compatibility among those three different ship AP's, and it is defined as the modeling framework. Typical cases of data exchange during shipbuilding process, such as hull form data exchange between design office and model basin, midship structure data between shipbuilding yard and classification society are reviewed and STEP physical data are generated using commercial geometric modeling kernel. Test cases of ship arrangement at initial design stage and hydrodynamic data of crude oil carrier are also included.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제8권4호
• /
• pp.233-239
• /
• 2003

For the quantitative analysis of an unknown sample a calibration curve should be obtained, as analytical instruments give relative, rather than absolute measurements. Therefore, researchers should make standard samples with various known concentrations, measure each standard and the unknown sample, and then determine the concentration of the unknown by comparing the measured value to those of the standards. These procedures are tedious and time-consuming. Therefore, we developed a polymer based microfluidic device from polydimethylsiloxane, which integrates serial dilution and capillary electrophoresis functions in a single device. The integrated microchip can provide a one-step analytical tool, and thus replace the complex experimental procedures. Two plastic syringes, one containing a buffer solution and the other a standard solution, were connected to two inlet holes on a microchip, and pushed by a hydrodynamic force. The standard sample is serially diluted to various concentrations through the microfluidic networks. The diluted samples are sequentially introduced through microchannels by electro-osmotic force, and their laser-induced fluorescence signals measured by capillary electrophoresis. We demonstrate the integrated microchip performance by measuring the fluorescence signals of fluorescein at various concentrations. The calibration curve obtained from the electropherograms showed the expected linearity.

• 한국환경과학회지
• /
• 제16권8호
• /
• pp.959-971
• /
• 2007

The three-dimensional eco-hydrodynamic model was applied to estimate the autochthonous COD caused by production of phytoplankton in Jinhae Bay. A residual current was simulated, using a hydrodynamic model, to have a sightly complicated pattern in the inner part of the bay, ranging from 0.001 to 5 cm/s. In the outer part of the bay, the simulated current flowed out to the south sea with a southward flow at a maximum of 25 cm/s. The results of the ecological model simulation of COD levels showed high concentrations, exceeding 4 mg/L, in the inner bay of Masan, an area of wastewater discharge, and lower levels, approaching less than 1 mg/L, closer to the outer part of the bay. The simulation results of Autochthonous COD by two methods using ecological modeling, showed high ratio over 70% of total COD. Therefore, it is more important to consider nutrients than organic matters in the region for control COD standard.

• 한국추진공학회지
• /
• 제11권5호
• /
• pp.37-50
• /
• 2007

본 연구에서는 액체 추진제 로켓엔진의 연소기에 주로 사용되는 액체 동축 스월형 분사기의 분무특성을 예측할 수 있는 모델을 개발하여 분무 연소장을 계산하기위하여 개발된 KIVA의 환경에 적합하도록 유도하였다. 액막의 분열에는 선형 안정성 이론을 도입하여 장파와 단파의 영역을 모두 고려할 수 있는 모델을 개발하였고 점성이 고려된 수력학적 해석을 통해 초기의 액막 두께와 분무각 및 분사 속도를 예측하였다. 또한 개발된 분무 모델에 대한 난류 모델의 적합성을 평가하여 RNC $k-{\varepsilon}$ 모델이 적합함을 알았다. 이러한 모델의 평가를 바탕으로 액체로켓엔진에 장착되는 분사기에서 생산되는 분무의 특성을 실험 결과와 비교하였고, 분열 길이, 분무각 및 SMD가 정성적, 정량적으로 잘 일치하는 것을 알 수 있었다.

• 천문학회보
• /
• 제44권2호
• /
• pp.48.4-48.4
• /
• 2019

We studied the metal-distribution of isolated Milky-way mass galaxy using various hydrodynamic solvers and investigated the difference of the result between AMR and SPH codes. In particle-based codes, physical quantities like mass or metallicity defined in each particle are conserved unless being injected explicitly by the effect of the supernova, whereas in the Eulerian codes the diffusion is simply accomplished by hydro-equation. Therefore, without including explicit physics of diffusion on the SPH- codes, the metal mixing in the galaxy or CGM only can be accomplished by the direct motion of the particles, however, the standard-SPH codes depress the instability of the turbulent fluid mixing. In this work, we simulated under common initial conditions, common gas-physics like cooling-heating models, and star-formation feedback using ENZO(AMR) GIZMO and GADGET-2 codes. We additionally included a metal-diffusion algorithm on the SPH-codes, which follows the subgrid-turbulent mixing model investigated by Shen et al. (2010) and compared the effect of the metal-outflow on the halo region of the galaxy in different hydro-solvers. We also found that for the implementation of the diffusion scheme in the SPH-codes, the existence of a sufficient number of the gas-particles, which is the carrier of the metals, is necessary. So we tested a new initial condition for proper implementation of the diffusion scheme on the SPH simulations. By comparing the metal-contamination of the circumgalactic medium with different hydrodynamics models, we quantify the diffusion strength of AMR codes using diffusion parameterization of the SPH codes and also suggest the calibration solutions in the different behavior of codes in metal-outflow.

• Tribology and Lubricants
• /
• 제19권3호
• /
• pp.167-177
• /
• 2003

The study deals with the development of a thermohydrodynamic (THD) computational procedure for evaluating the pressure, temperature and velocity distributions in fluid films with very rough geometry. A parametric investigation is performed to predict the bearing behaviors in the lubricating film having the absorbed layers and their interfaces determined by the rough surfaces with Gaussian distribution. The layers are expressed as functions of the standard deviations of each surface to characterize flow patterns between both the rough sur-faces. The velocity variations and the heat generation are assumed to occur in the central (shear) zone with the same bearing length and width. The coupled effect of surface roughness and shear zone dependency on hydrodynamic pressure and temperature has been found in non-contact mode. The procedure confirms the numerically determined relationship between the pressure and film gap on condition that its roughness magnitude is smaller than the fluid film thickness.

• 대한토목학회논문집
• /
• 제5권4호
• /
• pp.87-94
• /
• 1985

본 논문에서는 최근에 개발된 심해용 구조물인 guyed tower 의 동력학적 해석방법과 이의 주요 설계인자인 guying system 의 강성 및 구조물기초부에서의 회전강성이 구조물의 거동에 미치는 영향에 대하여 연구하였다. 해석기법으로는 guying system 의 초기강성을 사용하여 구한 자유진동 모우드의 중첩법을 주로 고찰하였으며, 그 결과를 몇가지의 다른방법에 의한 결과와 비교검토하였다. 예제해석은 세계최초의 guyed tower 인 Lena tower 를 표준구조물로 택하여 수행되었다.

• 한국해양공학회지
• /
• 제22권5호
• /
• pp.31-38
• /
• 2008

The numerical simulation of tsunami against the south coast of the Korean Peninsula has been performed by adopting the standard appropriate grid size and the numerical model has been constructed to include the characteristics of the tsunami propagation applied for the care of the East China Sea. The artificial tsunami has been modelled first and then, it has been used as the boundary condition for the detailed model which showed the south coast of the Korean Peninsula.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집C
• /
• pp.299-304
• /
• 2001

An approach is developed for parametric investigation of the influence of the surface roughness on thermohydrodynamic analysis with film conditions which systemically occur in journal bearings. A parametric investigation is performed for predicting the bearing behaviors such as pressure and temperature distributions in lubricating films between the stationary and moving surfaces determined by absorbed layers and interfaces on the statistical method for rough surface with Gaussian distribution. The layers expressing the effects of surface roughness are expressed as functions of the standard deviations (${\sigma}$) of each surface and surface orientation (j) to explain the flow patterns between both rough surfaces. The coupled effect of surface roughness and shear zone dependency on hydrodynamic pressure and temperature has been found by solving the present model in non-contact mode and contact mode, respectively.

• 환경영향평가
• /
• 제20권1호
• /
• pp.37-48
• /
• 2011

Recently, the social and environmental functions of nature river are important due to the increase of expectation for river restoration. So it should be considered the effect of vegetation affecting the conveyance capacity and hydraulic resistance. However, it has not yet proposed a objective standard and modeling method to estimate the effect of conveyance capacity according to vegetaion distribution in the watercourse such as water level or velocity. Therefore, this study simulates the variations of water level and velocity using 3-dimensional hydrodynamic model, EFDC, to consider a conveyance capacity in downstream of the Soyang Reservoir. The simulation results were validated using statistical index such as F-test and T-test. As results, the water level rises about 0.01 to 0.47m and velocity difference are about -0.95m/s to 0.23m/s.