• Journal of Environmental Policy
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• v.5 no.2
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• pp.1-26
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• 2006

This paper reveals Material Flow Analysis(MFA) has the possibility of reconciling the two contending theoretical viewpoints(weak sustainability v.s. strong sustainability) and thereby makes the concept of sustainability useful at operational level. For this purpose, this paper shows that the theoretical logic of MFA can be applied from national level to product level (EW-MFA, PIOT/NAMEA, LCI), and investigates the meanings and policy implications of MFA at each level.

• Journal of Environmental Science International
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• v.5 no.6
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• pp.713-718
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• 1996

We identified two characteristic turbulent flow cases, weakening and strengthening, which appear at the downwind side. Observations were made two times, Dec. 2-3. 1995 and Feb. 13-14. 1996 at Pusan National University site located downwind side of Kumjeong mountain. Meteorological observation system, tethersonde, was adopted to present observation. In the case of the west wind which blows perpendicular to Sanghak mountain located westward from the site, the wind speed highly increased in exponential with height. Therefore, the low level wind speed was so weak just like Taylor(1988)'s review. While the wind speed was intensified at 200-400m layer when the northwest wind blows from the continental Siberian high. We suppose 기 is because of the strong vertical convergence of flow between the surface inversion layer and the upper one, and also the horizontal convergence along the saddle and valley between the two mountains, Kumjeong and Sanghak-because of Bernoulli's effect. The inversion layer existed at surface-l00m and 500-600m level and the strong wind existed at about 200-400m layer.

• Tribology and Lubricants
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• v.17 no.3
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• pp.198-208
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• 2001

A Parametric study based on a computer analysis of the lubrication system of a four-cylinder gasoline engine is illustrated. Through the parametric study, the effects of various aeration levels on the change of oil flow rate and pressure are investigated. Also, at high oil temperature and low engine speed, the effect of oil aeration level on oil flow characteristics in lubrication system is investigated. The illustrated results may give to designers the guide lines of oil aeration level for the safe design of engine lubrication systems in terms of minimum pressure at crank oil bore.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.6-9
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• 2011

In this study, the two-phase incompressible flow in two-dimensional channel considering the effect of surface tension is simulated using an improved level-set method. Quadratic element is used for solving the continuity and Navier-Stokes equations to avoid using an additional pressure equation, and Crank-Nicholson scheme and linear element are used for solving the advection equation of the level set function. Direct approach method using geometric information is implemented instead of the hyperbolic-type partial differential equation for the reinitializing the level set function. The benchmark test case considers various arrays of defomable droplets under different flow conditions in straight channel. The deformation and migration of the droplets are computed and the results are compared very well with the existing studies.

• Journal of Ship and Ocean Technology
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• v.6 no.2
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• pp.37-50
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• 2002

In the present numerical simulation of viscous free surface flow around a ship, two-fluids in-compressible Reynolds-averaged Navier-Stokes equations with the standard $\textsc{k}-\varepsilon$turbulence model are discretized on a regular grid by using a finite volume method. A local level-set method is introduced for capturing the free surface movement and the influence of the viscous layer and dynamic boundary condition of the free surface are implicitly considered. Partial differential equations in the level-set method are discretized with second order ENO scheme and explicit Euler scheme in the space and time integration, respectively. The computational results for the Series-60 model with $C_B=0.6$ show a good agreement with the experimental data, but more validation studies for commercial complicated hull forms are necessary.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.180-187
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• 2017

Major design targets such as test cell type, cell flow, cell bypass ratio, approach velocity, cell depression, front cell distortion, noise level and vibration level to construct a new 150,000 lbf thrust aircraft engine test facility were established. Based on the final aerodynamic and acoustic performance tests conducted at the newly constructed test facility, it was found that the new test facility is judged to be excellent and meets design targets.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.86.5-86
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• 2001

This work describes a design and implementation of the level & flow rate control system by using a single-chip microcontroller. The proposed model system is designed based on the use of the single-chip microcontroller 8031 with the EPROM emulator for programming the computer software. The microcontroller reaches the input level and flow signals from the level sensor and the turbine flowmeter, respectively, via the signal conditioning circuits and A/D converters in order to calculate the control signal. Moreover, the status of the process variable can easily be set up and controlled by program monitoring through the emulator, and can be graphically displayed on the computer screen. Experiment results were carried out which can be ...

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.819-822
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• 2003

This paper defines an algorithmic description language in cycle-accurate level which can be used to design hardware components. The proposed language is less complex and more flexible than VHDL language. In that the language includes C-like control flow descriptions and brief timing information(i.e. clock cycle boundaries) indicated by 'wait_edge' statements. We generate RTL VHDL codes from the descriptions. The proposed language requires only 10～30% of the # of lines to describe the same functionality compared with RTL VHDL.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.4
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• pp.487-493
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• 2003

More reliable design of thermal transport. Power acquisition and thermal management systems requires the through understanding of the flow hydrodynamic. the differences and similarities between the two-phase flow characteristics of two-Phase flow influenced by the gravity levels. The data of flow Patterns, void fraction, frictional pressure drop associated with their characteristics were obtained at $\mu\textrm{g}$. 1g and 2g. Flow patterns and void fraction data obtained at three gravity levels were compared with each other and previous models and correlations.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1313-1320
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• 1993

Flow patterns inside the riser section and the effects of the heater inlet-and exit-restrictions, liquid charging level and the heater inlet subcooling on the flow characteristics inside an open two-phase natural circulation loop were studied experimentally. Three basic circulation modes were observed ; periodic circulation (A)(flow oscillations with incubation(no boiling) period), continuous circulations(stable operation mode with no flow oscillations), and periodic circulation (B) (flow oscillations with continuous boiling). The circulation rate increases and then decreases with the increase of the heating rate and the maximum circulation rate appears with the continuous circulation mode. The decrease of the inlet-restriction or the increase of the exitrestriction destabilizes the system. When the liquid charging level or the inlet subcooling decreases, the continuous circulation mode starts at the lower heating rate and the system is stabilized.