• Journal of Ocean Engineering and Technology
• /
• v.9 no.2
• /
• pp.75-82
• /
• 1995

The free surface effects on the aerodynamic performance of 2-D wings are investigated based on the potential flow approximation. The wing is represented b source and vortex distributions on the wing surface. The steady free surface effect is taken into account by source distribution on the free surface and the velocity potentials of air and water flows are obtained. Using three different techniques, namely, positive image method, inverse image method and source distribution method, numerical results are obtained for wave elevation, pressure distribution and lift coefficient with various foil sections. The wave elevation calculated by the inverse image method is shown to be very small even at higher speeds so that the free surface effect on the performance of wings is regraded negligible. However, the wave elevations by the positive image method and source distribution method are relatively high at higher speeds and accordingly the free surface effects on wings can not be neglected.

• Journal of Industrial Technology
• /
• v.31 no.B
• /
• pp.91-98
• /
• 2011

In this thesis, from the results of settlement measurement performed at the site where embankment earthwork was carried out on the ground consisting of highly plastic and silty soft soils interlayered with organic deposits, various methods of predicting the embankment settlement such as Hoshino's method, Asaoka's method, hyperbolic method, ${\sqrt{s}}$ method and Monden's method were used to investigate their applicability and the inverse method of finding the soil parameter related to consolidation was used to predict the consolidation behavior in the future. It was confirmed that reliable prediction of consolidation behavior under various conditions could be done to estimate soil parameter related to consolidation such as the consolidation index and consolidation coefficient by the inverse method of comparing the measured settlement with the predicted value by the settlement prediction methods.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.719-723
• /
• 2002

The purpose of this study is to suggest the correlation of single-number ratings for sound insulation by floor impact. As a assessment method of impact sound insulation. we selected the IIC contour of ISO, A weighted sound level. Inverse A-weighting curve and L-Index of japanese industrial standard. And we estimated the single-number ratings by application the measured data of impact sound level to each method. The results showed that the coefficients of determination between each two single-number ratings were very high (more than 0.9169). And In the condition of same assessment method, the coefficient of determination for light-weight impact sound was higher than that for heavy-weight impact sound.

• Journal of Korean Association for Spatial Structures
• /
• v.3 no.2 s.8
• /
• pp.101-107
• /
• 2003

There exists a structural problem for link structures in the unstable state. The primary characteristics of this problem are in the existence of rigid body displacements without strain, and in the possibility of the introduction of prestressing to change an unstable state into a stable state. When we make local linearized incremental equations in order to obtain knowledge about these unstable structures, the determinant of the coefficient matrices is zero, so that we face a numerically unstable situation. This is similar to the situation in the stability problem. To avoid such a difficult situation, in this paper a simple and straightforward method was presented by means of the generalized inverse for the numerical analysis of stability problem.

• Transactions of Materials Processing
• /
• v.13 no.5
• /
• pp.441-448
• /
• 2004

Heat treatment is one of the critical manufacturing processes that determine the quality of a product. This paper presents experimental and analytical results for the quench of a ring gear in stagnant oil. The goal of this study is to develop heat transfer predicting model in an overall analysis of the quenching process, Thermal conductivities which are dependant on temperatures and convection coefficients which are obtained by inverse method are used to develop the accurate heat transfer model. The results of heat transfer model have a good agreement with experimental results.

• Journal of IKEEE
• /
• v.24 no.4
• /
• pp.982-990
• /
• 2020

Groundwater is essential source of the freshwater. Groundwater is stored in the body of the rocks or sediments, called aquifer. Finding an aquifer is a very important part of the geophysical survey. The best method to find the aquifer is to make a borehole. Single borehole is not a suitable method if the aquifer is not located in the borehole drilled area. To overcome this problem, a cross borehole method is used. Using a cross borehole method, we can estimate aquifer location more precisely. Electrical impedance tomography is use to estimate the aquifer location inside the subsurface using the cross borehole method. Electrodes are placed inside each boreholes and area between these boreholes are analysed. An aquifer is a non-uniform structure with complex shape which can represented by the truncated Fourier series. Deep neural network is evaluated as an inverse problem solver for estimating the aquifer boundary coefficients.

• Korean Chemical Engineering Research
• /
• v.46 no.3
• /
• pp.451-464
• /
• 2008

Three-phase inverse fluidized bed has been widely adopted with its increasing demand in the fields of bioreactor, fermentation process, wastewater treatment process, absorption and adsorption processes, where the fluidized or suspended particles are small or lower density comparing with that of continuous liquid phase, since the particles are frequently substrate, contacting medium or catalyst carrier. However, there has been little attention on the three-phase inverse fluidized beds even on the hydrodynamics. Needless to say, the information on the hydrodynamics and transport phenomena such as heat and mass transfer in the inverse fluidized beds has been essential for the operation, design and scale-up of various reactors and processes which are employing the three-phase inverse beds. In the present article, thus, the information on the three-phase inverse fluidized beds has been summarized and reorganized to suggest a pre-requisite knowledge for the field work in a sense of engineering point of view. The article is composed of three parts; hydrodynamics, heat and mass transfer characteristics of three-phase inverse fluidized beds. Effects of operating variables on the phase holdup, bubble properties and particle fluctuating frequency and dispersion were discussed in the section of hydrodynamics; effects of operating variables on the heat transfer coefficient and on the heat transfer model were discussed in the section of heat transfer characteristics ; and in the section of mass transfer characteristics, effects of operating variables on the liquid axial dispersion and volumetric liquid phase mass transfer coefficient were examined. In each section, correlations to predict the hydrodynamic characteristics such as minimum fluidization velocity, phase holdup, bubble properties and particle fluctuating frequency and dispersion and heat and mass transfer coefficients were suggested. And finally suggestions have been made for the future study for the application of three-phase inverse fluidized bed in several available fields to meet the increasing demands of this system.

• Journal of Educational Research in Mathematics
• /
• v.26 no.3
• /
• pp.403-420
• /
• 2016

Some of the critical changes in the revised 2015 Korean Mathematics curriculum were that direct proportion and inverse proportion were moved from elementary school to middle school and that supplementary content related to correlation was included. These decisions were based on comparative studies of international curriculum. Therefore in this study, we selected countries for comparison; United States, England, France, Finland, Australia, Japan, Singapore, China and Taiwan. We looked into the timing and scope for direct/inverse proportion and correlation in curricula of these countries. Along with this, we established four criteria; vertical sequence, horizontal sequence, external connection, and internal connection for an analysis framework. Then we compared and analysed the direct/inverse proportion and correlation in each curriculum. As a result, in most of these curricula, the direct/inverse proportions are introduced at middle school or are introduced at elementary school and then developed further at middle school. Most of curriculums on direct/inverse proportion and correlation match the four criteria. Correlation is introduced in high school mathematics in all counties except Finland and it is dealt in diverse context introducing related concepts, for example, correlation coefficient, regression straight line, and least square. We suggested that it is necessary to refer these international trends for the next revision of curriculum.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.17 no.3
• /
• pp.149-157
• /
• 2005

Typical water quality (WQ) parameters defined in the governing equation of the WQ model are the pollutant loads from atmosphere and watersheds, pollutant release rates from sediment, diffusion coefficient and reaction coefficient etc. The direct measurement of these parameters is very difficult as well as requires high cost. In this study, the pollutant budget equation including these parameters was used to construct the linear simultaneous equations. Based on these equations, the inverse problems were constructed and WQ parameter estimation method minimizing the sum of squared errors between the computed and observed amounts of the mass changes was suggested. WQ parameters, i.e., the atmospheric pollutant loads, sediment release rates, diffusion coefficients and reaction coefficient, were estimated using .this method by utilizing the vertical concentration profile data which has been observed in Cheonsu Bay and Ulsan Port. Values of the estimated parameters show a large temporal variation. However, this technique is persuasive in that the RHS (root mean square) error was less than $5.0\%$ of the observed value ranges and the agreement index was greater than 0.95.

• Fire Science and Engineering
• /
• v.27 no.6
• /
• pp.15-20
• /
• 2013

The convective heat transfer coefficient, emissivity, and flame heat flux on the surface of Duglas fir are estimated by using repulsive particle swarm optimization. The surface temperature, mass loss rate, and ignition time are measured for various incident heat fluxes from a cone heater of the cone calorimeter. The calculated surface temperatures obtained by using the optimized convective heat transfer coefficient, emissivity and flame heat flux on the surface in this study match well with those obtained from the test. The maximum error between the predicted and measured surface temperatures for the three different external heat fluxes is within 2% showing reasonable agreements. The methodology proposed in this study can be used to obtain various values related to heat transfer on a flaming surface that are difficult to measure in experiments.