• Journal of Korean Society on Water Environment
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• v.21 no.3
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• pp.230-235
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• 2005

The main purpose of the flocculation process is to make flocs bigger to be removed easily in the following processes. The flow pattern and mixing intensity have a great influence on flocculation. In this study, the flow pattern was examined by a hydraulic tracer-test, where 3 water treatment plants having $800,000m^3/d$, $44,000m^3/d$ and $40,000m^3/d$ were employed. Also, the settling test was conducted to find out the relationship between the mixing intensity and the settling ability of flocs. The hydraulic tracer-test was conducted for the various flocculation processes that have different structures of flocculation basins. In the result, the retention time distribution (RTD) curves for the flocculation processes were quite different. In case of the inappropriate structure of the flocculation basin, the flow is not even so that the floc does not grow enough. To find out the relationship between mixing intensity and settleability of flocs, G-values were calculated and the settling test was conducted for two flocculation basins which have the same conditions except the G-value. For the flocculation basin with uneven G-value, the floc settleability was revealed poor. On the other hand, the flocculation basin with even G-value, the settleability was better than the previous one. From these experimental results, it is confirmed that the flow pattern is closely related to the structure of the flocculation basin and the settleability is affected by mixing intensity. Therefore the flow pattern and the strength of the mixing intensity should be examined sufficiently to design and operate flocculation basin.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.18 no.1
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• pp.30-38
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• 2015

Purpose: The aims of our study were to evaluate the blood urea nitrogen to creatinine ratio (BUN/Cr ratio) for distinguishing between an upper and lower gastrointestinal bleeding (GIB), and differentiating between the two most common causes of upper gastrointestinal bleeding (UGIB) presenting with melena in children. Methods: Retrospective data of patients with GIB presenting with melena were analyzed. The data from 60 cases were reviewed including demographics, laboratory findings, diagnostic modalities and results, treatments, and transfusions. Results: Among the 60 cases, UGIB and lower gastrointestinal bleeding (LGIB) were found in 35 cases (58.3%) and 14 cases (23.3%), respectively. The two common causes of UGIB were varices (37.1%), and peptic ulcer diseases (PUD) (31.4%). The BUN/Cr ratio of 30 or greater was higher in UGIB than LGIB (odds ratio [OR], 6.9; 95% confidence interval [95% CI], 1.3-37.2). In UGIB, the BUN/Cr ratio of the varices group was higher than that of the PUD group (p=0.015). The OR for the BUN/Cr ratio appeared as 1.2 per unit increase in the varices group than the PUD group (95% CI, 1.03-1.3). There was no difference between the PUD group and Meckel's diverticulum group. Conclusion: The BUN/Cr ratio was not uneven in differentiating UGIB from LGIB of children with melena in our study. This suggests that BUN/Cr ratio should be interpreted carefully.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.2587-2593
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• 2014

Ceramic Injection Molding (CIM) is one of wide used processes in industry field and the applications are gradually being expanded to parts of medical and electric devices. In this study, the CIM process were analyzed with FEM and process parameters were studied and analyzed the effect on product quality. The shape of simple flat plate was compared to the shapes with the hole, with the round corner portion or with the side wall portion. If there are holes then the hole around the uneven density distribution and the defects such as weld lines could be occurred. The Large radius of the corners of the product give good formability and fluidity. Not only the shape parameters of product but also the process parameters during CIM are studied. The simulation results showed that the process parameters of temperature, initial fractions and velocity are important design parameters to improve the quality of products.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.431-437
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• 2017

In this study, based on the RPS algorithm, the application results to an electrically controlled suspension system using previewed road information are presented. Reducing the excessive vibration induced by a disturbance transmitted to the system and secure its stability is a major issue. In particular, in the automotive industry, the demand is constantly being raised. A typical external disturbance causing vibration and instability of a vehicle is an irregular roadway surface that contacts a running vehicle tire. Therefore, obtaining such profile information is an important process. The RPS algorithm using a multi sensor system was constructed and implemented in a real car. Through experimental work using the RPS system included non-contact type optical sensors, it could robustly reconstruct the road input profiles from the intermixed data onto the vehicle's dynamic motion while traveling at an uneven roadway surface. A controller with a preview control was designed in the framework of a semi-active suspension system based on the 7 degrees of freedom full vehicle model. The control performance of the system was evaluated through simulations and the results were compared with the passive vehicle condition. These results highlight the feasibility of the presented control frame.

• Journal of KIISE:Software and Applications
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• v.30 no.11
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• pp.1092-1101
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• 2003

Most of 3D character animation adjusts the gait of their characters for various terrains, using motion capture data through the motion capture equipments. This motion capture data can be naturally presented as real human motions, which are to be adjusted according to the various types of terrain. In addition, there would be a difficulty applying motion capture data for other characters in which the motion data will be captured again or edited for the existing motion data. Therefore, this paper proposes a method that is to generate walking motion for various terrains, such as flat, inclined plane, stair, and irregular face, and a method that is to calculate the trajectory of the swing leg and pelvis. These methods are able to generate various gaits controlled by the parameters of body height, walking speed, stride, etc. In addition, the positions and angles of joint can be calculated by using inverse kinematics, and the cubic spline will be used to calculate the trajectory of the joint.

• Advances in nano research
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• v.8 no.1
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• pp.83-94
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• 2020

An analytical formulation and solution process for the buckling analysis of porous magneto-electro-elastic functionally graded (MEE-FG) beam via different thermal loadings and various boundary conditions is suggested in this paper. Magneto electro mechanical coupling properties of FGM beam are taken to vary via the thickness direction of beam. The rule of power-law is changed to consider inclusion of porosity according to even and uneven distribution. Pores possibly occur inside FGMs due the result of technical problems that lead to creation of micro-voids in these materials. Change in pores along the thickness direction stimulates the mechanical and physical properties. Four-variable tangential-exponential refined theory is employed to derive the governing equations and boundary conditions of porous FGM beam under magneto-electrical field via Hamilton's principle. An analytical model procedure is adopted to achieve the non-dimensional buckling load of porous FG beam exposed to magneto-electrical field with various boundary conditions. In order to evaluate the influence of thermal loadings, material graduation exponent, coefficient of porosity, porosity distribution, magnetic potential, electric voltage and boundary conditions on the critical buckling temperature of the beam made of magneto electro elastic FG materials with porosities a parametric study is presented. It is concluded that these parameters play remarkable roles on the buckling behavior of porous MEE-FG beam. The results for simpler states are proved for exactness with known data in the literature. The proposed numerical results can serve as benchmarks for future analyses of MEE-FG beam with porosity phases.

• Structural Engineering and Mechanics
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• v.76 no.3
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• pp.279-291
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• 2020

The seismic design of conventional frame structures is meant to enhance plastic deformations at beam ends and prevent yielding in columns. To this end, columns are made stronger than beams. Yet yielding in columns cannot be avoided with the column-to-beam strength ratios (about 1.3) prescribed by seismic codes. Preventing plastic deformations in columns calls for ratios close to 4, which is not feasible for economic reasons. Furthermore, material properties and the rearrangement of geometric shapes inevitably make the distribution of damage among stories uneven. Damage in the i-th story can be characterized as the accumulated plastic strain energy (W_pi) normalized by the product of the story shear force (Q_yi) and drift (δ_yi) at yielding. Past studies showed that the distribution of the plastic strain energy dissipation demand, W_pi/ΣW_pj, can be evaluated from the deviation of Q_yi with respect to an "optimum value" that would make the ratio W_pi/(Q_yiδ_yi) -i.e. the damage- equal in all stories. This paper investigates how the soil type and ductility demand affect the optimum lateral strength distribution. New optimum lateral strength distributions are put forth and compared with others proposed in the literature.

• Korean Journal of Remote Sensing
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• v.10 no.2
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• pp.37-48
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• 1994

In spatial information processing, particularly in non-renewable resource exploration, the spatial data sets, including remote sensing, geophysical and geochemical data, have to be geocoded onto a reference map and integrated for the final analysis and interpretation. Application of a computer based GIS(Geographical Information System of Geological Information System) at some point of the spatial data integration/fusion processing is now a logical and essential step. It should, however, be pointed out that the basic concepts of the GIS based spatial data fusion were developed with insufficient mathematical understanding of spatial characteristics or quantitative modeling framwork of the data. Furthermore many remote sensing and geological data sets, available for many exploration projects, are spatially incomplete in coverage and interduce spatially uneven information distribution. In addition, spectral information of many spatial data sets is often imprecise due to digital rescaling. Direct applications of GIS systems to spatial data fusion can therefore result in seriously erroneous final results. To resolve this problem, some of the important mathematical information representation techniques are briefly reviewed and discussed in this paper with condideration of spatial and spectral characteristics of the common remote sensing and exploration data. They include the basic probabilistic approach, the evidential belief function approach (Dempster-Shafer method) and the fuzzy logic approach. Even though the basic concepts of these three approaches are different, proper application of the techniques and careful interpretation of the final results are expected to yield acceptable conclusions in cach case. Actual tests with real data (Moon, 1990a; An etal., 1991, 1992, 1993) have shown that implementation and application of the methods discussed in this paper consistently provide more accurate final results than most direct applications of GIS techniques.

• Structural Engineering and Mechanics
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• v.72 no.1
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• pp.113-129
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• 2019

A four-variable shear deformation refined plate theory has been proposed for dynamic characteristics of smart plates made of porous magneto-electro-elastic functionally graded (MEE-FG) materials with various boundary conditions by using an analytical method. Magneto-electro-elastic properties of FGM plate are supposed to vary through the thickness direction and are estimated through the modified power-law rule in which the porosities with even and uneven type are approximated. Pores possibly occur inside functionally graded materials (FGMs) due the result of technical problems that lead to creation of micro-voids in these materials. The variation of pores along the thickness direction influences the mechanical properties. The governing differential equations and boundary conditions of embedded porous FGM plate under magneto-electrical field are derived through Hamilton's principle based on a four-variable tangential-exponential refined theory which avoids the use of shear correction factors. An analytical solution procedure is used to achieve the natural frequencies of embedded porous FG plate supposed to magneto-electrical field with various boundary condition. A parametric study is led to carry out the effects of material graduation exponent, coefficient of porosity, magnetic potential, electric voltage, elastic foundation parameters, various boundary conditions and plate side-to-thickness ratio on natural frequencies of the porous MEE-FG plate. It is concluded that these parameters play significant roles on the dynamic behavior of porous MEE-FG plates. Presented numerical results can serve as benchmarks for future analyses of MEE-FG plates with porosity phases.

• Journal of Adhesion and Interface
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• v.20 no.3
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• pp.96-101
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• 2019

In this study, the flame retardant and physical properties of the expandable graphite/polyurethane foam composites were considered by the addition of expandable graphite. The tensile strength of expandable graphite/polyurethane foam composites decreased with the content of the expandable graphite and the analysis of cell shape by SEM has shown that as the expandable graphite content increases, the cell becomes uneven and collapses. As the results of the compressive strength, density and air permeability tests, it was found that density and as the content of the expandable graphite increased, the compressive strength of the composites increased but air permeability decreased. When the amount of expandable graphite was added at 10 phr or higher, the foam has excellent flame retardation performance. Analysis of the degree of diffraction by X-ray diffraction (XRD) showed that as the content of the expandable graphite increased, the crystal peak of the graphite appeared near $2{\theta}=26^{\circ}$.