• Journal of the Korean Geotechnical Society
• /
• v.16 no.1
• /
• pp.167-178
• /
• 2000

An experimental study on step up filling method is carried out to reinforce the Yano method which is widely used to estimate volume ratio and self-weight consolidation settlement in reclamation area. This method considers actual reclamation construction in which dredged clay is continuously filled and rising of deposit height is presented as a result of volume decrease by height rising and self-weight consolidation. It measured the relationship between filling velocity and deposit rising velocity; calculated the total filling height which is needed to achieve the planned final deposit height, and its solid height and the time which is taken to finish the planned final deposit height; and on the basis of these calculated parameters, predicted the self-weight consolidation and volume change ratio in reclamation construction. Yano method is also used to predict the same conditions. 29.8% in self-weight consolidation, 31.1% in volume ratio, 40% in void ratio and water content is underestimated in Yano method compared to step up filling method.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.42 no.5
• /
• pp.87-96
• /
• 2005

In this paper, a mesh simplification algorithm using face constriction is proposed which considers the conservation of the volume of a 3D model. The face constriction method replaces three vertices of the candidate triangle with a new vertex, removing four faces at once. We propose a modified method, compensating an existing method, of considering curvature in the decision of the removing order of triangles. We also propose a method of determining a new vertex replacing the candidate triangle, which reflects curvature difference of the three surrounding areas of the three vertices of the triangle, while conserving the volume. It is shown by simulation that the proposed method conserves the volume and shows good constriction performance comparable to the other methods.

• Composites Research
• /
• v.31 no.5
• /
• pp.251-259
• /
• 2018

In this paper, statistical volume element modeling method was developed for multi-scale progressive failure analysis of fiber reinforced composite materials. Big-size statistical volume elements (BSVEs) was considered to minimize the size effect in the micro-scale, by including as many fibers as possible. For that purpose, a mesh cutting method is suggested and adapted into the fiber model generator that creates finite element domain rapidly. The fiber defect model was also developed based on the experimental distribution of the fiber strength. The size effects from the local load sharing (LLS) are evaluated by increasing the fiber inclusion in the micro-scale model. Finally, continuum damage mechanics (CDM) model to the fiber direction was extracted from numerical analysis on BSVEs. And it was compared with strength prediction from typical representative volume element (RVE) model.

• Journal of Advanced Marine Engineering and Technology
• /
• v.34 no.2
• /
• pp.250-258
• /
• 2010

A numerical analysis of reactive flow in a liftoff flame is accomplished to elucidate the characteristics of flame propagation velocity and volume integral of reaction rate with the variation of nozzle diameter and fuel injection flow rate in a liftoff flame consisted with fuel rich region, fuel lean region and diffusion flame region. The increase of fuel injection velocity enhances flame propagation velocity for the selected three nozzle diameter(d=0.25, 0.30, 0.35mm), but its effect on the flame propagation velocity is not much greater than 4.3%. The increase of fuel flow rate is directly and linearly related with the volume reaction rate and so the volume reaction rate, not the flame propagation velocity, might be considered to accommodate the variation of fuel flow rate in a liftoff flame.

• Journal of dental hygiene science
• /
• v.14 no.1
• /
• pp.15-21
• /
• 2014

The purpose of this study in vitro investigation was to evaluate the dimensional stability of dental digital models made by impression scanning method. Twenty working models were produced. Twenty impressions were made from study models. The dimensional stability of models of two groups (stone and digital models) was examined using six landmark distances. Stone models were measured through digital vernier calipers. Digital models were measured by the computer program. Statistical analyses were performed with Wilcoxon rank sum test (${\alpha}=0.05$). The mean of six landmark distances were significantly larger in the stone models than in the digital models (p<0.05) but digital models showed clinically acceptable accuracy.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.17 no.3
• /
• pp.151-155
• /
• 1997

In this research, nondestructive test using a radioisotope, $^{241}Am$ gamma-ray, was accomplished in order to evaluate the fiber volume fraction of the accumulated composite layers such as glass fiber/epoxy and carbon fiber/epoxy. Attenuation coefficients of the fiber and resin were measured respectively by NaI(T1) detector The fibers volume fraction was measured for various thickness of composite layers between 2 and 20mm. Fiber volume fraction of the composite layers were also measured for various amount of fibers. The experimental errors from nondestructive test using gamma-ray were in the range of ${\pm}1{\sim}2.5%$ in comparison with those from observation by optical microscopy. By selecting the optimum energy and activity of radioisotope, this method can provide a new means for the evaluation of the fiber volume fraction.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.8
• /
• pp.957-964
• /
• 2011

This investigation presents a finite element method to obtain the transmission properties of bulk elastic waves in piezoelectric band gap structures(phonon crystals) for varying frequencies and modes. To this end, periodic boundary conditions are imposed on a three-dimensional model while both in-plane and out-of-plane modes are included. In particular, the mode decoupling characteristics between in-plane and out-of-plane modes are identified for each electric poling direction and the results are incorporated in the finite element modeling. Through numerical simulations, the proposed modeling method was found to be a useful, effective one for analyzing the wave characteristics of various types of piezoelectric phononic band gap structures.

• Journal of Korean Society for Geospatial Information Science
• /
• v.20 no.3
• /
• pp.3-10
• /
• 2012

The investigation of valley networks and their volume provide important information about past water activities on Mars. As an alternative of conventional image processing methods, terrain filtering algorithm using pointcloud data is suggested in this study. First, the topography of pointcloud is inverted so that the valleys become positive features and the algorithm is then applied to distinguish the valleys from the surface. Ground DEM and object DEM are generated from both the valleys and the surface pointcloud then the volume of valleys is estimated by multiplying the height difference between the surface with valleys and the area of valleys based on grid cellsize. In the test of valleys adjacent to Tuscaloosa crater, the total volume of valleys was estimated to be $1.41{\times}10^{11}m^3$ with the difference of 12% and 16% compared with the infill volume of Tuscaloosa crater and BTH result respectively.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.30 no.1
• /
• pp.23-27
• /
• 2014

Purpose: The purpose of this study was to determine the dimensional stability of three rubber impression materials (polysulfide, polyvinylsiloxane, polyether) in an iodophor disinfectant. Materials and Methods: Seventy-two impressions were made with each material and divided into control, 10-minute, and 30-minute immersion groups using an iodophor as the disinfectant. A microscope was used to measure dimensional changes in the stone casts made from each group of impressions, and the percent change was analyzed using a two-way ANOVA (P = 0.05). Results: All dimensional changes after iodophor disinfection were small in 10 minute groups, however, showed significantly increased in 30 minute groups (P < 0.05). Conclusion: Clinically, it can be recommended to use iodophor disinfectant for rubber materials within 10 minute.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.10
• /
• pp.6187-6192
• /
• 2014

The use of WBRT(whole brain radiation therapy) has increased due to the increase in the incidence of metastatic brain tumors. The development of radiation therapy techniques is expected to improve the quality of life. The VMAT (Volumetric Modulated Arc Therapy) is an excellent treatment technique that can distinguish the dose in each volume. Therefore, this study compared conventional WBRT and VMAT for hair loss according to the scalp dose using a head phantom. The CI (Conformity Index), HI (Homogeneity Index) and QOC (Quality of Coverage) were measured brain tissue. A 20 percent and 50 percent dose was measured at the scalp, eyeball, lens, and c-spine. Conventional WBRT is excellent at 10 percent of brain tissue. VMAT is far superior at 1000 percent at the other organs. VMAT at the prescribed dose can be used as radiation therapy of metastatic brain tumors with less hair loss.