• Restorative Dentistry and Endodontics
• /
• v.45 no.2
• /
• pp.11.1-11.9
• /
• 2020

Objectives: This study compared the flow and filling of several retrograde filling materials using new different test models. Materials and Methods: Glass plates were manufactured with a central cavity and 4 grooves in the horizontal and vertical directions. Grooves with the dimensions used in the previous study (1 × 1 × 2 mm; length, width, and height respectively) were compared with grooves measuring 1 × 1 × 1 and 1 × 2 × 1 mm. Biodentine, intermediate restorative material (IRM), and mineral trioxide aggregate (MTA) were evaluated. Each material was placed in the central cavity, and then another glass plate and a metal weight were placed over the cement. The glass plate/material set was scanned using micro-computed tomography. Flow was calculated by linear measurements in the grooves. Central filling was calculated in the central cavity (㎣) and lateral filling was measured up to 2 mm from the central cavity. Results: Biodentine presented the least flow and better filling than IRM when evaluated in the 1 × 1 × 2 model. In a comparison of the test models, MTA had the most flow in the 1 × 1 × 2 model. All materials had lower lateral filling when the 1 × 1 × 2 model was used. Conclusions: Flow and filling were affected by the size of the test models. Higher grooves and materials with greater flow resulted in lower filling capacity. The test model measuring 1 × 1 × 2 mm showed a better ability to differentiate among the materials.

• Journal of The Korean Association of Information Education
• /
• v.25 no.3
• /
• pp.557-569
• /
• 2021

In preparation for the future society, the educational curriculum is changing according to the trend of the times, and with the advent of the era of the 4th Industrial Revolution, the purpose of the new 2015 revised curriculum was suggested to foster the convergence creativity of students. The purpose of software education is to promote creativity and further develop problem-solving skills in connection with real life. In addition, flow in learning leads to outstanding educational achievement. However, in elementary school computer education, there is still a lack of development of a convergence class model for students to easily immerse themselves and promote creative problem-solving skills. Therefore, in this study, we designed convergence computer education using Novel Engineering, which is a convergence class model suitable for these educational conditions and applied it to classes. Further, to measure the effect on the improvement of learning flow and creative problem-solving ability. the Novel Engineering-based computer class was applied to the experimental group for 6th graders, and the general computer class was applied to the control group. As a result of the pre-post test between groups, it was found that computer classes using Novel Engineering had a positive effect on learning flow and creative problem-solving ability.

• International Journal of Vascular Biomedical Engineering
• /
• v.1 no.2
• /
• pp.30-35
• /
• 2003

Flow characteristics of blood flow in a micro channel were investigated experimentally using a micro-PIV (Particle Image Velocimetry) velocity field measurement technique. The main objective of this study was to understand the real blood flow in micron-sized blood vessels. The Reynolds number based on the hydraulic diameter of micro-channel for deionized (DI) water was about Re=0.34. For each experimental condition, 100 instantaneous velocity fields were captured and ensemble-averaged to get the spatial distributions of mean velocity. In addition, the motion of RBC (Red Blood Cell) was visualized with a high-speed CCD camera. The captured flow images of nano-scale fluorescent tracer particles in DI water were clear and gave good velocity tracking-ability. However, there were substantial velocity variations in the central region of real blood flow in a micro-channel due to the presence of red blood cells.

• 한국가시화정보학회:학술대회논문집
• /
• 2007.11a
• /
• pp.143-148
• /
• 2007

In comparison with previous researches for swirling flow, the spiral flow self-generated in the spiral flow nozzle has some different characteristics. It is not needed a compulsive tangential momentum to get its velocity component and has long potential core, relatively low swirl ratio, and high focusing ability. In this study, the self-generated mechanism of the spiral flow was clarified and the effect on the width of annular slit on spiral flow characteristics was investigated experimentally and numerically. As a result, the existence of tangential velocity component regardless of a compulsive angular momentum is clarified and the results obtained by experiment have a satisfactory agreement with those by numerical method, quantitatively and qualitatively.

• Journal of Biosystems Engineering
• /
• v.40 no.3
• /
• pp.277-283
• /
• 2015

Background: Foodborne disease outbreaks from various food sources are a major health concern worldwide. Current methods for detection of foodborne pathogens are both expensive and time-consuming. Purpose: This review aims to present the current information available on the use of lateral flow test strips to detect pathogens in food products to enhance food safety. Results: Frequent foodborne disease outbreaks from various food sources have increased the need for rapid and easy methods for routine analysis of foodborne pathogens. Present detection methods for foodborne pathogens require expensive instruments, experts, and long time for sample analysis. Lateral flow test strips have drawn attention in recent years because of their ability to detect analytes quickly and easily. This review focuses on the principle of the lateral flow test, the various formats of lateral flow test strips, recognition elements, labeling tags, and reading instruments. In addition, this review also discusses the future prospects for the lateral flow test strips.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.6
• /
• pp.299-304
• /
• 2021

This study examined the effects of childcare teachers' empathy, teaching commitment, and feelings of happiness. The subjects were 111 childcare teachers in U city. The frequency, reliability, and correlation analysis were performed using the SPSS 22.0 program, and regression analysis was performed on the causal relationship between the variables. First, the childcare teacher's cognitive empathy factor had a positive effect on the sense of happiness. On the other hand, the emotional empathy factor, a sub-factor of the empathy ability, did not affect the feeling of happiness. Second, the childcare teacher's teaching commitment had a significant positive effect on happiness. This means that a higher cognitive empathy factor, a sub-factor of the childcare teacher's empathy ability, resulted in a higher sense of happiness. Moreover, a higher instructional commitment factor indicated a higher sense of happiness. This study provides basic data for preparing measures to improve the sense of happiness of childcare teachers by grasping the relationship between childcare teachers' empathy ability, teaching commitment, and feelings of happiness.

• International Journal of Highway Engineering
• /
• v.15 no.2
• /
• pp.73-81
• /
• 2013

PURPOSES : In this study, various laboratory tests were performed to investigate basic physical properties of the asphalt concrete which uses wasted vinyl aggregates. METHODS : The thermal conductivity, ultrasonic velocity, Marshall stability, flow, indirect tensile strength were measured according to binder content and wasted vinyl aggregate content. An experimental construction was performed to verify construct ability of the asphalt pavement using the wasted vinyl aggregates. RESULTS : The thermal conductivity and ultrasonic velocity decreased showing insulation effect by mixing more wasted vinyl aggregate, whereas stability and flow increased. The void ratio shows similar value regardless of the mixing ratio. The highest indirect tensile strength was measured at 2.5% of wasted vinyl aggregate content. The construct ability was verified by observing the process of mixing, placing, and compaction and the state of the pavement surface. CONCLUSIONS : The basic properties and construct ability of the asphalt concrete using the wasted vinyl aggregates were verified. The temperature according to pavement depth will be measured to verify the insulation effect of the wasted vinyl aggregates. In addition, amount of snowfall, snowmelt area, and ice adhesion strength will be analyzed quantitively.

• Journal of the Korean Society of Visualization
• /
• v.10 no.2
• /
• pp.20-24
• /
• 2012

Increasing the active catalyst surface area is important in improving a converter's efficiency. In addition, uniform flow is advantageous in that it produces more efficient catalytic conversion. This results in the ability to use a smaller catalytic converter with uniform flow as opposed to a larger converter requirement for non-uniform flow. Therefore, it is important to characterize the internal flow of the catalytic converter. To characterize the system's flow patterns, velocity measurements were taken at the mid and exit planes of a ceramic honeycomb catalytic converter at flow rates of 37.8 l/s and 94.4 l/s. Measurements were conducted using LDV. The profiles were measured along both the major and minor axis of the planes. Primary flow direction velocities measured along the minor axis, at both flow rates, varied greatly at the mid plane and somewhat at the exit plane. The areas of greatest air flow were seen near the edges of the walls and on the side of the converter opposite the flow's entrance region. It also appears that the high velocities opposite the intake are due to the design of the entrance region. The entrance region is possibly too small to properly redirect the vertically entering fluid into an evenly distributed flow in the primary flow direction.

• Journal of Korean Society of Water and Wastewater
• /
• v.19 no.6
• /
• pp.819-826
• /
• 2005

To guarantee the disinfection ability in clearwell, a value of CT is considered where C[mg/l] is disinfectant residual at the exit of clearwell and T[min] means $T_{10}$, the contact time when 10% of tracer is out of clearwell after introducing the tracer at the inlet. To meet a CT value required, increasing the C value is not recommended because high C value can increase potential of producing disinfection by product like THMs. Increasing the hydraulic efficiency surrogated by $T_{10}$ is thus an option widely recommended. Right now, it is widely adopted estimating $T_{10}$ considering LW ratio only due to the suggestions of previous researches. The authors think however there are other factors to consider including shape, flow rate, configuration of inlet and outlet, and the existence of intra basin. This study is initiated to closely look at the effects of two factor on hydraulic efficiency. The factors are shape and inlet flow velocity, i.e., inflow. For that, computational fluid dynamics (CFD) model is developed and pilot test is also carried out. The results show that at a L/W ratio, disinfection ability is overestimated with larger length in shape and higher inlet flow velocity. This suggests that in determining $T_{10}$, the shapes of clearwell and inlet flow velocity should also be considered as well as L/W ratio.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.1
• /
• pp.56-63
• /
• 2015

The optimization is an important role in wide geographical distribution of electrical power market, finding the optimum solution for the operation and design of power systems has become a necessity with the increasing cost of raw materials, depleting energy resources and the ever growing demand for electrical energy. In this paper, the real coded biogeography based optimization is proposed to minimize the operating cost with optimal setting of equality and inequality constraints of thermal power system. The proposed technique aims to improve the real coded searing ability, unravel the prematurity of solution and enhance the population assortment of the biogeography based optimization algorithm by using adaptive Gaussian mutation. This algorithm is demonstrated on the standard IEEE-30 bus system and the comparative results are made with existing population based methods.