• Restorative Dentistry and Endodontics
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• 제45권2호
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• pp.11.1-11.9
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• 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.

• 정보교육학회논문지
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• 제25권3호
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• pp.557-569
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• 2021

미래 사회를 위한 대비로 교육과정은 시대의 흐름에 맞게 변화하고 있으며 4차 산업혁명 시대가 도래하면서 새로운 2015 개정 교육과정의 목적이 창의적인 융합인재를 육성하는 것으로 제시되었다. 소프트웨어 교육의 목적은 창의성 증진이며 나아가 실생활과 연계하여 문제해결력을 기르도록 하는 것이다. 또한, 학습에 대한 몰입도는 뛰어난 교육 성취로 이어진다. 그러나 여전히 초등학교 컴퓨터 교육에서는 학생들이 쉽게 몰입하고 창의적인 문제해결력을 증진하기 위한 융합수업 모델의 개발이 부족한 실정이다. 이에 본 연구에서는 이러한 교육 여건에 맞는 융합수업 모델인 노벨엔지니어링(novel engineering)을 활용한 컴퓨터 융합교육을 설계하고, 이를 수업에 적용하였다. 그리고 학습 몰입도와 창의적 문제해결력 증진에 미치는 영향을 측정하기 위하여 초등학교 6학년을 대상으로 노벨엔지니어링 기반 컴퓨터 수업을 실험 집단에 적용하였고, 일반적인 컴퓨터 수업을 통제 집단에 적용하였다. 집단 간 사전-사후 검사 결과 노벨엔지니어링을 활용한 컴퓨터 수업은 학습몰입도와 창의적 문제해결력 신장에 긍정적인 영향을 미치는 것으로 밝혀졌다.

• International Journal of Vascular Biomedical Engineering
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• 제1권2호
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• pp.30-35
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• 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
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• 한국가시화정보학회 2007년도 추계학술대회
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• pp.143-148
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• 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
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• 제40권3호
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• pp.277-283
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• 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.

• 한국산학기술학회논문지
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• 제22권6호
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• pp.299-304
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• 2021

본 연구의 목적은 보육교사의 공감능력, 교수몰입, 행복감에 미치는 영향을 분석하는데 있다. 연구대상은 U시 보육교사 111명을 대상으로 실시하였다. 분석방법은 SPSS 22.0 프로그램을 사용하여 빈도분석, 신뢰도분석, 상관관계분석을 실시하였으며, 변수 간의 인과관계에 대한 회귀분석을 실시하였다. 연구결과 첫째, 보육교사의 공감능력이 행복감에 미치는 하위요인인 인지적 공감 요인은 행복감에 긍정적으로 유의미한 영향을 미치는 것으로 나타났다. 반면, 교사의 공감능력의 하위요인인 정서적 공감 요인은 행복감에 유의미한 영향을 미치지 않는 것으로 나타났다. 둘째, 보육교사의 교수몰입이 행복감에 미치는 영향을 살펴본 결과 교수몰입 요인은 행복감에 긍정적으로 유의미한 영향을 미치는 것으로 나타났다. 이는 보육교사의 공감능력 하위요인인 인지적 공감 요인이 높을수록 행복감이 높아지며, 교수몰입 요인이 높을수록 행복감이 높아진다는 것을 의미하는 것이다. 본 연구의 시사점은 보육교사의 공감능력, 교수몰입, 행복감과의 관계를 파악함으로써 보육교사들의 행복감 향상을 위한 방안 마련의 기초자료가 될 것으로 사료된다.

• 한국도로학회논문집
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• 제15권2호
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• pp.73-81
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• 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.

• 한국가시화정보학회지
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• 제10권2호
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• pp.20-24
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• 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.

• 상하수도학회지
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• 제19권6호
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• pp.819-826
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• 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
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• 제10권1호
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• pp.56-63
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• 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.