• Smart Structures and Systems
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• 제26권5호
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• pp.657-666
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• 2020

A rotational pulse-echo ultrasonic propagation imager that can inspect cylindrical specimens for material nondestructive evaluations is proposed herein. In this system, a laser-generated ultrasonic bulk wave is used for inspection, which enables a clear visualization of subsurface defects with a precise reproduction of the damage shape and size. The ultrasonic waves are generated by a Q-switched laser that impinges on the outer surface of the specimen walls. The generated waves travel through the walls and their echo is detected by a Laser Doppler Vibrometer (LDV) at the same point. To obtain the optimal Signal-to-Noise Ratio (SNR) of the measured signal, the LDV requires the sensed surface to be at a right angle to the laser beam and at a predefined constant standoff distance from the laser head. For flat specimens, these constraints can be easily satisfied by performing a raster scan using a dual-axis linear stage. However, this arrangement cannot be used for cylindrical specimens owing to their curved nature. To inspect the cylindrical specimens, a circular scan technology is newly proposed for pulse-echo laser ultrasound. A rotational stage is coupled with a single-axis linear stage to inspect the desired area of the specimen. This system arrangement ensures that the standoff distance and beam incidence angle are maintained while the cylindrical specimen is being inspected. This enables the inspection of a curved specimen while maintaining the optimal SNR. The measurement result is displayed in parallel with the on-going inspection. The inspection data used in scanning are mapped from rotational coordinates to linear coordinates for visualization and post-processing of results. A graphical user interface software is implemented in C++ using a QT framework and controls all the individual blocks of the system and implements the necessary image processing, scan calculations, data acquisition, signal processing and result visualization.

• 한국과학교육학회지
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• 제35권2호
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• pp.231-245
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• 2015

과학 교육에서도 플립 러닝은 혁신적인 교수 방법으로 사용될 수 있다. 본 연구에서는 초등 예비교사들이 플립 러닝을 위해 제작한 동영상을 분석하고, 효과적인 시각화 구성 전략을 탐색하였다. 초등 예비교사들은 지구 영역의 과학수업을 위해 구체적 사례 선택하기 전략을 사용하여 거시적인 자연현상에 대한 정보를 제공하는 데 중점을 두고 있었다. 구체적 사례를 전달하기 위해 마커와 공간변환 요소를 효과적으로 사용하였으나, 학생들의 경험과 관련지으려는 노력이 부족하였다. 또한 학생들의 심상을 강화하기 위해 간단하게 도식화하거나 극단적인 사례를 제시하는 경우는 매우 드물었다. 마지막으로 효과적인 시각화 자료를 구성하기 위해서는 다중 표상의 구체적 사례를 제시하고, 친숙한 사례나 비유 모델을 통하여 학생들의 경험과 긴밀히 연결지어 주어야 한다. 또 심상을 강화하기 위해 간단하게 도식화하기, 극단적 사례를 제시하여 새로운 상황 추리할 수 있는 기회를 부여해야 한다.

• 한국가시화정보학회지
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• 제14권1호
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• pp.40-45
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• 2016

Elimination of the smear layer and bacteria in the root canal is the most important in the endodontic treatment, and various irrigation devices have been developed. Nevertheless, it is hard to eliminate the smear layer and bacteria completely. In this paper, a micro bubble irrigation system has been developed for the root canal cleaning of tooth. Micro bubbles are generated when pressurized fluids passing through a porous material inside a hand-piece nozzle, and the bubbly flows excited by ultrasonic vibration are observed using a high-speed camera and a microscope. The results show that the diameter and number of bubbles increases with the applied pressure, and there found an optimum excitation frequency in order to minimize the bubble size. From in-vitro tests, it is also verified that the developed bubble irrigation system has the ability of antibacterial and infection removal. Thus, this biocompatible system would be well suited for root canal cleaning.

• 한국안전학회지
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• 제27권6호
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• pp.93-98
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• 2012

In order to capture the fast crack propagation in an unmanipulated concrete fracture test, we employed mechanoluminascent(ML) material, which emits visible light when stressed, as a crack visualization tool. Three-point bending fracture test setup, a paint type ML material and a high speed camera were used to capture the images of fast moving cracks. The maximum size of coarse aggregates of concrete was used as an experimental parameter. The crack images, loading, and crack mouth opening displacement were successfully recorded as a function of time elapsed. From the test results, several interesting cracking behavior in the unmanipulated fracture test was observed in such that (1) the crack moves fast while the load is slowly decreased after the maximum loading, and (2) the crack in concrete with larger coarse aggregates moves faster than the others.

• 한국CDE학회논문집
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• 제21권3호
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• pp.224-233
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• 2016

We propose a new method to visualize 3D models for FDM (Fused Deposition. Modeling) printing that appearance of the printed results can be predicted more realistically as that the efficiency of the modeling-printing process can be improved. The layered nature of horizontal slicing and the vibratory nozzle movements of customer-level FDM 3D printers leaving the characteristic patterns of noisy stripes on the surfaces of printed objects make difficulties in prediction of printed result in company with the thermal contraction of filament material. First, our method analyses the G-codes generated by common slicers to obtain proper outlines and take advantages of a modified version of Perlin noise based texturing method for rendering efficiency and enough number of control parameters on the visual details. The results show improved rendering details of pre-visualization of FDM printing.

• Ocean Systems Engineering
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• 제9권1호
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• pp.79-95
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• 2019

The material analysis of an offshore structure is generally conducted in the contract design phase for the price quotation of a new offshore project. This analysis is conducted manually by an engineer, which is time-consuming and can lead to inaccurate results, because the data size from previous projects is too large, and there are so many materials to consider. In this study, the piping materials in an offshore structure are analyzed for contract design using a big data framework. The big data technologies used include HDFS (Hadoop Distributed File System) for data saving, Hive and HBase for the database to handle the saved data, Spark and Kylin for data processing, and Zeppelin for user interface and visualization. The analyzed results show that the proposed big data framework can reduce the efforts put toward contract design in the estimation of the piping material cost.

• 한국문헌정보학회지
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• 제58권2호
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• pp.225-249
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• 2024

본 연구의 목적은 지도 기반 데이터 시각화 플랫폼에 적합한 평가 도구를 개발하고, 이를 현재 상용되고 있는 지역간 정보를 나타내는 지도 기반 데이터 시각화 플랫폼을 대상으로 휴리스틱 사용성 평가를 수행하는 것이다. 본 연구에서는 Nielsen(1994)의 사용성 평가 10가지 원칙과 함께 지도 기반 플랫폼의 사용성 평가 기준을 다룬 선행연구들의 결과를 비교·분석하여 (1) 가시성, (2) 실세계와의 일치, (3) 일관성 및 표준, (4) 사용자 제어 여부와 친화성, (5) 융통성, (6) 디자인, (7) 호환성, (8) 오류 방지 및 해결, (9) 도움말 제공 및 문서화로 9가지의 평가 항목을 개발하였다. 또한, 개발한 평가 항목의 실효성을 확인하기 위해, 국내외 5개의 지도 기반 데이터 시각화 플랫폼을 대상으로 전문가 4명을 초빙하여 사용성 평가를 진행하였다. 평가 결과, 전문가들은 제안한 지도 기반 데이터 시각화 사용성 평가 기준을 사용하여, 수치화한 점수와 주관적 의견을 포함한 5개 플랫폼의 사용성을 순위화한 평가 결과를 도출할 수 있었다. 본 연구의 결과는 향후 지도 기반 시각화 플랫폼을 개발하고 평가함에 있어서 전반적인 가이드라인의 기초 자료가 될 수 있을 것으로 기대한다.

• 한국가시화정보학회지
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• 제8권3호
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• pp.22-28
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• 2010

In the present study, we performed the velocity field measurement in a microchannel using a focal length variable micro liquid lens. The liquid lens is used as a beam expander in a micro-PIV system to acquire the scatter image of the seeded particle. A thin film-type micro liquid lens was made of PDMS material and it was attached on top of the 700-micron-wide working fluid supply channel trench. As a result, the focal length and contact angle of the liquid lens changed with variations in applied pressure.

• 한국가시화정보학회지
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• 제5권1호
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• pp.12-15
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• 2007

Macromolecule diffusion in cells and tissues is important for cell signaling, metabolism and locomotion. Biophysical methods, including non-invasive or minimally invasive in-vivo photobleaching techniques and single quantum-dot tracking, have been used to measure the rates of macromolecule diffusion in living cells and tissues, including central nervous system and tumors. Mathematical modeling and statistical analysis of experimental data revealed various modes of diffusion, which are strongly coupled with spatiotemporal changes in nanoscale structures and material properties.

• East Asian mathematical journal
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• 제36권4호
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• pp.455-474
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• 2020

In this study, we investigate the latus rectum, one of the geometric measures of the conics, as one of the ways in which learners harmonize the geometric and algebraic approaches to conics from a pedagogical point of view. We also introduce the conical curve of Biot as presented in 'The Discourse on the Latus Rectum in conics(2013)' by Takeshi Sugimoto and reinterpret it for visualization and use as teaching material. Therefore, we expect that the importance of mathematical concepts will be recognized in conics and students can experience geometry learning that is explored in the school field and have a positive effect in developing the power to apply even in the context of applied problems.