• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.709-713
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• 2004

Characteristics of laser-assisted wet etching of titanium in phosphoric acid were investigated to examine the feasibility of this method for fabrication of high aspect ratio microchannels. Laser power, number of scans, etchant concentration, position of beam waist and scanning speed were taken into consideration as the major process parameters exerting the temperature distribution and the cross sectional profile of etched channels. Experimental results indicated that laser power influences on both etch width and depth while number of scans and scanning speed mainly affect on the etch depth. At a low etchant concentration, the cross sectional profile of an etched channel becomes a U-shape but it gradually turns into a V-shape as the concentration increases. On the other hand, surface of the laser beam focus with respect to the sample surface is found to be a key factor determining the bubble dynamics and thus the process stability. It is demonstrated that metallic microchannels with different cross sectional profiles can be fabricated by properly controlling the process parameters. Microchannels of aspect ratio up to 8 with the width and depth ranges of 8∼32 m and 50∼300 m, respectively, were fabricated.

• 치위생과학회지
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• 제23권4호
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• pp.389-395
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• 2023

Background: Dental caries prevention is a key research focus in dentistry, requiring advancements in the formulation of dental sealants. This study investigated the physical and antibacterial attributes of dental sealant enriched with phytoncide. Methods: Phytoncide was mixed with a commercially available dental sealant (Clinpro) at concentrations of 0 (control), 1.5%, 3%, and 4.5% by weight (wt%). The flexural strength, curing depth, and wettability of the dental sealant were measured. Antibacterial properties against Streptococcus mutans were evaluated through the enumeration of colony-forming units. Statistical analyses employed one-way variance analysis followed by Tukey's test (p<0.05). Results: The dental sealant containing 3% phytoncide showed no significant difference in flexural strength and curing depth compared with that in the control group (p>0.05). The flexural strength and curing depth decreased with increasing phytoncide content and significantly differed in sealant containing 4.5 wt% phytoncide (p<0.05). Wettability did not differ between the experimental and control groups (p>0.05). The antibacterial properties of the sealant containing 1.5% phytoncide were the same as those of the control group (p>0.05). The bacterial viability was significantly reduced in groups containing 3% and 4.5% phytoncide compared with that in the control group (p<0.05). Conclusion: Dental sealants incorporating phytoncide have a promising potential as antibacterial dental materials.

• ETRI Journal
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• 제29권3호
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• pp.353-362
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• 2007

In this paper, we propose a novel unsupervised video object extraction algorithm for individual images or image sequences with low depth of field (DOF). Low DOF is a popular photographic technique which enables the representation of the photographer's intention by giving a clear focus only on an object of interest (OOI). We first describe a fast and efficient scheme for extracting OOIs from individual low-DOF images and then extend it to deal with image sequences with low DOF in the next part. The basic algorithm unfolds into three modules. In the first module, a higher-order statistics map, which represents the spatial distribution of the high-frequency components, is obtained from an input low-DOF image. The second module locates the block-based OOI for further processing. Using the block-based OOI, the final OOI is obtained with pixel-level accuracy. We also present an algorithm to extend the extraction scheme to image sequences with low DOF. The proposed system does not require any user assistance to determine the initial OOI. This is possible due to the use of low-DOF images. The experimental results indicate that the proposed algorithm can serve as an effective tool for applications, such as 2D to 3D and photo-realistic video scene generation.

• 공학교육연구
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• 제18권1호
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• pp.54-60
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• 2015

본 논문은 자기주도학습과 심층면담 프로그램이 이공계 학습부진학생의 학업성취도에 미치는 영향을 연구한 것이다. 본 연구는 학점평균 2.5미만의 학생들 17명의 신청을 받아 진행하였으며, 15주 동안의 자기주도학습 프로그램 참여와 3차의 심층면담 결과, 평균 평점(GPA, grade point average)의 변화를 분석하였다. 그 결과 참여 과목의 학업성취도, 평균 평점(GPA, grade point average)이 높아지는 효과가 있었으며, 학습 필요성에 대한 인식이 긍정적으로 변화한 것을 확인할 수 있었다.

• 한국인터넷방송통신학회논문지
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• 제11권3호
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• pp.129-135
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• 2011

본 논문에서는 2D 동영상을 3D 입체영상으로 변환하기 위해서 머신러닝에 의한 학습기반의 객체분할과 객체의 optical flow를 활용하는 방법을 제안한다. 성공적인 3D 변환을 가능하게 하는 객체분할을 위해서, 객체의 칼라 및 텍스쳐 정보는 학습을 통해 반영하고 움직임이 있는 영역 위주로 객체분할을 수행할 수 있도록 optical flow를 도입한 새로운 에너지함수를 설계하도록 한다. 분할된 객체들에 대해 optical flow 크기에 따른 깊이맵을 추출하여 입체영상에 필요한 좌우 영상을 합성하여 생성하도록 한다. 제안한 기법으로 인해 효과적인 객체분할과 깊이맵을 생성하여 2D 동영상에서 3D 입체동영상으로 변환됨을 실험결과들이 보여준다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.255-260
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• 1993

This study proposed a new autofocusing method for a high resolution microscope with a depth of focus of a submicron range. The experimental setup was characterized by nulling method for bi-cell prhotodiode which had two active areas on sensor surface. The optical systems used in this method had was very simple and was easily matched to microscopes which had used widely. It was shown that the resolution was very high (about 20 nm) by experimental results. This method can be used in the semiconduct industry because it can find defects on the silcon wafer.

• 국제초고층학회논문집
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• 제12권1호
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• pp.75-82
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• 2023

By limiting population and land resources, a high-density urban form has become the inevitable choice for central cities in the rapid growth of many large cities in China. Due to the shift in urban growth and focus, high-density urban areas require restoration and improvement. This study intends to combine ancient and new districts, establish strategies for enhancing urban function, spatial utility, industry, and transportation, and thus enhance regional holistic effectiveness, by performing in-depth research.

• 복식문화연구
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• 제18권6호
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• pp.1242-1253
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• 2010

The purpose of this study is to suggest a designing method with excellent body suitability by analyzing clothingwearing porosity, comparing and analyzing patterns, and evaluating outer appearances by designing a prototype of study applied with design measurements for categories that have influence on the outer appearance of clothing through diverse research methods, by comparing and analyzing bunka and new bunka style basic pattern, which are proportional basic patterns most frequently used in schools for educational use to design bodice pattern for elderly women in their late 60s. As for the process of this study, the first stage selected study subjects, measured bodies. The second stage compared patterns of bunka and new bunka style basic pattern and evaluated outer appearances that deduced important pattern designing categories to design upper-torso bodice pattern of elderly women. The results of this study are as following ; As a result of comparing and analyzing bunka and new bunka style basic pattern, overall evaluation of outer appearance was excellent for new bunka style basic pattern, and bunka basic pattern received better reviews for the width and depth of front neck. In terms of waist circumference, waist front length, bust point location and bust point-bust point, bunka and new bunka style basic patterns showed a significant difference. new bunka style basic pattern had 4.5cm larger front armhole depth than bunka basic pattern, so it was evaluated to have more appropriate front armhole length, bust point location, and bust point-bust point. Through observation for primary excellent categories and precedent studies, 7 categories of front neck width, front neck depth, front interscye, back neck width, back neck depth, back interscye, and back armhole depth were deduced to have relations to the extra room around arm holes and waist that affect pattern designing method and porosity and evaluations of outer appearance.

• Journal of Welding and Joining
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• 제15권3호
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• pp.88-98
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• 1997

Welding defects, such as porosity and spike, have sometimes occurred in deep penetration electron beam welds. These defects are known to be one of the serious problem in electron beam welds. So, effects of active parameters ($a_b$) on bead shape and occurrence of defects in electron beam welds of heavy section 9%Ni steel plates were investigated. Partial penetration welding in flat position, and deep penetration welding of 10 ~ 28mm depth were investigated in this study. It is desirable to select low accelerating voltage and above the surface focus position $a_b$$\geq$1.2 at which a wine-cup shaped bead is obtained to avoid the welding defects such as spike and root porosity. When the accelerating voltage of electron beam was low (90kV), active parameter ($a_b$) did not influence on the bead width, penetration depth and weld defects significantly. However, in case of high voltage ($\geq$120kV), active parameter ($a_b$) was sensitively associated with penetraton depth and weld defects, i.e. when the active parameter (($a_b$) was in the range of 0.6 to 1.0, the depth of penetration was always over the target (23mm), while the depth of penetration was dramatically decreased with further increase of active parameter ($a_b$). The weld defects were decreased with the increase of active parameter $a_b$ resulting in the decrease of energy density of the focused beam in the root part of fusion zone.

• 한국컴퓨터정보학회논문지
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• 제28권10호
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• pp.85-92
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• 2023

본 논문에서는 장편의 드라마나 영화에서 스토리 기반의 축약된 요약본을 자동으로 제작하기 위한 방법을 제안한다. 촬영 단계에서 황금분할을 고려한 공간감 있는 프레임 구성과 내용 전달 차원에서 시청자들의 시선을 집중시키기 위한 관심 대상에 대한 초점을 기본 전제로 했다. 이에 적정한 프레임들을 추출하기 위한 방법을 고려하기 위해서 기존의 씬(scene) 및 숏(shot) 검출에 대한 연구, 초점과 관련된 블러 정도를 파악하는 연구들에서 활용되었던 요소 기술들을 활용했다. 유튜브에서 공유되는 영상을 프레임 단위로 변환한 후 프레임별로 특징을 추출하기 위한 영역으로 프레임 전체 영역과 3개의 부분 영역으로 구분했고, 해당 영역별로 각각 라플라시안 연산자와 FFT를 적용한 결과들을 비교하여 상대적으로 일관성 있고 강건한 FFT를 선택했다. 프레임 전체에 대한 계산값과 3개 영역의 계산값들을 비교하여 상대적으로 선명한 영역을 확인할 수 있는 조건을 기반으로 대상 프레임을 선별했다. 이렇게 선별된 결과를 토대로 숏 내에서 프레임들의 연속성을 확보하기 위해 오프라인 변화점 탐지기법을 적용한 결과와 접목시켜 최종 프레임들을 추출했고, 이를 기반으로 편집결정리스트를 구성하였으며, F1-스코어 75.9%를 갖는 62.77%로 축약된 요약본을 제작했다.