• Restorative Dentistry and Endodontics
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• 제24권2호
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• pp.310-321
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• 1999

In this in vitro study, confocal laser scanning microscopic morphology of dentin-resin interface and its relationship to shear bond strength were investigated after the exposed dentin surfaces were treated with 3 different kinds of dentin adhesive systems[three-step; Scotchbond Multi-Purpose Plus(SMPP), self-priming bonding resin; Single Bond(SB), self-etching primer; Clearfil Liner Bond 2(LB2)]. 52 extracted human molar teeth without caries and/or restorations. The experimental teeth were randomly divided into three groups of seventeen teeth each. In five teeth of each group, class V cavities(depth: 1.5mm) with 900 cavosurface angles were prepared at the cementoenamel junction on buccal and lingual surfaces. Bonding resins of each dentin adhesive system were mixed with rhodamine B. Primer of SMPP was mixed with fluorescein. In group 1. the exposed dentin was conditioned with etchant, applied with above primer and bonding resin of SMPP. In group 2, with etchant and self-priming bonding agent of SB. In group 3, with self-etching primer and bonding agent of LB2. After treatment with dentin adhesive systems, composite resin were applied and photocured. The experimental teeth were cut longitudinally through the center line of restoration and grounded so that about $90{\mu}m$-thick wafers of buccolingually orientated dentin were obtained. And, $70{\sim}80{\mu}m$-thick wafers sectioned horizontally, thus presenting a dentinal tubules at 900 to the cut surface of a remaining tooth, were obtained. Primer of SMPP mixed with rhodamine B was applied to these wafers. Confocal laser scanning microscopic investigations of these wafers were done within of 24 hours after treatment. To measure shear bond strength, the remaining twelve teeth of each group were grounded horizontally below the dentinoenamel junction, so that no enamel remained. After applying dentin adhesive systems on the dentin surface, composite was applied in the shape of cylinder. The cylinder was 5mm in diameter, and 2mm in thickness. Shear bond strength was measured using Instron with a cross-head speed of 0.5mm/min. It was concluded as follows ; 1. Hybrid layer of SMPP(mean: $4.56{\mu}m$) was thicker than that of any other groups. This value was not statistically significant thicker than that of SB(mean: $3.41{\mu}m$, p>0.05), and significant thicker than that of LB2(mean: $1.56{\mu}m$, p<0.05). There was a statistical difference between SB and LB2(p<0.05). 2. Although there were variations in the length of resin tag even in a sample, and in a group, most samples in SMPP and SB showed resin tags extending above $20{\mu}m$. But samples in LB2 showed resin tags of $10{\mu}m$ at best. 3. Besides primer's infiltration into demineralized peritubular dentin and dentinal tubules, fluorophore of primer was detected in the lateral branches of dentinal tubules. 4. All groups demonstrated statistically significant differences from one another(p<0.05), with shear bond strengths given in descending order as follows: SMPP(18.3MPa), SB(16.0MPa) and LB2(12.4MPa). 5. LB2 having thinnest hybrid layer($1.56{\mu}m$) showed the lowest shear bond strength(12.4MPa).

• 한국측량학회지
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• 제29권4호
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• pp.359-365
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• 2011

본 연구는 스캔라인 기반의 2차원 이웃 관계를 활용하여 레이블링 알고리즘과 윈도우 기반의 알고리즘을 함께 적용함으로써 항공레이저측량 자료의 지면점과 비지면점을 효과적으로 분리하는 것을 목적으로 한다. 이를 위하여 스캔라인 구조를 바탕으로 최소의 탐색을 통해 점들의 인접 관계를 구축하고, 구축된 인접관계를 기반으로 연결성분 레이블링 알고리즘을 적용하여 항공레이저측량 자료를 지면점과 비지면점으로 분리하였다. 그리고, 모폴로지 필터링을 통해 작은 개체를 추가로 제거하고 거리반비례 추정을 통해 고립 지면점을 복원하여 정확도를 향상시켰다. 다양한 특성을 나타내는 지역에 적용하고 평가한 결과 대부분의 점들이 올바르게 분리 되었고 약97%의 전체 정확도를 도출하였으며, 인접관계 구축 및 데이터 처리 시간이 TIN 또는 격자 구조 자료 구축시간에 비하여 적게 소요되었다.

• Journal of Microbiology and Biotechnology
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• 제10권6호
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• pp.844-850
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• 2000

The specific binding and internalization of viral particles is an essential step for the successful infection of viral pathogens. In the case of the hepatitis B virus (HBV), virions bind to the host cell via the preS domain of the viral surface antigen and are subsequently internalized by endocytosis. HBV-preS specific receptors are primarily expressed on hepatocytes, however, viral DNA and proteins have also been detected in extrahepatic sites, suggsting that celluar recepators for HBV may also exist on extrahepatic cells. Recently, an EBV-transformed B-cell line was identified onto which the preS region binds in a receptor-ligand specific manner. In this study, this specific interaction was further characterized, and the binding region within the preS protein was locaized. Also the internalization after host cell attachment was visualized and analyzed by fluorescence-labeled HBV-preS1 proteins using confocal microscopy. Energy depletion by sodium azide treatment effectively inhibited the internalization of the membrane-bound preS1 ligands, thereby indicating an energy-dependent receptor-mediated endocytotic pathway. Accordingly, the interaction of HBV-pres! with this specific B-cell line may serve as an effective model for an infection pathway in extrahepatic cells.

• 전자공학회논문지 IE
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• 제46권1호
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• pp.7-15
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• 2009

본 논문에서는 지상라이다를 이용한 구조물의 자동 윤곽선 추출을 다룬다. 본 논문에서는 사진을 이용하지 않고 전처리를 하지 않은 데이터를 직접 이용하여 구조물의 정면 윤곽선을 추출하는 것을 제안한다. 또한, 구조물의 크기와 데이터 수 즉, 라이다로 측정한 포인트 수를 고려한 효율적인 데시메이션 방법을 제안하였다. 이렇게 데시메이션된 데이터에서 라이다 데이터의 주요 특성중 하나인 거리정보를 이용하여, 구조물과 구조물이 아닌 점으로 구별해낸다. 그 후, 분산을 이용해 지역적으로 절대 좌표값이 큰 값과 작은 값을 찾아내고, 이를 윤곽선 후보 점으로 한다. 이렇게 찾아낸 구조물 윤곽선의 후보점들을 이어 윤곽선으로 만들고 최종적으로 정리하여 좀 더 현실에 가까운 윤곽선을 자동으로 추출하는 방법을 제안한다.

• 전자공학회논문지CI
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• 제38권2호
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• pp.27-32
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• 2001

본 논문은 패러렐 카메라 모델을 사용한 카메라 캘리브레이션과 3차원 스캐닝 알고리즘에 관한 것이다. 레이저 스트립라인이 스테레오 매칭을 위해 보조적으로 사용하였으나 원리적으로는 불필요하다. 피측정 물체는 스뎀핑모터에 의해 플레이트 위에서 360도 회전하며, 카메라로부터 거리를 측정하여 월드좌표를 구한다. 피측정 물체의 월드좌표는 모델좌표로 변환되며 다수의 군집 모델좌표로부터 모델링을 위한 면을 추출하고 OpenGL을 이용하여 렌더링 한다. 본 알고리즘은 에피폴라 라인의 매칭점의 유효성을 검사하여 잘못된 매칭값을 버리고 무효한 매칭값은 유효한 값으로부터 보간법으로 산출한다.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1996년도 춘계공동학술대회논문집; 공군사관학교, 청주; 26-27 Apr. 1996
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• pp.662-666
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• 1996

The variations of the surface topographical parameters for the analysis of the pedestrian slip and fall accidents during the sliding friction between the specially prepared floor specimens and three working shoes were investigated. The profile ordinate data for each flooring specimen were obtained at 1.1 .mu.m intervals using a laser scanning confocal microscope system along to the direction of sliding. A number of surface roughness parameters, that is, the centre line average (c.l.a.) and root mean square (r.m.s.) roughness, maximum height (Rtm), maximum mean peak height (Rpm), maximum mean depth (Rvm), and average asperity slope were calculated using a computer program and compared with the dynamic friction results. The analysis showed that the surface parameters undergo marked variations during the sliding process, but the variations were statistically significant. It was found that amongst various surface parameters, the maximum depth (Rvm) and the average asperity slope of the asperities were the biggest variation during the sliding proceeding. This result confirms the previous study and may suggests a new approach to monitoring the flooring environments with their service as the effort to reduce the pedestrain slip accident.

• Journal of Welding and Joining
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• 제18권4호
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• pp.70-75
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• 2000

The weld seam tracking system for arc welding process uses various kinds of sensors such as arc sensor, vision sensor, laser displacement and so on. Among the variety of sensors available, electro-magnetic sensor is one of the most useful methods especially in sheet metal butt-joint arc welding, primarily because it is hardly affected by the intense arc light and fume generated during the welding process, and also by the surface condition of weldments. In this study, a dual-electromagnetic sensor, which utilizes the induced current variation in the sensing coil due to the eddy current variation of the metal near the sensor, was developed for arc welding of sheet metal butt-joints. The dual-electromagnetic sensor thus detects the offset displacement of weld line from the center of sensor head even though there's no clearance in the joint. A set of design variables of the sensor were determined for the maximum sensing capability through the repeated experiments. Seam tracking is performed by correcting the position of sensor to the amount of offset displacement every sampling period. From the experimental results, the developed sensor showed the excellent capability of weld seam detection when the sensor to workpiece distance is near less than 5 mm, and it was revealed that the system has excellent seam tracking ability for the butt-joint of sheet metal.

• 한국BIM학회 논문집
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• 제9권4호
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• pp.10-20
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• 2019

As a result, the areas of knowledge that received the highest score in a positive impact were areas of risk management, while those that received the highest score in a negative impact were items of software management. In addition, each project was rated according to the score obtained. The distribution of grades by project was 71% for projects above middle grade and 29% for projects below middle grade. These results show that interest in BIM technology is increasing compared to the past, actual field application and research are actively being conducted, and that real construction sites also enjoy significant positive effects in terms of project management through BIM. In addition, the company is using BIM by applying advanced digital technologies such as AI technology, laser scanning technology and drone technology in line with the era of the fourth industrial revolution. Such a steady progress in future research on BIM technology development will reduce the number of low-grade projects and many middle-grade projects are expected to be upgraded to higher-level ones.

• 한국기계가공학회지
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• 제21권5호
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• pp.91-97
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• 2022

The Directed Energy Deposition (DED) is a representative metal additive manufacturing method. Owing to its strong point of repairment, its application is gradually spreading in aerospace applications, power generation, military components, and mold making. 5-axis cladding is needed to repair damage, such as wear and scratches on cylindrical surfaces to circular-shaped parts, including sleeves and liners. Furthermore, the condition of cladding on inclined parts must also be considered to prevent interference between the nozzle and the part. In this study, the effects of changes in scanning speed due to the 5-axis control system and differences from the height of laser beam irradiation due to inclination are evaluated among the items that should be additionally considered in 5-axis cladding compared to 3-axis cladding. Moreover, the trends of the width and height of the clad are identified by different tilting angles via single line cladding. Lastly, cladding methods on cylindrical surfaces at various angles are proposed to enhance the clad quality and post-processing efficacy. These results can be applied with 5-axis cladding on inclined surfaces, including cylindrical surfaces.

• International Journal of Korean Welding Society
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• 제2권2호
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• pp.51-56
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• 2002

The weld seam tracking system for arc welding process uses various kinds of sensors such as arc sensor, vision sensor, laser displacement sensor and so on. Among the variety of sensors available, electro-magnetic sensor is one of the most useful methods especially in sheet metal butt-joint arc welding, primarily because it is hardly affected by the intense arc light and fume generated during the welding process, and also by the surface condition of weldments. In this study, a dual-electromagnetic sensor, which utilizes the induced current variation in the sensing coil due to the eddy current variation of the metal near the sensor, was developed for arc welding of sheet metal I-butt joints. The dual-electromagnetic sensor thus detects the offset displacement of weld line from the center of sensor head even though there's no clearance in the joint. A set of design variables of the sensor was determined far the maximum sensing capability through the repeated experiments. Seam tracking is performed by correcting the position of sensor to the amount of offset displacement every sampling period. From the experimental results, the developed sensor showed the excellent capability of weld seam detection when the sensor to workpiece distance is near less than 5 ㎜, and it was revealed that the system has excellent seam tracking ability for the I-butt joint of sheet metal.