• 전자공학회논문지S
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• 제36S권11호
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• pp.79-88
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• 1999

본 논문은 움직이는 물체가 존재하는 영상열에서 특정 물체만을 계속 추적하고자 하는 방법을 제안하였다. 밝기값과 동작(motion)경계점에 기반을 둔 윤곽선(contour) 추적 알고리즘을 이용하였다. 영상에서 움직이는 물체의 윤곽선의 동작은 이동, 회전, 크기변화를 나타내는 아핀 동작 모델에 의해 잘 묘사되어짐을 가정한다. 움직이는 물체의 윤곽선은 영상열을 따라 추정되는 B-스플라인에 의해 위치와 동작이 표현된다. 패턴인식을 이용하여 추적하고자하는 물체인지를 판별한다. 선형 칼만 필터를 사용하기 위해 아핀 동작 매개변수와 움직이는 물체의 윤곽선 모양(shape)의 두 필터로 추정과정을 나누었다. 차량계기판을 대상으로 한 실험영상에서 이 방법을 이용하여 방해물체가 존재하는 경우에도 안정된 동작의 추정과 추적된 궤적의 획득이 가능함을 보였다.

• The Journal of Advanced Prosthodontics
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• 제10권5호
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• pp.388-394
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• 2018

PURPOSE. To measure axial displacement of different implant-abutment connection types and materials during screw tightening at the recommended torque by using a contact scanner for two-dimensional (2D) and three-dimensional (3D) analyses. MATERIALS AND METHODS. Twenty models of missing mandibular left second premolars were 3D-printed and implant fixtures were placed at the same position by using a surgical guide. External and internal fixtures were used. Three implant-abutment internal connection (INT) types and one implant-abutment external connection (EXT) type were prepared. Two of the INT types used titanium abutment and zirconia abutment; the other INT type was a customized abutment, fabricated by using a computer-controlled milling machine. The EXT type used titanium abutment. Screws were tightened at $10N{\cdot}cm$, simulating hand tightening, and then at the manufacturers' recommended torque ($30N{\cdot}cm$) 10 min later. Abutments and adjacent teeth were subsequently scanned with a contact scanner for 2D and 3D analyses using a 3D inspection software. RESULTS. Significant differences were observed in axial displacement according to the type of implant-abutment connection (P<.001). Vertical displacement of abutments was greater than overall displacement, and significant differences in vertical and overall displacement were observed among the four connection types (P<.05). CONCLUSION. Displacement according to connection type and material should be considered in choosing an implant abutment. When adjusting a prosthesis, tightening the screw at the manufacturers' recommended torque is advisable, rather than the level of hand tightening.

• 한국기계가공학회지
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• 제19권7호
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• pp.7-15
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• 2020

Recently, the fourth industrial revolution has been presented as a new paradigm and additive manufacturing (AM) has become one of the most important topics. For this reason, process monitoring for each cross-sectional layer of additive metal manufacturing is important. Particularly, deep learning can train a machine to analyze, optimize, and repair defects. In this paper, image classification is proposed by learning images of defects in the metal cross sections using the convolution neural network (CNN) image labeling algorithm. Defects were classified into three categories: crack, porosity, and hole. To overcome a lack-of-data problem, the amount of learning data was augmented using a data augmentation algorithm. This augmentation algorithm can transform an image to 180 images, increasing the learning accuracy. The number of training and validation images was 25,920 (80 %) and 6,480 (20 %), respectively. An optimized case with a combination of fully connected layers, an optimizer, and a loss function, showed that the model accuracy was 99.7 % and had a success rate of 97.8 % for 180 test images. In conclusion, image labeling was successfully performed and it is expected to be applied to automated AM process inspection and repair systems in the future.

• Structural Engineering and Mechanics
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• 제65권2호
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• pp.129-139
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• 2018

Post-tensioning (PT) tendons are commonly used for the assembly of modularized concrete members, and tension is applied to the tendons during construction to facilitate the integrated behavior of the members. However, the tension in a PT tendon decreases over time due to steel corrosion and concrete creep, and consequently, the stress on the anchor head that secures the PT tendon also diminishes. This study proposes an automatic detection system to identify tension reduction in a PT tendon using pulsed-eddy-current (PEC) measurement. An eddy-current sensor is installed on the surface of the steel anchor head. The sensor creates a pulsed excitation to the driving coil and measures the resulting PEC response using the pick-up coil. The basic premise is that the tension reduction of a PT tendon results in stress reduction on the anchor head surface and a change in the PEC intensity measured by the pick-up coil. Thus, PEC measurement is used to detect the reduction of the anchor head stress and consequently the reduction of the PT tendon force below a certain threshold value. The advantages of the proposed PEC-based tension-reduction-detection (PTRD) system are (1) a low-cost (< $ 30), low-power (< 2 Watts) sensor, (2) a short inspection time (< 10 seconds), (3) high reliability and (4) the potential for embedded sensing. A 3.3 m long full-scale monostrand PT tendon was used to evaluate the performance of the proposed PTRD system. The PT tendon was tensioned to 180 kN using a custom universal tensile machine, and the tension was decreased to 0 kN at 20 kN intervals. At each tension, the PEC responses were measured, and tension reduction was successfully detected.

• Journal of Biosystems Engineering
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• 제39권2호
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• pp.142-149
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• 2014

Purpose: A multispectral algorithm for detection and differentiation of defective (defects on apple skin) and normal Red Delicious apples was developed from analysis of a series of hyperspectral line-scan images. Methods: A fast line-scan hyperspectral imaging system mounted on a conventional apple sorting machine was used to capture hyperspectral images of apples moving approximately 4 apples per second on a conveyor belt. The detection algorithm included an apple segmentation method and a threshold function, and was developed using three wavebands at 676 nm, 714 nm and 779 nm. The algorithm was executed on line-by-line image analysis, simulating online real-time line-scan imaging inspection during fruit processing. Results: The rapid multispectral algorithm detected over 95% of defective apples and 91% of normal apples investigated. Conclusions: The multispectral defect detection algorithm can potentially be used in commercial apple processing lines.

• 한국정밀공학회지
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• 제27권2호
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• pp.70-77
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• 2010

This study proposed an auto focusing method for a multi-focus image in assembling lens modules in digital camera phones. A camera module in a camera phone is composed of a lens barrel, an IR glass, a lens mount, a PCB board and aspheric lenses. Alignment among the components is one of the important factors in product quality. Auto-focus is essential to adjust image quality of an IR glass in a lens holder, but there are two focal points in the captured image due to thickness of IR glass. So, sharpness, probability and a scale factor are defined to find desired focus from a multi-focus image. The sharpness is defined as clarity of an image. Probability and a scale factors are calculated using pattern matching with a registered image. The presented algorithm was applied to a lens assembly machine which has 5 axes, two vacuum chucks and an inspection system. The desired focus can be determined on the local maximum of the sharpness, the probability and the scale factor in the experiment.

• 한국환경과학회지
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• 제19권6호
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• pp.747-753
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• 2010

It follows in quality and sewage exclusion method of the investigation objective sector and the Combined Sewer Overflows which is suitable in regional characteristics and the confluence area against the rainfall initially a flow and the medulla and measurement - it analyzes the initial rainfall outflow possibility control plan which is suitable in the domestic actual condition and it proposes the monitor ring plan for the long-term flow and pollution load data accumulation. From the research which it sees the Infiltration water/Influent water and CSOs investigation it passes by the phase of hazard chain and Namwon right time 4 it does not hold reverse under selecting, Measurement it used the hazard automatic flow joint seal Sigma 910 machine and in case 15 minute interval of the I/I, it measured a flow at case 5, 15 minute standing of the CSOs. The water quality investigation for the water leakage investigation of the I/I and the sewage from the point which is identical with flow measurement during on-the-spot inspection duration against 6 items which include the BOD sampling and an analysis, when the rainfall analysis for CSOs fundamental investigation analyzed against 18 items which include the BOD sampling. Consequently, for the optimum interpretation invasion water / inflow water of the this investigation area day average the lowest flow - water quality assessment veterinarian optimum interpretation hazard average per day - lowest flow - it averages a medulla evaluation law department one lowest flow evaluation technique and it selects, it presentation collectively from here it gets, position result with base flow analysis of invasion water / inflow water.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 추계종합학술대회
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• pp.363-366
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• 2001

현재 육안에 의한 피혁의 등급 판정 과정은 장시간 시 피로에 의한 일관성 결여로 인해 판정 결과에 대한 신뢰성을 주지 못한다. 따라서 피혁의 품질을 결정하기 위한 객관적인 지표와 이를 기준으로 등급 판정 과정의 자동화가 필요하다. 본 논문에서 적용된 피혁 자동 선별 시스템은 피혁에 대한 정보를 취득하는 과정과 이들 정보로부터 등급을 판정하는 과정으로 구성된다. 피혁의 품질은 조밀도와 결함의 종류 및 분포도와 같은 피혁 정보에 의해 결정된다. 본 논문에서는 디지털 카메라에 의해 획득된 흑백 영상으로부터 피혁의 조밀도 및 결함에 대한 정보를 추출하는 알고리즘을 제안한다. 조밀도에 대한 정보는 원 영상을 주파수 영역으로 변환한 후 나타나는 퓨리에 스펙트럼 분포의 특징 값들에 의해서 추출된다. 그리고 결함에 대한 정보는 전처리 과정을 거친 영상으로부터 경계선 검출 후 검색 윈도우를 사용하여 윈도우에 해당하는 픽셀들의 통계적 수치에 의해서 검출된다. 피혁 전체에 대한 정보들은 피혁의 등급을 판정하는 지표로 사용되며 실제 머신 비젼 시스템에 적용된다.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2007년도 정기학술발표대회 논문집
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• pp.450-454
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• 2007

최근 건설업의 대형화, 복잡화됨에 따라 안전사고가 증가하고 있다. 특히, 건설장비에 의한 사고 발생수가 증가하고 있다. 이런 사고의 예방을 위해서는 발생원인을 분석할 필요가 있다. 본 논문은 한국산업안전공단의 건설재해사례를 통해 안전사고 원인을 분석한다. 연구의 범위는 굴삭기 장비로 한정하였다. 본 연구의 결과를 요약하면 다음과 같다. 1) 굴삭기 재해 발생 형태는 협착${\cdot}$감김, 낙하${\cdot}$비래, 충돌${\cdot}$접촉 순으로 분석되었따. 2) 재해원인은 작업반경 내에 근로자출입, 주용도 이외의 용도로 사용함, 작업시작 전 저멈불량${\cdot}$ 작업방법불량 순으로 분석되었다. 이 연구결과는 차후 연구의 기초를 정립하고, 안전사고를 줄이는 기대효과를 가질 것이다.

• 한국정보통신학회논문지
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• 제22권3호
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• pp.499-505
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• 2018

전 세계적으로 해운물류 안전 보안체계가 강화됨에 따라 국가물류보안 체계 구축을 위한 해운물류안전 보안 핵심기술 개발이 이루어지고 있다. 또한 미국에서 2018년 시행예정인 컨테이너 사전 100% 전수검사에 대응하기 위한 컨테이너 검색기의 핵심구성 요소인 Array 검출 시스템의 국산화 개발이 필요하다. 본 논문에서는 현재 자체 개발한 Test Digital 신호처리 Board를 가지고 TI-RTOS(Texas Instruments - Real Time Operating System)를 이용하여 개발한 Test Software Program을 제안한다. M4 MCU를 기반으로 GPIO, SRAM, TCP/IP와 SDcard등을 테스트 할 수 있는 프로그램을 개발했다. 또한 Array 검출 system 중 자체 개발한 Digital Signal Processing Board에 대한 연구를 제안하고자 한다. M4 MCU를 테스트 할 수 있는 테스트보드를 개발했고 FPGA와 MCU가 결합된 통한 X-RAY 디지털 신호처리 보드를 개발했다.