• The Journal of the Korean dental association
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• v.52 no.8
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• pp.456-463
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• 2014

Caries Management by Risk Assessment (CAMBRA), published by California Dental Association in 2003, is a customized caries care system that classifies individuals' caries risk into 4 risk groups based on objective evidences and provides chemical treatments targeted for each caries risk level. However, this system was not only developed but also optimized for situation in the United States, resulting into many limitations to be used in Korea, and thus Korean CAMBRA (K-CAMBRA) that considers the clinical situation in Korea needs to be developed. K-CAMBRA includes various techniques that are newly developed in order to overcome the limitations. First, Q-ray, a new optical technology, is utilized in order to avoid the subjectivity of visual inspection during assessment of disease indicators and risk factors. Moreover, Cariview? that reflects the paradigm shift in cariology as a new form of caries assessment kit is used. In addition, considering the situation in Korea, where it is impossible to use high concentration fluoride product, Oral pack with a customized tray is added to increase the contact time of chemical substance. CAMBRA is believed to be the key clinical tool that overcomes the limitations of the paradigm of the conventional restoration-based surgical model of dentistry. Furthermore, it can be expected that Korean dentists can act as oral physicians who are able to control and care individuals' caries risk rather than operative experts who only care about the outcome of caries.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.4
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• pp.1233-1240
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• 1996

Conventional measurement methods using ultrasonic wave or x-ray, eddy current for non-destructive testing(NDT) in nuclear power plants and other industrial plants have been utilized as the method of contact with objects to be inspected. For this reason these methods require relatively much time and inspection area is limited by the location of probe or film. But holograpic interferometry which is a non-contact optical measurement method using a coherent light source has an advantage that quantative measurement can be performed at a time. In this paper a new method using realtime holographic interfreometry and image processing for detecting internal flaws of pressure vessels is presented.

• Journal of Korea Society of Industrial Information Systems
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• v.13 no.1
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• pp.22-29
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• 2008

This paper describes the developed results of vision system for the recognition of material management characters, which was included in the billet image. The material management characters, which was marked at the surface of billet, should be recognized before billet moves to the next process. Our vision system for the character recognition includes that CCD camera system which acquire billet image, optical transmission system which transmit captured image to the long distance, input and output system for the interface with existing system and software for the character recognition. We have installed our vision system at the wire rod line of steel & iron plant and tested. Also, we have performed inspection of durability, reliability and recognition rate. Through the testing, we have confirmed that our system have high recognition rate, 98.6%.

• Journal of the Semiconductor & Display Technology
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• v.20 no.3
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• pp.6-10
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• 2021

Recognition of characters printed or marked on the PCB components from images captured using cameras is an important task in PCB components inspection systems. Previous optical character recognition (OCR) of PCB components typically consists of two stages: character segmentation and classification of each segmented character. However, character segmentation often fails due to corrupted characters, low image contrast, etc. Thus, OCR without character segmentation is desirable and increasingly used via deep neural networks. Typical implementation based on deep neural nets without character segmentation includes convolutional neural network followed by recurrent neural network (RNN). However, one disadvantage of this approach is slow execution due to RNN layers. LPRNet is a segmentation-free character recognition network with excellent accuracy proved in license plate recognition. LPRNet uses a wide convolution instead of RNN, thus enabling fast inference. In this paper, LPRNet was adapted for recognizing characters printed on PCB components with fast execution and high accuracy. Initial training with synthetic images followed by fine-tuning on real text images yielded accurate recognition. This net can be further optimized on Intel CPU using OpenVINO tool kit. The optimized version of the network can be run in real-time faster than even GPU.

• Current Optics and Photonics
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• v.6 no.2
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• pp.161-170
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• 2022

Three-dimensional (3D) geometric models are introduced to correct vignetting, and a downhill simplex search is applied to determine the coefficients of a 3D model used in digital microscopy. Vignetting is nonuniform illuminance with a geometric regularity on a two-dimensional (2D) image plane, which allows the illuminance distribution to be estimated using 3D models. The 3D models are defined using generalized polynomials and arbitrary coefficients. Because the 3D models are nonlinear, their coefficients are determined using a simplex search. The cost function of the simplex search is defined to minimize the error between the 3D model and the reference image of a standard white board. The conventional and proposed methods for correcting the vignetting are used in experiments on four inspection systems based on machine vision and microscopy. The methods are investigated using various performance indices, including the coefficient of determination, the mean absolute error, and the uniformity after correction. The proposed method is intuitive and shows performance similar to the conventional approach, using a smaller number of coefficients.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.01a
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• pp.185-186
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• 2021

기존의 건물 점검은 사람이 직접 들어가 확인하는 방식이 일반적이다. 본 연구에서는 건물 탐사를 보다 안전하고 신속하게 하는 것을 전제로 하여 현재 상용화 되고 있는 드론과 아두이노를 이용한 센서를 적용하고자 한다. 건물 점검은 사람이 직접 들어가 확인하는 만큼 안전 수칙을 지켜가며 실시해야 하지만, 불편함이나 귀찮음을 핑계로 지켜지지 않는 경우가 대다수이다. 지켜지지 못한 안전 수칙에 더불어, 건물의 직접적인 상태를 미리 알지 못하고 진입하게 됨으로 발생하는 인명피해는 불가피하다. 본 논문은 이러한 문제점들을 개선하기 위해 기존의 어려운 조작의 드론에 호버링이 가능하게 하는 옵티컬 플로어 센서를 장착하여 조작을 보다 쉽게 하고 아두이노의 센서를 적용한 '건물 탐사 드론' 기술을 제안한다. 기존의 드론과 다르게 카메라와 센서를 이용해 건물의 점검을 대신하고, 센서들의 값을 앱으로 전송받아 핸드폰으로 받아 볼 수 있다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.01a
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• pp.3-5
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• 2022

본 연구는 VGGNet을 사용하여 광섬유 복합가공 지선 설비의 양/불량 판별을 수행한다. 광섬유 복합가공 지선이란, 전력선의 보호 및 전력 시설 간 통신을 담당하는 중요 설비로 고장 발생 전, 결함의 조기 발견 및 유지 관리가 중요하다. 현재 한국전력공사에서는 드론에서 촬영된 영상을 점검원이 이상 여부를 점검하는 방식이 주로 사용되고 있으나 이는 점검원의 숙련도, 경험에 따른 정확성 및 비용과 시간 측면에서 한계를 지니고 있다. 본 연구는 드론에서 촬영된 영상으로 VGGNet 기반의 양/불량 판정을 수행했다. 그 결과, 정확도 약 95.15%, 정밀도 약 96%, 재현율 약 95%, f1 score 약 95%의 성능을 확인하였다. 결과 확인 방법으로는 설명 가능한 인공지능(XAI) 알고리즘 중 하나인 Grad-CAM을 적용하였다. 이러한 광섬유 복합가공 지선 설비의 양/불량 판별은 점검원의 단순 작업에 대한 비용 및 점검 시간을 줄이며, 부가가치가 높은 업무에 집중할 수 있게 해준다. 또한, 고장 결함 발견에 있어서 객관적인 점검을 수행하기 때문에 일정한 점검 품질을 유지한다는 점에서 적용 가치가 있다.

• Journal of Korean Public Health Nursing
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• v.4 no.2
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• pp.59-77
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• 1990

The purpose of this study was to provide the basic data for the effective health management of the industrial workers, by classifying factors influencing their perceived symptoms to examine their health status and identifying the inter' relationship of their perceived symptom with their working department. the environment of working area and their general characteristics. The study was undertaken from October 1 to November 30. 1989. The subjects were 999 workers who had worked in Industrial Corps located in Chungbuk Province. The results of this study were as follows: I . Worker's perceived symptoms were classified according to the following eight factors; 1) musculo - skeletal symptoms of shoulder, neck, back and arm 2) optical symptoms 3) symptoms in head(such as headache and dull) 4) musculo - skeletal symptoms of leg and lower back 5) gastro - intestinal symptoms 6) mental symptoms. 7) neural symptoms 8) lung and heart symptoms II . The degrees of workers' perception of perceived symptoms; Mean score of perceived symptoms:7.0 The rank of degrees of perceived symptoms: The highest:musculo - skeletal symptoms of shoulder, neck, back, and arm The second:optical symptoms The third:musculo - skeletal symptoms of leg and lower back The fourth:mental symptoms the fifth:gastro-intestinal symptoms m . Analysis of the inter-relationship of perceived symptoms with working department, environment of working area and general characteristics; 1) sexuality The difference of degrees of perceived symptoms was significant;femanle was higher than male(P<0.000). 2) level of education The difference of degrees of perceived symptoms according to the level of education was significant; The higher the level of education, the higher the degree. 3) working department The working department played a significant part in the degrees of perceived symptoms of workers; Workers of assembling department:musculo-skeletal symptoms both of shoulder. neck, back and arm and of leg and lower back(P<0.000). Workers of inspection department:optical symptoms(P<0.05). Office workers:mental symptoms(P<0.05). 4) kinds of job The difference of the degrees of perceived symptoms according to kinds of job was significant; Workers dealing with chemical materials and workers dealing with job with high tension:gastro-intestinal symptoms and symptoms in head. Workers dealing with weighty things or working a long time with the same posture:musculo-skeletal symptoms both of shoulder, neck, back and arm and of lower back(P<0.000). 5) working posture The difference of the degrees of perceived symptoms related with working posture was significant; Sitting:optical symptoms(P<0.0000) and symptoms in head(P<0.005) Standing:musculo-skeletal symptoms of leg and lower back(P<0.0000). 6) satisfaction with their own duty The more dissatisfien they were. the higher became the degrees of their perceived symptoms(P<0.0001). 7) satisfaction with their working condition The more dissatisfied with their working condition they were, the higher became the degrees of their perceived symptoms(P<0.001). 8) environment of working area The environment of working area played a significant part in the degrees of perceived symptoms of workers; Workers exposed to most of the factors of the environment of working area were higher than those not exposed in the degrees of musculoskeletal symptoms. Workers in the noisy environment:optican symptoms(P<0.000), symptoms in head(P<0.005). Workers in the damp environment:optical symptoms(P<0.005) and lung and heart symptoms(P <0.01). Workers with illumination problem:optical symptoms(P<0.000), mental symptoms(P<0.005) and neural symptoms(P<0.01). Workers with ventilation problem:optical symptoms and lung and heart symptoms(P<0.001)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.598-603
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• 2019

Three-dimensional shape measurement technology is used in various industries. Among them, optical three-dimensional shape measurement techniques based on the optical trigonometry are mainly used in the field of semiconductor product inspection, where large quantities of three-dimensional shape measurements are made daily in factories and fine measurements are also required. The light source and the drive circuit, which are components of three-dimensional measurement equipment based on this optical trigonometry, produce heat generated by prolonged operation, and may be exposed to conditions where the ambient temperature is not constant, resulting in temperature-induced measurement errors. In this study, the compensation method of the Thermal Errors for Phase Measuring Profilometry is proposed. Three-Dimensional Shape Measurement Equipment based on Phase Measuring Profilometry is implemented to measure the height of an object and ambient temperature for 10 Hours, and a regression line was obtained line by making simple linear regression using measured temperature and height values. This regression line was used to correct the error of the height measurement according to the temperature, and thermal error was from 139.88 um(Micrometer) to 13.12 um.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.12
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• pp.1704-1710
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• 2020

The high-energy X-ray imaging detector used for container inspection uses a thick scintillator to effectively acquire X-rays. X-ray incident on the scintillator is generally up to 9MeV. Therefore, to effectively collect X-ray, it is necessary to use a thick scintillator. To collect the light generated by the reaction between X-ray and scintillator, an optical-sensor must be combined with the scintillator. In this study, a study on the design conditions of the detector using a CdWO4 and a small sensor is described. To calculate the collected light according to the change of the scintillator thickness and the reflectance of surface, MCNP6 and DETECT2000 were used. As a result of calculating, it was confirmed that when the reflectance of the surface was low, it was appropriate to select a scintillator with a thickness of 15 to 20-mm, but as the reflectance increased, it was confirmed that it was appropriate to select a CdWO4 with a thickness of 25 to 30-mm.