• Imaging Science in Dentistry
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• 제45권3호
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• pp.141-145
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• 2015

Purpose: This study evaluated the diagnostic accuracy of the reverse contrast mode in intraoral digital radiography for the detection of proximal dentinal caries, in comparison with the original digital radiographs. Materials and Methods: Eighty extracted premolars with no clinically apparent caries were selected, and digital radiographs of them were taken separately in standard conditions. Four observers examined the original radiographs and the same radiographs in the reverse contrast mode with the goal of identifying proximal dentinal caries. Microscopic sections $5{\mu}m$ in thickness were prepared from the teeth in the mesiodistal direction. Four slides prepared from each sample used as the diagnostic gold standard. The data were analyzed using SPSS (${\alpha}=0.05$). Results: Our results showed that the original radiographs in order to identify proximal dentinal caries had the following values for sensitivity, specificity, positive predictive value, negative predictive value, and accuracy, respectively: 72.5%, 90%, 87.2%, 76.5%, and 80.9%. For the reverse contrast mode, however, the corresponding values were 63.1%, 89.4%, 87.1%, 73.5%, and 78.8%, respectively. The sensitivity of original digital radiograph for detecting proximal dentinal caries was significantly higher than that of reverse contrast mode (p<0.05). However, no statistically significant differences were found regarding specificity, positive predictive value, negative predictive value, or accuracy (p>0.05). Conclusion: The sensitivity of the original digital radiograph for detecting proximal dentinal caries was significantly higher than that of the reversed contrast images. However, no statistically significant differences were found between these techniques regarding specificity, positive predictive value, negative predictive value, or accuracy.

• Journal of the Optical Society of Korea
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• 제18권6호
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• pp.809-817
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• 2014

The loss in contrast-discrimination ability of the human visual system under high ambient illumination level can cause image quality degradation in mobile phones. In this paper, we propose a perceived contrast compensation method by processing the original displayed image. With consideration that the perceived contrast significantly varies across the image, this method extracts the local band contrast from the original image; it then compensates these contrast components to counteract the perceived contrast degradation. Experimental results demonstrate that this method can maintain most contrast details even in high ambient illumination levels.

• Imaging Science in Dentistry
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• 제32권3호
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• pp.123-127
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• 2002

Purpose : To determine whether subtraction images utilizing contrast media can improve the diagnostic performance of proximal caries diagnosis compared to conventional periapical radiographic images. Materials and Methods: Thirty-six teeth with 57 proximal surfaces were radiographied using a size #2 RVG-ui sensor (Trophy Radiology, Marne-la-Vallee, France). The teeth immersed in water-soluble contrast media and subtraction images were taken. Each tooth was then sectioned for histologic examination. The digital radiographic images and subtraction images were examined and interpreted by three dentists for proximal caries. The results of the proximal caries diagnosis were then verified with the results of the histologic examination. Results: The proximal caries sensitivity using digital subtraction radiography was significantly higher than simply examining a single digital radiograph. The sensitivity of the proximal dentinal carious lesion when analyzed with the subtraction radiograph and the radiograph together was higher than with the subtraction radiograph or the radiograph alone. Conclusion: The use of subtraction radiography with contrast media may be useful for detecting proximal dentinal carious lesions.

• 대한의용생체공학회:의공학회지
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• 제30권5호
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• pp.412-417
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• 2009

The purpose of this study was to assess the ability of this device during clinically important episodes of extravasation. The extravasation detection accessory (EDA) system was based of infrared ray with detection sensor, an amplifier, alarm device, receiver, cable and a computer based system. This study was a prospective, observational study in which the EDA system was used to monitor the automated mechanical injection of contrast media. Three hundred patients referred for contrast media enhanced body computed tomography studied in a prospective, observation study in which the EDA system was used to identify and interrupt any injection associated with clinically important extravasation. There were 8 true-positive cases, 276 true-negative cases, 15 false-positive cases and 1 false-negative cases. The EDA system had a sensitivity of 88.8% and a specificity of 94.8% for the detection of clinically important extravasation. The EDA system had good sensitivity for the detection of clinically important extravasation and the EDA system has the clinical potential for the early detection of extravasation of the contrast medium that is administered with power injectors.

• 한국항행학회논문지
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• 제11권1호
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• pp.105-111
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• 2007

본 논문에서는 퍼지추론을 이용하여 워터마크가 삽입될 최적의 부 대역을 결정하는 방법을 기술하였다. 제안한 방법은 퍼지추론 및 대조도 등과 같은 인간의 시각시스템도 고려하였다. 먼저 시각시스템과 통계적 특성을 활용하여 최적의 계수 대역을 설정하였고, 외부환경 변화에도 대응할 수 있는 퍼지 추론기를 설계 하였다. 비가시성과 워터마크의 정확도를 실험한 결과, 대조도는 스므드 영상에서 우수하였고, 러프한 영상에서는 통계적 특성이 우수함을 보였다.

• 한국안광학회지
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• 제4권1호
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• pp.63-68
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• 1999

공간주파수에 따른 contrast sensitivity를 측정할 수 있는 새로운 방법으로 차트를 제작하기 위해 차트 화면 최대 luminance값을 100%로 하여, 격자주파수의 mean luminance를 25, 50, 75%의 3개형태로 만들어 CS값 0 에서 $10^3$ 값이 되도록 하였다. 초등학생 5학년을 대상으로 공간주파수에 따른 CS값의 측정결과 평균 luminance 값이 떨어질수록 CS값은 감소되고, peak 위치도 low spatial frequency 쪽으로 이동하였다. 약시인 사람은 고주파수쪽에서 CS가 감소하거나, 전체주파수 공간에서 CS값이 감소하였다. 격자순응에 의해 CS 측정값은 순응된 공간주파수의 주변 영역에서 CS가 감소된다.

• 한국콘텐츠학회논문지
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• 제13권11호
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• pp.562-570
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• 2013

이미지를 감성으로 쾌 또는 불쾌, 긴장 또는 평온의 구분 감성을 트리 형식으로 가중치를 부여하여 평가한다. 이미지 대표평가 감성인 명도대비를 평가 기준으로 1차는 쾌, 불쾌 또는 긴장 또는 평온이고 2차는 세분화 이미지 감성으로 구분한다. 4개의 감성인식을 수치화 된 명도대비 데이터로 측정한다. 평가 구현은 OpenCV를 통해 명도대비를 그래프화하여 긴장, 평온, 쾌, 불쾌 값 변화에 따라 4개 감성으로 구분하여 컴퓨팅한다. 감성 컴퓨팅으로 명도대비의 입력된 값에 따라 '불쾌'를 '쾌' 또는 '긴장'을 '평온'으로 감성적 변화를 줄 수 있다. 이미지 감성의 규칙성을 계산화 된 컴퓨팅 시스템으로 제어할 수 있고 향후 산업방향에 감성 인식의 적용에 대한 긍정적인 역할을 할 것이다.

• 말소리와 음성과학
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• 제2권3호
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• pp.91-99
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• 2010

This paper reports on an identification test where KFL learners identified the Korean three-way laryngeal contrast in the phrase-initial position, when the phrase-initial tone was systematically manipulated. It turns out that heritage learners have some sensitivity to phrase-initial tone and show a plain-aspirated alternation in their identification according to the phrase-initial tone, as native speakers do, whereas non-heritage students do not show such tone sensitivity. However, after a weekly prosody training, second-year non-heritage students have shown a significant improvement in their performance. This paper clearly shows that the phrase-initial tone plays a critical role in distinguishing laryngeal features of Korean obstruents, and also suggests that prosody including the tone-segment correlation should be incorporated in the KFL curriculum.

• Food Science and Biotechnology
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• 제17권5호
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• pp.1052-1059
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• 2008

Sequential Sensitivity Analysis (SSA) and conditional stimulus model have been developed to describe sequence effects in difference tests and proposed to generate prediction of differences in sensitivity between various test protocols and to assist the appropriate selection of difference test. Yet, such models did not furnish a complete explanation of the relative sensitivity in 4 different versions of 3-alternative forced choice (AFC) tests where various interstimulus rinses were introduced. In the present study, the vector of the contrasts between various conditional stimuli were measured using same-different and 2-AFC and a new 16-distribution conditional stimulus model was developed by refining Lee and O'Mahony's contrast model. This new model gave superior predictions than previous models.

• 디지털콘텐츠학회 논문지
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• 제6권2호
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• pp.119-123
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• 2005

본 논문에서는 HVS 기반 효과적인 워터마킹 방법을 제안하였다. 인간시각시스템의 파라미터로 명암대비, 텍스쳐, 엔트로피, 그리고 표준편차 등을 사용하였고, 외부공격에 대한 각 파라미터들의 성능을 평가한다. 실험결과, 스므드한 영상의 경우 명암대비 파라미터를 사용했을 때 워터마크의 추출이 좋았고, 거친 영상은 표준편차 파라미터에 강인함을 보였다. 결론적으로 영상의 특징에 맞는 파라미터를 선택하는 것이 효과적인 워터마킹을 위해 선행처리 되어야 한다.