• 대한전자공학회논문지
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• 제25권4호
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• pp.447-452
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• 1988

This paper proposes a hybrid image coding in order to improve the coding performance by combining the BTC with the DPCM. And utilizing the human perceptual characteristics, a new objective image quality evaluation method has been proposed to obtain an excellent result in good agreement with the subjective quality evaluation. A hyb-1 method consisting of the DPCM and the AMBTC has retained a good picture quality at the bit rate of 1.5 bits/pel. A hyb-3 method combining the EBTC-3 with the DPCM has scarcely degraded the picture quality compared with the original image at the bit rate of 2.1 bits/pel. A newly proposed mehtod of picture quality evaluation accumulating a blocky noise at the edge block and an impulsive noise at the flat block selectively has been coincident with the subjective evaluation of quality.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1228-1231
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• 2009

This paper presented an automatic system for display quality measurement by image processing. The goal is to replace human eyes for display quality evaluation by computer vision and get the objective quality review for consumer to make purchase of monitor or TV. Color, contrast, brightness, sharpness and motion blur are the main five factors to affect display quality that could be measured by supplying patterns and analyzing the corresponding images captured from webcam. The scores are calculated by image processing techniques. Linear regression model is then adopted to find the relation between human score and the measured display performance.

• 대한디지털의료영상학회논문지
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• 제14권2호
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• pp.47-56
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• 2012

Amount of radiation exposure by seeing through fluoroscopy examination while is many patient exposure administration and unprepared misgovernment be. In this study, abdominal fluoroscopy during the scan, the dose and image quality change according to the use of grid and added filter optimized by measuring the test condition is proposed. Uses seeing through fluoroscopy examination equipment of Image Intensifier of Easy Diagnost Eleva (Philips), under tube type and uses Human phantom and measures average area dose according to grid insertion existence and nonexistence and added filter kind change. Measure sum of 29 organ dose and effective dose through PCXMC imagination simulation program and image J program through noise, SNR, image distortion was measured. Resolution, sharpness, and analyzed using the MTF curves. Fluorography the grid to insert the filter thickness and thickening and increased the average area dose and organ doses and effective dose. In the case of spot examination, when inserted grid, average area dose and organ dose and effective dose increased. Filter thickens the average area dose decreased, but the organ doses and effective dose were increased when use 0.2mmCu+1mmAl filter, decreased slightly. Noise and SNR measurements without inserting the gird, if you do not use the added filter was the lowest and when measure the distortion, 0.1mmCu+1mmAl filter was no difference of image quality in case insert grid was judged that when did not use occasion added filter that do not use grid, difference of image quality does not exist. Did not show a big difference, according to the grid and uses of the added filter sharpness, and resolution. Patient dose increases with factors that reduce the quality of the image so reckless grid and the use of the added filter when abdominal fluoroscopy examination should be cautious in using.

• Imaging Science in Dentistry
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• 제49권2호
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• pp.139-151
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• 2019

Purpose: This study was performed to investigate the effect of exposure parameters on image quality obtained using a cone-beam computed tomography (CBCT) scanner and the relationship between physical factors and clinical image quality depending on the diagnostic task. Materials and Methods: CBCT images of a SedentexCT IQ phantom and a real skull phantom were obtained under different combinations of tube voltage and tube current (Alphard 3030 CBCT scanner, 78-90 kVp and 2-8 mA). The images obtained using a SedentexCT IQ phantom were analyzed technically, and the physical factors of image noise, contrast resolution, spatial resolution, and metal artifacts were measured. The images obtained using a real skull phantom were evaluated for each diagnostic task by 6 oral and maxillofacial radiologists, and each setting was classified as acceptable or unacceptable based on those evaluations. A statistical analysis of the relationships of exposure parameters and physical factors with observer scores was conducted. Results: For periapical diagnosis and implant planning, the tube current of the acceptable images was significantly higher than that of the unacceptable images. Image noise, the contrast-to-noise ratio (CNR), the line pair chart on the Z axis, and modulation transfer function (MTF) values showed statistically significant differences between the acceptable and unacceptable image groups. The cut-off values obtained using receiver operating characteristic curves for CNR and MTF 10 were useful for determining acceptability. Conclusion: Tube current had a major influence on clinical image quality. CNR and MTF 10 were useful physical factors that showed significantly associations with clinical image quality.

• 대한원격탐사학회지
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• 제36권5_2호
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• pp.907-916
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• 2020

Images taken from airplanes, satellites and drones have been used in various realms, and the kinds and specifications of images are enlarged gradually. Despite the importance of images on diverse applications, the quality information of the images is controlled by each agency or institute respectively without any principle, or even is neglected, because the application of standards to the final products of image is not easy in Korea. We aim to review necessities and strategies for applying international standards on image and to suggest potential issues and possibilities to make standards in action.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1164-1167
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• 2009

Motion-image-quality of LCD-TVs is discussed by dynamic spatial frequency response. Smaller temporal aperture or higher frame rate can improve dynamic response, but an increase of motion velocity easily cancels the improvement. A guideline for deciding the desirable temporal aperture and frame rate of LCD-TVs is described, under the condition that camera and display have the same parameters. Two candidates of the desirable parameter sets will be (240 or 300 Hz, 50 to 100% aperture) and (120Hz, 25 to 50% aperture), from the viewpoint of "limit of acceptance" on motion-imagequality-deterioration for critical picture materials.

• 한국산업정보학회논문지
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• 제19권4호
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• pp.73-85
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• 2014

고객들이 지각하는 서비스 품질은 항공사에 대한 신뢰 및 이미지, 만족에도 긍정적 영향관계를 형성한다. 인적서비스와 비인적서비스의 제공은 소비자들의 항공사에 대한 전반적인 인상 및 긍정적 혹은 부정적 느낌을 형성하는 영향요소이며, 고객의 행동 의지까지 연결될 수 있다. 본 연구에서는 서비스 접점 품질에 대한 변수들을 인적서비스접점과 비인적서비스접점으로 구분하고 항공사 이미지와 지각된 가치, 애호도에 어떠한 영향을 미치는 지를 살펴보고자 한다. 연구결과 인적서비스 접점 품질은 항공사 이미지에 긍정적인 영향을 미치는 것으로 나타났으며 지각된 가치에는 부정적인 영향을 미치는 것으로 나타났다. 비인적서비스 접점 품질은 항공사 이미지에 긍정적인 영향을 미치며 지각된 가치에는 부정적인 영향을 미치는 것으로 나타났다. 또한 인적서비스 접점 품질은 고객 애호도에 유의한 영향을 미치지 않는 것으로 나타났으나, 비인적서비스 접점 품질은 고객 애호도에 유의한 영향을 미치는 것으로 나타났다. 항공사 이미지는 지각된 가치에 유의한 영향을 미치지 않는 것으로 나타났지만 고객 애호도에는 긍정적인 영향을 미치는 것으로 나타났다. 마지막으로 지각된 가치는 고객 애호도에 유의한 영향을 미치지 않는 것으로 나타났다.

• 한국해양공학회지
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• 제36권1호
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• pp.32-40
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• 2022

Underwater optical images face various limitations that degrade the image quality compared with optical images taken in our atmosphere. Attenuation according to the wavelength of light and reflection by very small floating objects cause low contrast, blurry clarity, and color degradation in underwater images. We constructed an image data of the Korean sea and enhanced it by learning the characteristics of underwater images using the deep learning techniques of CycleGAN (cycle-consistent adversarial network), UGAN (underwater GAN), FUnIE-GAN (fast underwater image enhancement GAN). In addition, the underwater optical image was enhanced using the image processing technique of Image Fusion. For a quantitative performance comparison, UIQM (underwater image quality measure), which evaluates the performance of the enhancement in terms of colorfulness, sharpness, and contrast, and UCIQE (underwater color image quality evaluation), which evaluates the performance in terms of chroma, luminance, and saturation were calculated. For 100 underwater images taken in Korean seas, the average UIQMs of CycleGAN, UGAN, and FUnIE-GAN were 3.91, 3.42, and 2.66, respectively, and the average UCIQEs were measured to be 29.9, 26.77, and 22.88, respectively. The average UIQM and UCIQE of Image Fusion were 3.63 and 23.59, respectively. CycleGAN and UGAN qualitatively and quantitatively improved the image quality in various underwater environments, and FUnIE-GAN had performance differences depending on the underwater environment. Image Fusion showed good performance in terms of color correction and sharpness enhancement. It is expected that this method can be used for monitoring underwater works and the autonomous operation of unmanned vehicles by improving the visibility of underwater situations more accurately.

• The Journal of Asian Finance, Economics and Business
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• 제8권10호
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• pp.177-185
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• 2021

The purpose of this paper is to examine whether service quality, student satisfaction, and university image mediate the relationship between university sustainability practices and student loyalty of the students in Ho Chi Minh City, Vietnam. To analyze the data, this study used a structural equation model to explore the relationships existing between constructs. A structured questionnaire comprising of 22 questions was used with 5 constructs. A total of 465 students from Ho Chi Minh City universities filled in the newly developed questionnaires using five points Likert scales. Consistent with the existing result, the study reveals a valuable insight on university sustainability practices toward student loyalty of the university. According to the findings, university sustainability practices have a positive direct impact on service quality, student satisfaction, university image, and student loyalty. And also service quality has a positive strong impact on student loyalty. Furthermore, service quality, student satisfaction, and university image play the mediating role in the relationship between university sustainability practices and student loyalty. Thus, the loyalty of students seems to reflect quite well from university sustainability practices, service quality, and university image. The findings indicate that universities should be more concerned about university sustainability practices, service quality, and university image in attracting student loyalty.

• 한국방사선학회논문지
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• 제15권5호
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• pp.621-628
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• 2021

혈관 내 초음파 카테터의 주파수 관련 화질 분석에 대한 선행 연구는 국내 국외 모두 미비한 실정이다. 따라서 프로그램을 이용해 영상 화질 측정 방법의 기준을 마련하여 혈관 내 초음파 영상의 화질 분석 관련 연구자들에게 측정 방법을 제안하고자 본 연구를 진행하게 되었다. 대상으로는 혈관 내강 크기가 3.0 - 4.0 mm를 대상으로 혈관 내 초음파를 사용하기 전 초음파 카테터에 공기나 이물질이 들어가지 않도록 충분히 세척해주고 니트로글리세린(NTG)을 관상동맥 내 200 micro를 투여해 혈관을 충분히 확장시킨 영상의 정상 혈관 영상과 병변 혈관 영상을 대상으로 하였다. 기준이 되는 영상 획득 방법으로는 혈관 내 초음파 사용 시 혈관 병변 평가가 가장 우수한 심장 수축기 끝 구간의 영상을 DCAS PACS 프로그램을 통해 후향적으로 획득하여 기준을 설정하였다. 측정 방법 기준 설정 시 정상 혈관과 병변 혈관의 동심원적 및 편심원적에 해당하는 기준 설정 방법을 제안하였고 이 기준을 적용하여 정상 혈관과 병변 혈관의 내강과 외강 관심 영역 및 배경 영역 측정 방법에 대해 제안하였다. 결론적으로 본 연구자들이 고안해낸 방법을 통해 혈관 내 초음파 촬영 영상의 화질을 측정한다면 혈관 내 초음파 카테터의 종류를 불문하고 일관성 있는 화질 측정 진행이 가능하다 생각한다. 따라서 혈관 내 초음파 영상 화질 관련 연구 시 실제 화질 측정 방법에 대해 가이드라인으로 적용시킬 수 있을 것으로 사료된다.