• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.26 no.2
• /
• pp.191-200
• /
• 1996

This study was performed to determine the adequate resolution and compression method in teleradiology. A digital imaging system using Machintosh IT ci computer, 15' Sony high resolution RGB monitor, Umax Power look flatbed scanner with transparency unit and 12 panoramic radiographs were used. The results were as follows : 1. Relative detectability at the group scanned by 30ddpi, 600dpi and 1200dpi was same as those at the real panoramic radiographs. 2. Perceivable image quality degradation was found at the 25％ of middle quality of JPEG compression. But those were not diagnostically significant. 3. Perceivable image quality degradation was found at the 100％ of low quality of JPEG compression. And 8cases among them were diagnostically significant. On the basis of the above results, it is considered that the adequate resolution in scanning radiographs for teleradiology is 300dpi and compression method is the middle quality of JPEG compression.

• IEIE Transactions on Smart Processing and Computing
• /
• v.4 no.4
• /
• pp.251-257
• /
• 2015

This work presents modelling and simulation of a readout integrated circuit (ROIC) design considering pair-wise serial configuration along with thermal modeling of an uncooled microbolometer array. A fully differential approach is used at the input stage in order to reduce fixed pattern noise due to the process variation and self-heating-related issues. Each pair of microbolometers is pulse-biased such that they both fall under the same self-heating point along the self-heating trend line. A ${\pm}10%$ process variation is considered. The proposed design is simulated with a reference input image consisting of an array of $127{\times}92$ pixels. This configuration uses only one unity gain differential amplifier along with a single 14-bit analog-to-digital converter in order to minimize the dynamic range requirement of the ROIC.

• Information Display
• /
• v.15 no.5
• /
• pp.22-32
• /
• 2014

The current research intends to quantify the surround luminance effects on the shape of spatial luminance CSF and to propose an image quality evaluation method that is adaptive to both surround luminance and spatial frequency of a given stimulus. The proposed image quality method extends to a model called SQRI[8]. The non-linear behaviour of the HVS was taken into account by using CSF. This model can be defined as the square root integration of multiplication between display MTF and CSF. It is assumed that image quality can be determined by considering the MTF of the imaging system and the CSF of human observers. The CSF term in the original SQRI model was replaced by the surround adaptive CSF quantified in this study and it is divided by the Fourier transform of a given stimulus. A few limitations of the current work should be addressed and revised in the future study. First, more accurate model predictions can be achievable when the actual display MTF is measured and used instead of the approximation. Then, a further improvement to the model prediction accuracy can be made when chromatic adaptation of the HVS is taken into account[45-46].

• Journal of Biomedical Engineering Research
• /
• v.29 no.1
• /
• pp.46-51
• /
• 2008

We describe a backprojection filtering method for limited angle tomography. In order to reduce blur artifacts originated from the out-of-planes and control high-frequency noise, we employed two band-limited window functions, and which were realized by Hann filters in this study. Based on the experimentally measured data, the performance of the developed method is demonstrated by comparing with the conventional shift-and-add and filtered backprojection methods. Application of the developed method to the dental imaging has a potential to be used for the preoperative evaluation of the jaw for dental implants with much reduced patient dose instead of the conventional dental computed tomography.

• Proceedings of the KIEE Conference
• /
• 2006.07e
• /
• pp.37-38
• /
• 2006

In this paper, the fire characteristics of circuit breakers for low voltage during switching arcs were analyzed according to the characteristics of combustible materials. Arc dispersion and ignition process were taken by high speed imaging system and digital camera. In this experiment, four resistors were connected as loads. To discover the fire characteristics of circuit breakers by combustible materials, ethanol and cotton were installed as combustibles near contacts respectively. In case of ethanol, fire broke out near the contacts while switch was turned on and turned off. Whereas, in case of cotton, fire broke out near deteriorated contacts while switch was turned off.

• Proceedings of the Optical Society of Korea Conference
• /
• 2003.07a
• /
• pp.82-83
• /
• 2003

PC의 대량 보급과 인터넷 케이블 망의 전지역적 구축을 통해 디지털 정보의 교류가 활발히 이루어지고 있다. 이에 따라 아날로그 이미지를 디지털화 하는 디지털 카메라나 스캐너와 같은 이미지 입력 장치와, 디지털 이미지를 눈으로 볼 수 있게 하는 모니터나 프린터와 같은 이미지 출력 장치로 구성되는 디지털 이미징 장치들의 사용이 일상화되고 있다. TV나 컴퓨터 모니터를 통한 인터넷 상품 구매는 이미 보편화되어 있고, 스캐너를 사용하여 사진을 스캔하여 수정이나 합성 등의 편집을 한 후 이미지를 웹에 올리거나 사진 프린터로 다시 뽑는 일에도 익숙해져 있다. (중략)

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2014.05a
• /
• pp.47-48
• /
• 2014

Non-destructive technique to measure internal structure and constant distribution of material can be widely used to exploration of mineral resources, identification of underground cables and buried pipelines, and diagnostic imaging in medical area. In this paper, inverse scattering solution based on 2-dimensional EM scattering problem should be considered and formulated.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.49 no.9
• /
• pp.322-327
• /
• 2012

Parallel-plate-type scanning sensors have been commercially used for X-ray imaging sensors. In this study, we manufactured the scan typed 1D X-ray image sensor that can be used to obtain scanning images, by using the plasma display panel (PDP) fabrication process. We fabricated drift and pixel electrodes in the glass chamber and injected Xe gas at atmospheric pressure. We evaluated the intensity of a pixel signal depending on the bias voltage on the drift electrode and investigated the characteristics of shielding effect on the single pixel using lead (Pb). The adsorption rate of X-ray photon is low (4%) on the soda lime glass (1.1mm) and the electrical signal detected on the X-ray sensor was increased in the high bias voltage. We acquired digital X-ray scanning image with our DAS (data acquisition system) and sensor scanning system.

• Journal of the Korean Society of Radiology
• /
• v.10 no.2
• /
• pp.109-115
• /
• 2016

Despite of increasing the use of the digital imaging device in the radiology area, the setting on the optimal irradiation conditions are insufficient. In this study, the exposure dose and image quality by exposure condition of digital radiography device were compared. The exposure doses were obtained by adjusting the exposure condition as 5 steps respectively based on the exposure conditions that are currently used of CR and DR radiography devices. The acquired image has been assessed by 20 medical image professors using the assessment method of the Japanese Society for Tuberculosis Prevent. As a result, in the case of the CR system, the better image quality was obtained in the condition of 120 kVp and 1.5 mAs~2.4 mAs (quality score 91~95.5 points) than standard exposure condition(110 kVp, 3.2 mAs, 86 points). And exposure dose was evaluated as low with $61.3{\sim}98.4{\mu}Gy$ than standard condition($105.11{\mu}Gy$). In DR system, however, the image quality score was higher as 97~98.6 points in the lower tube voltage range (112 kVp, 2.4~3.2 mAs) condition than the standard exposure condition (125 kVp, 3.2 mAs, 91 points). In addition, the exposure dose was $61.5-77.2{\mu}Gy$ lower than standard condition($93{\mu}Gy$). In addition, the exposure dose was low as $61.5-77.2{\mu}Gy$ than standard condition($93{\mu}Gy$). With the results of this study, we confirmed that it is possible to reduce the patient exposure dose with the same image quality by adjusting the optimal exposure condition of digital device.

• The Journal of the Acoustical Society of Korea
• /
• v.41 no.5
• /
• pp.507-517
• /
• 2022

The PhotoAcoustic Microscopy (PAM) has been proved to be a useful tool for biological and medical applications due to its high spatial and contrast resolution. PAM is based on transmission of laser pulses and reception of PA signals. Since the strength of PA signals is generally low, not only are high-performance optical and acoustic modules required, but high-performance electronics for imaging are also particularly needed for high-quality PAM imaging. Most PAM systems are implemented with a combination of several pieces of equipment commercially available to receive, amplify, enhance, and digitize PA signals. To this end, PAM systems are inevitably bulky and not optimal because general purpose equipment is used. This paper reports a PA signal receiving system recently developed to attain the capability of improved Signal to Noise Ratio (SNR) and Contrast to Noise Ratio (CNR) of PAM images; the main module of this system is a low noise, wideband signal receiver that consists of two low-noise amplifiers, two variable gain amplifiers, analog filters, an Analog to Digital Converter (ADC), and control logic. From phantom imaging experiments, it was found that the developed system can improve SNR by 6.7 dB and CNR by 3 dB, compared to a combination of several pieces of commercially available equipment.