• Investigative Magnetic Resonance Imaging
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• v.19 no.4
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• pp.212-217
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• 2015

Purpose: For a single time-point hyperpolarized $^{13}C$ magnetic resonance spectroscopy imaging (MRSI) of animal models, scan-time window after injecting substrates is critical in terms of signal-to-noise ratio (SNR) of downstream metabolites. Pre-scans of time-resolved magnetic resonance spectroscopy (MRS) can be performed to determine the scan-time window. In this study, based on two-site exchange model, protocol-specific simulation approaches were developed for $^{13}C$ MRSI and the optimal scan-time window was determined to maximize the SNR of downstream metabolites. Materials and Methods: The arterial input function and conversion rate constant from injected substrates (pyruvate) to downstream metabolite (lactate) were precalibrated, based on pre-scans of time-resolved MRS. MRSI was simulated using two-site exchange model with considerations of scan parameters of MRSI. Optimal scan-time window for mapping lactate was chosen from simulated lactate intensity maps. The performance was validated by multiple in vivo experiments of BALB/C nude mice with MDA-MB-231 breast tumor cells. As a comparison, MRSI were performed with other scan-time windows simply chosen from the lactate signal intensities of pre-scan time-resolved MRS. Results: The optimal scan timing for our animal models was determined by simulation, and was found to be 15 s after injection of the pyruvate. Compared to the simple approach, we observed that the lactate peak signal to noise ratio (PSNR) was increased by 230%. Conclusion: Optimal scan timing to measure downstream metabolites using hyperpolarized $^{13}C$ MRSI can be determined by the proposed protocol-specific simulation approaches.

• The Korean Journal of Nuclear Medicine
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• v.22 no.1
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• pp.59-64
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• 1988

Because carcinoma of breast is known to readily metastasize to the bone, early detection of metastasis spread is very important. Two hundred thirty four consecutive patients who had $^{99m}Tc-MDP$ bone scans prior to treatment and during the follow up period were studied retrospectively to determine the contribution of the scans to staging, treatment and follow up examination between Jan. 1980 and Apr. 1987 in Seoul National University Hospital. 1) Positive bone scan rates in initial clinical stage I, II, III and IV were 0%, 4%, 14% and 53%, respectively. 2) The higher clinical stage is, the more cumulative risk of conversion to positive bone scan is during the same follow up period. 3) Conversion rate to positive bone scan in patients with lymph node metastasis is higher (50%) than those without metastasis (18%) (P < 0.001). We concluded that the bone scan in primary breast cancer was very useful to evaluate initial clinical stage and to perform the follow up examination.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.1
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• pp.49-56
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• 1994

This paper describes the design principles and methods of electronic processor for thermal imager with the SPRITE detector, operating in the 8-12 micron band. The thermal imager consists of a optical scanner containing the detector and an electrical signal processor. The optical scanner utilizing rotating polygon and oscillating mirror, is 2-dimensional serial/parallel scan type using 5 elements of the detector. And the electronic processor has pre-processing of 5 chnanel's thermal signal from the detector, and performs digital scan conversion to reform the parallel data stream into serial analog data compatible with conventional RS-170 video. Through the designed electronic processor, we have acquired a satisfactory thermal image. And the MRTD (Minimum Resolvable Temperature Difference) is 0.5$^{\circ}$K at 7.5 cycles/mm.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.130-133
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• 2003

Vertical Colour Selection (VCS) is an option for slim CRTs with increased sharpness and brightness. The direction of self-convergence of the DY is changed to vertical in order to obtain better spot uniformity, but the line scan direction remains horizontal. Hence, no video conversion is needed, contrary to transposed scan. In this paper we address two issues: First, there is a high risk of moire, since the scan lines and the phosphor stripes are parallel. We propose a feedback mechanism guiding the electron beams towards the middle of the mask slots. As positive side effects, the brightness is improved and the shadow mask can be made of a cheap type of steel. Secondly, VCS deflection coils have to satisfy different requirements than coils in ordinary CRTs. We discuss the design rules for self-convergent VCS coils and present simulation results.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.9-11
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• 1993

This paper decribed the development of Thermal Imaging Oservation System(TIOS) using the serial-parallel scan method. The detectors scan five lines at a time. These are put into serial order by electronic scan converter. Digital memory and high speed multiplexer are used for the serial conversion instead of charge coupled devices. As a result, thermal imaging system be presented with exellent performance which MRTD value is less than $0.5^{\circ}K$ at 7.5 cycles/mm.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.543-545
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• 1993

This paper decribed the development of Thermal Imaging Oservation System(TIOS) using the serial-parallel scan method. The detectors scan five lines at a tine. These are put into serial order by electronic scan converter. Digital memory and high speed multiplexer are used for the serial conversion instead of charge coupled devices. As a result, thermal imaging system be presented with exellent performance which MRTD value is less than $0.5^{\circ}K$ at 7.5 cycles/mm.

• Journal of Broadcast Engineering
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• v.11 no.3 s.32
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• pp.320-325
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• 2006

An image is partitioned into non-overlapping $8{\times}8$ blocks fer JPEG compression. A scan order converter is placed before the JPEG encoder to provide $8{\times}8$ blocks from the pixels in raster scan order. In general, its architecture requires two line memories for storing eight lines separately to allow the concurrent memory access by both the camera and JPEG processors. Although such architecture is simple to be implemented, it can be inefficient due to too excessive memory requirement as the image resolution increases. However, no deterministic addressing equation has been developed for scan conversion. In this paper, an effective memory addressing algorithm is proposed that can be devised only by adders and subtracters to implement a scan converter based on the single line memory.

• Journal of KIISE
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• v.44 no.5
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• pp.537-544
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• 2017

As a special form of the signed-digit representation, the NAF(non-adjacent form) minimizes the hamming weight by reducing the average density of the non-zero bits from the binary representation of the positive integer k. Due to this advantage, the NAF is used in various fields; in particular, it is actively used in cryptology. The existing NAF-conversion algorithm, however, is problematic because the conversion speed decreases when the LSB(least significant bit) frequently becomes "1" during the binary positive integer conversion process. This paper suggests a method for the improvement of the NAF-conversion speed for which the problems that occur in the existing NAF-conversion process are solved. To verify the performance improvement of the algorithm, the CPU cycle for the various inputs were measured on the ATmega128, a low-performance 8-bit microprocessor. The results of this study show that, compared with the existing algorithm, the suggested algorithm not only improved the processing speed of the major patterns by 20% or more on average, but it also reduced the NAF-conversion time by 13% or more.

• Journal of Radiation Protection and Research
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• v.46 no.3
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• pp.98-105
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• 2021

Background: In recent events of the coronavirus disease 2019 (COVID-19) pandemic, computed tomography (CT) scans are being globally used as a complement to the reverse-transcription polymerase chain reaction (RT-PCR) tests. It will be important to be aware of major organ dose levels, which are more relevant quantity to derive potential long-term adverse effect, for Korean pediatric and adult patients undergoing CT for COVID-19. Materials and Methods: We calculated organ dose conversion coefficients for Korean pediatric and adult CT patients directly from Korean pediatric and adult computational phantoms combined with Monte Carlo radiation transport techniques. We then estimated major organ doses delivered to the Korean child and adult patients undergoing CT for COVID-19 combining the dose conversion coefficients and the international survey data. We also compared our Korean dose conversion coefficients with those from Caucasian reference pediatric and adult phantoms. Results and Discussion: Based on the dose conversion coefficients we established in this study and the international survey data of COVID-19-related CT scans, we found that Korean 7-year-old child and adult males may receive about 4-32 mGy and 3-21 mGy of lung dose, respectively. We learned that the lung dose conversion coefficient for the Korean child phantom was up to 1.5-fold greater than that for the Korean adult phantom. We also found no substantial difference in dose conversion coefficients between Korean and Caucasian phantoms. Conclusion: We estimated radiation dose delivered to the Korean child and adult phantoms undergoing COVID-19-related CT examinations. The dose conversion coefficients derived for different CT scan types can be also used universally for other dosimetry studies concerning Korean CT scans. We also confirmed that the Caucasian-based CT organ dose calculation tools may be used for the Korean population with reasonable accuracy.

• Current Optics and Photonics
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• v.6 no.3
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• pp.304-312
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• 2022

Digital images of cultural relics captured using line scan cameras present limitations due to uneven intensity and low contrast. To address this issue, this report proposes a colour linear array image enhancement method that can maintain a constant colour. First, the colour linear array image is converted from the red-green-blue (RGB) colour space into the hue-saturation-intensity colour space, and the three components of hue, saturation, and intensity are separated. Subsequently, the hue and saturation components are held constant while the intensity component is processed using the established intensity compensation model to eliminate the uneven intensity of the image. On this basis, the contrast of the intensity component is enhanced using an improved local contrast enhancement method. Finally, the processed image is converted into the RGB colour space. The experimental results indicate that the proposed method can significantly improve the visual effect of colour linear array images. Moreover, the objective quality evaluation parameters are improved compared to those determined using existing methods.