• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1532-1537
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• 2024

Time-of-flight (TOF) PET detectors with fast-rise-time scintillators and fast-single photon time resolution silicon photomultiplier (SiPM) have been developed to improve the coincidence timing resolution (CTR) to sub-100 ps. The CTR can be further improved with an optimal bandwidth and minimized electronic noise in the readout circuit and this helps reduce the distortion of the fast signals generated from the TOF-PET detector. The purpose of this study was to develop an ultra-high frequency and fully-differential (UF-FD) readout circuit that minimizes distortion in the fast signals produced using TOF-PET detectors, and suppresses the impact of the electronic noise generated from the detector and front-end readout circuits. The proposed UF-FD readout circuit is composed of two differential amplifiers (time) and a current feedback operational amplifier (energy). The ultra-high frequency differential (7 GHz) amplifiers can reduce the common ground noise in the fully-differential mode and minimize the distortion in the fast signal. The CTR and energy resolution were measured to evaluate the performance of the UF-FD readout circuit. These results were compared with those obtained from a high-frequency and single ended readout circuit. The experiment results indicated that the UF-FD readout circuit proposed in this study could substantially improve the best achievable CTR of TOF-PET detectors.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.11
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• pp.2032-2038
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• 2007

Embedded Controller which controls whole system is most important part of embedded system. Nowadays, new technique called SoC is more using than ASIC. But SoC have some problems. Because of long development time and high cost, it is hard to applying SoC to small and medium enterprise. So many companies use IP technique combined with embedded processor. High resolution inkjet marking system is printing system with embedded controller. It is used in various part of industry. But it has many problems such as printing quality, marking errors, system faults and so on. In this paper, we designed and implemented IP that can solve the printing quality problems. We analyzed total-logic-elements and timing by simulation. As a result of simulation, we could verified that output signals satisfied reference timing. Appling IP to high resolution inkjet marking system, we could get good quality printing message.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.1
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• pp.7-13
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• 2020

As a countermeasure against the threat of jamming which can disrupt operation of the Global Positioning System (GPS) receivers, various kinds of technique to estimate the Direction-Of-Arrivals (DOAs) of incoming jamming signals have been widely studied, and among them, the MUltiple SIgnal Classification (MUSIC) algorithm is known to provide very high resolution. However, since the previous studies regarding the MUSIC algorithm does not consider the orientation of each antenna element of antenna arrays, there is a possibility that DOA estimation performance degrades in the case of a misaligned antenna array whose antenna elements are not oriented along the same direction. As an effort to solve this problem, there exists a previous work which presents an MUSIC-based method for DOA estimation. However, the error between the real and measured values of each antenna orientation is not taken into consideration. Therefore, in this paper, the effect of the aforementioned error on the DOA estimation performance in the case of a misaligned antenna array is analyzed by simulations.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.2
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• pp.91-98
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• 2022

In the next generation wireless communication system, the beamforming technique based on a massive antenna is one of core technologies for transmitting and receiving huge amounts of data, efficiently and accurately. For highly performed and highly reliable beamforming, it is required to accurately estimate the Angle of Arrival (AOA) for the desired signal incident to an antenna. Employing the massive antenna with a large number of elements, although the accuracy of the AOA estimation is enhanced, its computational complexity is dramatically increased so much that real-time communication is difficult. In order to improve this problem, AOA estimation algorithms based on the massive antenna with the low computational complexity have been actively studied. In this paper, we compute and analyze the computational complexity of the cascade AOA estimation algorithm based on the Flexible Massive Concentric Circular Array (FMCCA). In addition, its computational complexity is compared to conventional AOA estimation techniques such as the Multiple Signal Classification (MUSIC) algorithm with the high resolution and the Only Beamspace MUSIC (OBM) algorithm.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1247-1249
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• 2009

We have successfully developed the 22 inch WSXGA+ DLS(Data Line Sharing) Panel driving in 75 Hz. In the large size and high resolution panels, it is very difficult to design the DLS Panels without failure because of the very short charging time and the large signal delay. So, we first investigated the charging order to find the most adequate charging type to the large size and high resolution panels. And then, we optimized the design of DLS in terms of improving the charging properties using the technologies of the Delta-doping TFTs, Cu metal electrodes and optimization of panel design value and the circuit signal timing.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.3
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• pp.51-61
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• 2020

Drought events are not clear when those start and end compared with other natural disasters. Because drought events have different timing and severity of damage depending on the region, various studies are being conducted using satellite images to identify regional drought occurrence differences. In this study, we investigated the applicability of drought assessment using the Evaporative Stress Index (ESI) based on Moderate Resolution Imaging Spectroradiometer (MODIS) satellite images. The ESI is an indicator of agricultural drought that describes anomalies in actual and reference evapotranspiration (ET) ratios that are retrieved using remotely sensed inputs of Land Surface Temperature (LST) and Leaf Area Index (LAI). However, these approaches have a limited spatial resolution when mapping detailed vegetation stress caused by drought, and drought hazard in the actual crop cultivation areas due to the small crop cultivation in South Korea. For these reasons, the development of a drought index that provides detailed higher resolution ESI, a 500 m resolution image is essential to improve the country's drought monitoring capabilities. The newly calculated ESI was verified through the existing 5 km resolution ESI and historical records for drought impacts. This study evaluates the performance of the recently developed 500 m resolution ESI for severe and extreme drought events that occurred in South Korea in 2001, 2009, 2014, and 2017. As a result, the two ES Is showed high correlation and tendency using Receiver Operating Characteristics (ROC) analysis. In addition, it will provide the necessary information on the spatial resolution to evaluate regional drought hazard assessment and and the small-scale cultivation area across South Korea.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.247-249
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• 1988

The most space-consuming element of digital image processing system is the video memory. Though this problem is solved by DRAMs, timing constraints posed by video data rates. The cycle time of DRAMs can be diminished by serial transferring and reading or writing pixel datas at the same time. This paper resents the design of 1024${\times}$512 video memory using this technique.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1053-1056
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• 2004

Chunghwa Picture Tubes, LTD. (CPT) has developed a Novel TFT-LCD Driving Techniquel. This new technique is developed in combination with other state-of-the-art image processing solutions such as image compression / decompression, motion detection, and noise reduction. By applying the Novel Driving Technique to the high resolution TFT-LCD, it was found that the response time can be effectively reduced with a lower overall system cost by smaller frame memory requirement, lower EMI by less memory band-width. Likewise, higher display quality can also be achieved in that the unexpected noises generated by over-drive can be eliminated. The Novel TFT-LCD Driving Technique has been successfully implemented to the 30 inch WXGA (1280${\times}$768) resolution TFT LCD commercial TV module. It was found that the quality of moving picture was better improved compared with that of the conventional fast response driving method.

• Journal of Medicine and Life Science
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• v.20 no.2
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• pp.73-82
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• 2023

Multiple studies have reported on unilateral axillary adenopathy following coronavirus disease 2019 (COVID-19) vaccination, which is currently recognized as a common finding. Here, we present a series of eight adult patients with reactive axillary lymphadenopathy following COVID-19 vaccination, in whom the follow-up ultrasonography (US) showed resolution of a previously noted unilateral axillary adenopathy. From March 2021 to March 2022, 2,599 consecutive women underwent breast US in Jeju National University Hospital. We identified 10 patients with unilateral axillary lymphadenopathy following COVID-19 vaccination detected on the breast US. The 10 patients were recommended for follow-up US. Two patients were lost to follow-up, whereas the remaining eight patients underwent follow-up US, in whom resolution of the unilateral axillary lymphadenopathy was noted. Radiologists should be aware of evolving guidelines for evaluating and managing axillary lymphadenopathy to avoid false positive biopsies. Recent studies on lymphadenopathy following COVID-19 vaccination show that a prolonged duration until resolution is often observed. Therefore, a follow-up US examination at least 12 weeks after vaccination may be reasonable. Furthermore, management guidelines should include a risk-stratified approach considering both vaccination timing and the patient's overall risk of metastatic disease.

• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3790-3797
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• 2021

Although the individual channel readout method can improve the performance of PET detectors with pixelated photo-sensors, such as silicon photomultiplier (SiPM), this method leads to a significant increase in the number of readout channels. In this study, we proposed a novel multiplexing method that could effectively reduce the number of readout channels to reduce system complexity and development cost. The proposed multiplexing circuit was designed to generate bipolar pulses with different zero-crossing points by adjusting the time constant of the high-pass filter connected to each channel of a pixelated photo-sensor. The channel position of the detected gamma-ray was identified by estimating the width between the rising edge and the zero-crossing point of the bipolar pulse. In order to evaluate the performance of the proposed multiplexing circuit, four detector blocks, each consisting of a 4 × 4 array of 3 mm × 3 mm × 20 mm LYSO and a 4 × 4 SiPM array, were constructed. The average energy resolution was 13.2 ± 1.1% for all 64 crystal pixels and each pixel position was accurately identified. A coincidence timing resolution was 580 ± 12 ps. The experimental results indicated that the novel multiplexing method proposed in this study is able to effectively reduce the number of readout channels while maintaining accurate position identification with good energy and timing performance. In addition, it could be useful for the development of PET systems consisting of a large number of pixelated detectors.