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Development of PET/MRI with insertable PET for simultaneous PET and MR imaging of human brain.
Jung, Jin Ho,Choi, Yong,Jung, Jiwoong,Kim, Sangsu,Lim, Hyun Keong,Im, Ki Chun,Oh, Chang Hyun,Park, Hyun-wook,Kim, Kyung Min,Kim, Jong Guk Published for the American Association of Physicis 2015 Medical physics Vol.42 No.5
<P>The purpose of this study was to develop a dual-modality positron emission tomography (PET)/magnetic resonance imaging (MRI) with insertable PET for simultaneous PET and MR imaging of the human brain.</P>
Low-noise fast-response readout circuit to improve coincidence time resolution
Jiwoong Jung,Yong Choi,Seunghun Back,Jin Ho Jung,Sangwon Lee,Yeonkyeong Kim Korean Nuclear Society 2024 Nuclear Engineering and Technology Vol.56 No.4
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.
An improved time over threshold method using bipolar signals
Jung, Jiwoong,Choi, Yong,Kim, Kyu bom,Lee, Sangwon,Choe, Hyeok-jun IOP 2018 Physics in medicine & biology Vol.63 No.13
<P>The time over threshold (TOT) method has been recently proposed as a signal processing method used to calculate time and energy information by measuring the pulse arrival time and pulse duration over a preset threshold. Although TOT has been reported as an effective method for front end readout in PET applications, it has several limitations, including its non-linearity, lower dynamic range, and a trade-off between energy resolution and coincidence resolving time (CRT). In this study, we propose a novel design we developed to improve performance with regard to these problems occurring in the conventional TOT by employing a bipolar signal and two comparators. Using a high frequency CR shaping filter, a detected signal was converted into a bipolar signal, and the positive pulse of the converted bipolar signal had a fast rising time, while the negative pulse had a linear slope. The bipolar TOT circuit was composed of a preamplifier, a CR shaping filter, and two comparators. The PET detector was composed of a single LYSO coupled with 4 × 4 SiPM arrays, a bipolar TOT circuit, and an FPGA based TDC. And this was constructed to evaluate the performance of the proposed bipolar TOT method. A 16-ch PET detector module consisting of a 4 × 4 array LYSO coupled to a 4 × 4 SiPM arrays, an Anger logic discretized positioning circuit, and a 4-ch bipolar TOT circuit was also constructed to evaluate the functionality of the bipolar TOT method for PET applications. The pulse height resolution and CRT were measured using both the bipolar TOT method and the conventional TOT method. While the bipolar TOT method provided a similar pulse height resolution (10.4% ± 0.1%), the integral non-linearity (1.4%) and CRT (168 ± 4 ps) measured using the bipolar TOT method were greatly improved compared to those (17.2% and 258 ± 15 ps, respectively) measured with the conventional TOT method. The positions of the crystals were clearly identified, as seen in the flood histogram acquired using the 4-ch bipolar TOT circuit. The measured average pulse height resolution and average CRT for the 16-ch detector module were 11.5% ± 0.2% and 516 ± 24 ps. The results obtained in this study indicate that the bipolar TOT method requiring a relatively small number of electronic components could effectively improve the CRT, linearity and dynamic range. Furthermore, they also demonstrated the extendibility allowing the development of a PET system that consists of a large number of detectors.</P>
Yoon Hee Choo,Moinay Kim,Jae Hyun Kim,Hanwool Jeon,Hee-Won Jung,Eun Jin Ha,Jiwoong Oh,Youngbo Shim,Seung Bin Kim,Han-Gil Jung,So Hee Park,Jung Ook Kim,Junhyung Kim,Hyeseon Kim,Seungjoo Lee 대한신경외과학회 2023 Journal of Korean neurosurgical society Vol.66 No.6
The brain houses vital hormonal regulatory structures such as the hypothalamus and pituitary gland, which may confer unique susceptibilities to critical illness-related corticosteroid insufficiency (CIRCI) in patients with neurological disorders. In addition, the frequent use of steroids for therapeutic purposes in various neurological conditions may lead to the development of steroid insufficiency. This abstract aims to highlight the significance of understanding these relationships in the context of patient care and management for physicians. Neurological disorders may predispose patients to CIRCI due to the role of the brain in hormonal regulation. Early recognition of CIRCI in the context of neurological diseases is essential to ensure prompt and appropriate intervention. Moreover, the frequent use of steroids for treating neurological conditions can contribute to the development of steroid insufficiency, further complicating the clinical picture. Physicians must be aware of these unique interactions and be prepared to evaluate and manage patients with CIRCI and steroid insufficiency in the context of neurological disorders. This includes timely diagnosis, appropriate steroid administration, and careful monitoring for potential adverse effects. A comprehensive understanding of the interplay between neurological disease, CIRCI, and steroid insufficiency is critical for optimizing patient care and outcomes in this complex patient population.
Jung, Junhee,Kim, Sunbo,Park, Jinjoo,Shin, Chonghoon,Pham, Duy Phong,Kim, Jiwoong,Chung, Sungyoun,Lee, Youngseok,Yi, Junsin American Scientific Publishers 2015 Journal of Nanoscience and Nanotechnology Vol.15 No.10
<P>This article mainly discusses the difference between p-i-n and n-i-p type solar cells. Their structural difference has an effect on cell performance, such as open circuit voltage and fill factor. Although the deposition conditions are the same for both p-i-n and n-i-p cases, the substrate layers for depositing p-type microcrystalline silicon layers differ. In n-i-p cells, the substrate layer is p-type amorphous silicon oxide layer; whereas, in p-i-n cells, the substrate layer is ZnO:Al. The interfacial change leads to a 12% difference in the crystallinity of the p-type microcrystalline silicon layers. When the p-type microcrystalline silicon layer's crystallinity was not sufficient to activate an internal electric field, the open, circuit voltage and fill factor decreased 0.075 V and 7.36%, respectively. We analyzed this problem by comparing the Raman spectra, electrical conductivity, activation energy and solar cell performance. By adjusting the thickness of the p-type microcrystalline silicon layer, we increased the open circuit voltage of the n-i-p cell from 0.835 to 0.91 V.</P>
Jung, Sungwon,Park, Sohyeon,Choi, Woojin,Heo, Jiwoong,Kwon, Jaesung,Choi, Sunghwan,Hong, Jinkee Elsevier 2020 Journal of industrial and engineering chemistry Vol.84 No.-
<P><B>Abstract</B></P> <P>Technologies that can overcome the poor mechanical properties of the coatings with bacterial anti-adhesion effect based on super-wetting properties are still challenging. In this study, we developed a durable superhydrophilic nanocomposite coatings composed of polysaccharide matrix and organosilicate (OS) compound filler. In brief, carboxymethylcellulose (CMC) and chitosan (CS)-based multilayer films were fabricated via Layer-by-layer (LbL) assembly then crosslinking for the films was performed to improve inner stability and induce superhydrophilicity. As second step, we synthesized a biocompatible and robust organosilicate compound via sol-gel reaction and incorporate it as reinforcing filler into the superhydrophilic films. Consequently, durable hybrid superhydrophilic nanocomposites were coated on the substrate, and various chemical analysis and performance evaluations of the coatings were performed. The mechanical properties of the composite coatings were significantly improved due to the OS acting as a reinforcing filler in the multilayer films. Furthermore, the coatings exhibited excellent biocompatibility and transparency and exerted antibacterial effect based on superhydrophilic property. This study presents a practical strategy to solve the poor durability, the limitation of super-wetting coatings widely applied in various fields.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Diesel-DME 혼합연료의 정적챔버내에서의 분무 및 단기통엔진내에서의 연소, 배기특성에 관한 연구
양지웅(jiwoong Yang),정재훈(jahoon Jung),윤상진(sangjin Yoon),임옥택(ocktaeck Lim) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
The purpose of this study was compared the spray characteristics, combustion characteristics and emissions(NOx, CO, HC, smoke) of a typical fuel(100% Diesel,DME) and Diesel-DME blended fuel in a Constant Volume Chamber(CVC) and a single-cylinder DI diesel engine. Spray characteristics were investigated about varied ambient pressure and fuel injection pressure using the common rail fuel injection system when the fuel mixture ratio is varied. the spray characteristic research parameters were spray shape, penetration length, and spray angle at seven hole injector. common types of injectors were used(Bosch). Two types of blended fuel by the mass fraction was used. The typical fuel(100% Diesel,DME) and The blended fuel by mixture ratio 95:5, 90:10 (Diesel:DME) were used. The Injection pressure was fixed by 70MPa when the ambient Pressure was varied 0,2.5 and 5MPa. The combustion experiments was conducted in single cylinder engine equipped with common rail. injection pressure is 700 bar at 1200 rpm. The amount of injected fuels is adjusted to obtain the fixed input calorie value as 972.2 J/cycle in order to compare with the fuel conditions.