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The Long-Term Outcome and Rehabilitative Approach of Intraventricular Hemorrhage at Preterm Birth
Juntaek Hong,Dong-wook Rha 대한신경외과학회 2023 Journal of Korean neurosurgical society Vol.66 No.3
Technological advances in neonatology led to the improvement of the survival rate in preterm babies with very low birth weights. However, intraventricular hemorrhage (IVH) has been one of the major complications of prematurity. IVH is relevant to neurodevelopmental disorders, such as cerebral palsy, language and cognitive impairments, and neurosensory and psychiatric problems, especially when combined with brain parenchymal injuries. Additionally, severe IVH requiring shunt insertion is associated with a higher risk of adverse neurodevelopmental outcomes. Multidisciplinary and longitudinal rehabilitation should be provided for these children based on the patients’ life cycles. During the infantile period, it is essential to detect high-risk infants based on neuromotor examinations and provide early intervention as soon as possible. As babies grow up, close monitoring of language and cognitive development is needed. Moreover, providing continuous rehabilitation with task-specific and intensive repetitive training could improve functional outcomes in children with mild-to-moderate disabilities. After school age, maintaining the level of physical activity and managing complications are also needed.
A W-Band High-Efficiency CMOS Differential Current-Reused Frequency Doubler
Juntaek Oh,Jingyu Jang,Choul-Young Kim,Songcheol Hong THE INSTITUTE OF ELECTRICAL ENGINEERS 2015 IEEE Microwave and Wireless Components Letters Vol. No.
<P>A W-band differential frequency doubler using a current-reuse configuration in a 65 nm CMOS process is presented in this letter. The differential current-reuse circuit with a second harmonic coupling transformer is introduced to improve conversion gain at small input powers minimizing the effect of the RF bypass capacitor. The proposed circuit achieves a conversion gain of 0.8 ~ -4.2 dB and a fundamental rejection above 19 dB in the input frequency range of 36.5~44 GHz with -4 dBm input power. It has conversion gain variation below 1 dB when the input power varies from -7.4 to 0.1 dBm at 77 GHz. The dc power consumption is 14 mW. It has the highest conversion gain with the smallest chip size of 0.22 mm<SUP>2</SUP> among all V-/W-band CMOS frequency doublers.</P>
5-㎒ Pseudo-differential Current-mode CMOS Relaxation VCO with Temperature Stability of 41.8 ppm/℃
Juntaek Oh,Jong-Ryul Yang 대한전자공학회 2019 Journal of semiconductor technology and science Vol.19 No.6
This letter presents a pseudo-differential current-mode relaxation voltage-controlled oscillator for small form factor applications. A pseudodifferential current-mode comparator with a temperature compensated RC circuit was composed both to obtain half duty cycle and have a constant charge and discharge time with temperature change. A current source with two types of gate-oxide transistor combinations was able to obtain the reference voltage and had an ultra-low temperature coefficient, thus mitigating frequency variation with regard to temperature. The proposed voltage-controlled oscillator was implemented in a low power 65-㎚ CMOS process and occupied 0.011 ㎟. Measurements showed that the voltage-controlled oscillator operated at 4.75-5.09 ㎒ with a supply voltage of 1.0 V, and its DC power consumption was 40 ㎼ including a 3-stage buffer. A low frequency variation of 41.8 ppm/℃ was achieved for the temperature range of 20 to 100 ℃.
Highly efficient W-band 2.5 GHz bandwidth pulse generator with −1 dBm output power in 65 nm CMOS
Juntaek Oh,Jingyu Jang,Songcheol Hong IET 2016 Electronics letters Vol.52 No.3
<P>A W-band 2.5 GHz bandwidth pulse generator comprising a voltage-controlled oscillator (VCO) and a novel pulse former in a 65 nm CMOS technology is presented. The proposed sub-harmonic pumped pulse former, which plays roles as both a frequency doubler and a pulse former, is designed to obtain high efficiency using a transformer-based current reuse circuit. The VCO is implemented with a parallel combining transformer, which makes it insensitive to load variations due to pulse formation. Measurements show that the pulse generator achieves -1 dBm peak output power at 79 GHz. It can generate 800 ps pulse signals with an RF carrier of 76.1-79.6 GHz, achieving the energy cost rate of 50 pJ/pulse with a 1.25 GHz pulse repetition period.</P>
Projection-based Occupancy Map Coding for 3D Point Cloud Compression
Juntaek Park,Jongseok Lee,Seanae Park,Donggyu Sim 대한전자공학회 2020 IEIE Transactions on Smart Processing & Computing Vol.9 No.4
An occupancy map coding method to compress 3D point cloud data is proposed. A 3D point cloud can be coded by projecting into a texture, depth, and occupancy map. This paper presents an efficient way to signal consecutive fully occupied occupancy coding units with a single bit for each coding unit row of an object in the occupancy map is presented. The results showed that the proposed algorithm could save 3.02% of bits without coding loss compared to an existing algorithm.
Structural Basis for Bacterial Quorum Sensing-mediated Oxalogenesis
Oh, Juntaek,Goo, Eunhye,Hwang, Ingyu,Rhee, Sangkee American Society for Biochemistry and Molecular Bi 2014 The Journal of biological chemistry Vol.289 No.16
<P>The <I>Burkholderia</I> species utilize acetyl-CoA and oxaloacetate, substrates for citrate synthase in the TCA cycle, to produce oxalic acid in response to bacterial cell to cell communication, called quorum sensing. Quorum sensing-mediated oxalogenesis via a sequential reaction by ObcA and ObcB counteracts the population-collapsing alkaline pH of the stationary growth phase. Thus, the oxalic acid produced plays an essential role as an excreted public good for survival of the group. Here, we report structural and functional analyses of ObcA, revealing mechanistic features distinct from those of citrate synthase. ObcA exhibits a unique fold, in which a (β/α)<SUB>8</SUB>-barrel fold is located in the C-domain with the N-domain inserted into a loop following α1 in the barrel fold. Structural analyses of the complexes with oxaloacetate and with a bisubstrate adduct indicate that each of the oxaloacetate and acetyl-CoA substrates is bound to an independent site near the metal coordination shell in the barrel fold. In catalysis, oxaloacetate serves as a nucleophile by forming an enolate intermediate mediated by Tyr<SUP>322</SUP> as a general base, which then attacks the thioester carbonyl carbon of acetyl-CoA to yield a tetrahedral adduct between the two substrates. Therefore, ObcA catalyzes its reaction by combining the enolase and acetyltransferase superfamilies, but the presence of the metal coordination shell and the absence of general acid(s) produces an unusual tetrahedral CoA adduct as a stable product. These results provide the structural basis for understanding the first step in oxalogenesis and constitute an example of the functional diversity of an enzyme for survival and adaptation in the environment.</P>
Diatom Allantoin Synthase Provides Structural Insights into Natural Fusion Protein Therapeutics
Oh, Juntaek,Liuzzi, Anastasia,Ronda, Luca,Marchetti, Marialaura,Corsini, Romina,Folli, Claudia,Bettati, Stefano,Rhee, Sangkee,Percudani, Riccardo American Chemical Society 2018 ACS CHEMICAL BIOLOGY Vol.13 No.8
<P>Humans have lost the ability to convert urate into the more soluble allantoin with the evolutionary inactivation of three enzymes of the uricolytic pathway. Restoration of this function through enzyme replacement therapy can treat severe hyperuricemia and Lesch-Nyhan disease. Through a genomic exploration of natural gene fusions, we found that plants and diatoms independently evolved a fusion protein (allantoin synthase) complementing two human pseudogenes. The 1.85-Å-resolution crystal structure of allantoin synthase from the diatom <I>Phaeodactylum tricornutum</I> provides a rationale for the domain combinations observed in the metabolic pathway, suggesting that quaternary structure is key to the evolutionary success of protein domain fusions. Polyethylene glycol (PEG) conjugation experiments indicate that a PEG-modified form of the natural fusion protein provides advantages over separate enzymes in terms of activity maintenance and manufacturing of the bioconjugate. These results suggest that the combination of different activities in a single molecular unit can simplify the production and chemical modification of recombinant proteins for multifunctional enzyme therapy.</P> [FIG OMISSION]</BR>