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Pneumothorax in Full-term Neonates Transferred due to Respiratory Distress
( Younghyun Kim ),( Eunsil Lee ) 대한주산의학회 2019 Perinatology Vol.30 No.3
Objective: To investigate the incidence and course of pneumothorax in full-term infants with dyspnea. Methods: We retrospectively reviewed 607 newborn infants who had dyspnea and transferred to the tertiary medical center within 24 hours after birth, from 2011 to 2017. Results: Among the total 607 patients, 74 were excluded. Of the 533 patients, 72 (13.5%) diagnosed pneumothorax by first chest X-ray were in the pneumothorax group and 461 (86.5%) were in the control group. The incidence of pneumothorax was 13.5% (72/533) and 7.1% (35/496) in infants with pulmonary disease. The incidence of pneumothorax according to the underlying pulmonary disease was highest in congenital pneumonia (15.8%). The length of hospitalization was longer in the pneumothorax group. Of the pneumothorax, 28 (38.9%) were in the chest tube group and 44 (61.1%) were in the no chest tube group. The proportion of infants treated with mechanical ventilation was higher in the chest tube group. The time from birth to diagnosis, hospitalization days and duration of improvement of pneumothorax in chest X-ray were longer in the chest tube group than in the no chest tube group. Conclusion: The incidence of pneumothorax was quite common among the full-term infants who were transferred due to dyspnea, there was no significant difference between the two groups except for the longer hospitalization days for pneumothorax group. Considering the length of hospitalization and the need for chest tube insertion, the possibility of pneumothorax should be considered in full-term infants with dyspnea at primary medical institution.
System-Level Online Power Estimation Using an On-Chip Bus Performance Monitoring Unit
Younghyun Kim,Sangyoung Park,Youngjin Cho,Naehyuck Chang IEEE 2011 IEEE transactions on computer-aided design of inte Vol.30 No.11
<P>Quality power estimation is a basis of efficient power management of electronic systems. Indirect power measurement, such as power estimation using a CPU performance monitoring unit (PMU), is widely used for its low cost and area overheads. However, the existing CPU PMUs only monitor the core and cache activities, which result in a significant accuracy limitation in the system-wide power estimation including off-chip memory devices. In this paper, we propose an on-chip bus (OCB) PMU that directly captures on-chip and off-chip component activities by snooping the OCB. The OCB PMU stores the activity information in separate counters, and online software converts counter values into actual power values with simple first-order linear power models. We also introduce an optimization algorithm that minimizes the energy model to reduce the number of counters in the OCB PMU. We compare the accuracy of the power estimation using the proposed OCB PMU with real hardware measurement and cycle-accurate system-level power estimation, and demonstrate high estimation accuracy compared with CPU PMU-based estimation method.</P>
Transmit Power Optimization for Cooperative Beamforming in Uplink MIMO Ad-hoc Networks
Younghyun Jeon,Seungjoo Maeng 대한전자공학회 2017 대한전자공학회 학술대회 Vol.2017 No.1
In Ad-hoc networks, one great interest is its combination with multiple-input multiple-output (MIMO) transmission techniques. On this work, we consider a specific type of Ad-hoc networks called reverse-link MIMO Ad-hoc network (RMAN) and maximize the data rate with a power consumption constraint using cooperative beamforming techniques. Based on mathematical analysis, we design an algorithm which constructs optimal orthogonal weight vectors according to channel feedback and controls the transmission power according to a QoS-pricing value level. In simulation results, we show the validity of the analysis and the data rate performance of our proposed algorithm. We also show that the data rate of each link converges to a stationary point.
Vehicular Passenger Mobility-Aware Bandwidth Allocation in Mobile Hotspots
Younghyun Kim,Haneul Ko,Sangheon Pack,Shen, Xuemin Sherman IEEE 2014 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.13 No.6
<P>In this paper, we propose a vehicular passenger mobility-aware bandwidth allocation (V-MBA) scheme in mobile hotspots. The V-MBA scheme consists of both call admission control and bandwidth adjustment functions to lower handoff vehicle service dropping probability and efficiently utilize resource of base station. Specifically, a handoff priority scheme with guard bandwidth is employed to protect handoff vehicle service. Also, bandwidth is dynamically assigned to each vehicle by exploiting vehicular passenger movement pattern that includes getting on and off events at a station. We evaluate the V-MBA scheme by developing a continuous-time Markov chain model. Simulation results demonstrate that the V-MBA scheme can guarantee low new vehicle service blocking probability and handoff vehicle service dropping probability through flexible bandwidth allocation.</P>
Younghyun Yoon,Danbi Choi,Jeongjin Roh IEEE 2015 IEEE journal of solid-state circuits Vol.50 No.10
<P>This paper presents a delta-sigma modulator operating at a supply voltage of 0.4 V. The designed delta-sigma modulator uses a proposed hybrid switching integrator and operates at a low supply voltage without clock boosting or bootstrapped switches. The proposed integrator consists of both switched-resistor and switched-capacitor operations and significantly reduces distortion at a low supply voltage. Variation in the turn-on resistance, which is the main source of distortion, is avoided by placing the switches at the virtual ground node of the amplifier. The proposed low-voltage design scheme can replace commonly-used clock boosting techniques, which rely on internal high-voltage generation circuits. A fabricated modulator achieves a 76.1 dB signal-to-noise-plus-distortion ratio (SNDR) and an 82 dB dynamic range at a 20 kHz bandwidth. The measured total power consumption is 63 mu W from a 0.4 V supply voltage. The measured results show robust SNDR performance, even at +/- 10% supply voltage variations. The measured results also show stable performance over a wide temperature range.</P>