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Less is more: need to simplify ETSI distributed congestion control algorithm
Seungnam Yang,Hyogon Kim,Seungho Kuk IET 2014 Electronics letters Vol.50 No.4
<P>In the European Telecommunication Standards Institute (ETSI) framework, the vehicle-to-vehicle (V2V) and the vehicle-to-roadside (V2R) communications on the 5 GHz frequency band must use the decentralised congestion control (DCC) algorithm standardised by the ETSI. The DCC algorithm distinguishes itself from other methods in that it simultaneously regulates no less than four parameters that all work to the identical effects. However, it is have claimed that this apparently reassuring feature is actually excessive and can lead DCC to perform sub-optimally. It is shown that it could be simplified to use fewer parameters by demonstrating that a physical layer data rate control, which is only one of the four used by the DCC, achieves a better result.</P>
A Self-Biased Current-Mode Amplifier With an Application to 10-bit Pipeline ADC
Seungnam Choi,Yunjae Suh,Joohyun Lee,Jinkyu Kim,Byungsub Kim,Hong-June Park,Jae-Yoon Sim IEEE 2017 IEEE Transactions on Circuits and Systems I: Regul Vol.64 No.7
<P>This paper presents a self-biased current-mode amplifier (CMAMP) suitable for a switched-capacitor circuit. The CMAMP uses a subthreshold-biased transimpedance stage as a current-sensing load, and minimizes static power dissipation by passing bias current only at the input stage. The first-order system behavior with single dominant pole gives stable phase margin without complicated frequency compensation. Self-biasing circuits automatically generate bias voltages to sustain performance over a wide range of supply voltage. The designed CMAMP is verified in a 10-bit pipeline analog-to-digital converter (ADC) fabricated in a 65-nm CMOS process. The ADC achieves a figure of merit of 14.3 fJ/c-s with a supply voltage of 0.6 V at 2.5 MS/s.</P>
Seungnam Yu(유승남),Hyojik Lee(이효직) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11
This study attempts to introduce a research case involving the integration of discrete event simulation and a virtual reality (VR) environment for the teleoperation of batch-process-based electro-metallurgical treatment conducted in a hot cell facility. Through this approach, the considered process could be further improved by addressing the physical problems identified in a VR simulation operated with discrete event simulation simultaneously.
Seungnam Choi,Hyunwoo Son,Jongshin Shin,Sang-Hyun Lee,Byungsub Kim,Hong-June Park,Jae-Yoon Sim IEEE 2016 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS PART 1 R Vol.63 No.2
<P>This paper presents a continuous-rate reference-less clock and data recovery (CDR) circuit with an asynchronous baud-rate sampling to achieve an adaptive equalization as well as a data rate acquisition. The proposed scheme also enables the use of a successive approximation register (SAR) based approach in the frequency acquisition and results in a fast coarse lock process. The CDR guarantees a robust operation of a fine locking even in the presence of large input data jitter due to the adaptive equalization and a jitter-tolerable rotation frequency detector (RFD) that eliminates a dead-zone problemwith a simple circuitry. The fabricated CDR in 65 nm CMOS shows a wide lock range of 0.65-to-10.5 Gb/s at a bit error rate (BER) of 10(-12). The CDR consumes 26 mW from a single supply voltage of 1 V at 10 Gb/s including the power consumption for equalizer. By an adaptive current bias control, the power consumption is also linearly scaled down with the data rate, exhibiting a slope of about 2 mW decrease per Gb/s.</P>
Seungnam Yu,Jonghui Han 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2
This paper describes the development and operation of an autonomous robotic system designed for pyroprocess automation. The unique challenges of pyroprocess automation, such as the need for a highly dry atmosphere to handle materials like chloride, are addressed through this system. For the experiments, a specialized dehumidifier and dry mock-up facility were designed to produce dry air condition. Performances of dry air conditioning for the various simulated situations were evaluated, including assessing worker access within a mock-up to determine the system’s feasibility. To enable automation, containers used for processing materials were modified to fit the gripper system of the gantry robot. The loading and unloading of materials in each equipment were automated to connect them with the robotic system. This gantry robot primarily utilized macro motions to approach waypoints containing process materials, reducing the need for precise approach motions. Its tapered jaw design allowed it to grip target objects even with imperfect positioning. The robot’s motions were programmed initially using a robot simulator for positioning and motion planning, and real-world accuracy was tested in a dry mock-up facility using the OPC platform. Finally, the paper discusses the potential application of XR (eXtended Reality) technology in this context, which could enhance the robot’s operation and provide valuable insights into the automation process. Further analysis of XR technology’s feasibility and benefits for this specific pyroprocess automation system are presented.
Seungnam Kim,Spyros A. Kinnas Techno-Press 2023 Ocean systems engineering Vol.13 No.2
This study investigates the influence of loading and inflow conditions on tidal turbine performance from a hydrodynamic and hydroacoustic point of view. A boundary element method is utilized for the former to investigate turbine performance at various loading conditions under zero/non-zero yaw inflow. The boundary element method is selected as it has been selected, tested, and validated to be computationally efficient and accurate for marine hydrodynamic problems. Once the hydrodynamic solutions are obtained, such as the time-dependent surface pressures and periodic motion of the turbine blade, they are taken as the known noise sources for the subsequence hydroacoustic analysis based on the Ffowcs Williams-Hawkings formulation given in a form proposed by Farassat. This formulation is coupled with the boundary element method to fully consider the three-dimensional shape of the turbine and the speed of sound in the acoustic analysis. For validations, a model turbine is taken from a reference paper, and the comparison between numerical predictions and experimental data reveals satisfactory agreement in hydrodynamic performance. Importantly, this study shows that the noise patterns and sound pressure levels at both the near- and far-field are affected by different loading conditions and sensitive to the inclination imposed in the incoming flow.