• JSTS:Journal of Semiconductor Technology and Science
• /
• v.16 no.3
• /
• pp.300-311
• /
• 2016

The analog-to-digital-converter-based (ADC-based) backplane receivers that consist of a front-end ADC followed by a digital equalizer are gaining more popularity in recent years, as they support more sophisticated equalization required for high data rates, scale better with fabrication technology, and are more immune to PVT variations. Unfortunately, designing an ADC-based receiver that meets tight power and performance budgets of high-speed backplane link systems is non-trivial as both front-end ADC and digital equalizer can be power consuming and complex when running at high speed. This paper reviews the state of art designs for the front-end ADC and digital equalizers to suggest implementation choices that can achieve high speed while maintaining low power consumption and complexity. Design-space exploration using system-level models of the ADC-based receiver allows through analysis on the impact of design parameters, providing useful information in optimizing the power and performance of the receiver at the early stage of design. The system-level simulation results with newer device parameters reveal that, although the power consumption of the ADC-based receiver may not comparable to the receivers with analog equalizers yet, they will become more attractive as the fabrication technology continues to scale as power consumption of digital equalizer scales well with process.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.17 no.6
• /
• pp.1105-1112
• /
• 2022

Field data monitoring systems such as renewable energy generation and smart farm integrated control are developing from PC and server to mobile first, and various wireless communication and application services have emerged with the development of IoT technology. Low-power wide-area networks are services optimized for low-power, low-capacity, and low-speed data transmission, and data collected in the field is transmitted to designated storage servers or cloud-based data platforms, enabling data monitoring. In this paper, we implement an IoT repeater that collects field data with a single device and transmits it to a wireless carrier cloud data flat using a low-power wide-area network, and a monitoring app using it. Using this, the system configuration is simpler, the cost of deployment and operation is lower, and effective data accumulation is possible.

• Journal of the Korean Society of Safety
• /
• v.36 no.5
• /
• pp.71-78
• /
• 2021

There are regularly planned overhaul periods in thermal power plants, which involve the maintenance of the boiler of the power plants. However, thermal power plants workers are always exposed to risk during overhaul periods owing to the narrow space and significant dust inside the boiler. Therefore, it is essential to develop a safety monitoring system that is suitable for operating in this type of environment. In this study, we developed not only a worker three-dimensional (3D)-location monitoring system that can monitor and record the entry/exit of workers, their 3D-location, and fall accidents but also a method to secure the working environment and operation efficiency. This system comprises of a worker tag, which was equipped with an inertial measurement unit, a barometric pressure sensor, and a Bluetooth low energy (BLE), and the tags were given to each worker. In addition, the location of workers inside the boiler was measured using a pedestrian dead reckoning (PDR) method and BLE beacons. The location data of the workers tag were transmitted to the integrated database (DB) server through a gateway, and to the administrator monitoring system. The performance of the system was demonstrated inside an actual thermal power plant boiler, and the accuracy and reliability of the system were verified through a number of repeated tests. These results provide insights on designing a new system for monitoring enclosed spaces.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1330-1331
• /
• 2011

The on-grid distributed power system operated antiislanding due to the momently voltage sag of the power system, fault and etc. According to the 'Dispersed Generations in Distribution Systems Connection Technology Standard', the utilizable time ratio of PCS is low because of being put into in the steady state of the power system after 5 minutes. In this paper, the output characteristic is optimized with the hybrid system consisting of the wind system and PV system. And energy of hybrid system is supplied to the power system. Also, DVR function was applied to PCS to compensate the voltage sag frequently happening for a power system. The control performance of the proposed hybrid PCS is analyzed and simulated using PSIM to validate the system performace.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.3 no.2
• /
• pp.131-137
• /
• 1998

The solar cells should be operated at the maximum power point because its output characteristics are greatly fluctuated on the variation of insolation, temperature and load. Photovoltaic system needs an inverter which can interface the dc output power of solar cell with the residential ac load. The inverter has to supply a sinusoidal current and voltage to the load and the utility line with a high power factor. This paper proposes an utility interactive photovoltaic system designed with a step-up chopper and a PWM voltage source inverter. The step-up chopper operates in continuous mode by adjusting the duty ratio so that the photovoltaic system tracks the maximum power points of solar cell without any influence on the variation of insolation and temperature. The voltage source inverter operates in a manner that its output voltage is in phase with the utility voltage. The inverter supplies an ac power with high factor and low level of harmonics to the load and the utility power system.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.11 no.9
• /
• pp.398-405
• /
• 2001

The maximum and mean indicated pressure of two stroke low speed diesel engine has been continuously increased with a view of increasing engine power and also reducing fuel consumption. As a result, axial excitation has been increased comparing to that of the previous one. So the axial vibration damper in standard one is applied to all two stroke low speed diesel engine at the free end of crankshaft. Though many studies were carried out for marine use, few has been made for diesel power plant because there was little demand for power plant. Nowadays, diesel engine is much to be used for many benefits. In this paper, the optimum design of axial vibration on the 65 kW diesel power plant with tow 9K80MC-S engines of 9 cylinders was carried out. And the axial-torsional coupled vibration of this shafting system is identified by theoretical analysis and vibration measurement.

• New & Renewable Energy
• /
• v.20 no.1
• /
• pp.116-125
• /
• 2024

Ultra-low-head is an unexplored classification among the sites in which hydroelectric power can be produced. This is typically owing to the low power output and the economic value of the turbines available in this segment. A turbine capable of operating in an ultra-low-head condition without the need of a dam to produce electricity is developed in this study. A gate structure installed at a shallow water channel acting as a weir generates artificial head for the turbine mounted on the gate to produce power. The turbine and generator are designed to be compact and submersible for an efficient and silent operation. The gate angle is adjustable to operate the turbine at varying flow rates. The turbine is designed and tested using computational fluid dynamics tools prior to manufacturing and experimental studies. A parametric study of the runner blade parameters is conducted to obtain the most efficient blade design with minimal hydraulic losses. These parameters include the runner stagger and runner leading edge flow angles. The selected runner design showed improved hydraulic characteristics of the turbine to operate in an ultra-low-head site with minimal losses.

• Proceedings of the IEEK Conference
• /
• 2004.06b
• /
• pp.561-564
• /
• 2004

The motion estimation which requires huge computation consumes large power in a video encoder. Although a number of fast-search algorithms are proposed to reduce the power consumption, the smaller the computation, the worse the performance they have. In this paper, we propose an architecture that a low energy management scheme can be applied with several fast-search algorithm. In addition. we show that ECVH, a software scheduling scheme which dynamically changes the search algorithm, the operating frequency, and the supply voltage using the remaining slack time within given power-budget, can be applied to the architecture, and show that the power consumption can be reduced.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.10
• /
• pp.1790-1795
• /
• 2008

Energy scavenging is a technique that converts ambient energy, for example, vibration and light, to electrical energy in order to supply power to low power electronic devices such as ubiquitous sensors. In this paper, we propose an optimal operation condition of power delivery circuit and design strategy for energy scavenging system in which the generated power is order of microwatt and, consequently, efficient handling of power is critical. We also propose that high data transmission rate is more realistic optimal design objective rather than high energy efficiency. It is shown that disconnection of load from the storage capacitor right after data transmission reduces energy wasting and that optimal value of storage capacitor can be determined at this condition. The feasibility of our propose is proved by experiments and we believe that the proposed design strategy will promote the application of piezoelectric micropower generator to the ubiquitous sensor networks.

• Nuclear Engineering and Technology
• /
• v.34 no.5
• /
• pp.436-444
• /
• 2002

The robust controller for the nuclear reactor power control system is designed. Since the reactor model is not exact, it is necessary to design the robust controller that can work in the real situations of perturbations. The reactor model is described in the form of transfer function and the bound of each coefficient is determined to set up the linear interval system. By the Kharitonov and the edge theorem, a frequency based design template is made and applied to the determination of the controller. The controller designed by this method is simpler than that obtained by the H$_{\infty}$. Although the controller is designed with the basis of high power, it could be used even at low power.n at low power.