• KEPCO Journal on Electric Power and Energy
• /
• v.2 no.3
• /
• pp.391-395
• /
• 2016

In the last few decades, global electricity consumption has dramatically increased and has become drastically fluctuating and uncertain causing blackout. Due to the unexpected peak electricity demand, we need significant electricity supply. The solutions to these problems are smart grid system which is envisioned as future power system. Smart grid system can reduce electricity peak demand and induce effective electricity consumption through various price policies, demand response (DR) control methodologies, and state-of-the-art smart equipments in order to optimize electricity resource usage in an intelligent fashion. Demand response (DR) is one of the key technologies to enable smart grid. In this paper, we propose greedy technique for demand response smart grid system. The proposed scheme focuses on minimizing electricity bills, preventing system blackout and sacrificing user convenience.

• Smart Media Journal
• /
• v.13 no.1
• /
• pp.18-23
• /
• 2024

Power efficiency management in smart farms is important due to its link to climate change. As climate change negatively impacts agriculture, future agriculture is expected to utilize smart farms to minimize climate impacts, but smart farms' power consumption may exacerbate the climate crisis due to the current electricity production system. Therefore, it is essential to efficiently manage and optimize the power usage of smart farms. In this study, we propose a system that monitors the power usage of smart farm equipment in real time and predicts the power usage one hour later using GRU. CT sensors are installed to collect power usage data, which are analyzed to detect and prevent abnormal patterns, and combined with IoT technology to efficiently manage and monitor the overall power usage. This helps to optimize power usage, improve energy efficiency, and reduce carbon emissions. The system is expected to improve not only the energy management of smart farms, but also the overall efficiency of energy use.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.4
• /
• pp.511-519
• /
• 2013

Switching controllers for active magnetic bearings are claimed to minimize the copper losses because they do not use bias currents. In this study, we compare the performances of the switching controller with those of the widely used proportional-derivative (PD) controller. The PD controller is combined with a synchronous notch filter to reduce the effect of the unbalance disturbance. For a fair and objective comparison, the PD controller is designed systematically. The switching controller is designed so that the dynamics of the two controllers are almost identical. A system model is developed. This model includes the flexible modes of the rotor and the dynamics of the sensors and amplifiers. The simulation results show that the switching controller indeed reduces the copper loss at lower speeds. However, it fails to operate around the speed close to the bending mode of the rotor.

• Journal of the Korean Magnetics Society
• /
• v.20 no.6
• /
• pp.234-238
• /
• 2010

Solenoid diaphragm fuel pump, which to replace mechanical fuel pump system by utilizing cam-shaft driving force, is in the spotlight for being a high efficient green car component. However, there is a drawback in power consumption as a solenoid diaphragm fuel pump only relies on solenoid for its flux needed in reciprocating motion. Therefore, this research proposes permanent magnet type VCM (Voice Coil Motor) fuel pump system to minimized power consumption. Furthermore, the study compares and analyzes power consumption and dynamic performance between the current and the former solenoid diaphragm pump by conducting finite element analysis with the commercial electromagnetic solver, MAXWELL.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.16 no.3
• /
• pp.477-484
• /
• 2021

The 4kW class inverter for portable ESS designed through this study achieves lightweight and high power density by reducing the volume of passive devices (capacitors, inductors, etc.) suitable for portable use, and minimizes heat loss of the MOSFET through the low on resistance of the MOSFET. So that high efficiency can be achieved. In addition, in order to deliver high quality energy, it is designed to have a low THDV in accordance with the current KEPCO business handling guidelines, and is designed to output a sine wave with low distortion.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.8 no.1
• /
• pp.99-104
• /
• 2013

As a demand for the portable device requiring smaller size and better performance is in hike, reducing the size of conventionally used planar 2 dimensional integration circuit(IC) cannot be a solution for the enhancement of the semiconductor integration circuit technology due to an increase in RC delay among interconnects. To address this problem, a new technology of 3 dimensional integration circuit (3D-IC) has been developing. In this study, three-dimensional integrated device was investigated due to improve of reducing the size, interconnection problem, high system performance and functionality.

• Proceedings of the Korean Information Science Society Conference
• /
• 2007.10d
• /
• pp.176-179
• /
• 2007

센서 네트워크는 제한된 에너지를 가지는 작은 노드들로 구성이 된다. 제한된 자원을 가지는 센서 네트워크에서 저 전력에 대한 연구는 핵심 분야로써, 다양한 연구가 진행 중이다. 센서 네트워크에서 에너지 효율을 높이는 방법들이 많이 연구되고 있다. 센서 네트워크에서 가장 큰 에너지 손실을 가져오는 부분은 통신 부분이며, 질의 기반 센서 네트워크에서는 질의를 배포하게 될 때 에너지 소비의 주요 요소들이 발생하게 된다. 따라서, 본 논문은 베이스스테이션으로 다중 질의를 요청할 때 질의 합성을 통해 전달되는 질의 수를 최소화하여 질의의 배포에 따른 에너지 소비 요소를 줄이는데 그 목적이 있다. 질의는 조건절에서 특정 속성에 대해서 판별하는데, 본 논문에서 제안하는 방법은 속성에 따라 질의를 합성하여 원본 질의의 개수보다 적게 하는 것이다. 제안 알고리즘을 통해 합성된 질의가 센서 노드에게 전해지는 과정에서 데이터의 송수신 횟수 및 overhead를 줄일 수 있으며, 또한 센서 노드는 합성된 질의로 센싱 횟수를 줄 일 수 있어 에너지 효율을 높일 수 있다. 본 논문에서 제안한 방법과 일반적인 방법을 비교하기 위해 에너지 소모 절감 예를 살펴봤다.

• Journal of the Korean Magnetics Society
• /
• v.8 no.5
• /
• pp.308-316
• /
• 1998

In this paper, the effects of lateral displacement on the thrust, lift force and (guide force) are investigated by 3-D Finite Element Analysis (FEA) in controlled-PM LSM which has some strong points that electrical power can be minimized and the thrust and lift force can be simultaneously obtained. The variations of airgap flux density and the forces concerning lateral displacement have been analyzed and the effect of lateral displacement and airgap length on the motor performance have been investigated in detail by analysis and experiment results. As the result of this study, the characteristics of PM-LSM concerning with the change of lateral placement and airgap have been made clear quantitatively.

• Journal of KIISE:Computer Systems and Theory
• /
• v.36 no.5
• /
• pp.422-428
• /
• 2009

NAND flash memory is widely used in embedded systems because of many attractive features, such as small size, light weight, low power consumption and fast access speed. However, it requires garbage collection, which includes erase operations. Erase operation is slower than other operations. Further, a block has a limited erase lifetime (typically 100,000) after which a block becomes unusable. The proposed garbage collection policy focuses on minimizing the total number of erase operations, the deviation value of each block and the garbage collection time. NAND flash memory consists of pages of three types, such as valid pages, invalid pages and free pages. In order to achieve above goals, we use a page ratio to decide when to do garbage collection and to select the target victimblock. Additionally, we implement allocating method and group management method. Simulation results show that the proposed policy performs better than Greedy or CAT with the maximum rate 85% of reduction in the deviation value of the erase operations and 6% reduction in garbage collection time.

• Journal of KIISE:Computing Practices and Letters
• /
• v.15 no.9
• /
• pp.617-625
• /
• 2009

NAND flash memory is widely used in embedded systems because of many attractive features, such as small size, light weight, low power consumption and fast access speed. However, it requires garbage collection, which includes erase operations. Erase operation is very slow. Besides, the number of the erase operations allowed to be carried out for each block is limited. The proposed garbage collection method focuses on minimizing the total number of erase operations, the deviation value of each block and the garbage collection time. NAND flash memory consists of pages of three types, such as valid pages, invalid pages and free pages. In order to achieve above goals, we use a page rate to decide when to do garbage collection and to select the target victim block. Additionally, We implement allocating method and group management method. Simulation results show that the proposed policy performs better than Greedy or CAT with the maximum rate at 82% of reduction in the deviation value of erase operation and 75% reduction in garbage collection time.