• 드라이브 ㆍ 컨트롤
• /
• 제17권2호
• /
• pp.38-44
• /
• 2020

Various efforts have been initiated to reduce the energy consumption of the compressor as it is one of the approaches to saving a large portion of the fixed cost of the production site. Various results of reducing the energy consumption of the compressor have been reported, but to reduce the energy consumption of the compressors fundamentally, regular management of the compressor should ensure optimum operation. This requires periodic on-site visits by experts, but is often overlooked as a cost issue, resulting in the use of the compressor in low-efficiency conditions. Thus, it is necessary to develop a low-cost evaluation technology for compressor condition monitoring and efficiency analysis to ensure that the compressor is always driven at the optimum efficiency without imposing undue burden on the compressor user. In this study, a sensor was installed at the inlet, outlet, and power supply of the compressor, and a method for evaluating the energy consumption of the compressor using the minimum sensor was derived. The experimental results are presented to show the validity of the proposed method. It was confirmed that the energy consumption of the compressor can be easily as well as efficiently evaluated by using the method developed in this study.

• Corrosion Science and Technology
• /
• 제12권5호
• /
• pp.227-232
• /
• 2013

A number of components installed in the secondary system of nuclear power plants are exposed to aging mechanisms such as FAC (Flow-Accelerated Corrosion), Cavitation, Flashing, and LDIE (Liquid Droplet Impingement Erosion). Those aging mechanisms can lead to thinning of the components. In April 2013, one (1) inch small bore piping branched from the main steam line experienced leakage resulting from wall thinning in a 1,000 MWe Korean PWR nuclear power plant. During the normal operation, extracted steam from the main steam line goes to condenser through the small bore piping. The leak occurred in the downstream of an orifice. A control valve with vertical flow path was placed on in front of the orifice. This paper deals with UT (Ultrasonic Test) thickness data, SEM images, and numerical simulation results in order to analyze the extent of damage and the cause of leakage in the small bore piping. As a result, it is concluded that the main cause of the small bore pipe wall thinning is liquid droplet impingement erosion. Moreover, it is observed that the leak occurred at the reattachment point of the vortex flow in the downstream side of the orifice.

• 전기학회논문지
• /
• 제58권5호
• /
• pp.936-943
• /
• 2009

Dynamic voltage restorer(DVR) is now more preferable enhancement than other power quality enhancement in industry to reduce the impact of voltage faults, especially voltage sags to sensitive loads. The main controllers for DVR consists of PLL(phase locked loop), compensation voltage calculator and voltage compensator. PLL detects the voltage faults and phase. Compensation voltage calculator calculates the reference voltage from the source voltage and phase. With calculated compensation voltage from PLL, voltage compensator restores the source voltage. If PLL detect ideal phase, compensation voltage calculator calculates ideal compensation voltage. Therefore, PLL for DVR is very important. This paper proposes the new method of PLL in DVR. First, the power circuit of DVR system is analyzed in order to compensate the voltage sags. Based on the analysis, new PLL for improving transient response of DVR is proposed. The proposed method uses band rejection filter(BRF) at q-axis in synchronous flame. In order to calculate compensation voltage in commercial instruments, the PQR theory is used. Proposed PLL method is demonstrated through simulation using Matlab-Simulink and experiment, and by checking load voltage, confirms operation of the DVR

• 한국생산제조학회지
• /
• 제21권5호
• /
• pp.778-783
• /
• 2012

Due to the increase of oil price, the needs of the reduction of the fuel cost is rising. Therefore, necessity of hybrid vehicle that runs with engine and the electric motor is on the rise. In order to improve the performance of hybrid vehicle, many researches is carried out. Hybrid vehicles have been developed with the various layout such as serial type, parallel type, power split type, and multi-mode type. The multi-mode hybrid vehicles are designed to show the efficient driving characteristics at low speed and high speed. But the multi-mode system have the problem such as frequent clutch engagement. Frequent clutch engagement causes the shock of vehicles, and the shock inhibits the ride comfort. In this study, automation mechanism of clutch operation is proposed to mitigate the shock at engaging clutch. For this purpose, the dynamic characteristics of motor control is numerically analyzed by using Matlab/Simulink.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
• /
• pp.855-858
• /
• 1998

Many semiconductive switches are operated in series for high voltage operation. The same number of gate drivers are needed to control all the switches, hence, the drivers cause high cost and system complexity. In this study, a simple and low cost gate driver for high voltage thyristor diode switches is investigated. This gate driver can operate several high voltage thyristor diode switches at the same time.

• 생물환경조절학회지
• /
• 제26권4호
• /
• pp.353-360
• /
• 2017

본 연구에서는 장미 재배온실을 대상으로 온실 내부의 태양잉여열과 외부의 공기열을 선택적 열원으로 이용하여 온실난방용 온수를 생산할 수 있는 공기 대 물 히트펌프의 설계와 성능시험을 수행하였다. 태양잉여열 이용 축열운전과 외기열 이용 축열운전은 작물의 생육적온을 고려한 온실내부의 설정온도에 따라 자동전환 되도록 설계하였다. 제어반에 12개의 기준온도를 설정함으로써 축열운전 전환, 난방, 환기를 자동제어하며, 태양잉여열-외기열 선택적 축열운전에서 축열조의 온도는 축열능력과 난방부하에 대응하여 $35{\sim}52^{\circ}C$로 3단계 변온제어 하였다. 태양잉여열-외기열 선택적 축열에서 태양잉여열 이용 축열은 전체 시간의 23.1%, 외기열 이용 축열은 30.7%, 히트펌프 휴지시간은 46.2%를 차지하였으며, 난방성능계수는 태양잉여열 이용 축열 시 3.83, 외기열 이용 축열시 2.77, 전체 3.24로 평가되었다. 비교시험을 위해 축열조 온도를 $50{\sim}52^{\circ}C$로 항온제어 하는 조건에서 외기열 단독 이용 축열 시험을 수행하였으며 이때의 난방성능계수는 2.33으로 분석되었다. 결과적으로 공기 대 물 히트 펌프의 열원으로 온실내부 태양잉여열과 외부 공기열을 병용하고, 축열조 온도를 변온제어 한 결과 일반적인 외기열 이용 축열운전과 축열조 항온제어에 비해 난방성능 계수가 39% 향상됨을 확인하였다.

• 세라미스트
• /
• 제21권2호
• /
• pp.4-18
• /
• 2018

Lastly, neuromorphic computing chip has been extensively studied as the technology that directly mimics efficient calculation algorithm of human brain, enabling a next-generation intelligent hardware system with high speed and low power consumption. Three-terminal based synaptic transistor has relatively low integration density compared to the two-terminal type memristor, while its power consumption can be realized as being so low and its spike plasticity from synapse can be reliably implemented. Also, the strong electrical interaction between two or more synaptic spikes offers the advantage of more precise control of synaptic weights. In this review paper, the results of synaptic transistor mimicking synaptic behavior of the brain are classified according to the channel material, in order of silicon, organic semiconductor, oxide semiconductor, 1D CNT(carbon nanotube) and 2D van der Waals atomic layer present. At the same time, key technologies related to dielectrics and electrolytes introduced to express hysteresis and plasticity are discussed. In addition, we compared the essential electrical characteristics (EPSC, IPSC, PPF, STM, LTM, and STDP) required to implement synaptic transistors in common and the power consumption required for unit synapse operation. Generally, synaptic devices should be integrated with other peripheral circuits such as neurons. Demonstration of this neuromorphic system level needs the linearity of synapse resistance change, the symmetry between potentiation and depression, and multi-level resistance states. Finally, in order to be used as a practical neuromorphic applications, the long-term stability and reliability of the synapse device have to be essentially secured through the retention and the endurance cycling test related to the long-term memory characteristics.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2007년도 추계학술대회 논문집
• /
• pp.313-318
• /
• 2007

Interior permanent magnet synchronous motor(IPMSM) has become a popular choice in electric vehicle applications, due to their excellent power to weight ratio. This paper proposes maximum torque control of IPMSM drive using adaptive fuzzy neural network controller and artificial neural network(ANN). This control method is applicable over the entire speed range which considered the limits of the inverter's current and voltage rated value. For each control mode, a condition that determines the optimal d-axis current $i_d$ for maximum torque operation is derived. This paper considers the design and implementation of novel technique of high performance speed control for IPMSM using Adaptive-FNN controller and ANN controller. The hybrid combination of neural network and fuzzy control will produce a powerful representation flexibility and numerical processing capability. Also, this paper reposes speed control of IPMSM using Adaptive-FNN and estimation of speed using ANN controller. The back propagation neural network technique is used to provide a real time adaptive estimation of the motor speed. The proposed control algorithm is a lied to IPMSM drive system controlled Adaptive-FNN and ANN controller, the operating characteristics controlled by maximum torque control are examined in detail. Also, this paper proposes the analysis results to verify the effectiveness of the Adaptive-FNN and ANN controller.

• 설비공학논문집
• /
• 제24권4호
• /
• pp.297-305
• /
• 2012

In recent large-scale semiconductor manufacturing clean rooms, the energy consumption of outdoor air conditioning systems to heat, humidify, cool and dehumidify incoming outdoor air represents about 45% of the total air conditioning load required to maintain a clean room environment. Therefore, the energy performance evaluation and analysis of outdoor air conditioning systems is useful for reducing the outdoor air conditioning load for a clean room. In the present study, an experiment was conducted to compare the energy consumption of outdoor air conditioning systems with a simple air washer, an exhaust air heat recovery type air washer and a DCC return water heat recovery type air washer. It was shown from the present lab-scale experiment with an outdoor air flow of 1,000 $m^3/h$ that the exhaust air heat recovery type and DCC return water heat recovery type air washer outdoor air conditioning systems were more energy-efficient for the summer and winter operations than the simple air washer outdoor air conditioning system and furthermore, the DCC return water heat recovery type one was the most energy-efficient in the winter operation.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2015년도 제46회 하계학술대회
• /
• pp.1034-1035
• /
• 2015

Watertight 25.8 kV/600 A/12.5 kA fault current limiters (FCLs) have successfully installed in five areas (Incheon, Seoul, Gyeong-gi, Daejeon, Suwon) on KEPCO power distribution line for the purpose of commercial demonstrations. The fault current limiting operation of this FCL, which includes functions of sensing, commutation, and reduction of fault currents, is perfectly completed within 1 cycle immediately after fault occurs. The performance of FCL was verified by short circuit test, impedance test, insulation test, temperature-rise test, and control test, etc at PT&T in LS industrial systems, which is the official certification institute in Korea. In 2013, and also the FCL field test was performed in order to test the protection coordination between conventional relays and FCL, on the 1.5 kA and 5.0 kA faults, which were made by connecting the Artificial Fault Generator (AFG) to the distribution line in test grid at KEPCO Power Testing Center. The next step of this project is to check the FCL conditions caused by real external environment, and acquire the various data from five regions installed with FCL. In this paper, we intend to explain the FCL specifications and performance characteristics, and check the expected effect by application of FCL to power distribution line based on the power system analysis of an application site.