• Journal of Electrical Engineering and Technology
• /
• v.12 no.2
• /
• pp.726-737
• /
• 2017

The use of energy storage systems (ESSs) has become a feasible solution to solve the wind power intermittency issue. However, the use of ESSs increases the system cost significantly. In this paper, an optimal power flow control scheme to minimize the ESS capacity is proposed by using the zero-phase delay low-pass filter which can eliminate the phase delay between the dispatch power and the wind power. In addition, the filter time constant is optimized at the beginning of each dispatching interval to ensure the fluctuation mitigation requirement imposed by the grid code with a minimal ESS capacity. And also, a short-term power dispatch control algorithm is developed suitable for the proposed power dispatch based on the zero-phase delay low-pass filter with the predetermined ESS capacity. In order to verify the effectiveness of the proposed power management approach, case studies are carried out by using a 3-MW wind turbine with real wind speed data measured on Jeju Island.

• The KIPS Transactions:PartC
• /
• v.11C no.1
• /
• pp.135-140
• /
• 2004

WLAH and WPAN technique are proposed as a home networking protocol in order to solve the problem of wireless communications and the bandwith extension. but, it is difficult to embed those technique to the home appliance devices because of economical efficiency and difficulty of standardization like a Bluetooth technique. In this paper, we suggEest a low-speed wireless protocol for wireless MODEM to control multiple devices. And we assure that this protocol not only maintain a accuracy and a characteristic of control information, but it is also suitable to a processor having low-processing ability and a processor embedded In the home appliance device through implementation of robot system and stable performance.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.23 no.2
• /
• pp.315-321
• /
• 1994

In order to prevent the postharvest decay and to promote the freshness retention of fruits and vegetables grapefruit seed extract(GFSE), natural microorganism control agent, was applied to the preservation of fresh fruits and vegetables. Freshfruits and vegetables treated with GFSE and stored in polyethylene film (0.1mm) at 1$0^{\circ}C$-15$^{\circ}C$ of natural low temperature low kept better qualities in color and texture than the GFSE -not- treated control. The treatment using GFSE ina 250ppm to 500ppm concentration seemed to be an effective one for the control of Botrytis cinerea isolated in red wine grapes. After 4 weeks of storage the firmness rate of cucumbers treated with the dilute GFSE was four times higher than that of non-treated ones. GFSE showed effective inhibitory action towards plant pathological bacteria and fungi which were involved in the decay of fruits and vegetables. Minimum inhibitory concentrations of GFSE towards them were in the range of 250ppm to 500ppm .Direct visualization of microbial cells and spores using electron microscopy showed microbial cells and fungal spores the function of which was destroyed by treating with the dilute solutions of GFSE. It was observed that GFSE would reduced disease damages and have bactericide & fungicide properties during the storage of such fruits and vegetables as egg plant, wild edible greens , kumquat, and kiwi fruit.

• Journal of Information Technology Applications and Management
• /
• v.30 no.6
• /
• pp.81-90
• /
• 2023

In aviation, with the rapid transformation of the mobility industry, UAMs are emerging to operate green low-altitude airspace in urban environments. In order for UAM aircraft to fly safely transporting passengers and cargo in low-altitude urban airspace, a traffic control system that supports the safe operation of the aircraft is essential. In particular, traffic control systems that reflect the characteristics of the flight environment, such as operating at low altitude in urban environments for a short period of time, are required. In this study, we define the definition of UATM and its main services that perform traffic control for the safe operation of UAMs. In addition, we analyzed the development trends of UATM systems based on domestic and overseas cases. Based on these analyses, we present the results of the concept design of the UATM system. After analyzing UATM development cases, we found that there is no commercialized UATM system, but overseas development is focused on systems that can integrate ATM and UTM. And we identified key stakeholders and interface data, and performed UATM system architecture and functional design based on the identified data. Finally, as a necessary element for the future development of UATM systems, we propose the establishment and advancement of UAM traffic flow management systems, the establishment of integrated control systems, and the development of interface with aircraft operation systems in preparation for the unmanned UAM aircraft.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.3
• /
• pp.455-464
• /
• 2019

The sensorless control based on the flux linkage of PM synchronous motors has excellent position estimation characteristics at low speeds. However, a limitation arises because the integrator of flux estimator is saturated by the DC offset generated during the analog to digital conversion(ADC) process of the measured current. In order to overcome this limitation, HPF with a low cutoff frequency is used. However, the estimation performance is deteriorated (Ed- the verb deteriorate already includes the meaning of 'problem') at high speed due to the low cutoff frequency, and increasing the cutoff frequency of the HPF induces further problems of phase leading and initial starting failure at low speeds. In this paper, the cutoff frequency of HPF was synchronized to the operation frequency of the motor: at low speeds the cutoff frequency was set to low in order to reduce the phase leading of the estimated flux, and at high speeds it was set to high to raise the DC offset removal performance. As a result, the operating range was increased by 200%. Furthermore, a phase compensation algorithm is proposed to reduce the phase leading of the HPF to less than 1.5 degrees over the full operating range. The proposed sensorless control algorithm was verified by experiment with a PM synchronous motor for a washing machine.

• Proceedings of the KIPE Conference
• /
• 2003.07a
• /
• pp.485-489
• /
• 2003

This paper presents the method of speed measurement for permanent magnet synchronous motor(PMSM) with the full-order observer using reduced-order state equation. This Is able to improve the operating performance at low speed. Therefore, by the proposed technique, a low resolution encoder can be used. Because it make the system improve the performance of speed response. The proposed method is verified to simulation and experiments.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.17 no.5
• /
• pp.13-20
• /
• 2013

In order to reduce seismic responses of a structure, additional dampers and vibration control devices are generally considered. Usually, control performance of additional devices are investigated for optimal design without variation of characteristics of a structure. In this study, multi-objective integrated optimization of structure-smart control device is conducted and possibility of reduction of structural resources of a building structure with smart top-story isolation system has been investigated. To this end, 20-story example building structure was selected and an MR damper and low damping elastomeric bearings were used to compose a smart base isolation system. Artificial earthquakes generated based on design spectrum of low-to-moderate seismicity regions are used for structural analyses. Based on numerical simulation results, it has been shown that a smart top-story isolation system can effectively reduce both structural responses and isolation story drifts of the building structure in low-to-moderate seismicity regions. The integrated optimal design method proposed in this study can provide various optimal designs that presents good control performance by appropriately reducing the amount of structural material and damping device.

• Journal of Institute of Control, Robotics and Systems
• /
• v.13 no.11
• /
• pp.1053-1059
• /
• 2007

This paper presents a target sate estimator(TSE) with low pass filter for improving the gun driving command. The ballistic computer uses target information such as predicted range, velocity, acceleration of a target to generate the gun command. We adopt the finite impulse response(FIR) filter as our TSE to shorten calculation time for the driving command and due to its inherent stability property. We also introduce a post-processing filter to reduce the high frequency components in the output signal of a TSE which may cause instability of gun driving. The first order low pass filter has been designed based on $H{\infty}$ criteria considering the noise characteristics. To show the validity of the present scheme, simulation results are given for the overall gun driving system including aircraft target information.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.521-524
• /
• 2005

To protect a satellite and electronic equipment from the acoustic loads generated by rocket propulsion system, many launch vehicle use acoustic blanket. Most high frequency region of the acoustic loads is reduced by nose fairing skins and acoustic barrier, but low frequency region is not. In order to control low frequency acoustic mode, we designed away resonator panel which was made of composite materials. This paper shows the absorption coefficient measurement result of resonator and SPL(Sound Pressure Level) reduction by using resonators in a rectangular cavity for experiment. Proper arrangement of acoustic resonators at each mode reduce effectively SPL around the satellite through changing boundary condition.

• Proceedings of the KIPE Conference
• /
• 2011.07a
• /
• pp.312-313
• /
• 2011

Recently, many industrial electric vehicles have been developed using various ac-motor drive technologies including field oriented vector control. Generally, a magnetic encoder is installed to have resistance to vibration and dust, and it is cost-effective. However, it is difficult to get an accurate rotor speed for high performance of vector control, because a resolution of the magnetic encoder is low and its phase accuracy is poor. In order to overcome this hardware problem, this study proposes a speed measurement algorithm using moving window for low-resolution magnetic encoder. This algorithm is experimentally tested and successfully applied to traction application of industrial electric vehicle.