• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1051-1053
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• 2003

Flywheel Energy Storage System (FESS) consists of a high-speed flywheel with an integral motor/generator suspended on magnetic bearings and in an evacuated housing. Permanent magnet (PM) machines as the FESS motor/generator are a popular choice. since there are no excitation losses which mean substantial increase in the efficiency. In this paper, the basic design and the steady-state performances of a permanent magnet synchronous high speed motor/generator for FESS are presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1071-1077
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• 2000

Recently, several attempts have been made to apply high Tc superconductor bearings of thrust type to flywheel energy storage system (FESS) throughout the world. Radial type superconductor bearings, however, have never been tried to the real FESS. KEPRI has developed its own radial type bearings and is now currently applying them to a FESS designed by KIMM, for the first time. In this paper preliminary test results of bearing performance and dynamic behavior of the flywheel rotor system mounted on them are presented. The dynamic properties, i.e, stiffness and damping, of the superconductor bearings were experimentally estimated using the static loading test as well as the impact test. The test revealed that stiffness value of the present superconductor bearings is about 67,700N/m and the damping value 29Ns/m. It was also found out that these bearings have some levitation drift problems due to excessive vibrations encountered while passing through the critical speeds. With recommend backup bearings to limit the vibration amplitudes of the rotor it is predicted that the flywheel rotor will show stable operations in the design speed range.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.86-88
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• 2008

The rotational loss is one of the most important problems for the practical use of the high power Flywheel Energy Storage System (FESS). This rotational loss is divided as the mechanical loss by windage and bearing and iron loss by hysteresis loop and eddy current in the part of the magnetic field. So, In this paper, a double-sided PMSM/G without the iron loss is designed by analytical method of the magnetic field and estimation of the back-EMF constant represented as the design parameter. This design model consists of the double-sided PM rotor with Halbach magnetized any and coreless 3-phase winding stator. The results show that the double-sided PMSM/G without iron loss can be applicable to the high power FESS.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.226-227
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• 2011

본 논문에서는 전력 시스템의 저주파 진동을 효율적으로 억제하기 위하여 기존의 PSS 를 이용하는 방법 대신 FESS를 적용하는 방법을 제시하였다. FESS PID 제어기의 최적 파라미터를 선정하기 위하여 GA를 이용한 방법을 제시하였다. 최적화 파라미터 선정시 사용되는 평가함수를 2가지로 선정하여 선정된 파라미터를 이용하여 FESS PID 제어성능을 평가하였다. 다양한 동작 조건하에 몇 가지 외란이 발생한 경우 비선형 시뮬레이션을 통하여 기존의 PSS를 이용한 방법과 동특성을 비교 고찰하였다.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.7
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• pp.771-777
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• 2013

This paper describes a study of major shipyard's electrical network and simulation of applying flywheel energy storage system on the electrical network at shipyard for shore-power to ships and offshore plants in order to save fuel consumption on engines, mitigate voltage sags, and prevent blackout due to pulsed load and fault, resulting in reduction of air emission into atmosphere. The proposed energy recycling method with FESS (Flywheel Energy Storage System) can be applied for electrical power system design of heavy cranes at shipyards.

• Journal of KSNVE
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• v.9 no.5
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• pp.891-898
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• 1999

The purpose of Superconducting Magnetic Bearing Flywheel Energy Storage System (SMB-FESS) is to store unused nighttime electricity until it is needed during daytime. An analytical model of the SMB-FESS is necessary to identify the system behavior. At first, we have to model the superconducting magnetic bearing. Modeling the SMB is same as estimating the bearing parameter. The theoretical modal parameter is calculated through the equation of motion and the experimental modal parameter is estimated through the impact testing (modal testing). The bearing parameter is searched by using the non-linear least square method until the theoretical result corresponds to the experimental result. The suggested modeling method is verified by comparing experimental and analytical frequency response function.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.485-490
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• 2004

Flywheel Energy Storage System(FESS) consists of a high speed flywheel with an integral motor/generator suspended on non contact bearings and in an evacuated housing. Permanent magnet machines as the FESS motor/generator are a popular choice, since there are no excitation losses which means substantial increase in the efficiency. In this paper, the structural design method of rotor retainer for a high speed motor/generator are presented.

• Progress in Superconductivity
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• v.13 no.1
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• pp.40-46
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• 2011

A superconductor flywheel energy storage system (SFES) is an electro-mechanical battery which transforms electrical energy into mechanical energy for storage, and vice versa. A 10 kWh class flywheel energy storage system (FESS) has been developed to evaluate the feasibility of a 35 kWh class SFES with a flywheel $I_p/I_t$ ratio larger than 1. The 10 kWh class FESS is composed of a main frame, a composite flywheel, active magnetic dampers (AMDs), a permanent magnet bearing, and a motor/generator. The flywheel of the FESS rotates at a very high speed to store energy, while being levitated by a permanent magnetic bearing and a pair of thrust AMDs. The 10 kWh class flywheel is mainly composed of a composite rotor assembly, where most of the energy is stored, two radial and two thrust AMD rotors, which dissipate vibration at critical speeds, a permanent magnet rotor, which supports most of the flywheel weight, a motor rotor, which spins the flywheel, and a central hollow shaft, where the parts are assembled and aligned to. The stators of each of the main components are assembled on to housings, which are assembled and aligned to the main frame. Many factors have been considered while designing each part of the flywheel, stator and frame. In this study, a 10 kWh class flywheel energy storage system has been designed and constructed for test operation.

• Korean Journal of Poultry Science
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• v.35 no.1
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• pp.21-27
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• 2008

This study was conducted to evaluate the effects of mineral and vitamin-enhanced supplementation on egg production, egg quality and concentrations of calcium and phosphorus in serum of spent laying hens. A total of 240 (72-wk-old) Hyline brown commercial hens were used in the current trial for 4 weeks. Dietary treatments included 1) CON (basal diet), 2) ESS1 (basal diet + Egg shell strengthen 0.1%), 3) ESS2 (basal diet + Egg shell strengthen 0.2%) and 4) FESS (basal diet + Fe egg shell strengthen 0.2%). During the overall period, egg production was increased in CON and ESS2 treatments compared with ESS1 treatment (P<0.05). Egg shell breaking strength and final egg shell thickness were significantly higher in ESS2 treatment than CON and FESS treatments (P<0.05). Egg yolk color index was significantly lower in ESS1 treatment than other treatments (P<0.05). Moreover, Haugh unit was significantly lower in ESS1 and FESS treatments than CON treatment (P<0.05). Mineral- and vitaminenhanced supplementation did not affect either egg shell color or calcium and phosphorus concentration in serum. In conclusion, mineral- and vitamin- enhanced supplementations of laying hens diet are helpful in improving egg shell breaking strength and thickness by supplementation of Egg shell strengthener 0.2%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.678-685
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• 2016

Deglutition inspection has been the gold standard for inspection of dysphagia using a penetration device of the division of radiology to date. However, inspection using an endoscope has facilitated diagnosis of dysphagia in recent days. In this study, we compared the results of VFSS alone with those of VFSS combined with FEES to determine if the detection rate of penetration, aspiration, and pharyngeal residue increased. This study evaluated at 130 persons who underwent both VFSS and FEES from December 2013 through March 2014, and used VFSS (FELAVISION, SHIMADZU) and FESS (EVIU LUCERA CV-260SL, OLYMPUS) as devices. After preparing barium diluted solution, yogurt that diluted barium and rice that diluted barium in 2.5 ml, 5 ml, 10 ml by modifying Logemann's protocol in part, and having subjects take the solution, this study confirmed pharyngeal residue, penetration, aspiration etc. VFFS and FEES using full HD video revealed aspiration in 36 of the 130 patients in both inspections. Additionally, aspiration was discovered in 36 patients upon VFFS, but in 41 upon FESS. Although FEES was more sensitive at diagnosing dysphagia, the two inspection methods are complementary, so diagnostic value will be greatly improved when the endoscope operating method and accurate fluoroscopic inspection are combined.