• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.78-78
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• 2009

In this study, multilayer piezoelectric ceramics was manufactured using the PMW-PNN-PZT ceramics. Then, their physical characteristics for applicaton of electric power generation were investigated according to the numbers of multilayer. With increasing the numbers of multilayer, effective electromechanical coupling factor($k_{eff}$) and capacitance were decreased and increased, respectively.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2007년도 The 1st International Symposium on Advanced Magnetic Materials
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• pp.17.2-17.2
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• 2007

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.1081-1083
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• 1999

The capacitive coupling technique has been used as conventional method for PD detection on the power cable line. Recently, however PD measurement using by high frequency is known to have an excellent sensitivity comparison with low frequency on-site. In this paper, the high frequency characteristic of two type of metal foil sensor was studied and the technique was proved to be more effective diagnostic method than conventional method for qualification of EHV cable and accessories.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.149-149
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• 2009

본 연구는 고압전력용 중전기기의 몰드절연 및 옥외용 LED의 절연소재는 기기내부에서 발생된 열에너지를 외부로 방사시키는 것이 무엇보다 중요한 것이다. 이런 이유로 고압전력용 전력기기 대부분은 상당한 체적분을 가지고 있기에 초절연을 가지면서 고열전도를 갖는 나노콤포지트를 개발하기위해 에폭시 메트릭스 기반 질화알루미륨의 표면 처리를 실시하여 에폭시 AIN Nanocomposites를 제조하였다. 나노입자의 균질분산은 나노콤포지트 열전도와 초절연성능에 크게 영향을 주게 된다. 이런 소재개발을 위해 에폭시메트릭스에 나노입자의 충진함량을 3wt%로 하였다. 전처리공정을 통하여 에폭시-나노콤포지트에 두 종류의 금속성 coupling agent (Tyzor TE, Tyzor AA-75)를 질화알루미륨 나노입자 표면처리를 건식법으로 실시하였다. 제조된 Epoxy-AIN Nanocomposites의 열적특성과 전기적 특성을 측정하였다. 전기적특성으로 초절연성의 특성인 형상파라미터가 10.93을 그리고 척도파라미터는 176 kV/mm로서 Weibull Plot 누적확률밀도로서(63.2%)의 통계분석된 값을 얻었다. 또한 열적특성 평가를 위해 유리천이온도와 DMA의 온도특성를 조사하였고, 열적.전기적 특성과 나노콤포지트 내부분산(내부 모폴로지:TEM영상)와 연관되어 연구한 결과, 상당히 일치한 결과를 얻을 수 있었다.

• 한국초전도ㆍ저온공학회논문지
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• 제16권3호
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• pp.21-25
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• 2014

As wireless power transfer (WPT) technology using strongly coupled electromagnetic resonators is a recently explored technique to realize the large power delivery and storage without any cable or wire, this technique is required for diffusion of electric vehicles (EVs) since it makes possible a convenient charging system. Typically, since the normal conducting coils are used as a transmitting coil in the CPT system, there is limited to deliver the large power promptly in the contactless EV charging system. From this reason, we proposed the combination CPT technology with HTS transmitting antenna, it is called as, superconducting contactless power transfer for EV (SUWPT4EV) system. As the HTS coil has an enough current density, it can deliver a mass amount of electric energy in spite of a small scale antenna. The SUCPT4EV system has been expected as a noble option to improve the transfer efficiency of large electric power. Such a system consists of two resonator coils; HTS transmitting antenna (Tx) coil and normal conducting receiver (Rx) coil. Especially, the impedance matching for each resonator is a sensitive and plays an important role to improve transfer efficiency as well as delivery distance. In this study, we examined the improvement of transmission efficiency and properties for HTS and copper antennas, respectively, within 45 cm distance. Thus, we obtained improved transfer efficiency with HTS antenna over 15% compared with copper antenna. In addition, we achieved effective impedance matching conditions between HTS antenna and copper receiver at radio frequency (RF) power of 370 kHz.

• 한국생산제조학회지
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• 제20권4호
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• pp.440-445
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• 2011

This paper presents a new regenerative brake system of electric vehicles that employs a continuous variable transmission(CVT) and a flywheel. The developed device has advantages over existing regenerative brakes from a standpoint of reliability and versatility in actual driving conditions. The system consists of a CVT, two wheels, a flywheel, a coupling and auxiliary powertrain components. The CVT is designed as a combination of two cones and a roller, which causes the velocity difference between the wheel and the flywheel. The power flow of the flywheel system is controlled by the CVT roller and the coupling through step motors. A prototype has been developed and then its performance has been investigated for various operating conditions. Results show that the storage efficiency of the flywheel is much affected by the vehicle's velocity and it is reduced below 20% for high speed, as compared to the 25% efficiency for an ideal condition. The CVT is a primary factor for lowering the flywheel efficiencies due to large friction and slipping between the cone and the roller.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.211-225
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• 2011

Railroad signalling systems are to control intervals and routes of trains. There are ATS(Automatic Train Stop), ATP(Automatic Train Protection), ATO(Automatic Train Operation) and ATC(Automatic Train Control) system. Trains are operated in the section which is met on the signalling system because various signalling systems are used in Korea. On the other words, trains are not operated in the section which is used in the other signalling system. To solve this problem, recently combined on-board system has been developed. The combined on-board system is designed by doubling the ATS, ATP and ATC system. Information signal is received by magnetic sensors in the ATC system and is received by antennas in the ATS and ATP system. Therefore, it is possible to arise transmission problems by magnetic coupling. In this paper, electric model of the ATS and ATP antenna is suggested and interference frequency by the magnetic coupling between the ATS and ATP antenna is estimated numerically. As a results of the magnetic coupling, the value of the magnetic coupling is presented without magnetic induction.

• 한국전자파학회논문지
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• 제17권6호
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• pp.501-510
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• 2006

본 논문에서는 플랜지된 평행 평판 도파관의 슬릿을 통한 도체 스트립과의 전자기적인 결합을 연구하였다. 슬릿의 전계와 스트립의 유기 전류에 관한 결합 적미분 방정식을 유도하고 모멘트 방법으로 풀었다. 몇 가지 슬릿을 통한 최대 결합 현상들의 특성을 도체 스트립의 위치, 동작 주파수, 스트립의 길이 등 다양한 파라미터에 대한 슬릿의 등가 어드미턴스와 결합 전력의 변화를 통해 조사하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.221-226
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• 2005

In this paper, a dynamic model for the rotor shaft-coupling-blade system is developed. The blades are attached to a disk and driven by an electric motor shaft which is flexible in torsion. We assumed that the shaft torsional flexibility is lumped in the flexible coupling which is usually adopted in rotor systems. The Lagrangian approach with the small deformation theory for both blade-bending and shaft-torsional deformations is employed for developing the equation of the motion. The assumed modes method is used for estimating the blade transverse deflection. The numerical results highlight the effects of both structural damping of the system and the torsional stiffness of the flexible coupling to the dynamic response of the blade. The results showed strong coupling between the blade bending and shaft torsional vibrations in the form of inertial nonlinearif, stiffness hardening and softening.

• 한국전자파학회논문지
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• 제25권4호
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• pp.426-433
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• 2014

고고도 핵폭발로 인해 고고도 전자기 펄스(HEMP)가 발생한다. 본 논문에서는 Bell 연구소와 IEC 61000-2-9 기준에 제시된 HEMP 파형이 해군 함정의 복사성 결합 통로와 전도성 결합 통로를 통해 입사할 때 침투하는 침투 전계 특성을 비교 검토하였다. 또한, 두 가지 종류의 결합에 대한 효과를 분석하고, 방호 대책을 제시하였다. 시뮬레이션 결과, IEC 61000-2-9 기준이 Bell 연구소의 기준보다 저주파수 대역을 제외하고 침투전계가 크므로 좀 더 엄격한 기준으로 볼 수 있고, 따라서 IEC 61000-2-9의 기준을 해군내 HEMP 기준으로 제시하였다. 최종적으로 HEMP 방호 대책으로 차폐 코팅, 허니컴 통풍구, TVS 소자 등을 이용하여 미국방부 기준에 부합하는 것을 확인하였다.