• 전기학회논문지
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• 제63권12호
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• pp.1732-1736
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• 2014

Generally, traction motors for railway vehicles are inferior to that of electric vehicle in terms of output density. Traction motors for railway vehicles are relatively free of spatial constraints than motors electric vehicles, but in terms of whole system efficiency, increasing output density of traction motor is helpful. In this paper, using Halbach magnet array structure, output density of traction motor for 40kW class tram was elevated. This paper introduce detailed design process of the Halbach magnet array structure applied model, and check the affects on output characteristics by parameters like rotor shape, airgap diameter and pole ratio. Also, electrical output characteristics were compared between typical SPMSM model and Halbach magnet array model, which has same output size.

• 지질공학
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• 제16권3호
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• pp.255-263
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• 2006

지표가 불규칙한 지형에서 경사시추공을 이용한 단극-쌍극자 배열 전기비저항 토모그래피 탐사를 보면, 우리는 시추공안에 있는 전류원과 지표의 지형기복 사이의 최단거리에 위치한 전위전극에서의 극성변화, 지형기복에 따른 거리계수와 포텐셜의 변화 및 모델링에서 경사 시추공에 위치한 전극과 절점의 공간적인 불일치 등을 고려할 수 있다. 요소분할 방법은 시추공이 곡선이거나 경사져 있을 경우와 하나의 요소에 여러 개의 전극이 있을 때 각 전극에 대한 절점 좌표를 지정할 수 있기 때문에 매우 효과적인 방법이라고 본다. 시추공과 지형기복이 동일한 경사를 갖는 경우에서의 역산 결과는 매우 좋은 영상으로 나타났으며 최소자승근의 오차가 안정적으로 수렴되는 경향을 보였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권7호
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• pp.315-322
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• 2001

High speed brushless permanent magnet(PM) machines need a key technology to minimize the iron core losses in stator and the eddy current losses in the retained sleeve and magnets caused by slotting harmonics. Thus, slotless or iron-coreless brushless PM machines have been applied for a very high rotational speed and/or the ripple-free torque. Unfortunately, slotless or coreless PM machines have lower open-circuit field than slotted and/or iron-cored types, which cause to reduce power density. Fortunately, Halbach array can generate the strong magnetic field systems without additional magnetic materials. In this paper, the 4-pole Halbach array is applied to the high speed machine and is compared with the radial magnetized PM array in field system. The iron-/air-cored stator of PM machine is constructed with/without winding slots. Open circuit magnetic fields of each type are presented from the analytical method and finite element method. Consequently, it is confirmed that the Halbach array field system with slotless stator is more suitable to the high speed motor because it has high flux density, sinusoidal flux distribution than others.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.650-652
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• 2000

Proposed slotless PM machine is constructed without stator winding slots. Its stator magnetic material is in the form of a ring and winding have a toroidal configuration and its rotor consists of a 4-pole Halbach array or radially magnetized PM rotor. Thus, airgap flux density distribution and induced emf waveform are essentially sinusoidal. Open circuit magnetic fields and developed torque of each type are presented from the analytical method and finite element method.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.961-965
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• 2009

Using much electric resistivity survey to design or preservation administration of facilities. However, By survey method that electric resistivity survey grasps special quality in base by potential difference creating artificial current in underground, Is influenced in electric resistance propensitys of various underground utilities in base. This Study selects dam 1 place that could grasp well underground situation and studied electricity interference effect by effect of underground utilities. Grasp underground utilities of dam interior, and control and observed accuracy with survey wave because various pole space. Through this Study, wish to present survey method of electric resistivity survey at design or survey of preservation administration dimension after with drawn result.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.178-183
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• 2003

This paper deals with transmission loss characteristics of the panel type silencer to control low frequency noise. The panel type silencer is composed of many Helmholtz resonators by side branch. Each resonator has high transmission loss on the narrow band of its resonance frequency. Direct arrangement of the resonators increases mainly the magnitude of transmission loss. If we arrange the resonators in a row, the peak and band of transmission loss are increased. This makes the resonator array to have high transmission loss in the broader band. Using this idea, we design a silencer that has broader band characteristics and smaller volume.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.337-339
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• 2001

High speed brushless permanent magnet (PM) machines are a key technology for electric drives and motion control systems for many application, since they are conductive to high efficiency, high power density small size and low weight. Proposed slotless PM machine is constructed without stator winding slots. Its stator magnetic material is in the form of a ring and winding have a toroidal configuration and its rotor consists of a 4-pole Halbach array or radially magnetized PM rotor.

• 제어로봇시스템학회논문지
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• 제22권1호
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• pp.53-58
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• 2016

Various jumping robot platforms have been developed to carry out missions such as rescues, explorations, or inspections of dangerous environments. We suggested a jumping robot platform using energy conversion of the elastic body like the bar of a pole vault, which is the main part in which elastic force occurs. The compliant link was optimized by an optimization method based on Taguchi methodology, and the robot's leaping ability was improved. Among the parameters, the length, width, and thickness of the link were selected as design variables first while the others were fixed. The level of the design variables was settled, and an orthogonal array about its combination was made. In the experiment, dynamic simulations were conducted using the DAFUL program, and response table and sensitivity analyses were performed. We found optimized values through a level average analysis and sensitivity analysis. As a result, the maximum leaping height of the optimized robot increased by more than 6.2% compared to the initial one, and these data will be used to design a new robot.

• 한국정보통신학회논문지
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• 제14권9호
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• pp.2157-2163
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• 2010

본 논문은 신호의 도래 방향 측정에 관한 연구로써, 어레이 안테나에 입시되는 신호의 위상차를 활용하여 방향을 추정하는 알고리즘인 CVDF(Correlative Vector Direction Finding)를 적용하여 방향탐지 정확도를 높이기 위해서는 기본적으로 안테나로부터 얻어지는 위상차 패턴이 이상적인 정현파 패턴을 가져야 한다. 그러나 실 환경에서 원형으로 안테나를 배치후 측정되는 위상차 패턴은 특정 주파수 대역, 특정 방위에서 왜곡되어 나타날 수 있다. 그 이유는 안테나를 원형 배열 구조로 배치함으로써 안테나 각 소자간의 간섭 및 중앙 센터폴(원형배열의 중앙에 위치하는 안테나 지지대)의 영향으로 인한 위상 패턴의 왜곡이 발생할 수 있다. 본 논문에서는 기존 CVDF 알고리즘을 적용했을 때의 위상 왜곡 현상에 의해 저하되는 방향탐지 능력을 개선시키기 위한 방법으로, 위상을 측정하기 위한 안테나 조합의 실시간 변경 방법 및 안테나 빔패턴을 활용하는 방법 등을 제안하였고, 실험 및 결과분석을 통해 방향탐지 성능이 개선됨을 확인하였다.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.2045-2049
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• 2018

An antenna arrays for a satellite navigation systems require more antenna elements to mitigate multiple jamming signals. In order to maintain the small array size while increasing the number of antenna elements, miniaturization technique is essential for antenna design. In this work, an electrically small circular microstrip patch antenna with a 3 dB hybrid coupler is designed as an element antenna, where the 3 dB hybrid coupler can yield the circularly polarized radiation characteristic. The miniaturized element antenna typically has too large capacitance in GPS L1 and GLONASS G1 bands, making it difficult to match with a single stand-alone non-Foster matching circuit (NFMC) in a stable state. Therefore, we propose a new matching technique, referred to as the hybrid matching method, which consists of a NFMC and a passive circuit. This passive tuning circuit manages reactance of antenna elements at an appropriate capacitance without a pole in the operating frequency range. The antenna array is fabricated, and the measured results show a reflection coefficient of less than -10 dB and an isolation of greater than 50 dB. In addition, peak gain of the proposed antenna is increased by 22.3 dB compared to the antenna without the hybrid matching network.