• 조명전기설비학회논문지
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• 제29권5호
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• pp.41-49
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• 2015

In this paper, we studied an optimal design and efficiency improvement of the BLCD motor used in home electronic appliance. The number of stator slots is chosen depending on the rotor poles, phase number, and the winding configuration. In general, a fractional slots/pole design is preferred to minimize cogging torque. To reduce the winding resistance, we reduced the coil length and we improved the coil space factor. We proposed three types of stator slot shape design for the optimal BLDC motor design. One of them, U-type slot shape is a best optimal design, it proved by the simulated and tested. Optimal design of essential parameters aiming at high winding factor are presented to create for a high-quality system implementation. Design analysis is verified by testing and building a prototype motor.

• 한국전산구조공학회논문집
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• 제25권4호
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• pp.347-354
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• 2012

형상기억합금의 복원력 및 복원량은 열 하중 및 기계적 하중으로 인한 마르텐사이트 상에서 오스테나이트 상으로의 상변이에 의한 상변형률 발생에 기인한다. 복원력 및 복원량은 초기 형상 및 하중 부여 방식에 따라 차이가 발생하는데 적절한 설계 전략없이 상변형률에만 의지한 경우 큰 복원력은 발생할 수 있어도 큰 복원량을 기대하기는 어렵다. 이는 형상기억합금의 큰 복원력과 작은 복원량 간의 비대칭성에 기인하며 형상기억합금의 효율적인 이용에 걸림돌이 된다. 본 연구에서는 형상기억합금의 상변이로 발생하는 복원량을 극대화하는 방안으로 형상기억합금 선이 이중으로 감겨있는 이중 나선 구조 형상기억합금 스프링을 제안한다. 그리고 열 하중에 의해 발생하는 복원량을 예측하고 단일 나선 구조 형상기억합금 스프링과 비교 분석하여 이중 나선 구조 형상기억합금 스프링이 단일 나선 구조 형상기억합금 스프링보다 성능 비대칭성을 보다 완화시킬 뿐만 아니라 복원력 대비보다 큰 복원량을 가짐을 보였다.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.315-317
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• 2002

The value of I$_{c}$(critical current) in HTS (High Temperature Superconducting) tape has a great influence on B(equation omitted) (magnetic field amplitude applied perpendicular to the tape surface). Therefore, I$_{c}$ of HTS magnet is determined by not only operating temperature but also the B(equation omitted). In shape design of field coil for the HTS motor, a method to reduce the B(equation omitted) and to determine operating current should be considered in order to optimal design. On the basis of the magnetic field analysis, this paper deals with various field coil shape to obtain operating current of HTS motor by using analytical method. And also this paper discusses the operating current of 100hp class HTS motor by using I$_{c}$-B(equation omitted) curve.curve.

• Journal of electromagnetic engineering and science
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• 제16권4호
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• pp.210-213
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• 2016

This paper presents a wireless power charging system for rechargeable batteries. Recently, misalignment between transmitting coil and receiving coils has been a significant factor to wireless power charging systems, which are prone to lateral and angular misalignment. Unfortunately, the batteries can be easily rolled because of the shape, and coils are often misaligned while charging devices, in practical situations. This paper presents the wireless power battery charging system. In order to solve the angular misalignment, two perpendicular coil having structure of 'plus (+)' shape was proposed. To validate the results, the proposed wireless power charging system was implemented at 6.78 MHz using loosely coupled resonant coils, and the system was verified as being robust to misalignment.

• 센서학회지
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• 제26권4호
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• pp.245-250
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• 2017

A novel method to implement a birdcage-type receiving coil sensor for use in a magnetic resonance imaging(MRI) system has been demonstrated employing a flexible printed circuit board (FPCB) fabrication technique. Unlike the conventional methods, the two-dimensional shape of the coil sensor is first implemented as a FPCB and then it is attached to the surface of a cylindrical supporting structure to implement the three-dimensional birdcage-type coil sensor. The proposed method is very effective to implement object-specific MRI coil sensors especially for small animal measurements in research and preclinical applications since the existing well-developed FPCB-based techniques can easily meet the requirements on accuracies and costs during coil implement process. The performances of the coil sensor verified through $^1H$ 1.5T MRI measurements for small animals and it showed excellent characteristics by providing a high spatial precision and a high signal-to-noise ratio.

• Journal of electromagnetic engineering and science
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• 제17권3호
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• pp.126-132
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• 2017

In this study, we designed, measured, and analyzed a rearranged L-shape magnetic resonance coupling wireless power transfer (MR-WPT) system for practical applications with laptops. The typical four resonator MR-WPT (Tx part: source loop and Tx coil; Rx part: Rx coil and load loop) is difficult to apply to small-sized stationary and mobile applications, such as laptop computers, tablet-PCs, and smartphones, owing to the large volume of the Rx part and the spatial restrictions of the Tx and Rx coils. Therefore, an L-shape structure, which is the orthogonal arrangement of the Tx and Rx parts, is proposed for indoor environment applications, such as at an L-shaped wall or desk. The relatively large Tx part and Rx coil can be installed in the wall and the desk, respectively, while the load loop is embedded in the small stationary or mobile devices. The transfer efficiency (TE) of the proposed system was measured according to the transfer distance (TD) and the misaligned locations of the load loop. In addition, we measured the TE in the active/non-active state and monitor-open/closed state of the laptop computer. The overall highest TE of the L-shape MR-WPT was 61.43% at 45 cm TD, and the TE decreased to 27.9% in the active and monitor-open state of the laptop computer. The conductive ground plane has a much higher impact on the performance when compared to the impact of the active/non-active states. We verified the characteristics and practical benefits of the proposed L-shape MR-WPT compared to the typical MR-WPT for applications to L-shaped corners.

• 설비공학논문집
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• 제21권5호
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• pp.291-296
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• 2009

Ice accumulating system patterned ice-an-coil is the way of refrigerating regenerative materials on the surface of copper-tube inserted into the inside of ice-storage. The study experimented to understand ice-an-coil type ice making characteristics according to changing shape of ice making tube. The experiment were carried out under various conditions, that used brine temperature($-l0^{\circ}C$, $-6^{\circ}C$) brine flow rate(l.0m/s, 1.8m/s) and inlet water temperature($6^{\circ}C$, $12^{\circ}C$) etc. Mass of ice per making area increased according to the decrease of the brine temperature and inlet water temperature, but that was increased according to the increase of the brine flow rate. And I set up two hypotheses and compared the capacity of ice-making of the two cases; each had the same thermal area and one had an round-shaped copper tube but the other had an oval-shaped copper tube.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.352-355
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• 2004

The objective of this work is to develop a new design method to find optimal coils, especially the optimal coil configuration of an optical pickup actuator. In designing actuator coils, the developed Lorenz force in the coils along the desired direction should be made as large as possible while forces and torques in other directions should be made as small as possible. The design methodology we are developing is a systematic approach that can generate optimal coil configurations for given permanent magnet configurations. To consider the best coil configuration among all feasible coil configurations, we formulate the design problem as a topology optimization of a coil. The present formulation for coil design is noble in the sense that the existing topology optimization is mainly concerned with the design of yokes and permanent magnets and that the optimization of actuator coils is so far limited within shape or size optimization. Though the present design methodology applies to any problem, the specific design example considered is the design of fine-pattern tracking and focusing coils.

• 한국정밀공학회지
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• 제33권7호
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• pp.601-606
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• 2016

In this paper, an energy harvester is developed that has advantages regarding piezoelectric noise minimization, mass production, and an easily available environmental energy source, electromagnetic induction, as well as low-frequency bandwidth and high amplitude. A process for fabricating a three-dimensional multilayered planar coil using micro-electro-mechanical systems (MEMS) on a flexible printed circuit board FPCB is introduced. Optimal shape and size were calculated via internal resistance and inductance, and a prototype was fabricated through the MEMS procedure while considering the possibility of mass production. Although the internal resistance matched the designed value, the electromotive force generated did not reach the intended amount. The main reason for the decrease in efficiency was the low area of coil outskirt exposed to the magnetic field while there was relative motion between the magnet and the coil.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 B
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• pp.327-329
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• 2000

This paper present the characteristic improvements of one-coil coin type vibration Motor. Rotor is consist of coreless coil and 4 segment commutator. Magnet is 4 pole, z direction magnetized. This one-coil coin type vibration motor has simple mechanical structure and good efficiency. So production cost is lower than other having 2 or more coils coin type motor but it has the weak points. That is small vibration magnitude and dead zone. Modifying the shape of rotor, vibration magnitude is increased. To avoid the dead zone we attached more magnetic body on rotor. As result we show the optimal position of magnetic body.