• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.487-488
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• 2017

본 논문에서는 급전 코일과 집전 코일 간 공극 변화에도 일정한 공진 특성을 가지는 무선 전력 전송 시스템을 제안한다. 공진회로가 적용된 시스템의 회로특성은 인덕턴스나 커패시턴스와 같은 파라미터 값에 크게 의존하는데, 일정한 공진 특성을 가지기 위해서는 공극의 변화에도 일정한 인덕턴스가 유지되어야 한다. 제안하는 무선 전력 시스템은 공극이 감소할 때 페라이트 코어에 의해 인덕턴스가 증가하고 알루미늄 판에 의해 인덕턴스가 감소하는 상보적인 특성을 결합하여 공극변화에도 인덕턴스가 일정하게 유지되게 한다. 페라이트 코어와 알루미늄 판에 위치한 각 코일들의 기자력 비율을 조절할 경우 공극이 7 cm 에서 15 cm 까지 변하더라도 급 집전부의 자기 인덕턴스 변화는 ${\pm}1%$ 이내로 일정하게 유지되는 것을 확인하였다.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.254-255
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• 2017

공진형 컨버터에서 일반적으로 소프트 스위칭과 같은 조건을 만족시키기 위해 주파수 제어를 많이 사용한다. 그러나 전계결합형 무선전력전송 시스템 특성상 이격 거리나 정렬 오차 정도 따라 송 수신부를 연결하는 링크 캐패시턴스 값이 민감하게 변한다. 이런 시스템에서는 공진 주파수 추종과 동시에 시비율 제어가 필요하다. 송신부 앞 또는 부하단에 dc/dc컨버터를 추가하는 2단 구성은 시스템 효율이 1단 구성에 비해 낮다는 단점이 있다. 따라서 본 논문에서는 무선전력전송 시스템에 비대칭 하프 브릿지를 사용하여 시비율 제어와 주파수 추종제어를 할 수 있는 구조를 제안한다. 이는 시뮬레이션을 이용하여 검증한다.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.167-168
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• 2016

본 논문은 투명전극을 이용한 커패시티브 커플링 무선전력 전송에 관한 연구이다. 기존의 연구에서 유리를 유전체로 하여 큰 커플링 커패시터를 얻을 수 있었으며 이를 통해 전기자동차 무선전력 전송이 가능했었다. 하지만 동판을 이용하여 커패시터를 생성하는 경우 유리를 사용하는 응용분야에서는 시야확보의 문제점을 가진다. 이러한 문제점을 해결하기 위한 방식으로 전기전도성이 높은 투명전극 사용방식을 제안한다. 제안하는 방식의 타당성 검증을 위해 모의실험을 통한 손실과 효율을 분석했다. 또한 실험의 타당성 검증을 위해 동판만으로 구성한 커패시터, 투명전극과 동판으로 구성한 커패시터를 이용해 실제 200W급 송 수신 회로를 설계 및 제작하여 비교 분석 하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.678-683
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• 2010

This paper presents a wireless (contactless) charging technique with a new core material called permalloy. For charging portable devices wirelessly, ferrosilicon or ferrite has been conventionally used. Due to high permeability of permalloy, charging efficiency can be significantly improved and subsequently this high efficiency increases charging distance between charger and portable devices. Comparative experimental studies demonstrate that the charging performance and efficiency with permalloy employed are significantly improved. The proposed wireless charging techniques can be used to charge portable devices efficiently.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.275-280
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• 2013

This paper presents an optimizing method for wireless charging system, specifically focused on the capsule endoscope applications. In order to increase the wireless power transfer efficiency of electro-magnetic resonance coupled coils, this paper investigates the impact factors of the power transfer efficiency in small battery capacity system and proposes a efficiency optimizing method based on frequency control. Simulation results show that the proposed efficiency optimal control method can effectively stabilize the wireless power transfer efficiency so as to successfully solve the main issue of transfer efficiency variation with distance and as well as parasitic element.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.70-74
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• 2015

In this paper, two-dimensional resonant transmitter and receiver for WPT is designed and implemented using method that use $90^{\circ}$ phase shifted input power to orthogonal transmitter. Mutual inductance is minimized by using proposed each orthogonal coil of receiver and the method that inputs $90^{\circ}$ phase shifted power is used to radiate magnetic energy into two dimension. This method facilitates two dimensional resonant WPT by solving power efficiency degradation problem according to location in general WPT. The resonance frequency is 6.78 MHz and the distance between transmitting and receiving resonator is 200 mm. The transfer efficiency of the proposed wireless power transfer system is higher than 40 % at all direction.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7B
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• pp.649-658
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• 2009

Due to limited size and limited battery lifetime of sensor node, one has to address the power saving issue in wireless sensor network. The existing power saving algorithm based on data reuse was proposed for the cluster structured wireless sensor network. We state the problem of existing power saving algorithm and propose new power saving algorithm for tree structured wireless sensor network. The proposed algorithm reduces power consumption by buffering the sensed data at the selected relay node for its data lifetime. The optimum buffering node is selected so that the power saving gain is maximized and at the same time, power consumption among sensor nodes are equally distributed in the network. With computer simulations, it is shown that the proposed algorithm outperforms the conventional algorithm in terms of power saving gain.

• Journal of Advanced Navigation Technology
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• v.9 no.2
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• pp.121-130
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• 2005

In this paper, we designed and fabricated the VHF wireless transmitter for air traffic control. Fundamental performance of the investigated wireless transmitter is designed and fabricated to satisfy existing commercial wireless transmitter specification for air traffic control. 25 W and 50 W of output power can be generated by changing the power amplification part only. It is based on transmitting voice communication using AM modulation. Investigated wireless transmitter for air traffic control consists of four module parts: power supply, control, low power transmission and power amplification. We designed 1W transmitter to operate without power amplification part. It can be used properly in a basic component of CNS/ATM.

• Journal of Digital Contents Society
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• v.19 no.7
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• pp.1373-1379
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• 2018

Wireless sensors in Internet of Things are getting closer to our daily lives. Since wireless sensors have limited battery power, energy efficient schemes should be employed. In this paper, we analyzed a system by using stochastic model and then solved an optimization problem, given that the gathered sensor data are aggregated before being transmitted to the sensor servers from a wireless sensor device. Using the developed model, we also proposed a optimal solution to determine the energy efficient sensor data transmitting interval. We also conducted performance evaluations of our proposals using numerical examples.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.4
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• pp.793-797
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• 2004

Wireless sensor networks use battery-operated computing and sensing devices. And It can be expected to be deployed in an ad hoc networs. MAC is different from traditional wireless MACs such as IEEE 802.11 in almost every way. so self-configuration and power saving in sensor network are very important goals, while per-node fairness and latency are less important. In this paper, so we use a given prototype for efficient energy conservation to reduce power consumtion that is one of the important character in sensor network and compare energy consumption and collision with IEEE 802.11 MAC. finally we conclude the paper and analyze it.