• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.3
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• pp.335-340
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• 2011

In the study, a tangible interface using iPhone is proposed to control a mobile robot, instead of remote control by a joystick or buttons. The robot is controlled by iPhone like a handle bar, since acceleration sensors of iPhone are used in the proposed method. The sensors measure the angles changed on the xyz coordinates of iPhone. And their sensor values are stabilized by digital filters. Bluetooth is chosen for communication between a mobile robot and iPhone. In this paper, four type methods are considered and one of the methods is selected for remote control of a mobile robot. Experimental results show that the robot is easily and conveniently controled by the tangible interface based on iPhone.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.1
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• pp.10-18
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• 2007

In this paper, we address the node positioning method for minimizing the overlap sensing areas in wireless sensor networks with adjustable sensing ranges. To find a optimal node position, we derive a optimal equations by using the overlapped areas, each node's radiuses and expended angles of opposite neighboring nodes. Based on it, we devise a new node positioning method, called as ASRC(Adjustable Sensing Ranges Control). Unlike existing condition based model, our proposed method is derived from mathematical formula, and we confirm its validity through various simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7B
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• pp.1342-1350
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• 1999

In this paper, we have developed and analyzed the 2.45GHz microwave RFID system. Which is composed tag and interrogator using custom IC, and we have made the software driving the hardware for the bidirectional data transmission method. Using 3.6V power supply was used, the optimal identification range in the information transmission of the designed microwave RFID system operating at 9,600bps was l0m. In the control circuit of the tag, the low current consumption of 15$mutextrm{A}$ and the tag data transmission rate of 90% when the moving velocity was 80km/h.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.192-193
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• 2011

자기유도방식 무선전력전달용 DQ 인버터의 정적 동작 특성 및 동적 응답 특성을 해석하는데 복소 라플라스 변환을 페이저 변환된 회로에 적용하는 방법을 사용하였다. 최근에 발표된 복소 라플라스-페이저 변환이론이 교류 컨버터의 동적특성을 해석하는데 있어 실용적으로 아주 유용하다는 것이 연구를 통해서 확인되었다. 기존의 라플라스 변환을 복소수 영역으로 확대한 복소 라플라스 변환을 페이저 변환된 회로에 적용하면 전달함수를 구할 수 있어, 시스템의 안정도 분석과 제어기 설계가 가능해진다. 본 논문에서는 이론식을 유도하고 시뮬레이션을 통해 검증하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.113-116
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• 2010

최근 차량 내부의 전자 제어장치에 대한 운전자의 편의성 및 안전성의 요구 수준이 높아지고 있으며 이러한 수요자의 요구를 만족시키기 위하여 자동차 업계에서도 첨단식 편의기능을 갖춘 자동차의 개발에 많은 초점을 모으고 있는 추세이다. 이에 대응해 차량 내부의 전자시스템 사이에 상호 통신을 위한 차량용 네트워크 기술도 빠르게 발전하고 있다. 특히 대용량 데이터를 고속으로 전송할 수 있도록 높은 대역폭을 제공하는 차량용 광 네트워크가 주목 받고 있으며 현재 일부 차량에 도입되어 양산되고 있는 추세이다. 이러한 기술적 변화에 맞춰서 본 연구에서는 차량용 광 통신 네트워크 표준인 "MOST"의 백본망을 구축하여 무선 이동 단말기 보드(MV Board)를 통해 MOST 광 네트워크에 연결되어 있는 여러 장치들에 대한 다양한 정보를 수신할 수 있고 MOST네트워크 동작 및 운영상태를 확인해 볼 수 있는 시스템을 구성하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.2
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• pp.57-65
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• 2008

Wireless sensor networks achieve environment monitoring and controlling through use of small devices of low cost and low power. Such network is comprised of several sensor nodes, each having a microprocessor, sensor, actuator and wired/wireless transceiver inside a small device. In this paper, we employ the sensor networks in order to design and implement a real-time vehicle safety system. Such system can inform the safe velocity in a specific weather condition to drivers in advance through analyzing the weather data collected from sensor networks. As a result, the drivers can prevent effectively accidents by controlling their car speed.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.3
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• pp.60-67
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• 2011

Visible light communication system transmits data by controlling light emission of LED and receives data through photo detecter, which is considered as one of strong candidates of next generation wireless communication systems. The transmission capacity of visible light communication system depends on light intensity emitted from LED, sensitivity of PD, distance between transmitter and receiver, angle of incidence at the receiver. In particular, the receiver's vertical and horizontal movement changes distance between transmitter and receiver and angle of incidence, which may degrades transmission capacity of system. In this paper, we propose an estimation algorithm of receiver's position and angle based on tracking of received light intensity for indoor visible light communication systems. The performance evaluation of proposed algorithm confirms that the estimation algorithm of receiver's position and angle is quite important for visible light communication system to improve its transmission capacity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.12
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• pp.991-997
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• 2013

A new frequency tuning scheme and a transconductor with a wide tuning range and low harmonic distortion is presented. This frequency tuning technique is based on the relationship between the time-constant and the elapsed times in charging a capacitor up to a certain level. Its structure is as simple as that of a conventional tuning scheme using a VCF(Voltage-Controlled Filter) and it does not need a pure sine wave but uses a CLK(Clock) pulse as a reference signal, which is easily obtained from on-chip system clocks or external X-tal oscillators. When a certain reference CLK is given, without complex capacitor arrays the pole frequency of the filter can be controlled continuously in the frequency domain. Simulation results are presented to confirm the operation of the proposed approach.

• Journal of Internet Computing and Services
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• v.7 no.2
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• pp.81-92
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• 2006

Recently, the number of mobile phone and PDA users has been rapidly increased. Such monitoring and control applications as geographical and traffic information systems are being used widely with wireless devices. In this paper, we introduce the mobile M/VC application framework that supports the rapid constructions of mobile monitoring and control (M/VC) applications. The mobile M/VC application framework uses the mobile Observer/Observable pattern that extends the Java's Observer/Observable for automatic interactions of server and client objects in wireless environments. It also provides the Multiplexer and Demultiplexer classes that supports the assembly feature of Observer and Observable objects. To construct an application using the framework, developers just need to create necessary objects from the Observable and MobileObserver classes and inter-connect them structurally(like the plug-and-play style) through the Multiplexer and Demultiplexer objects. Then, the state change of Observable objects is notified to the connected Observer objects and user's input with Observer objects is propagated to Observable objects. These mechanism is the main process for monitoring and control applications. Therefore, the mobile M/VC application framework can improve the productivity of mobile applications and enhance the reusability of such components as Observer and Observable objects in wireless environments.

• Annual Conference of KIPS
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• 2004.05a
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• pp.1497-1500
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• 2004

현재 사용되고 있는 CDMA 망에서 새로이 도입하고자 하는 동기식 IMT-2000과 비동기식 IMT-2000인 WCDMA을 제공하고자 하는 사업체들은 기지국 증설의 장소와 비용부담, 시스템 업그레이드 등의 유지보수 문제로 인해 많은 어려움을 겪고 있다. 이를 해결 하기 위해 많은 회사 혹은 연구소에서 해결 방안을 연구 중이며 모든 이동통신을 하나의 시스템으로 서비스 할 수 있는 방법으로 SDR 기법이 많이 논의 되고 있다. 본 논문에서는 주로 DSP 기술을 응용하여 SDR 기법을 시스템에 적용하여 하나의 시스템에서 소프트웨어 업데이트만으로 시스템의 물리계층을 제어하여 시스템의 유연성을 가지게 하는 구현방안을 CDMA/WCDMA을 중심으로 제시하였다.