• 한국멀티미디어학회논문지
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• 제9권6호
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• pp.735-741
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• 2006

In the near future, the wireless home networks will connect several devices at home. Due to the broadcast nature of a wireless network, anyone can hear and capture communication. Thus, we need to protect our network from attacks outside the house. In this paper, we propose and implement a security system that provides different levels of the security services to heterogenous home devices. To reduce the communication cost and workload of the server, home devices send the encrypted messages directly instead of sending through the sever. We implement our security system on laptops using JAVA and our security system achieves the better performance with the large number of devices and messages in a network. In order to prove that our security system is secure against various attacks, we analyze the security of our security system using attack trees.

• International journal of advanced smart convergence
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• 제4권2호
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• pp.1-5
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• 2015

The necessity to distribute energy wirelessly has been spurred by the tremendous growth in the use of portable devices. Mobile devices have become ubiquitous and the circuits within them have been optimized to consume extremely low amounts of power. Such portable electronic sets are in constant use and the frequent need to recharge them; using conventional wired mechanisms have hindered the mobility of users. Wireless transmission of energy to power-up devices has been proposed since the days of Tesla and since then many theories and methods have been invented. This paper discusses some of those techniques briefly.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.177-178
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• 2005

Wireless 1394 over IEEE802.15.3 must allow a data reserved for delivery over a wired 1394 network to be delivered over an IEEE802.15.3 wireless network through bridging IEEE 1394 to IEEE802.15.3. Isochronous transfers on the 1394 bus guarantee timely delivery of data. Specifically, isochronous transfers are scheduled by the bus so that they occur once every $125\;{\mu}s$ and require clock time synchronization to complete the real-time data transfer. IEEE1394.1 and Protocol Adaptation Layer for IEEE1394 over IEEE802.15.3 specify clock time synchronization for a wired 1394 bus network to a wired 1394 bus network and wireless 1394 nodes, which are IEEE802.15.3 nodes handling 1394 applications, over IEEE802.15.3. Thus, the clock time synchronizations are just defined within a homogeneous network environment like IEEE1394 or IEEE802.15.3 until now. This paper proposes new clock time synchronization method for wireless 1394 heterogeneous networks between 1394 and 802.15.3. If new method is adopted for various wireless 1394 products, consumer electronics devices such as DTV and Set-top Box or PC devices on a 1394 bus network can transmit real time data to the AV devices on the other 1394 bus in a different place via IEEE 802.15.3.

• 정보보호학회논문지
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• 제23권2호
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• pp.169-179
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• 2013

최근 스마트 폰, 스마트 패드와 같은 모바일 디바이스의 발전과 무선 네트워크 및 이동통신 네트워크의 발전으로 모바일 디바이스를 이용하는 서비스는 증가하고 있다. 그러나 무선 네트워크는 유선 네트워크에 비해 보안에 취약하므로 보다 강한 보안의 적용이 필요한 반면 배터리 기반의 모바일 디바이스는 낮은 계산 능력과 메모리 공간의 제약 및 무선통신에 사용되는 비용이 높기 때문에 보안의 적용은 효율적이어야 한다. 따라서 본 논문에서는 모바일 디바이스를 이용한 서비스에서 요구되는 보안 요구사항을 충족시키고 모바일 환경에 적합한 티켓 기반의 인증 기법을 제안한다.

• ETRI Journal
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• 제43권5호
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• pp.909-915
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• 2021

GaAs on Si grown via metalorganic chemical vapor deposition is demonstrated using various Si substrate thicknesses and three types of dislocation filter layers (DFLs). The bowing was used to measure wafer-scale characteristics. The surface morphology and electron channeling contrast imaging (ECCI) were used to analyze the material quality of GaAs films. Only 3-㎛ bowing was observed using the 725-㎛-thick Si substrate. The bowing shows similar levels among the samples with DFLs, indicating that the Si substrate thickness mostly determines the bowing. According to the surface morphology and ECCI results, the compressive strained indium gallium arsenide/GaAs DFLs show an atomically flat surface with a root mean square value of 1.288 nm and minimum threading dislocation density (TDD) value of 2.4×10⁷ cm^-2. For lattice-matched DFLs, the indium gallium phosphide/GaAs DFLs are more effective in reducing the TDD than aluminum gallium arsenide/GaAs DFLs. Finally, we found that the strained DFLs can block propagate TDD effectively. The strained DFLs on the 725-㎛-thick Si substrate can be used for the large-scale integration of GaAs on Si with less bowing and low TDD.

• 패션비즈니스
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• 제26권5호
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• pp.135-152
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• 2022

This study aimed to evaluate the user experience of hearable devices for seniors and suggest possible development directions. A literature review, case study, and in-depth interviews were conducted. Based on the literature review, convenience, accessibility, transmissibility, wearability, aesthetics, and interest were determined as the user experience factors of hearable devices. Then, in-depth interviews were conducted with 12 participants aged 60 or older regarding four devices. Participants tried four different types of wireless earphones which were selected based on a case study: open-type, kernel-type, neckband-type, and earring-type. Regarding convenience, the participants preferred to carry small devices and regarding accessibility, participants responded positively for most product types. For transmissibility and wearability, there were differences depending on whether devices were put on correctly, but the participants preferred products that did not wholly block external sounds. For aesthetics, participants preferred small and cutting-edge designs. Interest was noticeable among those who had not used the devices before, and for stability, the neckband-type was the most preferred. Based on the results we suggest designing small cutting-edge designs and button-type assist devices, not blocking the external sound, providing a participation program, simplifying device functions, and establishing a method that can be combined with and stored in clothes and a delivery method that can signal danger.

• 디지털산업정보학회논문지
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• 제9권1호
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• pp.9-23
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• 2013

In recent days, there are many researches of wireless LAN services as the communication environment of wireless LAN are so improved that a lot of services are available in wireless environments. The frequency of the wireless LAN is a general resource that can be used to everyone without any permission. Many technologies using this ISM (Industry Science Medical) frequency band are developed fast and widely. But, as many devices use the same frequency band at th same time, the service quality is degraded and the speed of the service rate id degraded by the result of the interference. For overcome this problem, we must provide the new technology of the mobile devices and a new cell design scheme for obtaining maximum throughput that considering the wireless environments effectively. In this paper, we explain the main technology at the IEEE 802.11n environments and proposes the optimal cell design and reference model for gaining maximum performance to many mobile devices at the same time by investigating real environment testing results.

• Journal of Magnetics
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• 제22권2호
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• pp.344-351
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• 2017

Wireless magnet pumps are used in medical applications and are particularly useful as artificial heart ventricular assist devices (VADs). To investigate wireless operation of magnetic pumps, we fabricated three types of magnetic impellers using bonded magnets by blending magnetic powders of SmFeN, NdFeB, and Sr-ferrite. We investigated the magnetic properties of the fabricated magnetic impellers, which are driven by the application of magnetic coupling with an external driving magnet or external coil system, without a driving motor, shaft, or mechanical bearings. The use of wireless magnetic pumps is therefore not complicated by critical issues of size, heat, and vibration, which are very important issues for blood pumps. The magnetic properties of the impellers, such as their rotational speed, driving torque and hydrodynamic performance, determine their wireless driving ranges. We conducted performance evaluations of the impeller's magnetic wireless manipulation, heat, and vibration. In addition, we carried out an animal test to confirm the suitability of the wireless magnetic pumps for use as biventricular assist devices (BiVADs).

• 디지털융복합연구
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• 제12권4호
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• pp.285-291
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• 2014

최근 무선 통신장치들이 매우 빠르게 발전되고 사용자에게 보급되고 있다. 이로 인해서 기존의 유선 네트워크 장치들과 새로운 무선 네트워크 장치들을 통합한 새로운 메쉬 네트워크에 대한 요구가 급속히 발전하고 있다. 이런 유 무선 통합 네트워크 환경에서 자동으로 네트워크를 구성하고, 이런 환경에서 사용자 또는 유 무선 통신장치에 대해 인증서비스를 반드시 제공해야만 한다. 하지만 현실적으로 이런 서비스를 제공하고 있지 못하다. 그러므로 본 논문에서 유 무선 통합 네트워크 환경에서 오픈플로우를 사용해 네트워크를 자동으로 구성하고, 커베로스를 응용한 사용자 인증시스템을 제안하였다. 우리가 제안한 인증시스템은 장치 또는 사용자에 대한 인증서비스를 제공할 수 있을 뿐만 아니라, 비밀성, 무결성 서비스를 제공할 수 있다. 추가로 중간자공격에 대해서도 막을 수 있다.

• 한국산학기술학회논문지
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• 제22권1호
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• pp.294-298
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• 2021

최근 많은 전자 기기들이 무선센서 네트워크 기술들을 접목하면서, 다양한 종류의 센서들이 무선센서 네트워크로 연결하여 사용할 수 있게 되었다. 하지만, 이런 무선센서 네트워크 장비들은 다양한 종류의 네트워크 기술들을 사용하는 데, 각각의 네크워크 기술에 따라 장단점이 존재한다. 따라서 이런 장단점을 잘 고려하여 적용하려는 분야와 목적에 부합할 수 있도록 최적으로 잘 선택하여야 한다. 특히 자기장 관련 센서는 다른 센서들과 달리 복잡한 센서 데이터를 처리함에 있어서, 자기장 센서만의 독특한 특징과 성질이 존재하기 때문에, 개발 초기에 잘 이해한 후에 설계를 하여야 한다. 본 논문에서는 자기장 필드에 발생하는 자기장 센서 데이터의 비선형 데이터를 처리할 수 있는 저가이면서 소형의 웨어 러블 장비를 제안하였다. 또한 무선 센서 네트워크 기술들을 선택하는 방법에 대해서 논의를 하고, 실제 자기장 센서 장치들이 네트워크로 구성하는 방법을 소개하였다. 결론적으로 개발된 웨어러블 자기장 센서장치가 구성하는 무선 센서 토포러지를 제시하고, 이 무선센서 네트워크 망에서 실제 데이터 전송의 성능 및 효능을 보였다.