• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.565-568
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• 2016

Recently, the number of illegal parking is increasing as the number of cars are increasing. Especially, people who use residential parking permit program are in trouble because of illegal parking. The most typical example is that people who use residential parking permit are damaged in expense, etc and various social issues such as legal actions are caused by illegal parking. In this paper, we discuss about the arduino design for the system and uploading the location information to use the location information for a parking system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.461-462
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• 2016

IPS 측위는 GPS음영 지역인 실내의 특정 위치 정보를 판단하는 시스템으로 현재 위치에서 발생되는 신호 정보를 수집하는 시스템과 이 신호들로 구성된 실내 측위 지도, 측위 위치를 결정하기 위한 알고리즘 등에 따라 여러 종류로 나누어진다. 대표적인 IPS로 2.4Ghz, 5.0GHz 대역의 무선 신호(WiFi, BLE, Sensor Network, etc)를 활용하는 RF신호 기반 WPS 등이 있다. RF 신호를 기반으로 하는 실내 측위는 발생 기기의 고장, 장애물 발생, 채널 간섭 현상 등으로 인해 측위 시점 수집된 신호와 구축된 지도의 신호 정보가 달라 측위 정확도가 낮아지는 경우가 발생한다. 본 논문에서는 앞서 언급한 문제점을 해결하기 위해 기존 RF 환경을 사용하는 IPS 방안에 대하여 분석한다. 또한 RF 이외의 실내 측위 기술들에 대해서도 설명하고 측위 정확도를 위해 단일 측위 방식이 아닌 복합 측위 방식에 대한 설계를 제안한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.10-14
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• 2019

The number of security incidents is increasing as the Internet of Things(IoT) is distributed widely. The security incidents of IoT can cause financial damages. Moreover, It can become direct threats to humans. In order to prevent these problems, the security installation for IoT devices is important. This paper describes the definition of IoT devices, security incident case, architecture, and the security threats that can occur when a device is connected to network without security installation.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.100-102
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• 2011

스마트폰의 급속한 확산으로 모바일 디바이스를 위한 개방형 플랫폼인 안드로이드의 시장 점유율이 지속적으로 증가하고 있다. 안드로이드는 미디어 프레임워크, 카메라, Wi-Fi, GPS 등에 필요한 하위 하드웨어 드라이버만 개발하면 보다 상위 계층은 기본적으로 제공되는 라이브러리와 프레임워크를 기반으로 짧은 시간 내에 어플리케이션 개발이 가능하다. 본 논문에서는 스마트폰의 주요 서비스인 모바일 방송 어플리케이션 개발을 위한 시스템을 제안한다. 제안한 시스템은 안드로이드 소프트웨어의 계층적 스택 구조로 되어 있으며, 이를 활용한 차세대 모바일 방송 규격인 AT-DMB 수신기를 설계 및 구현하였다. 또한, 연구개발 결과물의 수신 기능을 검증하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5506-5511
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• 2012

u-Wellness is widely applicable to individuals and medical service providers such as hospitals and it includes u-fitness and video health counselling services at the side of the provider and stress management, obesity management, and the amount of exercise at the side of the individual. In this paper, we design and implement a smart health care system which uses the authentication device to identify an individual and the user's smart phone. Our system records and manages the amount of exercise on the basis of the prescription of health care professionals through the exercise equipment and Wi-Fi communication. Therefore, our system helps user do optimized amount of exercise through the health care professional's prescription. And our system quantifies the results of the measurement of body fat measuring machines and experts to build the database and automatically schedule.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.8
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• pp.820-830
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• 2013

As wireless traffic drastically increase with the expansion of smart equipment, it is necessary to develop spectrum sharing technologies and introduce spectrum sharing policy for utilizing limited radio resources efficiently. In order to meet these new changes, this parper investigated the government-held (or license) spectrum to seek candidate frequency bands of spectrum sharing. Based on the database of the existing radio station, the investigated candidate frequency bands of spectrum sharing was experimented locally, considering the central frequency, bandwidths, and the region where the radio station is usedIn conclusion, we found out about 901 MHz bandwidths for regional spectrum sharing within the spectrum of 1~4.5 GHz. These bandwidths can be utilized in M2M and WiFi services, etc. based on spectrum sharing technology in the future.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.8
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• pp.571-575
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• 2018

The moisture content of a coffee bean affects its permittivity, and changing the moisture content of a coffee bean changes the taste of the coffee. The variation in the moisture content of a coffee bean can be predicted by the change in frequency and reflection coefficient values with respect to the variation in the permittivity of the bean when it is placed on a patch antenna. In this study, a dual-band patch antenna is designed, which has a moisture measurement band of 3.8~4 GHz that can measure the moisture level of a material; the antenna has a Wi-Fi transmit and receive band of 2.45 GHz. Through simulations and measurements, this study proved that the level of return losses changed from 3.6 to 4 GHz when the moisture content of a coffee bean changed from 2 to 15%. The moisture levels of rice and other beans can be measured with the designed antenna, which can be applied to various applications.

• ETRI Journal
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• v.36 no.2
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• pp.317-320
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• 2014

A balanced RF duplexer with low interference in an extremely narrow bandgap is proposed. The Long-Term Evolution band-7 duplexer should be designed to prevent the co-existence problem with the WiFi band, whose fractional bandgap corresponds to only 0.7%. By implementing a hybrid bulk acoustic wave (BAW) structure, the temperature coefficient of frequency (TCF) value of the duplexer is successfully reduced and the suppressed interference for the narrow bandgap is performed. To achieve an RF duplexer with balanced Rx output topology, we also propose a novel balanced BAW Rx topology and RF circuit block. The novel balanced Rx filter is designed with both lattice- and ladder-type configurations to ensure excellent attenuation. The RF circuit block, which is located between the antenna and the Rx filter, is developed to simultaneously function as a balance-tounbalance transformer and a phase shift network. The size of the fabricated duplexer is as small as $2.0mm{\times}1.6mm$. The maximum insertion loss of the duplexer is as low as 2.4 dB in the Tx band, and the minimum attenuation in the WiFi band is as high as 36.8 dB. The TCF value is considerably lowered to $-16.9ppm/^{\circ}C$.

• Journal of Internet Computing and Services
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• v.12 no.4
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• pp.173-180
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• 2011

Various smart-phone applications for location-based service are enabled through mobile communications such as 3G and WiFi. We have developed MARS, an advanced location-based route-search application based on the Android platform. It provides three functions: route-registration, route-search, and route-evaluation. These functions are dynamically maintained by a web server, a database server, and user mobile terminals. As users can update location information using their smart-phone devices, servers provide the information and allow users to add, modify, and remove their own information as well as adding comments to others, while existing map services do not support direct inputs from users. We show our implementation process and demonstration of its operations. We also show the comparison results with existing services. Through these results, we can confirm that MARS can achieve better performance.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.3
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• pp.303-309
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• 2011

Situation awareness services which increasingly expand their influence in everyday life can be classified into location-based service and social network service. Their quality of service (QoS) can be differed based on the location accuracy of smart phones and accuracy of directional recognition technology. This study was conducted to analyze GPS, digital compass, radio communication, and geospatial web information which can provide a clue in using the situation aware services based on lab experiments and surveys. According to the result of lab experiment on accuracy of determining location / direction with smart phones, owing to inherent lack of indoor accuracy in determining position and direction, as well as errors in spatial data used as platform, it was found that devices were not provided with sufficiently accurate data when using the situation aware services indoors compared to outdoors. To enhance accuracy of determining indoor positions, there are several methods including location metering based on Wi-Fi, which had several problems compared with GPS used in outdoor environment. Thus, it was determined that more study would be necessary to solve these issues.