• Proceedings of the Korean Information Science Society Conference
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• 2006.10a
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• pp.326-330
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• 2006

배터리를 사용하는 소형 임베디드 시스템은 효과적인 전력관리가 필요하다. 그러나 현재까지 개발된 전력관리 기법들은 대부분 운영체제와 하드웨어를 대상으로 하고 있어 개발 플랫폼에 종속적인 특징을 갖는다. 따라서 시스템을 개발할 때마다 지원하는 전력관리 기법을 하드웨어나 운영체제에 따라 여러 번 개발을 해야 하는 단점이 있다. 본 논문에서는 하위 계층에서 지원하는 전력관리 기법에 관계없이 동일한 기능을 제공하는 웨어러블 컴퓨터용 전력관리 미들웨어를 설계하였다.

• ETRI Journal
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• v.43 no.4
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• pp.617-629
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• 2021

Although the actual visual simultaneous localization and mapping (SLAM) algorithms provide highly accurate tracking and mapping, most algorithms are too heavy to run live on embedded devices. In addition, the maps they produce are often unsuitable for path planning. To mitigate these issues, we propose a completely closed-loop online dense RGB-D SLAM algorithm targeting autonomous indoor mobile robot navigation tasks. The proposed algorithm runs live on an NVIDIA Jetson board embedded on a two-wheel differential-drive robot. It exhibits lightweight three-dimensional mapping, room-scale consistency, accurate pose tracking, and robustness to moving objects. Further, we introduce a navigation strategy based on the proposed algorithm. Experimental results demonstrate the robustness of the proposed SLAM algorithm, its computational efficiency, and its benefits for on-the-fly navigation while mapping.

• Journal of Digital Contents Society
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• v.19 no.6
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• pp.1027-1032
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• 2018

Recently, new content for e-leisure, including e-sports and e-games, has become necessary. To meet this requirement, e-leisure mobile AR studies which track human are underway. The tracking performance at long distances is important because e-leisure mobile AR is used in outdoor environments. However, conventional mobile AR applications such as SNOW and Snapchat have the disadvantage of low tracking performance at long distances. Therefore, we propose an e-leisure mobile AR in outdoor environments. The proposed e-leisure mobile AR can estimate the position of the head in outdoor environments at long distances by using color markers and the human body ratio, and then augment a virtual object at the estimated position. The performance of the proposed e-leisure mobile AR was evaluated by measuring the tracking performance and processing time.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.4
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• pp.267-273
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• 2007

A fractional-N frequency synthesizer supports quadruple bands and multiple standards for mobile broadcasting systems. A novel linearized coarse tuned VCO adopting a pseudo-exponential capacitor bank structure is proposed to cover the wide bandwidth of 65%. The proposed technique successfully reduces the variations of KVCO and per-code frequency step by 3.2 and 2.7 times, respectively. For the divider and prescaler circuits, TSPC (true single-phase clock) logic is extensively utilized for high speed operation, low power consumption, and small silicon area. Implemented in $0.18-{\mu}m$ CMOS, the PLL covers $154{\sim}303$ MHz (VHF-III), $462{\sim}911$ MHz (UHF), and $1441{\sim}1887$ MHz (L1, L2) with two VCO's while dissipating 23 mA from 1.8 V supply. The integrated phase noise is 0.598 and 0.812 degree for the integer-N and fractional-N modes, respectively, at 750 MHz output frequency. The in-band noise at 10 kHz offset is -96 dBc/Hz for the integer-N mode and degraded only by 3 dB for the fractional-N mode.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.294-297
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• 2006

Using a single LC panel and two lighting systems, we have developed an advanced LCD system called "Double-Sided LCD." It has only one LC panel and two lighting systems, but it can display images of the same size and resolution on both the front and the rear side. Furthermore, utilizing a simple and thin lighting system we have reduced dramatically its module thickness up to 3.0mm, much thinner than that of conventional dual-type LCD, which is quite appropriate for the use of mobile applications.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.568-570
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• 2005

정보통신기술이 급속히 발전하는 가운데 최근 RFID기술이 주목받고 있다. 이미 물류관리 분야에서는 실용화 되었고 다른 분야로의 응용연구도 계속되고 있다. 최근에는 RFID기술을 휴대폰에 융합한 모바일 RFID(Mobile RFID)라는 개념이 제안되었으며 그 실용화를 위한 연구가 활발히 진행되고 있다. 모바일 RFID기술은 통신기기와 센서기기의 통합형이라는 점에서 홈네트워크 시스템에 적용하기 좋은 기술이다. 따라서 본 논문에서는 모바일 RFID기술을 홈네트워크에 적용하여 홈네트워크 제어기로 활용하는 방안을 제안하였다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.170-170
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• 2004

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.12
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• pp.3133-3151
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• 2012

The optimal price strategy selection of two bounded rational cognitive mobile virtual network operators (MVNOs) in a duopoly spectrum sharing market is investigated. The bounded rational operators dynamically compete to sell the leased spectrum to secondary users in order to maximize their profits. Meanwhile, the secondary users' heterogeneous preferences to rate and price are taken into consideration. The evolutionary game theory (EGT) is employed to model the dynamic price strategy selection of the MVNOs taking into account the response of the secondary users. The behavior dynamics and the evolutionary stable strategy (ESS) of the operators are derived via replicated dynamics. Furthermore, a reward and punishment mechanism is developed to optimize the performance of the operators. Numerical results show that the proposed evolutionary algorithm is convergent to the ESS, and the incentive mechanism increases the profits of the operators. It may provide some insight about the optimal price strategy selection for MVNOs in the next generation cognitive wireless networks.

• Information Systems Review
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• v.17 no.3
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• pp.135-157
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• 2015

Mobile giving platform is a new type of giving platform which offers donation service through mobile application. Mobile giving platform has developed differently from offline giving platform in the way that induces continuous donation. The purpose of this study is to investigate why mobile giving platform has adopted different strategy, and how it leads to continuous contribution. We conducted a case study with two successful mobile giving platforms; Bigwalk and Tree Planet. The analysis of the strategy is based on the construal level theory which explains the relationship between psychological distance and construal level. The result shows that the users' psychological distance toward giving platform has decreased with the environmental change, offline to mobile. Consequently the mobile giving platform offers services which form low level of construal for encouraging continuous participation. This finding suggests the importance of offering suitable construal level in services, and design guideline for mobile giving platforms.

• 한국정보통신설비학회:학술대회논문집
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• 2003.08a
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• pp.20-22
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• 2003

본 논문에서는 Photonic Bandgap(PBG)를 공진 특성을 이용하여 마이크로파 발진기의 위상잡음을 줄이기 위한 기술을 제시한다. 마이크로스트립 라인으로 구현한 공진기는 낮은 Q(Quality factor)를 가진다. PBG를 적용했을 때 공진기의 Q값을 높여줌으로써 발진기의 위상잡음 특성이 향상됨을 보이고자 한다.