• 제어로봇시스템학회논문지
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• 제11권12호
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• pp.1045-1050
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• 2005

This paper describes a design experience of a low-cost 6 DOF spatial tracker system where relative low accuracy and relatively long ranges, wireless communication will be achieved by means of low cost accelerometers and gyros with contemporary microprocessor. However, there are two key problems; one is the bias drift problem and the other is that single or double integration of acceleration signal suffers not only from noise but also from nonlinear effects caused by gravity. To be specific, beginning and stopping of hand motions needs to be accurately detected to initiate and terminate integration process to get position and pose of the hand from accelerometer and gyro signals, since errors due to noise and/or hand-shaking motions accumulated by integration processes. Several experimental results are shown to validate our proposed algorithms.

• 한국항해항만학회지
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• 제35권7호
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• pp.563-568
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• 2011

The various properties such as the electric current distribution, resonant frequency and radiation patterns of open-ended meander slot antenna placed on a small ground plane, are investigated to give the help in performing antenna design. Based upon these characteristics, the designed antenna which is only 22mm($0.06{\lambda}_g$) in height and 31mm($0.09{\lambda}_g$) in width can operate at the 433 MHz with the measured radiation efficiency of 8% and end-fire radiation pattern. These properties make the antenna suitable for the handheld device such as the wireless remote controller.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2003년도 가을 학술발표논문집 Vol.30 No.2 (3)
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• pp.460-462
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• 2003

PDA(Personal Data Assistant)나 Handheld PC와 같은 모바일 디바이스(Mobile Device)를 이용하여 주소록이나 일정관리와 같은 개인 정보를 관리하는 것이 일반적인 추세이다. 모바일 디바이스는 그 특성상 중요한 정보를 신뢰성 있는 서버와 같은 컴퓨터에 중복 저장하는 것이 필요한데, 동일한 데이터를 중복 저장하면 데이터 동기화(Data Synchronization)를 통하여 일치성을 유지하도록 해야 한다. 그러나 동기화 과정에서 데이터 충돌이 발생할 수 있다. 본 논문에서는 이러한 데이터 충돌에 대한 해결 정책을 제시하였고, 그 중 서버 우선 정책과 클라이언트 우선 정책에 필요한 해결 규칙을 설명하였다. 서버 우선 정책은 서버에 이미 존재하고 있는 값을 유지하는 것을 기본으로 하는 정책이며, 클라이언트 우선 정책은 클라이언트가 요청한 값이 우선하는 정책이다.

• 한국정보처리학회논문지
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• 제7권2S호
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• pp.666-677
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• 2000

In this paper, we present a design and implementation of HDML(Handheld Device Markup Language) authoring tool that can create and mange HDML documents easily and conveniently, HDML is a markup language which enable acces to the Web using small mobile equipment through mobile networks. The basic limitation of mobile equipments and technical difficulties such as representation of HDML deck/card, definition of activation in each card and management of Hyper-link between cards are solved, in the development process of the HDML authoring tool.

• 한국광학회:학술대회논문집
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• 한국광학회 2005년도 하계학술발표회
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• pp.204-205
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• 2005

Studies on display has been requested some major changes due to the high growth of the handheld terminal market. Therefore, the self emitting OLED(Organic Light Emitting Diode) has been interested as a next generation flat plane display because of its preeminent characteristics such as quick response characteristics, higher performance viewing angle, low power consumption, and panel floating. However, a trend of the display market is moving to three dimensional image processing instead of two dimensional flat display and various researches on display using hologram makes up for the difficulty in three dimensional display using typical flat display. In this study the Lenticular Screen Printing method is presented so that it can be applicable to organic semiconductor display devices and makes possible three dimensional display using flat display for complement the drawback of inorganic semiconductor.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2005년도 춘계학술대회
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• pp.131-138
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• 2005

Recommender systems have been widely advocated as a way of coping with the problem of information overload in e-business environment. Most of the existing recommender systems focused on what kind of items to recommend, although when to recommend to the target customer considering their context is an important issue. Even right item might be a spam advertisement or wrong recommendation for the customer if it can not be recommended at the right context. It is particularly important for recommendations where the user's context is changing rapidly, such as in both handheld and ubiquitous computing environment. Therefore, we propose CARS (Context-Aware Recommender System) based on CBR and context-awareness for ubiquitous computing environment. CBR is used to generate a target customer class and proper context. Context-awareness is used to gather suer context information from sensors, networks, device status, user profiles, and other sources. An illustrative case example is suggested to explain the procedure of CARS.

• 전기학회논문지
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• 제61권1호
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• pp.110-116
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• 2012

This paper proposes a new diversity antenna which is the base of MIMO, tunable and reconfigurable antennas. The antenna has a small size and high inter-antenna isolation resulting from the compact radiating element comprising a meandered line and an open-loop combined in one limited uniplanar space and a modified T-shaped decoupling structure, respectively. In a WiMAX band, the radiating element and the entire antenna are $0.092{\lambda}$ and $0.2216{\lambda}$ in size, which shows effective size-reduction and the gain and efficiency of the proposed antenna attached to the ground of a handheld device are 3.7dBi and 56% acceptable to the industrial standard.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.90.1-90.1
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• 2013

Nature utilizes various of the colorization process. Some species of birds can express their mood of tempers by changing their collagen structures on skin. For example, turkey can change their skin color by expansion of the collagen structures, which are associated with the distinct color changes. Here, we developed bioinspired virus-based colorimetric sensors which can be genetically tuned for target molecule. Using M 13 bacteriophage, we fabricated responsive self-assembled color matrices composed of quasi-ordered fiber bundle structures. These virus matrices can exhibit color change by stimuli through fiber bundle structure modulation. Upon exposure of volatile organic compounds, the resulting multi-colored matrices exhibited distinct color changes with different ratios that can be recognized by the naked eyes. Using the directed evolutionary approaches, we genetically engineered the virus matrix to incorporate binding motif for explosive detection (i.e., trinitrotoluene (TNT)). Through utilizing a common handheld device (i.e., iPhone), we could distinguish TNT molecules down to 20 ppb in a selective manner. Our novel biomimetic virus colorimetric sensor can overcome current limitation for low response selectivity.

• Current Optics and Photonics
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• 제7권2호
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• pp.176-182
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• 2023

Optical coherence tomography (OCT) is being developed to guide various ophthalmic surgical procedures. However, the high cost of the intraoperative OCT system limits its availability mostly to the largest hospitals and healthcare systems. In this paper, we present a design and evaluation of a low-cost intraoperative common-path free-hand scanning OCT system. The lensed fiber imaging probe is designed and fabricated for intraocular use and the free-hand scanning algorithm that could operate at a low scanning speed was developed. Since the system operates at low frequencies, the cost of the overall system is significantly lower than other commercial intraoperative OCT systems. The assembled system is characterized and shows that it meets the design specifications. The handheld OCT imaging probe is tested on multilayer tape phantom and ex-vivo porcine eyes. The results show that the system could be used as an intraoperative intraocular OCT imaging device.

• 한국융합학회논문지
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• 제9권4호
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• pp.9-14
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• 2018

최근 인터넷 속도가 빨라지면서 클라우드 환경에서는 서비스 수신 장치가 일반 PC에서 휴대폰 또는 태블릿 PC 등의 소형 장치로 변화되고 있는 추세이다. 휴대폰 또는 태브릿 PC 등과 같은 소형 장치들은 유선보다는 무선에서 사용되는 경우가 많기 때문에 제3자로부터 악의적으로 개인 정보가 노출될 수 있는 문제점이 많다. 본 논문에서는 다양한 무선 매체를 통해서 서비스되고 있는 클라우드 서비스 중에서 사용자의 프라이버시를 제3자로부터 안전하게 보호할 수 있는 이중 복제키 생성 과정을 통한 사용자 프라이버시 보호 기법을 제안한다. 제안 기법은 복제된 키를 서버와 중간 장치의 동기화를 위해서 사용되며, 사용자의 프라이버시를 보호하는 인증 처리 과정의 시간을 단축하는 것을 목표로 한다. 이 때, 제안기법은 서버와 중간 장치의 동기화에 Interleave()수와 랜덤수를 사용하기 때문에 제3자의 악의적인 공격을 안전하게 예방할 수 있다.